JP2002364446A - Knocking detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To not only detect presence or absence of knocking generation but also easily determine the knocking due to abnormal combustion or pseudo knocking. SOLUTION: Combustion pressure (cylinder pressure) inside a combustion chamber is detected by a cylinder pressure sensor as a vibration generated in accompanied with an operation of the internal combustion engine, and from a pressure waveform signal, a signal in a frequency band peculiar to knocking is filtered by a filter. A vibration strength after filtering is compared with a knock determination level, thereby determining whether or not the knocking is generated (step 110). When generation of knocking is determined to be present, a maximum value Pmax of the cylinder pressure detected by the cylinder pressure sensor within a predetermined period relative to combustion is compared with a determination value α(step 130). When the maximum value Pmax is smaller than the determination value α, determination that the knocking is the pseudo knocking is carried out (step 140), and the maximum value Pmax is more than the determination value α, the determination that the knocking is real knocking due to the abnormal combustion is carried out (step 150).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking detection device for an internal combustion engine that detects knocking that occurs during operation of the internal combustion engine.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine, after the combustion pressure becomes maximum due to abnormal combustion in a combustion chamber, the internal combustion engine is forced to operate for 6 hours.
Pressure vibration called knocking may occur in a frequency band such as about 9 kHz or about 14 kHz. Knocking can cause overheating and melting of the electrodes of the spark plug and the piston. Therefore, the above-mentioned problem is dealt with by performing knocking control.

In knocking control, a vibration generated within a predetermined period after the combustion pressure reaches a maximum is detected by a knock sensor, and a vibration waveform signal from the sensor is filtered (extracted) by a filter. The vibration intensity near the center frequency after the filtering is compared with a predetermined knock determination level. The center frequency is a frequency at which the vibration intensity becomes maximum when knocking occurs. If the vibration intensity is higher than the knock determination level, it is determined that knocking has occurred. If the vibration intensity is equal to or lower than the knock determination level, it is determined that knocking has not occurred. Such a knocking detection technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-193333. In this publication, the presence or absence of knocking is determined by comparing the integrated value of the output signal of the in-cylinder pressure sensor with the knock determination level.

When it is determined that knocking has occurred, the ignition timing is delayed (retarded), and the occurrence of knocking is suppressed. If it is determined that knocking has not occurred, the ignition timing is advanced (advanced),
The engine output and fuel efficiency are improved. Further, when it is determined that knocking has occurred, the fuel injection amount to the engine may be temporarily increased and corrected to reduce the air-fuel ratio instead of the ignition timing. In this case, the temperature in the combustion chamber decreases due to the increase in the fuel injection amount, and knocking is suppressed.

[0005]

However, according to the prior art including the above-mentioned publication, it is possible to determine whether knocking has occurred or not. It is difficult to judge whether this is so-called “pseudo knocking”. Here, knocking due to abnormal combustion tends to occur by advancing the ignition timing or increasing the air-fuel ratio, whereas pseudo knocking occurs by retarding the ignition timing or reducing the air-fuel ratio. Easier to do. Therefore, when it is determined that knocking has occurred due to the occurrence of pseudo knocking, if processing for suppressing knocking due to abnormal combustion, for example, processing for delaying the ignition timing is erroneously performed, pseudo knocking is not suppressed. It gets worse. In order to solve this problem, it is important to determine both knocking and to perform an appropriate process for suppressing the knocking for each knocking.

In some internal combustion engines, the center frequency of pseudo knocking may not match the center frequency of knocking due to abnormal combustion. In this case, by using the latter vibration intensity near the center frequency for comparison with the knock determination level, knocking can be detected after discrimination between knocking due to abnormal combustion and pseudo knocking. However, in this method, it is necessary to verify whether or not the center frequencies do not always match for each internal combustion engine.

The present invention has been made in view of such circumstances, and its object is to not only detect the occurrence of knocking but also to easily determine knocking due to abnormal combustion and pseudo knocking. An object of the present invention is to provide a knocking detection device for an internal combustion engine.

[0008]

The means for achieving the above object and the effects thereof will be described below. According to the first aspect of the present invention, a vibration detecting means for detecting vibration generated with the operation of the internal combustion engine, and a signal in a frequency band specific to knocking is filtered by a filter from a vibration waveform signal by the vibration detecting means. First determining means for determining whether or not knocking has occurred by comparing the vibration intensity with the knock determination level; combustion pressure detecting means for detecting a combustion pressure that changes with combustion of the air-fuel mixture in the internal combustion engine; (1) When it is determined that knocking has occurred by the determination means, the knocking is performed by knocking due to abnormal combustion and abnormal combustion based on the maximum value of the combustion pressure detected by the combustion pressure detecting means during a predetermined period related to the combustion. And a second determination unit for determining which of the pseudo knocking is not performed.

According to the above arrangement, the vibration generated during operation of the internal combustion engine is detected by the vibration detecting means. The vibrations include those caused by abnormal combustion (so-called knocking) and those caused by mechanical vibration of the internal combustion engine without abnormal combustion (so-called pseudo knocking). In the first determining means, a signal in a frequency band peculiar to knocking is filtered by a filter from the vibration waveform signal by the vibration detecting means. The presence or absence of knocking is determined by comparing the vibration intensity after filtering with the knock determination level. At this stage, not only when knocking due to abnormal combustion has occurred but also when pseudo knocking has occurred, it may be determined that knocking has occurred.

[0010] Here, when knocking due to abnormal combustion occurs, the combustion pressure sharply increases and a clear pressure peak is observed. On the other hand, when pseudo knocking occurs, such a clear pressure peak occurs. No pressure peak is seen. Therefore, it is possible to determine both knocking based on the presence or absence of a clear pressure peak.

From this, the combustion pressure that changes with the combustion of the air-fuel mixture in the internal combustion engine is detected by the combustion pressure detecting means. When the knocking is determined to occur by the first determining means, the second determining means further sets the maximum value (pressure peak) of the combustion pressure detected by the combustion pressure detecting means in a predetermined period related to the combustion. Based on this, it is determined whether knocking is due to abnormal combustion or pseudo knocking.

As described above, according to the first aspect of the present invention, it is possible not only to detect the occurrence of knocking based on the vibration of the internal combustion engine, but also to easily determine whether the knocking is knocking due to abnormal combustion or pseudo knocking. be able to.

According to a second aspect of the present invention, in the first aspect of the present invention, the second determining means performs a pseudo operation when a maximum value of the combustion pressure by the combustion pressure detecting means is smaller than a predetermined determination value. It is assumed that knocking is determined.

According to the above configuration, in the second determination means,
The maximum value of the combustion pressure detecting means is compared with a predetermined judgment value. Here, for example, the maximum value of the pressure peak that can be taken when pseudo knocking occurs and the minimum value of the pressure peak that can be taken when knocking due to abnormal combustion occurs are used, and an intermediate value between them is determined. It can be a value. In this case, when the maximum value of the combustion pressure by the combustion pressure detecting means is smaller than the determination value, it is determined that the engine is in a quasi-knocking state.

According to a third aspect of the present invention, in the second aspect of the present invention, it is assumed that the determination value is set based on an average value of the combustion pressure by the combustion pressure detecting means.

According to the above configuration, the average value of the combustion pressure by the combustion pressure detecting means is used as a determination value for determining knocking and pseudo knocking due to abnormal combustion. Therefore, even if noise is superimposed on the detection signal of the combustion pressure detecting means before the determination, the influence of the noise on the setting of the determination value can be reduced. Along with this,
By setting a highly accurate determination value, knocking and pseudo knocking due to abnormal combustion can be more reliably determined.

According to the invention described in claim 4, claims 1 to 3 are provided.
In the invention described in any one of the above, it is assumed that the vibration detecting means and the combustion pressure detecting means are constituted by an in-cylinder pressure sensor for detecting a pressure in a cylinder of the internal combustion engine.

According to the above arrangement, the in-cylinder pressure sensor functions as both the vibration detecting means and the combustion pressure detecting means. For this reason, it is possible to detect knocking occurrence and determine knocking due to abnormal combustion and pseudo knocking with a small number of sensors.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a knocking detection device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

An internal combustion engine 11 shown by a two-dot chain line in FIG.
In the above, a mixture of fuel and air introduced into a combustion chamber and compressed by a piston is ignited and burned by sparks of a spark plug. Combustion is performed by a flame propagating through the mixture. The piston reciprocates in the cylinder by the heat energy accompanying the combustion. The reciprocating motion is converted into a rotary motion, and the crankshaft, which is the output shaft of the internal combustion engine 11, is driven to rotate.

In the internal combustion engine 11, the in-cylinder pressure P, which is the pressure in the cylinder (combustion chamber), increases with the combustion as shown in FIG.
Changes as shown in FIG. As is clear from FIG.
The in-cylinder pressure P is a crank angle (C
A) becomes maximum when T) is near TDC (the position where the piston is farthest from the crankshaft). But,
If the pressure becomes abnormally high during the propagation of the flame, so-called knocking may occur, in which the flame self-ignites and burns at a time without waiting for the propagation of the flame. In this case, the pressure rise caused by the rapid combustion oscillates the gas in the combustion chamber. Such knocking generally occurs after the in-cylinder pressure P reaches a maximum, as indicated by a two-dot chain line in FIG.
That is, it occurs within a predetermined period T after the crank angle has passed the top dead center TDC, for example, in ATDC10 to 30CA. When knocking occurs, heat is easily transmitted by the vibration of the combustion gas. If this state continues, the electrodes of the ignition plug and the piston may be overheated and melted.

FIGS. 3A and 3B show the intensity of vibration generated in the internal combustion engine 11 during the predetermined period T. FIG. When knocking does not occur, the vibration intensity does not change much regardless of the frequency as shown in FIG. In contrast,
When knocking occurs, the vibration intensity increases in a frequency band around 6 kHz, a frequency band around 12 kHz, and the like as shown in FIG. The frequency (center frequency) at which the vibration intensity increases as described above is determined according to a predetermined arithmetic expression using the diameter of the cylinder bore, the combustion temperature, and the like as parameters.

There is a close relationship between the ignition timing and the occurrence of knocking. If the ignition timing is advanced (advanced), the maximum value of the combustion pressure increases, and knocking easily occurs. Further, although not as much as the ignition timing, a close relationship is seen between the air-fuel ratio (the weight ratio of air and fuel in the air-fuel mixture) and the occurrence of knocking. When the air-fuel ratio increases (the mixture becomes thinner), knocking tends to occur.

The knocking due to abnormal combustion is hereinafter referred to as "true knocking" to distinguish it from pseudo knocking described later. In addition, when there is no particular distinction between both knocking, it is simply referred to as “knocking”.

As a phenomenon similar to the true knocking described above, there is a pseudo knocking caused by mechanical noise of the internal combustion engine 11. The mechanical noise includes, for example, vibration of the main body of the internal combustion engine, vibration due to seating of the intake / exhaust valves, mechanical vibration due to rotation, and the like. Also in this pseudo knocking, the intensity of vibration increases in a specific frequency band similarly to the true knocking. The center frequency of the pseudo knocking differs depending on the type of the internal combustion engine 11, and may or may not match the center frequency of the true knocking. Differences between the pseudo knocking and the true knocking include a correlation with the ignition timing and a correlation with the air-fuel ratio. When the ignition timing is delayed (retarded) or when the air-fuel ratio is reduced (the mixture is made rich), pseudo knocking tends to occur easily.

The following points are different from true knocking. When a true knock occurs, the output increases and the in-cylinder pressure P increases because the ignition timing has advanced beyond the proper timing. As shown in FIG. 4, the in-cylinder pressure P sharply increases and a clear pressure peak is observed. On the other hand, in the pseudo knocking, since the ignition timing is later than the appropriate timing, the output does not increase and the in-cylinder pressure P does not increase so much. That is, in the pseudo knocking, as shown in FIG. 5, a clear peak of the in-cylinder pressure P unlike the true knocking is not seen.

As shown in FIG. 1, the internal combustion engine 11 is provided with an in-cylinder pressure sensor 12 for detecting an in-cylinder pressure P as a means for detecting vibration and a means for detecting combustion pressure.
As the in-cylinder pressure sensor 12, for example, a seat-type in-cylinder pressure sensor, a direct insertion type combustion pressure sensor, or the like can be used. The seat-type in-cylinder pressure sensor is mounted on the internal combustion engine 11 while being fastened to the seat of the spark plug. In this type, the ignition pressure is pushed up by the combustion pressure, and the tightening load on the in-cylinder pressure sensor changes. The electric charge corresponding to the change in the tightening load is output as a corresponding value of the combustion pressure. The direct insertion type combustion pressure sensor generally includes a diaphragm, a pressure transmission rod, and a pressure-sensitive element, and detects the pressure in the combustion chamber without passing through a transmission path in the air.

The in-cylinder pressure sensor 12 is connected via a band pass filter (hereinafter referred to as “BPF”) 13 or directly to an electronic control unit (Electronic Control Unit).
nit (hereinafter referred to as “ECU”) 14.
The BPF 13 filters (extracts) a signal in a frequency band unique to knocking from the pressure waveform signal detected by the in-cylinder pressure sensor 12 shown in FIG. FIG. 3A shows a waveform signal after filtering when knocking has not occurred, and FIG.
(B) shows a waveform signal after filtering when knocking has occurred.

The ECU 14 shown in FIG. 1 is mainly composed of a microcomputer, and has a central processing unit (CPU).
Performs arithmetic processing according to a control program, initial data, a control map, and the like stored in a read-only memory (ROM), and executes various controls based on the arithmetic results. The calculation result by the CPU is temporarily stored in a random access memory (RAM). ECU 14
Is provided with an analog / digital (A / D) converter 15 for converting a signal (analog value) filtered by the BPF 13 and a detection value of the in-cylinder pressure sensor 12 into a digital value.

Various sensors 16 for detecting the operating state of the internal combustion engine 11 are connected to the ECU 14. The various sensors 16 include, for example, a crank angle sensor that outputs a signal each time the crankshaft rotates by a certain angle, a cylinder discrimination sensor for specifying a cylinder that is a knock detection target, and an intake air that detects an intake air amount. Examples include an amount sensor and a water temperature sensor for detecting a cooling water temperature. Among these detection signals, detection signals (analog values) of the intake air amount sensor, the water temperature sensor, and the like are converted into digital values by the A / D converter 15.

Further, an igniter 17, an injector 18 and the like provided in the internal combustion engine 11 are connected to the ECU 14. The ECU 14 basically calculates an ignition timing, a fuel injection amount, and the like based on the detection signals from the various sensors 16 described above, and drives and controls the igniter 17, the injector 18, and the like according to the calculation results. The ECU 14
Is based on the detection value of the in-cylinder pressure sensor 12 (more precisely, filtered by the BPF 13 and the A / D converter 15
(Based on the A / D converted value) to detect the occurrence of knocking. Further, when the occurrence of knocking is detected, it is determined whether the knocking is true knocking or pseudo knocking.

Then, the ECU 14 performs a process for achieving both the suppression of knocking and the improvement of engine output, fuel efficiency and the like based on the detection result and the discrimination result. For example,
When it is determined that true knocking has occurred, the ignition timing is retarded, and when it is determined that pseudo knocking has occurred, the ignition timing is advanced. Knocking is suppressed by correcting these ignition timings. When it is determined that neither knocking has occurred, the ignition timing is advanced and the engine output and fuel consumption are improved.

Next, a procedure for detecting occurrence of knocking and determining whether the knocking is true knocking or pseudo knocking will be described. FIG.
9 shows a "knocking detection routine" executed by the ECU 14, which is executed at a predetermined timing, for example, every predetermined crank angle or every predetermined time.

First, at step 110, the ECU 14 determines whether or not there is a peak near the center frequency of knocking, more specifically, whether or not the vibration intensity around the same frequency is larger than the knock determination level. As the knock determination level, for example, a value obtained by calculating an average value of vibration intensity after filtering by the BPF 13 and multiplying the average value by a predetermined coefficient can be used. If the determination condition in step 110 is not satisfied, it is determined in step 160 that no knocking has occurred.

On the other hand, if the condition of step 110 is satisfied, either true knocking or pseudo knocking has occurred. So, in this case,
In steps 120 to 150, it is determined which knocking is occurring. In step 120, the pressure average value P
Calculate ave. For example, the detection values of the in-cylinder pressure sensor 12 are stored for each predetermined crank angle, and the average value thereof is obtained in step 120, and this is set as the pressure average value Pave.

In step 130, it is determined whether or not the maximum value Pmax of the in-cylinder pressure P by the in-cylinder pressure sensor 12 is smaller than a predetermined determination value α during a predetermined period T after the top dead center TDC. Here, for example, using the maximum value of the pressure peak that can be taken when pseudo knocking occurs and the minimum value of the pressure peak that can be taken when true knocking occurs, an intermediate value between them is used as the determination value α. It can be. The determination value α is set, for example, by multiplying the average pressure value Pave by a predetermined coefficient R. Coefficient R
Is for converting the pressure average value Pave into the determination value α, and varies depending on the type of the internal combustion engine 11, operating conditions, and the like.

If the judgment condition of step 130 is satisfied (Pmax <α), there is no clear pressure peak for the in-cylinder pressure P as shown in FIG.
In, it is determined that the knocking is due to pseudo knocking. On the other hand, if the determination condition in step 130 is not satisfied (Pmax ≧ α), there is a clear pressure peak for the in-cylinder pressure P as shown in FIG. Is determined. Then, after going through any one of steps 140, 150, and 160, the knocking detection routine is terminated. Step 14
The determination results of 0 to 160 are used for ignition timing control, fuel injection control, and the like in another routine as described above.

As described above, in the knocking detection routine, the ECU 14 functions as means for determining whether knocking has occurred by comparing the vibration intensity after filtering by the BPF 13 with the knock determination level. Also, E
The CU 14 determines the maximum value Pma of the in-cylinder pressure P during the predetermined period T.
It functions as means for determining true knocking and pseudo knocking based on x.

According to the above-described embodiment, the following effects can be obtained. (1) When true knocking occurs, the combustion pressure sharply increases and a clear pressure peak is observed, whereas when pseudo knocking occurs, such a clear pressure peak is observed. I can't. Focusing on this phenomenon, in the present embodiment, when it is determined that knocking has occurred, it is determined whether or not there is a more clear pressure peak (step 130). Therefore, not only can the knocking be detected based on the vibration of the internal combustion engine 11, but also whether the knocking is true knocking or pseudo knocking can be easily determined.

(2) As the combustion pressure detecting means, an in-cylinder pressure sensor 12 for directly detecting the in-cylinder pressure P is used. For this reason, knocking occurs after the in-cylinder pressure P reaches a maximum. The in-cylinder pressure sensor 12 can accurately grasp the time when the in-cylinder pressure P reaches a maximum. Therefore, based on the subsequent in-cylinder pressure P, it is possible to reliably determine whether the knocking is true knocking or pseudo knocking.

(3) An in-cylinder pressure sensor is used as a means for detecting vibration and a means for detecting combustion pressure. For this reason, it is possible to detect the occurrence of knocking and discriminate between true knocking and pseudo knocking with a small number of sensors.

(4) As described above, the relationship between the ignition timing and the occurrence of knocking and the countermeasures for suppressing knocking are reversed in true knocking and pseudo knocking.
In the present embodiment, true knocking and pseudo knocking can be determined as described above. Therefore, when it is determined that knocking has occurred due to the occurrence of pseudo knocking, it is possible to avoid erroneous processing for suppressing true knocking, for example, processing for delaying the ignition timing. In this case, pseudo knocking can be reliably suppressed by performing processing such as advancing the ignition timing or increasing the air-fuel ratio (thinning the air-fuel mixture).

(5) The average pressure value Pave is used to set the judgment value α. Therefore, even if noise is superimposed on the detection value of the in-cylinder pressure sensor 12 before discrimination between true knocking and pseudo knocking, the influence of the noise on the setting of the determination value α can be reduced. Accordingly, a highly accurate determination value α is set, and true knocking and pseudo knocking can be more reliably determined.

(6) Even if the center frequency of the pseudo knocking differs for each type of the internal combustion engine 11, it is possible to determine the true knocking and the pseudo knocking by using the knocking detection device of the present embodiment. Therefore, unlike the related art, it is not necessary to verify whether the center frequency of the true knocking and the center frequency of the pseudo knocking may not match for each internal combustion engine.

(7) When knocking due to abnormal combustion occurs, the knocking occurs for a predetermined period TDC after the top dead center TDC.
Limited to From this, in the present embodiment, the top dead center TD
The maximum value of the in-cylinder pressure P during a predetermined period T after C is set as the maximum value Pmax of the in-cylinder pressure P used for determining knocking. Therefore, it is possible to prevent the maximum value of the combustion pressure in a period different from the predetermined period T from being used for the determination of the pseudo knocking, and to suppress a decrease in the determination accuracy.

The present invention can be embodied in another embodiment described below. -In-cylinder pressure P is essential to determine true knocking and pseudo knocking, but in-cylinder pressure P is not essential to determine whether knocking has occurred. Instead of the in-cylinder pressure P, vibration of the internal combustion engine may be detected. Therefore, from this viewpoint, for example, a knock sensor may be used in addition to the in-cylinder pressure sensor.

In order to determine the true knocking and the pseudo knocking, it is sufficient to know the degree of the maximum value Pmax of the in-cylinder pressure P after the top dead center TDC. Therefore, the determination value α for this determination is not limited to the value set based on the average pressure value Pave as in the above embodiment. Instead of the pressure average value Pave, the determination value α may be set based on the minimum and maximum values of the in-cylinder pressure P before the determination. However, in this case, in order to reduce the influence of the instantaneous abnormal value, as many minimum values or maximum values as possible are sampled, and those obtained by averaging are sampled to obtain the minimum value for setting the determination value α. It is desirable to set the value or the maximum value.

In addition, technical ideas that can be grasped from the above embodiments will be described together with their effects.
(A) In the knocking detection device for an internal combustion engine according to claim 1, the second determination means determines a maximum value in a predetermined period after a top dead center of the internal combustion engine among detection values of the combustion pressure detection means. Is used as the maximum value of the combustion pressure for pseudo knocking determination.

When knocking due to abnormal combustion occurs, the knocking is limited to a predetermined period after the top dead center.
Therefore, according to the above configuration, it is possible to prevent the maximum value of the combustion pressure in a period different from the predetermined period from being used for the determination of the pseudo knocking, and to suppress a decrease in the determination accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment embodying a knocking detection device for an internal combustion engine of the present invention.

FIG. 2 is a waveform chart showing a change in in-cylinder pressure.

3 (a) and 3 (b) are waveform diagrams showing vibration intensity after filtering by a BPF.

FIG. 4 is a waveform chart showing a change in in-cylinder pressure when true knocking occurs.

FIG. 5 is a waveform diagram showing a change in in-cylinder pressure when pseudo knocking occurs.

FIG. 6 is a flowchart illustrating a procedure for detecting knocking.

[Explanation of symbols]

11: internal combustion engine, 12: in-cylinder pressure sensor, 13: band-pass filter, 14: electronic control unit (ECU), α: determination value, T: predetermined period.

Continued on front page F-term (reference) 2G087 AA27 BB12 CC12 CC15 FF04 FF22 FF25 3G019 AB01 AB02 DA02 DB02 DB07 GA01 GA05 GA11 GA14 KA28 KD17 LA11 3G084 BA09 BA13 BA17 DA02 DA38 EA01 EA02 EA05 EA11 FA21 FA20 FA20 FA20 FA20

Claims (4)

[Claims] 1. A vibration detecting means for detecting vibration generated during operation of an internal combustion engine, and a signal in a frequency band peculiar to knocking is filtered by a filter from a vibration waveform signal from the vibration detecting means, and a vibration intensity after the filtering is obtained. A first determination unit that determines whether knocking has occurred by comparing with a knock determination level; a combustion pressure detection unit that detects a combustion pressure that changes with combustion of the air-fuel mixture in the internal combustion engine; When it is determined that knocking has occurred, the knocking is performed based on the maximum value of the combustion pressure detected by the combustion pressure detecting means during a predetermined period related to the combustion, based on the knocking due to abnormal combustion and the pseudo knocking not due to abnormal combustion. A knocking detection device for an internal combustion engine, comprising: a second determination unit configured to determine which one of the two is the knocking detection device. 2. The internal combustion engine according to claim 1, wherein said second judging means judges pseudo knocking when the maximum value of the combustion pressure by said combustion pressure detecting means is smaller than a predetermined judgment value. Knock detection device. 3. The determination value is set based on an average value of the combustion pressure by the combustion pressure detection means.
A knocking detection device for an internal combustion engine according to claim 1. 4. The internal combustion engine according to claim 1, wherein said vibration detecting means and said combustion pressure detecting means comprise an in-cylinder pressure sensor for detecting a pressure in a cylinder of said internal combustion engine. Knock detection device for engines.