JP2013104298A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate a temperature rise in a piston when abnormal combustion occurs, regarding an internal combustion engine control device.SOLUTION: The internal combustion engine control device includes: a cylinder pressure information acquiring means for acquiring information on a cylinder when abnormal combustion occurs in an internal combustion engine 10; and a piston temperature increase estimation means for estimating a temperature increase of a piston 12 of the internal combustion engine 10 caused by the abnormal combustion based on the information acquired by the cylinder pressure information acquiring means. The piston temperature increase estimation means acquires a temperature increase width of the piston 12 in one abnormal combustion and summates the temperature increase width.It is determined whether abnormal combustion suppression control for suppressing the occurrence of the abnormal combustion should be performed based on an estimation result of the piston temperature increase estimation means.

Description

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

  In an internal combustion engine, abnormal combustion such as pre-ignition may occur. During abnormal combustion, the in-cylinder pressure becomes abnormally higher than during normal combustion, and the temperature of the piston rises.

  In Patent Document 1, when abnormal combustion is detected, as a control for suppressing the occurrence of abnormal combustion, a power transmission element of an automatic transmission connected to an internal combustion engine is controlled (sliding a frictional engagement element). Thus, a technique for performing control to increase the engine rotation speed is disclosed.

JP 2011-112115 A JP 2010-71284 A JP-A-9-273436 JP 2009-30545 A

  Other controls for suppressing abnormal combustion include control for injecting additional fuel into the cylinder and control for retarding the ignition timing. Regardless of which method is used to control abnormal combustion, it may affect any of fuel consumption, emission, drivability, etc., so it is not preferable to carry it out more than necessary. On the other hand, when fuel other than the specified fuel is used, such as low octane fuel, the temperature of the piston rises higher than expected in the design when abnormal combustion occurs, and control to suppress abnormal combustion starts. There is a risk that the piston temperature will rise above an acceptable limit before being done. In order to reliably protect the piston, it is desirable to accurately estimate the piston temperature under any conditions and prevent the piston temperature from exceeding an allowable limit.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a control device for an internal combustion engine that can accurately estimate a temperature rise of a piston when abnormal combustion occurs.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
In-cylinder pressure information acquisition means for acquiring information related to the in-cylinder pressure when abnormal combustion occurs in the internal combustion engine;
Piston temperature increase estimation means for estimating a temperature increase of the piston of the internal combustion engine due to the abnormal combustion based on the information acquired by the in-cylinder pressure information acquisition means;
It is characterized by providing.

The second invention is the first invention, wherein
The piston temperature rise estimating means is
Based on the information, a temperature increase width acquisition means for acquiring a temperature increase width of the piston per one time of the abnormal combustion;
Integrating means for integrating the temperature increase width acquired by the temperature increase width acquiring means when the abnormal combustion occurs continuously;
It is characterized by including.

The third invention is the first or second invention, wherein
The apparatus further comprises a determination unit that determines whether or not the abnormal combustion suppression control for suppressing the occurrence of the abnormal combustion is necessary based on the estimation result of the piston temperature increase estimation unit.

According to a fourth invention, in any one of the first to third inventions,
In-cylinder pressure detecting means for detecting the in-cylinder pressure of the internal combustion engine,
The in-cylinder pressure information acquisition unit acquires the information based on an output of the in-cylinder pressure detection unit.

According to a fifth invention, in any one of the first to fourth inventions,
The in-cylinder pressure information acquisition means acquires one or both of information relating to the amplitude of the in-cylinder pressure waveform during the abnormal combustion and information relating to the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during the abnormal combustion. It is characterized by doing.

According to a sixth invention, in any one of the first to fifth inventions,
The in-cylinder pressure information acquisition means includes means for acquiring information on the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during the abnormal combustion based on the operating state of the internal combustion engine. .

According to a seventh invention, in any one of the first to sixth inventions,
A fuel property judging means for judging the property of the fuel;
The in-cylinder pressure information acquisition means includes means for acquiring information relating to the amplitude of the in-cylinder pressure waveform during the abnormal combustion based on the fuel property determined by the fuel property determination means. It is characterized by.

  According to the first invention, it is possible to accurately estimate the temperature rise of the piston when abnormal combustion occurs regardless of conditions such as fuel properties and intake air temperature. For this reason, it becomes possible to cope appropriately before the temperature of the piston reaches the allowable limit.

  According to the second invention, it is possible to accurately estimate the temperature rise of the piston when abnormal combustion occurs continuously.

  According to the third invention, the abnormal combustion suppression control can be reliably executed before the piston temperature reaches the allowable limit, the piston can be reliably protected, and the abnormal combustion suppression control is executed more than necessary. Thus, the influence of the abnormal combustion suppression control on any of the fuel consumption, emission, drivability, etc. can be suppressed to the minimum.

  According to the fourth aspect, by measuring the in-cylinder pressure, information related to the in-cylinder pressure during abnormal combustion can be obtained with high accuracy.

  According to the fifth invention, by using one or both of information relating to the amplitude of the in-cylinder pressure waveform during abnormal combustion and information relating to the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during abnormal combustion. The temperature rise of the piston can be estimated with higher accuracy.

  According to the sixth invention, it is possible to obtain information on the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during abnormal combustion without using the in-cylinder pressure detecting means. The load can be reduced.

  According to the seventh aspect, since it is possible to acquire information related to the amplitude of the in-cylinder pressure waveform during abnormal combustion without using the in-cylinder pressure detecting means, it is possible to reduce the calculation load of the control device.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a graph which shows the change of the cylinder pressure in a compression stroke and an expansion stroke in the case of abnormal combustion and the case of normal combustion (normal combustion). It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a map for calculating the temperature rise width T of a piston. It is the map which defined the relationship between the kind of fuel, and the upper limit of cylinder pressure amplitude (DELTA) P at the time of abnormal combustion. 7 is a map that defines the relationship between the operating state (engine speed and torque) of an internal combustion engine and the upper limit value of the smoothed maximum in-cylinder pressure Pmax.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in FIG. 1, the system according to the first embodiment of the present invention includes a spark ignition type internal combustion engine 10. The number of cylinders and the cylinder arrangement of the internal combustion engine 10 are not particularly limited. In FIG. 1, only one cylinder is representatively depicted.

  Each cylinder of the internal combustion engine 10 is provided with a piston 12, an intake valve 14, an exhaust valve 16, a spark plug 18, and a fuel injector 20 that directly injects fuel into the cylinder (combustion chamber). .

  Each cylinder of the internal combustion engine 10 is connected to the intake passage 22 via an intake manifold (not shown). Each cylinder of the internal combustion engine 10 is connected to the exhaust passage 24 via an exhaust manifold (not shown).

  The internal combustion engine 10 of this embodiment has a turbocharger 26 as a supercharger. The turbocharger 26 has a compressor 26a and a turbine 26b. The compressor 26 a is arranged in the middle of the intake passage 22, and the turbine 26 b is arranged in the middle of the exhaust passage 24.

  An air cleaner 28 and an air flow meter 30 for detecting the amount of intake air are installed in the intake passage 22 upstream of the compressor 26a. An intercooler 32 and a throttle valve 34 are provided in the intake passage 22 on the downstream side of the compressor 26a.

  In the vicinity of the turbine 26b, a bypass passage 38 communicating the upstream exhaust passage 24 and the downstream exhaust passage 24 of the turbine 26b, and a bypass valve 40 (a waste gate valve) capable of opening and closing the bypass passage 38 are provided. And are installed. When the bypass valve 40 is opened, a part of the exhaust gas flows through the bypass passage 38 without passing through the turbine 26b. An exhaust purification catalyst 42 (catalytic converter) for purifying exhaust gas is installed in the exhaust passage 24 downstream of the turbine 26b.

  The system of the present embodiment includes a crank angle sensor 44 that detects the rotation angle of the crankshaft of the internal combustion engine 10, an in-cylinder pressure sensor 46 that detects in-cylinder pressure, an intake variable valve operating device 47 that drives the intake valve 14, An exhaust variable valve operating device 48 for driving the exhaust valve 16 and an ECU (Electronic Control Unit) 50 for controlling the operating state of the internal combustion engine 10 are further provided. The ECU 50 is electrically connected to the various sensors and actuators described above. The intake variable valve operating device 47 is configured to be able to change the opening / closing timing of the intake valve 14. The exhaust variable valve operating device 48 is configured to be able to change the opening / closing timing of the exhaust valve 16.

  The ECU 50 controls the operation of the internal combustion engine 10 by driving each actuator based on information detected by each sensor. For example, the fuel injection amount is calculated based on the engine speed (engine speed) detected by the crank angle sensor 44 and the intake air amount detected by the air flow meter 30, and the fuel injection timing based on the crank angle, After determining the ignition timing and the like, the fuel injector 20 and the spark plug 18 are driven.

  In the internal combustion engine 10, for example, abnormal combustion such as pre-ignition may occur. In abnormal combustion, the air-fuel mixture in the cylinder self-ignites before normal ignition timing (ignition by the ignition plug 18). Abnormal combustion tends to occur easily in a region where the engine speed is low and the engine load is high, that is, a low speed and high load region.

In the present embodiment, the ECU 50 can execute an operation capable of detecting the occurrence of abnormal combustion (hereinafter referred to as “abnormal combustion detection operation”) based on the in-cylinder pressure detected by the in-cylinder pressure sensor 46. Hereinafter, an example of the abnormal combustion detection operation will be described. The ECU 50 can calculate PV ^κ as a calorific value index value, where P is the in-cylinder pressure detected by the in-cylinder pressure sensor 46, V is the in-cylinder volume, and κ is the specific heat ratio of the in-cylinder gas. Note that the value of the in-cylinder volume V is a function of the crank angle θ and is stored in the ECU 50 in advance. The value of the specific heat ratio κ is also stored in the ECU 50 in advance. The value of PV ^κ correlates with the amount of heat generated in the cylinder. When the air-fuel mixture is ignited by abnormal combustion, heat is generated in the cylinder, and the value of PV ^κ increases. The ECU 50 repeatedly calculates the value of PV ^κ for each unit crank angle or for each unit time. When the calculated PV ^κ value exceeds a predetermined threshold value, it is determined that abnormal combustion has occurred. The ECU 50 can execute such an abnormal combustion detection operation for each cycle. In the present invention, the abnormal combustion detection operation is not limited to the operation using the in-cylinder pressure sensor 46. For example, the abnormal combustion is detected by detecting the ionic current flowing between the electrodes of the spark plug. It may be.

  FIG. 2 is a graph showing changes in in-cylinder pressure in the compression stroke and the expansion stroke in the case of abnormal combustion and in the case of normal combustion (normal combustion). In the example shown in FIG. 2, the ignition timing is after the compression top dead center. For this reason, in the case of normal combustion, after the compression top dead center is passed and the in-cylinder pressure starts to decrease, combustion starts and the in-cylinder pressure rises again. On the other hand, in the case of abnormal combustion, the in-cylinder pressure rises before the ignition timing, becomes higher than the maximum in-cylinder pressure during normal combustion, and the in-cylinder pressure greatly oscillates at a high frequency. In the following, as shown in FIG. 2, the amplitude (maximum amplitude) of the in-cylinder pressure waveform at the time of abnormal combustion is referred to as “in-cylinder pressure amplitude” and is represented by the symbol ΔP. A curve indicated by a thick broken line in FIG. 2 represents the in-cylinder pressure obtained by smoothing (smoothing) the in-cylinder pressure waveform during abnormal combustion. Hereinafter, the smoothed maximum value (maximum value) of the smoothed in-cylinder pressure is referred to as “smoothed maximum in-cylinder pressure” and is represented by the symbol Pmax.

  When abnormal combustion occurs, the temperature of the piston 12 rises. For this reason, if abnormal combustion occurs continuously for a plurality of cycles, the piston 12 may become hot. In particular, when a low-octane fuel other than the specified fuel is used, or when the intake air temperature is high, the temperature rise of the piston 12 during abnormal combustion is large, so the temperature of the piston 12 can be assured of strength. May rise beyond limits. According to the studies by the present inventors, the temperature increase width per abnormal combustion is deeply related to the magnitude of the in-cylinder pressure waveform (knock waveform) at the time of the abnormal combustion, and in particular, the above-described in-cylinder pressure amplitude ΔP and This is closely related to the maximum annealing pressure Pmax. Therefore, in the present embodiment, the values of the in-cylinder pressure amplitude ΔP and the maximum annealing in-cylinder pressure Pmax at the time of abnormal combustion are acquired, and the temperature increase width T of the piston 12 due to the abnormal combustion is calculated based on these values. When abnormal combustion occurs continuously for a plurality of cycles, the temperature increase of the piston 12 is estimated by calculating the temperature increase integrated value ΣT obtained by integrating the temperature increase width T due to each abnormal combustion.

  As described above, when a low-octane fuel other than the designated fuel is used or when the intake air temperature is high, the temperature rise of the piston 12 during abnormal combustion is large. When low-octane fuel is used or when the intake air temperature is high, the effect appears in the in-cylinder pressure waveform during abnormal combustion. Therefore, even when a low octane fuel is used or when the intake air temperature is high, the temperature of the piston 12 is estimated by estimating the temperature rise of the piston 12 based on the in-cylinder pressure amplitude ΔP and the smoothed maximum in-cylinder pressure Pmax. The rise can be estimated with high accuracy.

  FIG. 3 is a flowchart of a routine executed by the ECU 50 in the present embodiment. This routine is executed for each cycle in synchronization with the crank angle. According to the routine shown in FIG. 3, it is first determined whether or not the internal combustion engine 10 has been started (whether or not it is in operation) (step 100). When the internal combustion engine 10 is in operation, the temperature rise integrated value ΣT of the piston 12 is reset as ΣT = 0 (step 102).

  Subsequently, it is determined whether or not abnormal combustion occurs continuously for a plurality of cycles (step 104). The ECU 50 executes the above-described abnormal combustion detection operation for each cycle, and determines the presence or absence of abnormal combustion in each cycle. In this step 104, it is determined whether or not abnormal combustion occurs continuously for a plurality of cycles based on the history of determination results in the abnormal combustion detection operation. When abnormal combustion does not occur continuously for a plurality of cycles, it can be determined that there is no possibility that the temperature of the piston 12 exceeds the allowable limit. For this reason, when abnormal combustion does not occur continuously for a plurality of cycles, the process returns to step 100 without executing the estimation of the temperature rise of the piston 12 and the processes after step 100 are executed again.

  On the other hand, when abnormal combustion occurs continuously for a plurality of cycles, the temperature increase of the piston 12 is estimated as follows. First, the in-cylinder pressure waveform at the time of abnormal combustion detected by the in-cylinder pressure sensor 46 is smoothed to calculate the smoothed maximum in-cylinder pressure Pmax (step 106), and the in-cylinder pressure based on the in-cylinder pressure waveform at the time of abnormal combustion. The amplitude ΔP is calculated (step 108).

  Next, the temperature increase width T of the piston 12 per abnormal combustion is calculated based on the values of the maximum smoothed in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP calculated in steps 106 and 108 (step 110). FIG. 4 is a map for calculating the temperature rise width T of the piston 12. In this embodiment, the relationship between the maximum smoothed in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP and the temperature rise width T of the piston 12 is investigated in advance based on experiments, theories, empirical rules, and the like, as shown in FIG. It is summarized on the map. The ECU 50 stores a map as shown in FIG. 4 in advance. In step 110, the temperature increase width T of the piston 12 per abnormal combustion is calculated based on the values of the maximum smoothed in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP according to such a map. It can be predicted that the temperature of the piston 12 is increased by the calculated temperature increase width T due to the abnormal combustion occurring in the current cycle.

  Subsequently, the temperature increase integrated value ΣT is updated by adding the temperature increase width T calculated in step 110 to the temperature increase integrated value ΣT (step 112). Next, the updated temperature rise integrated value ΣT is compared with a predetermined reference value (criteria) (step 114). As a result, when the temperature rise integrated value ΣT is less than the reference value, the current temperature of the piston 12 still has a margin to the allowable limit, and there is no problem even if the abnormal combustion suppression control is not yet executed. It can be judged. In this case, the process returns to step 104, and the processes after step 104 are executed again.

  On the other hand, when the temperature rise integrated value ΣT is equal to or higher than the reference value in step 114, the current temperature of the piston 12 is approaching an allowable limit, and abnormal combustion is prevented in order to prevent further temperature rise. It is determined that the suppression control should be executed. Therefore, in this case, predetermined abnormal combustion suppression control is executed (step 116).

As the abnormal combustion suppression control in step 116, there are various methods. For example, the following control can be performed alone or in combination.
(1) Control for adding and injecting fuel from the fuel injector 20 into the cylinder. According to this control, even if abnormal combustion occurs, the flame caused by abnormal combustion can be extinguished or subdued by the fuel additionally injected into the cylinder, so that an abnormal increase in in-cylinder pressure is suppressed. The rise in the temperature of the piston 12 can be suppressed.
(2) Control to reduce the compression ratio. As a method for reducing the compression ratio, the substantial compression ratio can be lowered by changing the opening / closing timing of at least one of the intake valve 14 and the exhaust valve 16. Further, when the internal combustion engine 10 is provided with a mechanism (not shown) that makes the mechanical compression ratio variable, the mechanical compression ratio may be lowered by the mechanism. By reducing the compression ratio, occurrence of abnormal combustion can be suppressed.
(3) Control for retarding the ignition timing. By retarding the ignition timing, the in-cylinder temperature can be reduced and the occurrence of abnormal combustion can be suppressed.

  According to the control of the present embodiment described above, it is possible to accurately estimate (predict) the temperature rise width T of the piston 12 when abnormal combustion occurs. For this reason, when abnormal combustion occurs continuously, the abnormal combustion suppression control is surely executed before the temperature of the piston 12 exceeds the allowable limit, whereby the temperature of the piston 12 rises beyond the allowable limit. This can be reliably prevented and the piston 12 can be protected. In particular, due to special conditions such as when a non-designated low octane fuel is used or when the intake air temperature is high, the temperature of the piston 12 rises even when the temperature rise of the piston 12 during abnormal combustion tends to be large. Can be estimated with high accuracy. For this reason, it is possible to reliably prevent the temperature of the piston 12 from rising beyond an allowable limit even under such special conditions.

  Moreover, since abnormal combustion suppression control affects any one of fuel consumption, emission, drivability, etc. in any method, it is not preferable to perform it more than necessary. According to the present embodiment, the temperature increase of the piston 12 is accurately estimated (predicted), and the abnormal combustion suppression control is executed only when necessary to protect the piston 12, so that the abnormal combustion suppression is performed. The influence of the control on any of fuel consumption, emission, drivability, etc. can be minimized.

  In this embodiment, the in-cylinder pressure amplitude ΔP of the in-cylinder pressure waveform at the time of abnormal combustion is obtained from actually measured data detected by the in-cylinder pressure sensor 46 (step 108 above). Instead of using the sensor 46, the in-cylinder pressure amplitude ΔP may be obtained as follows. FIG. 5 is a map that defines the relationship between the type of fuel and the in-cylinder pressure amplitude ΔP. The ECU 50 can determine the fuel property (for example, octane number) based on information such as the trace knock ignition timing, and can determine the type of fuel according to the determined fuel property. The range of the in-cylinder pressure amplitude ΔP at the time of abnormal combustion takes a certain range according to the fuel properties. For this reason, it is possible to check the upper limit value of the in-cylinder pressure amplitude ΔP during abnormal combustion when the fuel is used for each type of fuel. The map in FIG. 5 is created by examining in advance the relationship between the type of fuel and the upper limit value of the in-cylinder pressure amplitude ΔP during abnormal combustion, and is stored in the ECU 50 in advance. The ECU 50 can obtain the upper limit value of the in-cylinder pressure amplitude ΔP during abnormal combustion by comparing the fuel type determined based on the trace knock ignition timing with the map of FIG. By estimating the temperature rise of the piston 12 using the upper limit value of the in-cylinder pressure amplitude ΔP calculated in this way, the estimation is made assuming that the abnormal combustion is the severest, so that the piston 12 can be reliably protected. it can. In addition, since the upper limit value of the in-cylinder pressure amplitude ΔP can be calculated without using the in-cylinder pressure sensor 46, the calculation load on the ECU 50 can be reduced. Instead of determining the fuel property based on the trace knock ignition timing, a fuel property sensor may be provided and the fuel property may be detected by the fuel property sensor.

  Further, in the present embodiment, the smoothed maximum in-cylinder pressure Pmax at the time of abnormal combustion is obtained from actually measured data detected by the in-cylinder pressure sensor 46 (step 106 above), but in the present invention, the in-cylinder pressure sensor 46 is used. Regardless, the smoothed maximum in-cylinder pressure Pmax may be obtained as follows. FIG. 6 is a map that defines the relationship between the operating state (engine speed and torque) of the internal combustion engine 10 and the upper limit value of the smoothed maximum in-cylinder pressure Pmax. The ECU 50 can calculate the torque based on, for example, the intake air amount and the fuel injection amount. The range of the maximum smoothed in-cylinder pressure Pmax at the time of abnormal combustion takes a certain range according to the operating state (engine speed and torque) of the internal combustion engine 10. For this reason, it is possible to examine in advance the relationship between the operating state (engine speed and torque) of the internal combustion engine 10 and the upper limit value of the smoothed maximum in-cylinder pressure Pmax during abnormal combustion. The map in FIG. 6 is created by examining in advance the relationship between the operating state (engine speed and torque) of the internal combustion engine 10 and the upper limit value of the maximum smoothed in-cylinder pressure Pmax during abnormal combustion. Stored in advance. Then, the ECU 50 can obtain the upper limit value of the maximum smoothed in-cylinder pressure Pmax at the time of abnormal combustion by comparing the current engine speed and torque with the map of FIG. By estimating the temperature rise of the piston 12 using the upper limit value of the smoothed maximum in-cylinder pressure Pmax calculated in this way, the estimation is made assuming that the abnormal combustion is the severest, so that the piston 12 is reliably protected. be able to. Further, since the upper limit value of the smoothed maximum in-cylinder pressure Pmax can be calculated without using the in-cylinder pressure sensor 46, the calculation load on the ECU 50 can be reduced.

  According to this embodiment, when abnormal combustion occurs, the temperature rise of the piston 12 is estimated to be particularly high by estimating the temperature rise of the piston 12 based on both information of the smoothed maximum in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP. It can be estimated (predicted) with accuracy. However, in the present invention, the temperature rise of the piston 12 may be estimated based on either one of the smoothed maximum in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP, and even in that case, the piston is sufficiently accurate. Twelve temperature rises can be estimated. Further, the temperature rise of the piston 12 is estimated based on in-cylinder pressure information other than the maximum annealing in-cylinder pressure Pmax and the in-cylinder pressure amplitude ΔP (for example, the deviation between the maximum annealing in-cylinder pressure Pmax and the maximum in-cylinder pressure during normal combustion). You can also.

  In the first embodiment described above, the in-cylinder pressure sensor 46 is the “in-cylinder pressure detecting means” in the fourth invention, and the smoothed maximum in-cylinder pressure Pmax is the “smoothed in-cylinder pressure in the fifth and sixth inventions”. The in-cylinder pressure amplitude ΔP corresponds to “the amplitude of the in-cylinder pressure waveform” in the fifth and seventh inventions, respectively. Further, when the ECU 50 executes the processes of the above steps 106 and 108, the “in-cylinder pressure information acquisition means” in the first invention executes the processes of the above steps 110 and 112. When the “piston temperature rise estimation means” executes the processing of step 110, the “temperature rise width acquisition means” of the second invention executes the processing of step 112, thereby executing the processing of step 112 above. When the “accumulating means” executes the processing of steps 114 and 116, the “determining means” in the third aspect of the invention acquires the upper limit value of the maximum smoothed in-cylinder pressure Pmax based on the map of FIG. According to the sixth aspect of the present invention, the “means for acquiring information relating to the maximum value of the smoothed in-cylinder pressure” is the trace knock ignition timing or the fuel By determining the fuel property based on the signal from the property sensor, the “fuel property determination means” in the seventh aspect obtains the upper limit value of the in-cylinder pressure amplitude ΔP based on the map of FIG. The “means for acquiring information related to the amplitude of the in-cylinder pressure waveform” in the invention is realized.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Piston 14 Intake valve 16 Exhaust valve 18 Spark plug 20 Fuel injector 22 Intake passage 24 Exhaust passage 26 Turbocharger 30 Air flow meter 32 Intercooler 34 Throttle valve 42 Exhaust purification catalyst 46 In-cylinder pressure sensor 47 Intake variable valve system 48 Exhaust variable valve gear 50 ECU

Claims (7)

In-cylinder pressure information acquisition means for acquiring information related to the in-cylinder pressure when abnormal combustion occurs in the internal combustion engine;
Piston temperature increase estimation means for estimating a temperature increase of the piston of the internal combustion engine due to the abnormal combustion based on the information acquired by the in-cylinder pressure information acquisition means;
A control device for an internal combustion engine, comprising: The piston temperature rise estimating means is
Based on the information, a temperature increase width acquisition means for acquiring a temperature increase width of the piston per one time of the abnormal combustion;
Integrating means for integrating the temperature increase width acquired by the temperature increase width acquiring means when the abnormal combustion occurs continuously;
The control apparatus for an internal combustion engine according to claim 1, comprising:   3. The internal combustion engine according to claim 1, further comprising a determination unit that determines whether or not the abnormal combustion suppression control for suppressing the occurrence of the abnormal combustion is necessary based on an estimation result of the piston temperature increase estimation unit. Engine control device. In-cylinder pressure detecting means for detecting the in-cylinder pressure of the internal combustion engine,
4. The control apparatus for an internal combustion engine according to claim 1, wherein the in-cylinder pressure information acquisition unit acquires the information based on an output of the in-cylinder pressure detection unit.   The in-cylinder pressure information acquisition means acquires one or both of information relating to the amplitude of the in-cylinder pressure waveform during the abnormal combustion and information relating to the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during the abnormal combustion. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control device is an internal combustion engine.   The in-cylinder pressure information acquisition means includes means for acquiring information on the maximum value of the smoothed in-cylinder pressure obtained by smoothing the in-cylinder pressure waveform during the abnormal combustion based on the operating state of the internal combustion engine. The control device for an internal combustion engine according to any one of claims 1 to 5. A fuel property judging means for judging the property of the fuel;
The in-cylinder pressure information acquisition means includes means for acquiring information relating to the amplitude of the in-cylinder pressure waveform during the abnormal combustion based on the fuel property determined by the fuel property determination means. The control apparatus for an internal combustion engine according to any one of claims 1 to 6.

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