JP5920036B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus having an oil jet stop function for cooling a piston.

  As a prior art, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 10-68319), a control device for an internal combustion engine having an oil jet stop function is known. In the prior art, in a low load region, the oil injection by the oil jet is stopped to suppress the cooling of the piston and to prevent the deposit from adhering to the top surface of the piston.

JP-A-10-68319 JP 2003-97269 A

  In the above-described prior art, there is a problem that the oil jet stop does not function effectively when deposits are already attached to the top surface of the piston. That is, in this case, even if the oil jet is stopped, the deposited deposit remains, so when the engine operating region shifts to a region where pre-ignition is likely to occur (pre-ignition region), the deposit is a heat source. There is a possibility that preignition will occur as an (ignition source).

  The present invention has been made to solve the above-described problems, and the object of the present invention is to perform pre-ignition, including the case where the deposit is attached to the top surface of the piston and the pre-ignition region is transferred. An object of the present invention is to provide a control device for an internal combustion engine that can be stably suppressed.

The first invention comprises an oil jet that injects oil toward a piston of an internal combustion engine,
When the region transition operation in which the operation state of the internal combustion engine shifts from the non-pre-ignition region to the pre-ignition region is performed on the basis of the pre-ignition region that is an operation region in which pre-ignition is likely to occur, the oil jet is continuously used. The injection is prohibited, and the continuous injection of oil is started after the execution period set as the period necessary for reducing the amount of deposit adhering to the piston to the maximum allowable amount or less after the prohibition of the continuous injection . Oil jet control means;
When the intermittent injection condition set based on at least one of the temperature of the piston and the oil injection stop time is satisfied during the execution period, the intermittent injection of oil is executed, and the execution period elapses, or Means for stopping the intermittent injection and shifting to continuous oil injection when cooling of the piston by the intermittent injection is insufficient;
When the region migration operation is performed, it executes the inhibiting suppression control preignition, before and preignition suppression means you line period ends the restraint control after a lapse, characterized in that it comprises a.

According to the second invention, the execution period is set according to the period as a minimum period necessary for reducing the amount of deposit attached to the piston to an amount capable of suppressing the occurrence of pre-ignition. Yes.

The third invention comprises preignition detection means for detecting occurrence of preignition,
It is determined whether or not suppression of pre-ignition is completed based on a detection result of the pre-ignition detection means, and the execution is performed when it is determined that suppression of pre-ignition is not completed even after the execution period has elapsed. Control period correcting means for extending the period and continuing the intermittent injection of oil .

According to the present invention, Ru with the execution period is extended by the control period correcting means, means for learning and storing a relationship between the operating state of the internal combustion engine.

According to the first aspect of the present invention, during the region transition operation, the pre-ignition suppression control and the control that inhibits the continuous oil injection and suppresses the adhesion of deposits can be combined and executed for a predetermined execution period. Thereby, the adhesion amount of a deposit can be reduced stably, suppressing generation | occurrence | production of preignition. That is, even if the deposit peeled off from the piston by the control for suppressing the adhesion of the deposit can serve as an ignition source, it is possible to suppress the occurrence of pre-ignition due to this deposit by the suppression control. Therefore, the removal of deposit can proceed stably. Further, since the length of the execution period can be set to the minimum necessary, the influence of the suppression control on the engine performance and drivability can be minimized. Furthermore, during the execution period, intermittent injection of oil can be executed according to the necessity of cooling the piston or the like.

According to a second aspect of the invention, execution time period may be adhered amount of deposits adhered to the piston is set as the minimum period necessary to decrease to an amount capable of suppressing the occurrence of pre-ignition. Thus, after the execution period has elapsed, the amount of deposit can be reduced to the extent that pre-ignition does not occur, and pre-ignition can be stably suppressed.

According to the third aspect of the invention, it is possible to extend the execution period of the suppression control based on the pre-ignition occurrence state at the time when the suppression control should be terminated, and to continue the intermittent injection of oil as necessary . Thereby, for example, even when deposits larger than expected are attached to the top surface of the piston, the execution period of each suppression control can be extended in accordance with the attached amount. Therefore, even if the deposit adhesion amount fluctuates, pre-ignition can always be stably suppressed.

According to the fourth aspect of the invention, the relationship between the execution period extended by the control period correction means and the operating state of the internal combustion engine can be stored and learned. As a result, the execution period can be extended to an appropriate length without receiving pre-ignition disturbance due to other factors.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. In Embodiment 1 of this invention, it is explanatory drawing which shows an example of the driving | operation area | region set based on an engine speed and an engine torque, and an area | region transfer driving | operation. In Embodiment 1 of this invention, it is a timing chart which shows the engine torque at the time of area | region transfer driving | operation, piston temperature, and the deposit adhesion amount of a piston top surface. In Embodiment 1 of this invention, it is a flowchart which shows an example of the control performed by ECU. In Embodiment 2 of this invention, it is a characteristic diagram which shows the relationship between piston temperature and the deposit adhesion amount in a low load-intermediate load area | region. In Embodiment 2 of this invention, it is a timing chart which shows the engine torque at the time of area | region transfer driving | operation, piston temperature, and the deposit adhesion amount of a piston top surface. In Embodiment 3 of this invention, it is explanatory drawing which shows an example of the driving | operation area | region of an engine, and an area | region transfer driving | operation. In Embodiment 3 of this invention, it is a timing chart which shows the engine torque at the time of area | region transfer operation | movement, piston temperature, and the deposit adhesion amount of a piston top surface. In Embodiment 4 of this invention, it is a flowchart which shows an example of the control performed by ECU. In Embodiment 5 of this invention, it is explanatory drawing which shows an example of a driving | operation area | region of an engine, and an area | region transfer driving | operation. In Embodiment 5 of this invention, it is a timing chart which shows the engine torque at the time of area | region transfer driving | operation, engine speed, piston temperature, and the deposit adhesion amount of a piston top surface.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes an engine 10 as an internal combustion engine mounted on a vehicle or the like. FIG. 1 illustrates only one cylinder among a plurality of cylinders mounted on the engine 10, and the present invention is applied to an internal combustion engine having an arbitrary number of cylinders including a single cylinder. A combustion chamber 14 is formed by a piston 12 in the cylinder of the engine 10, and the piston 12 is connected to a crankshaft 16. The engine 10 also includes an intake passage 18 that sucks intake air into the cylinder and an exhaust passage 20 through which exhaust gas is discharged from the cylinder. The intake passage 18 is provided with an electronically controlled throttle valve 22 for adjusting the amount of intake air, and the exhaust passage 20 is provided with a catalyst 24 for purifying exhaust gas.

  The cylinder includes a fuel injection valve 26 that injects fuel into the intake port, an ignition plug 28 that ignites the air-fuel mixture in the cylinder, an intake valve 30 that opens and closes the intake port, and an exhaust valve 32 that opens and closes the exhaust port. And are provided. Further, the engine 10 includes a supercharger 34 that supercharges intake air using exhaust pressure. The supercharger 34 includes a turbine 34 a provided in the exhaust passage 20 and a compressor 34 b provided in the intake passage 18. When the supercharger 34 operates, the turbine 34a receives the exhaust pressure and drives the compressor 34b, whereby the compressor 34b supercharges the intake air. The exhaust passage 20 is provided with a waste gate valve 36 for adjusting the amount of exhaust gas passing through the turbine 36a, and the intake passage 18 is provided with an intercooler 38 for cooling intake air.

  The engine 10 includes a lubrication system including an oil pan 40, an oil jet 42, an oil pump 44, a flow control valve 46, a relief valve 48, and the like. The oil jet 42 injects oil stored in the oil pan 40 toward the piston 12. The oil pump 44 is configured using, for example, a mechanical pump driven by an engine, and supplies oil sucked from the oil pan 40 to the oil jet 42. The flow control valve 46 is constituted by an electromagnetic valve or the like, and adjusts the amount of oil supplied to the oil jet 42.

  During operation of the engine, the oil pump 44 is driven by the rotation of the crankshaft 16, and oil is supplied from the oil pump 44 to the oil jet 42. Thereby, the oil jet 42 injects oil toward the back surface side of the piston 12, and lubricates and cools the piston 12 and its surrounding parts. Further, when the flow control valve 46 is fully closed, the oil discharged from the oil pump 44 is returned to the suction side via the relief valve 48, and the oil injection of the oil jet 42 is stopped. In the present embodiment, the configuration of the lubrication system as shown in FIG. 1 is exemplified, but the present invention is not limited to the lubrication system.

  Next, a system control system will be described. The system according to the present embodiment includes a sensor system including various sensors necessary for controlling the vehicle and the engine, and an ECU (Electronic Control Unit) 60 that controls the operating state of the engine 10. First, the sensor system will be described. The crank angle sensor 50 outputs a signal synchronized with the rotation of the crankshaft 16, and the air flow sensor 52 detects the intake air amount of the engine. The water temperature sensor 54 detects the water temperature of the engine cooling water, and the in-cylinder pressure sensor 56 detects the in-cylinder pressure. In addition, the sensor system includes, for example, an air-fuel ratio sensor that detects the exhaust air-fuel ratio, a throttle sensor that detects the throttle opening, an intake pressure sensor that detects intake pressure (supercharging pressure), and the amount of accelerator operation by the driver An accelerator sensor or the like for detecting is included.

  The ECU 60 is configured by an arithmetic processing device including a storage circuit such as a ROM and a RAM and an input / output port. Each sensor of the sensor system is connected to the input side of the ECU 60. Various actuators including a throttle valve 22, a fuel injection valve 26, a spark plug 28, a flow control valve 46, and the like are connected to the output side of the ECU 60. The ECU 60 controls the operation of the engine by driving each actuator based on the engine operation information detected by the sensor system. Specifically, the engine speed (engine speed) and the crank angle are detected based on the output of the crank angle sensor 50, and the engine load is detected based on the intake air amount detected by the air flow sensor 52 and the engine speed. Is calculated. Further, the fuel injection amount is calculated based on the engine speed, the engine load, the water temperature, etc., and the fuel injection timing and the ignition timing are determined based on the crank angle. In each cylinder, the fuel injection valve 26 is driven when the fuel injection timing comes, and the spark plug 28 is driven when the ignition timing comes. Thereby, the air-fuel mixture can be burned and the engine can be operated.

  Further, the ECU 60 performs the following air-fuel ratio control and supercharging control. In the air-fuel ratio control, the fuel injection amount is feedback-controlled based on the output of the air-fuel ratio sensor or the like so that the exhaust air-fuel ratio is close to the stoichiometric air-fuel ratio (stoichiometric). In the supercharging control, the opening degree of the waste gate valve 36 is controlled based on the output of the intake pressure sensor or the like so that the supercharging pressure becomes an appropriate magnitude. In the supercharging control, the opening degree of the waste gate valve 36 is controlled so that supercharging is performed in a preset operation region.

[Features of Embodiment 1]
In general, if deposits are attached to the top surface of the piston 12, pre-ignition (self-ignition before ignition) is likely to occur due to the deposit as an ignition source. For this reason, in this Embodiment, when specific driving | running conditions are satisfied, the deposit adhesion suppression control which suppresses that a deposit adheres to the top surface of piston 12, and the pre-ignition suppression control which suppresses generation | occurrence | production of pre-ignition. And is configured to execute. Hereinafter, these controls will be described by taking an engine equipped with a supercharger as an example. The present invention is not limited to an internal combustion engine with a supercharger, but can be widely applied to non-supercharged internal combustion engines.

  FIG. 2 is an explanatory diagram showing an example of an operation region set based on the engine speed and the engine torque and region transition operation in the first embodiment of the present invention. As shown in this figure, the high load low rotation region (shaded portion) in the operation region is set in advance as a pre-ignition region. The pre-ignition region is defined as a region where pre-ignition is easily generated with the deposit attached to the top surface of the piston 12 as an ignition source. Specifically, for example, a region where the engine speed is equal to or lower than a predetermined low rotation determination value and the engine torque is equal to or higher than a predetermined high load determination value can be set as the pre-ignition region. In the following description, the deposit attached to the top surface of the piston 12 and its attached amount are simply referred to as “deposit” and “deposit attached amount”, and the pre-ignition caused by the deposit is simply referred to as “pre-ignition”. Is written. In addition, a region other than the pre-ignition region in the driving region is referred to as a “non-pre-ignition region”.

  In FIG. 2, the region above the boundary line L is a region (oil injection region) where it is necessary to perform lubrication and cooling around the piston by oil injection of the oil jet 42. On the other hand, the region below the boundary line L is a region in which oil injection can be stopped (oil injection stoppable region). Further, the amount of deposit attached to the top surface of the piston 12 has a characteristic that increases particularly in the regions (1) to (6) in FIG. 2, and this property becomes closer to the central region (1). , (1)> (2)> (3)> (4)> (5)> (6).

  In the present embodiment, the deposit adhesion suppression control and the pre-ignition suppression control are executed when an operation in which the engine operating state shifts from the non-pre-ignition region to the pre-ignition region (region transition operation) is performed. An example of the region shift operation is an operation in which the operation state shifts in the order of point A → point B → point C from the low load low rotation region to the high load low rotation region in FIG. In this case, the two suppression controls are executed at a point B where the operation region is switched, for example. Next, the contents and execution timing of deposit adhesion suppression control and pre-ignition suppression control will be described with reference to FIG.

  FIG. 3 is a timing chart showing the engine torque, the piston temperature, and the deposit amount on the piston top surface during the region transition operation in the first embodiment of the present invention. In the present embodiment, pre-ignition suppression control (FIG. 3) is performed at a point B where the operation region is switched when the region transition operation is performed in which the operation state of the engine is shifted from the point A to the point C due to acceleration or the like. (Load limit shown in the upper part) is executed. Preignition suppression control suppresses the occurrence of preignition, for example, by limiting the engine load to a predetermined load upper limit value or less. The load upper limit value is set in advance as the maximum value of the engine load at which the pre-ignition suppression effect is obtained, for example.

  In addition, during the region transition operation, the deposit adhesion suppression control is started almost in synchronization with the start of the pre-ignition suppression control. The deposit adhesion suppression control prohibits the operation of the oil jet 42 and suppresses cooling of the piston 12 due to oil injection. In the present embodiment, as shown in FIG. 3, the oil jet 42 is operated to perform oil injection at a point A included in the non-pre-ignition region (or oil injection stoppable region). For this reason, in the deposit adhesion suppression control, the flow control valve 46 is fully closed and the oil jet 42 is stopped during the region transition operation in which the point A is shifted to the pre-ignition region. The deposit adhesion suppression control prohibits the operation of the oil jet 42 during the region transfer operation regardless of whether the oil jet 42 is operating before the region transfer operation. This point will also be described in a second embodiment described later.

  When the deposit adhesion suppression control is executed, the temperature of the piston 12 rises and the amount of thermal expansion increases as shown in the middle part of FIG. 3, so that the deposit adhering to the top surface of the piston 12 is peeled off from the piston. It burns with the air-fuel mixture in the cylinder or is discharged out of the cylinder. As a result, during the execution period of the pre-ignition suppression control and the deposit adhesion suppression control (for example, during the period in which the operating state is held at the point B), the deposit adhesion amount on the piston top surface is reduced as shown in the lower part of FIG. It gradually decreases. In addition, the one-dot chain line in FIG. 3 exemplifies the piston temperature and the deposit adhesion amount when the oil jet 42 is always operated including during the region transition operation (when the deposit adhesion suppression control is not executed). It can be seen that when the deposit adhesion suppression control is executed, the piston temperature rises and the deposit adhesion amount decreases compared to the one-dot chain line.

  As described above, during the region transition operation, by combining the pre-ignition suppression control and the deposit adhesion suppression control, the oil injection can be stopped and the deposit can be reduced while suppressing the occurrence of the pre-ignition. Therefore, even when the deposit separated from the piston by the deposit adhesion suppression control can be an ignition source, the occurrence of pre-ignition due to this deposit can be suppressed by the pre-ignition suppression control. As a result, it is possible to avoid the occurrence of pre-ignition due to the deposit adhesion suppression control and to proceed with deposit removal stably.

  Moreover, in this Embodiment, it is set as the structure which performs pre-ignition suppression control and deposit adhesion suppression control only for a predetermined | prescribed execution period, and complete | finishes these suppression control after the said execution period passes. The execution period is set, for example, as a period necessary to reduce the deposit adhesion amount to a maximum allowable amount (criteria) or less. Pre-ignition using the deposit on the top surface of the piston as an ignition source occurs when the deposited amount exceeds a certain level, and once generated, it tends to be repeated. For this reason, the criteria are set in advance according to the maximum value of the deposit adhesion amount that can suppress the occurrence (or continuous occurrence) of pre-ignition. Thus, after the execution period has elapsed, the amount of deposit can be reduced to the extent that pre-ignition does not occur, and pre-ignition can be stably suppressed.

  Therefore, when the execution period elapses after the deposit adhesion suppression control is started, as shown in the lower part of FIG. 3, the deposit adhesion amount decreases below the criteria. As a result, after the elapse of the execution period, it becomes difficult for the pre-ignition to repeatedly occur. Therefore, the deposit adhesion suppression control is terminated, the oil injection by the oil jet 42 is started, and the pre-ignition suppression control is terminated. Remove the restriction. In the present invention, it is not always necessary to synchronize these suppression controls. Specifically, a configuration may be adopted in which one of the deposit adhesion suppression control and the pre-ignition suppression control is started first and then the other control is started. Moreover, it is good also as a structure which complete | finishes the other control after ending either one control also at the time of completion | finish of suppression control.

  According to the above control, the pre-ignition suppression control and the deposit adhesion suppression control can be executed only for the necessary minimum execution period to suppress the continuous occurrence of the pre-ignition. Then, after the pre-ignition suppression effect is obtained, these controls can be terminated to return to normal engine control. Thereby, after the completion of the pre-ignition suppression control, the deposit serving as the ignition source is reduced, so that the pre-ignition can be stably suppressed even when the operation is performed in the pre-ignition region. Further, since the length of the execution period can be set to the minimum necessary, the influence of the suppression control on the engine performance and drivability can be minimized.

  Furthermore, the deposit on the piston top surface is reduced by combustion, for example, when the operation is performed in a high load high rotation region. Therefore, even when operating in a low load low rotation region where deposits are likely to adhere, it is not always necessary to execute preignition suppression control and deposit adhesion suppression control when shifting to a high load high rotation region. . For this reason, if it is set as the structure which performs the above-mentioned two suppression control only at the time of the area shift operation which shifts from a low load low rotation area to a high load low rotation area like this embodiment, an extra switching of control is performed. Therefore, drivability can be maintained satisfactorily, and the pre-ignition suppression effect can be maximized at the minimum necessary and accurate timing.

  When the deposit adhesion suppression control is ended (oil injection is started), as shown in FIG. 3, first, intermittent injection for intermittently injecting oil is performed, and then normal oil injection (continuous injection) is performed. It is good also as a structure which transfers. Furthermore, when starting the oil injection, for example, the injection stop state may be shifted to intermittent injection before the execution period elapses, and the continuous injection may be shifted after the execution period elapses. The intermittent injection is realized by intermittently opening the flow control valve 46 from the fully closed state. According to this configuration, the following effects can be obtained. In a state where oil injection is stopped, the temperature of the piston rises to the vicinity of the allowable limit temperature for heat resistance, and it may be necessary to cool the piston. In this case, if intermittent injection is executed, it is possible to protect the piston from being overheated while maintaining the temperature of the piston at a high temperature close to the allowable limit temperature, and it is possible to proceed with the peeling of the deposit in this state.

  Moreover, although the said effect is acquired regardless of the presence or absence of a supercharger, in the engine with a supercharger, the following effect can be acquired further. First, in an engine with a supercharger, pre-ignition is particularly likely to occur when super-charging is performed in a high-load low-rotation region (pre-ignition region). Further, as described above, in the low load and low rotation region, the increase in the amount of deposit is remarkable. Accordingly, as exemplified in the present embodiment, when the region transition operation from the low load low rotation region to the high load low rotation region is performed, the deposit adhesion suppression control and the pre-ignition suppression control are temporarily executed. If so, pre-ignition that occurs during supercharging due to the deposit on the top surface of the piston can be effectively suppressed. In addition, even if the amount of deposit is small in the low load and low rotation area, a pre-ignition tends to occur due to a small amount of deposit in the high load and low rotation area, which is recognized by the driver and is uncomfortable. Is often given. According to the present embodiment, pre-ignition that occurs in such a situation can be efficiently suppressed, and the driver's sense can be maintained well.

[Specific Processing for Realizing Embodiment 1]
Next, a specific process for realizing the above-described control will be described with reference to FIG. FIG. 4 is a flowchart showing an example of control executed by the ECU in the first embodiment of the present invention. The routine shown in this figure is repeatedly executed during operation of the engine. In the routine shown in FIG. 4, first, in step 100, it is determined whether or not the region transition operation is performed. If this determination is not established, this routine is terminated. When the determination in step 100 is established, deposit adhesion suppression control is executed in step 102, and preignition suppression control is executed in step 104.

  Next, in step 106, it is determined whether a predetermined intermittent injection condition is satisfied. As the intermittent injection condition, for example, when the piston temperature estimated based on the intake air amount, fuel injection amount, in-cylinder pressure, exhaust temperature, etc. reaches a predetermined high temperature judgment value (allowable limit temperature, etc.) Examples include a case where a predetermined period has elapsed since the start of the suppression control (stop of oil injection). If the determination in step 106 is established, intermittent oil injection is executed in step 108, and the process proceeds to step 110. If this determination is not established, the process proceeds to step 110 as it is.

  Next, in step 110, it is determined whether or not a predetermined execution period has elapsed since the start of the pre-ignition suppression control and the deposit adhesion suppression control. If this determination is established, the two suppression controls are terminated in steps 112 and 114. On the other hand, if the determination in step 110 is not satisfied, the process returns to step 106, and the processes in steps 106 to 110 are repeated until the determination is satisfied.

  In the first embodiment, step 102 in FIG. 4 shows a specific example of the oil jet control means in claim 1, and step 104 shows a specific example of the preignition suppression means. Moreover, in Embodiment 1, control which restrict | limits an engine load was illustrated as preignition suppression control. However, the present invention is not limited to this, and for example, it may be configured to suppress pre-ignition by control other than load limitation including A / F enrichment control shown in the third embodiment.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that oil injection is stopped in the non-pre-ignition region in the same configuration as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
FIG. 5 is a characteristic diagram showing the relationship between the piston temperature and the deposit amount in the low load to intermediate load region in the second embodiment of the present invention. Note that point P in FIG. 5 corresponds to the state in which oil injection is performed by oil jet 42 in the region (1) where deposits are most likely to adhere in the low load region shown in FIG. Point Q corresponds to a state where oil injection is stopped in region (1). As shown in FIG. 5, when the piston temperature rises, the amount of deposit deposited on the piston top surface tends to decrease rapidly. For this reason, in this Embodiment, it is set as the structure which stops oil injection in the low load-intermediate load area | region where a deposit tends to adhere most.

  For example, when the region transition operation is performed from point A to point C in FIG. 2, the deposit adhesion suppression control and the pre-ignition suppression control are executed for a predetermined execution period as in the first embodiment. In this case, in the deposit adhesion suppression control, the oil jet 42 stopped at the point A included in the region (1) is continued. FIG. 6 is a timing chart showing engine torque, piston temperature, and deposit amount on the top surface of the piston during the region transition operation in the second embodiment of the present invention. As shown in this figure, in the present embodiment, the same control as in the first embodiment is executed except that the oil injection is stopped at the point A.

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. And especially in this Embodiment, before area | region transfer operation is performed, oil injection can be stopped in a low load-intermediate load area | region, and the deposit adhesion amount of a piston top surface can be decreased. Thereby, at the time of area | region transfer driving | operation, the suppression effect of a deposit and a pre-ignition can be heightened further.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. 7 and FIG. The present embodiment is characterized in that A / F enrichment control is adopted as preignition suppression control in the same configuration as in the first or second embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 3]
FIG. 7 is an explanatory diagram showing an example of an engine operation region and region transition operation in Embodiment 3 of the present invention. As shown in this figure, in the present embodiment, in the same manner as in the first embodiment, when the region transition operation in which the operation state is shifted from the point D to the point E is performed, for example, at the point E, the deposit is performed. Adhesion suppression control and preignition suppression control are executed. In the present embodiment, in pre-ignition suppression control, A / F enrichment control is performed to control the exhaust air / fuel ratio to be richer than the stoichiometric air / fuel ratio. As a result, at the point E, the exhaust air-fuel ratio is held at the rich air-fuel ratio during execution of the pre-ignition suppression control, and after the suppression control is finished, the exhaust air-fuel ratio is held at stoichiometric by the air-fuel ratio control. In the above control, the exhaust air-fuel ratio is finally held at the stoichiometric point at the point E. However, in the present invention, the target air-fuel ratio at the point E is not necessarily set to the stoichiometric value. That is, according to the present invention, when the operating state shifts from the point D to the point E, the exhaust air-fuel ratio is controlled to be richer than the target air-fuel ratio at least at the normal time (when the region shift operation is not executed). It ’s good.

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment, and it is possible to suppress pre-ignition by A / F enrichment control. 8 illustrates the case where the A / F enrichment control is performed in the configuration in which the oil injection is stopped in the non-pre-ignition region (Embodiment 2), but the present invention is not limited thereto, and the non-pre-ignition is performed. A / F enrichment control may be applied to a configuration (Embodiment 1) that performs oil injection in a region.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in addition to the same configuration as in any of the first to third embodiments, the execution period is corrected based on the pre-ignition occurrence state after the end of the pre-ignition suppression control. . In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 4]
In the present embodiment, first, after the execution period of deposit adhesion suppression control and pre-ignition suppression control has elapsed (when these suppression control should be terminated), detection parameters that reflect the occurrence state of pre-ignition are acquired. To do. As the detection parameters, various parameters including, for example, in-cylinder pressure and ion current flowing between the electrodes of the spark plug 28 can be considered. When pre-ignition occurs, the in-cylinder pressure increases significantly or the ion current increases as compared with normal combustion. Therefore, the occurrence of pre-ignition can be detected based on this characteristic. In the present embodiment, the case where in-cylinder pressure is used as the detection parameter is exemplified, but the present invention is not limited to this.

  Then, the ECU 60 determines whether or not pre-ignition due to deposit on the piston top surface has occurred, based on information regarding the occurrence frequency of pre-ignition included in the detection parameter. More specifically, when pre-ignition caused by deposits on the top surface of the piston occurs, the pre-ignition occurrence frequency increases in a short period of time, or the pre-ignition occurrence frequency increases. For this reason, the ECU 60 stores in advance an upper limit value of the occurrence frequency per unit time when no pre-ignition occurs, an upper limit value of the continuous occurrence frequency, and the like as determination values. The ECU 60 generates a pre-ignition caused by the deposit on the top surface of the piston when the pre-ignition occurrence frequency or the continuous occurrence frequency calculated based on the detection parameter exceeds the determination value, and the pre-ignition of the pre-ignition is generated. It is determined that the suppression has not been completed.

  If it is determined by the above determination that pre-ignition suppression has not been completed, the execution period is extended, and deposit adhesion suppression control and pre-ignition suppression control are continued. In other words, the execution period is corrected (extended) based on the pre-ignition occurrence state at the time when the suppression control should be terminated. Further, the execution period is corrected so as to coincide with a period in which the deposit amount on the top surface of the piston decreases to an amount that can suppress the occurrence of pre-ignition (continuous firing). In this case, the appropriate correction amount for the execution period is obtained by measurement with an actual machine or the like, and is stored in the ECU 60 in advance.

  After the execution period is corrected, for example, the relationship between the pre-ignition adhesion amount estimated based on the engine operating state and the execution period, or the relationship between the engine operating state and the execution period is stored in map data or the like. May be configured to learn.

[Specific processing for realizing Embodiment 4]
Next, specific processing for realizing the above-described control will be described with reference to FIG. FIG. 9 is a flowchart showing an example of control executed by the ECU in the fourth embodiment of the present invention. As shown in this figure, in the present embodiment, first, in steps 200 to 210, processing similar to that in the first embodiment (FIG. 4) is executed. Next, in step 212, for example, based on the output of the in-cylinder pressure sensor 56, the occurrence of pre-ignition due to the deposit on the top surface of the piston is detected, and it is determined whether or not the suppression of the pre-ignition has been completed. If this determination is not established, pre-ignition suppression has not been completed yet, and after the execution period is extended in step 214, the process returns to step 206. If the determination in step 212 is established, the preignition suppression control and the deposit adhesion suppression control are terminated in steps 216 and 218. Subsequently, in step 220, when the execution period is corrected, the corrected execution period is learned.

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. And according to this Embodiment, even when the deposit more than assumption has adhered to the piston top surface, the execution period of each suppression control can be extended according to this adhesion amount. Therefore, even if the deposit adhesion amount fluctuates, pre-ignition can always be stably suppressed. Further, it is possible to calculate the pre-ignition occurrence frequency and the repetitive frequency based on the detection parameter such as the in-cylinder pressure and selectively detect only the pre-ignition caused by the deposit on the piston top surface based on the calculation result. As a result, the execution period can be extended to an appropriate length without receiving pre-ignition disturbance due to other factors. Furthermore, since the extension result of the execution period can be learned, the execution period can be quickly set to an appropriate length when the next region transfer operation is performed.

  In the fourth embodiment, step 212 shown in FIG. 9 shows a specific example of the pre-ignition detection means in claims 3 and 4, and step 214 shows a specific example of the control period correction means.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, in addition to the same configuration as in any of the first to fourth embodiments, the control in the case where the oil injection is stopped in the low load / low rotation region to the high load region is realized. It is characterized by. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 5]
FIG. 10 is an explanatory diagram showing an example of the engine operation region and region transition operation in the fifth embodiment of the present invention. FIG. 11 is a timing chart showing the engine torque, the engine speed, the piston temperature, and the deposit amount on the piston top surface during the region transition operation. As shown in these drawings, in the present embodiment, a region transition in which the oil injection is stopped in the low load low rotation region (non-preignition region) (point F) to the high load region (point G). When the operation is performed, the following deposit adhesion suppression control is executed.
(1) The oil injection stop state is maintained for a certain period, and intermittent injection of oil is executed after the piston temperature rises to the vicinity of the allowable limit temperature.
(2) Even if intermittent injection is executed, if the cooling of the piston is insufficient, the intermittent injection is shifted to the continuous injection.

  According to the present embodiment, in a low load to intermediate load region where deposits are likely to adhere, oil injection can be stopped to increase the piston temperature, and the deposit amount can be reduced. And after shifting to a high load area | region, a piston can be maintained as high temperature as possible, the deposited deposit can be burned down, and the adhesion amount of a deposit can be reduced.

  In the first to fifth embodiments, the configurations included in the present invention are individually illustrated. However, the present invention is not limited to this, and for example, one of the configurations shown in the first to fifth embodiments can be combined. One system or a plurality of configurations may be combined with each other to form one system.

10 Engine (Internal combustion engine)
12 Piston 14 Combustion chamber 16 Crankshaft 18 Intake passage 20 Exhaust passage 22 Throttle valve 24 Catalyst 26 Fuel injection valve 28 Spark plug 30 Intake valve 32 Exhaust valve 34 Supercharger 36 Wastegate valve 38 Intercooler 40 Oil pan 42 Oil jet 44 Oil pump 46 Flow control valve 48 Relief valve 50 Crank angle sensor 52 Air flow sensor 54 Water temperature sensor 56 In-cylinder pressure sensor 60 ECU

Claims (4)

An oil jet that injects oil toward the piston of the internal combustion engine;
When the region transition operation in which the operation state of the internal combustion engine shifts from the non-pre-ignition region to the pre-ignition region is performed on the basis of the pre-ignition region that is an operation region in which pre-ignition is likely to occur, the oil jet is continuously used. The injection is prohibited, and the continuous injection of oil is started after the execution period set as the period necessary for reducing the amount of deposit adhering to the piston to the maximum allowable amount or less after the prohibition of the continuous injection. Oil jet control means;
Or intermittent injection condition set based on at least one of the temperature and the oil of the injection stop time of the piston has performed an intermittent injection OIL when a condition is satisfied during the execution period, the execution period has elapsed, Or means for stopping the intermittent injection and shifting to continuous oil injection when cooling of the piston by the intermittent injection is insufficient ;
Pre-ignition suppression means for executing suppression control for suppressing pre-ignition when the region transition operation is performed, and terminating the suppression control after the execution period has elapsed;
A control device for an internal combustion engine, comprising: 2. The control of the internal combustion engine according to claim 1, wherein the execution period is set as a minimum period necessary for the amount of deposit attached to the piston to be reduced to an amount capable of suppressing the occurrence of pre-ignition. apparatus. Pre-ignition detection means for detecting occurrence of pre-ignition;
It is determined whether or not suppression of pre-ignition is completed based on a detection result of the pre-ignition detection means, and the execution is performed when it is determined that suppression of pre-ignition is not completed even after the execution period has elapsed. Control period correction means for extending the period and continuing the intermittent injection of oil;
The control device for an internal combustion engine according to claim 1, comprising:   4. The control apparatus for an internal combustion engine according to claim 3, further comprising means for storing and learning the relationship between the execution period extended by the control period correction means and the operating state of the internal combustion engine.

Images