JP4597220B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a direct injection internal combustion engine, and more particularly, to a control device for an internal combustion engine that performs accurate fuel amount control upon normal recovery from a fuel system abnormality.

  As a conventional technology of an internal combustion engine in which a fuel injection valve is disposed in a combustion chamber and fuel is directly injected into the combustion chamber, that is, a so-called in-cylinder injection internal combustion engine, there is the following. This conventional device detects the actual fuel pressure acting on the fuel injection valve, controls it to match the target fuel pressure, and corrects the drive time of the fuel injection valve by the ratio between the detected fuel pressure and the reference fuel pressure. (For example, refer to Patent Document 1).

  In the invention of Patent Document 1, under the same basic fuel injection pulse width, the fuel injection amount increases as the fuel pressure increases. That is, the fuel pressure correction of the drive time of the fuel injection valve is performed based on the relationship that the fuel injection amount is approximately proportional to the 1/2 power of the fuel pressure. Therefore, in order to obtain the same fuel injection amount as that at the reference fuel pressure even if the fuel pressure changes, the decrease correction is performed on the basic drive time of the fuel injection valve as the fuel pressure Pf increases with respect to the reference fuel pressure. On the other hand, an increase correction is performed on the basic drive time of the fuel injection valve as the fuel pressure Pf decreases with respect to the reference fuel pressure. That is, the fuel pressure correction coefficient is set on the basis of the 1/2 power of (reference fuel pressure / fuel pressure Pf).

  In addition, there is a conventional fuel system of an internal combustion engine that performs feedback control of fuel pressure while variably controlling the fuel discharge amount of the fuel pump (see, for example, Patent Document 2). In the invention of this Patent Document 2, when a fuel system abnormality such as a component failure or a fuel pressure feedback system control failure occurs, the fuel pressure feedback control is stopped and the fuel control is performed with the feed pressure. At this time, when the fuel injection amount is larger than the permissible maximum injection amount, a fail-safe control technique for implementing fuel cut or intake air amount restriction has been proposed.

  In addition, as a means for improving the accuracy of fuel injection in the transition period of fuel pressure change, there is a conventional technique related to a fuel pressure value estimation method (see, for example, Patent Document 3). In order to reduce the influence of noise etc. from the detection value (hereinafter referred to as “fuel pressure sensor value”) that is actually output from the fuel pressure sensor, the variable fuel pressure system performs an average calculation to suppress the average fluctuation pressure ( Actual fuel pressure) is used for fuel pressure control and fuel control.

  This actual fuel pressure is output with a response delay from the fuel pressure sensor value. Accordingly, when the output of the actual fuel pressure sensor changes abruptly, the fuel pressure sensor value is output later than that, making accurate fuel injection difficult. For this reason, the invention of Patent Document 3 estimates the change in fuel pressure in a region where the difference between the fuel pressure sensor value and the actual fuel pressure becomes large when the fuel pressure changes transiently.

JP-A-10-26046 JP 2000-130232 A JP 2001-336436 A

However, the prior art has the following problems.
In the preceding example described in Patent Document 2 described above, when the normal state is recovered from the abnormality occurrence state, the fuel pressure feedback control of the high pressure pump is resumed. However, the differential pressure between the target fuel pressure value at normal time set from the operating state and the feed pressure that is the actual fuel pressure at the time of fail-safe control is large. For this reason, the fuel discharge flow rate of the high-pressure pump at the time of normal recovery increases, and the fuel pressure rises rapidly. As a result, the difference between the actual effective fuel pressure and the actual fuel pressure (average fuel pressure) used for control increases.

  Thus, when the fuel pressure changes transiently, the prior art according to Patent Document 3 described above performs correction of the fuel injection valve drive time using the estimated fuel pressure when determining the fuel pressure change transition period. ing. Here, the estimated fuel pressure is stored as a map of the fuel injection amount and the engine speed, or the fuel pressure change speed corresponding to the fuel pressure and the engine speed, and the fuel pressure change speed obtained by map search based on the operating state, Estimated based on the previous actual fuel pressure (average fuel pressure).

  However, in such an estimation method, the fuel temperature is not considered in the calculation of the fuel pressure change rate. For this reason, if the volume expansion coefficient changes due to a change in fuel temperature, an accurate fuel pressure change rate cannot be obtained, and an error occurs between the estimated fuel pressure and the effective fuel pressure.

  Also proposed is a method for estimating the fuel pressure change rate obtained from the difference between the previous actual fuel pressure (average fuel pressure) and the previous actual fuel pressure (average fuel pressure) in the fuel injection cycle, and the previous actual fuel pressure (average fuel pressure). Has been. However, the effective fuel pressure changes according to the amount of fuel change in the pressure accumulator chamber (difference between the fuel discharge amount of the high pressure pump and the fuel injection amount of the fuel injection valve). Since the amount and the fuel injection amount of the fuel injection valve both change, an accurate fuel pressure change speed cannot be obtained by this method, and an error occurs between the estimated fuel pressure and the effective fuel pressure.

  Further, as shown in the prior art related to Patent Document 1, the fuel injection valve drive time is corrected based on the fuel pressure correction coefficient based on the relationship that the fuel injection amount is approximately proportional to the 1/2 power of the fuel pressure (reference value). (Fuel pressure / actual fuel pressure) is set to be 1/2 power. Therefore, the lower the fuel pressure, the greater the effect of the error between the estimated fuel pressure and the effective fuel pressure on the correction of the fuel injection valve drive time.

  Therefore, even if the fuel pressure estimation is performed at the time of fuel pressure increase transition at the time of normal recovery from the state where the feed pressure is in the fail-safe control at the time of the fuel system abnormality, particularly at low fuel pressure, the fuel pressure estimation as described above is still performed. The fuel pressure correction corresponding to the effective fuel pressure at the injection timing cannot be performed. In addition, when the fuel pressure rises transiently, fuel injection cannot be completed during the injectable period in the cycle, and misfire due to leaning may occur.

  The present invention has been made in order to solve the above-described problems, and performs accurate fuel amount control at the time of a transient increase in fuel pressure at the time of normal recovery from the time when the fuel system is abnormal, and the air-fuel ratio is lower than an appropriate value. An object of the present invention is to provide a control device for an internal combustion engine that can prevent a misfire due to a rich or lean state.

A control apparatus for an internal combustion engine according to the present invention includes a high-pressure fuel pump that sucks fuel and discharges pressurized fuel, and a fuel injection valve that directly injects fuel discharged from the high-pressure fuel pump into a cylinder of the internal combustion engine. A fuel pressure detecting means for detecting the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump, a fuel pressure averaging means for calculating the actual fuel pressure by averaging the fuel pressure detected by the fuel pressure detecting means, and an abnormality in the fuel system A fuel system abnormality judging means for judging, a basic target fuel pressure setting means for setting a basic target fuel pressure according to the operating state of the internal combustion engine, and a state in which the fuel system abnormality judging means diagnoses that there is an abnormality in the fuel system. It is set by the target fuel pressure setting means for normal recovery that sets the target fuel pressure for normal recovery that gradually increases from a predetermined value lower than the basic target fuel pressure at the time of normal recovery, and by the target fuel pressure setting means for normal recovery at the time of normal recovery A target fuel pressure switching means for selecting the target fuel pressure at the time of normal return as the target fuel pressure, and then selecting the basic target fuel pressure set by the basic target fuel pressure setting means as the target fuel pressure when a predetermined switching condition is satisfied; Fuel pressure control means for controlling the amount of fuel discharged from the high-pressure fuel pump so that the fuel pressure matches the target fuel pressure, and a low-pressure that pumps up the fuel in the fuel tank and supplies the fuel adjusted to the feed pressure to the high-pressure fuel pump A normal return target fuel pressure setting means includes a fuel pump, and sets the feed pressure as a predetermined value lower than the basic target fuel pressure at the time of normal return .

  According to the present invention, the target fuel pressure is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the fuel system abnormal state. Therefore, when the target fuel pressure at the time of normal recovery is set to the basic target fuel pressure In comparison, the discharge amount of the high-pressure pump at the time of fuel pressure rise transient can be suppressed, the fuel amount control is performed accurately at the time of fuel pressure rise transient at the time of normal recovery from the fuel system abnormality, and the air-fuel ratio is richer than the appropriate value, or A control device for an internal combustion engine that can prevent a misfire due to a lean state can be obtained.

  A preferred embodiment of a control apparatus for an internal combustion engine of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram schematically showing a control device for an internal combustion engine according to Embodiment 1 of the present invention. The control apparatus for an internal combustion engine shown in FIG. 1 includes a normally open flow control valve 10 having a solenoid 11 as a fuel supply system, a cylinder 21, a plunger 22, a pressurizing chamber 23, and a fuel discharge valve (check valve). ) 34, the camshaft 24 of the internal combustion engine 40 having the pump cam 25, the fuel tank 30 filled with fuel, and the low pressure fuel pump 31 and the low pressure regulator 32 to be connected to the fuel tank 30. The low pressure passage 33, the high pressure passage (discharge passage) 35 connected to the pressure accumulating chamber 36 via the fuel discharge valve 34, and the relief passage connecting the pressure accumulating chamber 36 and the fuel tank 30 via the relief valve 37. 38 and a fuel injection valve 39 for supplying the fuel accumulated in the pressure accumulating chamber 36 to each combustion chamber of the internal combustion engine 40.

  Further, as a control system, an ECU 60 that energizes the solenoid 11 to control the closing timing of the flow control valve 10 is provided. Detection signals from various sensors such as a fuel pressure sensor 61, a rotation sensor 62, an accelerator position sensor 63, and an intake manifold pressure sensor 64 are input to the ECU 60 as operation information of the internal combustion engine 40.

  The low pressure fuel pump 31 pumps up the fuel in the fuel tank 30 and discharges it to the low pressure passage 33. The high pressure fuel pump 20 sucks and discharges the fuel discharged from the low pressure fuel pump 31 into the pressurizing chamber 23. The low pressure passage 33 is connected to the upstream side of the pressurizing chamber 23 in the high pressure fuel pump 20 via the flow rate control valve 10. That is, the flow control valve 10 is disposed in a fuel passage that connects the low pressure passage 33 and the pressurizing chamber 23. The fuel discharge valve 34 is disposed in a high-pressure passage 35 that connects the pressurizing chamber 23 and the pressure accumulating chamber 36.

  The fuel injection valve 39 directly injects and supplies the high-pressure fuel in the pressure accumulating chamber 36 into each combustion chamber for each cylinder of the internal combustion engine 40. The fuel pressure sensor 61 detects the fuel pressure in the pressure accumulation chamber 36 and outputs it to the ECU 60.

  On the low pressure passage 33 side of the fuel supply system, the fuel discharged from the low pressure fuel pump 31 is adjusted to a predetermined feed pressure (for example, 0.4 MPa) by the low pressure regulator 32, and the plunger 22 is lowered in the cylinder 21. It is introduced into the pressurizing chamber 23 through the flow rate control valve 10 which is opened when moving.

  The plunger 22 reciprocates in the cylinder 21 in synchronization with the rotation of the internal combustion engine 40. Accordingly, the high pressure fuel pump 20 sucks fuel into the pressurizing chamber 23 through the flow rate control valve 10 opened from the low pressure passage 33 during the downward movement period of the plunger 22 (fuel suction stroke). . On the other hand, during the upward movement of the plunger 22 (fuel discharge stroke), the fuel in the pressurizing chamber 23 is pressurized to a high pressure while the flow rate control valve 10 is closed, and the fuel is supplied to the pressure accumulating chamber 36 through the fuel discharge valve 34. Supply by pressure.

  The pressurizing chamber 23 is defined by the inner peripheral wall surface of the cylinder 21 and the upper end surface of the plunger 22. The lower end of the plunger 22 is in pressure contact with a pump cam 25 provided on the cam shaft 24 of the internal combustion engine 40. Then, the pump cam 25 rotates in conjunction with the rotation of the cam shaft 24, whereby the plunger 22 reciprocates in the cylinder 21 so that the volume in the pressurizing chamber 23 is expanded / reduced.

  The high-pressure passage 35 connected to the downstream side of the pressurizing chamber 23 is connected to a pressure accumulating chamber via a normally closed fuel discharge valve 34 that is a check valve that allows only fuel flow from the pressurizing chamber 23 toward the pressure accumulating chamber 36. 36. The pressure accumulating chamber 36 accumulates and holds the high-pressure fuel discharged from the pressurizing chamber 23 and distributes the accumulated high-pressure fuel to the fuel injection valves 39.

  The relief valve 37 connected to the pressure accumulating chamber 36 is a normally closed valve that opens at a predetermined pressure (opening pressure set value) or higher, and the fuel pressure in the pressure accumulating chamber 36 is higher than the valve opening pressure set value of the relief valve 37. When it tries to rise, it opens. As a result, the fuel in the pressure accumulating chamber 36 that is about to rise above the valve opening pressure set value is returned to the fuel tank 30 through the relief passage 38 so that the fuel pressure in the pressure accumulating chamber 36 is prevented from becoming excessive. It has become.

  The flow rate control valve 10 provided in the low-pressure passage 33 connecting the low-pressure fuel pump 31 and the pressurizing chamber 23 is controlled in valve closing drive timing under the control of the ECU 60 (that is, the energization timing of the solenoid 11 is controlled). The fuel discharge amount from the high-pressure fuel pump 20 to the pressure accumulating chamber 36 is adjusted. In the high-pressure fuel pump 20, when the plunger 22 moves upward in the cylinder 21, the pressure control chamber 23 is moved in accordance with the upward movement of the plunger 22 while the flow rate control valve 10 is open (the solenoid 11 is energized off). The sucked fuel is returned from the pressurizing chamber 23 to the low pressure passage 33 through the flow control valve 10. Therefore, the high pressure fuel is not pumped into the pressure accumulating chamber 36.

  On the other hand, after the flow rate control valve 10 is closed (the solenoid 11 is energized) at a predetermined timing when the plunger 22 is moving upward in the cylinder 21, the pressure is increased in the pressurizing chamber 23 according to the upward movement of the plunger 22. The fuel thus discharged is discharged to the fuel discharge valve 34 and is pumped to the pressure accumulating chamber 36 through the high pressure passage 35.

  The ECU 60 detects the fuel pressure in the pressure accumulating chamber 36 detected by the fuel pressure sensor 61, the rotational position and rotational speed of the internal combustion engine 40 detected by the output signal pulse of the rotation sensor 62, and the depression of the accelerator pedal detected by the accelerator position sensor 63. The amount, intake manifold pressure detected by the intake manifold pressure sensor 64, and the like are captured as various operation state information.

  The ECU 60 determines a target pressure based on the rotational speed of the internal combustion engine 40 detected by the output signal pulse of the rotation sensor 62 and the accelerator pedal depression amount detected by the accelerator position sensor 63. Further, the ECU 60 controls the valve closing drive timing of the flow rate control valve 10 (the energization timing of the solenoid 11) so that the target pressure and the fuel pressure in the pressure accumulating chamber 36 detected by the fuel pressure sensor 61 coincide with each other. The amount of fuel discharged from the fuel pump 20 to the pressure accumulating chamber 36 is controlled.

  In addition to the fuel pressure in the pressure accumulating chamber 36 detected by the fuel pressure sensor 61, the rotational speed NE and the rotational position RP of the internal combustion engine 40 detected by the rotation sensor 62, and the intake manifold pressure PB detected by the intake manifold pressure sensor, the ECU 60 The valve opening period and drive timing of the fuel injection valve 39 are controlled based on operation information from various sensors that do not. Accordingly, an appropriate fuel injection amount is injected and supplied into the cylinder of the internal combustion engine 40 at an appropriate timing according to the operating state.

  Next, a specific configuration of the ECU 60 will be described. FIG. 2 is a functional block diagram of ECU 60 in the first embodiment of the present invention. The ECU 60 in FIG. 2 includes basic target fuel pressure setting means (basic target fuel pressure map) 601, fuel pressure averaging means 602, fuel system abnormality determination means 603, differential pressure calculation means 604, normal return target fuel pressure setting means 605, target fuel pressure switching. Means 606, fuel pressure control means 607, fuel injection valve drive time correction means 608, fuel injection valve control means 609, and fuel amount restriction determination means 610 are provided.

  The ECU 60 receives, as inputs, a fuel pressure sensor 61 that detects the fuel pressure PF in the accumulator 36, a rotation sensor 62 that detects the rotational position or rotational speed NE of the internal combustion engine 40, and an accelerator position that detects the accelerator pedal depression amount AP. Various sensors including a sensor 63 and an intake manifold pressure sensor 64 for detecting the intake manifold pressure are connected.

  Further, the ECU 60 is connected with various actuators including an output control valve 10 for controlling the fuel discharge amount of the high-pressure fuel pump 20 and a fuel injection valve 39 for directly injecting fuel into the cylinder of the internal combustion engine 40 as outputs. Has been.

  The basic target fuel pressure setting means 601 determines the basic target fuel pressure POb based on the rotational speed NE detected by the rotation sensor 62 and the accelerator pedal depression amount AP detected by the accelerator position sensor 63. The fuel pressure averaging means 602 averages the fuel pressure detected by the fuel pressure sensor 61 in synchronization with a predetermined crank angle, and calculates the actual fuel pressure PF.

  The fuel system abnormality determination means 603 determines the presence or absence of a fuel system abnormality such as a component failure or fuel pressure feedback system control failure. The differential pressure calculation means 604 calculates a differential pressure ΔP1 between the basic target fuel pressure calculated by the basic target fuel pressure setting means 601 and the actual fuel pressure PF calculated by the fuel pressure averaging means 602.

  The normal return target fuel pressure setting unit 605 sets a predetermined value POrs lower than the basic target fuel pressure POb to a normal return target fuel pressure when the fuel system abnormality determination unit 603 switches from the state in which the fuel system abnormality determination unit 603 determines abnormality of the fuel system to normal determination. Set to POr. Thereafter, the normal return target fuel pressure setting means 605 calculates the gradual amplification of the normal return target fuel pressure POr on the basis of the differential pressure ΔP1 calculated by the differential pressure calculation means 604 and the basic target fuel pressure POb at predetermined intervals, and normal The target fuel pressure POr at the time of return is gradually increased.

  The normal return target fuel pressure setting means 605 sets the gradual amplification of the normal return target fuel pressure POr smaller as the differential pressure ΔP1 is larger. Further, since the influence of the fuel pressure deviation becomes larger as the fuel pressure becomes lower, the target fuel pressure setting means 605 at normal return gradually amplifies the target fuel pressure POr at normal return as the basic target fuel pressure POb is lower even if the differential pressure ΔP1 is the same. Set to a smaller value.

  The target fuel pressure switching means 606 switches the target fuel pressure PO to the target fuel pressure POr at the time of normal return when the fuel system abnormality determination means 603 switches from the state in which the fuel system abnormality determination means 603 has determined abnormality to normality.

  The fuel pressure control means 607 performs a proportional integral feedback calculation based on the fuel pressure deviation ΔP between the target fuel pressure PO and the actual fuel pressure PF to calculate the target fuel discharge amount QO. Then, the fuel pressure control means 607 determines the valve closing timing TP of the flow rate control valve 10 based on the target discharge amount QO and the rotational speed NE detected by the rotation sensor 62.

  Further, the fuel pressure control means 607 is a solenoid that controls the flow rate control valve 10 to close at the valve closing timing TP of the flow rate control valve 10 based on the rotational position RP of the internal combustion engine 40 detected by the rotation sensor 62. 11 energization timing is controlled. As a result, the amount of fuel necessary for the target pressure PO and the actual fuel pressure PF in the pressure accumulation chamber 36 to coincide with each other is discharged from the high-pressure fuel pump 20 to the pressure accumulation chamber 36.

  Further, when the fuel system abnormality determination unit 603 determines that the fuel pressure system is abnormal, the fuel pressure control unit 607 stops the feedback calculation of the fuel pressure and performs fail-safe control for stopping the high-pressure pump. In this case, the actual fuel pressure PF during the execution of the fail safe control becomes the feed pressure.

  The fuel injection valve drive time correction unit 608 calculates a fuel pressure correction coefficient KPF (= (reference fuel pressure / actual fuel pressure PF) to the power of ½) based on the actual fuel pressure PF calculated by the fuel pressure averaging unit 602.

  The fuel injection valve control means 609 is based on operating information from various sensors (not shown) in addition to the rotational speed NE and rotational position RP of the internal combustion engine 40 detected by the rotation sensor 62 and the intake manifold pressure PB detected by the intake manifold pressure sensor. The fuel injection amount QF and the fuel injection timing are determined. Further, the fuel injection valve control means 609 calculates the drive time (valve opening period) PW (= QF × fuel pressure correction coefficient KPF × drive time conversion coefficient + dead time TD) of the fuel injection valve 39. Control valve opening period and drive timing. Thus, an appropriate fuel injection amount is injected and supplied into the cylinder of the internal combustion engine 40 at an appropriate timing according to the operating state.

  Based on the determination result of the fuel system abnormality determination unit 603, the determination result of the target fuel pressure switching unit 606, and the rotational speed NE detected by the rotation sensor 62, the fuel amount restriction determination unit 610 determines that the fuel injection valve drive period is a period cycle. It is determined whether or not a fuel amount restriction is necessary to prevent lean combustion due to exceeding the possible injection period. Further, when it is determined that the fuel amount restriction is necessary, the fuel amount restriction determination unit 610 sets a fuel cut request flag, and thereby the fuel injection valve control unit 609 performs the fuel cut.

  Next, the operation of the target fuel pressure switching means 606 of the present invention will be described. FIG. 3 is a flowchart showing a series of operations of the target fuel pressure switching means 606 in the first embodiment of the present invention.

  First, in step S301, based on the determination result of the fuel system abnormality determination means 603, it is determined whether or not “immediately after shifting from the fuel system abnormality to the normal state”. If it is determined in step S301 that the fuel system abnormality has just shifted to the normal state, the process proceeds to step S302, the target fuel pressure switching flag F1 is set to F1 = 1 (true), and the process proceeds to step S303.

  On the other hand, if it is determined in step S301 that it is not immediately after the fuel system abnormality has shifted to the normal state, the process immediately proceeds to step S303.

  In the next step S303, it is determined whether or not the target fuel pressure switching flag F1 is F1 = 1 (true). If YES in step S303, the process proceeds to step S304. If NO, the process proceeds to step S307.

  In step S303, when it is determined that the target fuel pressure switching flag F1 is F1 = 1 (true) and the process proceeds to step S304, it is determined whether or not the normal return target fuel pressure POr is equal to or higher than the basic target fuel pressure POb. Is done.

  Then, in the previous step S303, it is determined that the target fuel pressure switching flag F1 is F1 = 1 (true), and in the previous step S304, it is determined that the normal return target fuel pressure POr is not equal to or higher than the basic target fuel pressure POb. In this case, the process proceeds to step S305, where the target fuel pressure PO is set to the normal return target fuel pressure POr.

  On the other hand, if it is determined in step S304 that the target fuel pressure POr at normal return is greater than or equal to the basic target fuel pressure POb, the process proceeds to step S306, and the target fuel pressure switching flag F1 is set to F1 = 0 (false). Thereafter, the process proceeds to step S307, and the target fuel pressure PO is set to the basic target fuel pressure POb.

  Further, when it is determined in step S303 that the target fuel pressure switching flag F1 is not F1 = 1 (true) and the process proceeds to step S307, the target fuel pressure PO is set as the basic target fuel pressure POb.

  Thereafter, fuel pressure control is performed by the fuel pressure control means 607 in accordance with the target fuel pressure PO determined in step S305 or step S307.

  Next, the operation of the fuel amount restriction determination unit 610 will be described. FIG. 4 is a flowchart showing a series of operations of the fuel amount restriction determination means 610 according to Embodiment 1 of the present invention.

  First, in step S401, it is determined whether or not fuel system abnormality determination is established. If YES in step S401, the process proceeds to step S402, the fuel amount restriction determination execution flag F2 = 1 (true) is set, and the process proceeds to step S405.

  On the other hand, if the determination in step S401 is NO, the process proceeds to step S403, where it is determined whether or not “target fuel pressure switching flag F1 = 0 (false)”. If NO in step S403, the process proceeds to step S405. If YES, the fuel amount restriction determination execution flag F2 is set to 0 (false), and the process proceeds to step S405.

  In the next step S405, it is determined “whether or not the fuel amount restriction determination execution flag F2 = 1 (true)”. If YES in step S405, the process proceeds to step S406. Then, in step S406, “whether or not the rotational speed NE is equal to or higher than a predetermined value” is determined.

  Further, if the rotational speed NE is greater than or equal to the predetermined value in the determination in step S406, the process proceeds to step S407, and a fuel cut request flag is set. Here, the predetermined value in step S406 includes, for example, a rotational speed at which the air-fuel ratio becomes leaner by 25% or more than the target air-fuel ratio when the drive period of the fuel injection valve exceeds the injectable period in the engine cycle. Is set.

  On the other hand, if the fuel amount limitation determination execution flag F2 = 1 (true) is not determined in the previous step S405, and the fuel amount limitation determination execution flag F2 = 1 (true) in the previous step S405, and the previous step S406 is determined. If the rotational speed NE is not equal to or higher than the predetermined value, the routine is directly exited.

  As described above, according to the first embodiment, there is a configuration in which the target fuel pressure is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the fuel system abnormal state. Furthermore, the target fuel pressure at normal recovery is compared with the target fuel pressure at normal recovery, and until the condition that the target fuel pressure at normal recovery is equal to or higher than the basic target fuel pressure is satisfied, the target fuel pressure at normal recovery is the target fuel pressure. Fuel pressure switching means is provided.

  For this reason, compared with the case where the target fuel pressure at the time of normal return is made the basic target fuel pressure, the discharge amount of the high-pressure pump at the time when the fuel pressure rises can be suppressed. Therefore, the change in fuel pressure in the actual fuel pressure (average fuel pressure) calculation section used for fuel injection valve drive time correction is suppressed, and the deviation between the effective fuel pressure of the fuel injector injection timing and the actual fuel pressure (average fuel pressure) during the transient increase in fuel pressure is suppressed. it can. As a result, accurate fuel injection is possible even during a transient increase in fuel pressure.

  Furthermore, by setting the feed pressure, which is the actual fuel pressure at the time of normal recovery, as the initial value of the target fuel pressure at the time of normal recovery, the fuel injection valve is generated by increasing the discharge amount of the high-pressure pump immediately after normal recovery and the fuel pressure rapidly rising A deviation between the effective fuel pressure at the injection timing and the actual fuel pressure (average fuel pressure) can be reliably suppressed. As a result, accurate fuel injection can be performed from the failure recovery timing.

  Further, after the abnormality is determined by the fuel system abnormality determining means, the fuel amount restriction determining means for restricting the injection amount by the fuel cut when it is determined that the fuel injection amount is insufficient is provided. After the normal return determination is made by the system abnormality determination means, the determination of the fuel injection shortage region is continued until the target fuel pressure switching means switches the target fuel pressure from the target fuel pressure at normal return to the basic target fuel pressure.

  As a result, during a fuel pressure increase transition after the normal return determination by the fuel system abnormality determination means, due to the suppression of the fuel pressure increase rate, the fuel injection cannot be completed in the injectable period in the cycle and the lean misfire due to fuel shortage Can be prevented.

Embodiment 2. FIG.
In the first embodiment, the target fuel pressure switching means is provided, and the target fuel pressure PO is maintained until the target fuel pressure POr at the time of normal recovery becomes equal to or higher than the basic target fuel pressure POb determined according to the operation state at the time of normal recovery from the fuel system abnormality. In the above description, the target fuel pressure POr at the time of normal recovery is described. On the other hand, in the second embodiment of the present invention, a case where the target fuel pressure PO is switched based on the actual fuel pressure will be described.

  The configuration of the control device for the internal combustion engine in the second embodiment is the same as that in FIGS. 1 and 2 used in the first embodiment. However, the second embodiment is different from the first embodiment in the target fuel pressure switching condition of the target fuel pressure switching means 606. FIG. 5 is a flowchart showing a series of operations of the target fuel pressure switching means 606 in the second embodiment of the present invention.

  First, in step S501, based on the determination result of the fuel system abnormality determination means 603, it is determined whether or not “immediately after shifting from the fuel system abnormality to the normal state”. If it is determined in step S501 that the fuel system abnormality has just shifted to the normal state, the process proceeds to step S502, the target fuel pressure switching flag F1 is set to F1 = 1 (true), and the process proceeds to step S503.

  On the other hand, if it is determined in step S501 that it is not immediately after the fuel system abnormality has shifted to the normal state, the process immediately proceeds to step S503.

  In the next step S503, “whether or not the target fuel pressure switching flag F1 is F1 = 1 (true)” is determined. If YES in step S503, the process proceeds to step S504. If NO, the process proceeds to step S507.

  If it is determined in step S503 that the target fuel pressure switching flag F1 is F1 = 1 (true) and the process proceeds to step S504, it is determined whether or not the actual fuel pressure PF is equal to or greater than a predetermined value.

  Here, the predetermined value in step S503 is, for example, a fuel pressure correction coefficient KPF (= () calculated based on the actual fuel pressure PF when the difference between the actual fuel pressure PF and the effective fuel pressure at the fuel injection timing is 0.5 MPa. The fuel pressure value at which the error between the standard fuel pressure / fuel pressure PF) and the fuel pressure correction coefficient calculated based on the effective fuel pressure (= (standard fuel pressure / effective fuel pressure) 1/2 power) is less than 10%. Is set as

  If it is determined in step S503 that the target fuel pressure switching flag F1 is F1 = 1 (true) and it is determined in step S504 that the actual fuel pressure PF is not equal to or greater than the predetermined value, step S503 is performed. Proceeding to S505, the target fuel pressure PO is set to the normal return target fuel pressure POr.

  On the other hand, if it is determined in step S504 that the actual fuel pressure PF is equal to or greater than the predetermined value, the process proceeds to step S506, where the target fuel pressure switching flag F1 is set to F1 = 0 (false), and then, in step S507. Going forward, the target fuel pressure PO is set to the basic target fuel pressure POb.

  Even when it is determined in step S503 that the target fuel pressure switching flag F1 is not F1 = 1 (true) and the process proceeds to step S507, the target fuel pressure PO is set to the basic target fuel pressure POb.

  Thereafter, fuel pressure control is performed by the fuel pressure control means 607 in accordance with the target fuel pressure PO determined in step S505 or step S507.

  As described above, according to the second embodiment, the actual fuel pressure is compared with the predetermined value, and the target fuel pressure at the time of normal recovery is set as the target fuel pressure until the condition that the actual fuel pressure becomes equal to or higher than the predetermined value is satisfied. Fuel pressure switching means is provided. For this reason, in addition to the effect of previous Embodiment 1, it has the following effects.

  In the region where the effect of the difference between the effective fuel pressure of the fuel injection valve injection timing and the actual fuel pressure (average fuel pressure) becomes a problem, the target fuel pressure is gradually increased by gradually increasing the target fuel pressure at normal recovery. In the area where fuel injection accuracy deterioration due to fuel pressure deviation can be reliably prevented and the influence of deviation between the effective fuel pressure of fuel injection valve injection timing and the actual fuel pressure (average fuel pressure) is small, the basic target that determines the target fuel pressure according to the operating state The fuel pressure can be gradually increased to the fuel pressure.

Embodiment 3 FIG.
In the first embodiment, the target fuel pressure is switched based on the fuel pressure at normal return, and in the previous embodiment 2, the case where the target fuel pressure is switched based on the actual fuel pressure has been described. On the other hand, in the third embodiment, a case will be described in which the target fuel pressure is switched based on both the normal return fuel pressure and the actual fuel pressure.

  The configuration of the control device for the internal combustion engine in the third embodiment is the same as that in FIGS. 1 and 2 used in the first and second embodiments. However, the third embodiment is different from the first and second embodiments in the target fuel pressure switching condition of the target fuel pressure switching means 606. FIG. 6 is a flowchart showing a series of operations of target fuel pressure switching means 606 in the third embodiment of the present invention.

  First, in step S601, based on the determination result of the fuel system abnormality determination means 603, it is determined whether or not “immediately after shifting from the fuel system abnormality to the normal state”. If it is determined in step S601 that the fuel system abnormality has just shifted to the normal state, the process proceeds to step S602, the target fuel pressure switching flag F1 is set to F1 = 1 (true), and the process proceeds to step S603.

  On the other hand, if it is determined in step S601 that it is not immediately after the fuel system abnormality has shifted to the normal state, the process immediately proceeds to step S603.

  In the next step S603, “whether or not the target fuel pressure switching flag F1 is F1 = 1 (true)” is determined. If YES in step S603, the process proceeds to step S604. If NO, the process proceeds to step S608.

  In step S603, when it is determined that the target fuel pressure switching flag F1 is F1 = 1 (true) and the process proceeds to step S604, it is determined whether or not the normal return target fuel pressure POr is equal to or higher than the basic target fuel pressure POb. Is done. Further, if NO is determined in step S604, the process proceeds to step S605, where it is determined whether or not the actual fuel pressure PF is equal to or greater than a predetermined value.

  In step S603, it is determined that the target fuel pressure switching flag F1 is F1 = 1 (true), and in step S604, it is determined that the normal return target fuel pressure POr is not equal to or higher than the basic target fuel pressure POb. If it is determined in step S605 that the actual fuel pressure PF is not equal to or higher than the predetermined value, the process proceeds to step S606, where the target fuel pressure PO is set to the normal return target fuel pressure POr.

  On the other hand, if it is determined in step S604 that the normal return target fuel pressure POr is greater than or equal to the basic target fuel pressure POb, or if it is determined in step S605 that the actual fuel pressure PF is greater than or equal to a predetermined value, step S604 is performed. Proceeding to S607, the target fuel pressure switching flag F1 is set to F1 = 0 (false), and then proceeding to Step S608 to set the target fuel pressure PO as the basic target fuel pressure POb.

  Even when it is determined in step S603 that the target fuel pressure switching flag F1 is not F1 = 1 (true) and the process proceeds to step S608, the target fuel pressure PO is set as the basic target fuel pressure POb.

  Thereafter, fuel pressure control is performed by the fuel pressure control means 607 in accordance with the target fuel pressure PO determined in step S606 or step S608.

  As described above, according to the third embodiment, the target fuel pressure at normal return is compared with the basic target fuel pressure, and the condition at which the target fuel pressure at normal return is equal to or higher than the target fuel pressure at normal time, or the actual fuel pressure is compared with a predetermined value. In addition, target fuel pressure switching means that sets the target fuel pressure at the time of normal recovery as the target fuel pressure is provided until any one of the conditions in which the actual fuel pressure is equal to or greater than the predetermined value is established first.

  As a result, when the basic target fuel pressure is low, such as in an idle region, it is possible to appropriately set a fuel pressure increase rate that can reliably prevent deterioration of fuel injection accuracy due to fuel pressure deviation, and when the basic target fuel pressure is high, increase the fuel pressure. The difference between the effective fuel pressure of the fuel injection valve injection timing and the actual fuel pressure (average fuel pressure) during the transition can greatly affect the fuel injection accuracy. It is possible to promptly follow the actual fuel pressure to the basic target fuel pressure in a region where there is little influence of fuel.

Embodiment 4 FIG.
In the fourth embodiment, the control operation of the ECU 60 of the present invention will be specifically described with a comparison with the prior art. FIG. 7 is a time chart showing the operation of fuel injection and fuel discharge control at the time of transition from a fuel system abnormality to normal recovery in a conventional control device. On the other hand, FIG. 8 is a time chart showing the operation of fuel injection and fuel discharge control when the control system corresponding to the first embodiment of the present invention shifts from the fuel system abnormality to the normal return. FIG. 9 is a time chart showing the operation of fuel injection and fuel discharge control when the control system corresponding to the second embodiment of the present invention shifts from abnormal fuel system to normal recovery.

  7 to 9, the vertical axis indicates the fuel injection timing, the fuel system abnormality determination result, the fuel discharge timing of the high-pressure fuel pump 20, and the fuel pressure PF in the accumulator 36 in order from the top. In addition, the horizontal axis indicates the passage of time when shifting from a fuel system abnormality to normal recovery.

  Further, the “intake stroke” and “discharge stroke” described under the fuel discharge timing are annotated that the high-pressure fuel pump 20 is a fuel intake stroke and a discharge stroke, respectively. A period in which the fuel discharge timing is filled with diagonal lines in the discharge stroke indicates a period during which the fuel is actually discharged.

  As shown in FIG. 7, in the conventional control device, the fuel discharge amount controlled by the fuel pressure control means is large because the differential pressure ΔP between the actual fuel pressure PF and the target fuel pressure PO is large when returning from the fuel system abnormality. Increases rapidly. Therefore, the amount of change in the fuel pressure in the actual fuel pressure calculation section is large, and the difference between the effective fuel pressure at the fuel injection valve injection timing at the time when the fuel pressure rises transiently and the actual fuel pressure (average fuel pressure) used for correcting the fuel injection drive time increases. For this reason, in the conventional control device, accurate fuel injection cannot be performed at a transient increase in fuel pressure.

  On the other hand, in the control device for an internal combustion engine in the first embodiment, as shown in FIG. 8, the target fuel pressure POr at the time of normal recovery is set to be higher than the basic target fuel pressure POb for normal recovery from the fuel system abnormal state. A predetermined value on the low pressure side (in this example, a feed pressure) is set, and the target fuel pressure POr at normal return is gradually increased every predetermined period. Until the normal return target fuel pressure POr becomes equal to or higher than the basic target fuel pressure POb, the normal return target fuel pressure POr is set to the target fuel pressure PO and fuel pressure control is performed.

  Therefore, it is possible to appropriately set the fuel pressure increase rate in the transition of the fuel pressure from the feed pressure at the time of normal recovery, and the fuel discharge amount from the high pressure fuel pump 20 is controlled when the target fuel pressure PO is controlled as the basic target fuel pressure POb. Less than Therefore, the amount of change in the fuel pressure in the actual fuel pressure calculation section is suppressed, and the effective fuel pressure (fuel pressure sensor value) at the fuel injection valve injection timing at the time of fuel pressure rise transient and the actual fuel pressure (average fuel pressure) used for fuel injection drive time correction Deviation is suppressed. For this reason, accurate fuel injection can be realized in a transient increase in fuel pressure.

  Further, as shown in FIG. 4, the fuel amount restriction determination means for restricting the injection amount by the fuel cut when it is determined that the fuel injection amount is insufficient after the abnormality determination by the fuel system abnormality determination means. After the fuel system abnormality determining means determines that the fuel has returned to normal, the target fuel pressure switching means continues to determine the fuel injection amount shortage region until the target fuel pressure is switched from the target fuel pressure at normal return to the basic target fuel pressure. For this reason, it is possible to prevent the fuel injection valve drive period from exceeding the injectable period and resulting in lean combustion due to the suppression of the fuel pressure increase during the transition of the fuel pressure increase.

  In the control apparatus for an internal combustion engine according to the second embodiment, as shown in FIG. 9, the normal return target fuel pressure POr until the actual fuel pressure PF becomes equal to or higher than the predetermined value upon normal return from the fuel system abnormal state. Is set to the target fuel pressure PO, and fuel pressure control is performed. For this reason, in the fuel pressure region where the difference between the effective fuel pressure of the fuel injection valve injection timing and the actual fuel pressure (average fuel pressure) at the time of the fuel pressure rise transition greatly affects the fuel injection accuracy, it is possible to reliably prevent deterioration of the fuel injection accuracy due to the fuel pressure shift. At the same time, in the region where the effect of deviation between the effective fuel pressure (fuel pressure sensor value) of the fuel injection valve injection timing at the time of fuel pressure rise transition and the actual fuel pressure (average fuel pressure) used for fuel injection drive time correction is small, The basic target fuel pressure POb determined can be quickly increased.

1 is a configuration diagram schematically showing a control device for an internal combustion engine in Embodiment 1 of the present invention. FIG. It is a functional block diagram of ECU in Embodiment 1 of this invention. It is the flowchart which showed a series of operation | movement of the target fuel pressure switching means in Embodiment 1 of this invention. It is the flowchart which showed a series of operation | movement of the fuel quantity restriction | limiting determination means in Embodiment 1 of this invention. It is the flowchart which showed a series of operation | movement of the target fuel pressure switching means in Embodiment 2 of this invention. It is the flowchart which showed a series of operation | movement of the target fuel pressure switching means in Embodiment 3 of this invention. It is the time chart which showed the operation of fuel injection and fuel discharge control at the time of the transition from the fuel system abnormality in the conventional control device to normal return. 3 is a time chart showing the operation of fuel injection and fuel discharge control at the time of transition from a fuel system abnormality to a normal return in the control device corresponding to Embodiment 1 of the present invention. It is a time chart which showed the operation | movement of the fuel injection and fuel discharge control at the time of transfer to normal recovery from the fuel system abnormality in the control apparatus corresponding to Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow control valve, 11 Solenoid, 20 High pressure fuel pump, 21 Cylinder, 22 Plunger, 23 Pressurization chamber, 24 Cam shaft, 25 Pump cam, 30 Fuel tank, 31 Low pressure fuel pump, 32 Low pressure regulator, 33 Low pressure passage, 34 Fuel Discharge valve, 35 high pressure passage, 36 pressure accumulation chamber, 37 relief valve, 38 relief passage, 39 fuel injection valve, 40 internal combustion engine, 60 ECU, 61 fuel pressure sensor, 62 rotation sensor, 63 accelerator position sensor, 64 intake manifold pressure sensor, 601 Basic target fuel pressure setting means, 602 Fuel pressure averaging means, 603 Fuel system abnormality determination means, 604 Differential pressure calculation means, 605 Target fuel pressure setting means at normal return, 606 Target fuel pressure switching means, 607 Fuel pressure control means, 608 Fuel injection valve drive Time correction means, 609 Fuel injection Control means, PF actual fuel pressure, NE rotation speed, RP rotation position, AP accelerator pedal depression amount, PB intake manifold pressure, POb basic target fuel pressure, POr target fuel pressure at normal return, PO target fuel pressure, ΔP fuel pressure deviation (= PO-PF) , ΔP1 differential pressure (= POb−PF).

Claims (7)

A high-pressure fuel pump that sucks in fuel and discharges pressurized fuel;
A fuel injection valve that directly injects fuel discharged from the high-pressure fuel pump into a cylinder of an internal combustion engine;
Fuel pressure detecting means for detecting the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump;
Fuel pressure averaging means for averaging the fuel pressure detected by the fuel pressure detection means to calculate an actual fuel pressure;
Fuel system abnormality determination means for determining abnormality of the fuel system;
Basic target fuel pressure setting means for setting a basic target fuel pressure according to the operating state of the internal combustion engine;
At the time of normal recovery, the target fuel pressure at normal recovery is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the state where the fuel system abnormality determination means diagnoses that there is an abnormality in the fuel system. Target fuel pressure setting means;
At the time of normal recovery, the normal fuel recovery target fuel pressure set by the normal recovery target fuel pressure setting unit is selected as a target fuel pressure. Thereafter, when a predetermined switching condition is satisfied, the basic target fuel pressure setting unit Target fuel pressure switching means for selecting the set basic target fuel pressure as the target fuel pressure;
Fuel pressure control means for controlling the amount of fuel discharged from the high-pressure fuel pump so that the actual fuel pressure and the target fuel pressure coincide with each other ;
A low pressure fuel pump that pumps fuel in a fuel tank and supplies the fuel adjusted to the feed pressure to the high pressure fuel pump;
With
The control apparatus for an internal combustion engine, wherein the normal return target fuel pressure setting means sets the feed pressure as a predetermined value lower than the basic target fuel pressure at the time of normal return . The control apparatus for an internal combustion engine according to claim 1,
A pressure difference calculating means for calculating a pressure difference between the basic target fuel pressure and the actual fuel pressure;
The normal return target fuel pressure setting means sets a gradual amplification of the normal return target fuel pressure during the normal return based on at least one of the basic target fuel pressure and the differential pressure. Control device. A high-pressure fuel pump that sucks in fuel and discharges pressurized fuel;
A fuel injection valve that directly injects fuel discharged from the high-pressure fuel pump into a cylinder of an internal combustion engine;
Fuel pressure detecting means for detecting the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump;
Fuel pressure averaging means for averaging the fuel pressure detected by the fuel pressure detection means to calculate an actual fuel pressure;
Fuel system abnormality determination means for determining abnormality of the fuel system;
Basic target fuel pressure setting means for setting a basic target fuel pressure according to the operating state of the internal combustion engine;
At the time of normal recovery, the target fuel pressure at normal recovery is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the state where the fuel system abnormality determination means diagnoses that there is an abnormality in the fuel system. Target fuel pressure setting means;
At the time of normal recovery, the normal fuel recovery target fuel pressure set by the normal recovery target fuel pressure setting unit is selected as a target fuel pressure. Thereafter, when a predetermined switching condition is satisfied, the basic target fuel pressure setting unit Target fuel pressure switching means for selecting the set basic target fuel pressure as the target fuel pressure;
Fuel pressure control means for controlling the amount of fuel discharged from the high-pressure fuel pump so that the actual fuel pressure and the target fuel pressure match ,
The target fuel pressure switching means compares the target fuel pressure at normal return with the basic target fuel pressure, and sets a condition that the target fuel pressure at normal return is equal to or higher than the basic target fuel pressure as a predetermined first switching condition. The fuel pressure is compared with a predetermined value, the condition that the actual fuel pressure is equal to or greater than the predetermined value is set as a predetermined second switching condition, and either the predetermined first switching condition or the predetermined second switching condition The control apparatus for an internal combustion engine , wherein the target fuel pressure at the time of normal recovery is selected as the target fuel pressure until the condition is satisfied first . A high-pressure fuel pump that sucks in fuel and discharges pressurized fuel;
A fuel injection valve that directly injects fuel discharged from the high-pressure fuel pump into a cylinder of an internal combustion engine;
Fuel pressure detecting means for detecting the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump;
Fuel pressure averaging means for averaging the fuel pressure detected by the fuel pressure detection means to calculate an actual fuel pressure;
Fuel system abnormality determination means for determining abnormality of the fuel system;
Basic target fuel pressure setting means for setting a basic target fuel pressure according to the operating state of the internal combustion engine;
At the time of normal recovery, the target fuel pressure at normal recovery is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the state where the fuel system abnormality determination means diagnoses that there is an abnormality in the fuel system. Target fuel pressure setting means;
At the time of normal recovery, the normal fuel recovery target fuel pressure set by the normal recovery target fuel pressure setting unit is selected as a target fuel pressure. Thereafter, when a predetermined switching condition is satisfied, the basic target fuel pressure setting unit Target fuel pressure switching means for selecting the set basic target fuel pressure as the target fuel pressure;
Fuel pressure control means for controlling the amount of fuel discharged from the high-pressure fuel pump so that the actual fuel pressure and the target fuel pressure coincide with each other ;
A fuel amount restriction determination means for restricting a fuel amount by a fuel cut when it is determined that the fuel injection amount is insufficient after the abnormality is determined by the fuel system abnormality determination means ;
The fuel amount restriction determination means is determined until the target fuel pressure switching means switches the target fuel pressure from the target fuel pressure at the time of normal return to the basic target fuel pressure after the fuel system abnormality determination means determines that the normal return time is reached. Is a control device for an internal combustion engine, characterized in that the determination of a fuel injection amount shortage region is continued . A high-pressure fuel pump that sucks in fuel and discharges pressurized fuel;
A fuel injection valve that directly injects fuel discharged from the high-pressure fuel pump into a cylinder of an internal combustion engine;
Fuel pressure detecting means for detecting the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump;
Fuel pressure averaging means for averaging the fuel pressure detected by the fuel pressure detection means to calculate an actual fuel pressure;
Fuel system abnormality determination means for determining abnormality of the fuel system;
Basic target fuel pressure setting means for setting a basic target fuel pressure according to the operating state of the internal combustion engine;
At the time of normal recovery, the target fuel pressure at normal recovery is set to gradually increase from a predetermined value lower than the basic target fuel pressure at the time of normal recovery from the state where the fuel system abnormality determination means diagnoses that there is an abnormality in the fuel system. Target fuel pressure setting means;
At the time of normal recovery, the normal fuel recovery target fuel pressure set by the normal recovery target fuel pressure setting unit is selected as a target fuel pressure. Thereafter, when a predetermined switching condition is satisfied, the basic target fuel pressure setting unit Target fuel pressure switching means for selecting the set basic target fuel pressure as the target fuel pressure;
Fuel pressure control means for controlling the amount of fuel discharged from the high-pressure fuel pump so that the actual fuel pressure and the target fuel pressure coincide with each other ;
A fuel amount restriction determination means for restricting a fuel amount by a fuel cut when it is determined that the fuel injection amount is insufficient after the abnormality is determined by the fuel system abnormality determination means ;
The target fuel pressure switching means compares the target fuel pressure at normal return with the basic target fuel pressure, and sets a condition that the target fuel pressure at normal return is equal to or higher than the basic target fuel pressure as a predetermined first switching condition. The fuel pressure is compared with a predetermined value, the condition that the actual fuel pressure is equal to or greater than the predetermined value is set as a predetermined second switching condition, and either the predetermined first switching condition or the predetermined second switching condition Until the condition is established first, select the target fuel pressure at the time of normal return as the target fuel pressure,
The fuel amount restriction determination means is determined until the target fuel pressure switching means switches the target fuel pressure from the target fuel pressure at the time of normal return to the basic target fuel pressure after the fuel system abnormality determination means determines that the normal return time is reached. Is a control device for an internal combustion engine, characterized in that the determination of a fuel injection amount shortage region is continued . The control device for an internal combustion engine according to any one of claims 3 to 5 ,
A pressure difference calculating means for calculating a pressure difference between the basic target fuel pressure and the actual fuel pressure;
The normal return target fuel pressure setting means sets a gradual amplification of the normal return target fuel pressure during the normal return based on at least one of the basic target fuel pressure and the differential pressure. Control device. The control apparatus for an internal combustion engine according to any one of claims 3 to 6 ,
A low-pressure fuel pump that pumps up the fuel in the fuel tank and supplies the fuel adjusted to the feed pressure to the high-pressure fuel pump;
The control device for an internal combustion engine, wherein the normal return target fuel pressure setting means sets the feed pressure as a predetermined value lower than the basic target fuel pressure at the time of normal return.

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