JP2011256726A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately suppress deviation of an air fuel ratio of a mixed gas from a target air fuel ratio caused by the time delay in a fuel pressure change in a high-pressure fuel passage.SOLUTION: An internal combustion engine 7 includes a high-pressure fuel injection valve 47 directly injecting a fuel into a cylinder, a low-pressure fuel injection valve 37 injecting the fuel into the intake port 72 of the cylinder, and a high-pressure fuel pump 5 adjusting the fuel pressure in a high-pressure delivery pipe 46 in accordance with an engine operation state. An electronic control device 8 adjusts the fuel pressure in the high-pressure delivery pipe 46 by the high-pressure fuel pump 5 in accordance with an engine load, and also sets the basic proportion of the fuel injection amount of the high-pressure fuel injection valve 47 in the total fuel injection amount which is the total sum of the fuel injection amount of each injection valve 47, 37, in accordance with an engine rotation speed and an engine load. When the fuel pressure during a low-load operation is equal to or higher than a predetermined pressure that is higher than a fuel pressure which is made to correspond to a case when the engine is operated at a low load, the controller corrects the proportion of the fuel injection amount of the high-pressure fuel injection valve 47 to be larger than the basic proportion.

Description

  The present invention relates to a high-pressure fuel injection valve that directly injects fuel in a high-pressure fuel passage into a cylinder, a low-pressure fuel injection valve that injects fuel in a low-pressure fuel injection passage to an intake port of the cylinder, and an engine operating state And a control mechanism for adjusting the fuel pressure in the high-pressure fuel passage according to the control mechanism.

  Conventionally, as a control device of this type of internal combustion engine, for example, there is one described in Patent Document 1. In conventional control apparatuses for internal combustion engines, including those described in Patent Document 1, fuel in the high-pressure fuel passage is directly injected into the cylinder from the high-pressure fuel injection valve, and fuel in the low-pressure fuel passage is low-pressure fuel. Injection is supplied from the injection valve to the intake port of the cylinder. Here, the high-pressure fuel passage is provided with a high-pressure fuel pump, and the fuel pressure in the high-pressure fuel passage is adjusted according to the engine load by controlling the discharge mode of the fuel from the high-pressure fuel pump. It has become. Specifically, in order to enable fuel injection from the high pressure fuel injection valve against the pressure in the combustion chamber that becomes high pressure, it is lower when the engine speed is high and lower when the engine load is high. The fuel pressure is increased compared to sometimes.

  Further, in such a control device, the total amount of fuel injected from both the high pressure fuel injection valve and the low pressure fuel injection valve is calculated according to the engine operating state, and is injected from the high pressure fuel injection valve at the calculated total. The fuel amount ratio is set according to the engine operating state, for example, the engine speed and the engine load. As a result, the fuel consumption of the internal combustion engine is reduced and the torque fluctuation of the engine is reduced.

  By the way, fuel injection by the high pressure fuel injection valve is performed by displacing the valve body by energizing the injection valve. Further, in order to open the high pressure fuel injection valve, it is necessary to apply a force for displacing the valve body in the valve opening direction against the fuel pressure acting in the valve closing direction on the valve body. . For this reason, when the energization time for the high-pressure fuel injection valve is set to be excessively short, fuel injection may not be suitably performed. Therefore, the lower limit value of the energization time for the high pressure fuel injection valve is set larger as the fuel pressure in the high pressure fuel passage is higher.

JP 2009-24517 A

  By the way, in the case of adjusting the fuel pressure in the high-pressure fuel passage according to the engine load, the following problems may occur when shifting from the high load operation to the low load operation. That is, when the fuel pressure in the high-pressure fuel passage is increased during high-load operation and the operation is shifted to low-load operation, the high-pressure fuel pump is controlled to lower the fuel pressure in the high-pressure fuel passage. . However, because there is a time delay for the actual fuel pressure to drop to the pressure corresponding to the low load operation, the fuel pressure will be lower than the pressure corresponding to the low load operation for a while after shifting to the low load operation. Become high. As a result, there is a possibility that the air-fuel ratio of the air-fuel mixture becomes richer than the target air-fuel ratio and the exhaust properties deteriorate.

  In recent years, for example, for the purpose of improving exhaust properties, a device has been developed to increase the maximum value of the fuel pressure in the high pressure fuel passage in order to further increase the fuel pressure injected from the high pressure fuel injection valve during high load operation. Has been done. However, the time required for the actual fuel pressure to drop to the fuel pressure corresponding to the low load operation when shifting from the high load operation to the low load operation becomes longer as the fuel pressure in the high load operation is increased. As a result, the above-described problem becomes more remarkable.

  In contrast, in order to reduce the amount of fuel injected from the high pressure fuel injection valve after shifting to low load operation, the opening time of the high pressure fuel injection valve is shortened, that is, the energization time for the high pressure fuel injection valve is shortened. It is possible. However, as described above, when the fuel pressure in the high pressure fuel passage is high, the lower limit value of the energization time for the high pressure fuel injection valve is set accordingly, so the energization time is shortened and the high pressure fuel injection valve is There is a limit to reducing the amount of fuel injected.

  In addition, in order to reduce the fuel pressure in the high-pressure delivery pipe 46, a high-pressure fuel pump with a leak mechanism for leaking fuel has been developed. There are limits to doing it.

  Such problems are not limited to those that occur when shifting from high-load operation to low-load operation, but can also occur when shifting from low-load operation to high-load operation. Further, the fuel pressure is not limited to the one that adjusts according to the engine load, but the one that adjusts the fuel pressure according to the engine operation state is generally common.

  The present invention has been made in view of such circumstances, and its purpose is to accurately determine that the air-fuel ratio of the air-fuel mixture deviates from the target air-fuel ratio due to the time delay of the fuel pressure change in the high-pressure fuel passage. An object of the present invention is to provide a control device for an internal combustion engine that can be suppressed.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention described in claim 1 is a high pressure fuel injection valve that directly injects fuel in a high pressure fuel passage into a cylinder, and a low pressure that injects fuel in a low pressure fuel injection passage to an intake port of the cylinder. The fuel injection valve is applied to an internal combustion engine including a fuel injection valve and an adjustment mechanism that adjusts the fuel pressure in the high pressure fuel passage according to the engine operating state, and is injected from both the high pressure fuel injection valve and the low pressure fuel injection valve. A control device for an internal combustion engine that sets a ratio of a fuel amount injected from the high-pressure fuel injection valve in a total fuel injection amount that is a sum of fuel amounts to be determined according to an engine operating state, the fuel in the high-pressure fuel passage When the pressure is higher than the pressure corresponding to the engine operating state, the ratio of the fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount compared to the case where the pressure is equal to or lower than the pressure corresponding to the engine operating state And as its gist to increase.

  According to this configuration, when the fuel pressure in the high-pressure fuel passage shifts from the high state to the engine operating state where low fuel pressure is required, the fuel pressure is higher than the pressure corresponding to the engine operating state. It is injected from the high pressure fuel injection valve in the total fuel injection amount, which is the sum of the fuel amounts injected from both the high pressure fuel injection valve and the low pressure fuel injection valve, compared to the case where the pressure is equal to or lower than the pressure corresponding to the engine operating state. The proportion of fuel is increased. As a result, the fuel pressure in the high-pressure fuel passage is actively consumed as compared with the conventional control configuration in which such a ratio change is not performed, so that the fuel pressure in the passage can be quickly reduced. Due to the fact that the pressure is higher than the pressure corresponding to the engine operating state, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be shortened. Accordingly, it is possible to accurately suppress the deviation of the air-fuel ratio of the air-fuel mixture from the target air-fuel ratio due to the time delay of the fuel pressure change in the high-pressure fuel passage.

  Incidentally, there is a concern that problems such as an increase in fuel consumption of the internal combustion engine and an increase in torque fluctuation are caused by increasing the ratio of the amount of fuel injected from the high-pressure fuel injection valve. Therefore, it is desirable to increase the ratio of the amount of fuel injected from the high-pressure fuel injection valve within a range in which such increase in fuel consumption and torque fluctuation are allowed.

  (2) According to the invention described in claim 1, according to the invention described in claim 2, the ratio of the fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount is determined according to the engine operating state. When the fuel pressure in the setting unit to be set and the high-pressure fuel passage is higher than the pressure corresponding to the engine operating state, the ratio of the fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount is A correction unit that corrects larger than the ratio set by the setting unit, and when the fuel pressure in the high-pressure fuel passage is equal to or lower than the pressure corresponding to the engine operating state, the ratio set by the setting unit When the fuel pressure in the high pressure fuel passage is higher than the pressure corresponding to the engine operating state, the correction unit corrects the fuel. The It said at a rate high-pressure fuel injection valves and the injection of fuel from said low-pressure fuel injection valve can be embodied with aspects such as performed.

  When the fuel pressure in the high pressure fuel passage is higher than the pressure corresponding to the engine operating state, and the ratio of the fuel amount injected from the low pressure fuel injection valve is set to “0” by the setting unit. The ratio of the amount of fuel injected from the high-pressure fuel injection valve may be set to “0” with the ratio set by the setting unit without performing correction by the correction unit.

  (3) According to a second aspect of the present invention, as set forth in the third aspect of the present invention, the setting unit calculates a ratio of a fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount, The present invention can be embodied in such a manner that it is set according to the engine speed and the engine load.

  (4) The invention according to claim 4 is the control device for an internal combustion engine according to claim 2 or 3, wherein the fuel pressure in the high pressure fuel passage is adjusted by the adjusting mechanism in accordance with the engine load. And when the fuel pressure in the high pressure fuel passage is not less than a predetermined pressure higher than the fuel pressure corresponding to the low load operation during the low load operation of the internal combustion engine, The gist of the invention is to correct the ratio of the injected fuel amount to be larger than the ratio set by the setting unit.

  In the case of adjusting the fuel pressure in the high-pressure fuel passage according to the engine load by the adjusting mechanism, the fuel pressure is increased as the engine load is higher. In such a control configuration, when the fuel pressure in the high-pressure fuel passage is increased during high-load operation, when shifting to a low-load operation, an adjustment mechanism is provided to lower the fuel pressure in the high-pressure fuel passage accordingly. Is controlled. However, because there is a time delay for the actual fuel pressure to drop to the pressure corresponding to the low load operation, the fuel pressure will be lower than the pressure corresponding to the low load operation for a while after shifting to the low load operation. Become high. At this time, according to the above configuration, the ratio of the amount of fuel injected from the high pressure fuel injection valve is set assuming that the fuel pressure in the high pressure fuel passage is equal to or higher than a predetermined pressure higher than the fuel pressure corresponding to the low load operation. The ratio set by the section, that is, the ratio set in accordance with the engine operating state is made larger. As a result, by actively consuming the fuel in the high-pressure fuel passage, the fuel pressure in the passage can be quickly reduced, and the fuel pressure is higher than the pressure corresponding to the low load operation. Thus, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be shortened. Accordingly, it is possible to accurately suppress the deviation of the air-fuel ratio of the air-fuel mixture from the target air-fuel ratio due to the time delay of the fuel pressure drop in the high-pressure fuel passage.

  (5) The invention according to claim 5 is the control apparatus for an internal combustion engine according to any one of claims 2 to 4, wherein the correction unit includes the high-pressure fuel injection valve and the low-pressure fuel injection valve. The total fuel injection amount, which is the sum of the fuel amounts injected from both, is the sum of the lower limit value of the fuel amount injected from the high pressure fuel injection valve and the lower limit value of the fuel amount injected from the low pressure fuel injection valve If it is smaller than that, the gist is to prohibit the fuel injection from the low pressure fuel injection valve and inject the total fuel injection amount from the high pressure fuel injection valve.

  According to this configuration, the total fuel injection amount, which is the sum of the fuel amounts injected from both the high pressure fuel injection valve and the low pressure fuel injection valve, through the correction unit is the lower limit value of the fuel amount injected from the high pressure fuel injection valve. And the lower limit value of the fuel amount injected from the low pressure fuel injection valve, the total fuel injection amount is injected by the high pressure fuel injection valve. As a result, the fuel pressure in the high-pressure fuel passage is more actively consumed, so that the fuel pressure in the passage can be reduced more quickly, and the fuel pressure is higher than the pressure corresponding to the engine operating state. As a result, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be further shortened.

  (6) The invention according to claim 6 is the control apparatus for an internal combustion engine according to any one of claims 2 to 5, wherein the correction unit includes the high-pressure fuel injection valve and the low-pressure fuel injection valve. The total fuel injection amount, which is the sum of the fuel amounts injected from both, is the sum of the lower limit value of the fuel amount injected from the high pressure fuel injection valve and the lower limit value of the fuel amount injected from the low pressure fuel injection valve In the case of the above, the gist is to correct the ratio of the fuel amount injected from the high-pressure fuel injection valve so as to be the maximum value of the fuel amount that can be injected from the high-pressure fuel injection valve at that time. .

  According to this configuration, the total fuel injection amount, which is the sum of the fuel amounts injected from both the high pressure fuel injection valve and the low pressure fuel injection valve, through the correction unit is the lower limit value of the fuel amount injected from the high pressure fuel injection valve. And the lower limit value of the amount of fuel injected from the low pressure fuel injection valve is greater than or equal to the maximum amount of fuel that can be injected at that time. As a result, the fuel pressure in the high-pressure fuel passage is more actively consumed, so that the fuel pressure in the passage can be reduced more quickly, and the fuel pressure is higher than the pressure corresponding to the engine operating state. As a result, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be further shortened.

  (7) The invention according to claim 7 is a high-pressure fuel injection valve that directly injects fuel in the high-pressure fuel passage into the cylinder, and a low-pressure that injects fuel in the low-pressure fuel injection passage to the intake port of the cylinder. The fuel injection valve is applied to an internal combustion engine including a fuel injection valve and an adjustment mechanism that adjusts the fuel pressure in the high pressure fuel passage according to the engine operating state, and is injected from both the high pressure fuel injection valve and the low pressure fuel injection valve. A control device for an internal combustion engine that sets a ratio of a fuel amount injected from the high-pressure fuel injection valve in a total fuel injection amount that is a sum of fuel amounts to be determined according to an engine operating state, the fuel in the high-pressure fuel passage When the pressure is lower than the pressure corresponding to the engine operation state, the ratio of the amount of fuel injected from the high-pressure fuel injection valve in the total fuel injection valve compared to the case where the pressure is equal to or higher than the pressure corresponding to the engine operation state And as its gist to small.

  According to this configuration, when the fuel pressure in the high-pressure fuel passage shifts from a high state to an engine operating state where low fuel pressure is required, the fuel pressure is lower than the pressure corresponding to the engine operating state. It is injected from the high-pressure fuel injection valve in the total fuel injection amount, which is the sum of the fuel amounts injected from both the high-pressure fuel injection valve and the low-pressure fuel injection valve, compared to the case where the pressure is higher than the pressure corresponding to the engine operating state. The ratio of the fuel amount is reduced. As a result, the fuel pressure in the passage can be increased early by positively suppressing the consumption of fuel in the high-pressure fuel passage as compared with the conventional control configuration in which such a ratio is not changed. The period during which the air-fuel ratio of the air-fuel mixture is leaner than the target air-fuel ratio due to the fuel pressure being lower than the pressure corresponding to the engine operating state can be shortened. Accordingly, it is possible to accurately suppress the deviation of the air-fuel ratio of the air-fuel mixture from the target air-fuel ratio due to the time delay of the fuel pressure change in the high-pressure fuel passage.

  Incidentally, there is a concern that problems such as an increase in fuel consumption of the internal combustion engine and an increase in torque fluctuation are caused by reducing the ratio of the amount of fuel injected from the high-pressure fuel injection valve. Therefore, it is desirable to reduce the ratio of the amount of fuel injected from the high pressure fuel injection valve within a range in which such an increase in fuel consumption and an increase in torque fluctuation are allowed.

  (8) According to the invention described in any one of claims 1 to 7, according to the invention described in claim 8, the adjustment mechanism is provided in the high-pressure fuel passage and pumps fuel into the passage. It can be embodied with an aspect such as a high-pressure fuel pump.

The schematic diagram which shows typically the schematic structure about the control apparatus of the internal combustion engine which concerns on this invention. The map which prescribed | regulated the relationship between the engine rotational speed and engine load in the same embodiment, and the target value of the fuel pressure in a high pressure delivery pipe. The map which showed typically the relationship between the engine rotational speed and engine load in the same embodiment, and the high pressure basic ratio which is a ratio of the fuel quantity injected from the high pressure fuel injection valve in the total fuel injection quantity. The map which showed typically the relationship between the fuel pressure in the high pressure delivery pipe in the same embodiment, and the lower limit of the fuel injection amount of a high pressure fuel injection valve. The flowchart which shows the procedure of the fuel pressure reduction process in the embodiment. It is a timing chart for explaining an operation of fuel pressure reduction processing in the embodiment, and (a) change in accelerator opening, (b) fuel cut request at the time of transition from high load operation to low load operation. (C) The timing chart which shows together the transition of the fuel pressure in a high pressure delivery pipe.

  Hereinafter, with reference to FIG. 1 to FIG. 6, an embodiment in which the control device for an internal combustion engine according to the present invention is embodied as a control device for an in-line four-cylinder gasoline engine (hereinafter, internal combustion engine) mounted on a vehicle. A form is demonstrated.

FIG. 1 schematically shows a schematic configuration of an internal combustion engine and its control device.
As shown in FIG. 1, the four cylinders # 1 to # 4 of the internal combustion engine 7 are injected with a high-pressure fuel injection valve 47 that directly injects fuel toward the combustion chamber 71 and a fuel toward the intake port 72. A low-pressure fuel injection valve 37 to be supplied is provided. The crankshaft 73 that is the output shaft of the internal combustion engine 7 is rotated by the combustion energy when the fuel injected and supplied from at least one of the high pressure fuel injection valve 47 and the low pressure fuel injection valve 37 is combusted in the combustion chamber 71.

Next, the configuration of the low pressure fuel supply system 3 that supplies fuel to the low pressure fuel injection valve 37 will be described.
The low-pressure fuel supply system 3 includes a low-pressure fuel passage 32 for supplying the fuel pumped up from the fuel tank 1 by the feed pump 2 to the low-pressure fuel injection valve 37. The low pressure fuel passage 32 is connected to the feed pump 2 via a filter 33. The low pressure fuel passage 32 includes a low pressure delivery pipe 36 that stores fuel discharged from the feed pump 2 and supplies the fuel to the low pressure fuel injection valve 37. Further, inside the fuel tank 1, there is provided a return passage 34 having one end connected to the middle of the low pressure fuel passage 32 and the other end opened to the inside of the fuel tank 1. The return passage 34 is provided with a pressure regulator 35 for maintaining the fuel pressure in the low pressure fuel passage 32 at the reference pressure P1. The pressure regulator 35 is a pressure operating valve that opens when the fuel pressure in the low pressure fuel passage 32 exceeds a preset reference pressure P1, and the fuel in the low pressure fuel passage 32 is opened by opening the operation valve. Is returned to the fuel tank 1 through the return passage 34. Incidentally, the reference pressure P1 is set based on the discharge capacity of the feed pump 2 and the like.

Next, the configuration of the high-pressure fuel supply system 4 that supplies fuel to the high-pressure fuel injection valve 47 will be described.
The high-pressure fuel supply system 4 includes a suction passage 41 connected in the middle of the low-pressure fuel passage 32, a high-pressure fuel pump 5 that boosts and discharges fuel sucked through the suction passage 41, and the high-pressure fuel pump 5. A high-pressure fuel passage 42 for supplying the discharged fuel to the high-pressure fuel injection valve 47 is provided. The high-pressure fuel passage 42 includes a high-pressure delivery pipe 46 that stores fuel discharged from the high-pressure fuel pump 5 and supplies the fuel to the high-pressure fuel injection valve 47. A check valve 43 is provided in the middle of the high-pressure fuel passage 42. The check valve 43 is a pressure actuated valve that opens when the fuel pressure on the downstream side of the valve 43, that is, on the high pressure fuel pump 5 side exceeds the reference pressure P2, and from the high pressure fuel pump 5 side to the high pressure delivery pipe. Fuel is passed only to the 46 side. The reference pressure P2 is set to a relatively low pressure.

  The high-pressure fuel pump 5 is a plunger that reciprocates in the cylinder 52 based on the rotation of the cam 62 attached to the exhaust camshaft 61 that rotates with the rotation of the crankshaft 73 of the internal combustion engine 7 and the biasing force of the coil spring 51. 53. With respect to the exhaust camshaft 61 to which the cam 62 for reciprocating the plunger 53 is attached, rotation transmission from the crankshaft 73 is performed so that the crankshaft 73 of the internal combustion engine 7 rotates once during two rotations. Is to be done. Further, the cam 62 is formed with three cam peaks at equal intervals in the rotation direction of the exhaust camshaft 61.

  The high-pressure fuel pump 5 is formed with a pressurizing chamber 54 that is partitioned by a plunger 53 and a cylinder 52 and whose volume changes as the plunger 53 reciprocates. As the cam 62 rotates, the suction stroke in which the plunger 53 moves in the direction of expanding the pressurizing chamber 54 and the pressure feed stroke in which the plunger 53 moves in the direction of reducing the pressurizing chamber 54 are alternately performed. Repeated. The suction stroke is a stroke in which the fuel from the feed pump 2 is sucked into the pressurizing chamber 54 via the suction passage 41, and the pressure feeding stroke is performed by pressurizing the fuel in the pressurizing chamber 54 to the high-pressure fuel passage 42. This is the discharge stroke. The fuel discharged from the high pressure fuel pump 5 in this pressure feeding stroke is supplied to the high pressure fuel injection valve 47 through the high pressure fuel passage 42.

  Further, the high-pressure fuel pump 5 is provided with an electromagnetic spill valve 55 that opens and closes so as to communicate and block between the suction passage 41 and the pressurizing chamber 54. The electromagnetic spill valve 55 includes an electromagnetic solenoid 56 and opens and closes by controlling a voltage applied to the solenoid 56. That is, in the state where the energization to the electromagnetic solenoid 56 is stopped, the electromagnetic spill valve 55 is opened by the urging force of the coil spring 57, and the suction passage 41 and the pressurizing chamber 54 are in communication with each other. When the electromagnetic solenoid 56 is energized, the electromagnetic spill valve 55 is closed against the biasing force of the coil spring 57, and the suction passage 41 and the pressurizing chamber 54 are shut off.

  In the high-pressure fuel pump 5, the electromagnetic spill valve 55 is opened during the intake stroke, thereby permitting fuel to flow from the intake passage 41 into the pressurizing chamber 54. Further, in the pressure feed stroke, the electromagnetic spill valve 55 is closed only for a predetermined period. During the opening of the spill valve 55, the fuel in the pressurizing chamber 54 overflows into the suction passage 41, and the spill The overflow is prohibited while the valve 55 is closed. Thus, when the overflow of the fuel is prohibited, the fuel in the pressurizing chamber 54 is discharged into the high pressure fuel passage 42 in a pressurized state. Therefore, the fuel discharge amount of the high-pressure fuel pump 5 is adjusted by controlling the closing time of the electromagnetic spill valve 55 in the pressure feed stroke and adjusting the amount of fuel overflowing from the pressurizing chamber 54 to the suction passage 41. be able to.

  At one end of the high-pressure delivery pipe 46, a relief passage 48 is provided via a relief valve 49 for maintaining the fuel pressure in the pipe 46 below a preset reference pressure P3 (>> P2). The relief valve 49 opens when the fuel pressure in the pipe 46 exceeds the reference pressure P3, and the fuel in the high-pressure delivery pipe 46 passes through the relief passage 48 by opening the operation valve. Returned to the tank 1. Incidentally, the reference pressure P3 is set to a size that can suppress the fuel pressure in the high-pressure delivery pipe 46 from becoming excessively high.

  Various controls of the internal combustion engine 7 including the fuel injection control of the low pressure fuel injection valve 37, the fuel injection control of the high pressure fuel injection valve 47, and the fuel discharge amount control of the high pressure fuel pump 5 are performed by the electronic control device 8. The electronic control unit 8 includes a central processing unit (hereinafter referred to as CPU), a read only memory (hereinafter referred to as ROM), a random access memory (hereinafter referred to as RAM), and an input / output port (hereinafter referred to as I / O). Here, the CPU executes various arithmetic processes related to various controls. The ROM stores programs and data used for the various controls. The RAM temporarily stores the calculation results of the CPU, the detection results of various sensors, and the like. The I / O mediates exchange of signals with the outside.

Various sensors including the following sensors are connected to the input port of the electronic control unit 8.
A crank position sensor that outputs a pulse signal corresponding to the rotation of the crankshaft 73 of the internal combustion engine 7 and is used for detection of the engine rotational speed NE and the like.

A cam position sensor that outputs a signal corresponding to the rotational position of the shaft 61 in response to the rotation of the exhaust cam shaft 61 of the internal combustion engine 7.
A throttle opening sensor that outputs a signal corresponding to the opening (hereinafter, throttle opening TA) of a throttle valve (not shown) of the internal combustion engine 7.

An accelerator opening sensor that outputs a signal corresponding to the amount of depression of an accelerator pedal (not shown) of the vehicle (hereinafter referred to as accelerator opening ACCP).
A fuel pressure sensor 81 that detects the fuel pressure PHD in the high pressure delivery pipe 46.

Connected to the output port of the electronic control unit 8 are drive circuits of various devices such as a high pressure fuel injection valve 47, a low pressure fuel injection valve 37, an electromagnetic spill valve 55, an ignition valve, and a throttle valve.
The electronic control device 8 outputs a command signal to the drive circuit of various devices connected to the output port in accordance with the engine operation state grasped by the detection signals from the various sensors, and executes control of those devices. . Thus, the fuel injection control of the high pressure fuel injection valve 47 and the low pressure fuel injection valve 37 in the internal combustion engine 7, the fuel discharge amount control of the high pressure fuel pump 5, the ignition timing control by the ignition valve (not shown), the intake air amount control by the throttle valve, etc. Various controls are performed by the electronic control unit 8.

  In the fuel discharge amount control of the high-pressure fuel pump 5, the target value of the fuel pressure in the high-pressure delivery pipe 46 is set according to the engine speed NE and the engine load KL. Specifically, in order to enable fuel injection from the high-pressure fuel injection valve 47 against the pressure in the combustion chamber that becomes high pressure, as shown in FIG. 2, when the engine speed NE is high, it is lower than when it is low. Also, when the engine load KL is high, the target value of the fuel pressure is made higher than when it is low. Then, based on the target value and the fuel pressure PHD detected by the fuel pressure sensor 81, a fuel discharge amount necessary for setting the fuel pressure PHD to the target value is calculated, and the fuel discharge amount and the cam position sensor are used. The voltage applied to the electromagnetic solenoid 56 is controlled in accordance with the position of the plunger 53 grasped based on the detection result. Thereby, the valve closing time of the electromagnetic spill valve 55 during the pumping stroke of the high pressure fuel pump 5 is controlled, and the fuel discharge amount from the high pressure fuel pump 5 is controlled.

  In the fuel injection control, a total amount of fuel injected from both the high pressure fuel injection valve 47 and the low pressure fuel injection valve 37 (hereinafter referred to as total fuel injection amount) Qtotal is set according to the engine speed NE and the engine load KL. To do. Further, as shown in FIG. 3, the ratio of the amount of fuel injected from the high-pressure fuel injection valve 47 in the total fuel injection amount Qtotal in accordance with the engine speed NE and the engine load KL (hereinafter referred to as a high-pressure basic ratio Kdbase (= 1− Kpbase) and 0 ≦ Kdbase ≦ 1) are set. That is, the value obtained by subtracting the high pressure basic ratio Kdbase from “1” is the ratio of the fuel amount injected from the low pressure fuel injection valve 37 in the total fuel injection amount Qtotal (hereinafter, low pressure basic ratio Kpbase, 0 ≦ Kpbase ≦ 1). is there. Here, the high pressure basic ratio Kdbase (low pressure basic ratio Kpbase) is a value that can accurately reduce the fuel consumption of the internal combustion engine 7 and reduce the torque fluctuation of the internal combustion engine 7 in the engine operating state at that time. It is preset through experiments and the like. The fuel injection amounts QD and QP are calculated by multiplying the total fuel injection amount Qtotal by the basic ratios Kpbase and Kdbase, and the fuel injection valves 37 and 47 are calculated based on the fuel injection amounts QP and QD. To control the voltage applied. Thereby, the valve opening time of each fuel injection valve 37 and 47 is controlled, and the fuel injection amount from each fuel injection valve 37 and 47 is controlled.

  In the fuel injection control, a fuel cut request is issued on the condition that the accelerator opening ACCP is fully closed when the engine rotational speed NE is equal to or higher than a predetermined rotational speed, and each fuel injection valve 37, 47 is accompanied by the request. The fuel injection is stopped and fuel cut is performed. During the fuel cut, when the accelerator opening ACCP is opened or the engine speed is lower than the return rotational speed lower than the predetermined rotational speed, the fuel cut request is stopped and each fuel injection valve 37, Fuel injection from 47 is resumed.

  By the way, fuel injection by the high pressure fuel injection valve 47 is performed by displacing the valve body by energizing the injection valve 47. Further, in order to open the high pressure fuel injection valve 47, it is necessary to apply a force for displacing the valve body in the valve opening direction against the fuel pressure acting on the valve body in the valve closing direction. is there. For this reason, when the energization time for the high-pressure fuel injection valve 47 is set to be excessively short, fuel injection may not be performed suitably. Therefore, as shown in FIG. 4, as the fuel pressure PHD in the high pressure delivery pipe 46 is higher, the lower limit value QDmin of the fuel injection amount, that is, the lower limit value of the energization time for the high pressure fuel injection valve 47 is set larger. .

  By the way, in such a control device for an internal combustion engine, as described above, the following problems may occur. That is, when the fuel pressure in the high-pressure delivery pipe 46 is increased during the high-load operation to shift to the low-load operation, the high-pressure fuel pump 5 is designed to reduce the fuel pressure in the high-pressure delivery pipe 46 accordingly. The fuel discharge amount is controlled. However, because there is a time delay for the actual fuel pressure to drop to the pressure corresponding to the low load operation, the fuel pressure will be lower than the pressure corresponding to the low load operation for a while after shifting to the low load operation. Become high. As a result, there is a possibility that the air-fuel ratio of the air-fuel mixture becomes richer than the target air-fuel ratio and the exhaust properties deteriorate.

  Furthermore, in the present embodiment, for the purpose of improving the exhaust properties, the maximum value of the fuel pressure in the high-pressure delivery pipe 46 is set higher than before in order to further increase the fuel pressure injected from the high-pressure fuel injection valve 47 during high load operation. Also try to increase. However, the time required for the actual fuel pressure to drop to the fuel pressure corresponding to the low load operation when shifting from the high load operation to the low load operation becomes longer as the fuel pressure in the high load operation is increased. As a result, the above-described problem becomes more remarkable.

  On the other hand, in order to reduce the amount of fuel injected from the high pressure fuel injection valve 47 after shifting to the low load operation, the opening time of the high pressure fuel injection valve 47 is shortened, that is, the energization time for the high pressure fuel injection valve 47. It is conceivable to shorten the length. However, as described above, when the fuel pressure in the high-pressure delivery pipe 46 is high, the lower limit value of the energization time for the high-pressure fuel injection valve 47 is set accordingly, so the energization time is shortened and the high-pressure fuel injection is performed. There is a limit to reducing the amount of fuel injected from the valve 47.

  The high pressure fuel pump 5 is provided with a leak mechanism (not shown) for leaking fuel in order to reduce the fuel pressure in the high pressure delivery pipe 46, but the fuel pressure is reduced early by the leak mechanism. There are limits to this.

  Therefore, in the present embodiment, the following fuel pressure reduction process is performed through the electronic control unit 8. That is, when the fuel pressure PHD is equal to or higher than the predetermined pressure Pth (KL) during low load operation of the internal combustion engine 7, the ratio of the amount of fuel injected from the high pressure fuel injection valve 47 (hereinafter referred to as the high pressure correction ratio Kd (= 1). -Kp)) is corrected to be larger than the basic ratio Kdbase. Here, “Kp” is a ratio of the amount of fuel injected from the low-pressure fuel injection valve 37 (hereinafter, low-pressure correction ratio). That is, when the fuel pressure PHD is less than the predetermined pressure Pth (KL) corresponding to the low load operation, the high pressure fuel injection valve 47 and the basic ratios Kdbase and Kpbase set by the engine speed NE and the engine load KL Fuel is injected from the low-pressure fuel injection valve 37. On the other hand, when the fuel pressure PHD is equal to or higher than the predetermined pressure Pth (KL) corresponding to the low load operation, the fuel from the high pressure fuel injection valve 47 and the low pressure fuel injection valve 37 is corrected with the corrected correction ratios Kd and Kp. The injection is performed. As a result, the fuel pressure in the high-pressure delivery pipe 46 can be quickly reduced, and the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio because the fuel pressure is higher than the pressure corresponding to the low load operation. The period during which the air-fuel ratio in the high-pressure delivery pipe 46 is reduced due to the time delay of the fuel pressure drop in the high-pressure delivery pipe 46 is accurately suppressed from shifting to the rich side from the target air-fuel ratio.

  Next, the fuel pressure reduction process according to the present embodiment will be described with reference to the flowchart of FIG. The series of processes shown in this flowchart is repeatedly executed at predetermined intervals during the operation of the internal combustion engine 7.

  As shown in FIG. 5, in this series of processing, first, it is determined whether or not the fuel pressure PHD in the high-pressure delivery pipe 46 is equal to or higher than a predetermined pressure Pth (KL) (step S11). The predetermined pressure Pth (KL) is a value set according to the engine load KL, and is set to a value larger than the target value of the fuel pressure in the high-pressure delivery pipe 46 during low load operation. Here, when it is determined that the fuel pressure PHD is less than the predetermined pressure Pth (KL) (step S11: “NO”), the series of processes is temporarily ended.

  On the other hand, when it is determined in step S11 that the fuel pressure PHD is equal to or higher than the predetermined pressure Pth (KL) (step S11: “YES”), the process proceeds to step S12, and currently in low load operation. Judge whether there is. Here, when it is not the low load operation, it is not necessary to reduce the fuel pressure, and this series of processes is temporarily ended.

  On the other hand, if it is determined in step S12 that the operation is a low load operation (step S12: “YES”), the process proceeds to step S13 to determine whether or not the low pressure basic ratio Kpbase is “0”. To do. Here, when it is determined that the low pressure basic ratio Kpbase is “0” (step S14: “YES”), the process proceeds to step S14, where the total fuel is calculated as the fuel injection amount QD of the high pressure fuel injection valve 47. In addition to setting the injection amount Qtotal, “0” is set as the fuel injection amount QP of the low-pressure fuel injection valve 37, and this series of processing is temporarily ended.

  On the other hand, when it is determined in step S13 that the low pressure basic ratio Kpbase is not “0” (step S14: “NO”), the process proceeds to step S15, where the total fuel injection amount Qtotal is set to the high pressure fuel injection valve. It is determined whether or not the lower limit value QDmin of the fuel injection amount 47 and the lower limit value QPmin of the fuel injection amount of the low pressure fuel injection valve 37 are smaller than the sum (= QDmin + QPmin). Here, if it is determined that the total fuel injection amount Qtotal is smaller than the above total (= QDmin + QPmin) (step S15: “YES”), the process proceeds to step S16, where the fuel injection of the high pressure fuel injection valve 47 is performed. The total fuel injection amount Qtotal is set as the amount QD, and “0” is set as the fuel injection amount QP of the low-pressure fuel injection valve 37, and this series of processes is temporarily ended.

  On the other hand, if it is determined in step S15 that the total fuel injection amount Qtotal is equal to or greater than the total sum (= QDmin + QPmin) (step S15: “NO”), the process proceeds to step S17, and the high pressure fuel injection valve 47 is reached. As a fuel injection amount QD, a maximum value QDmax of the fuel amount that can be injected from the injection valve 47 at that time is set, and a fuel injection amount QP of the low pressure fuel injection valve 37 is set from the total fuel injection amount Qtotal to the high pressure fuel injection valve. A value obtained by subtracting the fuel injection amount QD of 47 (= Qtotal−QDmax) is set, and this series of processes is temporarily ended.

  Next, the operation of the fuel pressure reduction process in the present embodiment will be described with reference to the timing chart of FIG. 6 shows (a) the change in accelerator opening ACCP, (b) the change in fuel cut request, and (c) the fuel pressure PHD in the high-pressure delivery pipe 46 at the time of transition from the high load operation to the low load operation. It is a timing chart which shows change of this. Further, in FIG. 6C, the transition of the fuel pressure PHD when the fuel pressure reduction process in the present embodiment is performed is shown by a solid line, and the fuel pressure PHD when the fuel pressure reduction process is not performed is shown. The transition is indicated by a broken line. In addition, the change of the target value of the fuel pressure is indicated by a one-dot chain line.

  As shown in FIG. 6, when the accelerator opening ACCP is set to A2 and the accelerator opening ACCP is fully closed (A0 (<A2)) at timing t1 in the state of high load operation (a Accordingly, the fuel cut request is turned “ON” (b), and the fuel cut is performed.

  At this time, as the accelerator opening ACCP is fully closed, as shown by a one-dot chain line in FIG. 6, the target value of the fuel pressure in the high pressure delivery pipe 46 is changed from the previous PHD2 to PHD0 (< PHD2). Along with this, the fuel pressure PHD in the high pressure delivery pipe 46 gradually decreases. Then, at timing t2 when sufficient time has not elapsed from timing t1, the accelerator opening ACCP is increased to A1 (A0 <A1 <A2) (a), and fuel injection is resumed to shift to low load operation. When this occurs, the fuel pressure PHD in the high-pressure delivery pipe 46 becomes higher than the predetermined pressure Pth (KL). At this time, in the conventional control device for an internal combustion engine, fuel injection is performed at the respective basic ratios Kdbase and Kpbase. Therefore, as shown by the broken line in FIG. 6, the fuel pressure PHD remains at a low load until timing t4. The fuel pressure corresponding to the time of operation, that is, a state higher than the target value PHD1 is reached (c). As a result, there is a possibility that the air-fuel ratio of the air-fuel mixture becomes richer than the target air-fuel ratio and the exhaust properties deteriorate.

  On the other hand, in this embodiment, since the fuel injection is performed at the correction ratios Kd and Kp obtained by correcting the basic ratios Kdbase and Kpbase after the timing t2, as shown by the solid line in FIG. The decreasing speed of the fuel pressure PHD increases, and the fuel pressure PHD becomes the target value PHD1 at the timing t3 earlier than the timing t4. Accordingly, the period (t2 to t3) in which the fuel pressure PHD is higher than the target value PHD1 is shorter than the period (t2 to t4) by the conventional control device for the internal combustion engine.

According to the control apparatus for an internal combustion engine according to the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, the fuel pressure in the high-pressure delivery pipe 46 is adjusted according to the engine load KL by controlling the fuel discharge amount from the high-pressure fuel pump 5 through the electronic control unit 8. Further, the basic ratio Kdbase (= 1) of the fuel amount injected from the high-pressure fuel injection valve 47 in the total fuel injection amount Qtotal which is the sum of the fuel amounts injected from both the high-pressure fuel injection valve 47 and the low-pressure fuel injection valve 37. -Kpbase) is set according to the engine speed NE and the engine load KL. When the fuel pressure PHD is higher than a predetermined pressure Pth (KL) higher than the fuel pressure corresponding to the low load operation during the low load operation of the internal combustion engine 7, the high pressure fuel injection valve 47 at the total fuel injection amount Qtotal The ratio Kd (= 1−Kp) of the injected fuel amount is corrected to be larger than the basic ratio Kdbase. That is, when the fuel pressure PHD is less than the predetermined pressure Pth (KL) corresponding to the low load operation, the high pressure fuel injection valve 47 and the basic ratios Kdbase and Kpbase set by the engine speed NE and the engine load KL Fuel is injected from the low-pressure fuel injection valve 37. On the other hand, when the fuel pressure PHD is equal to or higher than the predetermined pressure Pth (KL) corresponding to the low load operation, the fuel from the high pressure fuel injection valve 47 and the low pressure fuel injection valve 37 is corrected with the corrected correction ratios Kd and Kp. The injection is performed. When the fuel pressure in the high-pressure delivery pipe 46 is increased during the high-load operation and the operation is shifted to the low-load operation, the discharge amount of the high-pressure fuel pump 5 is set to lower the fuel pressure in the high-pressure delivery pipe 46 accordingly. Is controlled. However, because there is a time delay for the actual fuel pressure to drop to the pressure corresponding to the low load operation, the fuel pressure will be lower than the pressure corresponding to the low load operation for a while after shifting to the low load operation. Become high. At this time, according to the above configuration, assuming that the fuel pressure PHD in the high-pressure delivery pipe 46 is equal to or higher than the predetermined pressure Pth (KL), the correction ratio Kd of the fuel amount injected from the high-pressure fuel injection valve 47 is the engine speed. It is made larger than the basic ratio Kdbase set according to the speed NE and the engine load KL. Thus, by actively consuming the fuel in the high-pressure delivery pipe 46, the fuel pressure in the pipe 46 can be quickly reduced, and the fuel pressure is higher than the pressure corresponding to the low load operation. As a result, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be shortened. Therefore, it is possible to accurately suppress the air-fuel ratio of the air-fuel mixture from shifting to the rich side from the target air-fuel ratio due to the time delay of the fuel pressure drop in the high-pressure delivery pipe 46.

  (2) Further, in the present embodiment, the total fuel injection amount Qtotal is set to the lower limit value QDmin of the fuel amount injected from the high pressure fuel injection valve 47 and the fuel amount injected from the low pressure fuel injection valve 37 through the electronic control unit 8. Is smaller than the sum (= QDmin + QPmin) of the lower limit value QPmin, the fuel injection from the low pressure fuel injection valve 37 is prohibited and the total fuel injection amount Qtotal is injected from the high pressure fuel injection valve 47. As a result, the total fuel injection amount Qtotal is injected by the high-pressure fuel injection valve 47, so that fuel in the high-pressure delivery pipe 46 is actively consumed, thereby reducing the fuel pressure in the pipe 46 at an early stage. Therefore, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio due to the fuel pressure being higher than the pressure corresponding to the low load operation can be shortened.

  (3) In the present embodiment, the total fuel injection amount Qtotal is determined by the electronic control unit 8 so that the lower limit value QDmin of the fuel amount injected from the high-pressure fuel injection valve 47 and the fuel amount injected from the low-pressure fuel injection valve 37. Is equal to or higher than the sum (= QDmin + QPmin) of the lower limit value QPmin, the correction ratio Kd of the fuel amount injected from the high pressure fuel injection valve 47 is set to the maximum amount of fuel that can be injected from the high pressure fuel injection valve 47 at that time. Correction is made so that the value QDmax is obtained. As a result, the maximum fuel amount QDmax that can be injected at that time is injected from the high-pressure fuel injection valve 47. Thus, by actively consuming the fuel in the high-pressure delivery pipe 46, the fuel pressure in the pipe 46 can be quickly reduced, and the fuel pressure is higher than the pressure corresponding to the low load operation. As a result, the period during which the air-fuel ratio of the air-fuel mixture is richer than the target air-fuel ratio can be shortened.

  Note that the control device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following forms appropriately modified.

  -The control apparatus of the internal combustion engine which concerns on this invention is not restricted to what is applied with respect to the inline 4 cylinder type gasoline engine. In addition, for example, the present invention can be applied to an internal combustion engine having 5 cylinders or more and an internal combustion engine having 3 cylinders or less. Further, the present invention is not limited to a series internal combustion engine, and the present invention can be applied to other internal combustion engines such as a V-type internal combustion engine and a horizontally opposed internal combustion engine.

  In the above embodiment, at the timing t1 of the high-load operation state, the fuel cut request is turned “ON” in accordance with the accelerator opening ACCP being fully closed (the previous FIG. 6). reference). Alternatively, the fuel cut may be executed after a predetermined period after the execution condition of the fuel cut (here, the accelerator opening ACCP is fully closed) is satisfied from the high load operation state. . That is, fuel cut delay control may be employed. Thereby, even if the accelerator opening ACCP is fully closed in the high load operation state, the high load operation state is continued for the predetermined period, and the fuel from the high pressure fuel injection valve 47 is continued. The consumption of fuel in the delivery pipe 46 is promoted, so that the fuel pressure in the pipe 46 can be lowered early. The predetermined period is a value set in advance through experiments or the like.

  However, even when the fuel cut delay control is performed in this way, the fuel pressure PHD may become higher than the fuel pressure corresponding to the low load operation when the operation is subsequently shifted to the low load operation. Therefore, when the fuel pressure PHD in the high-pressure delivery pipe 46 is higher than the pressure corresponding to the low-load operation, the high-pressure fuel injection at the total fuel injection amount Qtotal is compared to the case where the fuel pressure PHD is lower than the pressure corresponding to the low-load operation. The ratio Kd of the fuel amount injected from the valve 47 may be increased. As a result, it is possible to more accurately suppress the air-fuel ratio of the air-fuel mixture from shifting to the rich side from the target air-fuel ratio due to the time delay of the fuel pressure drop in the high-pressure delivery pipe 46.

  In the above embodiment, the total fuel injection amount Qtotal is injected from the low-pressure fuel injection valve 37 and the lower limit value QDmin of the fuel amount injected from the high-pressure fuel injection valve 47 when shifting from the high load operation to the low load operation. When the fuel amount is equal to or greater than the sum (= QDmin + QPmin) of the lower limit value QPmin of the fuel amount, the correction amount Kd of the fuel amount injected from the high-pressure fuel injection valve 47 is the fuel amount that can be injected from the high-pressure fuel injection valve 47 The maximum value QDmax was set. Further, when shifting from the high load operation to the low load operation, the total fuel injection amount Qtotal is the lower limit value QDmin of the fuel amount injected from the high pressure fuel injection valve 47 and the fuel amount injected from the low pressure fuel injection valve 37. When it is smaller than the sum (= QDmin + QPmin) with the lower limit value QPmin, the correction ratio Kp of the fuel amount injected from the low pressure fuel injection valve 37 is set to “0”. That is, the fuel injection from the low pressure fuel injection valve 37 is prohibited, and the total fuel injection amount Qtotal is injected by the high pressure fuel injection valve 47. However, the correction ratio Kd for fuel injected from the high-pressure fuel injection valve 47 is not limited to that exemplified in the above embodiment, and the ratio of the amount of fuel injected from the high-pressure fuel injection valve 47 is increased. When there is a concern about the occurrence of problems such as an increase in fuel consumption of the internal combustion engine 7 and an increase in torque fluctuation due to the above, the ratio Kd of the amount of fuel injected from the high pressure fuel injection valve 47 in the above embodiment. What is necessary is just to make smaller than what was illustrated. That is, the ratio of the amount of fuel injected from the high-pressure fuel injection valve 47 may be increased within a range in which an increase in fuel consumption of the internal combustion engine 7 and an increase in torque fluctuation are allowed.

  In the above embodiment, the fuel pressure in the high pressure delivery pipe 46 is adjusted by the high pressure fuel pump 5 according to both the engine speed NE and the engine load KL, but only the engine speed NE or the engine load It is also possible to adjust the fuel pressure according to KL alone. Further, the parameters for adjusting the fuel pressure in the high pressure delivery pipe 46 are not limited to the engine speed NE and the engine load KL. Other parameters such as the total fuel injection amount Qtotal are grasped. Other parameters can also be employed.

  In the above embodiment, when the fuel pressure in the high pressure delivery pipe 46 (high pressure fuel passage) is higher than the pressure corresponding to the engine operating state, the total pressure is lower than the pressure corresponding to the engine operating state. It illustrated about what enlarges the ratio of the fuel quantity injected from the high pressure fuel injection valve in the fuel injection quantity. However, the present invention is not limited to this, and when the fuel pressure in the high-pressure fuel passage is lower than the pressure corresponding to the engine operating state, compared to the case where the pressure is higher than the pressure corresponding to the engine operating state, It is also possible to reduce the proportion of the fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount. In this case, the fuel pressure in the high-pressure fuel passage can be increased early by actively suppressing the fuel consumption in the high-pressure fuel passage as compared with the conventional control configuration in which such a ratio is not changed. The period during which the air-fuel ratio of the air-fuel mixture is leaner than the target air-fuel ratio due to the fuel pressure being lower than the pressure corresponding to the engine operating state can be shortened. In addition, there is a concern that problems such as an increase in fuel consumption of the internal combustion engine and an increase in torque fluctuation may be caused by reducing the ratio of the amount of fuel injected from the high-pressure fuel injection valve. Therefore, it is desirable to reduce the ratio of the amount of fuel injected from the high pressure fuel injection valve within a range in which such an increase in fuel consumption and an increase in torque fluctuation are allowed.

  DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 2 ... Feed pump, 3 ... Low pressure fuel supply system, 32 ... Low pressure fuel passage, 33 ... Filter, 34 ... Return passage, 35 ... Pressure regulator, 36 ... Low pressure delivery pipe, 37 ... Low pressure fuel injection valve, DESCRIPTION OF SYMBOLS 4 ... High pressure fuel supply system, 41 ... Intake passage, 42 ... High pressure fuel passage, 43 ... Check valve, 46 ... High pressure delivery pipe, 47 ... High pressure fuel injection valve, 48 ... Relief passage, 49 ... Relief valve, 5 ... High pressure fuel Pump (adjustment mechanism), 51 ... coil spring, 52 ... cylinder, 53 ... plunger, 54 ... pressurizing chamber, 55 ... electromagnetic spill valve, 55a ... connection port, 56 ... electromagnetic solenoid, 57 ... coil spring, 61 ... exhaust cam Shaft, 62 ... cam, 7 ... internal combustion engine, 71 ... cylinder, 72 ... intake port, 73 ... crankshaft, 8 ... electronic control unit (setting , The correction unit), 81: fuel pressure sensor.

Claims (8)

A high-pressure fuel injection valve for directly injecting fuel in the high-pressure fuel passage into the cylinder, a low-pressure fuel injection valve for injecting fuel in the low-pressure fuel injection passage to the intake port of the cylinder, and depending on the engine operating state Applied to an internal combustion engine having an adjustment mechanism for adjusting the fuel pressure in the high-pressure fuel passage, in a total fuel injection amount that is the sum of the fuel amounts injected from both the high-pressure fuel injection valve and the low-pressure fuel injection valve A control device for an internal combustion engine that sets a ratio of the amount of fuel injected from the high-pressure fuel injection valve in accordance with an engine operating state,
When the fuel pressure in the high-pressure fuel passage is higher than the pressure corresponding to the engine operating state, the fuel pressure from the high-pressure fuel injection valve in the total fuel injection amount is lower than the pressure corresponding to the engine operating state. A control apparatus for an internal combustion engine, characterized by increasing a ratio of a fuel amount to be injected. The control apparatus for an internal combustion engine according to claim 1,
A setting unit that sets a ratio of the amount of fuel injected from the high-pressure fuel injection valve in the total fuel injection amount according to an engine operating state;
When the fuel pressure in the high-pressure fuel passage is higher than the pressure corresponding to the engine operating state, the ratio of the fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount is set by the setting unit A correction unit that corrects larger than the ratio,
When the fuel pressure in the high pressure fuel passage is equal to or lower than the pressure corresponding to the engine operating state, the fuel is injected from the high pressure fuel injection valve and the low pressure fuel injection valve at a rate set by the setting unit. On the other hand, when the fuel pressure in the high pressure fuel passage is higher than the pressure corresponding to the engine operating state, the fuel from the high pressure fuel injection valve and the low pressure fuel injection valve is corrected at the rate corrected by the correction unit. A control apparatus for an internal combustion engine, characterized in that The control apparatus for an internal combustion engine according to claim 2,
The control unit for an internal combustion engine, wherein the setting unit sets a ratio of a fuel amount injected from the high-pressure fuel injection valve in the total fuel injection amount according to an engine speed and an engine load. The control apparatus for an internal combustion engine according to claim 2 or 3,
The fuel pressure in the high-pressure fuel passage is adjusted according to the engine load by the adjusting mechanism,
The correction unit is injected from the high-pressure fuel injection valve when the fuel pressure in the high-pressure fuel passage is not less than a predetermined pressure higher than the fuel pressure corresponding to the low-load operation during low-load operation of the internal combustion engine. A control apparatus for an internal combustion engine, wherein the ratio of the fuel amount is corrected to be larger than the ratio set by the setting unit. The control device for an internal combustion engine according to any one of claims 2 to 4,
The correction unit is configured such that a total fuel injection amount that is a sum of fuel amounts injected from both the high pressure fuel injection valve and the low pressure fuel injection valve is a lower limit value of the fuel amount injected from the high pressure fuel injection valve and the When the sum of the fuel amount injected from the low-pressure fuel injection valve is smaller than the lower limit of the fuel amount, the fuel injection from the low-pressure fuel injection valve is prohibited and the total fuel injection amount is injected from the high-pressure fuel injection valve A control device for an internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 2 to 5,
The correction unit is configured such that a total fuel injection amount that is a sum of fuel amounts injected from both the high pressure fuel injection valve and the low pressure fuel injection valve is a lower limit value of the fuel amount injected from the high pressure fuel injection valve and the If the sum of the fuel amount injected from the low pressure fuel injection valve is not less than the sum of the lower limit values, the ratio of the fuel amount injected from the high pressure fuel injection valve is the fuel that can be injected from the high pressure fuel injection valve at that time. A control apparatus for an internal combustion engine, wherein the correction is performed so that the maximum value is obtained. A high-pressure fuel injection valve for directly injecting fuel in the high-pressure fuel passage into the cylinder, a low-pressure fuel injection valve for injecting fuel in the low-pressure fuel injection passage to the intake port of the cylinder, and depending on the engine operating state Applied to an internal combustion engine having an adjustment mechanism for adjusting the fuel pressure in the high-pressure fuel passage, in a total fuel injection amount that is the sum of the fuel amounts injected from both the high-pressure fuel injection valve and the low-pressure fuel injection valve A control device for an internal combustion engine that sets a ratio of the amount of fuel injected from the high-pressure fuel injection valve in accordance with an engine operating state,
When the fuel pressure in the high-pressure fuel passage is lower than the pressure corresponding to the engine operating state, the fuel pressure from the high-pressure fuel injection valve in the total fuel injection amount is higher than the case where the fuel pressure is higher than the pressure corresponding to the engine operating state. A control apparatus for an internal combustion engine, characterized in that a ratio of a fuel amount to be injected is reduced. In the control device for an internal combustion engine according to any one of claims 1 to 7,
The control apparatus for an internal combustion engine, wherein the adjustment mechanism is a high-pressure fuel pump that is provided in the high-pressure fuel passage and pumps fuel into the passage.

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