JP2006057514A - Control device for cylinder injection spark ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely inject a required amount of fuel from each fuel injection valve during compression-stroke fuel injection when starting an engine. <P>SOLUTION: This control device for a cylinder injection spark ignition internal combustion engine determines a valve opening time for the fuel injection valve in each cylinder during compression-stroke fuel injection when starting the engine, in accordance with a required amount of fuel and fuel pressure in an accumulator. It estimates fuel pressure in the accumulator during fuel injection in accordance with the fuel pressure in the accumulator when determining the valve opening time (Steps 103, 106), and determines the valve opening time using the estimated fuel pressure in the accumulator during the fuel injection (Step 107). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an in-cylinder injection spark ignition internal combustion engine.

  At the time of starting the engine, it is desired to quickly warm up the catalyst device arranged in the engine exhaust system and to purify the exhaust gas immediately after the engine is started. Therefore, in general, the exhaust gas temperature is raised by retarding the ignition timing. In a cylinder injection type spark ignition internal combustion engine, it has been proposed to inject fuel in the compression stroke at the time of starting the engine and concentrate the fuel in the vicinity of the spark plug (see, for example, Patent Document 1). By concentrating the fuel in the vicinity of the spark plug in this way, ignitability is ensured with respect to the retard of the ignition timing, thereby enabling a significant retard of the ignition timing at the start of the engine and the exhaust gas temperature. Can be increased sufficiently.

  By the way, an in-cylinder spark ignition internal combustion engine generally has a pressure accumulation chamber common to each cylinder, and pressurized fuel in the pressure accumulation chamber is injected via a fuel injection valve of each cylinder. The fuel in the pressure accumulating chamber is generally pressurized by an engine-driven high pressure pump.

JP 2002-38993 A

  In the compression stroke fuel injection at the time of starting the engine, the valve opening time of each fuel injection valve must be determined based on the required fuel amount and the fuel pressure in the pressure accumulating chamber. However, especially when the engine speed is increasing at the initial stage of engine startup, the fuel pressure in the pressure accumulating chamber is being gradually increased by the high-pressure pump, and the timing for determining the valve opening time and the actual fuel injection timing Because the fuel pressure in the pressure accumulating chamber is relatively different, the required amount of fuel may not be injected into the cylinder even if the fuel injection valve is opened based on the determined valve opening time. If more fuel is injected than is necessary, fuel consumption will be worsened.

  Accordingly, an object of the present invention is to provide a control device for a direct injection spark ignition internal combustion engine that can reliably inject a required amount of fuel by each fuel injection valve at the time of compression stroke fuel injection at the time of engine start. .

  According to a first aspect of the present invention, there is provided a control device for an in-cylinder injection spark ignition internal combustion engine, wherein the opening time of the fuel injection valve of each cylinder at the time of compression stroke fuel injection at the time of engine start is determined according to the required fuel amount and the pressure accumulation chamber. In the control device for a cylinder injection spark ignition internal combustion engine that is determined based on the fuel pressure, the fuel pressure in the pressure accumulating chamber at the time of fuel injection is estimated based on the fuel pressure in the pressure accumulating chamber at the time of determining the valve opening time. The valve opening time is determined using the fuel pressure in the pressure accumulating chamber at the time of fuel injection.

  According to a second aspect of the present invention, there is provided a control device for a direct injection spark ignition internal combustion engine according to the first aspect of the present invention, wherein the valve opening time is determined in the control device for the direct injection spark ignition internal combustion engine according to the first aspect. When there is fuel pumping to the accumulator chamber from the time of fuel injection to the time of fuel injection, the fuel pressure increase in the accumulator chamber due to the previous fuel pumping is added to the fuel pressure at the time of determining the valve opening time, and when the valve opening time is determined The fuel pressure in the pressure accumulating chamber at the time of fuel injection is estimated.

  According to a third aspect of the present invention, there is provided a control device for a direct injection spark ignition internal combustion engine according to the third aspect of the present invention, wherein the valve opening time is determined in the control device for the direct injection spark ignition internal combustion engine according to the second aspect. When there is fuel injection to the other cylinder from the time of fuel injection to the time of fuel injection, the fuel pressure drop in the pressure accumulation chamber due to fuel injection to the other cylinder is subtracted from the fuel pressure at the time of determining the valve opening time, and the valve opening time The fuel pressure in the pressure accumulating chamber at the time of fuel injection is estimated at the time of determination.

  In addition, the control device for a direct injection spark ignition internal combustion engine according to claim 4 according to the present invention is the control device for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 3, When the closing timing of the fuel injection valve based on the determined valve opening time becomes later than the ignition timing, the ignition timing is retarded to make the closing timing of the fuel injection valve earlier than the ignition timing.

  A control device for a direct injection spark ignition internal combustion engine according to claim 5 of the present invention is the control device for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 3, When the closing timing of the fuel injection valve based on the determined opening time is later than the ignition timing, the opening timing of the fuel injection valve is advanced to make the closing timing of the fuel injection valve earlier than the ignition timing. It is characterized by.

  According to the control device for a cylinder injection spark ignition internal combustion engine according to claim 1 of the present invention, the opening time of the fuel injection valve of each cylinder at the time of the compression stroke fuel injection at the time of engine start is determined as the required fuel amount and the accumulated pressure. The fuel pressure in the pressure accumulating chamber at the time of fuel injection is estimated based on the fuel pressure in the pressure accumulating chamber at the time of determining the valve opening time, and the estimated fuel pressure in the pressure accumulating chamber at the time of fuel injection is determined Is used to determine the valve opening time, so even if the fuel pressure in the pressure accumulating chamber differs between the time of determining the valve opening time and the time of fuel injection, the exact valve opening time for injecting the required amount of fuel The required fuel amount can be reliably injected in the compression stroke.

  According to the control device for a direct injection spark ignition internal combustion engine according to claim 2 according to the present invention, in the control device for the direct injection spark ignition internal combustion engine according to claim 1, the valve opening time is determined. When there is fuel pumping to the accumulator chamber from the time of fuel injection to the time of fuel injection, it is assumed that the fuel pressure increase in the unknown accumulator chamber for this fuel pumping is almost the same as the known fuel pressure increase by the previous fuel pumping A known fuel pressure increase is added to the fuel pressure at the time of determining the valve opening time, and the fuel pressure in the pressure accumulating chamber at the time of fuel injection can be estimated relatively accurately at the time of determining the valve opening time. .

  According to the control device for a direct injection spark ignition internal combustion engine according to claim 3 of the present invention, in the control device for the direct injection spark ignition internal combustion engine according to claim 2, the valve opening time is determined. When there is fuel injection into other cylinders from the time to the time of fuel injection, the fuel pressure drop in the pressure accumulating chamber due to fuel injection into the other cylinders has already been determined and can be accurately estimated In addition, by subtracting this from the fuel pressure at the time of determining the valve opening time, the fuel pressure in the pressure accumulating chamber at the time of fuel injection can be accurately estimated at the time of determining the valve opening time of the corresponding cylinder.

  According to the control device for a direct injection spark ignition internal combustion engine according to claim 4 according to the present invention, in the control device for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 3, When the closing timing of the fuel injection valve based on the determined opening time becomes later than the ignition timing, the ignition timing is retarded so that the closing timing of the fuel injection valve is earlier than the ignition timing. Thus, it is possible to prevent the fuel injection and the misfire from occurring even at the ignition timing.

  According to the control device for a direct injection spark ignition internal combustion engine according to claim 5 of the present invention, in the control device for a direct injection spark ignition internal combustion engine according to any one of claims 1 to 3, When the closing timing of the fuel injection valve based on the determined opening time is later than the ignition timing, the opening timing of the fuel injection valve is advanced so that the closing timing of the fuel injection valve is earlier than the ignition timing. Thus, fuel injection is still performed even at the ignition timing, and misfires are prevented from occurring.

  FIG. 1 is a schematic view of a direct injection spark ignition internal combustion engine to which a control device according to the present invention is attached. In the figure, reference numeral 1 denotes, for example, a 4-cylinder engine body. However, the number of cylinders does not limit the present invention, and the present invention can be applied to an in-cylinder injection spark ignition internal combustion engine having an arbitrary number of cylinders. 2 is a spark plug, and 3 is a fuel injection valve for directly injecting fuel into each cylinder. Reference numeral 4 denotes a pressure accumulating chamber for supplying fuel to each fuel injection valve 3. The fuel in the fuel tank 7 is pressurized and supplied to the pressure accumulating chamber 4 via the low pressure pump 6 and the high pressure pump 5. The low-pressure pump 6 is electrically driven, and the pressure of the fuel sucked into the high-pressure pump 5 is increased to, for example, 0.4 MPa to prevent the generation of vapor. The high-pressure pump 5 is an engine-driven type, and finally boosts the fuel in the pressure accumulation chamber 4 to, for example, 13 MPa. In the pressure accumulating chamber 4, a pressure sensor 4a for detecting the fuel pressure is arranged.

  The in-cylinder spark-ignition internal combustion engine can suppress deterioration in fuel consumption because a required amount of fuel is reliably supplied into the cylinder. During normal operation, homogeneous combustion is performed in which a homogeneous mixture is formed in the cylinder by fuel injection in the intake stroke. Of course, stratified combustion with a lean air-fuel ratio may be performed as a whole in the cylinder that combusts the air-fuel mixture in the vicinity of the spark plug by fuel injection in the compression stroke.

  By the way, when the engine is started, it is desired to quickly warm up the catalyst device disposed in the engine exhaust system and to purify the exhaust gas immediately after the engine is started. For this purpose, it is preferable to retard the ignition timing at the time of starting the engine and raise the temperature of the exhaust gas. In order to ensure ignitability with respect to the retarded ignition timing, the air-fuel ratio in the vicinity of the spark plug 2 must be made richer than the stoichiometric air-fuel ratio. Therefore, a relatively large amount of fuel is required. On the other hand, for example, even if the air-fuel ratio in the entire cylinder is the stoichiometric air-fuel ratio, if a rich air-fuel ratio mixture is formed only in the vicinity of the spark plug 2 by compression stroke injection, a large amount of fuel is generated. The ignitability is ensured without necessity, and the ignition timing can be greatly retarded, so that the exhaust gas temperature can be sufficiently increased.

  Thus, in the present embodiment, when the engine is started, the fuel is injected in the compression stroke because of a large retardation of the ignition timing. FIG. 2 is a time chart showing a change in the fuel pressure in the pressure accumulating chamber 4 in the initial stage of engine starting, that is, during cranking and immediately after the engine speed is increased. The above-described high-pressure pump 5 discharges fuel to the pressure accumulation chamber 4 during the compression stroke of the # 1 cylinder and # 3 cylinder, for example. The ignition order in the above-described four-cylinder in-cylinder spark ignition internal combustion engine is, for example, # 1- # 4- # 3- # 2. In FIG. 2, the numbers (# 1, # 2, # 3, # 4) indicating each cylinder indicate the compression top dead center of each cylinder.

  The fuel pressure P in the pressure accumulating chamber 4 is increased stepwise by the fuel discharge of the high-pressure pump 5 by cranking, and if it becomes a set value P1 (for example, 3 MPa) or more, fuel injection in the compression stroke becomes possible. The valve opening time for injecting the required fuel amount in each fuel injection valve 3 at the time of the compression stroke fuel injection is not determined in time for fuel injection valve opening / closing control even if it is calculated at the time of fuel injection, and is determined in advance during the intake stroke, for example. It is preferable to keep it.

  The valve opening time of the fuel injection valve 3 is determined based on the required fuel amount and the fuel injection pressure. That is, the valve opening time is shorter as the required fuel amount is smaller, and is shorter as the fuel injection pressure is higher. By the way, if the fuel injection pressure is high, the frictional force between the injected fuel and the intake air in the cylinder is increased, and atomization of the injected fuel is promoted. Can be improved. Thereby, the required fuel amount can be reduced as the fuel injection pressure is higher. Thus, in order to determine the valve opening time of the fuel injection valve 3, the fuel injection pressure, that is, the fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection is required.

  However, the fuel pressure in the pressure accumulating chamber 4 changes relatively greatly between the determination of the valve opening time of the fuel injection valve 3 and the actual fuel injection, especially during the increase in the engine speed at the initial stage of engine startup. Even if the valve opening time is determined by using the fuel pressure in the pressure accumulating chamber 4 measured at the time of determining the valve opening time, the valve opening time is not accurate, and the injected fuel is insufficient for the required fuel amount. In some cases, misfire may occur, and if the amount of injected fuel is excessive with respect to the required amount of fuel, fuel consumption is deteriorated or the amount of unburned fuel discharged is increased.

  In the present embodiment, the opening time of the fuel injection valve in the compression stroke fuel injection at the time of engine start is determined according to the flowchart shown in FIG. This will be described together with the time chart of FIG. First, in step 101, it is determined whether or not the fuel pressure P in the pressure accumulating chamber 4 detected by the pressure sensor 4a is within a set range. The lower limit value P1 of the setting range is the fuel pressure that enables the above-described compression stroke injection, and is, for example, 3 MPa. In the compression stroke injection, if the fuel injection pressure is too high, the injected fuel tends to pass through the vicinity of the spark plug, and the tumble flow swirling vertically in the cavity formed in the piston top surface causes the air-fuel mixture in the vicinity of the spark plug. Even when used for formation, the injected fuel easily penetrates the tumble flow, and in any case, it becomes difficult to concentrate the injected fuel in the vicinity of the spark plug. Thereby, for example, 8 MPa is set as the upper limit value of the fuel pressure P in the pressure accumulation chamber 4.

  At the beginning of cranking, the fuel pressure in the pressure accumulating chamber 4 is near atmospheric pressure, and the determination in step 101 is denied. However, if the discharge of the high-pressure pump 5 is performed several times with the cranking, the pressure accumulating chamber The fuel pressure P within 4 exceeds the lower limit value P1 of the setting range, and the compression stroke injection becomes possible, and the determination in step 101 is affirmed. In the example shown in FIG. 2, the fuel pressure P in the pressure accumulating chamber 4 exceeds the lower limit value P1 of the set range due to the fuel discharge of the high pressure pump 5 at time t0. At this time, the compression stroke of the # 3 cylinder is in progress. As described above, it is preferable that the opening time of the fuel injection valve in the compression stroke fuel injection is determined during the intake stroke, whereby the fuel injection valve starts from the # 1 cylinder that reaches the intake stroke after time t0. 3 is determined, and the compression stroke fuel injection is started.

  When it is time t1 when the opening time T1 of the # 1 cylinder is determined, in step 102, the fuel injection time from the intake stroke of the # 1 cylinder, which determines the opening time T1 of the fuel injection valve 3, to the end of the compression stroke of the # 1 cylinder It is determined whether or not there is fuel discharge from the high-pressure pump 5. In the case of the # 1 cylinder, the fuel is discharged, that is, the fuel is pumped into the pressure accumulating chamber 4, so that the determination in step 102 is affirmed. In step 103, the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection. Is added to the measured fuel pressure P in the pressure accumulation chamber 4 by the fuel pressure increase in the pressure accumulation chamber 4 due to the previous fuel discharge (this time ΔP0 at time t0). Strictly speaking, the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection must be added to the fuel pressure P in the current pressure accumulating chamber 4 by the fuel pressure increase in the pressure accumulating chamber 4 due to future fuel discharge. Since this fuel pressure increase is an unknown value, the fuel pressure increase in the pressure accumulating chamber 4 due to the previous fuel discharge that is currently known is added. There is no significant difference between the fuel pressure increases associated with these two successive fuel discharges.

  Next, at step 105, it is determined whether or not there is fuel injection of other cylinders from the intake stroke of the # 1 cylinder that determines the valve opening time of the fuel injection valve 3 to the time of fuel injection at the end of the compression stroke of the # 1 cylinder. The In the case of the current # 1 cylinder fuel injection, there is no fuel injection in the other cylinders, so the determination in step 104 is negative and the routine proceeds to step 107. In step 107, the current valve opening time T1 of the fuel injection valve 3 of the # 1 cylinder is calculated based on the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection estimated in step 103 and the required fuel amount. As described above, the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection estimated for the calculation of the required fuel amount is also used. Thus, the calculation of the valve opening time T1 uses the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection rather than at the time of determination, so that a relatively accurate valve opening time T1 can be calculated. It is possible to reliably inject the required fuel amount at the time of injection.

  Next, at step 108, it is determined whether or not the current engine speed N has reached an idle speed N1, for example. When this determination is affirmative, the fuel pressure in the pressure accumulating chamber 4 is sufficiently high, and the calculated valve opening time is sufficiently short, so that the problem described below does not occur, and the engine Fuel injection is performed for the valve opening time calculated from the valve opening time set according to the rotational speed. However, when the determination at step 108 is negative, the routine proceeds to step 109.

  The initial valve opening timing of the fuel injection valve 3 is, for example, compression top dead center. If the fuel injection valve 3 is closed for the calculated valve opening time T1, the valve closing timing Ct (valve opening) is set. If the current engine speed, preferably the crank angle set based on the estimated engine speed at the time of fuel injection, is slower than the ignition timing At for the time T1, ignition is performed during fuel injection. There is a high probability of misfire. Accordingly, in this flowchart, in step 109, it is determined whether or not the ignition timing At is later than the valve closing timing Ct. In the example shown in FIG. 2, the ignition timing is indicated by an arrow, and in this fuel injection of the # 1 cylinder, this determination is denied. Therefore, the compression top dead center is set as the valve opening timing, and the set closing timing is set. Fuel injection is performed up to the valve timing. As a result, the required fuel amount is reliably injected, and combustion with a good ignition timing retard can be realized.

  This flowchart is repeated. When the opening time T2 of the # 4 cylinder is determined t2, in step 102, the opening stroke T2 of the fuel injection valve 3 is determined and the compression stroke of the # 4 cylinder is determined from the intake stroke of the # 4 cylinder. It is determined whether or not there is fuel discharge from the high-pressure pump 5 by the end of fuel injection. In the case of the current # 4 cylinder, fuel discharge has already been completed during the compression stroke of the # 1 cylinder, and this determination is denied. Therefore, in step 103, the fuel in the pressure accumulating chamber 4 at the time of fuel injection is determined. The pressure Pe is the fuel pressure P in the pressure accumulation chamber 4 at the current time (time t2). Next, in step 105, it is determined whether or not there is fuel injection in other cylinders from the intake stroke of the # 4 cylinder that determines the valve opening time T2 of the fuel injection valve 3 to the time of fuel injection at the end of the compression stroke of the # 4 cylinder. Is done. In the case of the current # 4 cylinder, there is fuel injection of the # 1 cylinder, so the determination in step 105 is affirmed and the routine proceeds to step 106.

  In step 106, the fuel pressure drop in the pressure accumulation chamber 4 accompanying the fuel injection of the # 1 cylinder from the fuel pressure Pe in the pressure accumulation chamber 4 at the time of fuel injection, which is the current fuel pressure P in the pressure accumulation chamber 4 in step 104 ( This time, ΔP2) is subtracted, and the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection is calculated. This fuel pressure drop ΔP2 is currently known because the opening time T1 of the fuel injection valve of the # 1 cylinder (that is, the fuel injection amount) is already known. It can be accurately calculated based on the fuel pressure in the pressure accumulating chamber 4.

  Next, at step 107, based on the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection estimated at step 106 and the required fuel amount, the valve opening time T2 of the current # 4 cylinder fuel injection valve 3 is calculated. . Thus, since the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection is used for calculating the valve opening time T2, rather than at the time of determination, the valve opening time T2 can be calculated relatively accurately. It is possible to reliably inject the required fuel amount at the time of injection. Next, when the current engine speed N is lower than the idle speed N1, the routine proceeds to step 109.

  The calculated valve opening time T2 of the # 4 cylinder is longer than the valve opening time T1 of the # 1 cylinder because the fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection is low, and the engine speed is also increased. Therefore, the closing timing Ct of the fuel injection valve 3 set based on the opening timing of the fuel injection valve 3 set to the compression top dead center becomes relatively late. As a result, in the example shown in FIG. 2, the current valve closing timing Ct is later than the ignition timing At, and misfires occur as it is. Therefore, if the determination in step 109 is negative, it is determined in step 109 whether or not the ignition timing At can be further retarded so that the valve closing timing Ct is earlier than the ignition timing At. .

  The compression stroke fuel injection and the significant ignition timing retardation are performed even during idling, and the ignition timing At is set so that output fluctuations do not increase between cylinders. However, the engine speed before reaching the idle speed N1 is currently increasing, and even if a relatively large output fluctuation occurs between the cylinders, the driver is not aware. Thereby, further retarding of the ignition timing is possible. However, the misfire limit cannot be exceeded. Based on these, when the determination in step 110 is affirmed, the ignition timing At is further retarded in step 111 to prevent the valve closing timing Ct from becoming later than the ignition timing At. On the other hand, if the delay of the further ignition timing exceeds the misfire limit, the determination in step 110 is denied, and in step 112, the valve opening timing of the fuel injection valve 3 is advanced and the valve closing timing Ct is ignited. It is prevented from becoming later than the timing At.

  When the valve opening timing of the fuel injection valve 3 is advanced, the piston position at the valve opening timing is lowered, so that the injected fuel easily adheres to the cylinder bore. Adhering fuel to the cylinder bore is not preferable because it dilutes engine oil and becomes fuel waste that does not contribute to combustion and deteriorates fuel consumption. Accordingly, when the valve closing timing Ct becomes later than the ignition timing At, it is desirable to retard the ignition timing rather than advance the valve opening timing.

  This flowchart is further repeated. When it is time t3 when the opening time T3 of the # 3 cylinder is determined, in step 102, the compression of the # 3 cylinder is determined from the intake stroke of the # 3 cylinder which determines the opening time T3 of the fuel injection valve 3. It is determined whether or not there is fuel discharge from the high-pressure pump 5 by the time of fuel injection at the end of the stroke. In the case of the current # 3 cylinder, since there is fuel discharge, the determination in step 102 is affirmed, and in step 103, the fuel pressure Pe in the pressure accumulation chamber 4 at the time of fuel injection is the current measured pressure accumulation chamber. 4 is added to the fuel pressure P in the fuel pressure increase in the pressure accumulation chamber 4 due to the previous fuel discharge (currently ΔP1).

  Next, at step 105, it is determined whether there is fuel injection from other cylinders from the intake stroke of the # 3 cylinder, which determines the valve opening time T3 of the fuel injection valve 3, to the time of fuel injection at the end of the compression stroke of the # 3 cylinder. Is done. In the case of the current # 3 cylinder, since there is fuel injection for # 4 cylinder, the routine proceeds to step 106. In step 106, the fuel pressure drop in the pressure accumulation chamber 4 accompanying the fuel injection of the # 4 cylinder (this time ΔP3) is subtracted from the fuel pressure Pe in the pressure accumulation chamber 4 at the time of fuel injection estimated in step 103, The fuel pressure Pe in the pressure accumulation chamber 4 at the time of injection is calculated. As for this fuel pressure drop ΔP3, the valve opening time T2 (that is, the fuel injection amount) of the # 4 cylinder fuel injection valve is currently known, and the pressure accumulation chamber 4 during fuel injection of the # 4 cylinder is known. Since the internal fuel pressure is estimated, it can be accurately calculated.

  Next, at step 107, based on the fuel pressure Pe in the pressure accumulating chamber 4 at the time of fuel injection estimated at step 106 and the required fuel amount, the valve opening time T3 of the current # 3 cylinder fuel injection valve 3 is calculated. . The calculated valve opening time T3 of the # 3 cylinder is shorter than the valve opening time T1 of the # 1 cylinder because the fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection is high. However, as the engine speed increases, the closing timing Ct of the fuel injection valve 3 tends to be delayed. Therefore, as the engine speed increases, the opening timing of the fuel injection valve 3 gradually increases from the compression top dead center. It is preferable to advance.

  Next, at the time t4 when the fuel injection valve opening time T4 of the # 2 cylinder is determined, the fuel pressure decrease ΔP5 accompanying the fuel injection of the # 3 cylinder is subtracted from the current fuel pressure P in the pressure accumulating chamber 4. The fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection is estimated. Next, at the time t5 when the fuel injection valve opening time T5 in the # 1 cylinder is determined, the fuel pressure decrease ΔP6 accompanying the fuel injection in the # 2 cylinder is subtracted from the current fuel pressure in the pressure accumulating chamber 4, and The fuel pressure increase ΔP4 accompanying the previous fuel discharge is added to estimate the fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection. Next, at the time t6 when the fuel injection valve opening time T6 of the # 4 cylinder is determined, the fuel pressure drop ΔP8 accompanying the fuel injection of the # 1 cylinder is subtracted from the current fuel pressure P in the pressure accumulating chamber 4. The fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection is estimated. Thus, the valve opening time in each cylinder is determined in advance relatively accurately by using the fuel pressure in the pressure accumulating chamber 4 at the time of fuel injection estimated, for example, during the intake stroke before the fuel injection timing at the end of the compression stroke. can do. As a result, if the closing timing of the fuel injection valve is later than the ignition timing, the ignition timing is retarded or the opening timing of the fuel injection valve is advanced so that the ignition is performed during fuel injection. It is possible to prevent a misfire from occurring.

  In step 109 of this flowchart, it is determined whether or not the ignition timing At is later than the closing timing Ct of the fuel injection valve. However, even if ignition is performed immediately after the end of fuel injection, the injected fuel is not vaporized. Since the combustion may become unstable due to sufficient, it may be determined whether or not the difference between the ignition timing At and the valve closing timing Ct is greater than or equal to a set value. That is, it is determined whether or not the ignition timing At is later than a set value by the valve closing timing Ct. When this judgment is denied, if the ignition timing is further retarded or the fuel injection valve opening timing is advanced, not only will misfiring occur, but combustion may become unstable. Can be prevented.

It is the schematic which shows the cylinder injection type spark ignition internal combustion engine to which the control apparatus by this invention is attached. 3 is a time chart showing a change in fuel pressure in a pressure accumulating chamber in the initial stage of engine startup. It is a flowchart for determining the valve opening time of the fuel injection valve implemented by the control apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 2 Spark plug 3 Fuel injection valve 4 Accumulation chamber 5 High pressure pump

Claims (5)

  In the control device for a cylinder injection type spark ignition internal combustion engine, the opening time of the fuel injection valve of each cylinder at the time of compression stroke fuel injection at the time of engine start is determined based on the required fuel amount and the fuel pressure in the pressure accumulating chamber. Estimating the fuel pressure in the pressure accumulating chamber at the time of fuel injection based on the fuel pressure in the pressure accumulating chamber at the time of determining the valve time, and determining the valve opening time by using the estimated fuel pressure in the pressure accumulating chamber at the time of fuel injection An in-cylinder injection spark ignition internal combustion engine control device.   When there is fuel pumping to the pressure accumulating chamber from the time of determining the valve opening time to the time of fuel injection, the fuel pressure increase in the pressure accumulating chamber due to the previous fuel pumping is added to the fuel pressure at the time of determining the valve opening time, 2. The control apparatus for a direct injection spark ignition internal combustion engine according to claim 1, wherein the fuel pressure in the pressure accumulating chamber at the time of fuel injection is estimated at the time of determining the valve opening time.   When there is fuel injection to another cylinder from the time of determining the valve opening time to the time of fuel injection, the fuel pressure drop in the pressure accumulating chamber due to the fuel injection to the other cylinder is determined from the fuel pressure at the time of determining the valve opening time. 3. The control device for a cylinder injection type spark ignition internal combustion engine according to claim 2, wherein the control is performed by subtracting and estimating the fuel pressure in the pressure accumulating chamber at the time of fuel injection when the valve opening time is determined.   When the closing timing of the fuel injection valve based on the determined opening time is later than the ignition timing, the ignition timing is retarded so that the closing timing of the fuel injection valve is earlier than the ignition timing. Item 4. The control device for the cylinder injection spark ignition internal combustion engine according to any one of Items 1 to 3.   When the closing timing of the fuel injection valve based on the determined opening time is later than the ignition timing, the opening timing of the fuel injection valve is advanced to make the closing timing of the fuel injection valve earlier than the ignition timing. The control device for an in-cylinder injection spark ignition internal combustion engine according to any one of claims 1 to 3.

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