JP2011111921A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine, which enables the stratification combustion and homogeneous combustion, capable of suppressing the deterioration in the operating performance of the internal combustion engine when a knocking is controlled. <P>SOLUTION: An engine system controls the lag amount of ignition timing and the opening timing of an intake valve to a lag side when a knocking is controlled, and controls the injection timing of a cylinder injector to the lag side based on the lag amount. At this time, the fuel pressure of the cylinder injector is regulated to a boost side. Also, the injection ratio of the cylinder injection amount and the injection amount in an intake passage is controlled. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  It is widely known that an internal combustion engine causes abnormal combustion in which the air-fuel mixture in the combustion chamber self-ignites, so-called knocking. Generally, when knocking occurs, control is performed to suppress knocking by retarding the ignition timing of the spark ignition internal combustion engine. It is known that the suppression of knocking by retarding the ignition timing causes deterioration of fuel consumption due to the start of combustion being delayed from an appropriate timing and deterioration of durability of the purification catalyst due to an increase in exhaust temperature. .

  In response to such a problem, when knocking is detected, the ignition timing is retarded quickly to suppress knocking, and the intake valve operating angle and center phase are variably controlled to replace knocking avoidance. Patent Document 1 discloses a technique for suppressing deterioration in fuel consumption associated with knocking avoidance control of an internal combustion engine.

In addition to a port injector that can achieve homogeneous combustion by injecting fuel into an intake port, an internal combustion engine that includes an in-cylinder injector that injects fuel into a combustion chamber is widely known. Such an internal combustion engine can achieve high engine output and low fuel consumption in a wide operating range by controlling the injection ratio of the fuel injection amount from each injector according to the operating state of the engine.
In particular, the in-cylinder injector injects fuel into the combustion chamber during the compression stroke of the internal combustion engine, and forms an air-fuel mixture with good ignitability only in the vicinity of the spark plug at the ignition timing. It is possible to realize a simple combustion of the air-fuel mixture, so-called stratified combustion.

  In such an internal combustion engine, if the ignition timing is retarded in order to suppress knocking, the ignition timing may deviate from the timing at which the fuel injected from the in-cylinder injector flows in the vicinity of the spark plug. As a result, the internal combustion engine may be misfired or exhaust emissions may be deteriorated.

  In response to such a problem, when knocking is detected during the stratified combustion mode operation, the ignition timing is retarded in accordance with the knocking detection level, and in-cylinder injection is performed based on the ignition timing retardation correction amount. Patent Document 2 discloses a technique for suppressing misfire caused by knocking avoidance control and deterioration of exhaust emission by correcting the injection timing of the injector for delay.

  Further, the fuel pressure supplied to the in-cylinder injector is corrected based on the retard correction amount of the in-cylinder injector, and the in-cylinder injector is corrected in accordance with the retard correction of the ignition timing by suppressing knocking. Japanese Patent Application Laid-Open No. 2004-133867 discloses a technique for eliminating the shortage of the actual injection amount of the in-cylinder injector accompanying the increase in the cylinder pressure while suppressing knocking.

JP 2001-336446 A JP 2004-003429 A JP 2002-339788 A

According to such knocking avoidance control, in an internal combustion engine that can realize stratified combustion and homogeneous combustion by including an in-cylinder injector and a port injection injector, the ignition timing and valve timing are retarded, The required values of fuel injection control such as the fuel injection timing of the injector, the fuel pressure and the injection ratio change. However, the technique of Patent Document 1 does not include any means for appropriately executing fuel injection control of each injector when knocking suppression is suppressed in an internal combustion engine capable of realizing stratified combustion and homogeneous combustion. Therefore, there is a problem in that when the knocking is suppressed, the driving performance is deteriorated due to the deterioration of the fuel consumption of the internal combustion engine or the exhaust emission.
In the techniques of Patent Documents 2 and 3, in the fuel injection control of the in-cylinder injector during knocking avoidance control, the ignition timing retardation correction amount and the fuel injection timing retardation correction amount are taken into consideration, respectively. The delay timing correction amount of the valve timing is not taken into consideration. Therefore, there is room for further improvement as means for appropriately executing the fuel injection control of each injector when knocking is suppressed.

  The present invention has been made in view of such a point, and provides an internal combustion engine control device capable of suppressing a decrease in operating performance when knocking is suppressed in an internal combustion engine capable of realizing stratified combustion and homogeneous combustion. With the goal.

In order to achieve the above object, a control apparatus for an internal combustion engine according to the present invention includes variable valve operating means for changing valve timings of intake valves and exhaust valves of each cylinder of the internal combustion engine to desired timings, and combustion of the internal combustion engine. A control device for an internal combustion engine, comprising: a first fuel injection means for injecting and supplying fuel to a chamber; and a second fuel injection means for injecting and supplying fuel to an intake port of the internal combustion engine, wherein each cylinder of the internal combustion engine Knock detection means for detecting the occurrence of knocking, ignition timing control means for controlling the ignition timing of each cylinder of the internal combustion engine to the retard side based on the detection result of the knock detection means, and detection by the knock detection means Based on the result, variable valve control means for controlling the valve opening timing of the intake valve to the retard side by the variable valve means, and ignition timing by the ignition timing control means. Fuel injection timing control means for controlling the fuel injection timing of the first fuel injection means to the retard side based on the retarding amount of the ming and the delay amount of the opening timing of the intake valve by the variable valve control means And.
With the above configuration, when the occurrence of knocking is detected, the fuel injection timing of the first fuel injection means is appropriately retarded based on the retard amount of the ignition timing and the retard amount of the intake valve opening timing. Can be controlled to the side. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.

In particular, the control device for an internal combustion engine of the present invention includes fuel pressure adjusting means for adjusting a pressure of fuel supplied to the first fuel injection means based on an operating state of the internal combustion engine, and the fuel pressure adjusting means includes the fuel pressure adjusting means, Based on the retard amount of the ignition timing by the ignition timing control means and the retard amount of the opening timing of the intake valve by the variable valve control means, the pressure of the fuel supplied to the first fuel injection means is increased to the pressure increasing side. It can be set as the structure to adjust.
With the above configuration, when the occurrence of knocking is detected, the fuel pressure supplied to the first fuel injection means is appropriately increased based on the retard amount of the ignition timing and the retard amount of the intake valve opening timing. It can be adjusted to the pressure side. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.

The control device for an internal combustion engine according to the present invention is configured to inject a fuel amount injected and supplied by the first fuel injection unit and a fuel amount injected and supplied by the second fuel injection unit based on an operating state of the internal combustion engine. An injection division ratio control means for controlling the division ratio, wherein the injection division ratio control means is a retard amount of the ignition timing by the ignition timing control means and a delay in the opening timing of the intake valve by the variable valve control means. Based on the angular amount, it is possible to control the injection ratio of the fuel amount injected and supplied by the first fuel injection means and the fuel amount supplied and supplied by the second fuel injection means.
With the above configuration, when the occurrence of knocking is detected, the fuel of the first fuel injection means and the second fuel injection means is determined based on the retard amount of the ignition timing and the retard amount of the intake valve opening timing. Can be controlled to an appropriate ratio. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.

  According to the control device for an internal combustion engine of the present invention, fuel injection control of the in-cylinder injector and the port injection injector can be appropriately executed when knocking of the internal combustion engine is suppressed. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.

It is the figure which showed one structural example of the engine system of an Example. It is the block diagram which showed schematic structure of the combustion chamber vicinity. An example of knocking avoidance control executed by the engine ECU is shown. The flow of control which engine ECU of an example performs is shown.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of an engine system 1 equipped with a control device for an internal combustion engine of the present invention. FIG. 1 shows only a part of the configuration of the engine.

  An engine system 1 shown in FIG. 1 includes an engine 100 that is a power source, and includes an engine ECU (Electronic Control Unit) 10 that comprehensively controls the operation of the engine 100. The engine system 1 also includes an in-cylinder injector 25 and a port injector 26 in the combustion chamber 11a and the intake port 13, respectively. The engine system 1 includes an electric VVT mechanism 22 and a hydraulic VVT mechanism 23 that change valve timings of the intake valve 18 and the exhaust valve 19. The engine system 1 further includes a knocking sensor 42 that detects the occurrence of knocking in the engine 100.

  The engine 100 is a multi-cylinder engine mounted on a vehicle, and each cylinder includes a piston 11 constituting a combustion chamber 11a. The piston 11 of each combustion chamber is connected to the shaft of the crankshaft 12 that is an output shaft via a connecting rod, and the reciprocating motion of the piston 11 is converted into rotation of the crankshaft 12 by the connecting rod.

  The combustion chamber 11a of each cylinder is provided with an ignition plug 27, and the ignition timing of the ignition plug 27 is adjusted by an igniter 28. The intake air and the mixed gas flowing in from the intake port 13 are mixed with the fuel injected from the in-cylinder injector 25 in the cylinder, and are compressed in the combustion chamber 11 a by the upward movement of the piston 11. The engine ECU 10 determines the ignition timing based on the position of the piston 11 from the crank angle sensor 31 and the cam shaft rotation phase information from the intake cam angle sensor 32 and sends a signal to the igniter 28. The igniter 28 energizes the spark plug 27 with electric power from the battery at the instructed ignition timing in accordance with a signal from the engine ECU 10. The spark plug 27 is ignited by electric power from the battery, ignites the compressed mixed gas, expands the inside of the combustion chamber 11a, and lowers the piston 11. The descending motion is changed to the axial rotation of the crankshaft 12 through the connecting rod, whereby the engine 100 obtains power.

  Connected to the combustion chamber 11a are an intake port 13 communicating with the combustion chamber 11a and an intake passage 14 connected to the intake port 13 and leading intake air from the intake port 13 to the combustion chamber 11a. Further, each cylinder of the combustion chamber 11a is connected to an exhaust port 15 communicating with the combustion chamber 11a and an exhaust passage 16 for guiding the exhaust gas generated in the combustion chamber 11a to the outside of the engine. Further, the exhaust passages 16 connected to the respective cylinders merge on the downstream side to form one merged exhaust passage 17.

When the exhaust valve 19 is opened, the exhaust gas after combustion merges in the merged exhaust passage 17 through the exhaust port 15 and the exhaust passage 16, passes through the purification catalyst 29, and is discharged to the outside of the engine 100. The purification catalyst 29 is used to purify the exhaust gas of the engine 100. For example, a three-way catalyst or a NOx occlusion reduction type catalyst is applied. A plurality of the purification catalysts 29 may be used in combination depending on the displacement of the engine 100, the use area, and the like.
The combined exhaust passage 17 is provided with an exhaust temperature sensor 36, an A / F sensor 37, and an O2 sensor 38, which detects the temperature and air-fuel ratio of the exhaust gas discharged from the combustion chamber 11a, and sends the results to the engine ECU 10. And send. Further, the purification catalyst 29 is provided with a catalyst temperature sensor 40, which detects the temperature of the purification catalyst 29 and transmits the result to the engine ECU 10.

  The piston 11 has a cavity on its top surface. The wall surface of the cavity is formed by a gently curved surface continuous from the direction of the in-cylinder injector 25 to the direction of the spark plug 27, and the fuel injected from the in-cylinder injector 25 is in the vicinity of the spark plug 27 along the wall surface shape. (See FIG. 2). In this case, the piston 11 can form a cavity at an arbitrary position and shape according to the specifications of the engine 100, such as a reentrant combustion chamber in which a cavity is formed in an annular shape at the center of the top surface.

  A crank angle sensor 31 is provided near the axis of the crankshaft 12. The crank angle sensor 31 is configured to detect the rotation angle of the crankshaft 12 axis, and transmits the detection result to the engine ECU 10. Thereby, engine ECU10 acquires the information regarding a crank angle, such as the engine speed at the time of a driving | operation, and rotation angular velocity.

  A plurality of intake valves and exhaust valves are provided corresponding to the intake passage and the exhaust passage of the combustion chamber 11a of each cylinder. FIG. 1 shows one intake passage, one exhaust passage, one intake valve, and one exhaust valve. An intake valve 18 is arranged in each intake port 13 of the combustion chamber 11a, and an intake camshaft 20 for opening and closing the intake valve 18 is arranged. Further, an exhaust valve 19 is disposed at each exhaust port 15 of the combustion chamber 11a, and an exhaust camshaft 21 for opening and closing the exhaust valve 19 is disposed.

  The intake valve 18 and the exhaust valve 19 are opened and closed by the rotation of the intake camshaft 20 and the exhaust camshaft 21 to which the rotation of the crankshaft 12 is transmitted by a coupling mechanism (for example, a timing belt, a timing chain, etc.). 15 and the combustion chamber 11a are communicated and blocked. The phases of the intake valve 18 and the exhaust valve 19 are expressed with reference to the crank angle.

The intake camshaft 20 has an electric VVT mechanism 22 that is a variable valve mechanism (hereinafter referred to as a VVT mechanism). The electric VVT mechanism 22 rotates the intake camshaft 20 with an electric motor in response to an instruction from the engine ECU 10. As a result, the rotational phase of the intake camshaft 20 relative to the crankshaft 12 is changed, so that the valve timing of the intake valve 18 is changed. In this case, the rotation phase of intake camshaft 20 is detected by intake cam angle sensor 32 and output to engine ECU 10. Thereby, the engine ECU 10 can acquire the phase of the intake camshaft 20 and the phase of the intake valve 18. Further, the phase of the intake camshaft 20 is expressed with reference to the crank angle.
The electric VVT mechanism 22 is a configuration example of the variable valve operating means of the present invention.

The exhaust camshaft 21 has a hydraulic VVT mechanism 23. The hydraulic VVT mechanism 23 rotates the exhaust camshaft 21 with an oil control valve (hereinafter referred to as OCV) according to an instruction from the engine ECU 10. As a result, the rotational phase of the exhaust camshaft 21 relative to the crankshaft 12 is changed, so that the valve timing of the exhaust valve 19 is changed. In this case, the rotational phase of the exhaust camshaft 21 is detected by the exhaust cam angle sensor 33 and output to the engine ECU 10. Accordingly, the engine ECU 10 can acquire the phase of the exhaust camshaft 21 and can acquire the phase of the exhaust valve 19. Further, the phase of the exhaust camshaft 21 is expressed with reference to the crank angle.
The hydraulic VVT mechanism 23 is a configuration example of the variable valve operating means of the present invention.

An air flow meter 34, a throttle valve 24, and a throttle position sensor 35 are installed in the intake passage 14 of the engine 100. The air flow meter 34 and the throttle position sensor 35 detect the amount of intake air passing through the intake passage 14 and the opening of the throttle valve 24, respectively, and transmit the detection results to the engine ECU 10. The engine ECU 10 recognizes the amount of intake air introduced into the intake port 13 and the combustion chamber 11a based on the transmitted detection result, and adjusts the opening of the throttle valve 24 to thereby adjust the intake air necessary for the operation of the engine 100. Is taken into the combustion chamber 11a.
The throttle valve 24 preferably employs a throttle-by-wire system using a step motor. For example, the opening of the throttle valve 24 is changed in conjunction with an accelerator pedal (not shown) via a wire instead of a step motor. A mechanical throttle mechanism as described above can also be applied.

  An in-cylinder injector 25 and a port injector 26 are attached to the combustion chamber 11a and the intake port 13 (see FIG. 2). The fuel supplied from the high-pressure fuel pump 30 through the fuel pipe is injected and supplied to the combustion chamber 11a in the engine cylinder by the in-cylinder injector 25 according to an instruction from the engine ECU 10. Further, fuel supplied from a low-pressure fuel pump (not shown) through the fuel pipe is injected and supplied to the intake port 13 by the port injector 26 according to an instruction from the engine ECU 10. The engine ECU 10 determines the fuel injection amount and the injection timing based on the intake air amount from the air flow meter 34 and the throttle position sensor 35 and the cam shaft rotation phase information from the intake cam angle sensor 32, and determines the in-cylinder injector 25, port A signal is sent to the injector 26. In-cylinder injector 25 and port injector 26 inject high-pressure fuel into combustion chamber 11a and intake port 13 at the instructed fuel injection amount / injection timing in accordance with a signal from engine ECU 10. The leaked fuel from the in-cylinder injector 25 and the port injector 26 is returned to a fuel tank (not shown) through a relief pipe. In this case, a configuration may be adopted in which a high-pressure fuel is supplied to the in-cylinder injector 25 by providing a pressure accumulating chamber between the high-pressure fuel pump 30 and the in-cylinder injector 25. Further, the fuel may be supplied to the in-cylinder injector 25 and the port injector 26 from the same fuel pump.

The high-pressure fuel pump 30 includes a cylinder and a plunger that reciprocates within the cylinder. The high-pressure fuel pump 30 is drivingly connected to the intake camshaft 20 synchronized with the rotation of the engine 100, and the internal plunger reciprocates by the rotational drive of the intake camshaft 20, thereby discharging high-pressure fuel. The high-pressure fuel pump 30 adjusts the pressure of the fuel supplied to the in-cylinder injector 25 to a desired pressure by adjusting the fuel discharge pressure based on an instruction from the engine ECU 10. In this case, by providing a known pressure regulating valve (relief valve) such as a solenoid type in the middle of the relief pipe communicating with the in-cylinder injector 25, the pressure of the fuel supplied to the in-cylinder injector 25 is adjusted. Also good.
The high-pressure fuel pump 30 is a configuration example of the fuel pressure adjusting means of the present invention.

The in-cylinder injector 25 is attached to the combustion chamber 11a below the intake port 13 in an oblique direction. In-cylinder injector 25 injects fuel into combustion chamber 11a at a predetermined timing in the compression stroke of engine 100 based on an instruction from engine ECU 10. The fuel injected at high pressure atomizes and enters the cavity of the piston 11 and is guided to the vicinity of the spark plug 27 along the shape of the cavity. Then, it is mixed with the intake air supplied when the intake valve 18 is opened during flight, and a mixed gas suitable for combustion of the engine 100 is formed only in the vicinity of the ignition plug 27 at the ignition timing. Realizes combustion of a lean air-fuel mixture, so-called stratified combustion (see FIG. 2). In this case, the in-cylinder injector 25 is not limited to the lower portion of the intake port 13 and can be mounted at any position where stratified combustion can be realized.
The in-cylinder injector 25 is a structural example of the first fuel injection means of the present invention.

  A fuel pressure sensor 41 is provided in the fuel piping of the in-cylinder injector 25. The fuel pressure sensor 41 detects the pressure of the fuel supplied to the in-cylinder injector 25 and transmits the detection result to the engine ECU 10. The engine ECU 10 recognizes the pressure of the fuel supplied to the in-cylinder injector 25 based on the transmitted detection result. The fuel pressure sensor 41 can be provided at any part capable of detecting the pressure of the fuel supplied to the in-cylinder injector 25 regardless of the fuel piping.

The port injector 26 injects fuel into the intake port 13 at a predetermined timing in the intake stroke of the engine 100 based on an instruction from the engine ECU 10. The high pressure injected fuel is atomized and mixed with the intake air, and becomes a mixed gas suitable for combustion of the engine 100. Then, by supplying the mixed gas to the combustion chamber 11a when the intake valve 18 is opened, so-called homogeneous combustion is realized in which the entire combustion chamber is combusted with the same air-fuel ratio (see FIG. 2).
The port injector 26 is a structural example of the second fuel injection means of the present invention.

A knocking sensor 42 is provided in each cylinder of the engine 100. The knocking sensor 42 generates an electromotive force in response to a pressure change in the combustion chamber and a knocking vibration frequency, and transmits the signal to the engine ECU 10. Engine ECU 10 determines whether or not knocking has occurred in engine 100 based on a signal from knocking sensor 42. In this case, a configuration may be adopted in which knocking of engine 100 is detected by providing a vibration sensor such as a vibration-type angular velocity sensor.
The knocking sensor 42 is a configuration example of the knocking detection unit of the present invention.

  The engine ECU 10 includes a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) and NVRAM (Non Volatile RAM) that store data and the like. Computer. The engine ECU 10 reads the detection results of the crank angle sensor 31, the intake cam angle sensor 32, the air flow meter 34, the throttle position sensor 35, the exhaust temperature sensor 36, the water temperature sensor 39, etc., and operates the throttle valve 24, the intake valve 18, and the exhaust gas. The operation operation of the engine 100 such as the operation of the valve 19, the operation of the in-cylinder injector 25 and the port injector 26, the ignition timing of the spark plug 27, etc. are integratedly controlled.

Further, the engine ECU 10 controls the injection ratio between the amount of fuel injected and supplied by the in-cylinder injector 25 and the amount of fuel supplied and supplied by the port injector 26 based on the operating state of the engine 100, and is supplied to the in-cylinder injector 25. Adjust the fuel pressure.
For example, when the engine 100 is operating at a low speed and a low load, the engine ECU 10 instructs the in-cylinder injector 25 to inject fuel and directly injects fuel into the combustion chamber 11a to execute stratified combustion. Further, for example, when the engine speed exceeds a predetermined value, the engine ECU 10 instructs the port injector 26 to inject fuel and injects fuel into the intake port 13 to execute homogeneous combustion or direct injection. And weakly stratified combustion using both port injection. The injection ratio between the in-cylinder injector 25 and the port injector 26 is set to an appropriate value obtained by a bench test or the like and stored in advance in the ROM of the engine ECU 10.
In this case, the engine ECU 10 instructs the high-pressure fuel pump 30 based on the operating state of the engine 100 and the signal from the fuel pressure sensor 41 to adjust the fuel pressure supplied to the in-cylinder injector 25 to the target fuel pressure.

  The engine ECU 10 controls the fuel injection timing of the in-cylinder injector 25 to an appropriate injection timing based on knocking avoidance control when knocking suppression of the engine 100 is suppressed, and the fuel pressure supplied to the in-cylinder injector 25 is appropriately set. Adjust to pressure. Further, the engine ECU 10 controls the fuel injection ratio of the in-cylinder injector 25 and the port injector 26 to an appropriate ratio.

  When engine ECU 10 determines that knocking has occurred in engine 100 based on the detection result of knocking sensor 42, engine ECU 10 executes knocking avoidance control. Specifically, engine ECU 10 recognizes the detection level of knocking of engine 100 from the signal of knocking sensor 42. Based on the recognized knocking detection level, the engine ECU 10 (1) retards the ignition timing (see FIG. 3A), and (2) retards the valve opening timing of the intake valve 18 (FIG. 3). (See (b)). Based on the calculated (1) and (2), the engine ECU 10 instructs the igniter 28 and the electric VVT mechanism 22 to retard the ignition timing of the spark plug 27 and the opening timing of the intake valve 18. In this case, as the knocking avoidance control of (1) and (2), a technique equivalent to the conventional knocking avoidance control method of the internal combustion engine can be applied.

Based on the calculated (1) retard amount of the ignition timing and (2) retard amount of the valve opening timing of the intake valve 18 with the start of knocking avoidance control, the engine ECU 10 obtains the following equation (3): The retardation amount of the fuel injection timing of the in-cylinder injector 25 is calculated.
Δainjd = ΔSA + ΔinVVT (3)
(Δainjd: retard amount of fuel injection timing, ΔSA: retard amount of ignition timing, ΔinVVT: retard amount of intake valve opening timing)
Subsequently, the engine ECU 10 calculates the target injection timing of the in-cylinder injector 25 based on the following equation (4), and instructs the in-cylinder injector 25 to control the fuel injection timing to the target injection timing.
ainjd ′ = ainjd + Δainjd (4)
(Ainjd ′: target injection timing, ainjd: fuel injection timing before control)

  When the ignition timing and intake valve opening timing are retarded in accordance with knocking avoidance control, the in-cylinder injector injects fuel later in the compression stroke in order to properly burn the fuel injected into the combustion chamber. It is required to do. That is, the target fuel injection timing into the combustion chamber changes to the retard side. For this reason, when knocking is suppressed, the fuel injection timing of the in-cylinder injector is different from the target injection timing, which may cause a decrease in the operating performance of the internal combustion engine. Therefore, by executing the above control, the target injection timing is calculated from the retard amount of the ignition timing at the time of knocking suppression and the valve opening timing of the intake valve, and the fuel of the in-cylinder injector 25 is based on the calculated target injection timing. The injection timing can be appropriately controlled. Therefore, it is possible to suppress a decrease in the operating performance of the internal combustion engine when knocking is suppressed.

Further, the engine ECU 10 performs the following (5) based on the calculated (1) retard amount of the ignition timing and (2) retard amount of the valve opening timing of the intake valve 18 with the start of the knocking avoidance control. The adjustment amount of the fuel pressure of the in-cylinder injector 25 is calculated from the equation.
Δepr = (ΔSA + ΔinVVT) × Kepr (5)
(Δepr: fuel pressure adjustment amount, ΔSA: ignition timing retardation amount, ΔinVVT: intake valve opening timing retardation amount, Kepr: conversion coefficient to fuel pressure)
Here, the fuel pressure conversion coefficient (Kepr) is a coefficient determined by the model of the engine 100 and the like, is set to an appropriate value obtained by a bench test or the like, and is stored in advance in the ROM of the engine ECU 10. The
Subsequently, the engine ECU 10 calculates the target fuel pressure of the fuel supplied to the in-cylinder injector 25 based on the following equation (6), and instructs the high-pressure fuel pump 30 to adjust the fuel pressure to the target fuel pressure.
epr ′ = epr + Δepr (6)
(Epr ': target fuel pressure, epr: fuel pressure before adjustment)

  When the ignition timing and the intake valve opening timing are retarded in accordance with the knocking avoidance control, the in-cylinder injector is required to inject fuel into the combustion chamber later in the compression stroke. That is, fuel is injected into the combustion chamber against a higher in-cylinder pressure, and the differential pressure between the fuel pressure supplied to the in-cylinder injector and the in-cylinder pressure is further reduced. Therefore, when the knocking is suppressed, the pressure of the fuel supplied to the in-cylinder injector is not sufficient, so that the fuel injection amount per unit time of the in-cylinder injector decreases, resulting in a decrease in the operating performance of the internal combustion engine. There is. Therefore, by executing the above-described control, the cylinder pressure is recognized from the retard amount of the ignition timing at the time of knocking suppression and the valve opening timing of the intake valve, and the fuel supplied to the cylinder injector 25 based on the recognized cylinder pressure. Can be increased and adjusted to an appropriate fuel pressure. Therefore, it is possible to suppress a decrease in the operating performance of the internal combustion engine when knocking is suppressed.

Furthermore, the engine ECU 10 performs the following (7) based on the calculated (1) retard amount of the ignition timing and (2) the retard amount of the valve opening timing of the intake valve 18 with the start of the knocking avoidance control. The adjustment amount of the fuel injection ratio of the in-cylinder injector 25 and the port injector 26 is calculated from the equation.
Δkpfi = (ΔSA + ΔinVVT) × Kkpfi (7)
(Δkpfi: adjustment amount of injection division ratio, ΔSA: retardation amount of ignition timing, ΔinVVT: retardation amount of opening timing of intake valve, Kkpfi: conversion coefficient to injection division ratio)
Here, the conversion coefficient (Kkpfi) to the injection ratio is a coefficient determined by the model of the engine 100 and the like, set to an appropriate value obtained by a bench test or the like, and stored in advance in the ROM of the engine ECU 10. Is done.
Subsequently, the engine ECU 10 calculates a target fuel injection ratio between the in-cylinder injector 25 and the port injector 26 based on the following equation (8), and instructs the in-cylinder injector 25 and the port injector 26 to perform the injection separation. Control the ratio to the target ratio.
kpfi ′ = kpfi + Δkpfi (8)
(Kpfi ': target injection ratio, kpfi: injection ratio before control)

  If the ignition timing and the intake valve opening timing are retarded in accordance with the knocking avoidance control, the in-cylinder injector and the port injector are required to inject fuel at the later stage of the compression stroke. That is, since the fuel injection timing into the combustion chamber and the intake port changes, the fuel injection ratio of the target injector also changes accordingly. For this reason, when knocking is suppressed, the fuel injection ratio of the in-cylinder injector and the port injector is different from the target ratio, which may cause a decrease in operating performance due to deterioration of fuel consumption or exhaust emission of the internal combustion engine. Therefore, by executing the above control, the fuel target injection ratio is calculated from the retard amount of the ignition timing at the time of knocking suppression and the valve opening timing of the intake valve, and the in-cylinder injector 25 is based on the calculated target ratio. And the port injector 26 can be appropriately controlled. Therefore, it is possible to suppress a decrease in the operating performance of the internal combustion engine when knocking is suppressed.

In this case, the engine ECU 10 controls the fuel injection timing of the in-cylinder injector 25, adjusts the fuel pressure of the in-cylinder injector 25, and the injection ratio between the in-cylinder injector 25 and the port injector 26 based on the operating state of the engine 100. It is also possible to execute at least one of the following controls. Further, the engine ECU 10 determines the fuel pressure of the in-cylinder injector 25 using the retard amount of the fuel injection timing of the in-cylinder injector 25 calculated from the equation (3) instead of (1) the retard amount of the ignition timing. The adjustment amount and the adjustment amount of the injection ratio of the in-cylinder injector 25 and the port injector 26 may be calculated.
The engine ECU 10 is a configuration example of the fuel pressure adjusting unit and the injection ratio control unit of the present invention.

  Next, the operation of the engine system 1 will be described along the control flow of the engine ECU 10. FIG. 4 is a flowchart showing an example of processing of the engine ECU 10. The engine system 1 of the present embodiment includes variable valve means, first fuel injection means, second fuel injection means, knocking detection means, fuel pressure adjustment means, and injection ratio control means. At the time of suppressing knocking of the engine 100, control of the fuel injection timing of the in-cylinder injector 25, adjustment of the fuel pressure of the in-cylinder injector 25, and control of the injection ratio between the in-cylinder injector 25 and the port injector 26 are executed.

  The control of the engine ECU 10 starts when the engine 100 is requested to start, that is, when the ignition switch is turned on, and the following control is repeated until the engine 100 is requested to stop. First, in step S1, the engine ECU 10 determines whether or not knocking has occurred in the engine 100 based on the detection result of the knocking sensor 42. If knocking has not occurred (step S1 / NO), the engine ECU 10 ends the control process. If knocking has occurred (step S1 / YES), the engine ECU 10 proceeds to the next step S2.

  In step S2, engine ECU 10 recognizes the detection level of knocking of engine 100 from the signal of knocking sensor 42 detected in step S1. Then, the engine ECU 10 determines the retard amount of the ignition timing (see FIG. 3A) and the retard amount of the opening timing of the intake valve 18 based on the recognized knocking detection level (see FIG. 3B). Is calculated. When the engine ECU 10 finishes the process of step S2, the process proceeds to the next step S3.

  In step S3, the engine ECU 10 calculates the target injection timing of the in-cylinder injector 25 from the equations (3) and (4) based on the respective retard amounts calculated in step S3. Further, the engine ECU 10 calculates the target fuel pressure of the in-cylinder injector 25 from the equations (5) and (6) based on the respective retard amounts calculated in step S3. Further, the engine ECU 10 calculates the target fuel injection ratio of the in-cylinder injector 25 and the port injector 26 from the equations (7) and (8) based on the respective retard amounts calculated in step S3. After finishing the process of step S3, the engine ECU 10 proceeds to the next step S4.

In step S4, the engine ECU 10 instructs the in-cylinder injector 25 to control the fuel injection timing to the target injection timing based on the target injection timing calculated in step S3. Further, the engine ECU 10 instructs the high-pressure fuel pump 30 to adjust the fuel pressure to the target fuel pressure based on the target fuel pressure calculated in step S3. Further, the engine ECU 10 instructs the in-cylinder injector 25 and the port injector 26 based on the fuel target injection ratio calculated in step S3 to control the injection ratio to the target ratio.
By executing this control, the fuel injection control of the in-cylinder injector 25 and the port injector 26 can be appropriately executed when knocking of the engine 100 is suppressed. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.
The engine ECU 10 ends the control process when the process of step S4 is completed.

  As described above, the engine system of the present embodiment retards the fuel injection timing of the in-cylinder injector based on the retard amount of the ignition timing and the retard amount of the intake valve opening timing when suppressing engine knocking. In-cylinder injector when controlling the knocking of the internal combustion engine by adjusting the pressure of the fuel supplied to the in-cylinder injector to the pressure increasing side and appropriately controlling the injection ratio between the in-cylinder injector and the port injector In addition, the fuel injection control of the port injector can be appropriately executed. Therefore, it is possible to suppress a decrease in operating performance when knocking is suppressed in an internal combustion engine that can realize stratified combustion and homogeneous combustion.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

1 Engine system 10 Engine ECU (fuel pressure adjusting means, injection ratio control means)
11 Piston 11a Combustion chamber 13 Intake port 18 Intake valve 22 Electric VVT mechanism (variable valve operating means)
23 Hydraulic VVT mechanism (variable valve operating means)
25 In-cylinder injector (first fuel injection means)
26 Port injector (second fuel injection means)
27 Spark plug 30 High-pressure fuel pump (fuel pressure adjusting means)
41 Fuel pressure sensor 42 Knocking sensor (knocking detection means)
100 engine

Claims (3)

Variable valve means for changing the valve timings of the intake and exhaust valves of each cylinder of the internal combustion engine to desired timings; first fuel injection means for injecting fuel into the combustion chamber of the internal combustion engine; and A second fuel injection means for injecting and supplying fuel to the intake port,
Knocking detecting means for detecting occurrence of knocking in each cylinder of the internal combustion engine;
Ignition timing control means for controlling the ignition timing of each cylinder of the internal combustion engine to the retard side based on the detection result of the knocking detection means;
Variable valve control means for controlling the valve opening timing of the intake valve to the retard side by the variable valve means based on the detection result of the knocking detection means;
Based on the retard amount of the ignition timing by the ignition timing control means and the retard amount of the opening timing of the intake valve by the variable valve control means, the fuel injection timing of the first fuel injection means is retarded. Fuel injection timing control means to control;
A control device for an internal combustion engine, comprising: Fuel pressure adjusting means for adjusting the pressure of the fuel supplied to the first fuel injection means based on the operating state of the internal combustion engine;
The fuel pressure adjusting means supplies to the first fuel injection means based on the retard amount of the ignition timing by the ignition timing control means and the retard amount of the opening timing of the intake valve by the variable valve control means. 2. The control apparatus for an internal combustion engine according to claim 1, wherein the pressure of the fuel is adjusted to the pressure increasing side. There is provided an injection ratio control means for controlling an injection ratio between the amount of fuel injected and supplied by the first fuel injection means and the amount of fuel supplied and supplied by the second fuel injection means based on the operating state of the internal combustion engine. ,
The injection split ratio control means is configured such that the first fuel injection means is based on a retard amount of the ignition timing by the ignition timing control means and a retard amount of the opening timing of the intake valve by the variable valve control means. 3. The control apparatus for an internal combustion engine according to claim 1, wherein an injection ratio between a fuel amount to be injected and a fuel amount to be injected and supplied by the second fuel injection means is controlled.

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