JP2013204507A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, capable of preventing damage to a piston ring, by accurately grasping influence of pre-ignition on the piston ring.SOLUTION: A control device for an internal combustion engine includes: an in-cylinder pressure sensor 36 outputting an in-cylinder pressure detection value of a predetermined cylinder; a means for extracting behaviors of a low-frequency component and a high-frequency component from the in-cylinder pressure detection value at a compression stroke of the predetermined cylinder; a means for acquiring a peak valve Pmax of the low-frequency component and maximum amplitude PS of the high-frequency component, when pre-ignition occurs; a means for acquiring an index value corresponding to a degree of deformation of a piston ring 14, by reflecting weight parameters a, b, c, d, which are defined according to the peak value Pmax and the maximum amplitude PS, in frequency of the pre-ignition; and a means for preventing the pre-ignition by changing an operation state of an internal combustion engine 10, when the index value exceeds a criteria X'.

Description

  The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine control device equipped with an in-cylinder pressure sensor.

  Conventionally, for example, Japanese Patent Laid-Open No. 62-95437 has proposed a device for monitoring a combustion state based on a high-frequency component and a low-frequency component of in-cylinder pressure of an internal combustion engine. Specifically, in this device, focusing on the fact that there are specific normal patterns related to combustion energy in the low-frequency component and high-frequency component of the sensor output of in-cylinder pressure, the normal / abnormality is determined from the analysis of each component. It is determined that the engine misfire is determined.

JP-A-62-95437

  By the way, pre-ignition (pre-ignition) is one aspect of abnormal combustion that occurs in an internal combustion engine. Pre-ignition is a phenomenon in which the air-fuel mixture self-ignites from an overheated portion in the combustion chamber before the normal ignition timing of the spark plug during the compression stroke in the combustion cycle. When pre-ignition occurs, the air-fuel mixture is burned while being compressed, so the pressure and temperature in the combustion chamber may become abnormally high.

  Engine parts such as piston rings are designed to withstand the standard number of occurrences of pre-ignition. However, if the pre-ignition occurs more frequently than expected at the time of design due to the use of poor fuel or an increase in deposit accumulation, the piston ring will be deformed earlier, resulting in blow-by. There is a problem that gas and oil consumption increases.

  In the conventional technology described above, the combustion state is monitored using the low-frequency component and the high-frequency component of the sensor output of the in-cylinder pressure, but the technology for quantitatively evaluating the effect of preignition on the piston ring is disclosed. It has not been. For this reason, in the above-described conventional technology, it is impossible to accurately determine the degree of deformation of the piston ring due to pre-ignition and take measures, and improvement has been desired.

  The present invention has been made to solve the above-described problems, and controls an internal combustion engine capable of suppressing damage to the piston ring by accurately grasping the influence of pre-ignition on the piston ring. An object is to provide an apparatus.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
An in-cylinder pressure sensor for outputting an in-cylinder pressure detection value of a predetermined cylinder of the internal combustion engine;
Means for extracting the behavior of the low frequency component and the high frequency component from the in-cylinder pressure detection value in the compression stroke of the predetermined cylinder;
Means for respectively obtaining a peak value of the low frequency component and a maximum amplitude of the high frequency component when pre-ignition occurs;
Index value acquisition means for acquiring an index value corresponding to the degree of deformation of the piston ring by reflecting the weight parameter defined according to the peak value and the maximum amplitude in the occurrence frequency of the pre-ignition,
Pre-ignition suppression means for changing the operating state of the internal combustion engine to suppress the occurrence of pre-ignition when the index value exceeds a predetermined threshold;
It is characterized by having.

According to a second invention, in the first invention,
The index value acquisition means divides each of the generated pre-ignitions into each region set according to the peak value and the maximum amplitude, and sets the weight parameter to the number of occurrences of the pre-ignition belonging to each region. A value obtained by integrating each of the above is acquired as the index value.

According to a third invention, in the first or second invention,
The weight parameter is defined such that the index value increases as the peak value and / or the maximum amplitude increases.

A fourth invention is any one of the first to third inventions,
The pre-ignition suppression means includes means for setting the threshold value according to a travel distance of the internal combustion engine.

According to a fifth invention, in any one of the first to fourth inventions,
When the index value exceeds a second threshold set as a damage limit of the piston ring, it is further characterized by further comprising a notifying means for performing a predetermined warning.

A sixth invention is any one of the first to fifth inventions,
The pre-ignition suppression means includes air-fuel ratio control means for changing the air-fuel ratio of the internal combustion engine to a fuel rich side when the index value exceeds a predetermined threshold value.

  According to the first invention, the value that reflects the influence (weight parameter) of the peak value of the low frequency component of the in-cylinder pressure and the maximum amplitude of the high frequency component on the occurrence frequency of the pre-ignition is the degree of deformation of the piston ring due to the pre-ignition. Is obtained as an index value corresponding to. The greater the peak value and maximum amplitude during preignition, the greater the burden on engine parts. For this reason, according to the present invention, since the degree of deformation of the piston ring due to pre-ignition can be accurately determined based on the index value, it is possible to effectively take measures for suppressing the occurrence of pre-ignition. .

  According to the second invention, each of the generated pre-ignitions is divided into each region set according to the peak value and the maximum amplitude, and the weight parameter is reflected in the number of pre-ignition occurrences belonging to each region. The accumulated value is acquired as an index value. Therefore, according to the present invention, the pre-ignition peak value and maximum amplitude can be effectively reflected in the index value.

  According to the third invention, the weight parameter is defined such that the index value increases as the peak value and / or the maximum amplitude increases. For this reason, according to the present invention, since the index value increases as the load on the piston ring increases, the degree of deformation of the piston ring due to pre-ignition can be accurately determined based on the index value.

  According to the fourth aspect, the allowable range of the index value is set according to the travel distance of the internal combustion engine. Therefore, according to the present invention, it is possible to always set an appropriate allowable range for the index value that increases with the travel distance.

  According to the fifth aspect of the invention, a warning is issued when the index value exceeds a value set as the piston ring breakage limit. For this reason, according to this invention, it becomes possible to promote replacement | exchange before a piston ring breaks.

  According to the sixth aspect of the invention, when the index value exceeds the allowable range, the air-fuel ratio control for changing the air-fuel ratio of the internal combustion engine to the fuel rich side is executed. For this reason, according to the present invention, it is possible to effectively reduce the in-cylinder temperature and effectively suppress the occurrence of pre-ignition.

It is a schematic block diagram for demonstrating the system configuration | structure as Embodiment 1 of this invention. It is a figure which shows the generation | occurrence | production area | region of a preignition. It is a characteristic diagram which shows the in-cylinder pressure change when preignition occurs. It is a figure for demonstrating an example of the method of weighting the occurrence frequency of preignition. FIG. 5 is an example showing a change in the index value according to the travel distance. It is a flowchart which shows the routine performed in Embodiment 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a schematic configuration diagram for explaining a system configuration as a first embodiment of the present invention. As shown in FIG. 1, the system according to the present embodiment includes an internal combustion engine 10. The internal combustion engine 10 is configured as a spark ignition supercharged gasoline engine using gasoline as fuel. In addition, since the structure of a supercharger is already well-known in many literatures, the description and illustration are abbreviate | omitted in the following description.

  A piston 12 that reciprocates inside the cylinder of the internal combustion engine 10 is provided. A plurality of piston rings 14 are provided in the gap between the cylinder of the internal combustion engine 10 and the outer periphery of the piston 12 that reciprocates inside the cylinder. The piston rings 14 are respectively mounted in outer circumferential grooves formed on the outer periphery of the piston 12, and in addition to preventing leakage of compressed gas and combustion gas from the combustion chamber to the crankcase side, from the crankcase side to the combustion chamber. It has a function to prevent oil from being brought in.

  The internal combustion engine 10 includes a cylinder head 16. A combustion chamber 18 is formed between the piston 12 and the cylinder head 16. One end of an intake passage 20 and an exhaust passage 22 communicates with the combustion chamber 18. An intake valve 24 and an exhaust valve 26 are arranged at the communication portion between the intake passage 20 and the exhaust passage 22 and the combustion chamber 18, respectively.

  An air cleaner 28 is attached to the inlet of the intake passage 20. A throttle valve 30 is disposed downstream of the air cleaner 28. The throttle valve 30 is an electronically controlled valve that is driven by a throttle motor based on the accelerator opening.

  A spark plug 32 is attached to the cylinder head 16 so as to protrude from the top of the combustion chamber 18 into the combustion chamber 18. The cylinder head 16 is provided with a fuel injection valve 34 for injecting fuel into the cylinder. Further, the cylinder head 16 incorporates an in-cylinder pressure sensor (CPS) 36 for detecting the in-cylinder pressure of each cylinder.

  The system according to the present embodiment includes an ECU (Electronic Control Unit) 40 as shown in FIG. In addition to the in-cylinder pressure sensor 36 described above, various sensors such as a crank angle sensor 42 for detecting the rotational position of the crankshaft are connected to the input portion of the ECU 40. Further, various actuators such as the throttle valve 30, the spark plug 32, and the fuel injection valve 34 described above are connected to the output portion of the ECU 40. The ECU 40 controls the operating state of the internal combustion engine 10 based on various types of input information.

[Operation of Embodiment 1]
First, with reference to FIG. 2 and FIG. 3, the tendency of occurrence of pre-ignition in a gasoline engine with a supercharger will be described. FIG. 2 is a diagram showing a pre-ignition occurrence region, and FIG. 3 is a characteristic diagram showing a change in in-cylinder pressure when pre-ignition occurs. In a gasoline engine with a supercharger, as shown in FIG. 2, for example, pre-ignition is likely to occur in a low rotation and high load region in an operation region determined according to the engine speed and torque. In the following description, the term “pre-ignition” simply refers to pre-ignition at low speed that occurs in a low rotation and high load region as shown in FIG.

  When pre-ignition occurs, the air-fuel mixture burns while being compressed, so that the pressure and temperature in the combustion chamber become abnormally high as compared to normal combustion, as shown in FIG. For this reason, when pre-ignition occurs, the piston ring 14 is deformed, and there is a possibility that the amount of blow-by gas and oil consumption (LOC) (Lubrication Oil Consumption) may increase rapidly. Specifically, the piston ring 14 is designed to withstand a target travel distance (for example, 300,000 km) to be guaranteed. However, if a situation occurs where the frequency of pre-ignition increases more than expected due to the use of poor fuel or an increase in the amount of deposit, the deformation of the piston ring 14 progresses earlier than that, which is practically used. Problems may also arise.

  Here, the influence of the pre-ignition on the piston ring 14 varies depending not only on the occurrence frequency of the pre-ignition but also on the size thereof. That is, as shown in FIG. 2, when pre-ignition occurs, the in-cylinder pressure rapidly increases. Focusing on the maximum in-cylinder pressure (hereinafter referred to as “peak value”) Pmax of the low frequency component and the maximum value of amplitude of the high frequency component (hereinafter referred to as “maximum amplitude”) PS at this time, Pmax and / or PS are The larger the value is, the greater the influence on the piston ring 14 (the amount of deformation during pre-ignition) becomes. For this reason, when the occurrence frequency of pre-ignition (for example, an integrated value of the occurrence frequency) is simply used as an index of the deformation amount of the piston ring 14, it is possible to accurately determine the possibility of the piston ring 14 being damaged. Can not.

Therefore, in the apparatus of the first embodiment, when evaluating the influence of the pre-ignition on the piston ring 14, the pre-ignition occurrence frequency (number of times) is weighted by the peak value Pmax and the maximum amplitude PS. FIG. 4 is a diagram for explaining an example of a method of weighting the occurrence frequency of pre-ignition. In the example shown in FIG. 4, in the generated pre-ignition, the behaviors of the high frequency component and the low frequency component are extracted from the detection signal of the in-cylinder pressure sensor 36, the maximum amplitude PS and the peak value Pmax are specified, respectively, and the maximum amplitude It is divided into any one of regions a, b, c, and d determined according to PS and peak value Pmax. Next, according to the following equation (1), an index value is calculated by weighting the number of pre-ignitions A, B, C, and D belonging to each region.
Index value = aA + bB + cC + dD (1)

  In the above equation (1), a, b, c, and d are weight parameters assigned to the respective areas a, b, c, and d, and a larger value (that is, a < b <c <d) is set. According to the above equation (1), the index value is calculated as a larger value as the number of pre-ignitions belonging to the region where Pmax and / or PS is larger. Thereby, the index value for preventing the piston ring from being damaged by pre-ignition can be calculated with high accuracy.

  The calculated index value is used for preignition suppression control. FIG. 5 is an example showing a change in the index value according to the travel distance. In the example shown in this figure, a criterion X ′ is set, which increases as the travel distance increases. The criterion X ′ is a standard line for the number of times of occurrence of pre-ignition with respect to the travel distance, and is a design reference value that allows the target travel distance to be broken if the standard line is not exceeded. As shown in FIG. 5, when the calculated index value is larger than the criterion X ′, as a control for suppressing the pre-ignition, an air-fuel ratio control in which the air-fuel ratio of the internal combustion engine 10 is a rich air-fuel ratio is performed. Executed. Thereby, since the index value is controlled to be smaller than the criterion X ′, it is possible to effectively suppress the progress of the deformation of the piston ring.

  In the example shown in FIG. 5, the number of pre-ignition occurrences when the target travel distance is run along the standard line is set as the criterion X. The criterion X is a fixed value that is set regardless of the travel distance, and is used for determining the damage limit of the piston ring. In the system according to the first embodiment, when the index value exceeds the criterion X, the MIL is turned on. Accordingly, the user can be informed of the limit of the part, so that it is possible to promote replacement of the part before it is damaged.

[Specific Processing in First Embodiment]
Next, specific processing of control executed in the system according to the first embodiment will be described with reference to a flowchart. FIG. 6 is a flowchart showing a routine that the ECU 40 executes in the first embodiment. In the routine shown in FIG. 6, it is first determined whether or not the index value (aA + bB + cC + dD) is smaller than the criterion X ′ (step 100). The pre-ignition is classified into one of the regions a, b, c, and d by detecting the maximum in-cylinder pressure Pmax and the maximum amplitude PS by the in-cylinder pressure sensor 36. Specifically, the index value is calculated using the number of pre-ignitions A, B, C, D belonging to each region and the weight parameters a, b, c, d of each region. X ′ is a criterion set as a standard value of the number of occurrences of pre-ignition according to the travel distance, and is set so as to increase as the travel distance increases. Here, X ′ corresponding to the travel distance of the internal combustion engine 10 is specified. As a result of the determination in this step, when aA + bB + cC + dD <X ′ is not established, it is determined that the number of pre-ignition occurrences exceeds the standard line, the process proceeds to the next step, and the pre-ignition suppression control is performed. It is executed (step 102). Here, specifically, air-fuel ratio control for varying the air-fuel ratio of the internal combustion engine 10 to the rich side is executed.

  On the other hand, if the establishment of aA + bB + cC + dD <X ′ is recognized in step 100, or after the processing of step 100, the process proceeds to the next step, and whether or not the index value (aA + bB + cC + dD) is smaller than the criterion X. Is determined (step 104). X is a criterion for determining the breakage limit of the piston ring 14, and a preset value is read. As a result of the determination in this step, if establishment of aA + bB + cC + dD <X is not recognized, it is determined that the piston ring 14 has reached the breakage limit, the process proceeds to the next step, MIL is lit, and the user is informed. Exchange of the piston ring 14 is prompted (step 106). On the other hand, if it is determined in step 104 that aA + bB + cC + dD <X is established, it is determined that the piston ring 14 has not yet reached the breakage limit, and this routine is immediately terminated.

  As described above, according to the system of the present embodiment, the index value obtained by adding the weight to the number of pre-ignitions based on the maximum in-cylinder pressure Pmax and the maximum amplitude PS at the time of pre-ignition is calculated. The degree of deformation can be accurately determined. Thereby, since the execution time of preignition suppression control can be determined appropriately, the situation where the piston ring 14 breaks before traveling the target travel distance can be effectively suppressed.

  Further, according to the system of the above-described embodiment, when the index value exceeds the damage limit of the piston ring 14, a warning by MIL is performed, so that the user can be notified of the replacement time of the piston ring 14 effectively. Is possible.

  By the way, in the system of the first embodiment described above, the air-fuel ratio control that makes the air-fuel ratio of the internal combustion engine 10 rich as the pre-ignition suppression control has been described, but other known control for suppressing the pre-ignition is performed. It is good.

  In the system of the first embodiment described above, the MIL is turned on as the notification means, but other known notification means such as sound and vibration may be used.

  In the system of the first embodiment described above, the areas determined according to the maximum amplitude PS and the peak value Pmax are classified into four areas a, b, c, and d. Is not limited to this, and the region may be classified in more detail.

  In the above-described first embodiment, the criterion X ′ corresponds to the “threshold value” of the first invention, and the ECU 40 executes the process of step 102 to execute the first step. The “pre-ignition suppression means” in the invention of the present invention executes the processing of step 106, thereby realizing the “notification means” in the fifth aspect of the invention.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Piston 14 Piston ring 16 Cylinder head 18 Combustion chamber 20 Intake passage 22 Exhaust passage 24 Intake valve 26 Exhaust valve 28 Air cleaner 30 Throttle valve 32 Spark plug 34 Fuel injection valve 36 Cylinder pressure sensor (CPS)
40 ECU (Electronic Control Unit)
42 Crank angle sensor

Claims (6)

An in-cylinder pressure sensor for outputting an in-cylinder pressure detection value of a predetermined cylinder of the internal combustion engine;
Means for extracting the behavior of the low frequency component and the high frequency component from the in-cylinder pressure detection value in the compression stroke of the predetermined cylinder;
Means for respectively obtaining a peak value of the low frequency component and a maximum amplitude of the high frequency component when pre-ignition occurs;
Index value acquisition means for acquiring an index value corresponding to the degree of deformation of the piston ring by reflecting the weight parameter defined according to the peak value and the maximum amplitude in the occurrence frequency of the pre-ignition,
Pre-ignition suppression means for changing the operating state of the internal combustion engine to suppress the occurrence of pre-ignition when the index value exceeds a predetermined threshold;
A control device for an internal combustion engine, comprising:   The index value acquisition means divides each of the generated pre-ignitions into each region set according to the peak value and the maximum amplitude, and sets the weight parameter to the number of occurrences of the pre-ignition belonging to each region. 2. The control device for an internal combustion engine according to claim 1, wherein a value obtained by reflecting each of the values is acquired as the index value.   The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the weight parameter is defined such that the index value increases as the peak value and / or the maximum amplitude increases.   4. The control apparatus for an internal combustion engine according to claim 1, wherein the pre-ignition suppression means includes means for setting the threshold value in accordance with a travel distance of the internal combustion engine.   5. The apparatus according to claim 1, further comprising a notification unit that performs a predetermined warning when the index value exceeds a second threshold value set as a damage limit of the piston ring. A control device for an internal combustion engine according to claim.   2. The pre-ignition suppression means includes air-fuel ratio control means for changing the air-fuel ratio of the internal combustion engine to a fuel rich side when the index value exceeds a predetermined threshold value. The control apparatus for an internal combustion engine according to any one of claims 5 to 6.

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