JP2013144935A - Control device for internal combustion engine - Google Patents

Abstract

The present invention relates to a control device for an internal combustion engine, and an object thereof is to provide a control device for an internal combustion engine capable of removing deposits for the purpose of suppressing a preg (low speed preg) occurring in a high load region of low engine speed. And
[Solution]
As shown in FIG. 4, it is determined whether or not the prag has continuously occurred (step 100). If it is determined that the prag is continuously generated, it can be determined that the pledge is derived from the deposit, and therefore, it is determined whether or not the operating range of the engine 10 is in the low rotation and high load range (step 110). When the engine is in an operation region other than the low rotation and high load regions, over-advance control is executed. When executing the advance angle control, the ignition timing is advanced so that the smoothing Pmax approaches the guaranteed pressure corresponding to the guaranteed material strength value of the piston.
[Selection] Figure 4

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus that removes deposits accumulated in a combustion chamber.

  2. Description of the Related Art Conventionally, in an internal combustion engine in which a fuel / air mixture is ignited and burned by sparks of an ignition plug, before the ignition by the ignition plug, abnormal combustion in which the mixture in the cylinder self-ignites (hereinafter also referred to as “preg”). .) Is known to occur. It is also known that deposits accumulated in the combustion chamber are one of the causes of the occurrence of pre-ignition.

  As a deposit removal technique for the purpose of suppressing the occurrence of pre-ignition, for example, Patent Document 1 discloses control of an internal combustion engine that alternately executes fuel cut control to the pre-ignition cylinder and ignition timing retard control of the pre-ignition cylinder. An apparatus is disclosed. According to this control device, knocking is intentionally generated in the pre-ignition cylinder by executing the above two controls alternately, and deposits can be removed by the vibration.

  Moreover, although there is no mention about the relationship between the occurrence of deposits and deposits, Patent Document 2 discloses that the ignition timing of the spark plug is determined by MBT (Minimum spark advance for Best Torque) when deposit adhesion to the spark plug is detected. A control device for an internal combustion engine that performs over-advance angle control for advancing ahead of time is disclosed. According to this control device, it is possible to raise the peak value of the temperature in the combustion chamber by executing the over-advance angle control, and to oxidize and remove the deposit attached around the spark plug.

JP 9-2222030 A JP 2008-267293 A

  By the way, when the frequency of use of the engine operation region is taken into account, the plag that occurs in the high load region of the engine low rotation (hereinafter referred to as “low speed preg”) is another region, for example, the high load region of the engine high rotation. The probability of occurrence is higher than that of the generated plag (hereinafter referred to as “high-speed plag”). For this reason, it is desirable that the occurrence of low-speed paging can be suppressed more preferentially than the high-speed paging and other types of paging. However, the deposit removal technique specialized in the suppression of low-speed pre-ignition is not disclosed in the above-mentioned Patent Documents 1 and 2, and therefore it can be said that there is room for development.

  The present invention has been made in view of the above-described problems. That is, an object of the present invention is to provide a control device for an internal combustion engine capable of removing deposits for the purpose of suppressing the occurrence of low-speed pre-ignition.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
Ignition means for igniting the air-fuel mixture sucked into the cylinder of the internal combustion engine;
In the internal combustion engine, ignition timing control means for controlling the advance of the ignition timing of the ignition means in order to generate a pseudo pre-ignition that produces a maximum value of in-cylinder pressure that is lower than when pre-ignition occurs;
Low-speed pre-ignition generation region determination means for determining whether the operation region of the internal combustion engine is in a predetermined low-speed pre-ignition generation region defined by the engine speed and load;
When the operation region is in the predetermined low-speed pre-ignition generation region, advance angle control prohibiting means for prohibiting advance angle control by the ignition timing control means;
It is characterized by providing.

The second invention is the first invention, wherein
Pre-ignition detection means for detecting occurrence of pre-ignition;
Continuous detection condition determination means for determining success or failure of a predetermined continuous detection condition related to whether or not the occurrence of preignition by the preige detection means is continuously detected;
The ignition timing control means controls the advance of the ignition timing when the continuous detection condition is satisfied.

The third invention is the first or second invention, wherein
The ignition timing control means advances the ignition timing so that the maximum value of the in-cylinder pressure generated when the pseudo preignition is generated approaches a guaranteed pressure corresponding to a predetermined material strength guaranteed value determined for each piston used in the internal combustion engine. It is characterized by angle control.

  The pseudo pre-ignition causes a maximum value of the in-cylinder pressure lower than that at the time of occurrence of the pre-ignition to stably peel the deposit in the combustion chamber. According to the first invention, when the operation region of the internal combustion engine is in a predetermined low-speed preg generation region, the generation of this pseudo preignition can be prohibited. In other words, the pseudo preignition can be generated when the operating range of the internal combustion engine is outside the low speed preg generation region. In other words, according to the present invention, deposits can be positively peeled outside the low-speed preg generation region, so that the occurrence of pre-slag that occurs in the low-speed preg generation region, i.e., low-speed preg, can be suppressed.

  The occurrence of prags due to deposit deposition is characterized by being likely to occur continuously as the amount of deposit deposition increases. In this regard, according to the second invention, it is possible to determine the continuous occurrence of pre-ignition as the predetermined continuous detection condition, and generate the pseudo pre-ignition when the continuous detection condition is satisfied. Therefore, according to the present invention, it is possible to reliably reduce the deposit accumulation amount when deposits are generated from the deposits.

  The effect of deposit peeling by pseudo pre-ignition increases as the maximum value of the in-cylinder pressure at the time of occurrence thereof increases. In this regard, according to the third aspect of the invention, the ignition timing is set so that the maximum value of the in-cylinder pressure generated when the pseudo pre-ignition occurs approaches the guaranteed pressure corresponding to a predetermined material strength guaranteed value determined for each piston used in the internal combustion engine. Advance angle control is possible. Therefore, according to the present invention, while ensuring the reliability of the piston, it is possible to increase the maximum value of the in-cylinder pressure at the time of occurrence of pseudo pre-ignition and to exhibit the deposit peeling effect.

It is a figure for demonstrating the system configuration | structure of embodiment of this invention. FIG. 2 is a diagram showing an operation region of the engine 10. It is a figure for demonstrating transition of the deposit thickness deposited on a piston at the time of performing pseudo-preg generation control. It is a flowchart which shows the routine of pseudo pre-ignition generation control performed by ECU32 in embodiment.

[Description of system configuration]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a diagram for explaining a system configuration according to an embodiment of the present invention. As shown in FIG. 1, the system of this embodiment includes an engine 10 as an internal combustion engine. The engine 10 shown in FIG. 1 is an in-line four-cylinder engine, but the number of cylinders and the cylinder arrangement of the engine applicable to this embodiment are not limited to this.

  In the cylinder 12 of the engine 10, an injector 14 that directly injects fuel into the cylinder 12, an ignition plug 16 that ignites an air-fuel mixture in the cylinder, and a pressure in the cylinder 12 (hereinafter referred to as “in-cylinder pressure P”). In-cylinder pressure sensors 18 to be detected are respectively installed. The injector 14 is connected to a common rail 20 common to them. The common rail 20 is connected to a fuel tank (not shown).

  In addition, as shown in FIG. 1, the system of the present embodiment includes a turbocharger 22. The turbocharger 22 has an exhaust turbine 22a and an intake compressor 22b driven by the exhaust turbine 22a. The exhaust turbine 22 a is disposed in the middle of the exhaust passage 24. The intake air compressor 22b is disposed in the intake passage 26.

  In addition, the system of this embodiment includes an ECU (Electronic Control Unit) 32 as a control device. An injector 14, a spark plug 16, and the like are connected to the output side of the ECU 32. In addition to the in-cylinder pressure sensor 18, a crank angle sensor 28 that detects the engine speed, a throttle opening sensor 30 that detects the opening of the throttle valve, and the like are connected to the input side of the ECU 32. The ECU 32 can control various actuators such as the injector 14 and the spark plug 16 based on these sensor signals.

[Features of the embodiment]
As described above, deposit accumulation in the cylinder of the internal combustion engine is one of the causes of the occurrence of pre-ignition. The occurrence of plague due to deposit accumulation is caused by the deposit accumulated on the piston or the like serving as an ignition source when the engine 10 is operated at a high load (in-cylinder high temperature). Here, the deposit-derived plague is characterized by being easily generated continuously as the deposit accumulation amount increases.

  Further, as described above, the high load region with a low engine speed is used more frequently than the high load region with a high engine speed. In addition, when the low speed pre-ignition occurs, the smoothing Pmax (referring to the average processing value of the maximum value of the combustion pressure; the same applies hereinafter) that exceeds the infinite guarantee in strength. Therefore, when low-speed preggs derived from deposits are continuously generated, the engine 10 may be damaged. Therefore, in the present embodiment, in order to avoid such a problem, when a deposit-derived prag is detected, pseudo-prag generation control described below is executed.

[Pseudo Plague Generation Control]
Specifically, the pseudo-Pleig generation control is a control for generating a pseudo Pleig that generates an annealing Pmax lower than the pressure at the time of Pleig generation by controlling the ignition timing of the spark plug 16 by an advance angle control. If the advance timing of the ignition timing is controlled, the maximum value of the combustion pressure can be increased, so that the smoothing Pmax can be increased. If the annealing Pmax can be increased, the deposit deposited on the piston or the like can be peeled off, so that the amount deposited can be reduced.

  However, when executing the pseudo-preg generation control, the ignition timing is exceeded while monitoring the in-cylinder pressure P so that the annealing pressure Pmax is lower than the guaranteed pressure (design value) corresponding to the material strength guaranteed value of the piston of the engine 10. Advance angle control. If the ignition timing is over-advanced while monitoring the in-cylinder pressure P, the same smoothing Pmax occurs when the ignition timing is advanced, preventing unintentional damage to the piston, etc. it can. It should be noted that the deposit peeling effect becomes higher as the annealing Pmax is higher. For this reason, when the pseudo-preg generation control is executed, the ignition timing is gradually advanced unless the guaranteed pressure is reached. That is, in the pseudo-preg generation control, the ignition timing is advanced so that the annealing Pmax approaches the guaranteed pressure.

  Further, in the present embodiment, pseudo pre-ignition generation control is executed in the operation region of the engine 10 excluding the low load and high load region. FIG. 2 is a diagram showing an operation region of the engine 10. The low speed pre-ignition occurs in the operation region shown as the low-speed pre-ignition generation region in FIG. Here, as described above, when low-speed preggs derived from deposits occur continuously, the engine 10 may be damaged. For this reason, in the present embodiment, pseudo-preg generation control is positively executed in a region other than the low-speed preg generation region shown in FIG. By so doing, it is possible to effectively suppress the occurrence of low-speed prags while permitting the generation of plows in regions other than the low rotation and high load regions.

FIG. 3 is a diagram for explaining the transition of the deposit thickness accumulated on the piston when the pseudo-preg generation control is executed. As shown in FIG. 3, the deposited deposit thickness increases as the operating time of the engine 10 elapses. The thickness x shown in FIG. 3 corresponds to the thickness at which the probability of occurrence of pre-age suddenly increases when the value exceeds that value. In this regard, if the pseudo pre-ignition generation control is executed at t ₁ to t ₂ , t _{3 to} t ₄ , and t _{5 to} t ₆ in FIG. 3, the deposition deposit can be reduced during that period. That is, since the deposited deposit thickness can be kept below the thickness x, the occurrence of deposits due to deposits can be suppressed.

[Specific processing in the embodiment]
Next, specific processing for realizing the above-described functions will be described with reference to FIG. FIG. 4 is a flowchart showing a routine of pseudo pre-ignition generation control executed by the ECU 32 in the present embodiment.

  As shown in FIG. 4, the ECU 32 first determines whether or not pre-ignition has occurred continuously (step 100). Specifically, when the in-cylinder pressure P detected from the in-cylinder pressure sensor 18 continuously exceeds (for example, five times) a pressure (set value) corresponding to the pressure at the time of occurrence of the pre-ignition, the ECU 32 It is determined that continuous occurrence has occurred. In this step, when it is determined that the prig is continuously generated, the ECU 32 determines that the peg is derived from the deposit, and proceeds to step 110. On the other hand, when it is determined that the praigs are not continuously generated, the ECU 32 determines that the praigs themselves are not generated or that the praigs are generated but not originating from the deposit, and the process returns to step 100.

  In step 110, the ECU 32 determines whether or not the operation region of the engine 10 is in a low rotation and high load region. Specifically, the ECU 32 specifies an operation region from sensor outputs of the crank angle sensor 28 and the throttle opening sensor 30. When the ECU 32 is in an operation region other than the low rotation and high load regions, the ECU 32 proceeds to 120 and executes over-advance control. The execution of this over-advance angle control is continued until the engine 10 is stopped (step 130). It should be noted that, when the advance angle control is executed, the ignition timing is advanced so that the smoothing Pmax approaches the guaranteed pressure as described above. On the other hand, if the operating region of the engine 10 is a low rotation and high load region in step 110, the ECU 32 returns to step 100.

  As described above, according to the routine shown in FIG. 4, when it is determined that the pre-ignition has occurred continuously, it is possible to execute the over-advance control after confirming that the operation region is other than the low rotation and high load regions . Therefore, the deposit can be positively peeled off when deposits originated in the operation region other than the low rotation and high load regions. Therefore, generation | occurrence | production of a low-speed preg can be suppressed effectively.

By the way, in the said embodiment, although demonstrated on the premise of the system structure provided with the turbocharger 22, it is applicable also to a non-turbo type system. This is because deposit-derived low-speed pregging may occur even in non-turbo systems.
Further, in the above-described embodiment, the occurrence of pre-ignition is detected by the in-cylinder pressure sensor 18, but a pre-ignition detection device that performs pre-detection based on the vibration frequency may be attached to the engine 10 to detect the pre-ignition. Further, the occurrence of pre-ignition may be detected by calculation processing of the ECU 32.

In the embodiment described above, the spark plug 16 corresponds to the “igniting means” in the first invention.
In the above-described embodiment, the ECU 32 executes the process of step 120 in FIG. 4 so that the “ignition timing control means” in the first invention executes the process of step 110 in FIG. The “low-speed pre-gage generation area determination means” in the first aspect of the invention executes the process of returning to step 100 when it is determined in step 110 that the operation area of the engine 10 is in the low rotation and high load area The “advance angle control prohibiting means” in the first invention is realized.
In the embodiment described above, the in-cylinder pressure sensor 18 corresponds to the “preg detection means” in the second invention.
In the above-described embodiment, the “continuous detection condition determining means” in the second aspect of the present invention is realized by the ECU 32 executing the process of step 100 of FIG.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 16 Spark plug 18 In-cylinder pressure sensor 28 Crank angle sensor 30 Throttle opening sensor 32 ECU

Claims (3)

Ignition means for igniting the air-fuel mixture sucked into the cylinder of the internal combustion engine;
In the internal combustion engine, ignition timing control means for controlling the advance of the ignition timing of the ignition means in order to generate a pseudo pre-ignition that produces a maximum value of in-cylinder pressure that is lower than when pre-ignition occurs;
Low-speed pre-ignition generation region determination means for determining whether the operation region of the internal combustion engine is in a predetermined low-speed pre-ignition generation region defined by the engine speed and load;
When the operation region is in the predetermined low-speed pre-ignition generation region, advance angle control prohibiting means for prohibiting advance angle control by the ignition timing control means;
A control device for an internal combustion engine, comprising: Pre-ignition detection means for detecting occurrence of pre-ignition;
Continuous detection condition determination means for determining success or failure of a predetermined continuous detection condition related to whether or not the occurrence of preignition by the preige detection means is continuously detected;
2. The control device for an internal combustion engine according to claim 1, wherein the ignition timing control means controls the advance of the ignition timing when the continuous detection condition is satisfied. 3.   The ignition timing control means advances the ignition timing so that the maximum value of the in-cylinder pressure generated when the pseudo preignition is generated approaches a guaranteed pressure corresponding to a predetermined material strength guaranteed value determined for each piston used in the internal combustion engine. The control device for an internal combustion engine according to claim 1 or 2, wherein the control is performed by angle control.

Images