JPH0214980B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling operating characteristic quantities of an internal combustion engine operating control means, and in particular to a method for controlling an operating characteristic quantity of an internal combustion engine operation control means, and in particular, a method for controlling the error between the actual opening area of a throttle valve or a control valve that controls the amount of auxiliary air and the detected value of this opening area. The present invention relates to a method of controlling an operating characteristic quantity for accurately controlling the operating characteristic quantity of an operation control means to a required value during low load operation such as idling by always properly correcting it.

Conventionally, operating characteristic quantities of an operation control means for controlling engine operation according to the absolute pressure in the intake pipe and the engine speed, such as the amount of fuel supplied to the engine by a fuel supply amount control device, and the amount of fuel supplied to the engine by a fuel supply amount control device, controlled by an ignition timing control device. The spark ignition timing, the amount of exhaust gas recirculation controlled by the exhaust gas recirculation control device, etc. are determined, and the thus determined operating characteristic quantities are corrected according to the cooling water temperature, intake air temperature, etc., and the required operating characteristic quantities are accurately set. The method is known, for example, from JP-A-58-88436 and JP-A-53-8434. According to this method of determining operating characteristic quantities according to the absolute pressure in the intake pipe and the engine speed (generally referred to as the "speed density method", hereinafter simply referred to as the "SD method"), it is possible to determine the During low-load operation, the degree of change in the absolute pressure in the intake pipe relative to the degree of change in engine speed becomes small, and when pulsations in the absolute pressure in the intake pipe are added to this,
It becomes difficult to accurately detect the absolute pressure inside the intake pipe, and it becomes impossible to accurately set operating characteristic quantities such as fuel amount in accordance with the engine operating conditions, which tends to cause a hunting phenomenon in the engine speed.

In order to solve the above problems, the upstream pressure of the throttle valve is reduced during low load operation such as idling operation.
The pressure ratio between P′ _A and the downstream pressure P _BA (P _BA /P′ _A ) is less than the critical pressure ratio (0.528) that produces sonic flow, and below this critical pressure ratio, the intake air amount is reduced to the downstream pressure of the throttle valve. Does not depend on P _BA or exhaust pressure,
Focusing on the fact that it can depend on the opening area of the throttle valve, the intake air flow rate at low load is detected by detecting only the opening degree of the throttle valve, and based on the detected intake air amount, the fuel flow rate etc. A method for determining the operating characteristic quantity of is proposed in Japanese Patent Publication No. 52-6414.

When such an intake air amount detection method is applied to, for example, fuel injection control, the fuel injection amount needs to be determined as a function of the engine rotational speed in addition to the intake air amount determined as described above. This is because the amount of intake air that passes through the throttle valve per unit time is constant when the opening area of the throttle valve is constant, but the amount of air taken into the engine per intake stroke changes depending on the engine speed. .
Therefore, the basic fuel injection time Ti of the fuel injection valve that injects and supplies fuel to the engine is determined by the following equation.

Ti = (Kθ + K _AI c + ...) × Me ... (1) where Kθ, K _AI c, etc. are opening area coefficients set according to the opening area of the throttle valve, control valve that controls the amount of auxiliary air, etc. , Me is the specified crank rotation angle position of the engine, for example top dead center (TDC)
This is the pulse generation time interval of signal pulses generated every time, and is a value proportional to the reciprocal of the engine rotation speed.

In the method of determining the basic fuel injection time using the above formula (1) (hereinafter simply referred to as the "KMe method"), for example, due to variations in the characteristics of the sensor that detects the valve opening of the throttle valve or sensor installation errors, ,
In addition, due to the adhesion of blow-by gas or carbon contained in the atmosphere to the throttle valve or control valve, an error occurs between the actual opening area value and the detected opening area value of the throttle valve or control valve, and the above-mentioned opening area coefficient Kθ, _KAI
There may be cases where c, etc. are not set to correct values corresponding to the actual aperture area value. Furthermore, even if the actual opening area value of the throttle valve or control valve is detected accurately, if the filter attached to the open end of the intake passage on the atmosphere side becomes clogged, the actual intake air amount may differ from the detected intake air amount. The air-fuel ratio becomes richer. In order to avoid these inconveniences, a correction value or correction is set according to the voltage value from a variable power supply for adjusting the air-fuel ratio that is provided outside the fuel injection control device at the time of factory shipment or during maintenance. The coefficient is the basic fuel injection time Ti determined by the above equation (1).
A method of correcting by multiplying or adding is considered, but this method requires manual adjustment and also requires an input circuit including the above-mentioned variable power supply for adjusting the air-fuel ratio, A/D converter, etc. This is not desirable as it becomes necessary and causes an increase in the price of the product.

The present invention has been made in order to solve such problems, and it controls the operation of an internal combustion engine that includes an intake passage and an intake air amount control means that controls the amount of intake air by adjusting the opening area of the passage. In a method for controlling an operating characteristic quantity of an operation control means to a required value according to an operating state of an engine every time a pulse of a predetermined control signal is generated, it is determined whether or not the engine is in a predetermined low-load operating state. When the engine is in the predetermined low-load operating state, the opening area of the intake passage adjusted by the intake air amount control means is detected, and a first operating characteristic quantity control value is determined according to the detected opening area value. At the same time, the intake air pressure and engine rotational speed downstream of the intake air amount control means in the intake passage are detected, and a second operating characteristic quantity is determined according to the detected intake air pressure value and engine rotational speed value. determining a control value, determining an operating characteristic quantity correction value for each pulse generation of the predetermined control signal from the thus determined first and second operating characteristic quantity control values, and obtaining an average value of the thus determined correction values; The first operation characteristic quantity control value determined at the time of the current pulse generation of the predetermined control signal is corrected by the average value of the determined correction values, and the operation characteristic quantity of the operation control means is adjusted to the first operation so corrected. By controlling the characteristic quantity control value, detection errors in the actual opening area of throttle valves and control valves are always properly corrected without relying on artificial methods, and the operating characteristic quantity of the operation control means is controlled at low loads such as idling. An object of the present invention is to provide a method for controlling an operating characteristic quantity of an operation control means for an internal combustion engine, which allows accurate setting of a required value suitable for the operating state.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing the entirety of a fuel injection control device for an internal combustion engine including a plurality of auxiliary air amount control valves for controlling auxiliary air amount, to which the method of the present invention is applied; For example, a four-cylinder internal combustion engine is shown, and an engine 1 is connected to an intake pipe 3 and an exhaust pipe 4, both of which have an air cleaner 2 attached to their open ends. A throttle valve 5 is arranged in the middle of the intake pipe 3, and the intake pipe 3 downstream of the throttle valve 5
A first air passage 8 and a second air passage 8 open to the atmosphere and communicating with the atmosphere.
An air passage 8' is provided. First air passage 8
An air cleaner 7 is attached to the open end on the atmosphere side, and a first auxiliary air amount control valve (hereinafter simply referred to as "first control valve") 6 is disposed in the middle of the first air passage 8. The first control valve 6 is a normally closed solenoid valve, and is composed of a solenoid 6a and a valve 6b that opens the first air passage 8 when the solenoid 6a is energized. ) 9).

The second air passage 8' branches into a third air passage 8'' in the middle of the passage, and air cleaners 7', 7'' are provided at the open ends of the second air passage 8' and the third air passage 8'' on the atmosphere side, respectively. A control valve similar to the first control valve is installed between the branch point of the third air passage 8'' of the second air passage 8' and the atmospheric opening end side, and in the middle of the third air passage 8''. A second control valve 6' and a third control valve 6'', which are normally closed solenoid valves, are provided. Each control valve 6', 6'' has a solenoid 6'a,
6''a and valves 6'b, 6''b that open each passage when the solenoid is energized, and one end side of each solenoid 6'a and 6''a of each control valve 6', 6'' is grounded, and the other ends are connected to switches 18 and 19, respectively.
It is connected to the DC power supply 20 via the ECU 9 as well as to the ECU 9.

A branch passage 8b that branches downstream of the first control valve 6 is connected to the first air passage 8, and an air cleaner 11 is connected to the open end of the branch passage 8b on the atmosphere side.
is attached, and a fast idling control device 10 is disposed in the middle of the branch passage 8b. The fast idling control device 10 includes:
For example, a valve body 10a that can be pressed against a valve seat 10b by a spring 10c to close the branch passage 8b.
, a detection device 10d that expands and contracts the arm 10d' in response to the engine cooling water temperature, and a lever 10e that rotates in response to the expansion and contraction of the arm 10d' of the detection device and displaces the valve body 10a in the opening and closing direction. has been done.

Absolute pressure in the intake pipe communicates with the intake pipe 3 via a fuel injection valve 12 and a pipe 15 between the engine 1 of the intake pipe 3 and the opening 8a of the first air passage and the opening 8'a of the second air passage. A sensor 16 is attached to each. The fuel injection valve 12 is connected to a fuel pump (not shown) and electrically connected to the ECU 9, and the absolute pressure sensor 16 is also connected to the ECU 9.
Electrically connected to ECU9. Furthermore, the throttle valve 5 is provided with a throttle valve opening sensor 17.
However, the engine 11 body has an engine water temperature sensor 1.
3 is provided, and this sensor 13 is made of a thermistor or the like, and is inserted into the circumferential wall of the engine cylinder filled with cooling water, and supplies the detected water temperature signal to the ECU 9.

An engine rotation speed sensor (hereinafter referred to as "Ne sensor") 14 is attached around the camshaft or crankshaft (not shown) of the engine, and the Ne sensor 14 receives a TDC signal, that is, a predetermined value every 180° rotation of the engine crankshaft. It outputs one pulse at the crank angle position of ECU9.
sent to.

Reference numeral 21 indicates an electrical device such as a headlight, a brake light, a radiator cooling fan, etc., and the electrical device 21 is connected to the ECU via a switch 22.
It is electrically connected to 9. Reference numeral 23 indicates an atmospheric pressure sensor, and an atmospheric pressure signal detected by the atmospheric pressure sensor 23 is supplied to the ECU 9.

Next, the operation of the fuel injection control device configured as described above will be explained.

First, the switch 18 operates in conjunction with, for example, an air conditioner switch (not shown) that operates an air conditioner (not shown), and when the switch 18 is closed, it supplies an air conditioner on signal indicating the operation of the air conditioner to the ECU 9 and also turns on the second control valve 6 . ' solenoid 6'a
is energized to open the valve 6'b and supply a predetermined amount of auxiliary air to the engine 1 corresponding to the increase in engine load due to the operation of the air conditioner during idling. For example, in the case of an internal combustion engine equipped with an automatic transmission, the switch 19 is attached to a shift lever (not shown), and when the shift lever is operated to the engagement position of the automatic transmission, the switch 19 closes and engages the automatic transmission. An on signal (hereinafter referred to as the "D range signal") indicating the automatic transmission is supplied to the ECU 9, and the solenoid 6"a of the third control valve 6" is energized to open the valve 6"b, thereby controlling the automatic transmission during idling. A predetermined amount of auxiliary air is supplied to the engine 1 in response to an increase in engine load due to operation.

As mentioned above, second and third control valves are provided separately for mechanical loads such as air conditioners and automatic transmissions that are relatively large loads on the engine, such as auxiliary mechanical devices that are directly driven by the engine. The idle speed is kept constant according to each load.

The fast idling control device 10 controls the engine cooling water temperature to a predetermined value (for example, 50°C) during a cold start.
℃). More specifically,
The detection device 10d of the fast idling control device 10 expands and contracts the arm 10d' in response to the engine coolant temperature. Various devices can be used as the detection device 10d, for example, it may be filled with wax and utilize its thermal expansion characteristics. If the engine cooling water temperature is lower than a predetermined value, the detection device 10d
The arm 10d' is in a contracted state, and the lever 10e is rotated by the spring 10f, displacing the valve body 10a to the right against the spring 10c to open the branch passage 8b. When this branch passage 8b is open, sufficient auxiliary air is supplied to the engine 1 via the filter 11 and the passages 8b and 8, so the engine rotation speed can be maintained at a rotation speed higher than the normal idle rotation speed, so it is cold. Normal operation is ensured without fear of engine stall during idling operation.

When the arm 10d' of the detection device 10d expands due to thermal expansion as the engine cooling water temperature rises due to warm-up, the arm 10d' pushes the lever 10e upward and rotates it clockwise in the figure. At this time, the valve body 10e gradually moves to the left due to the pressing force of the spring 10c, and when the engine cooling water temperature reaches a predetermined value or more, the valve body 10a comes into contact with the valve seat 10b and closes the branch passage 8b. The supply of auxiliary air via the fast idling control device 10 is then stopped.

On the other hand, the engine 1 of electrical equipment 21 such as headlights, brake lights, and radiator cooling fans
The first control valve 6 is used to control the supply amount of the auxiliary air amount to respond to the electrical load, which is a relatively small load, and to increase or decrease the auxiliary air amount with high accuracy so that the engine speed becomes the target idle speed. used. That is, the ECU 9 detects the throttle valve opening sensor 17 for each top dead center (TDC) signal of the engine.
The first control valve 6 is controlled based on the values of engine operating parameter signals supplied from the absolute pressure sensor 16 , cooling water temperature sensor 13 , engine speed sensor 14 , and atmospheric pressure sensor 23 and the electrical load status signal from the electrical device 21 . In addition to determining the operating condition in which auxiliary air should be supplied by auxiliary air volume to minimize the difference,
Therefore, the valve opening duty ratio Dou _T of the first control valve 6 is calculated, and a drive signal for operating the first control valve 6 is supplied to the first control valve 6 according to the calculated value.

The solenoid 6a of the first control valve 6 is energized for a valve opening time corresponding to the valve opening duty ratio Dou _T , and the valve 6b is opened to open the first air passage 8, and the solenoid 6a is energized for a valve opening time corresponding to the valve opening duty ratio Dou T. A fixed amount of air is supplied to the engine 1 via the first air passage 8 and the intake pipe 3.

On the other hand, the ECU 9 calculates the fuel injection time Tou _T of the fuel injection valve 12 based on the various engine operating parameter signal values described above and in synchronization with the TDC signal using the formula shown below.

Tou _T = Ti × K ₁ + K ₂ ... (2) Here, Ti indicates the basic injection time, and the basic injection time Ti is the period when the engine is in a range where predetermined idle operating conditions are satisfied, as will be described in detail later. It is set by either the SD method or the KMe method depending on whether it exists or not.

The correction coefficients or correction values K ₁ and K ₂ are correction coefficients or corrections calculated according to engine operating parameter signals from engine operating parameter sensors such as the various sensors mentioned above, such as the throttle valve opening sensor 17 and the intake air temperature sensor 11. value and correction coefficient
For example, K ₁ is given by the following equation.

K ₁ = K _TA × Kp _A × K _TW × K _WOT ×…… (3) Here, K _TA is the intake air temperature correction coefficient, Kp _A is the atmospheric pressure correction coefficient, and these correction coefficients K _TA , Kp As will be described later, _A is set to a value appropriate for each method using separate calculation formulas for the SD method and the KMe method.

Further, K _TW is a fuel increase coefficient set according to the engine water temperature T _W detected by the coolant temperature sensor 13, and K _WOT is a constant and is a enrichment coefficient when the throttle valve is fully open.

The ECU 9 supplies the fuel injection valve 12 with a drive signal to open the fuel injection valve 12 based on the fuel injection time Tou _T determined as described above.

Figure 2 is a diagram showing the circuit configuration inside the ECU 9 in Figure 1, and shows the engine rotation speed Ne sensor 14 in Figure 1.
The output signal is waveform-shaped by a waveform shaping circuit 901 and then supplied to a central processing unit (hereinafter referred to as "CPU") 903 as a TDC signal.
It is also supplied to the Me counter 902. The Me counter 902 counts the time interval from the input of the previous TDC signal from the engine rotation speed Ne sensor 14 to the input of the current TDC signal.
Me is proportional to the reciprocal of the engine speed Ne. Me
Counter 902 supplies this count value Me to CPU 903 via data bus 910.

After the respective output signals from the throttle valve opening sensor 17, intake pipe absolute pressure P _BA sensor 16, cooling water temperature sensor 13, and atmospheric pressure sensor 23 shown in FIG. The signals are sequentially supplied to an A/D converter 906 by a multiplexer 905. A/D converter 9
06 sequentially converts the output signals from each of the sensors described above into digital signals and supplies the digital signals to the CPU 903 via the data bus 910.

The switch 18 that opens the second control valve 6' when the air conditioner is activated, the switch 19 that opens the third control valve 6'' when the automatic transmission is engaged, and the switch 22 of the electric device 21 shown in FIG. - Each off signal is corrected to a predetermined voltage level by a level correction circuit 912, and then converted into a predetermined signal by a data input circuit 913 and sent to the CPU 900 via a data bus 910.
supplied to

The CPU 903 further uses a read-only memory (hereinafter referred to as "ROM") via a data bus 910.
907, random access memory (hereinafter referred to as "RAM") 908, nonvolatile memory 91
4 and drive circuits 909 and 911, RAM 908 temporarily stores calculation results etc. by CPU 903, and ROM 907 stores control programs etc. executed by CPU 903. The non-volatile memory 914 is composed of, for example, CMOS,
It stores the air-fuel ratio correction coefficient value K _IDL that is applied when calculating the basic fuel injection time Ti using the KMe method, which will be described later, and this stored value is retained even if the ignition switch (not shown) is turned off. Ru.

The CPU 903 determines the engine operating state according to the aforementioned various engine parameter signals and the on/off states of the switches 18, 19, and 22 according to the control program stored in the ROM 907, and opens the aforementioned first control valve 6. In addition to calculating the valve duty ratio Dou _T , the valve opening time Tou _T of the fuel injection valve 12 is calculated as will be described in detail later, and a control signal corresponding to these calculated values is sent to the drive circuits 911 and 909 via the data bus 910. supply each. The drive circuits 911 and 909 supply drive signals for opening the first control valve 6 and the fuel injection valve 12 to the control valve 6 and the fuel injection valve 12, respectively, while the above-mentioned control signal is being supplied.

Figure 3 is executed by the CPU 903 in Figure 2.
It is a flowchart showing a method of calculating the valve opening time Tou _T of the fuel injection valve 12. Steps 1 to 3 in FIG. 3 are for determining whether or not the engine has met a predetermined idle operating condition. First, in step 1, the engine rotation speed Ne has reached the predetermined rotation speed.
It is determined whether or not the engine speed is below N _IDL (for example, 1000 rpm), and if the determination result is negative (No), the idle operation condition is not satisfied and the process immediately proceeds to step 4, which will be described later. The determination result of step 1 is positive (Yes)
If so, proceed to step 2 and check the absolute air P _BA in the intake pipe.
It is determined whether or not the engine load is lower than the reference pressure P _BA c, that is, below the reference pressure P _BA c. This reference pressure P _BA c is the ratio of the absolute pressure P _BA in the intake pipe on the downstream side of the throttle valve 5 to the absolute pressure P in the intake pipe on the upstream side of the throttle _valve 5 (P _BA /P' _A ), which passes through the throttle valve 5. The reference pressure P _BA c, which is set to determine whether or not the intake flow velocity becomes equal to or lower than the critical pressure ratio (0.528) at which the air flow becomes sonic, is given by the following equation.

P _BA c=P′ _A × (critical pressure ratio)=P′ _A × Here, χ is the specific heat ratio of air (χ = 1.4),
Since the absolute pressure P _A ' in the intake pipe upstream of the throttle valve 5 is approximately equal to the atmospheric pressure P _A detected by the atmospheric pressure sensor 23 in FIG. The relationship between pressure P _BA c and atmospheric pressure P _A is the fourth
As shown in the figure.

If the determination result in step 2 is negative (No),
It is determined that the predetermined idle operating condition is not met and the process proceeds to step 4, and if affirmative (Yes), the process proceeds to step 3. In step 3, the valve opening degree θ _TH of the throttle valve 5
It is determined whether or not the opening degree θ _IDLH is less than or equal to the predetermined opening degree θ IDLH. The reason for this determination is that when the throttle valve 5 shifts from an idling operating state in which the throttle valve 5 is in a substantially fully closed position to an accelerating operating state in which the throttle valve is rapidly opened, the engine speed and intake pipe absolute If the acceleration operation state is determined based only on pressure changes, the detection of the acceleration operation state will be delayed due to the response delay of the absolute pressure sensor, etc. Therefore, the acceleration operation state is detected by the throttle valve opening, and when the acceleration operation state is detected, the acceleration operation state is detected by the throttle valve opening. This is because it is necessary to calculate an appropriate amount of acceleration fuel using the SD method, which will be described later, and provide this fuel amount to the engine. If the determination result in step 3 is negative (No), it is assumed that the predetermined idle operation condition is not satisfied, and the process proceeds to step 4, where it is affirmative (Yes).
If so, proceed to step 6.

In step 4, which is executed when the idle operating conditions are not satisfied, the basic fuel injection time Ti is determined by the SD method. In other words, the _ECU
The basic fuel injection time Ti stored in the ROM 907 in ROM 907 is read out. Based on the basic injection time Ti thus determined, the fuel injection time Tou _T is calculated based on the equation (2) (step 5).

In step 6, which is executed when the idle operating conditions are met, the basic injection time Ti is determined by the KMe method, as will be described in detail later, and the fuel injection time Tou _T is calculated from this basic injection time Ti (step 5). .

In the determination of steps 1 to 3 above, the determination value at each step is set to a different value when the engine enters and exits the operating range where the predetermined idle operating conditions are satisfied, and the KMe
The selection of the method and SD method may have hysteresis characteristics to stabilize engine operation control.

FIG. 5 is a flowchart showing the procedure for determining the basic injection time Ti value using the KMe method executed in step 6 of FIG.

Step 1 in Fig. 5 is to obtain the opening area coefficient value Kθ of the throttle valve 5. The Kθ value is obtained from the graph showing the relationship between the throttle valve opening θ _TH and the opening area coefficient Kθ shown in Fig. 6. . More specifically, for example, predetermined values Kθ 1 to Kθ 5 are stored in advance in the ROM 907 in the ECU 9 as Kθ values corresponding to the throttle valve openings θc ₁ to θc ₅ , and predetermined values Kθ ₁ to Kθ ₅ are stored adjacent to the actual throttle valve opening value θ _TH . Save the two Kθ values to ROM90
The opening area coefficient value Kθ corresponding to the actual throttle valve opening value _θTH is determined by reading out from 7 and performing interpolation calculation.

Next, in step 2, the opening area coefficient value K _AI c of the first control valve 6 is determined. The opening area of the first control valve 6, and hence the K _AI c value, can be determined as a function of the valve opening duty ratio Dou _T , and FIG. 7 shows the opening duty ratio Dou _T of the first control valve 6 and the opening area coefficient K. _A.I.c.
This is a graph showing a table of the relationship between the opening area coefficient KAI c and the valve opening duty ratio of the first control valve 6, that is, the opening area coefficient value K _AI c corresponding to the opening area, using the same method as the opening area coefficient Kθ of the throttle valve. Desired.

In step 3, the aperture area coefficient value K _FI of the fast idling control device 10 is determined. 1st
The passage opening area of the fast idling control device 10 shown in the figure, and hence the K _FI value, can be determined as a function of the cooling water temperature T _W , and FIG. 8 shows the function of the engine cooling water temperature T _W and the opening area coefficient K _FI . The opening area coefficient value K _FI of the fast idling control device 10 is determined by the same method as the opening area coefficient Kθ of the throttle valve described above.

In step 4, the opening area coefficient value K _A c of the second control valve 6' is determined. The second control valve 6' is fully open or fully closed depending on the on/off state of the switch 18, which is linked to the air conditioner switch.
8 is in the on state, a predetermined value K _A c corresponding to the aperture area when fully opened is read from the ROM 907 .

Step 5 is executed when the method of the present invention is applied to an internal combustion engine equipped with an automatic transmission, and step 19 indicates engagement of the automatic transmission.
The third control valve 6'' is fully opened by the ON signal of
The predetermined value K _AT corresponding to the opening area when fully opened is
Read from ROM907.

Next, in steps 6 and 7, the CPU 903 calculates correction coefficient values ΔK _IDL and K _IDL according to the present invention. These correction coefficient values are obtained by calculation formulas derived as follows.

Assuming that there is no pulsation in the intake pipe absolute pressure P _BA and that an accurate value can be detected, the opening time Tou _T1 of the fuel injection valve 12 can be determined by the SD method by considering only atmospheric pressure correction and intake air temperature correction. Then, it can be obtained using the following formula.

Tou _T1 = Ti _MA p × Kp _A1 × K _TA1 ...(5) Here, Ti _MA p is the basic injection time, and the intake pipe absolute pressure P detected by the intake pipe absolute pressure sensor 16 in Fig. 1 is _BA and the engine speed Ne detected by the Ne sensor 14 as shown in FIG.
It is read from the basic injection time Ti map stored in the ROM 907. The correction coefficient Kp _A1 is an atmospheric pressure correction coefficient applied to the SD method.
As disclosed in No. 58-58337, it is determined by the following formula.

Kp _A1 =1-(1/ε)(P _A /P _BA ) ^1/ 〓/1-(1/
ε) (P _AO /P _BA ) ^1/ 〓……(6) Here, P _A is the actual atmospheric pressure (absolute pressure), P _A0 is the standard atmospheric pressure, ε is the compression ratio, and χ is the specific heat ratio of air. . Atmospheric pressure correction coefficient Pp _A1 is the amount of air taken into the engine cylinder during one intake stroke, which is the absolute pressure in the intake pipe P _BA
and the absolute pressure in the exhaust pipe, which can be considered to be approximately equal to atmospheric pressure P _A. In order to keep the air-fuel ratio constant, the actual atmospheric pressure P _A for the intake air amount at standard atmospheric pressure P _AO . Since it is sufficient to increase or decrease the fuel amount at the same ratio as the ratio of the intake air amount in

Furthermore, from equation (6), when P _A <P _AO , Kp _A1 >1. That is, when the atmospheric pressure P _A is lower than the standard atmospheric pressure P _AO at high altitudes, etc., the amount of intake air increases under the same intake pipe absolute pressure P _BA as at flatlands. Therefore, if the fuel amount, which is set as a function of the intake pipe absolute pressure P _BA and the engine speed, is applied at low atmospheric pressure such as at high altitudes, the mixture will become lean, and the increase coefficient Kp _A1 will cause the mixture to become leaner. Leanness is prevented.

The correction coefficient _KTA1 is an intake temperature correction coefficient applied to the SD method, and is determined by the following equation, as shown in, for example, Japanese Patent Application Laid-Open No. 88436/1983.

K _TA1 = 1/1 + C _TAMA p (T _A - T _A0 ) ...(7) Here, _TA is the temperature of the intake air flowing in the intake pipe (℃), and T _AO is the calibration variable. For example,
Set at 50℃. C _TAMA p is a calibration coefficient that is a constant value (for example,
1.26×10 ^-3 ). C _TAMA p(T _A
-T _AO ) is a smaller value than 1, so it can be approximately determined by K _TA1 = 1-C _TAMA p(TA _- T _AO ) (8).

On the other hand, the valve opening time determined by the KMe method
Tou _T2 can be obtained from the following equation by considering only the atmospheric pressure correction and intake temperature correction as described above.

Tou _T2 = (Kθ + K _AI c + K _FI + K _A c + K _AT )・Me・K _PA2・K _TA2 ...(9) Here, Kθ, K _AI c, etc. are shown in step 1 of Figure 5 above.
to 5 are the opening area coefficients obtained, and Me is supplied from the Me counter 902 in FIG.
This is the TDC signal pulse generation time interval. Kp _A2 and
K _TA2 is an atmospheric pressure correction coefficient and an intake temperature correction coefficient applied to the KMe method, and these coefficients are obtained as follows.

The ratio of the downstream pressure P _BA to the intake pipe internal pressure P _A ′ upstream of the throttle part of the intake pipe such as a throttle valve (P _BA /P _A ′)
is below the critical pressure ratio (0.528), the air passing through the throttle becomes a sonic flow, and the amount of intake air
Ga (g/sec) is Here, A is the equivalent opening area (mm ² ) of the throttle part such as a throttle valve, C is the correction coefficient determined by the shape of the throttle part, etc.
P _A is the atmospheric pressure (P _A = P _A ′, mmHg), x is the specific heat ratio of air, R is the gas constant of air, T _AF is the intake air temperature just before the throttle (℃), and g is the gravitational acceleration (m/ sec ² ). The ratio between the intake air amount Gao at standard atmospheric pressure P _AO and the intake air amount Ga at arbitrary atmospheric pressure P _A is:
When the intake air temperature T _AF and opening area A are constant, it is given by Ga/Gao = P _A /P _AO , and if the amount of fuel supplied to the engine is changed at the same ratio as this intake air amount ratio, the air-fuel ratio can be kept constant. Therefore the fuel flow rate
Gf is given by Gf=GfoP _A /760 from the fuel flow rate Gfo at standard atmospheric pressure P _AO (=760 mmHg). Atmospheric pressure correction factor here
Kp _A2 can be theoretically expressed as Kp _A2 = P _A /760. However, in practice, the above equation can be expressed as Kp _A2 = 1 + Cp _A P _A -760/760 (11), taking into account various errors caused by the shape of the intake passage. Here, Cp _A is a chilibration variable set experimentally.

Furthermore, from the above equation (11), when P _A <760 mmHg, Kp _A <1. In other words, in the KMe method, the amount of intake air is determined only by the equivalent opening area A of the intake passage restrictor such as the throttle _valve , based on the standard atmospheric pressure _PAO .
When the pressure drops below P _AO (=760mmHg), the amount of intake air decreases in proportion to the atmospheric pressure P _A , and if the fuel amount is set according to the opening area A described above,
Contrary to the SD method, the mixture becomes richer. The correction coefficient Kp _A2 mentioned above is for preventing such enrichment.

Next, in the above equation (10), if the atmospheric pressure P _A and the opening area A are constant, the temperature upstream of the throttle part is the reference temperature.
Intake air amount Gao and arbitrary temperature T _AF when T _AFO
The ratio with the intake air amount Ga is The air-fuel ratio can be kept constant by changing the amount of fuel supplied to the engine at the same ratio as this intake air amount ratio. Therefore the fuel flow rate
Gf is the flow rate Gfo at reference temperature T _AFO given by. Intake air temperature correction coefficient K _TA2 Then, K _TA2 can be approximately expressed by the following equation by transforming the above equation.

K _TA2 ≒1-T _AF -T _AFO /2 (T _AF +273) ≒1-α (T _AF -T _AFO ) ...(12) K _TA2 obtained by equation (12) is the intake air temperature upstream of the throttle part
K is given as a function of _AF . However, it has been experimentally confirmed that the relationship between the throttle upstream temperature T _AF and the downstream temperature T _A is approximately given by the following equation under idling operating conditions.

T _AF =aT _A +b (13) where a and b are constants.

Formula (13) considering that T _AFO = aT _AO + b
Substituting and rearranging into equation (12), the equation can be expressed as K _TA2 = 1-aα( _TA - _TAO ) = 1-C _TA c(TA _{- TAO} )...(14) I can do it.

As mentioned above, the opening time Tou _T1 and the valve opening time of the fuel injection valve 12 are corrected and determined by the atmospheric pressure and intake temperature correction coefficients suitable for the SD method and the KMe method, respectively.
Tou _T2 should essentially be the same value if there is no pulsation in the intake pipe absolute pressure P _BA . However, in reality, since there is pulsation in the intake pipe absolute pressure P _BA, the valve opening time Tou _T1 obtained by the SD method of equation (5) includes a pulsation component of the absolute pressure P _BA , and the equation ( The valve opening time Tou _T2 determined by the KMe method in 9) includes the installation error of the throttle valve opening sensor 17, the air cleaners 2, 7, 7',
The valve opening times Tou _T1 and Tou _T2 generally take different values due to the inclusion of error components due to clogging _, etc. of the throttle valve. If we correct the valve opening time obtained by equation (9) using the correction coefficient ΔK _IDL , which takes into account the error components caused by the installation error of the opening sensor, and let this be Tou _T2 ′, then the valve opening time is
Tou _T2 ′ is Tou _T2 ′=(Kθ+K _AI c+K _FI +K _A c +K _AT +ΔK _IDL )・Me・Kp _A2・K _TA2
...(15) becomes. Here, since the valve opening times Tou _T1 and Tou _T2 ' determined by equations (5) and (15) are equal, ΔK _IDL can be determined from the following equation.

ΔK _IDL = Ti _MAP ×K _PA1 ×K _TA1 /Me × K _PA2 ×K _TA2 − (Kθ+K _AI c+K _FI +K _A c+K _AT )
...(16) Substitute the ΔK _IDL value obtained for each TDC signal pulse generation using equation (16) into the following equation, and obtain the correction coefficient value K _IDL as the average value.

_{K IDL = _ _ _} Read from memory 914. X _IDL is a constant set according to the pulsation period of the intake pipe absolute pressure P _BA , and an appropriate value between 1 and 256 is selected.

The correction coefficient value K _IDL obtained by Equation (17) is determined by the error component of the throttle valve opening sensor because the error component due to the pulsation of the intake pipe absolute pressure P _BA included in the ΔK _IDL value is canceled out by the averaging process. This value represents only error components such as installation errors and air cleaner clogging. Since this correction coefficient value K _IDL is calculated every time a pulse of the TDC signal is generated, it represents the latest correction coefficient value corresponding to the passage of time for error causes such as clogging of the air cleaner and carbon estimation.

The CPU 903 calculates a correction value ΔK IDL based on the above equation (16) in step 6, and calculates the correction value ΔK _IDL based on the correction value ΔK _IDL and the correction coefficient value K _IDL ' read out from the nonvolatile memory 914 in step 7. A correction coefficient value K _IDL is calculated based on equation (17), and stored in the nonvolatile memory 914 as a new correction coefficient value K _IDL ', and the process proceeds to step 8. In step 8, the basic fuel injection time is determined based on the following calculation formula (18) using the opening area coefficients determined in steps 1 to 5, the correction coefficient calculated in step 7, and the Me value from the Me counter 902.
Determine Ti.

Ti=(Kθ+K _AI c+K _FI +K _A c +K _AT +K _IDL )・Me...(18) Note that the method for obtaining the average value of the correction value ΔK _IDL is limited to that obtained based on the above equation (17). Of course, the arithmetic mean value of a predetermined plurality of correction values ΔK _IDL obtained before the current pulse generation of the TDC signal may be used.

Further, in the above-described embodiments, the case where the method of the present invention is applied to control the amount of fuel supplied to the engine by the fuel supply control device of an internal combustion engine has been described, but the present invention is not limited to this embodiment.
The method of the present invention can be applied as long as the operating characteristic quantity of the operation control means that controls the operation of the internal combustion engine is determined by the parameter representing the intake air amount. The method of the present invention can also be applied to control of operating characteristic quantities of flow rate control devices and the like.

As described in detail above, according to the method for controlling the operating characteristic quantity of the operation control means for an internal combustion engine of the present invention, when the engine is in a predetermined low load operating state, the opening of the intake passage is adjusted by the intake air amount control means. detecting the area, determining a first operating characteristic quantity control value according to the detected opening area value, and detecting the intake air pressure and engine rotation speed downstream of the intake air amount control means in the intake passage; A second operating characteristic quantity control value is determined according to the detected intake air pressure value and engine rotational value, and the first and second
An operating characteristic quantity correction value is obtained from the operating characteristic quantity control value every time a pulse of the predetermined control signal is generated, an average value of the correction values thus obtained is obtained, and the first Since the operating characteristic quantity control value is corrected by the average value of the correction values obtained above, and the operating characteristic quantity of the operation control means is controlled to the thus corrected first operating characteristic quantity control value, it is not necessary to rely on an artificial method. Detection errors in the actual opening area of throttle valves and control valves can be corrected properly and automatically at all times, without causing problems, and the operating characteristic quantities of the operation control means can be accurately adjusted to the required values suitable for low-load operating conditions such as idling. setting, it is possible to improve the exhaust gas characteristics, fuel efficiency characteristics, etc. of the engine.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection control device for an internal combustion engine to which the method of the present invention is applied, FIG. 2 is a circuit diagram showing the internal configuration of the electronic control unit (ECU) in FIG. 1, and FIG. A flowchart showing a method of calculating the opening time Tou _T of a fuel injection valve,
Figure 4 shows the reference pressure P _BA c and atmospheric pressure P _A that are set to determine whether the absolute pressure in the intake passage is such that the intake air passing through the throttle valve becomes a sonic flow.
FIG. 5 is a graph showing the relationship between
A flowchart showing the procedure for determining Ti, FIG. 6 is a graph showing a table of the relationship between the opening area coefficient Kθ of the throttle valve and the throttle valve opening θ _TH , and FIG. Opening area coefficient K _AI
Figure 8 is a graph showing the relationship between c and the valve opening duty ratio Dou _T of the same control valve. Figure 8 is the opening area coefficient K _FI of the fast idling control device in Figure 1
2 is a graph showing a table of the relationship between T and engine cooling water temperature T _W . 1...Internal combustion engine, 3...Intake passage, 5...
Throttle valve, (throttle valve), 6...first control valve,
6'...Second control valve, 6''...Third control valve, 8,
8', 8''...first, second and third intake passages, 9...
...Electronic control unit (ECU), 10...
Fast idling control device, 12...Fuel injection valve, 14...Engine speed sensor, 16...
...Intake pipe absolute pressure sensor, 17...Throttle valve opening sensor, 23...Atmospheric pressure sensor, 903...
CPU, 907...ROM, 914...Non-volatile memory.

Claims (1)

[Scope of Claims] 1. The operating characteristic quantity of the operation control means for controlling the operation of an internal combustion engine including an intake passage and an intake air amount control means for controlling the amount of intake air by adjusting the opening area of the passage. In a method for controlling an operating characteristic quantity to a required value according to an operating state, it is determined whether the engine is in a predetermined low load operating state, and when the engine is in the predetermined low load operating state, the intake air amount is controlled to a required value according to the operating state of the engine. detecting an opening area of the intake passage adjusted by a control means, determining a first operating characteristic quantity control value according to the detected opening area value; detecting an engine parameter representing the engine load; A second operating characteristic quantity control value is determined in accordance with the detected engine parameter, an operating characteristic quantity correction value is determined from the thus determined first and second operating characteristic quantity control values, and the operating characteristic quantity correction value is determined based on the first operating characteristic quantity control value. Operation of an internal combustion engine operation control means, characterized in that the quantity control value is corrected by the determined correction value, and the operation characteristic quantity of the operation control means is controlled to the thus corrected first operation characteristic quantity control value. Characteristic quantity control method. 2. The internal combustion engine according to claim 1, wherein the operation control means is a fuel supply amount control means, and the operating characteristic quantity is the amount of fuel supplied to the engine by the fuel supply amount control means. A method for controlling an operating characteristic quantity of an operating control means.