JP2018172994A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further reduce processing load in controlling an internal combustion engine while maintaining determination accuracy for occurrence of anomaly of the internal combustion engine.SOLUTION: In an internal combustion engine control device 10, a sampling interval change part 36 calculates a cylinder internal pressure rising rate DP based on cylinder internal pressure Pi and a crank angle CA and, when the calculated cylinder internal pressure rising rate DP goes out from a predetermined pressure change rate range (AL≤DP≤AH) in a range of the predetermined crank angle CA, shortens a sampling interval for a cylinder internal pressure signal at a sampling part 34.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine controller that controls an internal combustion engine based on the pressure in a combustion chamber.

  In an internal combustion engine, after ignition, the pressure in the combustion chamber (cylinder pressure) increases. In this case, knocking may occur if the in-cylinder pressure rapidly increases due to premature combustion due to premature ignition. On the other hand, if the combustion is slow, misfire may occur. Therefore, it is necessary to detect (determine) the occurrence of an abnormality in the internal combustion engine such as knocking or misfire, and to properly control the internal combustion engine based on the detection result, so that a normal combustion state is required.

  For example, in Patent Document 1, in a predetermined rotation angle range in which the in-cylinder pressure and volume of the combustion chamber change rapidly, the sampling interval for the in-cylinder pressure signal corresponding to the in-cylinder pressure detected by the in-cylinder pressure sensor is shortened. It is disclosed that data effective for control of an internal combustion engine is accurately calculated and the load of calculation processing is reduced.

JP 2000-170589 A

  However, in the technique of Patent Document 1, even when no abnormality occurs in the internal combustion engine, the sampling interval is necessarily shortened in the above rotation angle range, so that the processing burden is wasted and there is room for improvement.

  Therefore, an object of the present invention is to provide an internal combustion engine control device that can further reduce the processing load on the control of the internal combustion engine while maintaining the determination accuracy with respect to the occurrence of abnormality in the internal combustion engine.

  An internal combustion engine control device (10) according to the present invention includes a pressure sensor (16) for detecting a pressure (Pi) in a combustion chamber (14) of an internal combustion engine (12), and the pressure sensor (16) detecting the pressure sensor (16). A sampling unit (34) for sampling a pressure signal corresponding to the pressure (Pi); and a control unit (26) for controlling the internal combustion engine (12) based on the sampled pressure signal. It has the characteristics of.

  1st characteristic; The said internal combustion engine control apparatus (10) further has a rotation angle sensor (20) and a sampling interval change part (36). The rotation angle sensor (20) detects a rotation angle (CA) of the internal combustion engine (12). The sampling interval changing unit (36) calculates a pressure change rate (DP) of the pressure (Pi) with respect to the rotation angle (CA) based on the pressure (Pi) and the rotation angle (CA), When the calculated pressure change rate (DP) is outside the predetermined pressure change rate range in the rotation angle range, the sampling interval for the pressure signal in the sampling unit (34) is shortened.

  2nd characteristic; The said rotation angle range is a range of the rotation angle (CA) after the ignition of the said internal combustion engine (12).

  Third feature: The rotation angle range is a range including a rotation angle (CA) at a top dead center of the internal combustion engine (12).

  4th characteristic; The said sampling interval change part (36) calculates the rotation speed of the said internal combustion engine (12) based on the said rotation angle (CA), and the said pressure change rate range according to the calculated said rotation speed Adjust.

  Fifth feature; the sampling interval changing unit (36) changes the sampling interval to 10 ° or less when the pressure change rate (DP) is out of the pressure change rate range.

  6th characteristic; The said internal combustion engine control apparatus (10) further has the temperature sensor (22) which detects the temperature (Tw) of the said internal combustion engine (12). In this case, the sampling interval changing unit (36) shortens the sampling interval when the temperature (Tw) exceeds a predetermined temperature threshold (Twth).

  7th characteristic; The said internal combustion engine control apparatus (10) further has a throttle opening sensor (24) which detects the throttle opening (TH) of the said internal combustion engine (12). In this case, the sampling interval changing unit (36) shortens the sampling interval when the throttle opening (TH) exceeds a predetermined throttle opening threshold (THth).

  Eighth feature: the pressure sensor (16) is disposed in the combustion chamber (14) at a position spaced from the cam chamber (44) of the internal combustion engine (12) and close to the spark plug (40). Has been.

  According to the first feature of the present invention, since the sampling interval is shortened only when the pressure change rate is out of the pressure change rate range, the processing burden on the control unit can be reduced. Also, when an internal combustion engine abnormality such as knocking or misfire occurs, the pressure change rate may fall outside the pressure change rate range, so control can be performed by shortening the sampling interval and sampling the pressure signal finely. The determination accuracy with respect to the abnormality of the internal combustion engine at the section can be increased. Therefore, in the first feature, it is possible to further reduce the processing load for the control of the internal combustion engine while maintaining the determination accuracy for the abnormality of the internal combustion engine as compared with the technique of Patent Document 1.

  According to the second feature of the present invention, since the rotation angle range is limited after ignition, the determination accuracy for abnormality of the internal combustion engine is improved.

  Further, at the rotation angle near the top dead center, the pressure change rate tends to deviate from the pressure change rate range due to the occurrence of abnormality of the internal combustion engine such as knocking or misfire. Therefore, in the third feature of the present invention, it is possible to improve the determination accuracy for the abnormality of the internal combustion engine by setting the rotation angle range so as to include the rotation angle of the top dead center.

  According to the fourth feature of the present invention, the determination accuracy for abnormality of the internal combustion engine can be further improved by setting an appropriate pressure change rate range based on the rotational speed of the internal combustion engine.

  According to the fifth feature of the present invention, by changing the sampling interval to 10 ° or less, sufficient determination accuracy can be ensured for an abnormality of the internal combustion engine.

  According to the sixth aspect of the present invention, it is possible to improve the determination accuracy for abnormality of the internal combustion engine by shortening the sampling interval based on the temperature of the internal combustion engine.

  According to the seventh feature of the present invention, it is possible to improve the determination accuracy for abnormality of the internal combustion engine by shortening the sampling interval based on the throttle opening.

  According to the eighth aspect of the present invention, the influence of noise on the pressure detected by the pressure sensor can be reduced.

1 is a block diagram of an internal combustion engine control device according to an embodiment. It is explanatory drawing which illustrated the attachment position of the acupressure sensor in a combustion chamber. 2 is a flowchart illustrating an operation of the internal combustion engine control device of FIG. 1. FIG. 4A is a graph showing a change in the in-cylinder pressure with respect to the crank angle, and FIG. 4B is a graph showing a change in the in-cylinder pressure increase rate with respect to the crank angle.

  An internal combustion engine control apparatus according to the present invention will be described in detail below with reference to the accompanying drawings by listing preferred embodiments.

[Configuration of Internal Combustion Engine Control Device 10]
FIG. 1 is a block diagram of an internal combustion engine control apparatus 10 according to the present embodiment. FIG. 2 is an explanatory diagram illustrating the attachment position of the finger pressure sensor (pressure sensor) 16 in the combustion chamber 14 of the internal combustion engine 12 controlled by the internal combustion engine control device 10 in plan view.

  The internal combustion engine control device 10 includes a finger pressure sensor 16, a negative pressure sensor 18, a rotation angle sensor 20, a temperature sensor 22, a throttle opening sensor 24, and an ECU (Engine Control Unit) 26.

  The finger pressure sensor 16 sequentially detects an in-cylinder pressure (pressure) Pi in the combustion chamber 14 of the internal combustion engine 12 and sequentially outputs an in-cylinder pressure signal (pressure signal) corresponding to the detected in-cylinder pressure Pi. The negative pressure sensor 18 sequentially detects a negative pressure in an intake pipe (not shown) of the internal combustion engine 12 and sequentially outputs a negative pressure signal corresponding to the detected negative pressure to an ECU (control unit) 26. The rotation angle sensor 20 detects the rotation angle (crank angle) CA of the crankshaft of the internal combustion engine 12 at predetermined angular intervals, and sequentially outputs a crank signal (rotation angle signal) corresponding to the detected crank angle CA to the ECU 26. . The temperature sensor 22 sequentially detects the temperature Tw of the internal combustion engine 12 (for example, the temperature of the cooling water or the oil temperature of the lubricating oil), and sequentially outputs a temperature signal corresponding to the detected temperature Tw to the ECU 26. The throttle opening sensor 24 sequentially detects the throttle opening TH of a throttle valve (not shown) disposed in the middle of the intake pipe, and sequentially outputs a throttle opening signal corresponding to the detected throttle opening TH to the ECU 26.

  The ECU 26 includes a CPU (Central Processing Unit) 28, and the CPU 28 reads out and executes a program stored in a ROM (Read Only Memory) 30, whereby the finger pressure sensor 16, the negative pressure sensor 18, the rotation angle sensor 20 The internal combustion engine 12 is controlled based on various signals input from the temperature sensor 22 and the throttle opening sensor 24.

  Specifically, the ECU 26 includes a CPU 28, a ROM 30, a RAM (Random Access Memory) 32, a sampling unit 34, and a sampling interval changing unit 36.

  The sampling unit 34 samples the in-cylinder pressure signal sequentially input from the finger pressure sensor 16 at a predetermined sampling interval (interval of the crank angle CA for sampling the in-cylinder pressure signal), and samples the in-cylinder pressure signal (in-cylinder pressure Pi). ) Is output to the CPU 28. The sampling interval changing unit 36 changes the in-cylinder pressure Pi with respect to the crank angle CA based on the in-cylinder pressure signal (in-cylinder pressure Pi) sequentially input from the finger pressure sensor 16 and the crank signal sequentially input from the rotation angle sensor 20. The rate (in-cylinder pressure increase rate, pressure change rate) DP is calculated, and the sampling interval is changed based on the calculated in-cylinder pressure increase rate DP. Further, the sampling interval changing unit 36 sets the sampling interval according to the temperature signal (temperature Tw) sequentially input from the temperature sensor 22 or the opening signal (throttle opening TH) sequentially input from the throttle opening sensor 24. It can be changed. A specific method for changing the sampling interval will be described later.

  The ECU 26 (the CPU 28) includes an injector 38 that supplies fuel to the combustion chamber 14 of the internal combustion engine 12, an ignition plug 40 that performs ignition in the combustion chamber 14, and an exhaust gas that recirculates the exhaust gas from the exhaust pipe to the intake pipe. A reflux device 42 is connected. The CPU 28 is based on the negative pressure signal sequentially input from the negative pressure sensor 18, the crank signal sequentially input from the rotation angle sensor 20, and the in-cylinder pressure signal after sampling input from the sampling unit 34. The average effective pressure and pumping loss are calculated.

  In this case, the CPU 28 calculates the in-cylinder pressure increase rate DP based on the input crank signal and in-cylinder pressure signal, determines the occurrence of knocking or misfire based on the calculated in-cylinder pressure increase rate DP, and the determination result also In addition, the fuel supply start timing, the fuel supply amount, the ignition timing, and the exhaust gas recirculation amount are controlled. When the internal combustion engine 12 has a plurality of cylinders, the acupressure sensor 16, the injector 38, and the spark plug 40 are provided for each cylinder.

  Further, the ROM 30 stores a map of control amounts of the injector 38, the spark plug 40, and the exhaust gas recirculation device 42 corresponding to the calculation result of the CPU 28. The CPU 28 refers to these maps to determine control amounts for the injector 38, the spark plug 40, and the exhaust gas recirculation device 42. Further, the CPU 28 stores the calculation result and the like in the RAM 32.

  As shown in FIG. 2, the acupressure sensor 16 is disposed in the combustion chamber 14 at a position spaced from the cam chamber 44 of the internal combustion engine 12 and close to the spark plug 40. That is, in FIG. 2, when the cam chamber 44 is provided on the left side of the internal combustion engine 12 and the intake valve 48 and the exhaust valve 50 are disposed above and below the paper surface with the center position 46 of the combustion chamber 14 interposed therebetween, The acupressure sensor 16 is mounted in a fan-shaped region 54 opposite to the point 52 where knocking occurs in the combustion chamber 14. This region 54 is a region opposite to the knocking point 52 across the center position 46 in the combustion chamber 14, and a region surrounded by the spark plug 40, the center position 46 and the exhaust valve 50. It is.

[Operation of Internal Combustion Engine Control Device 10]
Next, the operation of the internal combustion engine control device 10 will be described with reference to FIGS. 3 to 4B. In this description of the operation, it will be described with reference to FIGS. 1 and 2 as necessary.

  Here, the sampling operation of the in-cylinder pressure signal by the sampling unit 34 and the sampling interval changing operation by the sampling interval changing unit 36 will be described. The operation of the CPU 28 is substantially the same as the operation of the CPU in Patent Document 1, and thus detailed description of the operation is omitted.

  FIG. 3 is a flowchart for explaining the operation of the sampling unit 34 and the sampling interval changing unit 36. 4A is a graph showing the relationship between the crank angle CA and the in-cylinder pressure Pi, and FIG. 4B is a graph showing the relationship between the crank angle CA and the in-cylinder pressure increase rate DP.

  Prior to the description of the operation shown in FIG. 3, the relationship between the crank angle CA and the in-cylinder pressure Pi and the relationship between the crank angle CA and the in-cylinder pressure increase rate DP will be described.

  The ignition in the combustion chamber 14 by the spark plug 40 (see FIGS. 1 and 2) is normally performed at a crank angle CA (for example, CA = −10 °) just before the compression top dead center (compression TDC, CA = 0 °). Done in In this case, the in-cylinder pressure Pi increases with a change in the crank angle CA after ignition.

  Here, in the case of MBT (Minimum Advance for the Best Torque), which is the optimal ignition condition, as shown by a solid line in FIG. 4A, the in-cylinder pressure Pi increases after ignition, becomes maximum after the compression TDC elapses, and then It becomes a characteristic of a substantially parabola that decreases.

  On the other hand, in the case of premature combustion, as shown by the broken line, the in-cylinder pressure Pi increases rapidly with the change in the crank angle CA after ignition. As a result, knocking may occur in premature combustion. In the case of slow combustion, as indicated by the alternate long and short dash line, the in-cylinder pressure Pi gradually increases as the crank angle CA changes. As a result, misfire may occur in slow combustion.

  Further, the in-cylinder pressure increase rate DP, which is the rate of change of the in-cylinder pressure Pi with respect to the crank angle CA, becomes positive or negative as the crank angle CA changes within the range of the crank angle CA in the vicinity of the compression TDC, as shown in FIG. 4B. Fluctuates in value. In this case, the in-cylinder pressure increase rate DP at MBT indicated by the solid line increases after ignition, and reaches a positive maximum value after the compression TDC has elapsed. Thereafter, the cylinder pressure increase rate DP decreases, reaches a negative maximum value, and then converges to DP = 0.

  On the other hand, in the case of premature combustion, as shown by the broken line, the in-cylinder pressure increase rate DP rapidly changes to a positive / negative value with respect to the change in the crank angle CA. In the case of slow combustion, as indicated by the alternate long and short dash line, the in-cylinder pressure increase rate DP has a small fluctuation range of positive and negative values with respect to the change in the crank angle CA.

  FIG. 4B shows, as an example, a change in the cylinder pressure increase rate DP when the sampling unit 34 samples the cylinder pressure signal at a sampling interval of 10 °. In this case, the cylinder pressure increase rate DP is obtained by dividing the difference between the cylinder pressure Pi indicated by the cylinder pressure signal sampled this time and the cylinder pressure Pi indicated by the cylinder pressure signal sampled last time by the sampling interval (10 °). (DP = {(current in-cylinder pressure Pi) − (previous in-cylinder pressure Pi)} / 10 °).

  Therefore, the CPU 28 compares the measured value of the in-cylinder pressure Pi and the calculated value of the in-cylinder pressure increase rate DP with the normal value (value at MBT) in the region of the crank angle CA in the vicinity of the compressed TDC after ignition. Thus, it is possible to determine whether the combustion state is normal or whether the abnormality of the internal combustion engine 12 such as knocking or misfire has occurred.

  Specifically, as shown in FIG. 4B, for example, at the crank angle CA = 0 ° of the compression TDC, the value of the in-cylinder pressure increase rate DP differs significantly between MBT, premature combustion, and slow combustion. . Accordingly, the normal value range (pressure change rate range) of the in-cylinder pressure increase rate DP at CA = 0 ° is set to a range between the allowable upper limit value AH and the allowable lower limit value AL, and the in-cylinder pressure increase rate DP is within the pressure change rate range. If it is within the range, it is determined that the combustion state of the internal combustion engine 12 is normal. On the other hand, if it is out of the pressure change rate range, it is possible to determine that the combustion state of the internal combustion engine 12 is abnormal. Therefore, the CPU 28 can appropriately control the internal combustion engine 12 based on such a determination result to set a normal combustion state.

  For this purpose, the sampling interval of the sampling unit 34 is shortened within a predetermined crank angle CA range near the compression TDC where an abnormality of the internal combustion engine 12 is expected to occur, and the accuracy of the determination process for the abnormality of the internal combustion engine 12 is increased. There is a need to improve. The sampling interval changing unit 36 performs such a sampling interval changing process.

  The flowchart of FIG. 3 is a flowchart for explaining operations of the sampling unit 34 and the sampling interval changing unit 36 based on such a viewpoint. This flowchart is executed at every sampling interval set by the sampling interval changing unit 36.

  First, in step S1, the sampling unit 34 samples the in-cylinder pressure signal input from the acupressure sensor 16 at the currently set sampling interval. For example, if the sampling interval is 30 °, the sampling unit 34 reads (captures) the in-cylinder pressure signal from the finger pressure sensor 16 at a crank angle CA of every 30 °. The sampling unit 34 outputs the sampled in-cylinder pressure signal to the CPU 28. On the other hand, the sampling interval changing unit 36 takes in the crank signal from the rotation angle sensor 20, the temperature signal from the temperature sensor 22, and the throttle opening signal from the throttle opening sensor 24 in addition to the in-cylinder pressure signal.

  In the next step S2, the sampling interval changing unit 36 determines that the crank angle CA indicated by the crank signal is within a predetermined crank angle CA including the crank angle (CA = 0 °) at the compression TDC, for example, −30 °. It is determined whether it is within the range of ≦ CA ≦ + 30 °. That is, ignition is performed within a range of −30 ° to + 30 °, and an abnormality of the internal combustion engine 12 such as knocking or misfire is expected to occur.

  In step S2, when the crank angle CA is outside the range of −30 ° to + 30 ° (CA <−30 ° or CA> + 30 °, step S2: NO), the sampling interval changing unit 36 performs the next step S3. The sampling interval until the next sampling processing is determined to be 30 °, the current sampling interval is changed to the determined sampling interval, and the current processing is terminated. Thus, the next sampling process (step S1) is executed at the timing when + 30 ° has elapsed from the current crank angle CA.

  On the other hand, when the crank angle CA is in the range of −30 ° to + 30 ° in step S2 (−30 ° ≦ CA ≦ + 30 °, step S2: YES), the sampling interval changing unit 36 performs the next step S4. Whether the temperature Tw of the internal combustion engine 12 indicated by the temperature signal exceeds a predetermined temperature threshold Twth, or whether the throttle opening TH indicated by the throttle opening signal exceeds a predetermined throttle opening threshold THth , Is determined. That is, the ignition conditions differ depending on the temperature Tw or the throttle opening TH, and the in-cylinder pressure Pi and the in-cylinder pressure increase rate DP change. Specifically, when the temperature Tw is high or the throttle opening TH is large, the internal combustion engine 12 is in a high load state, and knocking or misfire may occur.

  Here, when the temperature Tw is equal to or lower than the temperature threshold Twth (Tw ≦ Twth) and when the throttle opening TH is equal to or lower than the throttle opening threshold THth (TH ≦ THth) (step S4: NO), the sampling interval is changed. The unit 36 determines that there is no possibility of abnormality of the internal combustion engine 12 at the current temperature Tw or the throttle opening TH, and determines the sampling interval until the next sampling processing to 10 ° in the next step S5. The current sampling interval is changed to the determined sampling interval.

  In the next step S6, the sampling interval changing unit 36 determines whether or not the in-cylinder pressure increase rate DP is out of the predetermined pressure change rate range, that is, whether DP> AH or DP <AL. To do.

  In this case, when DP> AH is not satisfied and DP <AL is not satisfied (AL ≦ DP ≦ AH, step S6: NO), the sampling interval changing unit 36 determines that the internal combustion engine 12 is in a normal combustion state. The sampling interval determined in step S5 is confirmed, and the current process is terminated. Thus, the next sampling process (step S1) is executed at the timing when + 10 ° has elapsed from the current crank angle CA.

  On the other hand, when the determination result is affirmative in step S4 (Tw> Twth or TH> THth, step S4: YES), or when the determination result is positive in step S6 (DP> AH or DP < AL), the sampling interval changing unit 36 determines that there is a possibility that an abnormality of the internal combustion engine 12 such as knocking or misfire occurs, and in the next step S7, determines the sampling interval until the next sampling processing to 1 °. Then, after changing the current sampling interval to the determined sampling interval, the current processing is terminated. Thus, the next sampling process (step S1) is executed at the timing when + 1 ° has elapsed from the current crank angle CA.

  By repeatedly executing the processing of FIG. 3 at every sampling interval, the sampling unit has a relatively long sampling interval of 30 ° in the range of CA <−30 ° and + 30 ° <CA shown in FIGS. 4A and 4B. 34 performs a sampling process for the in-cylinder pressure signal. In the normal combustion state within the range of −30 ° ≦ CA ≦ + 30 °, the sampling unit 34 performs sampling processing on the in-cylinder pressure signal at a relatively short sampling interval of 10 °. Furthermore, within the range of −30 ° ≦ CA ≦ + 30 °, after ignition or after compression TDC, when there is a possibility that abnormality of the internal combustion engine 12 such as knocking or misfire may occur, a shorter 1 ° The sampling unit 34 performs sampling processing on the in-cylinder pressure signal at the sampling interval.

  As described above, the sampling unit 34 outputs the sampled in-cylinder pressure signal to the CPU 28. Therefore, the CPU 28 can accurately perform the determination process for the abnormality of the internal combustion engine 12 such as knocking or misfire based on the sequentially sampled in-cylinder pressure signal and the like. In particular, when there is a possibility that an abnormality of the internal combustion engine 12 may occur, the CPU 28 determines whether there is an abnormality in the internal combustion engine 12 based on a high-resolution in-cylinder pressure signal sampled at a sampling interval of 1 °, and The internal combustion engine 12 can be accurately controlled using the determination result.

[Effect of Internal Combustion Engine Control Device 10]
As described above, according to the internal combustion engine control apparatus 10 according to the present embodiment, only when there is an abnormality in which the in-cylinder pressure increase rate DP is outside the predetermined pressure change rate range (the range of AL ≦ DP ≦ AH shown in FIG. 4B) The sampling interval changing unit 36 shortens the sampling interval for the cylinder pressure signal in the sampling unit 34 (10 ° → 1 °). Thereby, it is possible to reduce the processing load for the determination processing based on the in-cylinder pressure signal after sampling and the control of the internal combustion engine 12 in the ECU 26 including the CPU 28.

  Further, when an abnormality of the internal combustion engine 12 such as knocking or misfire occurs, the in-cylinder pressure increase rate DP may be out of the pressure change rate range of AH to AL. In such a case, the determination accuracy for the abnormality of the internal combustion engine 12 in the CPU 28 can be increased by shortening the sampling interval and finely sampling the in-cylinder pressure signal by the sampling unit 34. Therefore, in the internal combustion engine control apparatus 10, it is possible to further reduce the processing load for the control of the internal combustion engine 12 while maintaining the determination accuracy for the abnormality of the internal combustion engine 12 as compared with the technique of Patent Document 1.

  Further, by limiting the range of the crank angle CA that shortens the sampling interval after ignition, the determination accuracy for the abnormality of the internal combustion engine 12 can be improved.

  Further, at the crank angle CA in the vicinity of the compression TDC, the in-cylinder pressure increase rate DP tends to deviate from the pressure change rate range due to the occurrence of an abnormality in the internal combustion engine 12 such as knocking or misfire. Therefore, by setting the range of the crank angle CA for shortening the sampling interval so as to include the crank angle CA = 0 ° in the compression TDC, it is possible to further improve the determination accuracy for the abnormality of the internal combustion engine 12.

  The sampling interval changing unit 36 may calculate the rotational speed of the internal combustion engine 12 based on the crank angle CA and adjust the pressure change rate range (AL to AH) according to the calculated rotational speed. In other words, the cylinder pressure increase rate DP changes depending on the rotational speed and load state of the internal combustion engine 12, and therefore, by setting an appropriate pressure change rate range according to the rotational speed, the determination accuracy for abnormality of the internal combustion engine 12 is further increased. Can be improved. In order to enable such adjustment, the sampling interval changing unit 36 has a table or map indicating the relationship between the rotational speed and the load state and the pressure change rate range, and the rotational speed is referenced with reference to this table or map. In addition, an appropriate pressure change rate range (allowable upper limit value AH, allowable lower limit value AL) corresponding to the load state may be set.

  Furthermore, by changing the sampling interval to 10 ° or less, for example, 1 °, sufficient determination accuracy can be ensured for an abnormality in the internal combustion engine 12.

  Furthermore, when Tw> Twth or TH> THth, the determination accuracy for the abnormality of the internal combustion engine 12 can be improved by shortening the sampling interval.

  Further, since the finger pressure sensor 16 is disposed in the combustion chamber 14 at a position separated from the cam chamber 44 of the internal combustion engine 12 and close to the spark plug 40, noise with respect to the in-cylinder pressure Pi detected by the finger pressure sensor 16 is detected. The influence of can be reduced. That is, there is a high probability that knocking occurs at the point 52 on the cam chamber 44 side where the temperature drop due to the outside air is small (where the pressure due to ignition of the spark plug 40 propagates with a delay). In this case, the pressure propagated by knocking from the point 52 increases as the distance from the point 52 increases, and is less susceptible to noise. Therefore, if the acupressure sensor 16 is disposed in the vicinity of the spark plug 40 away from the point 52, the in-cylinder pressure Pi can be suitably detected.

  In the above description, the case where the finger pressure sensor 16 is disposed in the combustion chamber 14 has been described. The internal combustion engine control device 10 only needs to be able to detect the in-cylinder pressure Pi, so that the in-cylinder pressure sensor may be disposed in the combustion chamber 14 instead of the finger pressure sensor 16. Even in this case, the above effects can be easily obtained.

  As mentioned above, although this invention was demonstrated using suitable embodiment, the technical scope of this invention is not limited to the description range of said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. It is apparent from the description of the scope of claims that the embodiments added with such changes or improvements can also be included in the technical scope of the present invention. In addition, the reference numerals in parentheses described in the claims are appended to the reference numerals in the accompanying drawings for easy understanding of the present invention. It should not be construed as limited.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine control apparatus 12 ... Internal combustion engine 14 ... Combustion chamber 16 ... Finger pressure sensor 18 ... Negative pressure sensor 20 ... Rotation angle sensor 22 ... Temperature sensor 24 ... Throttle opening sensor 26 ... ECU 28 ... CPU
30 ... ROM 32 ... RAM
34 ... Sampling section 36 ... Sampling interval changing section 38 ... Injector 40 ... Spark plug 42 ... Exhaust gas recirculation device 44 ... Cam chamber 46 ... Center position 48 ... Intake valve 50 ... Exhaust valve 52 ... Point 54 ... Area

Claims (8)

A pressure sensor (16) for detecting the pressure (Pi) in the combustion chamber (14) of the internal combustion engine (12), and sampling for sampling a pressure signal corresponding to the pressure (Pi) detected by the pressure sensor (16). An internal combustion engine control device (10) having a section (34) and a control section (26) for controlling the internal combustion engine (12) based on the sampled pressure signal;
A rotation angle sensor (20) for detecting a rotation angle (CA) of the internal combustion engine (12);
Based on the pressure (Pi) and the rotation angle (CA), a pressure change rate (DP) of the pressure (Pi) with respect to the rotation angle (CA) is calculated, and the pressure change calculated in a predetermined rotation angle range is calculated. A sampling interval changing unit (36) for shortening a sampling interval for the pressure signal in the sampling unit (34) when the rate (DP) is out of a predetermined pressure change rate range;
The internal combustion engine control device (10), further comprising: The internal combustion engine controller (10) according to claim 1,
The internal combustion engine control device (10), wherein the rotational angle range is a range of a rotational angle (CA) after ignition of the internal combustion engine (12). The internal combustion engine control device (10) according to claim 1 or 2,
The internal combustion engine control device (10), wherein the rotational angle range is a range including a rotational angle (CA) at a top dead center of the internal combustion engine (12). In the internal combustion engine control device (10) according to any one of claims 1 to 3,
The sampling interval changing unit (36) calculates the rotation speed of the internal combustion engine (12) based on the rotation angle (CA), and adjusts the pressure change rate range according to the calculated rotation speed. An internal combustion engine control device (10) characterized. In the internal combustion engine control device (10) according to any one of claims 1 to 4,
The sampling interval changing unit (36) changes the sampling interval to 10 ° or less when the pressure change rate (DP) is out of the pressure change rate range. . In the internal combustion engine control device (10) according to any one of claims 1 to 5,
A temperature sensor (22) for detecting the temperature (Tw) of the internal combustion engine (12);
The internal combustion engine control device (10), wherein the sampling interval changing unit (36) shortens the sampling interval when the temperature (Tw) exceeds a predetermined temperature threshold (Twth). In the internal combustion engine control device (10) according to any one of claims 1 to 6,
A throttle opening sensor (24) for detecting a throttle opening (TH) of the internal combustion engine (12);
The sampling interval changing unit (36) shortens the sampling interval when the throttle opening (TH) exceeds a predetermined throttle opening threshold (THth). ). In the internal combustion engine control device (10) according to any one of claims 1 to 7,
The pressure sensor (16) is disposed in the combustion chamber (14) at a position separated from the cam chamber (44) of the internal combustion engine (12) and close to the spark plug (40). An internal combustion engine control device (10) characterized.

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