JPH0894462A - Torque fluctuation measuring device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] To measure the torque fluctuation for each cylinder of an internal combustion engine having multiple cylinders. [Structure] A pair of magnetic films 14 are provided in the plane of a flywheel (drive plate) 12 so as to face each other by 180 °, and a pair of magnetostrictive torque sensors 16 are arranged at a rear portion of an engine block. The output from the magnetostrictive torque sensor 16 is input to the A / D converter 20 and the integrator 22 via the analog signal processing circuit 18. A / D converter 20 and integrator 22
Then, based on the angle signals from the rotary encoder 24, the waveform shaping circuit 26, and the frequency divider 28, the torque signal in the vicinity of the torque peak of each cylinder is digitally processed and integrated. The obtained integrated torque value for each cylinder is supplied to the variance calculators 32 to 38 for each cylinder via the data memory 30, and the variance as torque fluctuation is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque fluctuation measuring device for an internal combustion engine, and more particularly to a device for measuring torque fluctuation of each cylinder.

[0002]

2. Description of the Related Art Conventionally, a lean burn engine having a large air-fuel ratio (Air / Fuel) has been developed in order to reduce fuel consumption. However, as shown in FIG. 10, when the A / F increases, combustion becomes unstable due to misfire or the like, and torque fluctuation increases, and this torque fluctuation greatly affects the comfort of the vehicle. From the viewpoint, it is important to accurately evaluate the torque fluctuation in the lean burn state.

As a method of measuring torque, for example, the torque measuring device disclosed in Japanese Patent Laid-Open No. 62-55533 can be used. This torque measuring device detects the amount of magnetostriction of a rotating magnetic body that transmits torque by using a magnetic sensor, and measures the transmitted torque in a non-contact manner based on the amount of magnetostriction detected by the magnetic sensor. Normally, the magnetic sensor is mounted between the propeller shaft and the dynamometer, and the output from the magnetic sensor passes through the bandpass filter, and then the average value of the extracted fluctuation signal within a predetermined time is calculated to calculate the torque fluctuation. It is output as a value.

On the other hand, instead of directly measuring the torque as described above, the rotation speed is calculated from the rotation pulse signal that can be taken out from the engine as a standard signal, and the torque is proportional to the change in the rotation speed. Methods for estimating fluctuations are also known. However, this method has a drawback that the instantaneous torque cannot be detected accurately and the engine combustion behavior cannot be accurately grasped.

[0005]

On the other hand, in a multi-cylinder engine, the lean limit is different for each cylinder due to variations among the cylinders (fuel, air amount, compression ratio, etc.), so torque fluctuations are detected for each cylinder. The need arises. However, the above-mentioned conventional technique has a problem that only the average torque fluctuation can be detected as described above, and the torque fluctuation between the combustion cycles of each cylinder cannot be detected. Therefore, even when controlling the fuel injection amount based on the detected lean limit, there is no choice but to perform control with a margin in the engine potential in consideration of variations between cylinders, and sufficient fuel efficiency is obtained. There were also problems that I could not get.

The present invention has been made in view of the above problems of the prior art, and the object thereof is to accurately measure the torque fluctuation of each cylinder in a multi-cylinder engine, and further based on the measured torque fluctuation. An object of the present invention is to provide a torque fluctuation measuring device for an internal combustion engine, which is capable of preventing misfire in each cylinder and further reducing fuel consumption.

[0007]

In order to achieve the above object, a torque fluctuation measuring device for an internal combustion engine according to claim 1,
A magnetic film attached to the surface of a flywheel connected to the crankshafts of a plurality of cylinders, a magnetostrictive torque detection means provided at a position facing the magnetic film at the rear of the engine block, and synchronized with the rotation of the crankshaft. And a detecting means for processing the torque signal output from the magnetostrictive torque detecting means on the basis of the synchronizing signal to detect a torque fluctuation for each cylinder. And

In order to achieve the above object, the torque fluctuation measuring device for an internal combustion engine according to claim 2 is the torque fluctuation measuring device for an internal combustion engine according to claim 1, wherein the magnetic film is the flywheel surface. With a certain angular width within 1
It is characterized in that a pair is provided at a position facing each other by 80 °.

To achieve the above object, the torque fluctuation measuring device for an internal combustion engine according to claim 3 is the torque fluctuation measuring device for an internal combustion engine according to claim 2, wherein the magnetostrictive torque detecting means is the A pair is provided at a position facing the pair of magnetic films, and the detection means calculates an average of outputs from the pair of magnetostrictive torque detection means to obtain a torque signal.

In order to achieve the above object, the torque fluctuation measuring device for an internal combustion engine according to claim 4 is the torque fluctuation measuring device for an internal combustion engine according to claim 1, claim 2 or claim 3. The detecting means is characterized by having an integrating means for integrating a torque signal of each cylinder in a predetermined number of combustion cycles and a dispersion calculating means for calculating a statistical dispersion of integrated torque values in a predetermined number of combustion cycles.

In order to achieve the above object, the torque fluctuation measuring device for an internal combustion engine according to claim 5 is the torque fluctuation measuring device for an internal combustion engine according to claim 1, claim 2 or claim 3. The detection means has peak detection means for detecting a peak value of the torque signal of each cylinder in a predetermined number of combustion cycles, and dispersion calculation means for calculating a statistical dispersion of peak torque values in a predetermined number of combustion cycles. To do.

In order to achieve the above object, the torque fluctuation measuring device for an internal combustion engine according to claim 6 is the torque fluctuation measuring device for an internal combustion engine according to claim 1, further comprising:
Control means for controlling the fuel injection amount of each cylinder based on the torque fluctuation for each cylinder detected by the detection means is provided.

[0013]

In the torque fluctuation measuring apparatus for an internal combustion engine according to the present invention, a magnetic film is attached to the inside of a flywheel (or a drive plate in a vehicle with an automatic transmission), and the magnetostriction generated in the magnetic film is arranged at the rear portion of the engine block. It is detected by the magnetostrictive torque detecting means. In the conventional configuration in which the torque sensor is inserted after the propeller shaft to detect the torque,
Since the torque waveform is considerably dull due to the flywheel with a large inertial mass, the detected torque waveform is different from the actual torque waveform. By detecting the torque at the position, the combustion torque waveform due to the explosion of each cylinder can be accurately detected.

Further, by processing the torque waveform from the magnetostrictive torque detecting means using the crankshaft rotation synchronizing signal reflecting the combustion timing of each cylinder, it becomes possible to process the torque waveform at the combustion timing of each cylinder. ,
The torque fluctuation can be measured for each cylinder.

A pair of magnetic films of the present invention are provided at predetermined positions in the plane of the flywheel so as to face each other by 180 °, and each magnetic film is attached with a predetermined angular width. The crankshaft rotates with the combustion of each cylinder, and the relative positional relationship of the magnetic film with respect to the magnetostrictive torque detecting means changes. However, by using the synchronization signal indicating the rotation angle, the magnetic film is rotated by the magnetostrictive torque detecting means. The position opposite to can be easily determined. Therefore, if a pair of magnetic films are attached in advance on the flywheel surface at the position where the combustion torque peak value is detected, by processing the torque signal from the magnetostrictive torque detection means based on the synchronization signal, The vicinity of the torque peak value of the cylinder can be easily processed. For example, when the number of cylinders is 4, each cylinder completes one combustion cycle during the rotation of the crankshaft 720 °, so that four torque peaks appear during the rotation angle of 720 °. The torque peak is near the crankshaft angle of 25 ° (corresponding to the first cylinder), 205 ° (corresponding to the third cylinder), 385 ° (corresponding to the fourth cylinder) and 565 ° (corresponding to the second cylinder). It is considered that the pair of magnetic film adhesion positions in the flywheel plane are 25 ° at the crankshaft angle (corresponding to the first cylinder).
° (corresponding to the third cylinder), 385 ° (corresponding to the fourth cylinder),
If a magnetic film having a magnetic width of a predetermined angle width is attached around 565 ° (corresponding to the second cylinder) and the torque signal is processed at the timing of the angle based on the synchronization signal, the torque fluctuation for each cylinder can be reduced. It can be easily measured.

Here, in order to process the torque signal in the vicinity of the combustion torque peak and measure the torque fluctuation, a statistical dispersion indicating the degree of sample variation is used. That is, the obtained torque signal is integrated to calculate the statistical dispersion of the integrated value during a predetermined combustion cycle, or
The peak value of the obtained torque signal is detected and the statistical distribution of the peak value during a predetermined combustion cycle is calculated. Since the integrated torque value or the peak torque value is obtained for each cylinder, the variance for each cylinder is obtained.

In a magnetic head type sensor, the output generally fluctuates greatly due to fluctuations in clearance. Therefore, when only a single magnetostrictive detecting means is used, the torque may be detected in the flywheel which is considered to fluctuate in clearance. Accuracy matters. Therefore, in the present invention, a pair of magnetic films and magnetostrictive torque detecting means are provided at 180 ° opposite positions, and the average of the torque signals detected at each position is calculated to improve the detection accuracy. .

Further, according to the present invention, since the torque fluctuation for each cylinder can be measured, the lean limit can be accurately evaluated for each cylinder, and therefore the control means controls the fuel injection amount for each cylinder to prevent misfire. It becomes possible to do. This allows
It is also possible to improve drivability while reducing fuel consumption.

[0019]

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

<First Embodiment> FIG. 1 shows the configuration of the present embodiment. The engine of this embodiment is a 4-cylinder gasoline engine, and the combustion cylinders are arranged in the order of the first cylinder and the third cylinder.
Cylinder, fourth cylinder, second cylinder are in this order. In the figure, a flywheel 12 connected to a crankshaft 10
Rotation angle 30 in the plane of (drive plate in AT car)
Two magnetic films 14 having a width of 180 ° are attached to face each other by 180 °. The magnetic film attachment position will be described later. The flywheel 1 is the rear part of the engine block.
Two magnetostrictive torque sensors 16 are arranged at a position facing 2 to detect the magnetostriction generated in the magnetic film 14. The reason why the torque sensor 16 is of the two-head type is as follows.
In the magnetic head type sensor, the sensor characteristic greatly changes due to the variation of the clearance (gap between the sensor opening and the surface to be measured). Therefore, by outputting the average of two torque sensor outputs as a torque signal, the variation of the clearance to the sensor characteristic is This is to reduce the effect and stabilize the system. Further, the reason why the torque fluctuation is detected at the final position of the engine is to directly detect all the combustion torque waveforms due to the explosion of each cylinder as compared with the case where the torque sensor is inserted after the propeller shaft.

FIG. 2 shows the structure of the magnetostrictive torque sensor 16 in this embodiment, which is a sensor in which a U-shaped exciting coil and a detecting coil are arranged orthogonally to each other, and it is small but highly sensitive. Magnetostriction can be detected. The output from the torque sensor 16 is input to an analog signal processing circuit 18 as shown in FIG. 1, rectified into a DC signal proportional to torque, and then supplied to an A / D converter 20.

On the other hand, in the A / D converter 20, a 720 ° signal for generating a pulse once for two revolutions of the crankshaft is passed through a rotary encoder 24 as a synchronizing signal generating means, a waveform shaping circuit 26, and a frequency divider 28. And a 1 ° signal is provided which pulses 360 revolutions of the crankshaft. The position of the torque sensor 16 on the flywheel 12 surface can be monitored by the 1 ° signal.
Therefore, the timing at which the torque sensor 16 faces the adhesion region of the magnetic film 14 can be determined. On the other hand, 4
In the case of a cylinder engine, as shown in FIG. 3, one fuel cycle is completed during two revolutions of the crankshaft, and therefore four torque peaks corresponding to each cylinder are generated during the two revolutions of the crankshaft. As described above, the order of the combustion cylinders is the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.
The 20 ° signal makes it possible to determine which cylinder the torque signal currently detected is due to the explosion. Therefore, the A / D converter 20 converts the analog signal into digital data by using the 1 ° signal as a sampling timing signal, thereby converting the signal only in the region of the flywheel 12 to which the magnetic film 14 is attached to digital data. It is possible to determine which cylinder corresponds to the torque signal converted into digital data by the 720 ° signal.

The torque signal thus converted into digital data is stored in the memory and then input to the integrator 22. The 1 ° signal and the 720 ° signal described above are also input to the integrator 22, and integration processing of the instantaneous torque signal corresponding to each cylinder is performed. The integration section is the same as the adhesion region of the magnetic film 14, and for example, the adhesion region of the magnetic film 14 is 10 ° to 40 ° and 190 ° at a crank angle (TDC (top dead center) of the first cylinder is 0 °). When the positions corresponding to 220 °, 370 ° to 400 °, 550 ° to 580 ° are set, the integration interval is also the integration interval corresponding to the first cylinder: 10 ° to 40 ° The integration corresponding to the third cylinder Section: 190 ° -220 ° Integral section corresponding to the fourth cylinder: 370 ° -400 ° Integral section corresponding to the second cylinder: 550 ° -580 °. The width of the integration section is 30 °, of course, because the adhesion angle width of the magnetic film 14 is 30 °, and when the adhesion width of the magnetic film 14 is 5 ° or 10 °, the integration section also has a width of 30 °. Will be decided accordingly. Generally, the torque integrated value around 25 ° width most reflects the behavior of torque fluctuation in lean combustion.

When viewed from the rotation angle in the plane of the flywheel, the magnetic film adhesion region corresponding to the first cylinder, the magnetic film adhesion region corresponding to the third cylinder, and the magnetic film adhesion region corresponding to the fourth cylinder. Since the magnetic film adhering regions corresponding to the second cylinder are at the same positions, if the magnetic film 14 is adhered to two positions facing each other by 180 ° as shown in FIG.
~ All torque fluctuations in the fourth cylinder can be detected.

The integrator 22 performs the above-described integration processing over 100 combustion cycles, and the torque integrated value corresponding to each cylinder for 100 combustion cycles is stored in the data memory 30 and the integration for each cylinder is performed. The values are supplied to variance calculators 32, 34, 36 and 38, respectively. The dispersion calculators 32 to 38 calculate the dispersion value σ according to the following equation in order to evaluate the variation in the integrated torque value over 100 combustion cycles.

[Equation 1]

[Equation 2] The calculated variance value σ for each cylinder is supplied to the torque fluctuation value display 40, 42, 44, 46 for each cylinder, and the torque fluctuation is displayed.

FIG. 4 shows the relationship between the dispersion value of the integrated torque values thus calculated and the air-fuel ratio. The dispersion value tends to increase as the air-fuel ratio increases, which is consistent with the result of the conventional torque measurement device. further,
In this embodiment, the variance value of each cylinder, that is, the torque fluctuation is obtained. As shown in FIG. 4, when the air-fuel ratio is in the vicinity of 24, a large variation occurs between the cylinders, and the torque fluctuations of the first cylinder and the fourth cylinder are particularly large. The knowledge that it is large can also be obtained.

FIG. 5 shows a block diagram for controlling the fuel injection amount of each cylinder based on the variance value of the torque values corresponding to each cylinder, that is, the torque fluctuation value. The torque fluctuation information of each cylinder is sent from the variance calculation unit corresponding to each cylinder to the fuel injection amount control circuit, and further, the command signal of the fuel injection amount is sent from each injection amount control circuit to each injector, and the desired fuel is sent to each orbit. It will be injected independently.

As described above, in this embodiment, since the torque fluctuation can be measured for each cylinder, the fuel injection amount can be controlled so as to maintain the lean limit for each cylinder based on the measurement result. It becomes possible to further reduce the fuel consumption.

The torque sensor 16 in this embodiment is
Since it is provided at the rear part of the engine block as described above, it is possible to easily mount the sensor from the outside without making a great change in the engine block, and therefore the cost and durability are excellent.

Further, although the angle width of the magnetic film 14 is 30 ° in this embodiment, it can be set arbitrarily such as 15 ° or 45 °, and 5 ° etc. can be set especially when attention is paid to the torque peak value. Can be set to. Further, the combustion cycle can be arbitrarily set to not only 100 cycles but also 200 combustion cycles.

Further, in the present embodiment, the torque signal of only the magnetic film adhesion region is converted into digital data and integrated by the width of the magnetic film, but the magnetic film is adhered to the entire surface of the flywheel 12 and combustion of each cylinder is performed. It is also possible to detect the torque fluctuation for each cylinder by digitally converting the torque signal in synchronization with the timing and integrating it for a predetermined time.

<Second Embodiment> In the first embodiment described above,
The combustion torque signal in the magnetic film adhesion region in the flywheel (drive plate) 12 was integrated to calculate the integrated torque value for each cylinder. However, the peak torque value for each cylinder is obtained to evaluate the torque fluctuation. Is also possible.

FIG. 6 shows a configuration for detecting the peak torque value in this way. A difference from the configuration of FIG. 1 is that a peak calculator 23 is provided instead of the integrator 22, and the peak calculator 23 is specifically a peak hold circuit or the like. Then, the peak torque values for 100 combustion cycles detected for each cylinder are supplied to the variance calculators 32 to 38, and the variances of the peak values are calculated as torque fluctuations.

As described above, by using the peak hold circuit instead of the integrator, the torque fluctuation can be measured for each cylinder with a simpler structure than that of the first embodiment.

<Third Embodiment> In the first and second embodiments described above, the torque fluctuation was measured by calculating the variance of the integrated torque value or the peak torque value for each cylinder over 100 combustion cycles. It is also possible to measure the successive integrated torque value or the peak torque value for each combustion cycle.

FIG. 7 and FIG. 8 show the configuration for measuring the combustion state of each cylinder in each combustion cycle in real time. FIG. 7 shows the case where the integrated torque value of each cylinder is measured. The difference from FIG. 1 is that the integrated torque value of each cylinder calculated by the integrator 22 is sequentially displayed for each combustion cycle. This is the point supplied to and displayed on the containers 50 to 56. Further, FIG. 8 is a case where the peak torque value of each cylinder is measured, and the point different from FIG. 6 is the peak calculator 23.
It is a point that the peak torque value for each cylinder calculated in step 1 is sequentially supplied and displayed on the peak value indicators 60 to 66 for each combustion cycle. FIG. 9 is a graph showing a case where the air-fuel ratio A / F of the first cylinder is set to 14.5 and 24 in the configuration of FIG.
The results of detecting peak torque values over the combustion cycle are shown. From the figure, in the case of the air-fuel ratio 14, the combustion is stable in each combustion cycle, so the torque peak value maintains a substantially constant value, but in the case of the air-fuel ratio 23, it becomes 1
It can be seen that the torque peak value decreases about once every 0 to 20 combustion cycles. This decrease in the peak torque value is considered to be due to a misfire and occurs randomly.

Although only the combustion state of the first cylinder is shown in the figure, the combustion states of the other cylinders are the same, and the combustion states of the four cylinders can be simultaneously monitored in real time.

[0038]

As described above, according to the torque fluctuation measuring device for an internal combustion engine according to claims 1 to 6, in the internal combustion engine having a plurality of cylinders, the torque fluctuation of each cylinder can be easily and reliably obtained. Can be measured.

In particular, according to the torque fluctuation measuring device for an internal combustion engine of claim 6, the fuel injection amount can be adjusted for each cylinder based on the torque fluctuation of each cylinder, so that misfire or the like in a lean burn state can be prevented. It is possible to obtain good drivability with low fuel consumption.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a first embodiment of the present invention.

FIG. 2 is a perspective view of a magnetostrictive torque sensor according to the same embodiment.

FIG. 3 is a graph showing a relationship between a crankshaft angle and a sensor output in the example.

FIG. 4 is a graph showing the relationship between the dispersion of integrated torque values and the air-fuel ratio in the same example.

FIG. 5 is a configuration block diagram of a first embodiment of the present invention.

FIG. 6 is a configuration block diagram of a second embodiment of the present invention.

FIG. 7 is a configuration block diagram of a third embodiment of the present invention.

FIG. 8 is another configuration block diagram of the third embodiment of the present invention.

FIG. 9 is a graph showing a relationship between a combustion cycle and a torque peak value when the air-fuel ratio of the example is changed.

FIG. 10 is a graph showing the relationship between the air-fuel ratio and the fuel consumption and torque fluctuations.

[Explanation of symbols]

 10 crankshaft 12 flywheel (drive plate) 14 magnetic film 16 torque sensor 18 analog signal processing circuit 20 A / D converter 22 integrator 23 peak calculator 24 rotary encoder 26 waveform shaping circuit 28 frequency divider 30 data memory 32, 34, 36, 38 variance calculator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Nishibe, Nagakute-cho, Aichi-gun, Aichi Prefecture 1-41 Yokochi, Yokosuka Central Research Institute Co., Ltd. (72) Inventor, Hiroshi Nonomura Nagakute-cho, Aichi-gun 41, Yokoshiro Road Inside Toyota Central Research Institute Co., Ltd.

Claims (6)

[Claims] 1. A magnetic film attached to a surface of a flywheel connected to crankshafts of a plurality of cylinders, a magnetostrictive torque detecting means provided at a position facing the magnetic film in an engine block rear portion, and a crank. Sync signal generating means for generating a sync signal in synchronism with the rotation of the shaft; and detecting means for processing the torque signal output from the magnetostrictive torque detecting means based on the sync signal to detect torque fluctuation for each cylinder. A torque fluctuation measuring apparatus for an internal combustion engine, comprising: 2. The torque fluctuation measuring device for an internal combustion engine according to claim 1, wherein a pair of the magnetic films are provided at positions facing each other with a predetermined angular width in the plane of the flywheel. Fluctuation measuring device for internal combustion engine. 3. The torque fluctuation measuring device for an internal combustion engine according to claim 2, wherein a pair of the magnetostrictive torque detecting means is provided at a position facing the pair of magnetic films, and the detecting means is the pair of magnetostrictive torque detecting means. A torque fluctuation measuring device for an internal combustion engine, wherein an average of outputs from the torque detecting means is calculated and used as a torque signal. 4. Claim 1 or claim 2 or claim 3.
In the torque fluctuation measuring device for an internal combustion engine as described above, the detecting means calculates an integral means for integrating a torque signal of each cylinder in a predetermined number of combustion cycles, and a statistical dispersion of integrated torque values in the predetermined number of combustion cycles. A torque fluctuation measuring device for an internal combustion engine, comprising: dispersion calculating means. 5. Claim 1 or claim 2 or claim 3.
In the torque fluctuation measuring device for an internal combustion engine as described above, the detecting means is a peak detecting means for detecting a peak value of a torque signal of each cylinder in a predetermined number of combustion cycles, and a statistical value of a peak torque value in a predetermined number of combustion cycles. A torque fluctuation measuring device for an internal combustion engine, comprising: a dispersion calculating means for calculating the dispersion. 6. The torque fluctuation measuring device for an internal combustion engine according to claim 1, further comprising control means for controlling the fuel injection amount of each cylinder based on the torque fluctuation of each cylinder detected by the detecting means. A torque fluctuation measuring device for an internal combustion engine, comprising: