JP2000170589A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine for correctly operating data effective to control the engine, besides reducing a load for operation processing. SOLUTION: In a control device having a cylinder pressure sensor 13 for detecting pressure in the cylinder of an internal combustion engine, and a sampling means 20 for sampling a cylinder pressure signal from the sensor 13 at every given interval, and controlling the engine based on the signal sampled by the means 20; an interval in sampling intervals can be compensated by interpolations through shortening sampling intervals in a range difficult to correct interpolation based on a small number of actual measured values of cylinder pressure, and prolonging the sampling intervals in a range capable of correct compensation based on the small number of measured values of cylinder pressure; by providing a sampling interval changing means 25 for changing sampling intervals for cylinder pressure signals by means of the means 20 in accordance with the crank angular position of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine control device capable of reducing the load of arithmetic processing.

[0002]

2. Description of the Related Art An internal combustion engine control device has a cylinder pressure sensor for detecting a pressure in a cylinder of an internal combustion engine, and sampling means for sampling a cylinder pressure signal from the cylinder pressure sensor at predetermined intervals. There is one that calculates a charging efficiency based on the in-cylinder pressure signal sampled by the sampling means and controls the internal combustion engine based on the charging efficiency (for example, Japanese Patent Application Laid-Open No. Hei 6-146995). However, this type of internal combustion engine control apparatus conventionally samples the in-cylinder pressure at predetermined equally spaced crank angle positions. Specifically, there is known one which samples the in-cylinder pressure at a timing of every 30 degrees of the crank angle (12 pulses at 360 degrees).

[0003]

In the case of sampling the in-cylinder pressure at the timing of every 30 degrees of the crank angle as described above, the number of samplings is not sufficient, and the internal combustion engine such as charging efficiency or average effective pressure is not sufficient. However, there is a problem that effective data for the control cannot be accurately calculated. For this reason, it was considered to sample the in-cylinder pressure at the timing of every 1 ° of the crank angle (360 pulses at 360 °). However, with such multi-pulse sampling, especially when the engine speed is high, the sampling cycle with respect to time is shortened, and the time that can be allocated to the arithmetic processing is shortened. It was expected that a problem that the size would increase.

An object of the present invention is to provide an internal combustion engine control device that can accurately calculate effective data for controlling an internal combustion engine and can reduce the load of arithmetic processing.

[0005]

According to a first aspect of the present invention, there is provided an internal combustion engine control apparatus for detecting a pressure in a cylinder of an internal combustion engine.
The in-cylinder pressure sensor 13) according to the embodiment of the invention, and sampling means (for example, the sampling unit 20 in the embodiment of the invention) for sampling the in-cylinder pressure signal from the in-cylinder pressure sensor. Controlling the internal combustion engine based on the obtained in-cylinder pressure signal, and changing the sampling interval of the in-cylinder pressure signal by the sampling means according to the crank angle position of the internal combustion engine (for example,
Sampling interval changing unit 2 in the embodiment of the invention
5) is provided.

As described above, since the sampling interval changing means changes the sampling interval of the in-cylinder pressure signal by the sampling means in accordance with the crank angle position of the internal combustion engine, accurate interpolation based on a small number of measured in-cylinder pressure values can be achieved. By shortening the sampling interval in a difficult range, and increasing the sampling interval in a range where accurate interpolation based on a small number of measured values of in-cylinder pressure is possible, and supplementing the sampling interval with interpolation,
The calculation processing load can be reduced without sacrificing the accuracy of the calculation of the data effective for controlling the internal combustion engine.

According to a second aspect of the present invention, there is provided the internal combustion engine control device according to the first aspect, wherein the sampling interval changing means is configured such that the crank angle position is within a predetermined range before or after a top dead center or a bottom dead center. If it is within a predetermined range before and after the point, the sampling interval of the in-cylinder pressure by the sampling means is set to a short first interval, and the crank angle position is not within the predetermined range before and after the top dead center and is lower. If it is not within the predetermined range before and after the dead center and is between the bottom dead center of intake and the top dead center of compression or between the top dead center of compression and the bottom dead center of explosion, the in-cylinder pressure by the sampling means The sampling interval of the second interval longer than the first interval, further, the crank angle position is not within the predetermined range before and after the top dead center and not within the predetermined range before and after the bottom dead center, Intake bottom dead center If it is not between the compression top dead center and the compression top dead center and between the compression top dead center and the explosion bottom dead center, the sampling interval of the in-cylinder pressure by the sampling means is set to a third interval longer than the second interval. It is characterized in that.

As described above, the sampling interval changing means determines whether or not the crank angle position is within a predetermined range before and after the top dead center or within a predetermined range before and after the bottom dead center, that is, based on a small measured value of the in-cylinder pressure. If the accurate interpolation is in a range where it is difficult, the sampling interval of the in-cylinder pressure by the sampling means is set to a short first interval, and the crank angle position is not within a predetermined range before and after the top dead center and the bottom dead center is not set. If it is not within the predetermined range before and after, and is between the bottom dead center of the intake and the top dead center of the compression or between the top dead center of the compression and the bottom dead center of the explosion, When the interpolation is in a range where the interpolation is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to a second interval longer than the first interval, and the crank angle position is not within a predetermined range before and after the top dead center and Be within a predetermined range before and after the dead centers, if not until the explosion bottom dead center from and compression top dead center without until compression top dead center from the bottom dead center of the intake stroke, i.e.,
When the accurate interpolation based on a smaller number of actually measured values of the in-cylinder pressure is in a range where it is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to a third interval longer than the second interval. Therefore, the sampling interval can be accurately changed according to the reliability of the interpolation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the internal combustion engine control device 10 detects a negative pressure in an intake pipe of an internal combustion engine (not shown) and outputs a negative pressure signal in accordance with the negative pressure.
A rotation angle detection device 12 for detecting a rotation angle of a crankshaft of the internal combustion engine and outputting a crank angle position signal corresponding thereto every 1 ° of the crankshaft; and detecting and detecting a pressure in a cylinder of the internal combustion engine. It has an in-cylinder pressure sensor 13 that outputs a corresponding in-cylinder pressure signal, and a control unit 14 to which signals from the negative pressure sensor 11, the rotation angle detection device 12, and the in-cylinder pressure sensor 13 are introduced.

The control unit 14 includes an injector 16 for supplying fuel to a cylinder of the internal combustion engine, an igniter 17 for igniting in the cylinder of the internal combustion engine, and recirculating exhaust gas from an exhaust pipe of the internal combustion engine to an intake pipe. The control unit 14 is connected to an exhaust gas recirculation device 18, based on information from the negative pressure sensor 11, the rotation angle detection device 12, and the in-cylinder pressure sensor 13. Based on these, the timing of starting fuel supply by the injector 16 and the fuel supply amount, the ignition timing by the ignition device 17, the amount of exhaust gas recirculation by the exhaust gas recirculation device 18, and the like are controlled. When the internal combustion engine has a plurality of cylinders, the in-cylinder pressure sensor 13, the injector 16, and the ignition device 17 are provided for each cylinder.

The control unit 14 is connected to the in-cylinder pressure sensor 13 and samples the in-cylinder pressure signal introduced from the in-cylinder pressure sensor 13 at predetermined intervals. An average effective pressure and a pumping loss of the internal combustion engine are calculated based on the sampled in-cylinder pressure signal, and a crank angle position signal introduced from the rotation angle detector 12 and a negative pressure introduced from the negative pressure sensor 11 are calculated. Based on signals, etc.
CP that controls the injector 16, the ignition device 17, and the exhaust gas recirculation device 18 (that is, controls the internal combustion engine)
U2, a ROM 22 storing a map of control amounts of the injector 16, the ignition device 17, and the exhaust gas recirculation device 18 corresponding to the calculation result of the CPU 21, and the like;
And a RAM 23 for storing the result of the operation of the first step.

In this embodiment, the control unit 14 changes the sampling interval of the in-cylinder pressure signal by the sampling unit 20 in accordance with the crank angle position signal introduced from the rotation angle detecting device 12. (Sampling interval changing means) 25.

When the crank angle position is within a predetermined range before and after TDC (piston top dead center) or within a predetermined range before and after BDC (piston bottom dead center), the sampling interval changing unit 25 performs sampling. The sampling interval of the in-cylinder pressure by 20 is a short first interval.

In addition, the sampling interval changing unit 25 detects that the intake angle BD is not within the predetermined range before and after TDC and within the predetermined range before and after BDC.
Explosion B from C to compressed TDC or from compressed TDC
If it is before DC, the sampling interval of the in-cylinder pressure by the sampling unit 20 is set to the second interval longer than the first interval.
The interval of.

Further, the sampling interval changing unit 25
When the crank angle position is not within the predetermined range before and after TDC and not within the predetermined range before and after BDC, the intake air B
If it is not between DC and compressed TDC and between compressed TDC and explosion BDC, the sampling unit 2
The sampling interval of the in-cylinder pressure by 0 is set to a third interval longer than the second interval.

Here, the predetermined range before and after is a range in which accurate interpolation based on a small number of measured values of the in-cylinder pressure is certainly difficult, and specifically, is set to a range within ± 15 ° of TDC or BDC. Have been. Further, the first interval is set to 1 ° interval which is the minimum interval of the crankshaft which can be detected by the rotation angle detecting means, and the second interval is set to 3 ° interval which is larger than the first interval. In this case, the third interval is set to be 10 ° larger than the second interval.

The internal combustion engine control apparatus 10 having the above configuration
Will be described with reference to the flowcharts of FIGS. As shown in FIG.
In step S1, a crank angle position signal is introduced from the rotation angle detector 12 and a negative pressure signal is introduced from the negative pressure sensor 11, and in-cylinder pressure sampling processing is performed in step S2. That is, in step S2, the sampling interval changing unit 25 performs the following in-cylinder pressure sampling process shown in FIG. 3 for each 1 ° of the crank angle determined from the crank angle position signal introduced from the rotation angle detection device 12. Execute

In step S2-1, the sampling interval changing unit 25 determines that the current crank angle is within ± TDC.
It is determined whether it is within 15 ° or within ± 15 ° from BDC, and within ± 15 ° from TDC or ±
If the angle is within 15 °, it is a range in which accurate interpolation based on a small number of measured values of the in-cylinder pressure is definitely difficult, and it is necessary to calculate the average effective pressure and the pumping loss based on all the measured values. In step S2-2, the in-cylinder pressure signal is sampled every 1 ° of the crank angle determined from the crank angle position signal by the sampling unit 20.

That is, as shown by ranges X1 to X4 in FIG. 4, when the current crank angle is within ± 15 ° from TDC or ± 15 ° from BDC, the combustion chamber volume V and the in-cylinder pressure P Is a range in which the relationship is suddenly changed and a fixed relationship cannot be obtained, so that it is determined that accurate interpolation based on a small number of measured values of the in-cylinder pressure is difficult.

In step S2-1, if the current crank angle is not within ± 15 ° of TDC and BD
If not within ± 15 ° from C, step S2-3
, The current crank angle is changed from the intake BDC to the compression T
DC or from the compression TDC to the explosion BDC to determine whether the current crank angle is the intake BD
Explosion B from C to compressed TDC or from compressed TDC
If it is up to DC, it is within a range where accurate interpolation based on a small number of measured values of the in-cylinder pressure is possible, and it is possible to calculate the average effective pressure and the pumping loss based on the measured values and the interpolation data. In step S2-4, the sampling unit 20 is caused to sample the in-cylinder pressure signal every 3 ° of the crank angle calculated from the crank angle position signal.

That is, as shown by ranges X5 and X6 in FIG. 4, when the current crank angle is not within ± 15 ° from TDC and ± 15 ° from BDC,
In the case between the intake BDC and the compression TDC or between the compression TDC and the explosion BDC, as shown in FIG. 5, the logarithm of the combustion chamber volume logV and the logarithm of the in-cylinder pressure logP
Is a proportional relationship, and a polytropic index (logP / log) which is a constant derived from the proportional relationship
From V), accurate interpolation between actual measured values is possible even with a small number of actual measured values, so the sampling interval is widened and the in-cylinder pressure signal is sampled every 3 ° of the crank angle.

Further, in step S2-3, if the current crank angle is not between the intake BDC and the compression TDC and between the compression TDC and the explosion BDC, it is based on a smaller number of actually measured in-cylinder pressures. In step S2-5, the sampling unit 20 is determined to be in a range where accurate interpolation is possible and the average effective pressure and the pumping loss can be calculated based on the actually measured value and the interpolation data.
, The in-cylinder pressure signal is sampled every 10 degrees of the crank angle determined from the crank angle position signal.

That is, as shown by ranges X7 and X8 in FIG. 4, when the current crank angle is not within ± 15 ° from TDC and not within ± 15 ° from BDC,
Not between the intake BDC and the compression TDC and the compression TD
When the pressure is not between C and the explosion BDC, the in-cylinder pressure P becomes almost constant, and even if a small number of measured values can be accurately interpolated between the measured values, the sampling interval can be further extended to increase the crank angle. The in-cylinder pressure signal is sampled every 10 °.

Then, as shown in FIG. 2, step S3
In the in-cylinder pressure sampling process, the CPU 21 determines that the temperature is within ± 15 ° from TDC or ± 15 ° from BDC.
If it is within ゜, the average effective pressure and the pumping loss are calculated from only the measured values of the in-cylinder pressure based on all the sampled in-cylinder pressure signals.

In the cylinder pressure sampling process,
CP within ± 15 ° from TDC and ± 15 ° from BDC and between intake BDC and compression TDC or between compression TDC and explosion BDC
U21 calculates the average effective pressure and the pumping loss based on the measured values of the in-cylinder pressure based on all the sampled in-cylinder pressure signals and the interpolation data predicted by the polytropic index.

Further, in the in-cylinder pressure sampling process, it is not within ± 15 ° from TDC and ± 1 ° from BDC.
If it is not within 5 °, and it is not between the intake BDC and the compression TDC, and not between the compression TDC and the explosion BDC, the CPU 21 determines the measured value of the in-cylinder pressure based on all the sampled in-cylinder pressure signals. An average effective pressure and a pumping loss are calculated based on interpolation data predicted from actual measurement values before and after.

The CPU 21 calculates the average effective pressure when the sampling from the intake BDC to the explosion BDC is completed, and calculates the pumping loss when the sampling from the explosion BDC to the intake BDC is completed. . Further, the CPU 21 resets the sampling data of the in-cylinder pressure used in the calculation of the average effective pressure at the time when the average effective pressure is calculated so that a new sampling can be performed. Is reset so that new sampling can be performed.

In step S4, the fuel injection amount by the injector 16, the exhaust gas recirculation amount (EGR amount) by the exhaust gas recirculation device 18, and the ignition device 17 are determined based on the average effective pressure and the pumping loss calculated in this manner. The ignition timing is controlled by each of them.

According to the internal combustion engine control device 10 described above, the sampling interval changing unit 25 of the control unit 14 changes the sampling interval of the in-cylinder pressure signal by the sampling unit 20 according to the crank angle position of the internal combustion engine. Therefore, the sampling interval is shortened in a range where accurate interpolation based on a small number of measured values of in-cylinder pressure is difficult, and the sampling interval is lengthened in a range where accurate interpolation based on a small number of measured values of in-cylinder pressure is possible. By supplementing the interval by interpolation, the CPU 21 can accurately calculate the average effective pressure and the pumping loss, which are data effective for controlling the internal combustion engine, and can reduce the load of the calculation processing of the CPU 21. In particular, a high effect can be obtained at a high rotation speed where the processing time is limited.

Further, the sampling interval changing unit 25 determines that the crank angle position is within a predetermined range before and after TDC or BD.
If it is within a predetermined range before and after C, that is, if it is in a range where accurate interpolation based on a small number of measured values of the in-cylinder pressure is difficult, the sampling interval of the in-cylinder pressure by the sampling means is set to a short first interval; , Crank angle position is TD
C is not within the predetermined range before and after C and is not within the predetermined range before and after BDC and is between the intake BDC and the compression TDC or between the compression TDC and the explosion BDC; When the accurate interpolation based on the actual measurement value is in a range where accurate interpolation is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to a second interval longer than the first interval, and the crank angle position is set to a predetermined value before and after the TDC. When it is not within the range and not within the predetermined range before and after the BDC, and is not between the intake BDC and the compression TDC and between the compression TDC and the explosion BDC, that is, a smaller measured value of the in-cylinder pressure. In the case where accurate interpolation based on the above is within a range where sampling is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to a third interval longer than the second interval.

Therefore, since the sampling interval can be accurately changed in accordance with the certainty of the interpolation, the accuracy of calculating the average effective pressure and the pumping loss, which are effective data for controlling the internal combustion engine, is sacrificed. Therefore, it is possible to surely reduce the load of the arithmetic processing.

Moreover, the sampling interval changing unit 25
± 15 ° is set as the predetermined range before and after, and when the crank angle position is within ± 15 ° of TDC or ± 15 ° of BDC, that is, accurate interpolation based on a small number of actually measured in-cylinder pressures is performed. In the case where it is surely within the difficult range, the sampling interval of the in-cylinder pressure by the sampling means is set to the short first interval, so that the accuracy of the calculation is not sacrificed without fail. Therefore, the CPU 21 can calculate the average effective pressure and the pumping loss more accurately.

[0033]

As described in detail above, claim 1 of the present invention
According to the internal combustion engine control device described above, the sampling interval changing means changes the sampling interval of the in-cylinder pressure signal by the sampling means in accordance with the crank angle position of the internal combustion engine. In the range where difficult interpolation is difficult, the sampling interval is shortened, and in the range where accurate interpolation based on a small number of measured in-cylinder pressures is possible, the sampling interval is extended and interpolation between sampling intervals is used to control the internal combustion engine. Effective data can be accurately calculated, and the load of calculation processing can be reduced.

According to the internal combustion engine control device of the second aspect of the present invention, the sampling interval changing means sets the crank angle position within a predetermined range before and after the top dead center or within a predetermined range before and after the bottom dead center. In other words, in a case where accurate interpolation based on a small number of measured values of the in-cylinder pressure is in a range where it is difficult, the sampling interval of the in-cylinder pressure by the sampling means is set to be short.
The crank angle position is not within a predetermined range before and after the top dead center, and is not within a predetermined range before and after the bottom dead center. In the case between the dead center and the bottom dead center of the explosion, that is, in a range where accurate interpolation based on a small number of measured values of the in-cylinder pressure is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to the first interval. A longer second interval, and
The crank angle position is not within the predetermined range before and after top dead center and not within the predetermined range before and after bottom dead center, and it is not between intake bottom dead center and compression top dead center and explodes from compression top dead center. If the interval is not before the bottom dead center, that is, if accurate interpolation based on a smaller number of actually measured values of the in-cylinder pressure is in a range where it is possible, the sampling interval of the in-cylinder pressure by the sampling means is set to be smaller than the second interval. Make a long third interval. Therefore, since the sampling interval can be accurately changed in accordance with the reliability of the interpolation, the load of the arithmetic processing can be surely reduced without sacrificing the accuracy of the arithmetic.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an internal combustion engine control device according to an embodiment of the present invention;

FIG. 2 is a main flowchart showing control contents of one embodiment of the internal combustion engine control device of the present invention.

FIG. 3 is a flowchart of an in-cylinder pressure sampling process according to an embodiment of the internal combustion engine control device of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a cylinder pressure P (vertical axis) and a combustion chamber volume V (horizontal axis) of the internal combustion engine.

FIG. 5: Between intake BDC and compression TDC or compression TDC
FIG. 9 is a characteristic diagram showing a relationship between a logarithm logV (horizontal axis) of a combustion chamber volume and a logarithm logP (vertical axis) of in-cylinder pressure between explosion BDC.

[Explanation of symbols]

Reference Signs List 10 internal combustion engine control device 13 in-cylinder pressure sensor 20 sampling unit (sampling unit) 25 sampling interval changing unit (sampling interval changing unit)

Continued on the front page (72) Inventor Hidenori Akiyama 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G084 BA13 BA17 BA20 EA05 EB26 FA21 FA38 FA39

Claims (2)

[Claims] 1. An in-cylinder pressure sensor for detecting a pressure in a cylinder of an internal combustion engine, and sampling means for sampling an in-cylinder pressure signal from the in-cylinder pressure sensor, wherein the in-cylinder pressure signal sampled by the sampling means is provided. An internal combustion engine control device that controls an internal combustion engine based on the internal combustion engine, further comprising: a sampling interval changing unit that changes a sampling interval of the in-cylinder pressure signal by the sampling unit according to a crank angle position of the internal combustion engine. Control device. 2. The cylinder pressure sampling interval of the in-cylinder pressure when the crank angle position is within a predetermined range before and after top dead center or within a predetermined range before and after bottom dead center. And a short first interval, and the crank angle position is not within the predetermined range before and after the top dead center and not within the predetermined range before and after the bottom dead center,
In the case between the bottom dead center of intake and the top dead center of compression or between the top dead center of compression and the bottom dead center of explosion, the sampling interval of the in-cylinder pressure by the sampling means is set to the second interval longer than the first interval. Further, the crank angle position is not within the predetermined range before and after the top dead center and not within the predetermined range before and after the bottom dead center, and between the intake bottom dead center and the compression top dead center. When the pressure is not between the compression top dead center and the explosion bottom dead center, the sampling interval of the in-cylinder pressure by the sampling means is set to a third interval longer than the second interval. An internal combustion engine control device according to claim 1.