JP2012137030A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine that determines the ignitability of fuel not limited to a region of a high load.SOLUTION: The device includes: a knocking detector 18 for detecting knocking; an ozone generator 23 for generating ozone supplied into a combustion chamber 11; and a controller 100 for controlling the internal combustion engine. The controller supplies the ozone generated by the ozone generator into the combustion chamber 11, and determines the ignitability of fuel of the internal combustion engine according to an output of knocking which are detected by the knocking detector in the combustion caused by combustion spark ignition combustion.

Description

  The present invention relates to a control device for an internal combustion engine.

  An engine system that drives a mechanical device, includes an ignition means for spark-igniting a cylinder and fuel in the cylinder, and includes compression self-ignition combustion (hereinafter also referred to as HCCI (Homogeneous-Charge Compression Ignition) combustion) and spark ignition. An engine that performs combustion (hereinafter also referred to as SI (Spark Ignition) combustion), self-ignition detection means that detects self-ignition of fuel, operation information detection means that detects information related to the operating state of the mechanical device, and operating state Control means for controlling the engine so as to selectively perform self-ignition combustion and spark ignition combustion based on the information regarding the ignition timing when the engine is performing spark ignition combustion. The self-ignitability of the fuel is determined based on the ignition timing when the self-ignition detection means detects the self-ignition of the fuel. And, which set the specified range for spark ignition combustion based on self-ignitability is known (Patent Document 1).

JP 2007-107486 A

  However, in the above engine system, since the ignitability is determined in the high load region, there is a problem that the self-ignition property cannot be determined unless the engine is operated in the high load region.

  The problem to be solved by the present invention is to provide a control device for an internal combustion engine that can determine the ignitability of the fuel, not limited to a high load region.

  The present invention solves the above problem by detecting knocking in a state where ozone is supplied into a combustion chamber and combustion is performed by spark ignition combustion, and the ignitability of the fuel is determined according to the detection result.

  According to the present invention, by supplying ozone to the combustion chamber and performing spark ignition combustion, the ignitability of the fuel is increased. Therefore, the ignitability of the fuel can be determined not only in the high-load operation region.

It is a block diagram which shows the engine which concerns on one embodiment of this invention. It is a graph which shows the torque characteristic with respect to the engine speed in the engine of FIG. It is a graph which shows the characteristic of the knock sensor output value with respect to the ozone supply density | concentration in the engine of FIG. It is a graph which shows the ignitability characteristic with respect to the ozone supply density | concentration in the engine of FIG. In the graph showing the torque characteristics with respect to the engine rotation speed in the engine of FIG. 1, (a) shows an operation region where HCCI combustion is possible when the ignitability is highest, and (b) shows HCCI when the ignitability is second highest. FIG. 5C is a graph showing an operation region in which HCCI combustion is possible when the ignitability is lowest. It is a flowchart which shows the control procedure of the engine of FIG. 6 is a graph showing the characteristics of supply air amount with respect to ignition timing in an engine according to another embodiment of the present invention. It is a graph which shows the characteristic of the knock sensor output value with respect to ignition timing. It is a graph which shows the characteristic of ignitability with respect to a knock sensor output value. It is a flowchart which shows the control procedure of the engine which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is an overall configuration diagram of an engine to which an embodiment of the present invention is applied. The engine 1 includes a direct injection type gasoline engine main body 10 that directly injects fuel into the combustion chamber 11. A throttle valve 21 and a collector 22 are sequentially arranged in the intake passage 20 of the engine 1.

  A throttle motor (not shown) such as a DC motor for adjusting the opening degree of the throttle valve 21 is connected to the throttle valve 21. A throttle sensor (not shown) for detecting the opening degree of the throttle valve 21 is provided in the vicinity of the throttle valve 21. The throttle motor and the throttle sensor are respectively connected to an ECU 100 (Engine Control Unit), and the throttle valve 21 is operated by a control signal from the ECU 100.

  The intake passage 20 is branched by a collector 22, and an ozone generator 23 is provided at the branched end. The ozone generator 23 includes a discharger for generating plasma, a power source, and the like, and operates based on a control signal from the ECU 100. The ozone generator 23 generates ozone by causing low-temperature plasma generated in the discharger to act on the air taken into the discharger.

  The ozone generator 23 may generate ozone by, for example, a photochemical reaction method in which oxygen molecules are irradiated with ultraviolet rays, may generate ozone by an electrolytic method in which an aqueous solution of hydrochloric acid or sulfuric acid is electrolyzed, Ozone may be generated by a radiation irradiation method that irradiates molecules with radiation, or ozone is generated by causing a discharge in an oxygen-containing gas by a silent discharge method, a corona discharge method, a streamer discharge method, or a composite discharge method. It may be generated.

  The ozone generated by the ozone generator 23 is supplied into the combustion chamber 11 from the intake port 121 through the collector 22 on the downstream side of the throttle valve 21.

  The intake passage 20 communicates with the combustion chamber 11 of the engine body 10 via an intake port 121, and the intake port 121 can be opened and closed by an intake valve 122.

  The engine body 10 includes a cylinder 13, a piston 14, and a cylinder head (not shown) provided with an intake valve 122 and an exhaust valve 172, and the combustion chamber 11 is defined by these. Further, in the combustion chamber 11, the injection port of the fuel injection valve 15 and the tip of the spark plug 16 face each other. Further, the combustion chamber 11 communicates with the exhaust passage 30 via an exhaust port 171, and the exhaust port 171 can be opened and closed by an exhaust valve 172.

  The intake valve 122 and the exhaust valve 172 are provided with a valve operating mechanism (not shown) for opening and closing the valves 122 and 172. The valve operating mechanism is based on a control signal from the ECU 100. This is a mechanism that varies the valve timing by varying the phase and lift amount of each operating angle of the valve 172. As the valve operating mechanism, a cam switching mechanism, an energization mechanism using electromagnetic force, or the like is used.

  The fuel injection valve 15 injects fuel at a predetermined timing based on a control signal from the ECU 100, and the spark plug 16 performs spark ignition at a predetermined timing based on the control signal from the ECU 100.

  The engine body 10 includes a knock sensor 18. The knock sensor 18 is provided in the cylinder 13 and detects high-frequency vibration of the cylinder 13 due to knocking. Then, ECU 100 determines the presence or absence of knocking from the output value from knock sensor 18. When knocking has occurred, the ECU 100 controls the ignition plug 16 to adjust the ignition timing of the engine 1, controls the intake valve 122 and the exhaust valve 172, changes the valve timing, and knocks. Suppresses the occurrence of

  The ECU 100 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an interface, and the like. In this embodiment, spark ignition combustion (SI combustion) and compression self-ignition combustion (HCCI combustion). Control to switch between and.

  Specifically, in SI combustion, the fuel injection valve 15 is driven at a predetermined timing to inject a predetermined amount of fuel into the combustion chamber 11, and the fuel generated in the combustion chamber 11 and the intake air are used as fuel. Then, spark ignition combustion is performed by the spark plug 16. At this time, the ECU 100 adjusts the torque generated by the engine 1 by controlling the opening degree of the throttle valve 21 and the fuel injection amount from the fuel injection valve 16, and controls the spark plug 16 to ignite the fuel. Let

  On the other hand, in HCCI combustion, the throttle valve 21 and the fuel injection valve 16 are controlled, but the ignition plug is not controlled because the fuel is self-ignited.

  Further, the ECU 100 determines switching between SI combustion and HCCI combustion based on, for example, the engine rotation speed and the engine load. Specifically, the ECU 100 reads the engine rotation speed based on a detection signal from a crank angle sensor (not shown), and reads the accelerator opening (depressing amount of the accelerator pedal) from an accelerator sensor (not shown). It is determined whether the operation point detected by the above is in the operation region where SI combustion is possible or in the operation region where HCCI combustion is possible.

  Further, as will be described later, the ECU 100 sets an operation region in which HCCI combustion is possible according to the ignitability (octane number) of the fuel. In order to determine the ignitability of the fuel, the ECU 100 detects ozone in the combustion chamber 11 when the rotational speed of the engine 1 is low to medium and when the load of the engine 1 is low to medium. And spark ignition combustion. Then, ECU 100 determines the ignitability of the fuel from the output value of knock sensor 18.

  Hereinafter, the control contents for determining the ignitability in the ECU 100 will be described with reference to FIGS. 2 is a graph showing engine torque characteristics with respect to engine rotation speed, FIG. 3 is a graph showing characteristics of knock sensor output values with respect to ozone supply concentration, and FIG. 4 is a graph showing ignitability characteristics with respect to ozone supply concentration. It is a graph. In FIG. 2, the graph P shows the torque characteristics in the high load region in the engine 1 of this example, and the region Q shows the ignitability determination region. In FIG. 3, graph A shows the characteristic when the ignitability is the highest, graph B shows the characteristic when the ignitability is the second highest, and graph C shows the characteristic when the ignitability is the lowest.

First, the ECU 100 reads the accelerator opening and the engine rotation speed, and determines whether or not the operating point is included in the ignitability determination region. The ignitability determination region indicates an operation region for determining the ignitability of the fuel, and is represented by a range indicated by the rotation speed and torque of the engine 1 as in a region Q of FIG. In this example, the engine speed is between ω ₁ and ω ₂ and the torque is between T ₁ and T ₂ as the ignitability determination region. Further, ω ₁ and ω ₂ are rotation speeds set in advance, and the rotation speed range indicated by ω ₁ to ω ₂ corresponds to low rotation to medium rotation among the rotation speeds that the engine 1 can take. To do. The torque range indicated by T ₂ from T ₁ is in a torque that can be taken in the engine 1, it corresponds to the medium torque from a low torque.

  If the operating point is included in the ignitability determination region, the ECU 100 controls the spark plug 16 while driving the ozone generator 23 to supply ozone into the combustion chamber 11 and spark ignition combustion. Let it knock. Normally, knocking occurs in the high load region in the vicinity shown by the graph P in FIG. 2. However, since the ignition determination region in this example is a low load operation region, knocking occurs even if spark ignition combustion is performed in this region Q. It is hard to do. However, in this example, since ozone is supplied into the combustion chamber 11 in the ignitability determination region Q, it is easy to knock, and the knocking detection sensitivity is increased.

  During the spark ignition combustion while supplying ozone into the combustion chamber 11, the knock sensor 18 detects the vibration of the knocking frequency of the engine 1 and outputs a detection signal to the ECU 100. The ozone generator 23 gradually increases the amount of ozone generated during spark ignition combustion, and gradually increases the supply concentration of ozone supplied into the combustion chamber.

Then, ECU 100 determines that knocking has occurred when the output signal of the detection signal is higher than a predetermined threshold (Kc), and determines the ignitability of fuel from the ozone supply concentration at the time of occurrence of knocking. Here, the threshold value (Kc) is a threshold value for determining knocking, and is a preset value. As shown in FIG. 3, the output value of knock sensor 18 increases in proportion to the ozone supply concentration. In graph A, the output value of knock sensor ozone supply concentration at the time of d ₁ reaches Kc, In graph B, the output value of knock sensor ozone supply concentration at higher d ₂ than d ₁ reaches Kc, in graph C, the ozone feed concentration is the output value of knock sensor reaches Kc at higher d ₃ than d _2. When the fuel ignitability is high, knocking occurs when the ozone supply concentration is low. Conversely, when the fuel ignitability is low, knocking does not occur unless the ozone supply concentration is high. Therefore, as shown in FIG. 4, the ozone supply concentration and the ignitability are in a directly proportional relationship with a negative coefficient, and the point A (at point a on the graph A in FIG. 3) where knocking occurred at the ozone supply concentration (d ₁ ). The point B (corresponding to point b on the graph B in FIG. 3) where knocking occurred at the ozone supply concentration (d ₂ ) is the second highest, and the ozone supply concentration (d ₃ ) The ignitability at the point C (corresponding to the point c on the graph C in FIG. ₃ ) where knocking occurred is the lowest.

  Thus, the ECU 100 performs spark ignition combustion while supplying ozone into the combustion chamber 11, and determines the ignitability of the fuel from the output of the knock sensor.

  Next, the operation region set by the ECU 100 and capable of HCCI combustion will be described with reference to FIG. FIG. 5 is a characteristic diagram showing an operating region in which HCCI combustion is possible (shown by hatching in the same figure) in the torque characteristic with respect to the engine rotation speed, and (a) is a characteristic diagram when the ignitability is highest ( b) shows a characteristic diagram in the case of the second highest ignitability, and (c) shows a characteristic diagram in the case of the lowest ignitability.

  The ECU 100 sets an operation region that can be operated by compression self-ignition combustion (HCCI) according to the ignitability of the fuel. The operating region in which HCCI combustion is possible is indicated by the engine speed and torque, and the size of the operating region is determined by the ignitability of the fuel. That is, when the fuel ignitability is high, the combustion chamber 10 is in a state where it is easy to self-ignite. Therefore, the operating range in which HCCI combustion can be performed with respect to the engine speed and torque is reduced to the low load, low rotation side. Can be taken widely. On the other hand, when the ignitability of the fuel is low, the combustion chamber 10 is difficult to self-ignite, so the operating range in which HCCI combustion can be performed with respect to the engine speed and torque is reduced to the low load, low rotation side. The operating region where HCCI combustion is not possible is a narrow region on the high load side. Therefore, the ECU 100 sets a wider operation region in which HCCI combustion is possible as the ignitability increases.

  Next, the control procedure of this example will be described with reference to FIG. FIG. 6 is a flowchart showing the control procedure of this example.

  After the engine 1 is started, in step S10, the ECU 100 detects the rotational speed and target torque value of the engine 1 from a crank angle sensor (not shown) and an accelerator sensor (not shown), and detects the current operating point. To do.

  In step S20, ECU 100 determines whether or not the operating point in step S10 is included in a preset ignitability determination region. If the operating point is not included in the ignitability determination region, the process returns to step S10. On the other hand, when the operating point is included in the ignitability determination region, the process proceeds to step S30.

  In step S30, the ECU 100 turns on the ozone generator 23. In step S31, knock sensor 18 detects knocking and outputs a detected value to ECU 100.

  In step S32, ECU 100 determines whether or not the output value of the signal transmitted from knock sensor 18 is equal to or greater than a threshold value (Kc). If the output value of knock sensor 18 is equal to or greater than the threshold value (Kc), the process proceeds to step S34. On the other hand, when the output value of the knock sensor 18 is lower than the threshold value (Kc), the ECU 100 controls the ozone generator 23 to increase the output of the ozone generator 23 in step S33, and then the step S31. Return to. Thereby, when the output value of the knock sensor 18 is lower than the threshold value (Kc), the ECU 100 again determines the presence or absence of knocking after increasing the ozone supply concentration into the combustion chamber 10. Note that the output of the ozone generator 23 can be changed in stages, and the ECU 100 may increase the output level of the ozone generator 23 by one in step S33.

  In step S34, ECU 100 determines the ignitability of the fuel using the relationship shown in FIGS. 3 and 4 from the ozone supply concentration at the time when the output value of knock sensor 18 reaches the threshold value (Kc).

  In step S50, based on the ignitability in step S34, an operation region in which HCCI operation is possible is set using the relationship shown in FIG.

  In step S60, ECU 100 determines whether or not the motion point is within an operation region where HCCI operation is possible. In addition, what is necessary is just to detect the said operating point similarly to control of step S10.

  If the motion point is within the operating range where HCCI operation is possible, the valve timing is controlled to switch from spark ignition combustion to compression self-ignition combustion (step S70). When the intake passage 20 is provided with a supercharger (not shown), the ECU 100 also controls the target supercharging pressure of the supercharger. On the other hand, when the motion point is not within the operating range in which HCCI operation is possible, ECU 100 continues to perform spark ignition combustion without switching to compression self-ignition combustion (step S80). In step S80, when the spark ignition combustion is continuously performed, the ECU 100 may turn off the ozone generator 23.

  As described above, the present invention includes the knock sensor 18, the ozone generator 23, and the ECU 100, and supplies the ozone into the combustion chamber 10 to perform knocking by the knock sensor 18 in a state where spark ignition combustion is performed. Detecting and determining the ignitability of the fuel according to the output of the knock sensor 18. Thereby, since the ignitability of the fuel can be determined in a low rotation and low load state, the ignitability of the fuel can be determined earlier after the engine 1 is started. Moreover, since the detection sensitivity of knocking can be increased by supplying ozone into the combustion chamber 11 during the spark combustion, it is possible to improve the determination accuracy of the ignitability. Furthermore, in this example, since the determination accuracy of ignitability increases, misfire in the case of compression self-ignition combustion can be suppressed.

  Further, in this example, the ignitability determination region is set to a region between a low rotation and a middle rotation with a low load, so a high rotation and high load region where a mechanical load acts on the engine itself. Therefore, it is not necessary to cause knocking, so that adverse effects on parts such as the engine 1 and the load applied to the engine 1 can be minimized.

  Further, when the ignitability is determined in the high load and high rotation area as in the conventional case, the ignitability cannot be determined until the engine 1 is operated in the high load and high rotation area. After starting 1, the ignitability could not be determined early. Further, for example, in the traveling pattern such as JC08 mode defined by the Ministry of Land, Infrastructure, Transport and Tourism, the engine 1 is not operated in a high load and high rotation region. The ignitability could not be determined.

  In this example, since the ignitability is determined in a region between the low rotation and the middle rotation at a low load, the ignitability can be determined even in a traveling pattern such as the JC08 mode. Since it is possible to switch to combustion, JC08 mode fuel efficiency can be improved.

  Further, in this example, an operation region that can be operated by compression self-ignition combustion is set according to the determination result of the ignitability. Thereby, since the compression self-ignition combustion can be performed earlier after the engine 1 is started, the fuel consumption can be improved. Furthermore, since this example has high ignitability determination accuracy, the determination result of ignitability can be used when setting the operation region of compression self-ignition combustion, and as a result, fuel efficiency can be improved. .

  In this example, the ignitability is determined from the ozone supply concentration at the time when the output value of the knock sensor 18 reaches the threshold (Kc), but from the time when ozone is generated by the ozone generator 23, The ignitability may be determined from the length of time until the output value reaches the threshold value (Kc). That is, when ozone is generated by the ozone generator 23 and the ozone supply concentration is gradually increased, when the ignitability of the fuel is high, the output value of the knock sensor 18 is set to the threshold value (Kc) in a short time after the ozone is generated. ) And the ignitability of the fuel is low, the output value of the knock sensor 18 reaches the threshold value (Kc) in a long time after ozone is generated. Therefore, in this example, the ignitability may be determined according to the ozone supply time.

  The knock sensor 18 of this example corresponds to “knocking detection means” of the present invention, the ozone generator 23 corresponds to “ozone generation means”, and the ECU 100 corresponds to “control means”.

<< Second Embodiment >>
Next, a control device for the engine 1 according to another embodiment of the invention will be described. This example is different from the above-described first embodiment in that the ignitability is determined by making the amount of ozone generated from the ozone generator 23 constant and by advancing the ignition timing. About control other than this, description of 1st Embodiment is used suitably.

  FIG. 7 is a graph showing the characteristic of the supply air amount with respect to the ignition timing, and FIG. 8 is a graph showing the characteristic of the output value of the knock sensor 18 with respect to the ignition timing. In FIG. 8, graph A shows the characteristics when the ozone generator 23 is turned on (an example of the present invention), and graph B shows the characteristics when the ozone generator 23 is turned off (a comparative example of the present invention). ). FIG. 9 is a graph showing the ignitability characteristics with respect to the output of the knock sensor 18.

  The ECU 100 supplies ozone into the combustion chamber 11 while keeping the amount of ozone generated by the ozone generator 23 constant. The ECU 100 advances the ignition timing of the spark plug 16 and controls the throttle valve 21 to adjust the amount of air supplied to the engine 1 while spark ignition is performed.

  Here, the relationship between the ignition timing and the supply air amount and the relationship between the ignition timing and the output value of the knock sensor 18 will be described with reference to FIGS. In order to advance or retard the ignition timing from the normal ignition timing, the ECU 100 increases the supply air amount for spark ignition combustion, and the characteristics of the supply air amount with respect to the ignition timing are as shown in FIG. The spark plug 16 and the throttle valve 21 are controlled so as to have a minimum point at a normal ignition timing.

  As shown in FIG. 8, when the ignition timing is advanced, the output of the knock sensor 18 at the time of spark ignition combustion increases. Then, when ozone is supplied as in this example and A is not supplied as in the comparative example B, the slope of the output of the knock sensor 18 with respect to the ignition timing of this example A is the comparative example. It can be seen that it is significantly larger than B. That is, when ozone is supplied, the detection sensitivity of the knock sensor 18 increases. Thereby, by supplying ozone into the combustion chamber 11, the output value of the knock sensor 18 is increased, and the detection accuracy of knocking can be increased. Further, by supplying ozone into the combustion chamber 11 and advancing the ignition timing, the output value of the knock sensor is further increased, so that the knocking detection accuracy can be increased.

  As described above, the ECU 100 supplies a constant amount of ozone into the combustion chamber 11 and advances the ignition timing by a predetermined angle in a state where spark ignition combustion is performed, and from the output value of the knock sensor 18. Determine ignitability. As shown in FIG. 9, since the ignitability of the fuel is proportional to the output value of the knock sensor, the ECU 100 determines that the higher the output value of the knock sensor, the higher the ignitability of the fuel.

  Next, the control procedure of this example will be described with reference to FIG. FIG. 10 is a flowchart showing the control procedure of this example. In addition, since control of step S10, step S20, and step S50-S80 is the same content as control of step S10, step S20, and step S50-S80 of 1st Embodiment, description is abbreviate | omitted.

  In step S <b> 40, the ECU 100 turns on the ozone generator 23 and supplies a certain amount of ozone into the combustion chamber 11. In step S41, the ECU 100 controls the spark plug 16 to advance the ignition timing by a predetermined angle. The predetermined angle is a preset angle. As described above, since the detection sensitivity of the knock sensor 18 is increased by advancing the ignition timing, how much the output value of the knock sensor 18 is increased with respect to the normal ignition timing is determined at the time of design. The predetermined angle is set according to the above.

  In step S42, knock sensor 18 detects knocking and outputs a detection value to ECU 100. In step S43, ECU 100 determines the ignitability of the fuel according to the magnitude of the output value of the signal transmitted from knock sensor 18. That is, the ECU 100 determines that the fuel ignitability is high when the output value is high, and determines that the fuel ignitability is low when the output value is low.

  As described above, the present invention includes the knock sensor 18, the ozone generator 23, and the ECU 100, supplies a constant amount of ozone into the combustion chamber 10, and in a state where spark ignition combustion is performed, Is detected, and the ignitability of the fuel is determined according to the output of the knock sensor 18. As a result, the ignitability of the fuel can be determined earlier after the engine 1 is started, and the detection sensitivity of the knock sensor can be increased. As a result, the accuracy of determining the ignitability can be increased. Furthermore, misfire in the case of compression self-ignition combustion can be suppressed.

  Further, in this example, in a state where ozone is supplied into the combustion chamber 10 and spark ignition combustion is performed, the ignition timing is changed from the normal ignition timing, and the ignitability of the fuel is increased according to the output of the knock sensor 18. judge. Thereby, since the detection sensitivity by the knock sensor 18 becomes high, the detection accuracy of knocking can be increased, and the determination accuracy of ignitability can be increased.

  In this example, the ignition timing is advanced and the ignitability is determined from the output of the knock sensor 18, but the ignition timing is retarded and the ignitability is determined from the output of the knock sensor 18. Good. In this example, the ignition timing is advanced and the ignitability is determined from the output of the knock sensor 18, but the ignition timing is not necessarily advanced or retarded. That is, ECU 100 may determine the ignitability from the output value of knock sensor 18 without performing the control of step S41 of FIG.

DESCRIPTION OF SYMBOLS 1 ... Engine 10 ... Engine main body 11 ... Combustion chamber 121 ... Intake port 122 ... Intake valve 13 ... Cylinder 14 ... Piston 15 ... Fuel injection valve 16 ... Spark plug 171 ... Exhaust port 172 ... Exhaust valve 18 ... Knock sensor 20 ... Intake passage 21 ... Throttle valve 22 ... Collector 23 ... Ozone generator 30 ... Exhaust passage 100 ... ECU

Claims (5)

Knocking detection means for detecting knocking;
Ozone generating means for generating ozone supplied into the combustion chamber;
Control means for controlling the internal combustion engine,
The control means includes
In a state where ozone generated by the ozone generating means is supplied into the combustion chamber and burned by spark ignition combustion, the ignitability of the fuel of the internal combustion engine is determined according to the knocking output detected by the knocking detecting means. A control device for an internal combustion engine. The control means includes
2. The control apparatus for an internal combustion engine according to claim 1, wherein the higher the knocking output value detected by the knocking detection means, the higher the ignitability is determined. The control means includes
The knocking detection means detects knocking while gradually increasing the amount of ozone by the ozone generation means, and determines the ignitability according to the output of the knocking with respect to the amount of ozone. Item 3. The control device for an internal combustion engine according to Item 1 or 2. The control means includes
3. The internal combustion engine according to claim 1, wherein knocking is detected by the knocking detection means while the ignition timing is advanced, and the ignitability is determined according to an output of the knocking with respect to the ignition timing. Control device. The internal combustion engine is operated by switching between spark ignition combustion and compression self-ignition combustion,
The internal combustion engine according to any one of claims 1 to 4, wherein the control means sets an operation region operable by the compression self-ignition combustion in accordance with the determination result of the ignitability. Control device.

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