JP2013015105A - Knock determination apparatus for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a fuel injection timing to proper timing according to various requests, while improving engine knock detection accuracy.SOLUTION: Vibration strength (for example, a peak hold value or the like of an output signal of a knock sensor 27) during a predetermined knock determination period is calculated and vibration strength in a fuel injection valve noise period (a period including noise due to operation of a fuel injection valve 21) is calculated. Thereafter, on the basis of larger vibration strength of the vibration strength in the knock determination period and the vibration strength in the fuel injection valve noise period, a knock determination value is calculated to perform knock determination. Thereby, it is possible to prevent error determination that determines a state where vibration strength is increased by fuel injection valve noise (noise due to operation of the fuel injection valve 21) as occurrence of a knock, and the fuel injection timing can be set to proper timing according to various requests since the fuel injection timing is not required to be changed according to the knock determination period.

Description

  The present invention relates to a knock determination device for an internal combustion engine that determines the presence or absence of knock based on an output signal of a knock sensor that detects knock vibration of the internal combustion engine.

  In a system for determining the presence or absence of a knock based on an output signal of a knock sensor during a predetermined knock determination period, as a technique for preventing a decrease in knock detection accuracy due to the influence of noise generated by the operation of a fuel injection valve, for example, As described in JP-A-2004-251218, the fuel injection timing is set according to the knock determination period so that the noise generation period due to the operation of the fuel injection valve does not overlap with the knock determination period. There is something to do.

  Further, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2009-257121), at least one of noise due to closing of the intake valve and exhaust valve and noise due to operation of the fuel injection valve is knocked. In some cases, the variable valve mechanism and the fuel injection valve are controlled so as to be superimposed on the output signal of the knock sensor during the determination period.

JP 2004-251218 A JP 2009-257121 A

  However, in the technique of Patent Document 1, in order to improve the knock detection accuracy, the fuel injection timing is changed so that the noise generation period due to the operation of the fuel injection valve does not overlap with the knock determination period. There is a drawback in that it cannot be set at an appropriate time according to various requirements other than improvement in detection accuracy (for example, fuel saving, exhaust emission reduction, oil dilution prevention, etc.).

  Further, in the technique disclosed in Patent Document 2, in order to improve knock detection accuracy, noise due to closing of the intake valve and exhaust valve and noise due to operation of the fuel injection valve are superimposed on the output signal of the knock sensor during the knock determination period. As described above, the valve timing and fuel injection timing are changed by controlling the variable valve mechanism and the fuel injection valve, so that the valve timing and fuel injection timing cannot be set to the appropriate timing according to various requirements other than the improvement of knock detection accuracy. There is.

  Accordingly, the problem to be solved by the present invention is to provide a knock determination device for an internal combustion engine that can set the fuel injection timing or the valve timing to an appropriate timing according to various requirements while improving knock detection accuracy. It is in.

  In order to solve the above-described problem, the invention according to claim 1 calculates a vibration intensity based on an output signal of a knock sensor that detects knock vibration of an internal combustion engine, compares the vibration intensity with a knock determination value, and knocks In the knock determination device of the internal combustion engine provided with the knock determination means for determining the presence or absence of the engine, the knock determination means calculates the vibration intensity in a predetermined knock determination period and includes a period including noise due to the operation of the fuel injection valve (hereinafter, “ The vibration intensity in the "injection valve noise period" is calculated, and the knock determination value is calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period. is there.

  In this configuration, since the knock determination value can be calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period, the knock determination can be performed. A state in which the vibration intensity is increased due to noise caused by the operation of the injection valve can be prevented from being erroneously determined as knock occurrence (with knock), and knock detection accuracy can be improved. In addition, since it is not necessary to change the fuel injection timing according to the knock determination period, the fuel injection timing can be set to an appropriate time according to various demands (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.). it can.

  In addition, in a system that always calculates the knock determination value based on the vibration intensity in the knock determination period, the knock determination is performed when the injection valve noise enters the knock determination period or exits from the knock determination period due to a change in the fuel injection timing. Although the knock detection accuracy may decrease until the value stabilizes, the present invention determines whether or not the knock determination period and the injection valve noise period overlap (that is, the injection valve noise enters the knock determination period). The knock determination value can be set based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period regardless of whether the fuel injection timing is changed. Even when the injection valve noise enters or exits the knock determination period, the knock determination value is maintained at an appropriate level. Bets can be, it is possible to ensure the knock detection accuracy during transients.

  In general, the injection valve noise (noise due to the operation of the fuel injection valve) includes the valve opening noise generated by the valve opening operation of the fuel injection valve (for example, the seating of the valve body when the valve is opened), and the valve closing operation of the fuel injection valve. Although there is valve closing noise that occurs due to (for example, the seating of the valve body when the valve is closed), the valve opening noise tends to have a greater vibration intensity than the valve closing noise.

  Therefore, as in claim 2, the injection valve noise period is a period including at least the valve opening noise among the valve opening noise generated by the valve opening operation of the fuel injection valve and the valve closing noise generated by the valve closing operation (that is, It is preferable to set a period including both valve opening noise and valve closing noise or a period including only valve opening noise. In this way, it is possible to set a knock determination value in consideration of the vibration intensity of the valve opening noise whose vibration intensity is larger than the valve closing noise of the fuel injector, and the vibration intensity increases due to the valve opening noise of the fuel injector. It is possible to prevent erroneous determination of a knocked state as a knock occurrence.

  Furthermore, as in claim 3, when the vibration intensity during the injection valve noise period is calculated during the execution of the divided injection in which the fuel is divided into a plurality of times, any of the plurality of divided injections is performed. Alternatively, the vibration intensity during the injection valve noise period of one injection may be calculated. In this way, it is possible to easily calculate the vibration intensity during the injection valve noise period even during the execution of divided injection.

  According to another aspect of the present invention, the knock intensity is calculated based on an output signal of a knock sensor that detects knock vibration of the internal combustion engine, and the presence or absence of knock is determined by comparing the vibration intensity with a knock determination value. In the knock determination device for an internal combustion engine provided with the means, the knock determination means learns the vibration intensity of noise (hereinafter referred to as “injection valve noise”) due to the operation of the fuel injection valve when there is no knock, and the injection valve noise The knock determination value may be calculated based on the learned value of the vibration intensity.

  Even in this case, it is possible to prevent erroneous determination that the vibration intensity is increased due to the injection valve noise (noise due to the operation of the fuel injection valve) as knocking (with knocking), and to improve knock detection accuracy. In addition, since it is not necessary to change the fuel injection timing according to the knock determination period, the fuel injection timing should be set to an appropriate time according to various requirements (for example, fuel economy, exhaust emission reduction, oil dilution prevention, etc.) Can do. Further, since the knock determination value can be set based on the learned value of the vibration intensity of the injection valve noise regardless of whether or not the injection valve noise enters the knock determination period, the injection valve can be changed by changing the fuel injection timing. Even when the noise enters the knock determination period or comes out of the knock determination period, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  In this case, as described in claim 5, it is preferable to learn the vibration intensity of the injection valve noise when it is determined that there is no knock in the operation region or frequency band where the influence of the injection valve noise on the output signal of the knock sensor is large. By doing this, there is no knocking in the operating region and frequency band where the influence of the injection valve noise on the output signal of the knock sensor is large (that is, the operating region and frequency band where the vibration intensity of the injection valve noise is greater than the background level). At this time, the vibration intensity of the injection valve noise can be learned with high accuracy.

  Further, as described in claim 6, when knock determination is performed in an operating region or frequency band where the influence of the injection valve noise on the output signal of the knock sensor is large, the knock calculated based on the learning value of the vibration intensity of the injection valve noise A determination value may be used. In this way, knock determination is performed in an operation region or frequency band where the influence of the injection valve noise is large on the output signal of the knock sensor (that is, an operation region or frequency band where the vibration intensity of the injection valve noise is greater than the background level). In this case, it can be reliably prevented that the state in which the vibration intensity is increased due to the injection valve noise is erroneously determined as knocking.

  According to another aspect of the present invention, the knock intensity is calculated based on an output signal of a knock sensor that detects knock vibration of the internal combustion engine, and the presence / absence of knock is determined by comparing the vibration intensity with a knock determination value. In the knock determination device for an internal combustion engine provided with the means, the knock determination means calculates a vibration intensity in a predetermined knock determination period and includes a period including noise due to the operation of the intake valve and / or the exhaust valve (hereinafter referred to as “valve valve system”). The vibration determination value in the “noise period” may be calculated, and the knock determination value may be calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the valve train noise period.

  In this configuration, since the knock determination value can be calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the valve noise period, the valve determination noise can be determined. A state in which the vibration intensity is increased due to (noise due to the operation of the intake valve or the exhaust valve) can be prevented from being erroneously determined as knock occurrence (with knock), and knock detection accuracy can be improved. In addition, since it is not necessary to change the valve timing according to the knock determination period, the valve timing can be set to an appropriate time according to various requirements (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.).

  In addition, in a system that always calculates the knock determination value based on the vibration intensity during the knock determination period, the knock determination is performed when valve system noise enters the knock determination period or exits from the knock determination period due to a change in valve timing. Although the knock detection accuracy may decrease until the value becomes stable, the present invention determines whether or not the knock determination period and the valve operating noise period overlap (that is, the valve operating noise is the knock determination period). The knock determination value can be set based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the valve train noise period regardless of whether or not Even when the valve system noise enters or exits the knock determination period due to changes in the Can be lifting, it is possible to ensure the knock detection accuracy during transients.

  In general, the intake valve and the exhaust valve tend to increase the vibration intensity of the valve closing noise generated by the valve closing operation (for example, the seating of the valve when the valve is closed). Therefore, as in claim 8, the valve operating noise period may be set to a period including valve closing noise generated by the valve closing operation of the intake valve and / or the exhaust valve. In this way, it is possible to set a knock determination value that takes into account the vibration intensity of the closing noise of the intake valve or exhaust valve, and knock the state where the vibration intensity has increased due to the closing noise of the intake valve or exhaust valve. It is possible to prevent erroneous determination as occurrence.

  According to another aspect of the present invention, the knock intensity is calculated based on an output signal of a knock sensor that detects knock vibration of the internal combustion engine, and the presence or absence of knock is determined by comparing the vibration intensity with a knock determination value. In the knock determination device for an internal combustion engine provided with the means, the knock determination means learns the vibration intensity of noise (hereinafter referred to as “valve system noise”) due to the operation of the intake valve and / or the exhaust valve when there is no knock. The knock determination value may be calculated based on the learned value of the vibration intensity of the valve operating noise.

  Even in this case, it is possible to prevent erroneous determination of knocking (with knocking) as the vibration intensity increases due to valve operating noise (noise due to intake valve or exhaust valve operation), improving knock detection accuracy. Since the valve timing does not need to be changed according to the knock determination period, the valve timing is set to an appropriate time according to various demands (for example, fuel economy, exhaust emission reduction, oil dilution prevention, etc.) be able to. In addition, the knock determination value can be set based on the learned value of the vibration intensity of the valve operating noise regardless of whether or not the valve operating noise has entered the knock determination period. Even when the valve system noise enters or exits the knock determination period, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  In this case, as described in claim 10, when it is determined that there is no knock in an operation region or frequency band where the influence of the valve system noise on the output signal of the knock sensor is large, the vibration intensity of the valve system noise is learned. good. In this way, knocking is performed in an operation region or frequency band where the influence of valve system noise on the output signal of the knock sensor is large (that is, an operation region or frequency band where the vibration intensity of valve system noise is greater than the background level). The vibration intensity of the valve train noise can be learned with high accuracy in the absence state.

  Further, as described in claim 11, when knock determination is performed in an operation region or frequency band where the influence of valve operating noise on the output signal of the knock sensor is large, calculation is performed based on a learned value of the vibration intensity of valve operating noise. The knock determination value may be used. In this way, knocking is performed in an operation region or frequency band where the influence of valve system noise on the output signal of the knock sensor is large (that is, an operation region or frequency band where the vibration intensity of valve system noise is greater than the background level). When the determination is made, it is possible to reliably prevent a state in which the vibration intensity is increased due to the valve operating noise from being erroneously determined as knocking.

FIG. 1 is a diagram showing a schematic configuration of an engine control system in Embodiment 1 of the present invention. FIG. 2 is a flowchart showing the flow of processing of the knock determination routine of the first embodiment. FIG. 3 is a time chart showing an example of the knock determination period. FIG. 4 is a diagram showing the injection valve noise, the knock waveform, and the vibration intensity. FIG. 5 is a flowchart illustrating the processing flow of the knock determination routine according to the second embodiment. FIG. 6 is a flowchart illustrating the processing flow of the knock determination routine according to the third embodiment. FIG. 7 is a flowchart illustrating the processing flow of the knock determination routine according to the fourth embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and each cylinder of the engine 11 is provided with a fuel injection valve 21 that directly injects fuel into the cylinder. Yes. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of the ignition plug 22 of each cylinder.

  Further, the engine 11 is provided with an intake side variable valve timing device 32 that changes the valve timing (opening / closing timing) of the intake valve 30 and an exhaust side variable valve timing device 33 that changes the valve timing of the exhaust valve 31. It has been.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  Further, a cooling water temperature sensor 26 for detecting the cooling water temperature and a knock sensor 27 for detecting knock vibration are attached to the cylinder block of the engine 11. A crank angle sensor 29 that outputs a pulse signal every time the crankshaft 28 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 28, and the crank angle and the engine are determined based on the output signal of the crank angle sensor 29. The rotation speed is detected.

  Outputs of these various sensors are input to an electronic control unit (hereinafter referred to as “ECU”) 34. The ECU 34 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount and the ignition timing according to the engine operating state. The throttle opening (intake air amount) and the like are controlled.

  Further, the ECU 34 calculates the vibration intensity based on the output signal of the knock sensor 27 and compares the vibration intensity with the knock determination value to determine the presence or absence of knock. When it is determined that there is a knock, the ignition timing is corrected to the retard side to suppress the knock, and when it is determined that there is no knock, the ignition timing is corrected to the advance side to perform the ignition control. Is advanced to near the knock limit to improve engine output and fuel efficiency.

  At this time, in the first embodiment, the ECU 34 executes a knock determination routine of FIG. 2 described later, thereby performing the knock determination as follows.

  First, based on the output signal of the knock sensor 27, the vibration intensity in a predetermined knock determination period (see FIG. 3) is calculated, and a period including noise due to the operation of the fuel injection valve 21 (hereinafter referred to as “injection valve noise period”). ) Is calculated. In this case, for example, the peak hold value (maximum value) of the output signal of the knock sensor 27 is calculated as the vibration intensity. Alternatively, an integrated value (area) of the output signal of the knock sensor 27, a trajectory length, or the like may be calculated as the vibration intensity.

  Thereafter, the larger one of the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period is selected and logarithmically converted. The vibration intensity data after logarithmic transformation is statistically processed to determine the vibration intensity distribution, the median value VMED and the standard deviation SGM of this vibration intensity distribution are calculated, and the median value VMED is u times the standard deviation SGM ( For example, the knock determination value is obtained by adding three times the value.

Knock judgment value = VMED + u × SGM
Here, the u value is set to “3”, for example, but may be corrected based on the distribution state of the vibration intensity distribution, the required knock detection sensitivity, the engine operating state, and the like.

  After this, the vibration intensity after logarithmic conversion is compared with the knock determination value. If the vibration intensity after logarithmic conversion is larger than the knock determination value, it is determined that there is a knock, and the vibration intensity after logarithmic conversion is equal to or less than the knock determination value. In the case of, it is determined that there is no knock. Here, the vibration intensity after logarithmic conversion to be compared with the knock determination value may be logarithmically converted between the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period. Although it is good, you may make it use what carried out logarithmic conversion of the vibration intensity | strength in a knock determination period.

Next, a method for setting the injection valve noise period (period including noise due to the operation of the fuel injection valve 21) will be described.
As shown in FIG. 4, in general, the injection valve noise (noise due to the operation of the fuel injection valve 21) includes valve opening noise generated by the valve opening operation of the fuel injection valve 21 (for example, seating of the valve body when the valve is opened). Then, there is valve closing noise generated by the valve closing operation of the fuel injection valve 21 (for example, seating of the valve body at the time of valve closing), but the valve opening noise tends to have a greater vibration intensity than the valve closing noise. .

  Therefore, in the first embodiment, the injection valve noise period includes at least valve opening noise of the valve opening noise and valve closing noise of the fuel injection valve 21 (that is, includes both valve opening noise and valve closing noise). It is set to a predetermined period after the start of injection so that only valve noise is included. At that time, a delay time from when the injection start timing of the fuel injection valve 21 (ON timing of the injection signal) to when the valve element is seated and valve opening noise is generated, or the injection end timing of the fuel injection valve 21 (OFF of the injection signal) The injection valve noise period (a period that includes both valve opening noise and valve closing noise or a period that includes only valve opening noise) by considering the delay time from when the valve body is seated to when valve closing noise occurs. ) Can be set appropriately.

  Further, when the vibration intensity in the injection valve noise period is calculated during the execution of the divided injection in which the fuel is divided into a plurality of times, the injection of any one of the plurality of divided injections is performed. The vibration intensity in the valve noise period is calculated (for example, when the fuel is injected divided into two times, the vibration intensity in the injection valve noise period of the first or second injection is calculated). In this way, it is possible to easily calculate the vibration intensity during the injection valve noise period even during the execution of divided injection.

The knock determination of the first embodiment described above is executed by the ECU 34 according to the knock determination routine of FIG. The processing contents of this routine will be described below.
The knock determination routine shown in FIG. 2 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 34 (while the ignition switch is on), and serves as a knock determination means in the claims. When this routine is started, first, in step 101, the vibration intensity in the knock determination period (for example, the peak hold value of the output signal of the knock sensor 27) is calculated, and in step 102, the vibration intensity in the injection valve noise period. (For example, the peak hold value of the output signal of the knock sensor 27) is calculated. Here, the injection valve noise period is set to a period including both the valve opening noise and the valve closing noise of the fuel injection valve 21 or a period including only the valve opening noise.

  Thereafter, the process proceeds to step 103, and after selecting the larger vibration intensity between the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period, the process proceeds to step 104, and the selected vibration intensity (that is, in the knock determination period). The larger one of the vibration intensity and the vibration intensity during the injection valve noise period) is logarithmically converted.

Thereafter, the process proceeds to step 105, where the vibration intensity after logarithmic transformation is statistically processed to determine the vibration intensity distribution, the median value VMED and the standard deviation SGM of the vibration intensity distribution are calculated, and the standard deviation is calculated as the median value VMED. A knock determination value is obtained by adding u times (for example, 3 times) of SGM.
Knock judgment value = VMED + u × SGM

  Thereafter, the process proceeds to step 106, where it is determined whether or not the vibration intensity after logarithmic conversion is larger than the knock determination value. Here, the vibration intensity after logarithmic conversion to be compared with the knock determination value may be logarithmically converted between the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period. Although it is good, you may make it use what carried out logarithmic conversion of the vibration intensity | strength in a knock determination period.

  If it is determined in step 106 that the vibration intensity after logarithmic conversion is larger than the knock determination value, the process proceeds to step 107 and it is determined that there is a knock. On the other hand, if it is determined in step 106 that the vibration intensity after logarithmic conversion is equal to or less than the knock determination value, the process proceeds to step 108 and it is determined that there is no knock. When it is determined that there is a knock, the ECU 34 corrects the ignition timing to the retard side to suppress the knock, and when it is determined that there is no knock, the ECU 34 performs a knock control to correct the ignition timing to the advance side.

  In the first embodiment described above, since the knock determination value is calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the injection valve noise period, the knock determination is performed. A state in which the vibration intensity is increased by the injection valve noise (noise due to the operation of the fuel injection valve 21) can be prevented from being erroneously determined as knock occurrence (with knock), and the knock detection accuracy can be improved. In addition, since it is not necessary to change the fuel injection timing according to the knock determination period, the fuel injection timing can be set to an appropriate time according to various demands (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.). it can.

  Further, regardless of whether or not the knock determination period and the injection valve noise period overlap (that is, whether or not the injection valve noise enters the knock determination period), the vibration intensity and the injection valve noise period in the knock determination period Because the knock determination value can be set based on the larger vibration intensity of the vibration at, when the injection valve noise enters or exits the knock determination period due to changes in the fuel injection timing However, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  Further, in the first embodiment, the injection valve noise period is set to a period including at least the valve opening noise of the fuel injection valve 21 (that is, a period including both the valve opening noise and the valve closing noise or a period including only the valve opening noise). Since it is set, it is possible to set a knock determination value in consideration of the vibration intensity of the valve opening noise whose vibration intensity is larger than the valve closing noise of the fuel injection valve 21, and vibrate due to the valve opening noise of the fuel injection valve 21. It is possible to prevent a state in which the strength is increased from being erroneously determined as the occurrence of knocking.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the ECU 34 executes a knock determination routine shown in FIG. 5 to be described later, so that the operation region where the influence of the injection valve noise on the output signal of the knock sensor 27 is large (that is, the vibration intensity of the injection valve noise is at the background level). The vibration intensity of the injection valve noise is learned when it is determined that there is no knocking in the operation region where the injection valve noise is larger), and knocking is performed in the operation region where the influence of the injection valve noise on the output signal of the knock sensor 27 is large. When making the determination, the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the injection valve noise.

  In the knock determination routine of FIG. 5, first, in step 201, after calculating the vibration intensity (for example, the peak hold value of the output signal of the knock sensor 27) in the knock determination period, the process proceeds to step 202 and the output signal of the knock sensor 27 is calculated. It is determined whether or not it is an operation region in which the influence of the injection valve noise is large (that is, an operation region in which the vibration intensity of the injection valve noise is greater than the background level). It is determined by whether or not.

  If it is determined in this step 202 that the operation region has a large influence of the injection valve noise on the output signal of the knock sensor 27 (that is, the operation region in which the vibration intensity of the injection valve noise is greater than the background level), Proceeding to step 203, after reading a learned value of the vibration intensity of the injection valve noise learned by the method described later, the process proceeds to step 204, and a value obtained by multiplying the learned value of the vibration intensity of the injection valve noise by u (for example, three times). Calculated as a knock determination value. Here, the u value is set to “3”, for example, but may be corrected based on the distribution state of the vibration intensity distribution, the required knock detection sensitivity, the engine operating state, and the like.

  Thereafter, the process proceeds to step 205, where it is determined whether or not the vibration intensity in the knock determination period is greater than the knock determination value. If it is determined that the vibration intensity is greater than the knock determination value, the process proceeds to step 206. It is determined that there is a knock.

  On the other hand, if it is determined in step 205 that the vibration intensity is equal to or less than the knock determination value, the process proceeds to step 207, and after determining that there is no knock, the process proceeds to step 208, where the vibration intensity of the injection valve noise is determined as follows. To learn. A process for calculating the vibration intensity (for example, the peak hold value of the output signal of the knock sensor 27) in a predetermined period (for example, the injection valve noise period) is repeated a predetermined number of times or a predetermined cycle to statistically process the vibration intensity data. The vibration intensity distribution is determined, and the value of a predetermined percentage point (for example, 97% point) of the vibration intensity distribution is learned as the vibration intensity of the injection valve noise. The learned value of the vibration intensity of the injection valve noise is stored in a rewritable nonvolatile memory (a rewritable memory that holds stored data even when the ECU 34 is powered off) such as a backup RAM (not shown) of the ECU 34.

  On the other hand, if it is determined in step 202 that the operating region is not affected by the injection valve noise greatly on the output signal of the knock sensor 27, the routine proceeds to step 209, where normal knock determination is performed. In this normal knock determination, it is determined whether or not the vibration intensity in the knock determination period is larger than the normal knock determination value. If it is determined that the vibration intensity is larger than the knock determination value, it is determined that there is a knock. When it is determined that the vibration intensity is equal to or less than the knock determination value, it is determined that there is no knock.

  In the second embodiment described above, the vibration intensity of the injection valve noise is learned when there is no knock, and the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the injection valve noise. As a result, it is possible to prevent the occurrence of knocking (with knock) from erroneously determining that the vibration intensity has increased due to injection valve noise, improving knock detection accuracy, and setting the fuel injection timing to the knock determination period. Therefore, the fuel injection timing can be set to an appropriate time according to various demands (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.). Further, since the knock determination value can be set based on the learned value of the vibration intensity of the injection valve noise regardless of whether or not the injection valve noise enters the knock determination period, the injection valve can be changed by changing the fuel injection timing. Even when the noise enters the knock determination period or comes out of the knock determination period, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  Further, in the second embodiment, when it is determined that there is no knock in the operation region where the influence of the injection valve noise on the output signal of the knock sensor 27 is large (that is, the operation region where the vibration intensity of the injection valve noise is greater than the background level). Since the vibration intensity of the injection valve noise is learned (when there is no knock), the vibration intensity of the injection valve noise can be learned with high accuracy.

  Further, in the second embodiment, when the knock determination is performed in the operation region where the influence of the injection valve noise on the output signal of the knock sensor 27 is large (that is, the operation region where the vibration intensity of the injection valve noise is larger than the background level). Since the knock determination is performed using the knock determination value calculated based on the learning value of the vibration intensity of the injection valve noise, the state where the vibration intensity is increased due to the injection valve noise is erroneously determined as knock occurrence. It can be surely prevented.

  In the second embodiment, the vibration intensity of the injection valve noise is learned when it is determined that there is no knock in the operation region where the influence of the injection valve noise on the output signal of the knock sensor 27 is large, and the injection with respect to the output signal of the knock sensor 27 is performed. When knock determination is performed in an operation region where the influence of valve noise is large, knock determination is performed using the knock determination value calculated based on the learning value of the vibration intensity of the injection valve noise, but is not limited thereto, When it is determined that there is no knock in a frequency band (for example, 10 to 20 kHz) where the influence of the injection valve noise on the output signal of the knock sensor 27 is large, the vibration intensity of the injection valve noise is learned, and the injection valve noise on the output signal of the knock sensor 27 The knock determination value calculated based on the learned value of the vibration intensity of the injection valve noise when knock determination is performed in the frequency band where the influence of There may also be to perform the knock determination.

  Further, the knock determination value calculated based on the learning value of the vibration intensity of the injection valve noise is used regardless of whether or not the operation region or frequency band is greatly affected by the injection valve noise on the output signal of the knock sensor 27. You may make it perform knock determination.

  Further, in each of the first and second embodiments, the knock determination value is calculated based on the vibration intensity of the valve opening noise or the valve closing noise of the fuel injection valve 21. However, the present invention is not limited to this. When noise having a greater vibration intensity than valve opening noise or valve closing noise is generated by the operation, the knock determination value may be calculated based on the vibration intensity of the noise.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the third embodiment, the ECU 34 executes a knock determination routine of FIG. 6 to be described later, thereby calculating the vibration intensity in a predetermined knock determination period and a period including noise due to the operation of the intake valve 30 and the exhaust valve 31 ( (Hereinafter referred to as “valve system noise period”), and the knock determination value is calculated based on the larger one of the vibration intensity in the knock determination period and the vibration intensity in the valve noise period. Knock determination is performed.

  In general, the intake valve 30 and the exhaust valve 31 tend to increase the vibration intensity of the valve closing noise generated by the valve closing operation (for example, the seating of the valve when the valve is closed). The noise period is set to both a period including the valve closing noise of the intake valve 30 and a period including the valve closing noise of the exhaust valve 31. If the valve closing noise of the intake valve 30 has a greater influence on the knock determination than the valve closing noise of the exhaust valve 31, the valve operating noise period is limited to a period including the valve closing noise of the intake valve 30 only. You may make it set. On the other hand, when the valve closing noise of the exhaust valve 31 has a greater influence on the knock determination than the valve closing noise of the intake valve 30, the valve operating noise period is set to only the period including the valve closing noise of the exhaust valve 31. You may make it set.

  In the knock determination routine of FIG. 6, first, in step 301, the vibration intensity in the knock determination period (for example, the peak hold value of the output signal of the knock sensor 27) is calculated, and in step 302, the vibration in the valve train noise period. The intensity (for example, the peak hold value of the output signal of the knock sensor 27) is calculated. Here, the valve operating noise period is set to one or both of a period including the valve closing noise of the intake valve 30 and a period including the valve closing noise of the exhaust valve 31.

  Thereafter, the process proceeds to step 303, and after selecting the larger vibration intensity between the vibration intensity in the knock determination period and the vibration intensity in the valve train noise period, the process proceeds to step 304 and the selected vibration intensity (that is, the knock determination period). Logarithm conversion is performed on the larger vibration intensity of the vibration intensity in the valve system noise period and the vibration intensity in the valve system noise period.

Thereafter, the process proceeds to step 305, the vibration intensity after logarithmic transformation is statistically processed to determine the vibration intensity distribution, the median value VMED and the standard deviation SGM of the vibration intensity distribution are calculated, and the standard deviation is calculated as the median value VMED. A knock determination value is obtained by adding u times (for example, 3 times) of SGM.
Knock judgment value = VMED + u × SGM

  Thereafter, the process proceeds to step 306, where it is determined whether the vibration intensity after logarithmic conversion is larger than the knock determination value. Here, the vibration intensity after logarithmic conversion to be compared with the knock determination value is obtained by logarithmically converting the vibration intensity in the knock determination period and the vibration intensity in the valve train noise period, whichever is larger. Alternatively, a logarithmically converted vibration intensity in the knock determination period may be used.

  If it is determined in step 306 that the vibration intensity after logarithmic conversion is larger than the knock determination value, the process proceeds to step 307 and it is determined that there is a knock. On the other hand, if it is determined in step 306 that the vibration intensity after logarithmic conversion is equal to or smaller than the knock determination value, the process proceeds to step 308 and it is determined that there is no knock.

  In the third embodiment described above, the knock determination value is calculated based on the larger vibration intensity of the vibration intensity in the knock determination period and the vibration intensity in the valve train noise period, so that the knock determination is performed. In addition, it is possible to prevent erroneous determination that the vibration intensity is increased due to valve operating noise (noise due to the operation of the intake valve 30 or the exhaust valve 31) as knocking (with knocking), and to improve knock detection accuracy. it can. In addition, since it is not necessary to change the valve timing according to the knock determination period, the valve timing can be set to an appropriate time according to various requirements (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.).

  Further, regardless of whether or not the knock determination period and the valve train noise period overlap (that is, whether or not the valve train noise enters the knock determination period), the vibration intensity and the valve train in the knock determination period The knock determination value can be set based on the larger vibration intensity of the vibration intensity in the system noise period, so when the valve system noise enters the knock determination period due to the change in valve timing or from the knock determination period Even when it comes out, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  In the third embodiment, since the valve operating noise period is set to a period including the closing noise of the intake valve 30 and the exhaust valve 31, the vibration of the closing noise of the intake valve 30 and the exhaust valve 31 is set. A knock determination value considering the strength can be set, and a state in which the vibration intensity is increased due to valve closing noise of the intake valve 30 or the exhaust valve 31 can be prevented from being erroneously determined as knocking.

  Next, Embodiment 4 of the present invention will be described with reference to FIG. However, description of substantially the same parts as in the third embodiment will be omitted or simplified, and different parts from the third embodiment will be mainly described.

  In the fourth embodiment, the ECU 34 executes a knock determination routine of FIG. 7 to be described later, so that the operation region where the influence of the valve system noise on the output signal of the knock sensor 27 is large (that is, the vibration intensity of the valve system noise is reduced). When it is determined that there is no knocking in the operation region where the ground level is larger) (when knocking is not performed), the vibration intensity of the valve train noise is learned, and the influence of the valve train noise on the output signal of the knock sensor 27 is large. When the knock determination is performed in the operation region, the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the valve operating noise.

  In the knock determination routine of FIG. 7, first, in step 401, the vibration intensity in the knock determination period (for example, the peak hold value of the output signal of the knock sensor 27) is calculated, and then the process proceeds to step 402 to output the output signal of the knock sensor 27. For example, whether the engine rotation speed is lower than a predetermined value or not is an operation region where the influence of the valve system noise is large (that is, an operation region where the vibration intensity of the valve system noise is greater than the background level). Judgment is made based on whether or not the vehicle is in the operating region.

  When it is determined in step 402 that the operating region is greatly affected by the valve operating noise on the output signal of the knock sensor 27 (that is, the operating region in which the vibration intensity of the valve operating noise is greater than the background level). Advances to step 403, reads the learned value of the vibration intensity of the valve system noise learned by the method described later, and then proceeds to step 404 to set the learned value of the vibration intensity of the valve system noise u times (for example, 3 times). ) Is calculated as a knock determination value.

  Thereafter, the process proceeds to step 405, where it is determined whether or not the vibration intensity in the knock determination period is greater than the knock determination value. If it is determined that the vibration intensity is greater than the knock determination value, the process proceeds to step 406. It is determined that there is a knock.

  On the other hand, if it is determined in step 405 that the vibration intensity is equal to or less than the knock determination value, the process proceeds to step 407, and after determining that there is no knock, the process proceeds to step 408, where the vibration intensity of the valve operating noise is set to the following. Learn like this. The vibration intensity data is statistically processed by repeating the process of calculating the vibration intensity (for example, the peak hold value of the output signal of the knock sensor 27) in a predetermined period (for example, valve system noise period) a predetermined number of times or a predetermined cycle. Then, the vibration intensity distribution is determined, and the value of a predetermined percentage point (for example, 97% point) of the vibration intensity distribution is learned as the vibration intensity of the valve operating noise. The learned value of the vibration intensity of the valve system noise is stored in a rewritable nonvolatile memory such as a backup RAM of the ECU 34.

  On the other hand, if it is determined in step 402 that the operating region is not greatly affected by the valve train noise on the output signal of the knock sensor 27, the process proceeds to step 409, where normal knock determination is performed.

  In the fourth embodiment described above, the vibration intensity of the valve operating noise is learned in the knock-free state, and the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the valve operating noise. Therefore, it is possible to prevent erroneous determination that knocking occurs (with knocking) when the vibration intensity has increased due to valve operating system noise, improving knock detection accuracy and knocking the valve timing. Since there is no need to change according to the determination period, the valve timing can be set to an appropriate time according to various requirements (for example, fuel consumption reduction, exhaust emission reduction, oil dilution prevention, etc.). In addition, the knock determination value can be set based on the learned value of the vibration intensity of the valve operating noise regardless of whether or not the valve operating noise has entered the knock determination period. Even when the valve system noise enters or exits the knock determination period, the knock determination value can be maintained at an appropriate level, and the knock detection accuracy at the time of transition can be ensured.

  Further, in the fourth embodiment, it is determined that there is no knock in the operation region where the influence of the valve system noise on the output signal of the knock sensor 27 is large (that is, the operation region where the vibration intensity of the valve system noise is greater than the background level). Since the vibration intensity of the valve operating noise is learned when the engine is knocked (when there is no knock), the vibration intensity of the valve operating noise can be learned with high accuracy.

  Furthermore, in the fourth embodiment, the knock determination is performed in an operation region where the influence of the valve system noise on the output signal of the knock sensor 27 is large (that is, an operation region where the vibration intensity of the valve system noise is greater than the background level). In this case, since the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the valve system noise, the state in which the vibration intensity is increased due to the valve system noise is mistaken as a knock occurrence. It is possible to reliably prevent the determination.

  In the fourth embodiment, when it is determined that there is no knock in the operation region where the influence of the valve system noise on the output signal of the knock sensor 27 is large, the vibration intensity of the valve system noise is learned and the output signal of the knock sensor 27 is detected. When knock determination is performed in an operating region where the influence of valve system noise is large, knock determination is performed using the knock determination value calculated based on the learned value of vibration intensity of valve system noise. Without being limited thereto, the vibration intensity of the valve system noise is learned when it is determined that there is no knock in a frequency band in which the influence of the valve system noise on the output signal of the knock sensor 27 is large, and the valve system for the output signal of the knock sensor 27 is determined. When knock determination is performed in a frequency band where the influence of noise is large, the knock determination is performed using the knock determination value calculated based on the learned value of the vibration intensity of the valve operating noise. It may be.

  In addition, the knock determination value calculated based on the learned value of the vibration intensity of the valve operating noise is used regardless of whether the operating range or the frequency band is greatly affected by the valve operating noise on the output signal of the knock sensor 27. It may be used to make a knock determination.

  In each of the third and fourth embodiments, the knock determination value is calculated based on the vibration intensity of the closing noise of the intake valve 30 and the exhaust valve 31. However, the present invention is not limited to this, and the intake valve and the exhaust valve are not limited thereto. When noise having a vibration intensity larger than the valve closing noise is generated by the above operation, the knock determination value may be calculated based on the vibration intensity of the noise.

  Further, by combining the first embodiment and the third embodiment, the knock determination is made based on the largest vibration intensity among the vibration intensity in the knock determination period, the vibration intensity in the injection valve noise period, and the vibration intensity in the valve train noise period. A value may be calculated.

  In addition, combining the second embodiment and the fourth embodiment, learning the vibration intensity of the injection valve noise and the vibration intensity of the valve system noise when there is no knock, and learning value of the vibration intensity of the injection valve noise; The knock determination value may be calculated based on the learned value of the vibration intensity of the valve train noise.

  In addition, the present invention is not limited to the in-cylinder injection engine as shown in FIG. 1, but includes an intake port injection engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 27 ... Knock sensor, 29 ... Crank angle sensor, 30 ... Intake valve, 31 ... Exhaust valve, 34 ... ECU (knock determination means)

Claims (11)

Knock determination of an internal combustion engine provided with a knock determination means for calculating vibration intensity based on an output signal of a knock sensor for detecting knock vibration of the internal combustion engine and comparing the vibration intensity with a knock determination value to determine the presence or absence of knock In the device
The knock determination means calculates a vibration intensity in a predetermined knock determination period, calculates a vibration intensity in a period including noise due to the operation of the fuel injection valve (hereinafter referred to as “injection valve noise period”), and performs the knock determination period. A knock determination device for an internal combustion engine, wherein the knock determination value is calculated based on a larger vibration intensity between a vibration intensity in the injection valve and a vibration intensity in the injection valve noise period.   The knock determination means sets the injection valve noise period to a period including at least valve opening noise among valve opening noise generated by the valve opening operation of the fuel injection valve and valve closing noise generated by the valve closing operation. The knock determination device for an internal combustion engine according to claim 1.   When the knock determination means calculates the vibration intensity during the injection valve noise period during the execution of the divided injection for dividing and injecting the fuel into a plurality of times, one of the plurality of divided injections is performed. The knock determination device for an internal combustion engine according to claim 1 or 2, wherein the vibration intensity in the injection valve noise period of one injection is calculated. Knock determination of an internal combustion engine provided with a knock determination means for calculating vibration intensity based on an output signal of a knock sensor for detecting knock vibration of the internal combustion engine and comparing the vibration intensity with a knock determination value to determine the presence or absence of knock In the device
The knock determination means learns the vibration intensity of noise (hereinafter referred to as “injection valve noise”) due to the operation of the fuel injection valve when there is no knock, and based on the learned value of the vibration intensity of the injection valve noise, A knock determination apparatus for an internal combustion engine, characterized by calculating a determination value.   The knock determination means learns the vibration intensity of the injection valve noise when it is determined that there is no knock in an operating region or frequency band where the influence of the injection valve noise on the output signal of the knock sensor is large. Item 5. The knock determination device for an internal combustion engine according to Item 4.   When the knock determination means performs a knock determination in an operating region or frequency band where the influence of the injection valve noise on the output signal of the knock sensor is large, a knock calculated based on a learning value of the vibration intensity of the injection valve noise 6. The knock determination device for an internal combustion engine according to claim 4, wherein a determination value is used. Knock determination of an internal combustion engine provided with a knock determination means for calculating vibration intensity based on an output signal of a knock sensor for detecting knock vibration of the internal combustion engine and comparing the vibration intensity with a knock determination value to determine the presence or absence of knock In the device
The knock determination means calculates a vibration intensity during a predetermined knock determination period and calculates a vibration intensity during a period including noise due to the operation of the intake valve and / or the exhaust valve (hereinafter referred to as a “valve system noise period”). A knock determination device for an internal combustion engine, wherein the knock determination value is calculated based on a vibration intensity that is larger of a vibration intensity in the knock determination period and a vibration intensity in the valve train noise period.   The internal combustion engine according to claim 7, wherein the knock determination means sets the valve operating noise period to a period including valve closing noise generated by valve closing operation of the intake valve and / or the exhaust valve. Engine knock determination device. Knock determination of an internal combustion engine provided with a knock determination means for calculating vibration intensity based on an output signal of a knock sensor for detecting knock vibration of the internal combustion engine and comparing the vibration intensity with a knock determination value to determine the presence or absence of knock In the device
The knock determination means learns the vibration intensity of noise (hereinafter referred to as “valve system noise”) due to the operation of the intake valve and / or the exhaust valve when there is no knock, and learns the vibration intensity of the valve system noise. A knock determination device for an internal combustion engine, wherein the knock determination value is calculated based on a value.   The knock determination means learns the vibration intensity of the valve operating noise when it is determined that there is no knock in an operating region or frequency band where the influence of the valve operating noise on the output signal of the knock sensor is large. The knock determination device for an internal combustion engine according to claim 9.   The knock determination means calculates based on a learning value of the vibration intensity of the valve operating noise when performing knock determination in an operation region or frequency band where the influence of the valve operating noise on the output signal of the knock sensor is large. The knock determination device for an internal combustion engine according to claim 9 or 10, wherein the knock determination value is used.

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