JP2017002892A - Engine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine controller capable of suppressing combustion deterioration of an engine during diagnosis, while securing diagnostic accuracy for abnormality of a fuel pressure sensor.SOLUTION: When an abnormal flag, set in a case where a first abnormality determination condition is established in abnormal diagnosis of a fuel pressure sensor and it is determined that abnormality occurs, is being left in a cleared state (S200:YES), in a case where a state where a fuel pressure detection value of the fuel pressure sensor is constant continues for a specified time T2 or more and a second abnormality determination condition is established (S201:YES), an engine controller prohibits partial lift injection, and performs injection control for a fuel injection valve so as to perform fuel injection without performing the partial lift injection (S210).SELECTED DRAWING: Figure 5

Description

  The present invention relates to an engine control device.

  An electromagnetic fuel injection valve installed in a vehicle-mounted engine is configured to inject fuel by opening a valve body by energizing a built-in electromagnetic solenoid. In an in-cylinder engine or the like, the fuel pumped up from the fuel tank by the feed pump is pressurized by the high-pressure fuel pump and supplied to the fuel injection valve. In such an engine, the injection amount of the fuel injection valve per energization time varies depending on the pressure (fuel pressure) of the fuel supplied from the high-pressure fuel pump to the fuel injection valve. Therefore, as seen in Patent Document 1, a fuel pressure sensor for detecting the fuel pressure is provided, and the energization time of the fuel injection valve is set according to the fuel pressure detected by the fuel pressure sensor.

  On the other hand, in recent years, a partial lift injection technique is known as a technique for realizing high-precision minute quantity injection by the electromagnetic fuel injection valve as described above. The partial lift injection technique is a technique that avoids deterioration of the injection amount accuracy due to the bounce motion of the valve body due to collision when the valve body reaches the fully open position by stopping the injection before the valve body opens to the fully open position. . Such partial lift injection technology is used to improve engine combustion and exhaust properties.

JP 2014-015894 A

  By the way, when the energization time of the fuel injection valve is set based on the detected value of the fuel pressure, if an abnormality occurs in the fuel pressure sensor and the detected value of the fuel pressure deviates from the actual value, the injection amount of the fuel injection valve is also the requested amount. Will deviate from. As a result, the combustion state of the engine may deteriorate, leading to misfire or stall. Therefore, the abnormality of the fuel pressure sensor is diagnosed, and when the abnormality is confirmed, the pressurization operation of the high-pressure fuel pump is stopped as a fail-safe process, and the fuel pumped up by the feed pump is injected without being pressurized. May supply valves.

  However, it takes some time to accurately diagnose the abnormality of the fuel pressure sensor. On the other hand, since the pressure of the fuel supplied to the fuel injection valve becomes a resistance against the lift of the valve body, the lift speed of the valve body and the time until the valve body reaches the fully open position vary depending on the fuel pressure. Therefore, in the partial lift injection that completes the injection within the lift period of the valve body, the influence of the fuel pressure on the injection amount accuracy becomes larger than in the full lift injection. Further, when the combustion state of the engine is ensured by partial lift injection, if the injection amount of partial lift injection is deviated, the combustion state cannot be maintained satisfactorily. Therefore, if an abnormality occurs in the fuel pressure sensor while the engine is operating with partial lift injection, the combustion state will not change until the diagnosis result of the abnormality is confirmed and the fail-safe process is performed. There is a risk of misfire and stalling.

  The present invention has been made in view of such circumstances, and the problem to be solved is an engine control capable of suppressing the deterioration of combustion of the engine under diagnosis while ensuring the accuracy of diagnosis of abnormality of the fuel pressure sensor. To provide an apparatus.

  An engine control device that solves the above problems includes a fuel injection valve that injects fuel by opening a valve body in response to energization, a fuel pump that supplies fuel to the fuel injection valve, and a fuel pump to a fuel injection valve. The present invention is applied to an engine provided with a fuel pressure sensor that detects a fuel pressure that is a pressure of supplied fuel. Then, the control device sets the energization time of the fuel injection valve based on the required injection amount set according to the engine operating state and the detected value of the fuel pressure, and before the valve body opens to the fully open position. And an injection control unit for performing injection control of the fuel injection valve by partial lift injection for stopping injection and full lift injection for stopping injection after the valve body is opened to the fully open position. The engine control device includes a diagnostic unit that determines that the fuel pressure sensor is temporarily abnormal when the second abnormality determination condition is satisfied, and determines that the fuel pressure sensor is abnormal when the first abnormality determination condition is satisfied. The first abnormality determination condition here is set to a condition that is satisfied when an abnormality occurs in the fuel pressure sensor, and the second abnormality determination condition is satisfied when there is a possibility of abnormality of the fuel pressure sensor, and the abnormality of the fuel pressure sensor is detected. At the time of occurrence, a condition that is established before the first abnormality determination condition is set.

  If an abnormality occurs in the fuel pressure sensor and the correct fuel pressure is unknown, the energization time of the fuel injection valve cannot be set appropriately. Therefore, in such a case, fail-safe processing to allow the engine to continue to operate even if the detected value of fuel pressure cannot be acquired normally, processing to notify the driver of the occurrence of abnormality, etc. become.

  However, a certain amount of time is required to accurately diagnose abnormality of the fuel pressure sensor. That is, when the first abnormality determination condition is set so as to increase the diagnostic accuracy, it takes a certain amount of time for the first abnormality determination condition to be satisfied even when an abnormality occurs in the fuel pressure sensor.

  On the other hand, if the injection amount of the partial lift injection shifts due to the difference between the detected value of the fuel pressure and the actual value, the combustion state is greatly affected. For this reason, if an abnormality of the fuel pressure sensor occurs during the execution of partial lift injection, the combustion state may deteriorate until the diagnosis is finalized, resulting in misfire or engine stall.

  Here, in the above control device, the second abnormality determination condition that the diagnosis unit determines as a temporary abnormality of the fuel pressure sensor is established when there is a possibility that the fuel pressure sensor is abnormal, and the first abnormality occurs when the abnormality of the fuel pressure sensor occurs. The condition is established before the determination condition. Therefore, when the abnormality of the fuel pressure sensor has actually occurred, the provisional abnormality is determined before the first abnormality determination condition is satisfied and the abnormality determination of the fuel pressure sensor is finalized. .

  In the above control device, the injection control unit performs the injection control of the fuel injection valve so that the fuel injection is performed without performing the partial lift injection when the diagnosis unit determines that there is a temporary abnormality. That is, even when it is not determined that an abnormality has occurred in the fuel pressure sensor, partial lift injection is prohibited when the occurrence is suspected. Therefore, even when time is required for establishment of abnormality determination of the fuel pressure sensor, deterioration of the combustion state can be suppressed. Therefore, deterioration of combustion of the engine under diagnosis can be suppressed while ensuring the accuracy of diagnosis of abnormality of the fuel pressure sensor.

  In an engine equipped with a high-pressure fuel pump as a fuel pump that pressurizes the fuel pumped up from the fuel tank by the feed pump and supplies it to the fuel injection valve, the control device detects the fuel pressure based on the detected value of the fuel pressure. There may be provided a fuel pressure control unit that controls the operation of the high-pressure fuel pump so that the value becomes the target fuel pressure set according to the engine operating state. In such an engine control device, fail-safe processing when an abnormality occurs in the fuel pressure sensor can be performed, for example, as follows. That is, the fuel pressure control unit stops the pressurizing operation of the high pressure fuel pump when the diagnosis unit determines that the fuel pressure sensor is abnormal. In addition, when the diagnosis unit determines that the fuel pressure sensor is abnormal, the injection control unit sets the energization time of the fuel injection valve using the set value of the feed pressure of the feed pump instead of the detected value of the fuel pressure. When the pressurizing operation of the high pressure fuel pump is stopped, the fuel pumped up by the feed pump is supplied to the fuel injection valve as it is. During operation of the engine, the pressure of the fuel pumped up by the feed pump, that is, the feed pressure, is kept substantially constant. For this reason, the injection control unit at this time uses the set value of the feed pressure of the feed pump instead of the detected value of the fuel pressure to set the energization time of the fuel injection valve, thereby injecting fuel for the required injection amount. The valve can be made to perform.

  By the way, in order to maintain the fuel pressure at the target fuel pressure, it is necessary to control the operation of the high-pressure fuel pump so that the amount of fuel supplied from the high-pressure fuel pump to the fuel injection valve matches the fuel consumption of the fuel injection valve by injection. is there. On the other hand, if an abnormality occurs in the fuel pressure sensor and the detected value of the fuel pressure deviates from the actual value, even if the operation of the high pressure fuel pump is controlled based on the detected value, the fuel supply amount of the fuel injection valve The fuel pressure detection value does not converge to the target fuel pressure because it does not match the fuel consumption. Therefore, the abnormality diagnosis of the fuel pressure sensor is performed by setting the first abnormality determination condition so as to be established when the deviation between the detected value of the fuel pressure and the target fuel pressure continues for a specified abnormality determination time or longer. It can be performed. In addition, in order to determine the abnormality of the fuel pressure sensor at this time with high accuracy, it is necessary to set the abnormality determination time to a relatively long time.

  On the other hand, as an abnormality of the fuel pressure sensor, there is a stack abnormality in which the sensor output and thus the detected value of the fuel pressure becomes constant. For this reason, the second abnormality determination condition may be set so as to be satisfied when a state in which the detection value of the fuel pressure is constant continues for a predetermined time or longer. Incidentally, in this case, it is not necessary to determine the stack abnormality, and it is only necessary to determine whether or not the occurrence of the stack is suspected. Therefore, the specified time may be a relatively short time. If the state in which the detected value of the fuel pressure is constant continues further beyond the specified time, the stack abnormality of the fuel pressure sensor will eventually become definite. Therefore, a time longer than the specified time when the second abnormality determination condition is satisfied is set as the stack abnormality determination time, and the first abnormality is set so as to be satisfied when the state where the detection value of the fuel pressure is constant continues for the same stack abnormality determination time. If one abnormality determination condition is set, it is possible to diagnose a stack abnormality of the fuel pressure sensor.

  In addition, if the engine is operated in a state where an abnormality occurs in the fuel pressure sensor and the detected value deviates from the actual value, there is a possibility that engine stall may occur. Therefore, the second abnormality determination condition may be set so as to be established when an engine stall occurs. If the combustion is greatly deteriorated due to the abnormality of the fuel pressure sensor, it is considered that the engine operation cannot be continued for the time required for the abnormality diagnosis by the diagnosis unit. In such a case, even if the engine is restarted, the engine stall may occur again before the abnormality diagnosis by the diagnosis unit is completed. Therefore, even if the engine is restarted many times, the result of the abnormality diagnosis may not be determined. There is. In that regard, if partial lift injection is prohibited when an engine stall occurs, fuel deterioration after engine restart can be suppressed. Therefore, even when the combustion of the engine deteriorates until the engine stall occurs due to the abnormality of the fuel pressure sensor, the abnormality of the fuel pressure sensor is easily diagnosed.

  Further, the engine control includes an air-fuel ratio control unit that corrects the required injection amount so that the detected value of the air-fuel ratio becomes the target air-fuel ratio based on the detected value of the air-fuel ratio sensor that detects the air-fuel ratio of the air-fuel mixture burned by the engine In the apparatus, if the injection amount of the fuel injection valve deviates from the required injection amount due to the abnormality of the fuel pressure sensor, the air-fuel ratio cannot be converged to the target air-fuel ratio, and the correction amount of the required injection amount by the air-fuel ratio control unit is absolute. The value can be large. Therefore, in the engine control device including such an air-fuel ratio control unit, the second abnormality determination condition is set so as to be satisfied when the absolute value of the correction amount of the required injection amount by the air-fuel ratio control unit is equal to or greater than a specified value. May be.

  In the engine control device, the injection control unit performs multi-stage injection that divides the fuel for the required injection amount into multiple injections when the first abnormality determination condition is not satisfied and the second abnormality determination condition is satisfied. It is desirable to ban. The deviation of the fuel injection amount due to the difference between the detected fuel pressure value by the fuel pressure sensor and the actual fuel pressure is more than the amount of fuel required for the required injection amount than when the fuel for the required injection amount is injected by one fuel injection. The case where it divides | segments into times and injects becomes larger. For this reason, by prohibiting multi-stage injection in a situation where the occurrence of an abnormality in the fuel pressure sensor is suspected, it is possible to reduce the deviation in the fuel injection amount when the detected value of the fuel pressure cannot be obtained normally, and in turn the combustion of the engine due to that deviation. Deterioration can be suppressed.

  During idle operation of the warming-up engine of the catalyst device for purifying exhaust gas, multistage injection of fuel injection during the intake stroke by full lift injection and fuel injection during the compression stroke by partial lift injection is performed, and partial lift injection By collecting the injected fuel around the spark plug, it is possible to stabilize the combustion at the cold start when the fuel is hard to vaporize. In such a case, the shift in the injection amount of the partial lift injection during the compression stroke directly leads to deterioration of combustion. Therefore, the engine control device has a more remarkable effect when performing such multi-stage injection.

  By the way, a high-pressure fuel pump that pressurizes the fuel pumped up from the fuel tank by the feed pump is provided as the fuel pump, and an in-cylinder injection valve that injects fuel supplied from the high-pressure fuel pump into the cylinder is provided as the fuel injection valve. Separately, there is an engine provided with a port injection valve that injects fuel supplied from a feed pump into an intake port without going through a high-pressure fuel pump. In such an engine, when the partial lift injection of the in-cylinder injection valve is prohibited, the fuel injection can be performed by the fuel injection by the full lift injection of the in-cylinder injection valve and the fuel injection by the port injection valve. . On the other hand, if an abnormality occurs in the fuel pressure sensor, the fuel pressure in the high-pressure fuel pipe cannot be properly controlled, and the fuel pressure cannot be confirmed. Therefore, when an abnormality occurs in the fuel pressure sensor, the fuel pressure in the high-pressure fuel pipe may be significantly lower than required. When the fuel pressure in the high-pressure fuel pipe decreases, the injection pressure of fuel injection by the in-cylinder injection valve also decreases, and during high load operation in which the in-cylinder pressure during injection increases, fuel injection by the in-cylinder injection valve is insufficient. May become impossible. Even in such a case, when the partial lift injection is prohibited, the injection control unit in the engine control device performs the fuel injection by the full lift injection of the port injection valve when the engine load factor is equal to or higher than the specified value. If fuel injection is performed by full lift injection of the in-cylinder injection valve when it is less than the specified value, even if the fuel pressure in the high-pressure fuel pipe is low, fuel injection becomes impossible due to insufficient injection pressure Can be avoided.

1 is a schematic diagram schematically showing the configuration of an engine to which a first embodiment of an engine control device is applied. Sectional drawing of the cylinder injection valve provided in the fuel supply system. The graph which shows the relationship between the injection amount of the same cylinder injection valve, its variation, and energization time. The flowchart of the abnormality determination routine performed in the engine control apparatus of 1st Embodiment. The flowchart of the P / L injection prohibition determination routine performed in the same control apparatus. The flowchart of the injection mode determination routine performed in the control apparatus. The flowchart of the P / L injection prohibition determination routine performed in the engine control apparatus of 2nd Embodiment. The flowchart of the P / L injection prohibition determination routine performed in the engine control apparatus of 3rd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of an engine control device will be described in detail with reference to FIGS.
As shown in FIG. 1, an air cleaner 12, an air flow meter 13, a throttle valve 14, and an intake manifold 11 </ b> A are provided in order from the upstream side in an intake passage 11 of an engine 10 to which the control device of the present embodiment is applied. . The air cleaner 12 filters dust in the intake air flowing into the intake passage 11, the air flow meter 13 detects the flow rate of intake air (intake air amount GA), and the throttle valve 14 sucks in through the change of the valve opening. Adjust the air volume. The intake passage 11 is branched in the intake manifold 11A and then connected to each cylinder 16 through an intake port 15 for each cylinder.

  On the other hand, in the exhaust passage 17 of the engine 10, an exhaust manifold 17A, an air-fuel ratio sensor 18, and a catalyst device 19 are provided in order from the upstream side. The exhaust discharged from each cylinder 16 to the exhaust passage 17 is merged in the exhaust manifold 17A, flows into the catalyst device 19, and is purified in the catalyst device 19. The air-fuel ratio sensor 18 outputs a signal corresponding to the air-fuel ratio at the time of combustion of the exhaust gas flowing into the catalyst device 19.

  Such a fuel supply system of the engine 10 includes a feed pump 21 that pumps and discharges fuel in the fuel tank 20. The feed pump 21 is connected to a low pressure fuel pipe 23 and a high pressure fuel pump 24 via a low pressure fuel passage 22. The low-pressure fuel pipe 23 is a fuel container that stores fuel sent from the feed pump 21, and is connected to the port injection valve 25 of each cylinder 16 of the engine 10. The port injection valve 25 is configured as an electromagnetic fuel injection valve that injects fuel stored in the low-pressure fuel pipe 23 into the intake port 15 of the engine 10 in response to energization. On the other hand, the high-pressure fuel pump 24 further pressurizes the fuel sent from the feed pump 21 and discharges it to the high-pressure fuel pipe 26. The low-pressure fuel passage 22 opens when the fuel pressure (feed pressure) in the low-pressure fuel passage 22 exceeds a specified relief pressure by a filter 27 that filters the fuel discharged from the feed pump 21 and the low-pressure fuel passage 22 opens. A pressure regulator 28 for relieving the fuel in the passage 22 into the fuel tank 20 is provided.

  In the high-pressure fuel pump 24, two volume portions of a fuel gallery 29 and a pressurizing chamber 30 are provided. Fuel sent from the feed pump 21 through the low-pressure fuel passage 22 is introduced into the fuel gallery 29. In the fuel gallery 29, a pulsation damper for attenuating the pulsation of the fuel pressure is provided. Further, the high-pressure fuel pump 24 is provided with a plunger 34 which is reciprocated by a pump driving cam 33 provided on the cam shaft 32 of the engine 10 to change the volume of the pressurizing chamber 30.

  The fuel gallery 29 and the pressurizing chamber 30 are connected via an electromagnetic spill valve 35. The electromagnetic spill valve 35 is a normally open valve that closes in response to energization, and communicates the fuel gallery 29 and the pressurizing chamber 30 when the valve is opened, and blocks the communication when the valve is closed. Further, the pressurizing chamber 30 communicates with the high-pressure fuel pipe 26 through the check valve 36. The check valve 36 opens when the pressure in the pressurization chamber 30 becomes higher than that in the high-pressure fuel pipe 26, and allows fuel discharge from the pressurization chamber 30 to the high-pressure fuel pipe 26. The valve is closed when the pressure inside the pressurized chamber 30 becomes higher than that in the pressurized chamber 30 to restrict the back flow of fuel from the high pressure fuel pipe 26 to the pressurized chamber 30.

  The high-pressure fuel pipe 26 is a fuel container that stores high-pressure fuel sent from the high-pressure fuel pump 24, and an in-cylinder injection valve 37 installed in each cylinder 16 of the engine 10 is connected to the high-pressure fuel pipe 26. The in-cylinder injection valve 37 is configured as an electromagnetic fuel injection valve that injects fuel stored in the high-pressure fuel pipe 26 into the cylinder 16 in response to energization. A fuel pressure sensor 38 for detecting the internal fuel pressure (high pressure side fuel pressure) is attached to the high pressure fuel pipe 26. The high-pressure fuel pipe 26 is also provided with a relief valve 39A that opens when the internal pressure is excessively increased and relieves the internal fuel into the fuel tank 20 through the relief passage 39. .

  Further, the engine fuel supply system includes an electronic control unit 40. The electronic control unit 40 temporarily stores a central processing unit that performs various arithmetic processing, a read-only memory in which programs and data for the arithmetic processing are stored in advance, arithmetic results of the central processing unit, detection results of various sensors, and the like. A readable memory is provided for automatic storage. The electronic control unit 40 includes a nonvolatile memory for storing and holding data even when the power is turned off.

  The electronic control unit 40 includes a crank angle sensor 41 that detects the rotational phase (crank angle) of the crankshaft of the engine 10 in addition to the air flow meter 13, the air-fuel ratio sensor 18, and the fuel pressure sensor 38, and a driver's accelerator pedal. A detection signal of a sensor such as an accelerator pedal sensor 42 for detecting the depression amount of the pedal is input. The electronic control unit 40 performs energization control of the electromagnetic spill valve 35, the port injection valve 25, and the in-cylinder injection valve 37 of the high-pressure fuel pump 24 based on the detection results of these sensors. The electronic control unit 40 calculates the engine speed NE from the detection result of the crank angle sensor 41 and calculates the engine load factor KL from the detection results of the air flow meter 13 and the accelerator pedal sensor 42. The engine load factor KL represents a ratio of the current cylinder inflow air amount when the maximum value of the cylinder inflow air amount at the current engine speed NE in natural intake is set to “100%”. Used as an index value.

<Variable fuel pressure control>
The electronic control unit 40 performs variable control of the fuel pressure (high-pressure side fuel pressure) in the high-pressure fuel pipe 26 through energization control of the electromagnetic spill valve 35 of the high-pressure fuel pump 24. First, the pressurizing operation of the high-pressure fuel pump 24 will be described. In the following description, the movement of the plunger 34 in the direction of reducing the volume of the pressurizing chamber 30 is referred to as “up”, and the movement of the plunger 34 in the direction of increasing the volume of the pressurizing chamber 30 is referred to as “down”.

  The fuel discharged from the feed pump 21 is introduced into the fuel gallery 29 of the high pressure fuel pump 24 through the low pressure fuel passage 22. Here, when the plunger 34 is lowered while the electromagnetic spill valve 35 is open, the fuel is sucked into the pressurizing chamber 30 from the fuel gallery 29 in accordance with the expansion of the volume of the pressurizing chamber 30. Thereafter, when the plunger 34 changes from descending to ascending, the volume of the pressurizing chamber 30 gradually decreases. If the electromagnetic spill valve 35 remains open at this time, the fuel is returned from the pressurizing chamber 30 to the fuel gallery 29 in accordance with the reduction of the volume. When energization to the electromagnetic spill valve 35 is started while the plunger 34 is raised, the electromagnetic spill valve 35 is closed and the pressurizing chamber 30 is sealed. Therefore, the fuel pressure in the pressurizing chamber 30 increases as the volume decreases. When the fuel pressure in the pressurizing chamber 30 becomes higher than the fuel pressure in the high-pressure fuel pipe 26, the check valve 36 is opened, and the fuel in the pressurizing chamber 30 that has become high pressure is pumped to the high-pressure fuel pipe 26. Thereafter, if energization to the electromagnetic spill valve 35 is stopped when the plunger 34 changes from rising to lowering, the fuel is again sucked into the pressurizing chamber 30 from the fuel gallery 29. The high-pressure fuel pump 24 supplies fuel to the high-pressure fuel pipe 26 by repeating the suction of the fuel when the plunger 34 is lowered and the pressurized discharge of the fuel when the plunger 34 is raised.

  The amount of fuel discharged by the high-pressure fuel pump 24 each time the plunger 34 is moved up and down once (hereinafter referred to as the fuel discharge amount of the high-pressure fuel pump 24) is an electromagnetic spill valve during the ascending period of the plunger 34. It increases if the start time of energization to 35 is advanced, and decreases if it is delayed. The electronic control unit 40 performs fuel pressure variable control that makes the fuel pressure in the high-pressure fuel pipe 26 variable by adjusting the energization start timing of the electromagnetic spill valve 35.

  In the variable fuel pressure control, the electronic control unit 40 first calculates a target fuel pressure Pt that is a target value of the fuel pressure in the high-pressure fuel pipe 26 based on the engine load factor KL and the like. The target fuel pressure Pt is basically set to a low pressure when the engine load factor KL is low and to a high pressure when the engine load factor KL is high.

  Then, the electronic control unit 40 determines that the fuel pressure detection value Pm is the target fuel pressure according to the deviation between the fuel pressure detection value (hereinafter referred to as fuel pressure detection value Pm) in the high-pressure fuel pipe 26 by the fuel pressure sensor 38 and the target fuel pressure Pt. The energization start timing of the electromagnetic spill valve 35 during the ascending period of the plunger 34 is adjusted so as to approach Pt. Specifically, when the detected fuel pressure value Pm is lower than the target fuel pressure Pt, the energization start timing of the electromagnetic spill valve 35 is advanced to increase the fuel discharge amount of the high-pressure fuel pump 24. When the detected fuel pressure value Pm is higher than the target fuel pressure Pt, the energization start timing of the electromagnetic spill valve 35 is delayed to reduce the fuel discharge amount of the high-pressure fuel pump 24. Thus, the electronic control unit 40 keeps the fuel pressure in the high-pressure fuel pipe 26 at the target fuel pressure Pt.

<Fuel injection control>
The electronic control unit 40 also controls fuel injection by the port injection valve 25 and the in-cylinder injection valve 37. The fuel injection control is performed in the following manner.

  In the fuel injection control, the electronic control unit 40 first calculates the required injection amount Qt based on the operating state of the engine 10 (engine speed NE, engine load factor KL, etc.). The required injection amount Qt is a required value of the total amount of fuel injected per combustion cycle in each cylinder. Further, the electronic control unit 40 determines the injection ratio of the port injection valve 25 and the in-cylinder injection valve 37 based on the operating state of the engine 10. The electronic control unit 40 determines the required injection amount Qt according to the injection ratio, the port injection amount Qp, which is the amount of fuel injected by the port injection valve 25, and the amount of fuel injected by the in-cylinder injection valve 37. Is allocated to the in-cylinder injection amount Qd. Further, the electronic control unit 40 sets the energization time of the port injection valve 25 necessary for fuel injection for the port injection amount Qp and the energization time of the in-cylinder injection valve 37 necessary for fuel injection for the in-cylinder injection amount Qd, respectively. Calculate. The electronic control unit 40 is configured to energize the port injection valve 25 and the in-cylinder injection valve 37 for each calculated energization time.

  Note that, as described above, the fuel pressure in the high-pressure fuel pipe 26 that supplies fuel to the in-cylinder injection valve 37 is variably controlled. When the fuel pressure changes, the amount of fuel injected by the in-cylinder injection valve 37 per unit time changes depending on the energization. Therefore, regarding the energization time of the in-cylinder injection valve 37, the fuel pressure detection value Pm of the fuel pressure sensor 38 is referred to, and the fuel corresponding to the in-cylinder injection amount Qd is obtained when the fuel pressure in the high-pressure fuel pipe 26 is the fuel pressure detection value Pm. The energization time required for injection is calculated.

<Partial lift injection>
Incidentally, the in-cylinder injection valve 37 that injects higher pressure fuel injects more fuel in a short period of time compared to the port injection valve 25 that injects lower pressure fuel. In such an in-cylinder injection valve 37, the following structural problem greatly affects the injection amount accuracy in a small amount of fuel injection.

FIG. 2 shows a cross-sectional structure of the cylinder injection valve 37. In the following description, the lower side in the figure is referred to as the front end side of the cylinder injection valve 37.
As shown in the figure, an electromagnetic solenoid 51 is built in the housing 50 of the in-cylinder injection valve 37. The electromagnetic solenoid 51 includes a fixed core 52 fixed to the housing 50, an electromagnetic coil 53 provided around the fixed core 52, and a movable core 54 provided adjacent to the fixed core 52 on the distal end side. . The movable core 54 is installed in the housing 50 so as to be displaceable in the vertical direction in the figure, and the valve body 55 is integrally connected so as to be displaceable. Further, a spring 56 that urges the movable core 54 toward the distal end side is also provided in the housing 50.

  On the other hand, a nozzle body 57 is attached to the front end portion of the housing 50 so as to surround the periphery of the front end portion of the valve body 55. A slit-like injection hole 58 that communicates the inside and the outside of the nozzle body 57 is formed at the tip of the nozzle body 57. A fuel chamber 59 into which the fuel sent from the high pressure fuel pipe 26 is introduced is formed inside the housing 50.

  In such an in-cylinder injection valve 37, the valve body 55 is urged toward the distal end side together with the movable core 54 by a spring 56. When the electromagnetic solenoid 51 is not energized, the urging force of the spring 56 causes the valve body 55 to be displaced to a position where it is seated on the nozzle body 57 (hereinafter referred to as a fully closed position). The hole 58 is closed.

  When energization of the electromagnetic solenoid 51 is started, an electromagnetic attractive force is generated between the fixed core 52 and the movable core 54, and the valve body 55 is displaced together with the movable core 54 toward the side closer to the fixed core 52. As a result, when the tip of the valve body 55 leaves the nozzle body 57, the injection hole 58 is opened, and the fuel in the fuel chamber 59 is injected to the outside. The valve body 55 is displaceable to a position where the movable core 54 abuts the fixed core 52 (hereinafter referred to as a fully opened position) with respect to the side where the tip is separated from the nozzle body 57.

  Thereafter, when energization to the electromagnetic solenoid 51 is stopped, the valve body 55 is displaced toward the fully closed position. When the valve body 55 reaches the fully closed position, the injection hole 58 is closed and fuel injection is stopped. In the following description, the bed leaving amount at the tip of the valve body 55 with respect to the nozzle body 57 is described as the nozzle lift amount of the in-cylinder injection valve 37.

  FIG. 3 shows the relationship between the injection amount of the in-cylinder injection valve 37 and its variation, and the energization time for the electromagnetic solenoid 51. In the figure, “T0” indicates the energization time (lift start energization time) required for starting the bed 55 (lift) of the valve body 55 from the nozzle body 57, and “Tpmax” indicates that the valve body 55 is fully opened. The energization time (P / L maximum energization time) required for reaching is shown respectively.

  In the section from “T0 to Tpmax”, the nozzle lift amount changes during energization, so the rate of change of the injection amount of the in-cylinder injection valve 37 with respect to the energization time becomes relatively large. On the other hand, in the section after “Tpmax”, the nozzle lift amount is maintained at the fully opened amount, so the rate of change of the injection amount of the in-cylinder injection valve 37 with respect to the energization time is compared with the section from “T0 to Tpmax”. And get smaller. In the following description, a section from “T0 to Tpmax” where the valve body 55 does not fully open is described as a partial lift (P / L) section. Further, a section after “Tpmax” in which the valve element 55 is fully opened is referred to as a full lift (F / L) section.

  There is some variation in the time from the start of energization to the start of lift of the valve body 55 (lift start energization time T0), and this variation causes the variation in the injection amount in the P / L section. However, since the effect of the variation in the lift start energization time T0 on the variation in the injection amount becomes relatively small as the injection amount increases, the variation in the injection amount in the P / L section decreases as the energization time increases. To do.

  On the other hand, when the valve body 55 in which the movable core 54 comes into contact with the fixed core 52 reaches the fully open position, the valve body 55 bounces due to the reaction of the collision between the movable core 54 and the fixed core 52. The minute vibration of the nozzle lift amount due to the bounce motion increases the variation in the injection amount. The influence that the bounce motion of the valve body 55 at the time of full opening has on the variation in the injection amount also becomes relatively small as the injection amount increases. Therefore, the variation in the injection amount of the in-cylinder injection valve 37 once increases immediately after entering the F / L section, and then decreases as the energization time increases. Therefore, if the fuel injection is performed with the energization time set longer than the specified time (F / L minimum energization time Tfmin) longer than the P / L maximum energization time Tpmax, the variation in the injection amount can be suppressed to an allowable value or less. It becomes possible.

  On the other hand, as described above, also in the P / L section, the variation in the injection amount is relatively small during the energization time immediately before entering the F / L section. Therefore, even if the energization time is set to a range not less than the specified time (P / L minimum energization time Tpmin) and less than the P / L maximum energization time Tpmax, the variation in the injection amount can be suppressed to an allowable value or less. In the present embodiment, by setting the energization time in such a range and performing fuel injection in which the valve body 55 does not reach full open, so-called partial lift injection, a very small amount of fuel injection by the in-cylinder injection valve 37 is high injection. It is done with quantity accuracy. Incidentally, in contrast to such partial lift injection, fuel injection in which the valve body 55 is fully opened is referred to as full lift injection.

  Incidentally, the port injection valve 25 has the same structural problem. However, even when the port injection amount Qp is the lower limit value of the control range, the energization time of the port injection valve 25 is longer than the F / L minimum energization time Tfmin of the port injection valve 25. All the fuel injections are performed by full lift injection in which the valve body is fully opened.

<Catalyst warm-up promotion control>
In the engine control device of the present embodiment, the electronic control unit 40 performs catalyst warm-up promotion control for promoting warm-up of the catalyst device 19 when the engine 10 is cold started. In such catalyst warm-up promotion control, partial lift injection is performed.

  Specifically, in the catalyst warm-up promotion control, the fuel injection when the engine 10 is idling while the catalyst device 19 has not been warmed up is in the intake stroke by the full lift injection of the in-cylinder injection valve 37. And the fuel injection during the compression stroke by the partial lift injection of the in-cylinder injection valve 37 as well. The fuel injected during the compression stroke by the partial lift injection at this time rides on the in-cylinder airflow and is carried to the vicinity of the spark plug. As a result, an air-fuel mixture in which the fuel concentration in the area around the spark plug is locally increased is formed in the cylinder, so that the cylinder wall temperature is low and the fuel is hard to vaporize. It is said. And thereby, exhaust temperature is raised and the temperature rise of the catalyst apparatus 19 is accelerated | stimulated.

<Abnormal diagnosis of fuel pressure sensor>
As described above, the fuel injection by the in-cylinder injection valve 37 calculates the energization time during which fuel corresponding to the in-cylinder injection amount Qd can be injected based on the fuel pressure detection value Pm by the fuel pressure sensor 38, and It is executed by energizing the electromagnetic solenoid 51 for the calculated energization time. Therefore, when an abnormality occurs in the fuel pressure sensor 38 and the detected fuel pressure value Pm shows a value deviating from the actual fuel pressure in the high-pressure fuel pipe 26, the amount of fuel actually injected by the in-cylinder injection valve 37. However, there is a risk of deteriorating combustion by deviating from the requested in-cylinder injection amount Qd.

  On the other hand, as described above, the detected fuel pressure value Pm of the fuel pressure sensor 38 is also used for variable fuel pressure control. That is, in the variable fuel pressure control, the pressurizing operation of the high-pressure fuel pump 24 is controlled so that the detected fuel pressure value Pm is the target fuel pressure Pt. If an abnormality occurs in the fuel pressure sensor 38, the fuel pressure detection value Pm cannot be converged to the target fuel pressure Pt by the fuel pressure variable control. Therefore, in the present embodiment, when the state in which the deviation between the fuel pressure detection value Pm and the target fuel pressure Pt is equal to or greater than the specified value continues for the specified abnormality determination time T1 or longer, it is determined that “abnormality exists”. An abnormality diagnosis is performed. That is, in the present embodiment, the first abnormality determination condition is set so as to be satisfied when a state where the deviation between the fuel pressure detection value Pm and the target fuel pressure Pt is equal to or greater than a predetermined value continues for a predetermined abnormality determination time T1. When the first abnormality determination condition is satisfied, it is determined that the fuel pressure sensor 38 is abnormal.

  Even when the abnormality of the fuel pressure sensor 38 has not occurred, the deviation of the detected fuel pressure value Pm from the target fuel pressure Pt may temporarily occur. Therefore, in order to avoid erroneous determination and ensure high diagnostic accuracy, it is necessary to set a certain long time as the abnormality determination time T1.

<Fail-safe treatment>
In the present embodiment, the following processing is performed as fail-safe processing when it is determined that the fuel pressure sensor 38 is abnormal. That is, (a) stopping the pressurizing operation of the high-pressure fuel pump 24 and (b) switching the calculation mode of the energization time of the in-cylinder injection valve 37 are performed as fail-safe processing.

  FIG. 4 shows a flowchart of an abnormality determination routine executed for the abnormality diagnosis and fail-safe processing. The processing of this routine is repeatedly executed by the electronic control unit 40 at regular control cycles while the engine 10 is in operation.

  When the processing of this routine is started, it is first determined in step S100 whether or not the first abnormality determination condition is satisfied. That is, it is determined whether or not the state where the deviation (absolute value) between the fuel pressure detection value Pm and the target fuel pressure Pt is equal to or greater than the specified value α continues for the abnormality determination time T1. Here, if the first abnormality determination condition is not satisfied (NO), the process of this routine is terminated as it is. On the other hand, if the first abnormality determination condition is satisfied (YES), the process proceeds to step S120.

  When the process proceeds to step S120, an abnormality flag is set in step S120. The abnormality flag is a flag that is set when the occurrence of abnormality in the fuel pressure sensor 38 is confirmed, and the value thereof is stored in the nonvolatile memory of the electronic control unit 40. When the electronic control unit 40 is assembled to the engine 10, the abnormality flag is cleared. Once the electronic control unit 40 is set, the abnormality flag is maintained until the repair inspection at the repair shop is completed. At this time, an indicator for notifying the driver of the occurrence of an abnormality is turned on, and a history that an abnormality has occurred in the fuel pressure sensor 38 is recorded in the nonvolatile memory of the electronic control unit 40.

  Subsequently, in step S121 and step S122, after the fail-safe process is performed, the process of this routine is terminated. That is, after the pressurization operation of the high-pressure fuel pump 24 is stopped in step S121, the energization time of the in-cylinder injection valve 37 is set so that the feed pressure set value Pf is used instead of the fuel pressure detection value Pm in step S122. The calculation mode is switched. Incidentally, as will be described later, in the fail-safe process, partial lift injection is also prohibited.

  If the fail safe process has already been performed at the time when the process proceeds to step S121, the execution is continued as it is. That is, the pressurization operation of the high-pressure fuel pump 24 is stopped, and the calculation of the energization time of the in-cylinder injection valve 37 using the feed pressure set value Pf instead of the fuel pressure detection value Pm is continued.

<Prohibition of partial lift injection>
By the way, in the cylinder injection valve 37 as described above, the fuel pressure in the fuel chamber 59 acts as a drag force against the lift of the valve body 55 and greatly affects the valve opening operation of the valve body 55. In the partial lift injection that completes the injection within the lift period of the valve body 55, the influence of the fuel pressure on the injection amount accuracy becomes larger than in the full lift injection. Further, when the combustion state of the engine 10 is ensured by partial lift injection, if a deviation occurs in the injection amount of partial lift injection, the combustion state cannot be maintained satisfactorily.

  On the other hand, as described above, an accurate abnormality diagnosis of the fuel pressure sensor 38 requires a certain amount of time, and an abnormality occurs during the period from the occurrence of the abnormality until the diagnosis result is confirmed and the fail-safe process is started. The energization time of the in-cylinder injection valve 37 is calculated based on the inaccurate fuel pressure detection value Pm of the fuel pressure sensor 38. Therefore, if an abnormality occurs in the fuel pressure sensor 38 during execution of partial injection, there is a possibility that the combustion state deteriorates and misfire or stall occurs during the period until the failsafe process is started.

  In the present embodiment, such a problem is addressed by performing P / L injection inhibition control described below. Specifically, the P / L prohibition control is a condition that is established when there is a possibility of abnormality of the fuel pressure sensor 38, and is established before the first abnormality determination condition when an abnormality occurs in the fuel pressure sensor 38. The condition is set as the second abnormality determination condition. When the second abnormality determination condition is satisfied, partial lift injection is prohibited. That is, when the second abnormality determination condition is satisfied, the injection control of the in-cylinder injection valve 37 and the port injection valve 25 is performed so that fuel injection is performed without performing partial lift injection.

  In the present embodiment, such a second abnormality determination condition is set so as to be satisfied when a state in which the fuel pressure detection value Pm of the fuel pressure sensor 38 is constant continues for a specified time T2 or more. This is due to the following reason.

  One abnormality of the fuel pressure sensor 38 is a stack abnormality in which the sensor output becomes constant. When such a stack abnormality occurs, the fuel pressure detection value Pm remains constant and does not change. Therefore, when the fuel pressure detection value Pm of the fuel pressure sensor 38 is kept constant, there is a possibility that a stack abnormality has occurred. In the P / L injection prohibition control, it is not necessary to determine the stack abnormality, and it is only necessary to detect that the occurrence is suspected. Therefore, a time shorter than the abnormality determination time T1 is set as the specified time T2.

  FIG. 5 shows a flowchart of a P / L injection prohibition determination routine that is executed to determine whether or not P / L injection is prohibited in such P / L injection prohibition control. The processing of this routine is repeatedly executed by the electronic control unit 40 at regular control cycles while the engine 10 is in operation.

  When this routine is started, it is first determined in step S200 whether or not the abnormality flag is cleared. That is, it is determined whether or not it is determined that there is an abnormality in the fuel pressure sensor 38. If the abnormality flag is set, that is, if the diagnosis result that the fuel pressure sensor 38 is abnormal has already been determined (NO), the process proceeds to step S210. In step S210, partial lift injection is prohibited. That is, at the time of performing the fail-safe process, in addition to stopping the pressurizing operation of the high-pressure fuel pump 24 and switching the calculation mode of the energization time of the in-cylinder injection valve 37, the partial lift injection is also prohibited.

  On the other hand, if the abnormality flag is cleared (S200: YES), the process proceeds to step S201. In step S201, whether the fuel pressure detection value Pm of the fuel pressure sensor 38 is constant or longer than the specified time T2. It is determined whether or not. Here, when an affirmative determination is made, that is, when it is determined that the second abnormality determination condition is satisfied (YES), the process proceeds to step S210 and partial lift injection is prohibited. On the other hand, when a negative determination is made (NO), the process proceeds to step S211, and partial lift injection is permitted.

  FIG. 6 shows a flowchart of an injection mode determination routine for determining the mode of fuel injection by the in-cylinder injection valve 37 and the port injection valve 25 based on the determination result in the P / L injection prohibition determination routine. The processing of this routine is repeatedly executed by the electronic control unit 40 at regular control cycles while the engine 10 is in operation.

  When the processing of this routine is started, first, in step S300, it is determined whether or not partial lift injection is prohibited in the P / L injection prohibition determination routine. If partial lift injection is not prohibited, that is, if partial lift injection is permitted (NO), the processing of this routine is terminated as it is. In this case, the above-described fuel injection control is performed as it is, and multistage injection including partial lift injection of the in-cylinder injection valve 37 is performed as necessary.

  On the other hand, if the partial lift injection is prohibited (YES), it is determined in step S301 whether or not the engine load factor KL is equal to or greater than a specified value γ. The prescribed value γ is the upper limit value of the range of the engine load factor KL that can execute the fuel injection by the in-cylinder injection valve 37 even when the injection pressure of the fuel injection by the in-cylinder injection valve 37 is reduced to the feed pressure. Is set.

  If the engine load factor KL is greater than or equal to the specified value γ (YES), after it is determined in step S302 that fuel injection is to be performed by one port injection by the port injection valve 25, Processing is terminated. On the other hand, when the engine load factor KL is less than the specified value γ (NO), after it is determined in step S303 that fuel injection is performed by one in-cylinder injection by full lift injection of the in-cylinder injection valve 37, this time This routine is finished. That is, when partial lift injection is prohibited, multistage injection is prohibited, and fuel injection is performed by one port injection or one in-cylinder injection.

<Action>
Then, the effect | action of this embodiment comprised as mentioned above is demonstrated.
In the present embodiment, based on the fuel pressure detection value Pm of the fuel pressure sensor 38, fuel pressure variable control for controlling the operation of the high-pressure fuel pump 24 so that the fuel pressure detection value Pm becomes the target fuel pressure Pt set according to the engine operating state. Has been done. Therefore, if an abnormality occurs in the fuel pressure sensor 38 and the detected fuel pressure value Pm becomes an inaccurate value, the variable fuel pressure control based on that value is not properly performed, and the detected fuel pressure value Pm deviates from the target fuel pressure Pt. It becomes like this.

  In the present embodiment, when the deviation between the fuel pressure detection value Pm and the target fuel pressure Pt continues for a specified abnormality determination time T1 or longer for a predetermined abnormality determination time T1, the first abnormality determination condition is satisfied and the fail-safe process is performed. . In the fail-safe process, the energization of the electromagnetic solenoid 51 is held in a stopped state, and the pressurizing operation of the high-pressure fuel pump 24 is stopped. Further, the calculation mode of the energization time of the in-cylinder injection valve 37 is switched so that the energization time is calculated using the feed pressure set value Pf instead of the fuel pressure detection value Pm. Further, when the fail-safe process is performed, fuel injection by partial lift injection of the in-cylinder injection valve 37 is prohibited.

  When the pressurizing operation of the high-pressure fuel pump 24 is stopped, the fuel pressure in the portion upstream of the check valve 36 in the high-pressure fuel pump 24 becomes the feed pressure set value Pf. The fuel pressure in the high-pressure fuel pipe 26 is maintained at a pressure higher than the feed pressure set value Pf for a while after the pressurization operation is stopped. However, at this time, since the fuel supply to the high-pressure fuel pipe 26 is stopped, the fuel pressure in the high-pressure fuel pipe 26 gradually decreases according to the fuel consumption by the fuel injection of the in-cylinder injection valve 37. When the fuel pressure in the high-pressure fuel pipe 26 becomes equal to or less than the feed pressure set value Pf, the check valve 36 is opened and fuel is introduced into the high-pressure fuel pipe 26. Therefore, the fuel pressure in the high-pressure fuel pipe 26 after the pressurization operation of the high-pressure fuel pump 24 is finally held at the feed pressure set value Pf. Therefore, even when an abnormality occurs in the fuel pressure sensor 38, the fuel pressure in the high-pressure fuel pipe 26 can be grasped.

  On the other hand, at this time, the calculation mode of the energization time of the in-cylinder injection valve 37 is switched so that the energization time is calculated using the feed pressure set value Pf instead of the fuel pressure detection value Pm. That is, the energization time during which fuel for the in-cylinder injection amount Qd can be injected is calculated in a state where the pressure of the fuel supplied to the in-cylinder injection valve 37 becomes the feed pressure set value Pf. Therefore, even when an abnormality occurs in the fuel pressure sensor 38, the in-cylinder injection valve 37 can perform fuel injection for the in-cylinder injection amount Qd.

  In this embodiment, in order to ensure diagnosis accuracy, abnormality diagnosis of the fuel pressure sensor 38 is performed over a certain period of time. In addition, it takes time until the deviation between the detected fuel pressure value Pm and the target fuel pressure Pt increases beyond the specified value α after the abnormality of the fuel pressure sensor 38 occurs. Therefore, even if an abnormality occurs in the fuel pressure sensor 38, the fail-safe process is not started immediately, and if partial lift injection that has a great influence on the injection amount accuracy is executed during that period, the fail-safe process is not performed. Combustion may worsen by the start, resulting in misfire and engine stall. In particular, in the fuel injection during the compression stroke by the partial lift injection of the in-cylinder injection valve 37 in the catalyst warm-up promotion control described above, if the injection amount deviates from the required amount, the reach of the fuel spray changes, If the injected fuel is put on the in-cylinder airflow, the injected fuel cannot be collected around the spark plug. For this reason, when the energization time for partial injection of the in-cylinder injection valve 37 is set based on the detected fuel pressure value Pm of the fuel pressure sensor 38 in which an abnormality has occurred, deterioration of combustion is particularly likely to occur.

  On the other hand, as described above, one of the abnormalities of the fuel pressure sensor 38 is a stack abnormality. When a stack abnormality occurs, the detected fuel pressure value Pm of the fuel pressure sensor 38 does not change with a constant value. In the present embodiment, even if the first abnormality determination condition is not satisfied, if the fuel pressure detection value Pm of the fuel pressure sensor 38 remains constant for a specified time T2 or longer, the partial lift injection is prohibited and the in-cylinder injection valve 37 Fuel injection is performed without performing partial lift injection. Such prohibition of partial lift injection is performed earlier than the fail-safe process is started when it is determined by the abnormality diagnosis that there is an abnormality. Therefore, it is possible to suppress the occurrence of misfire and engine stall due to the deterioration of combustion before the start of the fail-safe process.

  Incidentally, the abnormality of the fuel pressure sensor 38 determined to be abnormal in the abnormality diagnosis includes an abnormality other than a stack abnormality such as a decrease in the response speed of the fuel pressure sensor 38, for example. However, in these abnormalities, the detected fuel pressure value Pm changes to follow the fuel pressure in the high-pressure fuel pipe 26 to some extent. For this reason, in the case of an abnormality other than a stack abnormality, the combustion rarely deteriorates until a misfire or an engine stall occurs in the time required for the abnormality diagnosis.

  When an abnormality occurs in the fuel pressure sensor 38, the fuel pressure in the high-pressure fuel pipe 26 cannot be properly controlled, and the fuel pressure cannot be confirmed. Therefore, when an abnormality occurs in the fuel pressure sensor 38, the fuel pressure in the high-pressure fuel pipe 26 may be significantly lower than required. When the fuel pressure in the high-pressure fuel pipe 26 decreases, the injection pressure of fuel injection by the in-cylinder injection valve 37 also decreases, and during high load operation in which the in-cylinder pressure during injection increases, the injection pressure becomes insufficient and the in-cylinder injection valve 37 There is a risk that the fuel injection due to will be impossible. In this regard, in the present embodiment, fuel injection when partial lift injection is prohibited is performed by full lift injection of the in-cylinder injection valve 37 when the engine load factor KL is less than the specified value γ, and the engine load factor KL is specified. When the value is greater than or equal to γ, the operation is performed by the port injection valve 25. Therefore, even if the fuel pressure in the high-pressure fuel pipe 26 is low due to an abnormality in the fuel pressure sensor 38, a situation in which fuel injection becomes impossible due to a shortage of injection pressure can be avoided.

  By the way, if the detected fuel pressure value Pm deviates from the actual value due to the abnormality of the fuel pressure sensor 38, the injection amount per energization time of the in-cylinder injection valve 37 changes and a deviation of the fuel injection amount occurs. Further, as described above, when the valve body 55 of the in-cylinder injection valve 37 is opened, the fuel pressure in the fuel chamber 59 becomes a resistance. Therefore, if the fuel pressure changes, the lift start energization time T0 and the P / L maximum energization time Tpmax also change, and such a change also causes a deviation in the fuel injection amount when an abnormality occurs in the fuel pressure sensor 38. On the other hand, in the multi-stage injection in which the fuel for the required injection amount Qt is divided and injected into a plurality of times, the valve element 55 is opened a plurality of times. Therefore, the influence of the changes in the lift start energization time T0 and the P / L maximum energization time Tpmax caused by the deviation of the fuel pressure detection value Pm on the injection amount accuracy of the in-cylinder injection valve 37 is determined by the amount of fuel required for the injection amount Qt. Compared to the case of injection with one fuel injection, the multi-stage injection is larger. On the other hand, in the engine control apparatus of the present embodiment, multistage injection is prohibited when the abnormality of the fuel pressure sensor 38 is suspected. Therefore, the deterioration of combustion when an abnormality actually occurs in the fuel pressure sensor 38 is further suppressed.

  By the way, during the fail-safe process, the fuel injection control of the in-cylinder injection valve 37 is performed on the assumption that the fuel pressure in the high-pressure fuel pipe 26 is the feed pressure set value Pf. However, during the fail-safe process, even if the fuel pressure in the high-pressure fuel pipe 26 deviates from the feed pressure set value Pf, it cannot be confirmed directly. Therefore, there is a risk in performing partial lift injection during fail-safe processing, which has a great influence on fuel injection accuracy and combustion pressure. In addition, during the fail safe process, the fuel injection pressure by the in-cylinder injection valve 37 is low, so that the intended purpose of partial lift injection such as an increase in the fuel concentration around the spark plug during the catalyst warm-up promotion control is achieved. become unable. Therefore, in the present embodiment, partial lift injection is prohibited even during fail-safe processing.

  Further, during the fail-safe process, the fuel injection pressure by the in-cylinder injection valve 37 is low, and during high load operation in which the in-cylinder pressure increases, the in-cylinder injection valve 37 is appropriately operated due to insufficient injection pressure. It may become impossible to inject fuel. Therefore, in the present embodiment, fuel injection during fail-safe processing in which partial lift injection is prohibited is also performed when in-cylinder injection is performed when the engine load factor KL is less than the specified value γ, as in the case of prohibiting partial lift injection during abnormality diagnosis. This is performed by full lift injection of the valve 37, and is performed by the port injection valve 25 when the engine load factor KL is equal to or greater than a specified value γ.

  By the way, if the engine stall occurs before the diagnosis result is confirmed, the diagnosis will be terminated halfway, so the driver will not be notified by lighting the indicator and the history will not be recorded in the non-volatile memory. It will be. Therefore, in such a case, it is delayed for the driver to notice the abnormality, or it becomes difficult to identify the abnormal part at the time of repair. In this respect, in the present embodiment, the occurrence of engine stall due to combustion deterioration during diagnosis can be suppressed, so that notification and history recording when an abnormality occurs can be performed more reliably.

  In this embodiment, the high-pressure fuel pump 24 corresponds to a “fuel pump” for supplying fuel to the fuel injection valve, and the in-cylinder injection valve 37 is a “fuel injection valve” for supplying fuel from the fuel pump. It is the composition equivalent to. In the present embodiment, the electronic control unit 40 has a configuration corresponding to a “fuel pressure control unit”, “injection control unit”, “diagnosis unit”, and “air-fuel ratio control unit”.

According to the engine control apparatus of the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, even if the first abnormality determination condition that is satisfied when the abnormality occurs in the fuel pressure sensor 38, the second abnormality determination condition that is satisfied when there is a possibility of abnormality in the fuel pressure sensor 38 is When it is established, the injection control of the in-cylinder injection valve 37 and the port injection valve 25 is performed so that fuel injection is performed without performing partial lift injection. The second abnormality determination condition is set to a condition that is established before the first abnormality determination condition when an abnormality occurs in the fuel pressure sensor 38. Therefore, deterioration of combustion of the engine 10 being diagnosed can be suppressed while ensuring diagnosis accuracy of abnormality of the fuel pressure sensor 38.

  (2) Since the diagnosis is prevented from being terminated in the middle due to the occurrence of an engine stall, when an abnormality occurs, notification of the occurrence and recording of the occurrence history can be performed more reliably.

  (3) In the present embodiment, the first abnormality is established so that the state where the deviation between the fuel pressure detection value Pm of the fuel pressure sensor 38 and the target fuel pressure Pt is equal to or greater than the specified value α continues for the specified abnormality determination time T1 or longer. Determination conditions are set, and abnormality diagnosis of the fuel pressure sensor 38 is performed. In order to perform such abnormality diagnosis with high accuracy, it is necessary to set a certain long time as the abnormality determination time T1. On the other hand, as described above, in the present embodiment, it is possible to suppress deterioration of combustion when partial lift injection is executed during a period from occurrence of abnormality until diagnosis is confirmed. Therefore, it is possible to set a longer time for the abnormality determination time T1, and the diagnostic accuracy can be improved.

  (4) In the present embodiment, the second abnormality determination condition is set so as to be satisfied when the state where the fuel pressure detection value Pm is constant continues for a specified time T2 or more. Therefore, when the stack abnormality of the fuel pressure sensor 38 occurs, it is possible to suppress the deterioration of combustion during the period until the diagnosis result is confirmed.

  (5) In this embodiment, the catalyst that performs multi-stage injection of fuel injection during the intake stroke by full lift injection and fuel injection during the compression stroke by partial lift injection during the idling operation of the engine 10 while the catalyst device 19 is warming up. Warm-up acceleration control is performed. In such catalyst warm-up promotion control, the partial lift injection during the compression stroke ensures the combustibility at the cold start when the combustion is difficult to stabilize. For this reason, if a deviation occurs in the injection amount of the partial lift injection in the catalyst warm-up promotion control, serious combustion deterioration is likely to occur, and misfire or engine stall is likely to occur. In this regard, in the present embodiment, partial lift injection is prohibited when the second abnormality determination condition is satisfied and the abnormality of the fuel pressure sensor 38 is suspected, so that the fuel pressure sensor is controlled during catalyst warm-up promotion control. Even if 38 abnormalities occur, it is difficult to cause misfire or engine stall.

  (6) In the present embodiment, fuel injection when partial lift injection is prohibited is performed by in-cylinder injection of the in-cylinder injection valve 37 by full lift injection when the engine load factor KL is less than the specified value γ, and the engine load factor KL Is equal to or greater than the specified value γ, the port injection of the port injection valve 25 is performed. For this reason, even when the fuel pressure in the high-pressure fuel pipe 26 is reduced due to an abnormality in the fuel pressure sensor 38, it is possible to prevent the fuel injection from being disabled due to a shortage of the injection pressure.

  (7) In the present embodiment, when the second abnormality determination condition is satisfied, multi-stage injection in which fuel for the required injection amount Qt is divided and injected multiple times is prohibited. Therefore, deterioration of combustion when an abnormality has actually occurred in the fuel pressure sensor 38 is more suitably suppressed.

(Second Embodiment)
Next, a second embodiment of the engine control device will be described in detail with reference to FIG. In the present embodiment and the third embodiment to be described later, the components common to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In addition, the engine control apparatus of this embodiment changes the content of the 2nd abnormality determination conditions used as the conditions of partial lift injection prohibition in the P / L injection prohibition determination routine in the engine control apparatus of 1st Embodiment. The parts other than the processing contents of the routine are the same as those in the first embodiment.

  This embodiment is premised on the implementation of air-fuel ratio feedback control. The air-fuel ratio feedback control is a control in which the air-fuel ratio of the air-fuel mixture burned by the engine 10 is set as the target air-fuel ratio. The electronic control unit 40 performs requested injection so that the air-fuel ratio of the air-fuel mixture combusted in the engine 10 becomes approximately the target air-fuel ratio based on the current cylinder inflow air amount ascertained from the engine speed NE and the engine load factor KL. The amount is calculated. However, with only such open control of the required injection amount, there is a slight difference between the actual air-fuel ratio and the target air-fuel ratio due to individual differences in the intake characteristics and injection characteristics of the engine 10. Therefore, in the air-fuel ratio feedback control, the air-fuel ratio is controlled to the target air-fuel ratio by performing feedback correction of the required injection amount in accordance with the deviation between the air-fuel ratio detected value by the air-fuel ratio sensor 18 and the target air-fuel ratio.

  Such air-fuel ratio feedback control is performed by the electronic control unit 40. That is, in this embodiment, the electronic control unit 40 corresponds to an air-fuel ratio control unit that corrects the required injection amount so that the detected value of the air-fuel ratio becomes the target air-fuel ratio based on the detected value of the air-fuel ratio sensor 18. It has become.

  FIG. 7 shows a flowchart of a P / L injection prohibition determination routine applied to this embodiment. The processing of this routine is repeatedly executed at regular control intervals by the electronic control unit 40 during engine operation.

  When the processing of this routine is started, it is first determined in step S200 whether or not the abnormality flag is cleared. If the abnormality flag is set (NO), the process proceeds to step S210. After the partial lift injection is prohibited in step S210, the process of this routine is terminated.

  On the other hand, if the abnormality flag is cleared (S200: YES), the process proceeds to step S202. In step S202, the absolute value of the air-fuel ratio feedback (F / B) correction amount is equal to or greater than the prescribed determination value β. It is determined whether or not there is. The air-fuel ratio feedback correction amount is a correction amount of the required injection amount that is performed in accordance with the deviation between the air-fuel ratio detected value by the air-fuel ratio sensor 18 and the target air-fuel ratio in the air-fuel ratio feedback control described above.

  Here, if the absolute value of the air-fuel ratio feedback correction amount is greater than or equal to the determination value β (YES), the process proceeds to step S210 and the partial lift injection is prohibited, and then the process of this routine is terminated. The On the other hand, if the absolute value of the air-fuel ratio feedback correction amount is less than the determination value β (NO), the process proceeds to step S211, and after the partial lift injection is permitted, the process of this routine is terminated.

Next, the operation of the engine control apparatus of this embodiment will be described.
As described above, when an abnormality occurs in the fuel pressure sensor 38, the electronic control unit 40 cannot grasp the fuel pressure in the high-pressure fuel pipe 26, and hence the fuel injection pressure by the cylinder injection valve 37, and the cylinder injection valve. 37 and the actual injection amount by the in-cylinder injection valve 37 deviate from each other. On the other hand, as described above, even before correction by air-fuel ratio feedback control, the required injection amount is set to such a value that the air-fuel ratio becomes substantially the target air-fuel ratio. Since the injection amount thus deviated from the actual injection amount, the absolute value of the air-fuel ratio feedback correction amount increases. Therefore, when the absolute value of the air-fuel ratio feedback correction amount is larger than the normal range, it is suspected that the fuel pressure sensor 38 is abnormal. In this embodiment, since partial lift injection is prohibited in such a case, even if an abnormality of the fuel pressure sensor 38 has actually occurred, deterioration of combustion during diagnosis can be suppressed. Also according to this embodiment, the effects described in (1) to (3), (5), and (6) can be achieved. In this embodiment, the second abnormality determination is performed so as to be established when the absolute value of the air-fuel ratio feedback correction amount, which is the correction amount of the required injection amount by the air-fuel ratio control unit, is equal to or greater than a specified value. The condition is set.

(Third embodiment)
Next, a second embodiment of the engine control device will be described in detail with reference to FIG. Similarly to the second embodiment, the engine control device of the present embodiment also includes the contents of the second abnormality determination condition that is a partial lift injection prohibition condition in the P / L injection prohibition determination routine in the engine control device of the first embodiment. The parts other than the processing contents of the routine are the same as those in the first embodiment.

  FIG. 8 shows a flowchart of a P / L injection prohibition determination routine applied to this embodiment. The processing of this routine is repeatedly executed at regular control intervals by the electronic control unit 40 during engine operation.

  When the processing of this routine is started, it is first determined in step S200 whether or not the abnormality flag is cleared. If the abnormality flag is set (NO), the process proceeds to step S210. After the partial lift injection is prohibited in step S210, the process of this routine is terminated.

  On the other hand, if the abnormality flag is cleared (S200: YES), the process proceeds to step S203, and it is determined in step S203 whether the engine restart flag is set. The engine restart flag is a flag that is set when the current engine start is a restart after an engine stall, and is cleared when the engine 10 is normally stopped. If the engine restart flag is set (YES), the process proceeds to step S210 to prohibit partial lift injection, and then the process of this routine is terminated. On the other hand, if the engine restart flag is cleared (NO), the process proceeds to step S211, and after the partial lift injection is permitted, the process of this routine is terminated.

  Next, the operation and effect of the engine control apparatus of this embodiment will be described. As described above, when an abnormality occurs in the fuel pressure sensor 38, the injection amount of the in-cylinder injection valve 37 cannot be properly controlled, and the combustion deteriorates. Therefore, when an abnormality occurs in the fuel pressure sensor 38, engine stall is likely to occur. Therefore, when the engine stall occurs, there is a possibility that the fuel pressure sensor 38 is abnormal. In this embodiment, when the engine is restarted after the engine stalls, partial lift injection is prohibited. Therefore, even when an abnormality occurs in the fuel pressure sensor 38, deterioration of combustion during diagnosis can be suppressed, and reoccurrence of engine stall until the diagnosis is confirmed and failsafe processing is started is suppressed. be able to. Also according to this embodiment, the effects described in (1) to (3), (5), and (6) can be achieved. In this embodiment, the second abnormality determination condition is set so as to be satisfied when an engine stall occurs.

  Incidentally, if the combustion is greatly deteriorated due to an abnormality of the fuel pressure sensor 38, an engine stall may occur immediately after the engine 10 is started. In such a case, the abnormality diagnosis of the fuel pressure sensor 38 cannot be performed to the end while the engine 10 is operating, and the engine stall may be repeated without the abnormality diagnosis being confirmed. In this regard, in the present embodiment, partial lift injection is prohibited when an engine stall occurs, and combustion deterioration of the engine 10 before the determination of the abnormality diagnosis result at the time of abnormality of the fuel pressure sensor 38 is suppressed. Therefore, even when the combustion of the engine 10 deteriorates until an engine stall occurs due to an abnormality of the fuel pressure sensor 38, the abnormality can be easily diagnosed.

In addition, the said embodiment can also be changed and implemented as follows.
In the first embodiment, when the state where the detected value of the fuel pressure is constant continues for the specified time T2 or more, the second abnormality determination condition is satisfied and the partial lift injection is prohibited. Since the second abnormality determination condition only needs to be satisfied when there is a possibility of abnormality of the fuel pressure sensor 38, the specified time T2 is set to a relatively short time that does not lead to the determination of the stack abnormality. When such a state in which the detected value of the fuel pressure is constant exceeds the specified time T2 and further continues, the stack abnormality becomes definite. Therefore, a time longer than the specified time T2 is set as the stack abnormality determination time, and the first abnormality determination condition is set so as to be satisfied when the fuel pressure detection value continues for the same stack abnormality determination time. Thus, it is possible to diagnose a stack abnormality of the fuel pressure sensor 38. Furthermore, when the state where the deviation between the fuel pressure detection value Pm and the target fuel pressure Pt is equal to or greater than the specified value continues for the specified abnormality determination time T1 or longer, the state where the fuel pressure detection value is constant continues for the same stack abnormality determination time. Alternatively, the first abnormality determination condition may be set so as to hold.

  In the above embodiment, the mode of fuel injection when partial lift injection is prohibited is switched according to the engine load factor KL. However, such switching may not be performed. For example, when partial lift injection is prohibited, fuel injection is always performed only by port injection, or by adding the partial lift injection to full lift injection without changing the split ratio between in-cylinder injection and port injection. Or may be performed.

  In the above embodiment, as a fail-safe process that is executed when the first abnormality determination condition is satisfied and it is determined that the fuel pressure sensor 38 is abnormal, the pressurization operation of the high-pressure fuel pump 24 and the in-cylinder injection valve are The calculation mode of the energization time 37 is switched. Such fail-safe processing may be performed in another manner.

  In the above embodiment, all the multistage injections are prohibited when the second abnormality determination condition is satisfied. As described above, in the full lift injection, the influence of the abnormality of the fuel pressure sensor 38 on the combustion of the engine 10 is smaller than in the partial lift injection. Therefore, even if there is a situation in which misfire or engine stall occurs if multistage injection including partial lift injection is performed, the combustion of the engine 10 is within a range that does not lead to the occurrence of misfire or engine stall in multistage injection using only full lift injection. Deterioration may remain. In such a case, when the second abnormality determination condition is satisfied, not all the multistage injections but only the multistage injection including the partial lift injection may be prohibited and the multistage injection only by the full lift injection may be permitted.

  In each of the above embodiments, (i) when the fuel pressure detection value Pm continues for a specified time T2 in a constant state, (b) when the absolute value of the air-fuel ratio feedback correction amount is equal to or greater than the specified value γ, 2) When the engine stall occurs, the second abnormality determination condition is set so as to be satisfied in each case. For the two cases (i) to (ha), the second abnormality determination condition is set so as to hold in either case, or in any case of the three cases (ii) to (ha) The second abnormality determination condition may be set so as to be established. Furthermore, if the fuel pressure sensor 38 is set so as to be satisfied before the first abnormality determination condition is established when there is a possibility of abnormality of the fuel pressure sensor 38 and the abnormality of the fuel pressure sensor 38 occurs, the above (ii) to (i). The second abnormality determination condition may be set so as to be satisfied in cases other than (ha) or to be satisfied also in cases other than the above (ii) to (ha).

  In the above embodiment, the first abnormality determination condition is set so as to be satisfied when the state where the deviation between the fuel pressure detection value Pm and the target fuel pressure Pt is equal to or greater than the specified value α continues for the abnormality determination time T1 or more. As long as the first abnormality determination condition is a condition that is satisfied when an abnormality occurs in the fuel pressure sensor 38, other conditions may be used.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake passage, 15 ... Intake port, 16 ... Cylinder, 17 ... Exhaust passage, 18 ... Air-fuel ratio sensor, 19 ... Catalyst apparatus, 20 ... Fuel tank, 21 ... Feed pump, 22 ... Low pressure fuel passage, DESCRIPTION OF SYMBOLS 23 ... Low pressure fuel piping, 24 ... High pressure fuel pump (fuel pump), 25 ... Port injection valve, 26 ... High pressure fuel piping, 37 ... In-cylinder injection valve (fuel injection valve: 55 ... Valve body), 38 ... Fuel pressure sensor, 40: Electronic control unit (fuel pressure control unit, injection control unit, diagnostic unit, air-fuel ratio control unit).

Claims (10)

A fuel injection valve that injects fuel by opening a valve body in response to energization, a fuel pump that supplies fuel to the fuel injection valve, and a pressure of fuel that is supplied from the fuel pump to the fuel injection valve Applied to an engine equipped with a fuel pressure sensor for detecting a certain fuel pressure, and sets the energization time of the fuel injection valve based on a required injection amount set according to an engine operating state and a detected value of the fuel pressure. Injection that performs injection control of the fuel injection valve by partial lift injection that stops injection before the valve body opens to the fully open position and full lift injection that stops injection after the valve body opens to the fully open position An engine control device comprising a control unit,
A first abnormality determination condition that is established when an abnormality occurs in the fuel pressure sensor;
A condition that is established when there is a possibility of abnormality of the fuel pressure sensor, and a second abnormality determination condition that is established before the first abnormality determination condition when the abnormality of the fuel pressure sensor occurs, is set,
A diagnostic unit for determining a temporary abnormality of the fuel pressure sensor when the second abnormality determination condition is satisfied, and determining an abnormality of the fuel pressure sensor when the first abnormality determination condition is satisfied;
The injection control unit performs injection control of the fuel injection valve so as to perform fuel injection without performing partial lift injection when the diagnosis unit determines a temporary abnormality of the fuel pressure sensor. Engine control device. The fuel pump is a high-pressure fuel pump that pressurizes fuel pumped from a fuel tank by a feed pump,
The engine control device controls the operation of the high-pressure fuel pump based on the detected value of the fuel pressure by the fuel pressure sensor so that the detected value of the fuel pressure becomes a target fuel pressure set according to the engine operating state. Comprising a part,
The fuel pressure control unit stops the pressurizing operation of the high-pressure fuel pump when the diagnosis unit determines that the fuel pressure sensor is abnormal,
When the diagnosis unit determines that the fuel pressure sensor is abnormal, the injection control unit sets the energization time of the fuel injection valve using a set value of the feed pressure of the feed pump instead of the detected value of the fuel pressure The engine control device according to claim 1. The first abnormality determination condition is set so as to be established when a state where a deviation between the detected value of the fuel pressure and the target fuel pressure is a specified value or more continues for a specified abnormality determination time or longer. Engine control device. The engine control device according to any one of claims 1 to 3, wherein the second abnormality determination condition is set so as to be established when a state in which the detected value of the fuel pressure is constant continues for a specified time or longer. Set a time longer than the specified time as the stack abnormality determination time,
The engine control apparatus according to claim 4, wherein the first abnormality determination condition is set such that the state where the detected value of the fuel pressure is constant is satisfied when the stack abnormality determination time continues. The engine control device according to any one of claims 1 to 5, wherein the second abnormality determination condition is satisfied so as to be satisfied when an engine stall occurs. An air-fuel ratio control unit that corrects the required injection amount based on a detected value of an air-fuel ratio sensor that detects an air-fuel ratio of the air-fuel ratio burned by the engine so that the detected value of the air-fuel ratio becomes a target air-fuel ratio; ,
The second abnormality determination condition is set so as to be established when an absolute value of a correction amount of the required injection amount by the air-fuel ratio control unit is equal to or greater than a specified value. The engine control device according to item. The said injection control part prohibits the multistage injection which divides | segments the fuel for required injection quantity into multiple times, and injects, when the said 2nd abnormality determination condition is satisfied. Engine control device. The injection control unit performs multi-stage injection of fuel injection during an intake stroke by full lift injection and fuel injection during a compression stroke by partial lift injection during idle operation of an engine during warm-up of a catalyst device that purifies exhaust gas. Item 9. The engine control device according to any one of Items 1 to 8. The fuel pump is a high-pressure fuel pump that pressurizes fuel pumped from a fuel tank by a feed pump,
The engine includes, as the fuel injection valve, an in-cylinder injection valve that injects fuel supplied from the high-pressure fuel pump into a cylinder, and fuel supplied from the feed pump without passing through the high-pressure fuel pump. It has a port injection valve that injects into the intake port,
When the partial lift injection is prohibited, the injection control unit performs fuel injection by the port injection valve when the engine load factor is equal to or greater than a specified value, and when the engine load factor is less than the specified value, the in-cylinder injection is performed. The engine control device according to any one of claims 1 to 9, wherein fuel injection is performed by full lift injection of a valve.

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