JPH0765558B2 - Abnormal combustion detection device and combustion control device for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal combustion detection device and a combustion control device for an internal combustion engine, and more particularly to an abnormal combustion detection device and an abnormal combustion detection device that detect abnormal combustion caused by so-called hot surface ignition. The present invention relates to a combustion control device that suppresses the abnormal combustion when detected.

(Prior Art) In an internal combustion engine equipped with an ignition timing control device, the ignition timing of the air-fuel mixture supplied to the cylinder is set to an engine operating condition such that the engine drivability and exhaust gas characteristics are optimized. However, when the engine is actually operated, abnormal combustion in which the air-fuel mixture in the cylinder starts combustion at a timing earlier than the set ignition timing, so-called preignition occurs. It is known.

This pre-ignition not only significantly deteriorates the drivability of the engine, but also may damage the engine, and the probability of occurrence increases with the high performance of the engine, the high output, and the use of methanol fuel in recent years. Is coming.

One of the causes of this abnormal combustion is so-called hot surface ignition, in which the compressed air-fuel mixture is ignited by the heat of the surface of the overheated spark plug, the inner wall of the cylinder, etc. before the spark discharge is performed. When a methanol fuel (alcohol mixed fuel), which has been researched and developed for environmental and energy conservation in recent years, is used for an internal combustion engine, the possibility of abnormal combustion of the engine due to the hot surface ignition becomes even greater.

For this reason, conventionally, an abnormal combustion detecting means configured to detect the combustion state of the air-fuel mixture in the combustion chamber of the internal combustion engine, for example, the ion current associated with combustion in the combustion chamber (Japanese Patent Laid-Open No. 55-75629).
No.) to avoid abnormal combustion.

(Problems to be Solved by the Invention) In hot surface ignition, the flame surface is generated before the normal ignition timing by spark ignition of the spark plug (advance side), but the ignition spark is changed to the normal ignition timing. When not skipped in, the ignition timing is classified into pre-ignition and post-ignition depending on whether it is after the normal ignition timing (retard side). It is known that the timing of flame surface generation due to post ignition gradually advances as the temperature of the heat surface such as the cylinder inner wall rises, and eventually reaches preignition. Therefore, if the occurrence of post ignition is detected, the possibility of occurrence of pre-ignition can be estimated. However, the timing of the post-ignition flame front occurs after a portion of the air-fuel mixture begins to burn due to spark ignition of the spark plug, so the timing of the post-ignition occurrence is the timing at which combustion of the air-fuel mixture in the cylinder starts. It cannot be detected based on.

On the other hand, preignition is a phenomenon in which combustion of the air-fuel mixture in the cylinder starts before spark ignition of the spark plug occurs, and as described above, the flame of the air-fuel mixture is burned in the entire cylinder before the engine finishes the compression stroke. During the compression stroke, an explosion may occur and damage the engine structure. In this pre-ignition, the air-fuel mixture in the cylinder abnormally burns before the spark ignition by the spark plug as described above.Therefore, it is possible to detect the occurrence of the air-fuel mixture based on the timing at which the air-fuel mixture starts burning. However, once a preignition occurs, it may directly lead to the destruction of the engine, so it is necessary to take some measures to prevent the preignition.

(Object of the Invention) The present invention has been made in view of the above circumstances, and an abnormal combustion detection device for an internal combustion engine that enables detection of post ignition and estimates the possibility of preignition depending on the state of occurrence of post ignition. It is also an object of the present invention to provide a combustion control device for an internal combustion engine, which prevents the occurrence of pre-ignition when it is predicted.

(Means for Solving the Problems) In order to achieve the above object, an abnormal combustion detection device for an internal combustion engine according to the present invention comprises an ignition timing setting means for setting an ignition timing according to an operating state of the internal combustion engine, and When the vehicle is in a predetermined operating state where ignition can occur,
Ignition retarding means for retarding the ignition timing set by the ignition timing setting means by a predetermined amount, and abnormal combustion detecting means for detecting post-ignition of the engine when the ignition timing retarding means retards the ignition timing. And with.

Further, the combustion control device for an internal combustion engine of the present invention is provided with an in-cylinder temperature lowering means for lowering the in-cylinder temperature of the internal combustion engine when the abnormal combustion detecting means of the abnormal combustion detecting device detects abnormal combustion. .

(Operation) The abnormal combustion detection device configured as described above is configured to detect an abnormal combustion state (post ignition) that occurs prior to preignition in a normal engine operating state in an engine operating state where preignition may occur. I will retard the ignition timing at a predetermined angle below,
The possibility of pre-ignition is detected in advance by detecting whether abnormal combustion is occurring during the retard.

Further, the combustion control device lowers the in-cylinder temperature by the in-cylinder temperature lowering means when the possibility of preignition is detected.

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

FIG. 1 is a block diagram showing an overall configuration of an ignition timing control device to which an abnormal combustion detection device for an internal combustion engine and a combustion control device according to a first embodiment of the present invention are applied.

The ignition timing control device controls, for example, the ignition of the four-cylinder internal combustion engine 1, is mainly composed of the ignition timing control means 5, and operates the ignition plug 2 based on the ignition timing signal generated from the ignition timing control means 5. Spark ignition is performed.

The ignition timing control means 5 is attached to the engine, for example, around the cam shaft, and the top dead center (TD
C) Generate a TDC signal that represents the reference crank angle position of each cylinder at the previous predetermined crank angle position (eg, 10 ° BTDC) T
The DC sensor 6 is connected.

Furthermore intake air temperature is in the ignition timing control means 5 (T _A) intake air temperature sensor (T _A sensor) 71 for detecting the temperature of intake air (H _A)
Temperature sensor ( _HA sensor) 72 for detecting engine, knock sensor 73 for detecting engine knock condition, engine water temperature (Tw)
Is connected to a water temperature sensor (Tw sensor) 74 and other engine operation parameter sensor 75, and the output signals of these sensors 71 to 75 are supplied to the ignition timing control means 5. The ignition timing control means 5 determines the generation timing of the ignition timing signal based on the signals from the detection means 6 and various sensors 71 to 75 so as to obtain the ignition timing at which the operability and exhaust gas characteristics of the engine are optimized. To do.

Further, the sensors 71 to 74 are also electrically connected to the engine operating condition determination circuit 101 described later, and the determination circuit 101 based on the output signals of these sensors 71 to 74 will be described later in detail in post ignition and pre-ignition. Determine the engine operating conditions that are likely to occur.

The ignition timing control means 5 includes the engine operating condition determination circuit which constitutes an ignition retardation means 10 as described later in detail.
101, a specific ignition timing retarding circuit 102, and a set ignition timing retarding means as an in-cylinder temperature lowering means that operates when abnormal combustion in a cylinder is detected by an abnormal combustion detecting means 20 which will be described later and prevents preignition from occurring. The circuits 8 are connected to each other, and the ignition timing control means 5 outputs the ignition timing signals set according to the engine operating state according to the signals from the specific ignition timing retarding circuit 102 and the set ignition timing retarding circuit 8, respectively. circuit
It retards for a predetermined period determined by 102 and 8.

The ignition timing signal representing the ignition timing determined by the ignition timing control means 5 is supplied to the ignition unit 4 including a distributor and an ignition coil. A distributor (not shown) in the ignition unit 4 electrically connects the ignition plug 2 and the ignition coil of the cylinder to be ignited by the ignition timing signal, that is, the cylinder whose compression stroke has been completed, and is not shown in the ignition unit 4. The igniter energizes and discharges the ignition coil according to the ignition timing signal. Therefore, the ignition signal (FIG. 2 (a)) obtained by the discharge of the ignition coil is supplied to the cylinder to be ignited, and the spark ignition is performed.

A high-voltage diode 3 is arranged between the ignition plug 2 and the ignition unit 3, and the ignition plug 2 is operated by the operation of the high-voltage diode 3 so that the ignition voltage circuit A (a circuit including the ignition unit 4, the ignition plug 2 and the like). And a part of a combustion state circuit B (a circuit including a spark plug 2, a high voltage diode 3, and an ion current detection circuit 201) for detecting the combustion state of the air-fuel mixture in the cylinder. More specifically, the spark plug 2 is configured as an ignition part of an ignition voltage circuit A for performing spark ignition as described in JP-A-55-75629, and a combustion state for detecting a combustion state in a cylinder. It is configured as an ion current detection unit of the detection circuit B. The combustion state detection circuit B is a combustion state detection device focusing on the fact that when the combustion of the air-fuel mixture in the cylinder occurs, an ion flow is generated between the electrodes of the ignition plug 2 due to the combustion. Therefore, if a predetermined voltage is applied in advance between the electrodes of the spark plug by the battery (not shown) of the combustion state detection circuit B, an ionic current is generated in the detection circuit B when the air-fuel mixture in the cylinder burns, The combustion state of the air-fuel mixture in the cylinder can be detected by detecting this ion current. When the high voltage from the ignition unit 4 is supplied to the spark plug 2, the high voltage diode 3 prevents the high voltage from flowing to the combustion state detection circuit B side, and the spark plug 2 has two functions (ignition voltage circuit). The function of A as an ignition part and the function of an ion current detection part of the combustion state detection circuit B). Therefore, the ignition plug 2 acts as an ignition part of the ignition voltage circuit A when a high voltage (ignition signal) is generated from the ignition unit 4, and as an ion current detection part of the combustion state detection circuit B when a high voltage is not generated. To work.

The ionic current representing the combustion of the air-fuel mixture, which is detected by the spark plug 2, is supplied to the abnormal combustion detection means 20 including the ionic current detection circuit 201 and the post-ignition determination circuit 202 via the high voltage diode 3.

Next, the operation of the ignition timing retarding means 10 and the abnormal combustion detecting means 20 of the ignition timing control device configured as described above will be described below.
It will be described with reference to the drawings.

As described above, in the hot surface ignition, which is the abnormal combustion of the internal combustion engine, the post ignition, in which the abnormal ignition starts after the ignition timing of the normal spark ignition by the spark plug 2, and the normal spark of the normal ignition timing before flying. It is generally known that there is a preignition at which abnormal ignition starts, and before ignition due to preignition occurs, abnormal ignition due to post ignition always occurs, and thereafter the abnormal ignition time gradually advances to preignition. ing. Therefore, in the present invention, when the predetermined engine operating conditions (high intake temperature, specific temperature condition, high water temperature, etc.) that may cause preignition are established by the ignition retarding means 10, the engine is specified. Cylinder (eg # 3
(Cylinder) ignition timing is retarded by a certain angle so as not to significantly affect the engine operating state, and the ignition signal generation timing is set after the post-ignition generation timing that occurs before reaching the pre-ignition, and abnormal combustion detection means It is possible to detect the post-ignition occurrence state by 20.

The abnormal combustion detection means 20 detects the mixture in the cylinder due to post ignition before the ignition timing retarded by the ignition retardation means 10 (the ignition signal generation timing t ₂ ′ of the # 3 cylinder in FIG. 2B). Whether or not combustion actually occurs is determined, and the risk of pre-ignition occurrence is determined according to the frequency of post-ignition occurrence.

More specifically, the engine operating condition determination circuit 101 in the ignition retarding means 10 is a predetermined engine that is prone to preignition based on output signals from the various parameter sensors 71 to 75 that detect the engine operating state. Determine if operating conditions are met. The predetermined operating conditions include that the engine intake air temperature (T _A ) is equal to or higher than a predetermined high intake air temperature, the intake air temperature (H _A ) is within a specific temperature range in which high engine output is obtained, and the engine water temperature ( Tw) is higher than a predetermined high water temperature, and the knock sensor causes a predetermined knock (light knock) that does not damage the engine.

Based on the output signals of the above-mentioned various sensors 71 to 75, the engine operating condition determination circuit 101 is at least 1 above.
When it is determined that one of the operating conditions is satisfied, a signal indicating that the predetermined operating condition is satisfied is supplied from the engine operating condition determining circuit 101 to the specific ignition timing retarding circuit 102. The specific ignition timing retarding circuit 102 ignites the specific cylinder (# 3 cylinder) to the extent that the engine operating state is not significantly affected when the predetermined operating condition is satisfied based on the signal from the engine operating condition determining circuit 101. A signal for retarding the timing by a fixed angle is supplied to the ignition timing control means 5. On the other hand, the specific ignition timing retarding circuit 102 outputs a signal indicating that the ignition timing of the specific cylinder is retarded in order to detect the post-ignition before the pre-ignition, to the abnormal combustion detection means.
It is supplied to the ion current detection circuit 201 in 20.

The ignition timing control means 5 receiving the signal from the specific ignition timing retarding circuit 102 generates an ignition timing signal by delaying only the ignition timing of the specific cylinder (# 3 cylinder) by a fixed angle and supplies it to the ignition unit 4. To do. Therefore, the ignition unit 4 generates an ignition signal shown in FIG. 2B, and this ignition signal is supplied to the ignition plug 2.

Now, suppose that the post-ignition (hot surface ignition) occurs in the cylinder when the predetermined operating condition is satisfied. Since the generation timing of the post ignition is after the ignition timing of the spark plug 2, the generation state thereof cannot be detected from the beginning, but as shown in FIG. 2 (b), the ignition timing of the specific cylinder (# 3 cylinder) is changed. fixed angle retarded to the postignition generation timing (FIG. 2 (c)) is pre-ignition timing by the spark plug 2 after retarded (Figure 2 (b) t ₂ 'time).

Therefore, the ion current waveform due to the occurrence of the post ignition shown in FIG. 2 (c) appears when the ignition plug 2 acts as the ion current detection portion of the combustion state detection circuit B, and further, the ignition plug 2 It can be concluded that the combustion in the cylinder that occurs before ignition is due to post ignition.

The ion current flowing in the combustion state detection circuit B via the ignition plug 2 is sent to the ion current detection circuit 201. The ion current detection circuit 201 detects from the signal from the specific ignition timing retarding circuit 102 that the predetermined operating condition is satisfied, and the ion current generated while the predetermined operating condition is satisfied. Is supplied to the post-ignition determination circuit 202 as a signal indicating the post-ignition occurrence state. The post-ignition determination circuit 202 detects how many times the signal representing the generation of the ion current from the ion current circuit 201 has occurred while the predetermined operating conditions are satisfied, and the signal representing the generation of the ion current. Is detected for a predetermined number of times or more, it is determined that there is a risk of preignition occurrence (the possibility of the preignition occurring due to the advance of the currently occurring postignition occurrence timing). At this time, the post ignition determination circuit 20
2 is a signal indicating the possibility of pre-ignition occurrence,
It is supplied to a set ignition timing retarding circuit 8 as a cylinder temperature lowering means. Based on the signal from the post-ignition determination circuit 202, the set ignition timing retarding circuit 8 retards the ignition timing signals of all cylinders set according to the engine operating condition for a predetermined period in order to avoid pre-ignition. A signal is supplied to the ignition timing control means 5. In this case, the retarding of the predetermined angle is performed for a predetermined time, and after the predetermined time has elapsed, the retarded ignition timing signal is gradually returned to the advance side to obtain a normal value (ignition timing suitable for the engine operating state). When the post-ignition occurs again, the synchronization retard control is repeated. As a result, when the post ignition occurs, the ignition timings of all the cylinders are retarded by a predetermined angle, the combustion temperature of the air-fuel mixture is lowered, and the temperatures of the inner wall of the cylinder, the ignition plug, etc. are also lowered, which may occur following the post ignition. You can surely avoid play ignition.

FIG. 3 shows a second embodiment of the present invention, in which the combustion state detection circuit B of the first embodiment (spark plug 2, high voltage diode 3,
Instead of the ion current detection circuit 201), a combustion state detection device is provided with a combustion light detection circuit 201 (optical scope) B1, a combustion detection circuit 20.
It is composed of 1B. More specifically an optical scope
B1 has its tip B1a reaching the combustion chamber 1b in the cylinder,
Further, the tip portion B1a is inserted and inserted through the cylinder head 1a so that the tip portion B1a is directed to a portion in the combustion chamber 1b where abnormal combustion occurs (in the vicinity of the tip of the plug 2 which is the nucleus of abnormal combustion). The optical scope B1 optically detects a flame associated with combustion in the combustion chamber 1b, and a signal indicating the occurrence of the flame is a combustion detection circuit.
Sent to 201B. The combustion detection circuit 201B cooperates with the post-ignition determination circuit 202 to form an abnormal combustion detection means 20 ', and the circuit 201B is a specific ignition timing retarding circuit similar to the ion current detection circuit 201 of the first embodiment. While receiving the signal from 102 indicating that the ignition timing of the specific cylinder (# 3 cylinder) has been retarded by a certain angle (while the above-mentioned predetermined operating condition where post ignition is likely to occur is satisfied). A signal indicating the flame generation timing detected by the scope B1 is supplied to the post-ignition determination circuit 202B. The determination circuit 202B estimates the timing at which a regular flame is generated by spark ignition based on the ignition timing signal from the ignition timing control means 5, and the timing at which the flame detected by the optical scope B1 is generated is the regular flame generation. It is determined whether it was earlier than the timing. By this determination, the post-ignition determination circuit 202, when it is determined that the detected actual flame generation timing is earlier than the regular flame generation timing after advancing the fixed angle, the detected flame is generated by the post-ignition. When it is determined that the combustion is abnormal, a signal indicating the possibility of preignition occurrence is supplied to the set ignition timing retarding circuit 8 as the cylinder temperature lowering means.

Since the other structure and operation of the second embodiment are the same as those of the first embodiment described above, the same symbols are attached to the drawings and the description thereof is omitted.

FIG. 4 shows a third embodiment of the present invention, in which the combustion state detecting device (spark plug, high voltage diode 3,
Ion current detection circuit 201; Optical scope B1, Combustion detection circuit 201
Instead of B), a rotation speed change degree detection circuit 201c that detects a change state of the engine rotation speed is provided, and abnormal combustion in the combustion chamber is estimated based on the rotation speed change degree detected by the circuit 201c. It is a thing.

As described above, when it is determined that the predetermined operating condition is satisfied based on the output signals of the various sensors 71 to 75, the operation of the specific ignition timing retarding circuit 102 causes the ignition timing of the specific cylinder to be retarded by a certain angle. . When the ignition timing is retarded by a certain angle in this way, the engine output decreases and the engine speed (Ne) fluctuates. However, if post ignition occurs in a cylinder that is retarded by a certain angle, it will occur earlier than the retarded timing. Since the flame is generated in the combustion chamber, the fluctuation range (degree of decrease) of the engine speed (Ne) becomes small. The third embodiment utilizes such characteristics.

The rotation speed change degree detection circuit 201c constitutes the abnormal combustion detection means 20 ″ in cooperation with the post ignition determination circuit 202c, and the circuit 201c makes the ignition timing of the specific cylinder from the specific ignition timing retarding circuit 102 constant. Degree of change in engine speed (We) when a signal indicating that the angle is retarded is received −
Post-ignition determination circuit for the signal representing (ΔNe)
Supply to 202c. The determination circuit 202c determines whether or not the change degree (ΔNe) is smaller than a predetermined width, and when it is determined that the change degree (ΔNe) is smaller than the predetermined width, it is determined that abnormal combustion due to post ignition has occurred. Then, a signal indicating the possibility of preignition is supplied to the set ignition timing retarding circuit 8 as the cylinder temperature lowering means.

Since the other characteristics and actions of the third embodiment are the same as those of the first embodiment described above, the same reference numerals are given to the drawings and the description thereof will be omitted.

In the above-described third embodiment, the abnormal combustion inside the combustion chamber is estimated by the degree of change of the engine speed (Ne) without directly detecting it. However, there is a similar method for estimating the abnormal combustion as follows.

First, a torque sensor (for example, a sensor that detects the distortion of the crankshaft using a moire fringe) is provided on the crankshaft of the engine, and the ignition timing is retarded when the predetermined operating condition is satisfied. A method of determining whether or not the engine output has decreased and the shaft torque has changed can be considered. From this determination, it is possible to presume that abnormal combustion due to post-ignition has occurred when the fluctuation of the shaft torque is small despite the retardation of the ignition timing.

Secondly, an in-cylinder acupressure sensor is provided in the combustion chamber of the engine,
This is a method of detecting abnormal combustion in the combustion chamber based on the output of the in-cylinder acupressure sensor. The cylinder pressure finger pressure sensor detects a pressure in the combustion chamber by a piezoelectric element provided at a washer of an ignition plug, for example, and the ignition timing is retarded by a constant angle when the predetermined operating condition is satisfied. It can be estimated that the post-ignition has occurred when the pressure fluctuation due to combustion is detected by the in-cylinder finger pressure sensor before the retarded ignition timing.

Therefore, even if the abnormal combustion detection device and the combustion control device are configured by using a combustion state detection device including a torque sensor or a cylinder pressure finger pressure sensor instead of the combustion state detection device of the first to third embodiments described above, the same is true. The effect of is obtained.

The means for avoiding pre-ignition is not limited to the means for retarding the ignition timing, but for example, the means for controlling the fuel supply excessively supplies the fuel and the heat of vaporization cools the inner wall of the cylinder and the like. It may be done.

Further, in each of the above embodiments, only the ignition timing of the single specific cylinder (# 3 cylinder) is retarded in order to detect abnormal combustion (post-ignition), but the ignition timing of a plurality of cylinders is not limited to this. Alternatively, the abnormal combustion may be cooled similarly.

(Effect of the Invention) Abnormality As described in detail, the abnormal combustion detection device for an internal combustion engine according to the present invention includes an ignition timing setting means for setting an ignition timing according to an operating state of the internal combustion engine, and a preignition of the engine. An ignition retarding means for retarding the ignition timing set by the ignition timing setting means by a predetermined amount when in a predetermined operating state, and a post of the engine when the ignition retarding means retards the ignition timing. Since it is equipped with abnormal combustion detection means for detecting the ignition, it is possible to detect the post-ignition occurrence state, which was previously undetectable, and to further detect the pre-ignition occurrence state based on the post-ignition occurrence state. The occurrence can be inferred. Further, since the combustion control device for the internal combustion engine of the present invention includes the in-cylinder temperature lowering means for lowering the in-cylinder temperature when the abnormal combustion detecting means of the anomaly detecting device detects an abnormal combustion, preignition occurs. It is possible to avoid the occurrence of the pre-ignition when is predicted.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an ignition timing control device to which an abnormal combustion detection device for an internal combustion engine and a combustion control device according to a first embodiment of the present invention are applied, and FIG. 2 is an ignition timing shown in FIG. For explaining the relationship between the ignition signal obtained by the control means according to the engine operating state, the ignition signal retarded by the action of the specific ignition timing retarding circuit, and the waveform of the ion current representing the occurrence of the post ignition. 3 is a timing chart, FIG. 3 is a block diagram showing the overall configuration of the ignition timing control device according to the second embodiment of the present invention, and FIG. 4 is the overall configuration of the ignition timing control device according to the third embodiment of the present invention. It is a block diagram. 1 ... Internal combustion engine, 2 ... Spark plug, 5 ... Ignition timing control means, 8 ... Set ignition timing retarding circuit, 10 ... Ignition retarding means, 20, 20 ', 20 "... Abnormal combustion detection means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02P 5/153

Claims (11)

[Claims] 1. An ignition timing setting means for setting an ignition timing according to an operating state of an internal combustion engine, and an ignition timing set by the ignition timing setting means when the engine is in a predetermined operating state in which preignition can occur. An internal combustion engine comprising: an ignition retarding means for retarding a timing by a predetermined amount; and an abnormal combustion detecting means for detecting a post-ignition of the engine when the ignition retarding means retards the ignition timing. Engine abnormal combustion detection device. 2. An ignition timing setting means for setting an ignition timing according to an operating state of an internal combustion engine, an ignition retarding means for retarding the ignition timing set by the ignition timing setting means, and an ignition retarding means. An abnormal combustion detecting means for detecting an abnormal combustion state of the internal combustion engine when the ignition timing is retarded, and an in-cylinder temperature lowering means for decreasing the in-cylinder temperature when the abnormal combustion detecting means detects an abnormal combustion. A combustion control device for an internal combustion engine, comprising: 3. The combustion control system for an internal combustion engine according to claim 2, wherein the ignition retarding means includes an engine operating condition determination circuit which operates at a high engine temperature. 4. The combustion control system for an internal combustion engine according to claim 2, wherein the ignition retarding means includes an engine operating condition determination circuit which operates when a predetermined knock condition of the engine is detected. 5. The combustion control apparatus for an internal combustion engine according to claim 2, wherein the ignition retarding means retards only a specific cylinder, and the in-cylinder temperature lowering means operates simultaneously for all the cylinders. 6. The in-cylinder temperature lowering means comprises a set ignition timing retarding means for retarding the ignition timing by a predetermined angle.
6. The combustion control device for an internal combustion engine according to any one of 5 to 5. 7. The combustion control device for an internal combustion engine according to claim 2, wherein the abnormal combustion detection means comprises ion current detection means. 8. The combustion control device for an internal combustion engine according to claim 2, wherein the abnormal combustion detection means comprises a combustion light detection device. 9. The combustion control device for an internal combustion engine according to claim 2, wherein the abnormal combustion detection means comprises engine rotation fluctuation detection means. 10. The combustion control device for an internal combustion engine according to claim 2, wherein the abnormal combustion detection means comprises engine output shaft torque detection means. 11. The combustion control device for an internal combustion engine according to claim 2, wherein the abnormal combustion detection means comprises a cylinder pressure detection means.