JP2017193991A - Engine state parameter calculating device, engine control system, and engine state parameter calculating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve calculation accuracy of an engine state parameter based on a sensor output of a crank angle sensor. An engine state parameter calculation device includes an acquisition unit that acquires sampling values of a sensor output of a crank angle sensor provided for a crankshaft of an engine at a plurality of time points, and a section within a section where the sensor output rises or falls. Based on the sampling values at the two time points, a reference time point calculation unit that calculates a reference time point when the sensor output becomes a predetermined reference value, and a state of the engine based on the reference time point calculated by the reference time point calculation unit. And a parameter calculation unit that calculates a parameter to be expressed. [Selection diagram] Fig. 7

Description

  The present disclosure relates to an engine condition parameter calculation device, an engine control system, and an engine condition parameter calculation method.

  A technique for calculating an engine speed (an engine state parameter equivalent to a crank angular speed) by measuring a time interval between rising edges of a crank angle signal of a crank angle sensor is known.

JP 2002-89346 A JP 2010-59883 A

  However, it is difficult to accurately generate the rising edge of the crank angle signal due to the limit of the sampling rate when sampling the sensor output of the crank angle sensor. Therefore, it is difficult for the prior art to increase the calculation accuracy of a parameter representing the state of the engine, such as the crank angular speed.

  Accordingly, in one aspect, an object of the present invention is to improve calculation accuracy of an engine state parameter based on a sensor output of a crank angle sensor.

According to one aspect, an acquisition unit that acquires sampling values at a plurality of time points of a sensor output of a crank angle sensor provided for a crankshaft of an engine;
A reference time point calculation unit that calculates a reference time point that is a time point at which the sensor output becomes a predetermined reference value based on the sampling values at two time points within a section in which the sensor output increases or decreases;
There is provided an engine condition parameter calculation device including a parameter calculation unit that calculates a parameter representing the state of the engine based on the reference time point calculated by the reference time point calculation unit.

  It becomes possible to improve the calculation accuracy of the engine condition parameter based on the sensor output of the crank angle sensor.

It is a block diagram which shows an example of the engine torque calculation system by Example 1. FIG. It is a perspective view which shows an example of a crank angle sensor. It is a top view which shows an example of a crank rotor. It is explanatory drawing of the relationship between the shape characteristic of the outer periphery of a crank rotor, and the sensor output of a crank angle sensor. It is a figure which shows the relationship between the sensor output of a crank angle sensor, and the predetermined reference value Vref. It is a figure which shows an example of the hardware constitutions of an engine torque calculation apparatus. 1 is a functional block diagram of an engine torque calculation device according to Embodiment 1. FIG. It is explanatory drawing of the calculation method of the crossing time by a crossing time calculation part. It is explanatory drawing of the relationship between a crossing time and a crank angle. It is explanatory drawing of the calculation method of crank angular acceleration. It is a figure which shows the example of the crossing time calculated with 2 calculation periods, respectively. It is explanatory drawing of the calculation accuracy of the indicated torque by a comparative example. It is explanatory drawing of the calculation precision of the illustration torque by Example 1. FIG. 3 is a flowchart illustrating an example of an engine torque calculation process according to the first embodiment. It is a figure which shows an example of the engine control system containing an engine torque calculation apparatus. It is a functional block diagram of the engine torque calculation apparatus by Example 2. It is explanatory drawing of the calculation method of the maximum arrival time by the maximum arrival time calculation part. 6 is a flowchart illustrating an example of an engine torque calculation process according to a second embodiment. It is a functional block diagram of the engine torque calculation device by Example 3. It is explanatory drawing of a 1st crank angular velocity and a 2nd crank angular velocity. It is explanatory drawing of a 1st crank angular velocity and a 2nd crank angular velocity. 12 is a flowchart illustrating an example of an engine torque calculation process executed by an engine torque calculation device according to a third embodiment. It is explanatory drawing of an electromagnetic pick-up type crank angle sensor. It is a figure which shows an example of the waveform of the sensor output of an electromagnetic pick-up type crank angle sensor. It is a functional block diagram of the engine torque calculation apparatus by Example 4. It is explanatory drawing of the calculation method of the crossing time by Example 4. FIG.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram illustrating an example of an engine torque calculation system 1 according to the first embodiment.

  The engine torque calculation system 1 is mounted on a vehicle including an engine (not shown). The vehicle may be a vehicle that uses only the engine as a drive source, or may be a hybrid vehicle that uses both the electric motor and the engine as drive sources. The kind of engine is arbitrary, for example, a gasoline engine may be sufficient and a diesel engine may be sufficient.

  The engine torque calculation system 1 includes a crank angle sensor 4 and an engine torque calculation device 10.

The crank angle sensor 4 is attached to the engine. The crank angle sensor 4 generates a sensor output representing a crank angle that is a rotation angle of the crankshaft 6 (see FIG. 2) of the engine. For example, the crank angle sensor 4 generates a sensor output in cooperation with a crank rotor (signal rotor) 5 fixed to the crankshaft. As shown in FIGS. 2 and 3, the crank rotor 5 has protrusions (teeth) 5b on the outer periphery at a pitch corresponding to a predetermined crank angle pitch angle Δθ (for example, 6CA pitch) (hereinafter referred to as “pitch angle Δθ”). It is possible to have the missing tooth portion 5a for detecting the top dead center. “CA” represents a crank angle.
In the first embodiment, as an example, the crank angle sensor 4 is an MRE (magneto resistive effect) sensor including a magnetoresistive element. FIG. 4 is an explanatory diagram of the relationship between the shape feature of the outer periphery of the crank rotor 5 and the sensor output of the crank angle sensor 4. FIG. 4 shows a state where the outer periphery of the crank rotor 5 is linearly developed on the upper side, and a lower side of the crank angle sensor 4 corresponding to the shape characteristic of the outer periphery of the crank rotor 5 shown on the upper side. Sensor output is shown. FIG. 5 is a diagram showing the relationship between the sensor output of the crank angle sensor 4 and a predetermined reference value (determination reference voltage).

  When the crank rotor 5 rotates, the teeth 5b of the crank rotor 5 repeatedly move toward and away from the crank angle sensor 4. The crank angle sensor 4 detects a magnetic field change caused by the teeth 5 b of the crank rotor 5, and outputs a pulse-like signal according to the presence or absence of the teeth 5 b of the crank rotor 5. At this time, the pitch θ2 of the pulse-like signal corresponds to the pitch angle Δθ of the crank rotor 5.

  In the section where the crank angle sensor 4 faces the missing tooth portion 5a of the crank rotor 5, the magnetic field does not change, so the sensor output does not change. That is, the crank angle sensor 4 does not output a new rising pulse for the time during which the crank rotor 5 rotates by the angle θ1 while facing the missing tooth portion 5a of the crank rotor 5. The angle θ1 corresponds to (number of missing teeth + 1) × Δθ. Hereinafter, a section (section having an angle θ1) caused by the missing tooth portion 5a in the sensor output is referred to as a “missing tooth section”.

As shown in FIG. 5, the sensor output periodically crosses the predetermined reference value Vref as the crankshaft rotates in a section where the crank angle sensor 4 is opposed to a portion other than the toothless portion 5 a of the crank rotor 5. Specifically, the sensor output crosses the predetermined reference value up and down a total of two times for each pitch angle Δθ as the crankshaft rotates. As described above, the sensor output includes a section in which the predetermined reference value is crossed twice in total up and down for each pitch angle Δθ as the crankshaft rotates in a section of the crank angle of 0 to 720 CA, and a top dead center detecting missing tooth. Section. Hereinafter, a section in which the predetermined reference value Vref is crossed twice in total up and down for each pitch angle Δθ with the rotation of the crankshaft is also referred to as a “non-missing tooth section”. In the non-missing tooth section, every time the sensor output crosses 0 V from negative to positive (upward) (see the circle in FIG. 5), the crank angle is advanced by the pitch angle Δθ. . In the first embodiment, as an example, it is assumed that the sensor output has a constant amplitude based on the predetermined reference value Vref. That is, as shown in FIG. 5, the sensor output periodically _rises and _falls between a fixed maximum voltage V _MAX and a fixed minimum voltage V _MIN, and a predetermined reference value Vref = (V _MAX + V _MIN ) / 2. is there.

  FIG. 6 is a diagram illustrating an example of a hardware configuration of the engine torque calculation device 10. The hardware of the engine torque calculation device 10 may include, for example, a microcomputer, an FPGA (Field Programmable Gate Array), a PLC (Programmable Logic Controller), and the like.

  In the example illustrated in FIG. 6, the engine torque calculation device 10 includes a control unit 101, a main storage unit 102, an auxiliary storage unit 103, and a hardware I / F unit 106.

  The control unit 101 is an arithmetic device that executes a program stored in the main storage unit 102 or the auxiliary storage unit 103, receives data from the storage device, calculates and processes the data, and outputs the data to the storage device or the like. The control unit 101 may include, for example, a CPU (Central Processing Unit), a timer counter, and the like.

  The main storage unit 102 is a ROM (Read Only Memory), a RAM (Random Access Memory), or the like, and is a storage device that stores or temporarily stores programs and data such as application software executed by the control unit 101.

  The auxiliary storage unit 103 is an EEPROM (Electric-Erasable Programmable Read-Only Memory) or the like, and is a storage device that stores data related to application software.

  The hardware I / F unit 106 is an interface with a vehicle network (for example, CAN (Controller Area Network) or the like) or an engine peripheral device (for example, the crank angle sensor 4 or the like) connected by a wired and / or wireless line. It is.

  FIG. 7 is a functional block diagram of the engine torque calculation device 10 according to the first embodiment. The engine torque calculation device 10 includes an A / D converter (Analog-to-Digital) 110, a sample value acquisition unit 111 (an example of an acquisition unit), and a sample value storage unit 114. The engine torque calculation device 10 also includes a cross time point calculation unit 120 (an example of a reference time point calculation unit), a crank angle calculation unit 121, and a cross time point storage unit 122. The engine torque calculation device 10 also includes a crank angular velocity calculation unit 123, a crank angular velocity storage unit 124, a crank angular acceleration calculation unit 130, and an engine torque calculation unit 160 (an example of a parameter calculation unit). Each unit 111, 120, 121, 123, 130, and 160 can be realized by the control unit 101 executing a program in the main storage unit 102. Further, the sample value storage unit 114, the cross time point storage unit 122, and the crank angular velocity storage unit 124 can be realized by the RAM of the main storage unit 102, for example.

  The A / D converter 110 converts an analog input related to the sensor output of the crank angle sensor 4 into a quantized output.

  The sample value acquisition unit 111 acquires sampling values at a plurality of points in time of the sensor output of the crank angle sensor 4 via the A / D converter 110. For example, the sample value acquisition unit 111 samples the sensor output at a predetermined sampling rate via the A / D converter 110. The predetermined sampling rate is set so that sampling values at least at two or more time points can be acquired in an upstream section described later. The predetermined sampling rate may be constant or may be variable according to, for example, the engine speed. The sample value acquisition unit 111 stores the acquired sampling value in the sample value storage unit 114.

  The sample value storage unit 114 has a storage area for storing the sampling values acquired by the sample value acquisition unit 111. The storage area has a capacity for storing, for example, the latest predetermined number or more of sampling values. The sample value storage unit 114 is, for example, a ring buffer, and holds the latest predetermined number or more of sampling values in a FIFO (first-in, first-out) format. The predetermined number is equal to or greater than the number of sampling values used in the cross point calculation unit 120, and is two, for example.

The cross time calculation unit 120 calculates a time point at which the sensor output becomes the predetermined reference value Vref based on sampling values at two time points in a section where the sensor output increases (hereinafter also referred to as “upward section”). The section refers to a section after the sensor output starts rising from the minimum voltage _VMIN and before reaching the maximum voltage _VMAX .

  In the first embodiment, as an example, the cross time point calculation unit 120 is a time point at which the sensor output crosses the predetermined reference value Vref based on sampling values at two time points sandwiching the predetermined reference value Vref in the upstream section of the sensor output. (Hereinafter also referred to as “cross point”). For example, when the sampling value stored most recently in the sample value storage unit 114 exceeds the predetermined reference value Vref from a state where it is less than the predetermined reference value Vref, the cross time calculation unit 120 stores the value in the sample value storage unit 114. The sampling values at the two most recent time points are taken out. Then, the cross time point calculation unit 120 calculates the cross time point based on the extracted sampling values at the two time points. The cross time point calculation unit 120 stores the calculated cross time point in the cross time point storage unit 122.

  FIG. 8 is an explanatory diagram of a cross time calculation method performed by the cross time calculation unit 120. In FIG. 8, time is plotted on the horizontal axis and voltage is plotted on the vertical axis, and a sensor output waveform 70 is shown. In FIG. 8, sampling points s (n−3) to s (n + 2) obtained at the sampling period i (= n−3 to n + 2) are indicated by ◯. A sampling point (and a cross point described later) corresponds to a point at which a two-dimensional position (a position in a two-axis coordinate system as shown in FIG. 8) is determined by voltage information and time information.

  In the example shown in FIG. 8, the sampling values at two time points across the predetermined reference value Vref are the voltage value v (n−1) at the sampling point s (n−1) and the voltage value at the sampling point s (n). v (n). The two time points are time point t (n-1) and time point t (n), and time point tc is a cross time point. The time point is one point on the time axis, and the time represents a length on the time axis. In the following, as an example, the time point t (n-1), the time point t (n), and the cross time point tc are respectively times from a common start time point (for example, timing corresponding to the origin of the time axis in FIG. 8). expressed.

Specifically, the cross time calculation unit 120 calculates the time change rate β of the sensor output between the two time points based on the difference ΔV between the sampling values at the two time points and the time dt between the two time points. . In FIG. 8, the difference between the sampling values at two time points is ΔV, and ΔV = v (n) −v (n−1). The time dt between the two time points corresponds to the sampling rate. Therefore, the time change rate β of the sensor output between the two time points is β = ΔV / dt = (v (n) −v (n−1)) / dt. Then, the cross time point calculation unit 120 calculates the cross time point tc based on the calculated time change rate β. For example, the cross time point tc can be calculated as follows using the time point t (n−1) as a reference.
tc = (Vref−v (n−1)) / β + t (n−1)
Alternatively, the cross time tc can be calculated as follows with respect to the time t (n).
tc = t (n) − (v (n) −Vref) / β
This calculation method is suitable when the sensor output changes linearly between the maximum voltage V _MAX and the minimum voltage V _MIN as shown in FIG. In other words, this calculation method assumes that the sensor output changes at a constant time change rate between the maximum voltage V _MAX and the minimum voltage V _MIN , and the cross point Pc at which the sensor output becomes the predetermined reference value Vref (see FIG. 8). ). Therefore, the cross point Pc related to the cross time point tc is a straight line (slope is β) connecting the sampling point s (n−1) and the sampling point s (n), and a straight line representing the predetermined reference value Vref (slope is 0). ).

  The crank angle calculation unit 121 calculates a crank angle at the cross time based on the cross time calculated by the cross time calculation unit 120. In the first embodiment, as an example, as shown in FIG. 9, the cross time point is the timing at which the crank angle is advanced by the pitch angle Δθ. Therefore, the crank angle at the current crossing time can be calculated by adding the pitch angle Δθ to the crank angle at the previous crossing time. FIG. 9 shows the crank angles CA (k−1), CA (k), and CA (k + 1) calculated in three consecutive calculation cycles (k−1, k, k + 1). tc (k−1), tc (k), and tc (k + 1) are cross time points tc related to the respective calculation periods (k−1, k, k + 1). Note that the time between two crossing points adjacent on the time axis varies depending on the crank angular velocity. For example, the time Δt (k−1) between the cross time tc (k−1) related to the calculation cycle k−1 and the cross time tc (k) related to the calculation cycle k is equal to the cross time tc related to the calculation cycle k. The time Δt (k) between (k) and the cross time point tc (k + 1) related to the calculation cycle k + 1 may be different. In the missing tooth section, the crank angle calculation unit 121 may calculate the crank angle by advancing the angle θ1 (see FIG. 4) instead of the pitch angle Δθ.

  The cross time storage unit 122 includes a storage area for storing the cross time calculated by the cross time calculation unit 120. The storage area has a capacity for storing, for example, the latest predetermined number or more of cross points. The cross point storage unit 122 is, for example, a ring buffer, and holds the latest predetermined number of cross points or more in the FIFO format. The predetermined number is, for example, 2 although it depends on the calculation method in the crank angular velocity calculation unit 123 and the crank angular acceleration calculation unit 130.

  The crank angular velocity calculation unit 123 calculates the crank angular velocity based on the cross time calculated by the cross time calculation unit 120. Specifically, the crank angular velocity calculation unit 123 calculates the crank angular velocity based on the time between two cross points adjacent on the time axis and the pitch angle Δθ in the non-missing tooth section. That is, the crank angular velocity ω (k) in the calculation cycle k is, for example, as follows.

ここで、ｔｃ（ｋ）は、算出周期ｋに係るクロス時点ｔｃであり（図５及び図９参照）、算出周期ｋの直近に算出されたクロス時点ｔｃである。尚、欠歯区間においては、クランク角速度算出部１２３は、ピッチ角Δθに代えて、角度θ１（図４参照）を用いて、クランク角速度を算出してよい。以下では、特に言及しない限り、非欠歯区間における算出方法について説明していく。

Here, tc (k) is the cross time tc related to the calculation cycle k (see FIGS. 5 and 9), and is the cross time tc calculated immediately before the calculation cycle k. In the missing tooth section, the crank angular velocity calculation unit 123 may calculate the crank angular velocity using the angle θ1 (see FIG. 4) instead of the pitch angle Δθ. Hereinafter, a calculation method in the non-missing tooth section will be described unless otherwise specified.

  For example, every time a new cross time is calculated by the cross time calculation unit 120, the crank angular velocity calculation unit 123 calculates the two most recent cross time points (including the newly calculated cross time point) from the cross time storage unit 122. Take out. Then, the crank angular speed calculation unit 123 calculates a crank angular speed based on the last two cross points taken out and the pitch angle Δθ (known), and stores the calculated crank angular speed in the crank angular speed storage unit 124.

  The crank angular speed storage unit 124 has a storage area for storing the crank angular speed calculated by the crank angular speed calculation unit 123. The storage area has a capacity for storing, for example, the latest crank angular speeds for a predetermined number of calculation cycles or more. The crank angular velocity storage unit 124 is, for example, a ring buffer, and holds the crank angular velocity for the latest predetermined number of calculation cycles or more in a FIFO format. The predetermined number is equal to or greater than the number of calculation cycles necessary for the crank angular acceleration calculation process of the crank angular acceleration calculation unit 130, and depends on the crank angular acceleration calculation method. For example, when the crank angular acceleration calculation unit 130 calculates the crank angular acceleration based on the crank angular velocities at the two most recent time points, the predetermined number is, for example, two.

  The crank angular acceleration calculation unit 130 calculates the crank angular acceleration based on the crank angular velocity calculated by the crank angular velocity calculation unit 123. For example, every time a new crank angular velocity is calculated by the crank angular velocity calculating unit 123, the crank angular acceleration calculating unit 130 calculates the crank angular velocity for the two latest calculation cycles from the crank angular velocity storage unit 124 and the cross time point storage unit 122. Take the last two cross points. Then, the crank angular acceleration calculation unit 130 calculates the crank angular acceleration based on the extracted crank angular speeds for the two most recent calculation cycles and the two most recent cross points (see FIG. 10). The crank angular acceleration α (k) in the calculation cycle k can be calculated as follows, for example.

或いは、算出周期ｋにおけるクランク角加速度α（ｋ）は、例えば以下の通り算出されてもよい。

Alternatively, the crank angular acceleration α (k) in the calculation cycle k may be calculated as follows, for example.

尚、この場合は、算出周期ｋにおけるクランク角加速度α（ｋ）は、次の算出周期ｋ＋１のクランク角速度ω（ｋ＋１）等を利用して算出されることになる。

In this case, the crank angular acceleration α (k) in the calculation cycle k is calculated using the crank angular velocity ω (k + 1) in the next calculation cycle k + 1.

  The engine torque calculation unit 160 calculates engine torque based on the crank angular acceleration calculated by the crank angular acceleration calculation unit 130. In the first embodiment, as an example, the engine torque calculation unit 160 calculates the indicated torque. The indicated torque τ (k) in the calculation cycle k can be calculated as follows, for example.

ここで、Jは慣性モーメントを表す。

Here, J represents the moment of inertia.

  Next, with reference to FIG. 11 to FIG. 13, effects of the above-described first embodiment will be described in comparison with the comparative example.

  FIG. 11 is a diagram illustrating an example of cross points calculated in two calculation cycles. FIG. 11 shows a cross time point tc (k−1) related to the calculation cycle k−1 and a cross time point tc (k) related to the calculation cycle k.

In the calculation cycle k−1, as shown on the left side of FIG. 11, the sampling values at two time points sandwiching the predetermined reference value Vref are the voltage value v (m−1) and sampling at the sampling point s (m−1). The voltage value v (m) at the point s (m). The two time points are time point t (m−1) and time point t (m). Accordingly, the cross time point tc (k−1) related to the calculation cycle k−1 is as follows as described above.
tc (k−1) = (Vref−v (m−1)) / β (k−1) + t (m−1)
Where β (k−1) = (v (m) −v (m−1)) / dt
In the calculation cycle k, as shown on the right side of FIG. 11, the sampling values at two time points across the predetermined reference value Vref are the voltage value v (n−1) and the sampling point s at the sampling point s (n−1). The voltage value v (n) at (n). The two time points are time point t (n-1) and time point t (n). Accordingly, the cross time point tc (k) related to the calculation cycle k is as follows as described above.
tc (k) = (Vref−v (n−1)) / β (k) + t (n−1)
Where β (k) = (v (n) −v (n−1)) / dt
Here, the following comparative example is assumed. In the comparative example, a time point when a sampling value larger than the predetermined reference value Vref is sampled is treated as a “cross time point”. Therefore, in the comparative example, the crank angular velocity ω (k) in the calculation cycle k is as follows.

  By the way, due to the limit of the sampling rate when sampling the sensor output, the timing for advancing the crank angle by the pitch angle Δθ is accurately synchronized with the time when the sensor output just crosses the predetermined reference value Vref. It ’s difficult. In other words, if the actual time point at which the sensor output becomes the predetermined reference value Vref is “true value”, it is difficult to make the deviation of the cross time point from the true value constant during the calculation period. For example, assuming that the true value coincides with the cross time calculated by the cross time calculating unit 120 according to the first embodiment, in the comparative example, as schematically shown in FIG. , And may vary relatively greatly between calculation periods. Specifically, the deviation Δtr (k−1) of the cross time with respect to the true value in the calculation cycle k−1 is significantly different from the deviation Δtr (k) of the cross time with respect to the true value in the calculation cycle k. . The fact that the deviation of the cross point relative to the true value fluctuates relatively greatly between the calculation cycles means that the sensor output judgment reference voltage used for calculating the crank angular velocity substantially fluctuates relatively between the calculation cycles. Is equivalent to If the determination reference voltage of the sensor output used for calculation of the crank angular velocity varies between the calculation cycles, naturally, the accuracy of the crank angular velocity is deteriorated. Therefore, in the comparative example, it is difficult to increase the calculation accuracy of the crank angular velocity.

  On the other hand, according to the first embodiment, it is possible to suppress the deviation of the cross point relative to the true value (the cross point calculated by the cross point calculator 120) from fluctuating relatively greatly between the calculation cycles. Specifically, according to the first embodiment, as described above, the cross time point is calculated on the basis of the sampling values at the two time points in the upstream section for each calculation cycle. Since the cross time is calculated based on the time change rate β of the sensor output between the two time points in the up section as described above, it coincides with the true value with high accuracy for each calculation cycle. As a result, it is possible to suppress the deviation of the crossing point from the true value from fluctuating relatively greatly between calculation cycles. Therefore, according to the first embodiment, it is possible to improve the calculation accuracy of the crank angular velocity as compared with the comparative example.

  FIG. 12 is an explanatory diagram of the calculation accuracy of the indicated torque according to the comparative example. FIG. 12 shows, from above, a time series of crank angles calculated from sensor outputs, a time series of crank angular accelerations calculated from crank angular velocities, and a time series L1 of indicated torques calculated from crank angular accelerations. . The time series L1 of the indicated torque based on the calculation is shown together with the time series L2 of the indicated torque based on the actually measured value. The indicated torque based on the actually measured value is calculated based on the change in the cylinder volume obtained from the change in the cylinder pressure obtained from the in-cylinder pressure sensor and the change in the crank angle. FIG. 13 is an explanatory diagram of the calculation accuracy of the indicated torque according to the first embodiment. FIG. 13 shows each time series similar to FIG. The specification of the crank rotor 5 used in this test is that the number of teeth is 60 (pitch angle Δθ = 6 CA) and the number of missing teeth is 4. The specification of the engine is that the number of cylinders is 4, and all the cylinders burn once when the crankshaft rotates twice (720 CA).

  In the comparative example, as shown in FIG. 12, the calculation error with respect to the indicated torque based on the actually measured value is large (the waveform is disturbed). The root mean squared error (RMSE) of the calculation result of the comparative example was 143.77. On the other hand, according to the first embodiment, as shown in FIG. 13, the calculation error with respect to the indicated torque based on the actually measured value is small (the disturbance of the waveform is small). According to Example 1, RMSE is 117.42, and RMSE can be reduced by about 28% compared with the comparative example.

  Next, an operation example of the engine torque calculation device 10 will be described with reference to FIG.

  FIG. 14 is a flowchart illustrating an example of an engine torque calculation process executed by the engine torque calculation device 10. The process illustrated in FIG. 14 may be executed for each sampling rate of the sample value acquisition unit 111, for example. During the processing shown in FIG. 14, the sensor output of the crank angle sensor 4 is continuously input to the engine torque calculation device 10.

  In step S <b> 100, the sample value acquisition unit 111 acquires the sampling value of the current sampling period with respect to the sensor output, and stores it in the sample value storage unit 114.

  In step S102, the cross time calculation unit 120 determines whether the sampling value acquired by the sample value acquisition unit 111 in step S100 crosses the predetermined reference value Vref in the positive direction. For example, if the previous sampling value is less than the predetermined reference value Vref but the current sampling value is larger than the predetermined reference value Vref, the cross time calculation unit 120 causes the sampling value to move the predetermined reference value Vref in the positive direction. Judge that crossed. If the determination result is “YES”, the process proceeds to step S104, and if the determination result is “NO”, the processing of the current cycle is terminated as it is.

  In step S104, the cross time point calculation unit 120 takes out the sampling values at the two most recent time points in the sample value storage unit 114, and calculates the cross time point based on the taken sampling values at the two time points. The calculation method of the crossing time is as described above. The cross time point calculation unit 120 stores the calculated cross time point in the cross time point storage unit 122.

  In step S106, the crank angular speed calculation unit 123 extracts the two most recent cross time points from the cross time point storage unit 122, and calculates the crank angular speed based on the two latest cross time points that have been extracted and the pitch angle Δθ (known). calculate. The method for calculating the crank angular velocity is as described above. The crank angular speed calculation unit 123 stores the calculated crank angular speed in the crank angular speed storage unit 124.

  In step S108, the crank angular acceleration calculation unit 130 determines the crank angle based on the crank angular velocities for the two most recent calculation cycles in the crank angular velocity storage unit 124 and the two most recent cross points in the cross point storage unit 122. Calculate acceleration. The method for calculating the crank angular acceleration is as described above.

  In step S110, the engine torque calculation unit 160 calculates the indicated torque based on the crank angular acceleration calculated in step S108. The method for calculating the indicated torque is as described above.

  In this way, according to the processing shown in FIG. 14, the current indicated torque can be accurately calculated every time the sensor output exceeds the predetermined reference value Vref (that is, every time the cross time occurs). Such an engine torque calculation device 10 can calculate the indicated torque with high accuracy in real time, and thus can be effectively used to improve the performance of the engine control system.

  By the way, in an engine control system of torque-based control, generally, a necessary net torque is determined by a driver's accelerator operation or the like, and a target value of the indicated torque that provides the net torque is set. At this time, in an actual vehicle, in order to feedback control the driving torque of the vehicle according to a target value, it is conceivable to measure the current indicated torque using an in-cylinder pressure sensor. However, installation of the in-cylinder pressure sensor is currently difficult because it causes problems of cost, durability, and maintainability.

  In this regard, according to the first embodiment, the indicated torque can be calculated with high accuracy by the engine torque calculation device 10 without installing an in-cylinder pressure sensor. Therefore, the engine torque calculation device 10 is effective for improving the performance of the engine control system. Available to:

In the first embodiment, as described above, the cross time point calculation unit 120 calculates the cross time point based on the sampling values at two time points sandwiching the predetermined reference value Vref. However, the present invention is not limited to this. For example, the cross time point calculation unit 120 may calculate the cross time point based on sampling values at three time points or more obtained by adding other sampling values to sampling values at two time points sandwiching the predetermined reference value Vref. In this case, the cross time point calculation unit 120 obtains an approximate straight line for sampling points at three or more time points by, for example, the least square method or the like, and based on the intersection of the approximate straight line and a straight line (slope 0) representing the predetermined reference value Vref. Thus, the cross time point may be calculated. In this case, the sampling points at three or more time points used for the calculation of the approximate straight line are preferably sampling points in the upstream section. This is the sampling value of the sensor output before rising from the minimum voltage V _MIN and the sampling value of the sensor output after reaching the maximum voltage V _MAX are the sampling values when the sensor output is not substantially changed, This is because the calculation accuracy of the time change rate β is deteriorated.

In the first embodiment, as described above, the cross time calculation unit 120 uses the sampling values immediately before and after the predetermined reference value Vref as the sampling values at the two time points sandwiching the predetermined reference value Vref. It is not limited to this. For example, the sampling values at the two time points used for the calculation of the cross time point are arbitrary as long as they are the sampling values at the two time points in the upstream section. Therefore, for example, the sampling value at two time points used for calculating the cross time point is a sampling value at any two time points after the sensor output rises from the minimum voltage V _MIN and before the predetermined reference value Vref. There may be. Similarly, the sampling values at the two time points used for the calculation of the cross time point are sampling values at any two time points after the sensor output exceeds the predetermined reference value Vref and before the maximum voltage V _MAX is reached. May be.

In the first embodiment, as described above, the cross time point calculation unit 120 calculates the cross time point based on the sampling values at the two time points in the uplink section, but is not limited thereto. That is, the cross time point calculation unit 120 may calculate the cross time point based on sampling values at two time points in a section where the sensor output decreases (hereinafter also referred to as “downward section”). The term “in the downward interval” refers to an interval after the sensor output starts falling from the maximum voltage V _MAX and before reaching the minimum voltage V _MIN . For example, the cross time point calculation unit 120 may calculate the cross time point based on the sampling values at the two time points in the downstream section and the sampling values at the two time points sandwiching the predetermined reference value Vref.

In the first embodiment, as described above, the predetermined reference value Vref = (V _MAX + V _MIN ) / 2, but the present invention is not limited to this. For example, the predetermined reference value Vref is arbitrary as long as the relationship of V _MIN <Vref <V _MAX is satisfied. The predetermined reference value Vref = V _MAX (or Vref = V _MIN ) may be used, and this embodiment will be described as a second embodiment described later.

  Further, in the first embodiment, as described above, the timing of the crossing and the timing at which the crank angle is advanced by the pitch angle Δθ are the same, but the present invention is not limited to this as long as they are synchronized. For example, the time point before or after a fixed predetermined time with respect to the cross time point may be the same as the timing at which the crank angle is advanced by the pitch angle Δθ.

  FIG. 15 is a diagram illustrating an example of an engine control system including the engine torque calculation device 10.

  The engine control system 2 is mounted on a vehicle. As described above, the vehicle may be a vehicle using only the engine as a drive source, or may be a hybrid vehicle. The engine control system 2 includes a sensor group 8, an engine control device 30 (an example of an engine control unit), an engine 80, a crank angle sensor 4, and an engine torque calculation device 10.

  The sensor group 8 includes, for example, an accelerator opening sensor, a vehicle speed sensor, a radar sensor, an image sensor, and the like as various in-vehicle sensors other than the crank angle sensor 4.

  The engine control device 30 electronically controls the engine 80. The electronic control of the engine 80 may include, for example, electronic control of the opening degree of a throttle valve (that is, the throttle opening degree) disposed in the intake manifold of the engine 80, although not shown. In addition, electronic control of the engine 80 includes, for example, electronic control of the amount of fuel injected into the combustion chamber of the engine 80 and ignition timing, and electronic control of the phase of the intake camshaft that adjusts the valve opening / closing timing. May include.

  The engine control device 30 is formed by an electronic control unit (ECU) and may have a hardware configuration as shown in FIG. 2, for example. As shown in FIG. 15, the engine control device 30 includes a driver request driving force calculation unit 31, a driver assistance driving force calculation unit 32, a target driving force arbitration unit 33, and a feedback control unit 34. The driver request driving force calculation unit 31, the driver assistance driving force calculation unit 32, the target driving force arbitration unit 33, and the feedback control unit 34 can be realized by the CPU of the electronic control unit executing a program.

  The driver required driving force calculation unit 31 is based on the information from the vehicle speed sensor and the accelerator opening sensor, and the driver required driving force according to the vehicle speed and the accelerator opening (hereinafter referred to as “first required driving force”). Is calculated.

  The driver support driving force calculation unit 32 calculates a required driving force (hereinafter referred to as “second required driving force”) for assisting the driver in driving the vehicle based on information from a radar sensor or the like. . The second required driving force is, for example, a driving force required to travel at a predetermined vehicle speed, a driving force required to follow the preceding vehicle, a driving force for limiting the vehicle speed so as not to exceed the limit vehicle speed, and the like. It's okay.

  The target driving force arbitration unit 33 selects either the first required driving force or the second required driving force according to a predetermined rule. For example, during the execution of ACC (Adaptive Cruse Control), the target driving force arbitration unit 33 selects the second required driving force while the first required driving force is 0, and the first required driving force exceeds the predetermined threshold. When it becomes larger, the first required driving force is selected. The target driving force arbitration unit 33 converts the selected requested driving force into a torque expression [N · m], and provides it to the feedback control unit 34 as the requested driving torque.

  For example, the feedback control unit 34 realizes the required driving torque based on the difference between the required driving torque given from the target driving force arbitration unit 33 and the calculated value of the indicated torque given from the engine torque calculating device 10. Alternatively, the control target value of the engine 80 may be determined. The engine control target value may be, for example, a throttle opening target value, a fuel injection amount target value, or the like. Note that equivalently, a calculated value of the net torque based on the calculated value of the indicated torque may be used instead of the calculated value of the indicated torque. For example, the net torque can be calculated by subtracting the engine friction torque from the calculated value of the indicated torque. The engine friction torque can be calculated based on, for example, the engine speed and load. Further, the feedback control unit 34 may determine the target value of the ignition timing as the engine control target value based on the calculated value of the indicated torque supplied from the engine torque calculation device 10. The feedback control unit 34 controls the engine 80 so that the determined control target value is realized.

  According to the engine control system 2 shown in FIG. 15, the engine torque calculation device 10 is provided, and the engine 80 can be feedback-controlled based on the difference between the required driving force and the calculated value of the indicated torque. Since the calculation accuracy of the calculated value of the indicated torque from the engine torque calculation device 10 is high as described above, the driving torque of the engine 80 can be controlled with high accuracy. Thereby, for example, it is not necessary to inject fuel excessively into the cylinder, engine performance is improved, and fuel consumption and drivability are improved. In this way, the engine torque calculation device 10 can be effectively used for improving the performance of the engine control system.

  In the example illustrated in FIG. 15, the engine torque calculation device 10 is provided separately from the engine control device 30, but is not limited thereto. A part or all of the functions of the engine torque calculation device 10 may be realized by the engine control device 30.

  In the example shown in FIG. 15, the engine control system 2 controls the engine 80 using the calculation result by the engine torque calculation device 10, but is not limited thereto. For example, the calculation result by the engine torque calculation device 10 can be used for control of a vehicle drive device (for example, a transmission, an electric motor, a clutch, etc.) other than the engine 80. This is because the control target value of the vehicle drive device other than the engine 80 (for example, the target gear stage of the transmission) may be related to the control target value of the engine 80.

  In the example illustrated in FIG. 15, the engine control system 2 includes the driver assistance driving force calculation unit 32, but the driver assistance driving force calculation unit 32 may be omitted. In this case, the target driving force arbitration unit 33 is also unnecessary, and the feedback control unit 34 may always use the first required driving force from the driver required driving force calculation unit 31.

[Example 2]
Example 2, point a predetermined reference value Vref is the maximum voltage _{V MAX} is different from Embodiment 1 described above. The engine torque calculation device 10A according to the second embodiment may have the same hardware configuration as the engine torque calculation device 10 according to the first embodiment described above, but the functions are different as follows.

  FIG. 16 is a functional block diagram of the engine torque calculation device 10A. The engine torque calculation device 10A according to the second embodiment is mainly different from the engine torque calculation device 10 according to the first embodiment described above in the following points. The cross time point calculation unit 120 and the cross time point storage unit 122 are replaced with a maximum arrival time point calculation unit 140 (an example of a reference time point calculation unit) and a maximum arrival time point storage unit 141, respectively. In addition, the crank angle calculation unit 121, the crank angular speed calculation unit 123, and the crank angular acceleration calculation unit 130 are replaced with a crank angle calculation unit 121A, a crank angular speed calculation unit 123A, and a crank angular acceleration calculation unit 130A, respectively. The other components may be substantially the same as those of the engine torque calculation device 10 according to the first embodiment described above, and in FIG. The maximum reaching point calculation unit 140, the crank angle calculation unit 121A, the crank angular velocity calculation unit 123A, and the crank angular acceleration calculation unit 130A can be realized by causing the control unit 101 to execute a program in the main storage unit 102. Further, the maximum arrival time storage unit 141 can be realized by the RAM of the main storage unit 102, for example.

The maximum arrival time point calculation unit 140 is based on the sampling values at the two time points in the upward section, and the maximum arrival time point (rising edge time point) when the sensor output becomes the predetermined reference value Vref (= maximum voltage V _MAX ). Is calculated. The maximum arrival time calculation unit 140 stores the calculated maximum arrival time in the maximum arrival time storage unit 141.

In the second embodiment, as an example, the maximum arrival time point calculation unit 140 is a sampling value at two time points in the upstream section, and sampling at two time points sandwiching an intermediate value (= (V _MAX + V _MIN ) / 2). Based on the value, the maximum arrival time is calculated. For example, the maximum arrival time point calculation unit 140 determines that the most recent 2 in the sample value storage unit 114 when the sampling value stored most recently in the sample value storage unit 114 exceeds the intermediate value from a state of being less than the intermediate value. The sampling value at the time is taken out. Then, the maximum arrival time point calculation unit 140 calculates the maximum arrival time point based on the extracted sampling values at the two time points.

  FIG. 17 is an explanatory diagram of a method for calculating the maximum arrival time by the maximum arrival time calculation unit 140. In FIG. 17, the horizontal axis represents time, the vertical axis represents voltage, and a sensor output waveform 70 is shown. In FIG. 17, sampling points s (n−3) to s (n + 2) obtained at the period i (= n−3 to n + 2) are indicated by ◯.

Specifically, the maximum arrival time point calculation unit 140 calculates the time change rate β of the sensor output between the two time points based on the difference ΔV between the sampling values at the two time points and the time dt between the two time points. To do. In FIG. 17, the difference between the sampling values at two time points is ΔV, and ΔV = v (n) −v (n−1). The time dt between the two time points corresponds to the sampling rate. Therefore, the time change rate β of the sensor output between the two time points is β = ΔV / dt = (v (n) −v (n−1)) / dt. Then, the maximum arrival time point calculation unit 140 calculates the maximum arrival time point tp based on the calculated time change rate β. For example, the maximum arrival time tp can be calculated as follows with respect to the time t (n−1).
tp = (Vref−v (n−1)) / β + t (n−1)
Alternatively, the maximum arrival time tp can be calculated as follows with respect to the time t (n).
tp = (Vref−v (n)) / β + t (n)
This calculation method is suitable when the sensor output changes linearly between the maximum voltage V _MAX and the minimum voltage V _MIN as shown in FIG. In other words, this calculation method assumes that the sensor output changes at a constant time change rate between the maximum voltage V _MAX and the minimum voltage V _MIN , and the rising edge point P ₂ at which the sensor output becomes the predetermined reference value Vref (FIG. 17). Therefore, the maximum rising edge point _{P 2} according to the arrival time tp is the sampling point s (n-1) a straight line connecting the sampling points s (n) (slope beta), the predetermined reference value Vref (= maximum voltage V _MAX ) is a crossing point with a straight line (inclination is 0).

  Note that the maximum arrival time is synchronized with the timing at which the crank angle is advanced by the pitch angle Δθ, similar to the cross time in the first embodiment.

  The maximum arrival time storage unit 141 has a storage area for storing the maximum arrival time calculated by the maximum arrival time calculation unit 140. The storage area has a capacity for storing, for example, the latest predetermined number of maximum arrival points or more. The maximum arrival time storage unit 141 is, for example, a ring buffer, and holds the latest maximum number of maximum arrival times in the FIFO format. The predetermined number is, for example, 2 although it depends on the calculation method in the crank angular velocity calculation unit 123 and the crank angular acceleration calculation unit 130.

  The crank angle calculation unit 121A calculates the crank angle at the maximum reaching point based on the maximum reaching point calculated by the maximum reaching point calculating unit 140. In the second embodiment, as an example, the maximum reaching point is set to a timing at which the crank angle is advanced by the pitch angle Δθ. Therefore, the crank angle at the current maximum arrival time can be calculated by adding the pitch angle Δθ to the crank angle at the previous maximum arrival time.

  The crank angular velocity calculation unit 123A calculates the crank angular velocity based on the maximum reaching point calculated by the maximum reaching point calculating unit 140. The calculation method of the crank angular velocity is substantially the same as the calculation method by the crank angular velocity calculation unit 123 according to the first embodiment described above, except that the “cross time” is replaced with the “maximum arrival time”. Description is omitted.

  The crank angular acceleration calculation unit 130A calculates the crank angular acceleration based on the maximum arrival time calculated by the maximum arrival time calculation unit 140 and the crank angular velocity calculated by the crank angular speed calculation unit 123A. The calculation method of the crank angular acceleration is substantially the same as the calculation method by the crank angular acceleration calculation unit 130 according to the first embodiment described above, except that the “cross time” is replaced with the “maximum arrival time”. Further explanation is omitted.

  According to the second embodiment, the same effect as the first embodiment can be obtained. That is, assuming that the actual time when the sensor output becomes the predetermined reference value Vref is “true value”, according to the second embodiment, the maximum arrival time with respect to the true value (maximum arrival time calculated by the maximum arrival time calculation unit 140). It can be suppressed that the shift of the fluctuation fluctuates relatively between the calculation cycles. Specifically, according to the second embodiment, as described above, the maximum arrival time is calculated based on the sampling values at the two time points in the upstream section for each calculation cycle. Since the maximum arrival time is calculated based on the time change rate β of the sensor output between the two time points in the upstream section as described above, it matches the true value with high accuracy for each calculation cycle. As a result, it is possible to prevent the deviation of the maximum arrival time from the true value from fluctuating relatively greatly between the calculation cycles. Therefore, according to the second embodiment, it is possible to improve the calculation accuracy of the crank angular velocity.

  Next, an operation example of the engine torque calculation device 10A will be described with reference to FIG.

  FIG. 18 is a flowchart illustrating an example of an engine torque calculation process executed by the engine torque calculation device 10A. The process illustrated in FIG. 18 may be executed for each sampling rate of the sample value acquisition unit 111, for example. During the processing shown in FIG. 18, the sensor output of the crank angle sensor 4 is continuously input to the engine torque calculation device 10A.

  Step S200 and step S210 may be the same as step S100 and step S110 of FIG.

In step S202, the maximum arrival time point calculation unit 140 determines whether or not the sampling value acquired by the sample value acquisition unit 111 in step S200 exceeds the intermediate value (= (V _MAX + V _MIN ) / 2). If the determination result is “YES”, the process proceeds to step S204. If the determination result is “NO”, the processing of the current cycle is terminated as it is.

  In step S204, the maximum reaching time point calculation unit 140 takes out the sampling values at the two most recent time points in the sample value storage unit 114, and calculates the maximum reaching time point based on the extracted sampling values at the two time points. The method for calculating the maximum arrival time is as described above. The maximum arrival time calculation unit 140 stores the calculated maximum arrival time in the maximum arrival time storage unit 141.

  In step S206, the crank angular velocity calculation unit 123A extracts the two latest maximum arrival points from the maximum arrival point storage unit 141, and based on the two latest maximum arrival points and the pitch angle Δθ (known). Calculate the crank angular velocity. The method for calculating the crank angular velocity is as described above. The crank angular velocity calculation unit 123A stores the calculated crank angular velocity in the crank angular velocity storage unit 124.

  In step S208, the crank angular acceleration calculation unit 130A is based on the crank angular velocities for the two most recent calculation cycles in the crank angular velocity storage unit 124 and the two latest maximum arrival points in the maximum arrival point storage unit 141. Crank angular acceleration is calculated. The method for calculating the crank angular acceleration is as described above.

  In this way, according to the processing shown in FIG. 18, the current indicated torque can be accurately calculated every time the sensor output exceeds the intermediate value (that is, every time the up section occurs). Such an engine torque calculation device 10A can calculate the indicated torque with high accuracy in real time, and thus can be effectively used to improve the performance of the engine control system. For example, the engine torque calculation device 10A according to the second embodiment can function similarly in place of the engine torque calculation device 10 (the engine torque calculation device 10 according to the first embodiment) of the engine control system 2 shown in FIG.

In the second embodiment, as described above, the maximum arrival time point calculation unit 140 calculates the maximum arrival time point based on the sampling values at the two time points with the intermediate value interposed therebetween, but the present invention is not limited to this. For example, the maximum reaching time point calculation unit 140 may calculate the maximum reaching time point based on sampling values at three or more time points obtained by adding other sampling values to sampling values at two time points with the intermediate value interposed therebetween. In this case, the maximum reaching time point calculation unit 140 obtains an approximate line for sampling points at three or more time points by, for example, the least square method, and the straight line representing the approximate line and a predetermined reference value Vref (= maximum voltage V _MAX ) ( The maximum arrival time may be calculated based on the intersection with the slope 0). In this case, the sampling points at three or more time points used for the calculation of the approximate straight line are preferably sampling points in the upstream section.

In the second embodiment, as described above, the maximum arrival time point calculation unit 140 uses the sampling values immediately before and immediately after the intermediate value as sampling values at two time points sandwiching the intermediate value. I can't. For example, the sampling values at the two time points used for the calculation of the maximum reaching time point are arbitrary as long as they are the sampling values at the two time points in the upstream section. Therefore, for example, the sampling values at the two time points used for calculating the maximum reaching time point are sampling values at any two time points after the sensor output rises from the minimum voltage V _MIN and before the intermediate value is exceeded. May be. Similarly, the sampling value at the two time points used for calculating the maximum reaching time point is a sampling value at any two time points after the sensor output exceeds the intermediate value and before reaching the maximum voltage V _MAX. Also good.

In the second embodiment, as described above, the predetermined reference value Vref is the maximum voltage V _MAX . However, the present invention is not limited to this. That is, the predetermined reference value Vref may be the minimum voltage _VMIN . In this case, the maximum arrival time calculating unit 140 replaces the maximum arrival time with the sensor output at the predetermined reference value Vref (= minimum voltage V _MIN ) based on the sampling values at the two time points in the downstream section. A certain minimum arrival time may be calculated. For example, the maximum arrival time point calculation unit 140 may calculate the minimum arrival time point based on the sampling values at two time points in the downlink section and the sampling values at two time points with the intermediate value interposed therebetween.

In the second embodiment, as described above, the intermediate value = (V _MAX + V _MIN ) / 2 is used, but the present invention is not limited to this. For example, instead of the intermediate value, another predetermined value that satisfies the relationship of V _MIN <Vth <V _MAX may be used.

  In the second embodiment, as described above, the maximum reaching point and the timing at which the crank angle is advanced by the pitch angle Δθ are the same, but this is not limited as long as they are synchronized. For example, the time point before or after a fixed predetermined time with respect to the maximum arrival time point and the timing at which the crank angle is advanced by the pitch angle Δθ may be the same.

[Example 3]
The third embodiment is different from the first embodiment described above in that the crank angular velocity is calculated based on the cross points calculated in both the up and down sections. The engine torque calculation device 10B according to the third embodiment may have the same hardware configuration as the engine torque calculation device 10 according to the first embodiment described above, but the functions are different as follows.

  FIG. 19 is a functional block diagram of the engine torque calculation device 10B. The engine torque calculation device 10B according to the third embodiment is mainly different from the engine torque calculation device 10 according to the first embodiment described above in the following points. A second cross time calculation unit 142 is added. In addition, the crank angular velocity calculation unit 123, the crank angular acceleration calculation unit 130, and the engine torque calculation unit 160 are replaced with a crank angular velocity calculation unit 123B, a crank angular acceleration calculation unit 130B, and an engine torque calculation unit 160B, respectively. Other components may be substantially the same as those of the engine torque calculation device 10 according to the first embodiment described above, and the same reference numerals are given in FIG. The second cross point calculation unit 142, the cross point storage unit 122B, the crank angular velocity calculation unit 123B, and the crank angular acceleration calculation unit 130B can be realized by the control unit 101 executing a program in the main storage unit 102. In the third embodiment, the cross time point calculation unit 120 and the second cross time point calculation unit 142 form an example of a reference time point calculation unit.

  The second cross time point calculation unit 142 calculates the time point at which the sensor output becomes the predetermined reference value Vref based on the sampling values at the two time points in the downward section.

In the third embodiment, as an example, the second cross time point calculation unit 142 calculates the sensor output based on the sampling values at the two time points in the downstream section and the sampling values at the two time points sandwiching the predetermined reference value Vref. A crossing time point that is a time point when the predetermined reference value Vref is crossed is calculated. Hereinafter, when distinguishing, the cross time point calculated by the cross time point calculation unit 120 as described above is referred to as “upward cross time point”, and the cross time point calculated by the second cross time point calculation unit 142 is referred to as “down cross time point”. ". In the third embodiment, as an example, the predetermined reference value Vref is the predetermined reference value Vref = (V _MAX + V _MIN ) / 2 as in the first embodiment.

  For example, the second cross time point calculation unit 142 stores the sample value stored in the sample value storage unit 114 when the sampling value most recently stored in the sample value storage unit 114 falls below the predetermined reference value Vref from a state where it is greater than the predetermined reference value Vref. The sampling values at the two most recent time points are taken out. Then, the second cross time point calculation unit 142 calculates the downlink cross time point based on the extracted sampling values at the two time points. The second cross time point calculation unit 142 stores the calculated down cross time point in the cross time point storage unit 122.

  The crank angular speed calculation unit 123B calculates the crank angular speed based on the up cross time calculated by the cross time calculation unit 120 and the crank angular speed based on the down cross time calculated by the second cross time calculation unit 142. Is calculated. The method of calculating the crank angular speed based on the up crossing time is as described above. The method for calculating the crank angular speed based on the down cross time is substantially the same as the method for calculating the crank angular speed based on the up cross time, and therefore the description will be simplified. Specifically, the crank angular velocity calculation unit 123B calculates the crank angular velocity based on the time between two adjacent down cross points on the time axis and the pitch angle Δθ in the non-missing tooth section. Hereinafter, when distinguishing, the crank angular speed calculated based on the up cross point is referred to as “first crank angular speed”, and the crank angular speed calculated based on the down cross point is referred to as “second crank angular speed”.

  20 and 21 are explanatory diagrams of the first crank angular speed and the second crank angular speed calculated by the crank angular speed calculation unit 123B. In FIG. 20, the up cross time points tu1 to tu5 and the first crank angular velocities ωu1 to ωu5 calculated correspondingly are shown on the upper side of the sensor output 70. Further, in FIG. 20, the down cross points td <b> 1 to td <b> 5 and the second crank angular velocities ωd <b> 1 to ωd <b> 5 calculated corresponding to the respective points are shown below the sensor output 70. In FIG. 21, time is plotted on the horizontal axis, crank angular velocity is plotted on the vertical axis, and time series of calculation results of the first crank angular velocity and the second crank angular velocity are shown. Specifically, the first crank angular speeds ωu2 to ωu8 calculated corresponding to the up crossing times t2 to tu8, and the second crank angular speeds calculated corresponding to the down crossing times td2 to td8, respectively. ωd2 to ωd8 are shown.

  The crank angular acceleration calculation unit 130B calculates the crank angular acceleration based on the crank angular velocity calculated by the crank angular velocity calculation unit 123B. The crank angular acceleration calculation unit 130B calculates the crank angular acceleration based on the first crank angular velocity for the two most recent calculation cycles from the crank angular velocity storage unit 124 and the two most recent up cross points from the cross point storage unit 122. To do. Further, the crank angular acceleration calculation unit 130B determines the crank angular acceleration based on the second crank angular velocity for the two most recent calculation cycles from the crank angular velocity storage unit 124 and the two most recent down cross points from the cross point storage unit 122. Is calculated. The method for calculating the crank angular acceleration is as described above. Hereinafter, when distinguishing, the crank angular acceleration calculated based on the up cross point is referred to as “first crank angular acceleration”, and the crank angular acceleration calculated based on the down cross point is referred to as “second crank angular acceleration”. Called.

  The engine torque calculation unit 160B calculates engine torque based on the crank angular acceleration calculated by the crank angular acceleration calculation unit 130B. Specifically, when the first crank angular acceleration is calculated by the crank angular velocity calculating unit 123B, the engine torque calculating unit 160B calculates the indicated torque based on the first crank angular acceleration. Further, when the second crank angular acceleration is calculated by the crank angular velocity calculating unit 123B, the engine torque calculating unit 160B calculates the indicated torque based on the second crank angular acceleration. The method for calculating the indicated torque from the crank angular acceleration is as described above.

  FIG. 22 is a flowchart illustrating an example of an engine torque calculation process executed by the engine torque calculation device 10B. The process illustrated in FIG. 22 may be executed for each sampling rate of the sample value acquisition unit 111, for example. During the process shown in FIG. 22, the sensor output of the crank angle sensor 4 is continuously input to the engine torque calculation device 10B.

  The processing from step S100 to step S110 is as described in FIG. However, if the determination result is “YES” in step S102, the process proceeds to step S104, and if the determination result is “NO”, the process proceeds to step S302.

  In step S302, the second cross time point calculation unit 142 determines whether or not the sampling value acquired by the sample value acquisition unit 111 in step S100 crosses the predetermined reference value Vref in the negative direction. For example, if the previous sampling value is larger than the predetermined reference value Vref but the current sampling value is less than the predetermined reference value Vref, the second cross time point calculation unit 142 makes the sampling value negative with respect to the predetermined reference value Vref. Judged to cross in the direction. When the determination result is “YES”, the process proceeds to step S304, and when the determination result is “NO”, the processing of the current cycle is ended as it is.

  In step S304, the second cross time point calculation unit 142 extracts the sampling values at the two most recent time points in the sample value storage unit 114, and calculates the down cross time point based on the sampled values at the two time points. The method of calculating the downlink crossing time is as described above. The second cross time point calculation unit 142 stores the calculated down cross time point in the cross time point storage unit 122.

  In step S306, the crank angular velocity calculation unit 123B extracts the two most recent down cross points from the cross point storage unit 122, and based on the two most recent down cross points extracted and the pitch angle Δθ (known). 2Crank angular velocity is calculated. The calculation method of the second crank angular velocity is as described above. The crank angular velocity calculation unit 123B stores the calculated second crank angular velocity in the crank angular velocity storage unit 124.

  In step S308, the crank angular acceleration calculation unit 130B is based on the second crank angular velocity for the two most recent calculation cycles in the crank angular velocity storage unit 124 and the two most recent down cross points in the cross point storage unit 122. The second crank angular acceleration is calculated. The calculation method of the second crank angular acceleration is as described above.

  In step S310, the engine torque calculation unit 160B calculates the indicated torque based on the second crank angular acceleration calculated in step S308. The method for calculating the indicated torque is as described above.

  In this way, according to the processing shown in FIG. 22, every time the sensor output exceeds the predetermined reference value Vref (that is, every time the up crossing point occurs) and every time the sensor output falls below the predetermined reference value Vref ( That is, the current indicated torque can be calculated with high accuracy every time a down crossing occurs. Thereby, for example, the indicated torque can be accurately calculated in a short period in real time without increasing the sampling rate more than necessary. Such an engine torque calculation device 10 can calculate the indicated torque with high accuracy in real time, and thus can be effectively used to improve the performance of the engine control system. For example, the engine torque calculation device 10B according to the third embodiment can function similarly instead of the engine torque calculation device 10 (the engine torque calculation device 10 according to the first embodiment) of the engine control system 2 illustrated in FIG.

  In the third embodiment, as described above, the second cross time point calculation unit 142 calculates the down cross time point based on the sampling values at the two time points across the predetermined reference value Vref, but the present invention is not limited to this. . For example, the second cross time point calculation unit 142 calculates the down cross time point based on the sampling values at three time points or more obtained by adding other sampling values to the sampling values at two time points sandwiching the predetermined reference value Vref. Also good. In this case, the sampling points at three or more time points used for calculation of the downlink cross time are preferably sampling points in the downlink interval.

In the third embodiment, as described above, the second cross time point calculation unit 142 uses the sampling values immediately before and after the predetermined reference value Vref as the sampling values at the two time points sandwiching the predetermined reference value Vref. However, it is not limited to this. For example, the sampling values at the two time points used for the calculation of the downlink cross time are arbitrary as long as they are the sampling values at the two time points in the downlink section. Therefore, for example, the sampling values at the two time points used for the calculation of the down cross time point are the values at any two time points after the sensor output starts to drop from the maximum voltage V _MAX and before it falls below the predetermined reference value Vref. It may be a sampling value. Similarly, the sampling values at two time points used for the calculation of the down cross time point are sampling values at any two time points after the sensor output falls below the predetermined reference value Vref and before reaching the minimum voltage _VMIN. There may be.

  In the third embodiment, as described above, the crank angular acceleration calculation unit 130B uses the first and second crank angular accelerations independently (separately) at the up cross time and the down cross time. However, the present invention is not limited to this. For example, the crank angular acceleration calculation unit 130B may calculate the crank angular acceleration based on the most recent combination of the first and second crank angular velocities and the most recent combination of the up cross time and the down cross time.

[Example 4]
The fourth embodiment is different from the first embodiment described above in that the crank angular velocity is calculated based on the sensor output of the crank angle sensor 4C whose amplitude can change according to the engine speed or the like. Specifically, in the first embodiment described above, the sensor output periodically fluctuates between the fixed maximum voltage V _MAX and the fixed minimum voltage V _MIN , but in the fourth embodiment, the sensor output is the maximum The voltage and minimum voltage can vary. The crank angle sensor 4C having such sensor output characteristics is, for example, an electromagnetic pickup (MPU) type.

  FIG. 23 is an explanatory diagram of an electromagnetic pickup type crank angle sensor 4C. FIG. 23 shows the crank angle sensor 4C in a schematic cross-sectional view, and the crank rotor 5 in relation to the crank angle sensor 4C. The crank angle sensor 4 </ b> C includes a detection coil 41, a magnet 42, and a pole piece 43. In the example shown in FIG. 23, the crank rotor 5 is a magnetic involute gear. When the crank rotor 5 rotates, the tooth portion of the crank rotor 5, which is a magnetic material, repeats approaching and leaving the pole piece 43. Along with this, the state of the magnetic path formed by the magnet 42 and the pole piece 43 changes, and the magnetic flux penetrating the detection coil 41 changes. Specifically, with the rotation of the crank rotor 5, the magnetic flux penetrating the detection coil 41 increases when the teeth of the crank rotor 5 approach the pole piece 43, and the detection coil 41 when the teeth of the crank rotor 5 move away from the pole piece 43. The state that the magnetic flux penetrating the magnetic head decreases is repeated. The induced electromotive force V generated in the detection coil 41 is as follows.

ここで、Ｎはコイルの巻き数であり、φ_ｍは検出コイル４１を貫通する磁束である。誘導起電力Ｖは、クランクロータ５の回転に伴い、図２４に示すように変化する。図２４に示すような誘導起電力Ｖの波形は、クランク角度センサ４のセンサ出力として取り出される。尚、図２４において、Ｙ１部は、クランクロータ５の欠歯部に起因した波形特徴を示す。センサ出力は、図２４に示すように、クランク角度0〜720ＣＡの区間において、クランクシャフトの回転に伴い周期的に０を跨いで（即ち０Ｖをクロスして）振幅の最大点及び最小点が発生する区間と、上死点検出用の欠歯区間とを含む。尚、非欠歯区間においては、センサ出力が０Ｖを負から正の方向（上り）にクロスする毎に、クランク角度がピッチ角Δθだけ進角することになる。

Here, N is the number of turns of the coil, and φ _m is a magnetic flux penetrating the detection coil 41. The induced electromotive force V changes as the crank rotor 5 rotates as shown in FIG. The waveform of the induced electromotive force V as shown in FIG. 24 is taken out as the sensor output of the crank angle sensor 4. In FIG. 24, a Y1 portion indicates a waveform characteristic caused by a missing tooth portion of the crank rotor 5. As shown in FIG. 24, the maximum and minimum points of the amplitude of the sensor output are generated across the period of 0 (that is, crossing 0V) with the rotation of the crankshaft in the section of the crank angle 0 to 720CA. And a missing tooth section for detecting the top dead center. In the non-missing tooth section, every time the sensor output crosses 0V from negative to positive (upward), the crank angle is advanced by the pitch angle Δθ.

  The engine torque calculation device 10C according to the fourth embodiment may have the same hardware configuration as the engine torque calculation device 10 according to the first embodiment described above, but the functions are different as follows.

  FIG. 25 is a functional block diagram of the engine torque calculation device 10C. The engine torque calculation device 10C according to the fourth embodiment is mainly different from the engine torque calculation device 10 according to the first embodiment described above in that the cross point calculation unit 120 is replaced with a cross point calculation unit 120C. Other constituent elements may be substantially the same as those of the engine torque calculation device 10 according to the first embodiment described above, and in FIG. The cross time calculation unit 120C can be realized by the control unit 101 executing a program in the main storage unit 102.

  The cross time point calculation unit 120C calculates the time point at which the sensor output becomes the predetermined reference value Vref based on the sampling values at two time points in the upstream section of the sensor output. The predetermined reference value Vref is arbitrary, but in the fourth embodiment, it is 0 [V] as an example. In the fourth embodiment, as an example, the cross time point calculation unit 120C calculates a cross time point, which is a time point when the sensor output crosses 0, based on sampling values at 2 time points across 0 in the upstream section of the sensor output. To do.

  FIG. 26 is an explanatory diagram of a cross time calculation method performed by the cross time calculation unit 120C. In FIG. 26, the horizontal axis represents time, the vertical axis represents voltage, and a sensor output waveform 70 is shown. In FIG. 26, sampling points s (n−3) to s (n + 2) obtained at the sampling period i (= n−3 to n + 2) are indicated by ◯. In the example shown in FIG. 26, the sampling values at two time points across the predetermined reference value Vref are the voltage value v (n−1) at the sampling point s (n−1) and the voltage value at the sampling point s (n). v (n).

Similar to the first embodiment described above, the cross time point calculation unit 120C uses the difference ΔV between the sampling values at the two time points and the time dt between the two time points, and the time change rate β of the sensor output between the two time points. Can be calculated. In FIG. 26, the difference ΔV between the sampling values at the two time points is ΔV = v (n) −v (n−1). Therefore, the time change rate β of the sensor output between the two time points is β = ΔV / dt = (v (n) −v (n−1)) / dt. Then, the cross time point calculation unit 120C can calculate the cross time point tc based on the calculated time change rate β as follows.
tc = (Vref−v (n−1)) / β + t (n−1)
In a modification, the cross time point calculation unit 120C may calculate a cross time point, which is a time point at which the sensor output crosses 0, based on sampling values at three or more time points in the upstream section of the sensor output. For example, in the example shown in FIG. 26, the sampling values at three or more time points in the upstream section of the sensor output are the voltage value v (n-1) at the sampling point s (n-1) and the sampling point s (n). And the voltage value v (n + 1) at the sampling point s (n + 1). In this case, the cross time point calculation unit 120C derives an approximate curve or an approximate line with respect to sampling points at three or more time points in the upstream section of the sensor output, and determines the cross time point based on the derived approximate curve or approximate line. It can be calculated. For example, Lagrange interpolation, spline interpolation, sinc function interpolation, or the like may be used to derive the approximate curve. According to the modification, it is possible to derive a crossing point with higher accuracy with respect to the true value than when the above-described time change rate β is used.

  According to the fourth embodiment, the same effects as those of the first embodiment described above can be obtained. In the fourth embodiment, an electromagnetic pickup type crank angle sensor 4C is used. However, for example, a crank angle sensor using a Hall element (a magnetic sensor using the Hall effect) may be used.

  Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope described in the claims. It is also possible to combine all or a plurality of the components of the above-described embodiments.

  For example, in the above-described first embodiment (the same applies to the second to fourth embodiments), the A / D converter 110 is provided in the engine torque calculation device 10, but the A / D converter 110 is a sensor including the crank angle sensor 4. It may be incorporated in the unit.

  In the first embodiment described above (the same applies to the second to fourth embodiments), the engine torque calculation device 10 is an example of an engine state parameter calculation device, and the engine state parameter to be calculated is the indicated torque. However, the engine state parameter to be calculated may be engine torque other than the indicated torque (for example, net torque, torque obtained by subtracting external load torque from the indicated torque, or the like). Alternatively, the engine state parameter to be calculated may be another parameter related to the engine torque (for example, crank angle, crank angular velocity, crank angular acceleration, etc.). For example, in the above-described first embodiment (the same applies to the second to fourth embodiments), a part of the engine torque calculation device 10 (for example, part X1 in FIG. 7) can be embodied as a crank angle calculation device. In this case, the crank angle calculation apparatus may generate a crank angle signal (Hi / Lo binary digital signal) that becomes a rising edge at the cross time calculated by the cross time calculation unit 120. In this case, the crank angle calculation device may be incorporated in a sensor unit including the crank angle sensor 4. Similarly, in the above-described first embodiment (the same applies to the second to fourth embodiments), a part of the engine torque calculation device 10 (for example, the X1 portion + X2 portion in FIG. 7) can be embodied as a crank angular velocity calculation device. Similarly, in the above-described first embodiment (the same applies to the second to fourth embodiments), a part of the engine torque calculation device 10 (for example, X1 portion + X2 portion + X3 portion in FIG. 7) is a crank angular acceleration calculation device. Can be embodied.

  Further, in the above-described first embodiment (the same applies to the second to fourth embodiments), a vehicle including an engine is targeted as an example. However, the target is arbitrary as long as the engine is included. For example, the target may be a railway vehicle equipped with an engine, a ship equipped with an engine, a construction machine equipped with an engine, a motorcycle equipped with an engine (a type of vehicle), an aircraft equipped with an engine, a helicopter equipped with an engine, and the like.

In addition, the following additional remarks are disclosed regarding the above Example.
(Appendix 1)
An acquisition unit that acquires sampling values at a plurality of times of sensor output of a crank angle sensor provided for the crankshaft of the engine;
A reference time point calculation unit that calculates a reference time point that is a time point at which the sensor output becomes a predetermined reference value based on the sampling values at two time points within a section in which the sensor output increases or decreases;
An engine condition parameter calculation device comprising: a parameter calculation unit that calculates a parameter that represents an engine state based on the reference time point calculated by the reference time point calculation unit.
(Appendix 2)
The engine state parameter calculation device according to appendix 1, wherein the parameter includes at least one of a crank angle, a crank angular velocity, a crank angular acceleration, and an engine torque.
(Appendix 3)
The reference time point calculation unit calculates a time change rate of the sensor output between the two time points based on the difference between the sampling values at the two time points and the time between the two time points, and the time The engine state parameter calculation device according to attachment 1 or 2, wherein the reference time point is calculated based on a change rate.
(Appendix 4)
The reference time point calculation unit calculates the time obtained by dividing the difference between the sampling value at one of the two time points and the predetermined reference value by the time change rate, and the one time point and the reference time point. The engine condition parameter calculation device according to attachment 3, wherein the reference time point is calculated so as to coincide with a time between the time points.
(Appendix 5)
The sampling value at the two time points sandwiches a predetermined value, and the predetermined value is less than the maximum value of the sensor output and larger than the minimum value of the sensor output. The engine state parameter calculation device described.
(Appendix 6)
6. The engine condition parameter calculation device according to appendix 5, wherein the predetermined value is equal to the predetermined reference value.
(Appendix 7)
The engine condition parameter calculation apparatus according to appendix 1 or 2, wherein the reference time point calculation unit calculates the reference time point based on the sampling values at three or more time points in the section including the two time points.
(Appendix 8)
The reference time point calculation unit derives an approximate curve or approximate line of the sensor output in the section based on the sampling values of the three time points or more, and determines the reference time point based on the approximate curve or approximate line. The engine state parameter calculation device according to appendix 7, which calculates.
(Appendix 9)
The sensor output includes a first section that rises and falls every predetermined pitch angle as the crankshaft rotates, and a second section for detecting top dead center,
In the first section, the parameter calculation unit calculates the parameter based on a time between two reference time points adjacent on the time axis and the predetermined pitch angle. The engine condition parameter calculation device according to any one of the above.
(Appendix 10)
The reference time point calculated by the reference time point calculation unit is at least one of a first reference time point in an ascending section where the sensor output increases and a second reference time point in a descending section where the sensor output decreases. The engine condition parameter calculation device according to any one of supplementary notes 1 to 9, wherein
(Appendix 11)
The reference time point calculated by the reference time point calculation unit includes the first reference time point and the second reference time point,
The engine state parameter calculation device according to appendix 10, wherein the parameters include a first crank angular speed based on the first reference time point and a second crank angular speed based on the second reference time point.
(Appendix 12)
The acquisition unit according to any one of appendices 1 to 11, wherein the acquisition unit acquires the sampling values at a plurality of time points by sampling the sensor output at a predetermined sampling rate via an A / D converter. Engine condition parameter calculation device.
(Appendix 13)
The sensor output varies between a fixed maximum value and a fixed minimum value,
The engine condition parameter calculation device according to any one of appendices 1 to 12, wherein the sampling value used for calculation of the reference time point is smaller than the maximum value and larger than the minimum value.
(Appendix 14)
In the two-dimensional coordinate system having time and the sensor output as two axes, the reference time point calculation unit passes through a point determined by one of the two time points and the sampling value at the one time point. The engine condition parameter calculation apparatus according to appendix 3, wherein the reference time point is calculated based on the coordinates of an intersection point at which a straight line having an inclination with the time change rate intersects with a straight line representing the predetermined reference value.
(Appendix 15)
The sensor output varies between a fixed maximum value and a fixed minimum value,
The predetermined reference value is less than the maximum value and greater than the minimum value;
The engine state parameter calculation device according to any one of appendices 1 to 4, wherein the sampling values at the two time points sandwich the predetermined reference value.
(Appendix 16)
Obtain sampling values at multiple time points of the sensor output of the crank angle sensor provided for the crankshaft of the engine,
Based on the sampling values at two time points in the interval in which the sensor output increases or decreases, a reference time point that is a time point when the sensor output becomes a predetermined reference value is calculated,
A computer-implemented engine condition parameter calculation method comprising calculating a parameter representing an engine condition based on the reference time point.
(Appendix 17)
Engine,
A crank angle sensor provided for the crankshaft of the engine;
An acquisition unit for acquiring sampling values at a plurality of time points of the sensor output of the crank angle sensor;
A reference time point calculation unit that calculates a reference time point that is a time point at which the sensor output becomes a predetermined reference value based on the sampling values at two time points within a section in which the sensor output increases or decreases;
An engine control system including an engine control unit that controls the engine based on the reference time point calculated by the reference time point calculation unit.

DESCRIPTION OF SYMBOLS 1 Engine torque calculation system 2 Engine control system 4, 4C Crank angle sensor 5 Crank rotor 5a Toothless part 5b Projection 6 Crankshaft 8 Sensor group 10, 10A, 10B, 10C Engine torque calculation device 30 Engine control device 31 Driver demand drive Force calculation unit 32 Driver support driving force calculation unit 33 Target driving force arbitration unit 34 Feedback control unit 41 Detection coil 42 Magnet 43 Pole piece 80 Engine 110 A / D converter 111 Sample value acquisition unit 114 Sample value storage unit 120, 120C Cross Time point calculation unit 121, 121A Crank angle calculation unit 122, 122B Cross time point storage unit 123, 123A, 123B Crank angular velocity calculation unit 124 Crank angular velocity storage unit 130, 130A, 130B Crank angular acceleration calculation unit 14 Maximum arrival time calculation unit 141 maximum arrival time storage unit 142 second cross point calculating unit 160,160B engine torque calculating section

Claims (12)

An acquisition unit that acquires sampling values at a plurality of times of sensor output of a crank angle sensor provided for the crankshaft of the engine;
A reference time point calculation unit that calculates a reference time point that is a time point at which the sensor output becomes a predetermined reference value based on the sampling values at two time points within a section in which the sensor output increases or decreases;
An engine condition parameter calculation device comprising: a parameter calculation unit that calculates a parameter that represents an engine state based on the reference time point calculated by the reference time point calculation unit.   The engine state parameter calculation device according to claim 1, wherein the parameter includes at least one of a crank angle, a crank angular velocity, a crank angular acceleration, and an engine torque.   The reference time point calculation unit calculates a time change rate of the sensor output between the two time points based on the difference between the sampling values at the two time points and the time between the two time points, and the time The engine state parameter calculation device according to claim 1, wherein the reference time point is calculated based on a change rate.   The reference time point calculation unit calculates the time obtained by dividing the difference between the sampling value at one of the two time points and the predetermined reference value by the time change rate, and the one time point and the reference time point. The engine state parameter calculation device according to claim 3, wherein the reference time point is calculated so as to coincide with a time between the time points.   The sampling value at the two time points sandwiches a predetermined value, and the predetermined value is less than the maximum value of the sensor output and larger than the minimum value of the sensor output. The engine condition parameter calculation device described in 1.   The engine condition parameter calculation device according to claim 5, wherein the predetermined value is equal to the predetermined reference value.   The engine condition parameter calculation device according to claim 1, wherein the reference time point calculation unit calculates the reference time point based on the sampling values at three or more points in the section including the two time points.   The reference time point calculation unit derives an approximate curve or approximate line of the sensor output in the section based on the sampling values of the three time points or more, and determines the reference time point based on the approximate curve or approximate line. The engine state parameter calculation apparatus according to claim 7, wherein the calculation is performed.   The reference time point calculated by the reference time point calculation unit is at least one of a first reference time point in an ascending section where the sensor output increases and a second reference time point in a descending section where the sensor output decreases. The engine condition parameter calculation device according to any one of claims 1 to 8, wherein The reference time point calculated by the reference time point calculation unit includes the first reference time point and the second reference time point,
The engine state parameter calculation device according to claim 9, wherein the parameters include a first crank angular speed based on the first reference time point and a second crank angular speed based on the second reference time point. Obtain sampling values at multiple time points of the sensor output of the crank angle sensor provided for the crankshaft of the engine,
Based on the sampling values at two time points in the interval in which the sensor output increases or decreases, a reference time point that is a time point when the sensor output becomes a predetermined reference value is calculated
A computer-implemented engine condition parameter calculation method comprising calculating a parameter representing an engine condition based on the reference time point. Engine,
A crank angle sensor provided for the crankshaft of the engine;
An acquisition unit for acquiring sampling values at a plurality of time points of the sensor output of the crank angle sensor;
A reference time point calculation unit that calculates a reference time point that is a time point at which the sensor output becomes a predetermined reference value based on the sampling values at two time points within a section in which the sensor output increases or decreases;
An engine control system including an engine control unit that controls the engine based on the reference time point calculated by the reference time point calculation unit.

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