JP2009221917A - Fuel supply system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure an appropriate amount of fuel according to fluctuations in fuel pressure in a fuel supply system of an internal combustion engine, so as to suppress variations in an air-fuel ratio, thereby preventing degradation in combustion or emissions. <P>SOLUTION: The fuel supply system includes: a feed pump 83 for pressurizing the fuel; a high-pressure fuel pump 85 for boosting a low-pressure fuel; a pressure chamber 103 for passing the low-pressure fuel through without being boosted by the high-pressure fuel pump 85; injectors 62, 63 for injecting the fuel into combustion chambers 22, 23; and an ECU 70 for controlling the halting of boosting the low-pressure fuel by the high-pressure fuel pump 85 and its operation depending on an engine operation state and for setting a fuel injection time for the injectors 62, 63 based on a fuel pressure mean value at a predetermined fuel pressure set time, wherein, when switching the high-pressure fuel pump 85 from its operating state to halted state, the ECU 70 sets the fuel injection time for the injectors 62, 63 based on the fuel pressure detected by a fuel pressure sensor 78, over a predetermined fuel change time after that switching. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel supply device for an internal combustion engine capable of boosting low-pressure fuel into high-pressure fuel and injecting the high-pressure fuel into a combustion chamber of the internal combustion engine.

  2. Description of the Related Art In-cylinder injection internal combustion engines that directly inject fuel into a combustion chamber (cylinder) instead of an intake port are known for internal combustion engines such as gasoline engines and diesel engines mounted on vehicles such as passenger cars and trucks. . In this direct injection internal combustion engine, when the intake valve is opened, air is sucked into the combustion chamber from the intake port, and during this intake stroke or during the compression stroke in which the piston rises to compress the intake air, the fuel injection valve burns. Inject fuel directly into the chamber. Then, high-pressure air and mist-like fuel are mixed in the combustion chamber, and the spark plug ignites and explodes with respect to this air-fuel mixture, and the exhaust gas is discharged from the intake port when the exhaust valve is opened.

  In such a fuel system in a direct injection internal combustion engine, in order to atomize the fuel, the fuel in the fuel tank is pumped up by an electric low pressure fuel pump and pressurized to a predetermined low pressure, and the low pressure fuel is injected into the internal combustion engine. The high pressure fuel is pressurized by a high pressure fuel pump, the high pressure fuel is stored in a delivery pipe, and is injected into each combustion chamber by a plurality of fuel injection valves attached to the delivery pipe. In such a high-pressure fuel pump, the plunger is reciprocated by a cam interlocked with the crankshaft to pressurize the fuel. In this case, the reciprocating movement of the plunger has a suction stroke that moves in a direction that increases the volume of the pressure chamber, and a pressure-feed stroke that moves in a direction that decreases the volume of the pressure chamber. A metering valve is provided in the fuel intake passage that communicates with the pressure chamber. By opening the metering valve during the intake stroke, fuel is sucked into the pressure chamber through the fuel intake passage. By closing the metering valve, the fuel in the pressure chamber is discharged after being pressurized to a predetermined pressure, and by controlling the opening / closing timing of the metering valve, the discharge amount of high-pressure fuel can be adjusted. it can.

  In the fuel system in the above-described cylinder injection internal combustion engine, the plunger is reciprocated by a cam interlocked with the crankshaft, so that the position of the plunger corresponding to the crank angle is detected, and the metering valve is opened and closed accordingly. By setting the timing, proper fuel metering is possible. However, in a relatively quiet operating state such as an idling operation of the internal combustion engine, there is a problem that the operation noise accompanying the opening and closing of the metering valve becomes remarkable and silence is hindered.

  Therefore, for example, in Patent Document 1 below, two high-pressure fuel pumps for boosting low-pressure fuel are provided, and when the amount of fuel required by the internal combustion engine is small, the operation of one of the two high-pressure fuel pumps is stopped, The operating frequency of the high-pressure fuel pump accompanying the opening / closing operation is reduced by reducing the number of times of operation of the entire pump in a predetermined period and reducing the operating frequency of the electromagnetic spill valve.

JP 2002-213326 A

  As described above, in a cylinder injection internal combustion engine, fuel is pressurized to a low pressure by a low-pressure fuel pump, the low-pressure fuel is pressurized to a high pressure by a high-pressure fuel pump, and the high-pressure fuel is pumped to a delivery pipe and is injected by a fuel injection valve. Injecting into the combustion chamber. In this case, the fuel injection amount of the fuel injection valve is determined by the injection time, but this fuel injection amount varies according to the fuel pressure. Therefore, the injection time of the fuel injection valve is set based on the fuel injection amount and the fuel pressure. That is, the fuel injection amount is set based on the engine load (intake air amount, etc.), and the fuel pressure is set based on the detection value of the fuel pressure sensor attached to the delivery pipe. However, in the delivery pipe, fuel pulsation occurs due to the pressure increase by the high pressure fuel pump and the fuel injection by the fuel injection valve. Therefore, in the control device, the fuel pressure average value is calculated by averaging the detected values of the fuel pressure sensor for a predetermined time, and the injection time is set using this fuel pressure average value.

  However, when the operation and stop of the high-pressure fuel pump are switched according to the operating state of the internal combustion engine as in the above-described conventional fuel supply device for the internal combustion engine, the fuel pressure greatly fluctuates during this switching. As a result, a deviation occurs between the actual fuel pressure and the average value of the fuel pressure, the actual fuel injection amount is too much or too little relative to the required fuel injection amount, and the air-fuel ratio varies and combustion occurs. There is a problem that emissions deteriorate as well.

  The present invention solves such problems, and by ensuring an appropriate amount of fuel in accordance with fluctuations in fuel pressure, it is possible to suppress variations in air-fuel ratio and prevent deterioration of combustion and emissions. An object is to provide a fuel supply device for an internal combustion engine.

  In order to solve the above-described problems and achieve the object, a fuel supply device for an internal combustion engine according to the present invention includes a fuel pumping unit that pressurizes fuel and pumps it as low-pressure fuel, and a low-pressure pumped by the fuel pumping unit. Boosting means for boosting fuel and pumping it as high-pressure fuel, a fuel passage through which low-pressure fuel from the fuel pumping means is not boosted by the boosting means, and fuel injection for injecting low-pressure fuel or high-pressure fuel into the combustion chamber Means, fuel pressure control means for controlling the stop and operation of boosting of the low-pressure fuel by the boosting means according to the operating state of the internal combustion engine, and the fuel injection means based on the fuel pressure average value at a predetermined fuel pressure setting time An internal combustion engine fuel supply device comprising: a fuel injection control means for setting a fuel injection time; wherein the fuel pressure control means When switched, the fuel injection control means changes the fuel pressure setting time below a predetermined value over a preset predetermined fuel pressure change time from switching of said boosting means, it is characterized in.

  In the fuel supply device for an internal combustion engine of the present invention, a fuel pressure sensor for detecting the pressure of the fuel supplied to the fuel injection means is provided, and the fuel pressure control means causes the pressure increase means to be stopped between a stopped state and an operating state. When switching, the fuel injection control means sets the fuel injection time by the fuel injection means based on the fuel pressure detected by the fuel pressure sensor over a preset fuel pressure change time from the time of switching of the boosting means. It is a feature.

  In the fuel supply apparatus for an internal combustion engine according to the present invention, when the fuel pressure control means switches the boosting means between a stopped state and an operating state, the fuel injection control means is configured to detect the fuel pressure detected by the fuel pressure sensor, or The fuel pressure change time is set based on a fuel pressure average value set based on the fuel pressure detected by the fuel pressure sensor or a deviation between the fuel pressure and the fuel pressure average value.

  In the fuel supply apparatus for an internal combustion engine according to the present invention, when the boosting means is switched from the operating state to the stopped state by the fuel pressure control means, the fuel injection control means has a predetermined preset value from when the boosting means is stopped. The fuel pressure injection amount is increased over the fuel pressure change time.

  In the fuel supply apparatus for an internal combustion engine according to the present invention, when the boosting means is switched from the stopped state to the operating state by the fuel pressure control means, the fuel injection control means has a predetermined preset value from the time of operation of the boosting means. The fuel injection amount is reduced over the fuel pressure change time.

  In the fuel supply device for an internal combustion engine according to the present invention, the fuel injection control means reduces the fuel injection amount over a predetermined fuel pressure change time set in advance from the operation of the boosting means, and decreases the fuel injection amount in order of the fuel injection cylinders. It is characterized by setting.

  According to the fuel supply device for an internal combustion engine of the present invention, the fuel pressure control means for controlling the stop and operation of the boosting of the low-pressure fuel by the boosting means according to the operating state of the internal combustion engine, and the fuel pressure average for a predetermined fuel pressure setting time Fuel injection control means for setting the fuel injection time by the fuel injection means based on the value, and when the fuel pressure control means switches the boosting means between the stopped state and the operating state, the fuel injection control means The fuel pressure setting time is changed to a predetermined value or less over a predetermined fuel pressure changing time set in advance from the time of switching. Therefore, when the boosting means is switched between the stopped state and the operating state, the deviation between the actual fuel pressure and the average fuel pressure value is reduced by changing the fuel pressure setting time to a predetermined value or less over a predetermined fuel pressure change time. Therefore, the deviation of the fuel injection amount corresponding to the fluctuation of the fuel pressure is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio can be suppressed, and the deterioration of combustion and emission can be prevented.

  Embodiments of a fuel supply device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram showing a fuel system in a fuel supply device for an internal combustion engine according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view of an essential part of the internal combustion engine according to the first embodiment. 3-2 is a schematic diagram illustrating a high-pressure fuel pump in the fuel supply apparatus for an internal combustion engine according to the first embodiment, FIG. 4 is a flowchart illustrating operation control of the fuel supply apparatus for the internal combustion engine according to the first embodiment, and FIG. It is a graph showing the injection time with respect to injection amount and fuel pressure.

  In the present embodiment, a V-type 6-cylinder gasoline engine having an in-cylinder fuel injection device is applied as the internal combustion engine. In this V-type 6-cylinder engine (hereinafter simply referred to as an engine), as shown in FIG. 2, the cylinder block 11 has left and right banks 12 and 13 inclined at a predetermined angle at the upper portion. Three cylinder bores 14 and 15 are formed in the cylinders 12 and 13, respectively, and pistons 16 and 17 are fitted to the cylinder bores 14 and 15 so as to be movable up and down. A crankshaft (not shown) is rotatably supported at the lower part of the cylinder block 11, and the pistons 16 and 17 are connected to the crankshaft via connecting rods 18 and 19, respectively.

  On the other hand, cylinder heads 20 and 21 are fastened to the upper portions of the banks 12 and 13 of the cylinder block 11, and the combustion chambers 22 and 23 are constituted by the cylinder block 11, the pistons 16 and 17, and the cylinder heads 20 and 21. ing. The intake ports 24 and 25 and the exhaust ports 26 and 27 are formed on the upper portions of the combustion chambers 22 and 23, that is, the lower surfaces of the cylinder heads 20 and 21 so as to face each other. 27, the lower end portions of the intake valves 28 and 29 and the exhaust valves 30 and 31 are located. The intake valves 28 and 29 and the exhaust valves 30 and 31 are supported by the cylinder heads 20 and 21 so as to be movable in the axial direction, and are attached in a direction to close the intake ports 24 and 25 and the exhaust ports 26 and 27. It is supported. Further, intake camshafts 32 and 33 and exhaust camshafts 34 and 35 are rotatably supported on the cylinder heads 20 and 21, and the intake cams 36 and 37 and the exhaust cams 38 and 39 are interposed via a roller rocker arm (not shown). Are in contact with the upper ends of the intake valves 28 and 29 and the exhaust valves 30 and 31.

  Accordingly, when the intake camshafts 32 and 33 and the exhaust camshafts 34 and 35 rotate in synchronization with the engine, the intake cams 36 and 37 and the exhaust cams 38 and 39 operate the roller rocker arm, and the intake valves 28 and 29 and the exhaust valve 30 and 31 move up and down at a predetermined timing to open and close intake ports 24 and 25 and exhaust ports 26 and 27, intake ports 24 and 25 and combustion chambers 22 and 23, combustion chambers 22 and 23, and exhaust port 26. , 27 can communicate with each other.

  In addition, the valve mechanism of this engine is a variable intake valve timing mechanism (VVT) 40 that controls the intake valves 28 and 29 and the exhaust valves 30 and 31 at an optimal opening / closing timing according to the operating state. 41 and an exhaust variable valve mechanism 42, 43. The intake variable valve operating mechanisms 40 and 41 and the exhaust variable valve operating mechanisms 42 and 43 are configured, for example, by providing VVT controllers at the shaft end portions of the intake camshafts 32 and 33 and the exhaust camshafts 34 and 35. The opening / closing timing of the intake valves 28, 29 and the exhaust valves 30, 31 is advanced or retarded by changing the phase of each camshaft 32, 33, 34, 35 with respect to the cam sprocket by a pump (or electric motor). It is something that can be done. In this case, each variable valve mechanism 40, 41, 42, 43 advances or retards the opening / closing timing with the operating angle (opening period) of intake valves 28, 29 and exhaust valves 30, 31 being constant. The intake camshafts 32, 33 and the exhaust camshafts 34, 35 are provided with cam position sensors 44, 45, 46, 47 for detecting their rotational phases.

  A surge tank 50 is connected to the intake ports 24 and 25 of the cylinder heads 20 and 21 via intake manifolds 48 and 49, and an intake pipe 51 is connected to the surge tank 50. An air cleaner 52 is attached to the intake port. The intake pipe 51 is provided with an electronic throttle device 53 having a throttle valve located on the downstream side of the air cleaner 52. On the other hand, exhaust pipes 56, 57 are connected to the exhaust ports 26, 27 via exhaust manifolds 54, 55. The exhaust pipes 56, 57 are joined by an exhaust collecting pipe 58 and are connected to the exhaust pipes 56, 57. The original catalysts 59 and 60 are attached, and the NOx occlusion reduction type catalyst 61 is attached to the exhaust collecting pipe 58.

  The cylinder heads 20 and 21 are each provided with injectors 62 and 63 for injecting fuel (gasoline) directly into the combustion chambers 22 and 23. The injectors 62 and 63 are attached to delivery pipes 64 and 65, respectively. ing. Therefore, the injectors 62 and 63 can inject the high-pressure fuel stored in the delivery pipes 64 and 65 into the combustion chambers 22 and 23. The cylinder heads 20 and 21 are equipped with spark plugs 66 and 67 that are located above the combustion chambers 22 and 23 and ignite the air-fuel mixture.

  By the way, the vehicle is equipped with an electronic control unit (ECU) 70, which can control the fuel injection timing of each injector 62, 63, the ignition timing of the spark plugs 66, 67, and the like. A fuel injection amount, a fuel injection timing, an ignition timing, and the like are determined based on the detected engine operation state such as the intake air amount, intake air temperature, throttle opening, accelerator opening, engine speed, and coolant temperature.

  That is, an airflow sensor 71 and an intake air temperature sensor 72 are mounted on the upstream side of the intake pipe 51, and the measured intake air amount and intake air temperature are output to the ECU 70. The electronic throttle device 53 is provided with a throttle position sensor 73, and the accelerator pedal is provided with an accelerator position sensor 74, which outputs the current throttle opening and accelerator opening to the ECU 70. Further, a crank angle sensor 75 is provided on the crankshaft, and the detected crank angle is output to the ECU 70, and the ECU 70 calculates the engine speed based on the crank angle. Further, the cylinder block 11 is provided with a water temperature sensor 76 and outputs the detected engine cooling water temperature to the ECU 70. Further, the vehicle is provided with a vehicle speed sensor 77 and outputs the detected vehicle speed to the ECU 70.

  Further, the ECU 70 can control the intake variable valve mechanisms 40 and 41 and the exhaust variable valve mechanisms 42 and 43 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idling, or when the load is light, the exhaust gas 30 is exhausted from the intake port 24, 31 by eliminating the overlap between the exhaust valve 30, 31 opening timing and the intake valve 28, 29 opening timing. 25 or the amount of air blown back to the combustion chambers 22 and 23 is reduced, and combustion stability and fuel efficiency can be improved. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valves 28 and 29 is advanced to reduce the amount of intake air that blows back to the intake ports 24 and 25, thereby improving volumetric efficiency. At the time of high load and high rotation, the closing timing of the intake valves 28 and 29 is retarded according to the rotational speed, thereby improving the volume efficiency as the timing according to the inertial force of the intake air.

  Here, the fuel system of the above-described V-type 6-cylinder gasoline engine of this embodiment will be described in detail.

  In the engine fuel system of this embodiment, as shown in FIG. 1, injectors (fuel injection means) 62, 63 have base ends connected to delivery pipes 64, 65. High-pressure fuel can be injected into the combustion chambers 22 and 23 provided corresponding to the six cylinders of the engine. One delivery pipe 64 is equipped with a fuel pressure sensor 78 that detects the fuel pressure.

  The fuel tank 81 has a vertical shape divided into a first chamber 82a and a second chamber 82b, and can store a predetermined amount of fuel in each of the chambers 82a and 82b. The first chamber 82a is provided with a feed pump (fuel pressure feeding means) 83, and this feed pump 83 is connected to a high pressure fuel pump (pressure raising means) 85 via a low pressure fuel supply pipe 84. 85 is connected to one end of the delivery pipe 64 through a high-pressure fuel supply pipe 86. The high pressure fuel pump 85 can be driven by one intake camshaft 32, a pulsation damper 87 is attached to the low pressure fuel supply pipe 84, and a check valve 88 is attached to the high pressure fuel supply pipe 86.

  The second chamber 82b is provided with a jet pump 89. The jet pump 89 is connected to a fuel return pipe 91 branched from the low-pressure fuel supply pipe 84 and having a pressure regulator 90. A fuel transfer pipe 92 extending to the chamber 82a is connected. Further, the delivery pipes 64 and 65 are connected by a connecting pipe 93, and the base end portion of the fuel discharge pipe 94 is connected to the other end of the other delivery pipe 65, and the delivery in the fuel discharge pipe 94 is performed. A relief valve 95 is attached to the discharge portion of the pipe 65, and the tip end portion of the fuel discharge pipe 94 is connected to the second chamber 82 b in the fuel tank 81. The high-pressure fuel pump 85 is provided with a return pipe 96 that returns excess low-pressure fuel to the fuel tank 81, and the tip is connected to the fuel discharge pipe 94.

  Therefore, when the engine is started, the feed pump 83 is driven to pressurize the fuel in the first chamber 82 a in the fuel tank 81, and low pressure fuel is supplied to the high pressure fuel pump 85 through the low pressure fuel supply pipe 84. The high pressure fuel pump 85 boosts the low pressure fuel and supplies the high pressure fuel to the delivery pipes 64 and 65 through the high pressure fuel supply pipe 86. The injectors 62 and 63 can inject the high-pressure fuel in the delivery pipes 64 and 65 into the combustion chambers 22 and 23. At this time, the ECU 70 drives and controls the high-pressure fuel pump 85 based on the fuel pressure detected by the fuel pressure sensor 78 to maintain the fuel pressure in the delivery pipes 64 and 65 at a predetermined pressure.

  When the fuel pressure in the delivery pipes 64 and 65 becomes higher than a predetermined pressure, the relief valve 95 is opened and high pressure fuel is discharged through the fuel discharge pipe 94 to the second chamber 82b in the fuel tank 81. Further, a part of the low-pressure fuel boosted by the feed pump 83 is returned from the low-pressure fuel supply pipe 84 to the first chamber 82a through the fuel return pipe 91, the jet pump 89, and the fuel transfer pipe 92. At this time, the jet pump 89 uses the negative pressure generated when the returned fuel passes through the venturi, and transfers the fuel remaining in the second chamber 82b to the first chamber 82a through the fuel transfer pipe 92.

  The high pressure fuel pump 85 described above will be described in detail. In the high-pressure fuel pump 85, as shown in FIG. 3-1, a plunger 102 is supported on the casing 101 so as to be movable up and down, and a pressure chamber 103 for boosting the fuel is formed. An upper portion of the casing 101 is formed with a suction port 104 that communicates with the low pressure fuel supply pipe 84 and sucks the low pressure fuel, and a discharge port 105 that discharges the pressurized high pressure fuel to the high pressure fuel supply pipe 86. Yes. In addition, a metering valve 106 for opening and closing the suction port 104 is provided at the upper portion of the casing 101. This metering valve 106 is an electromagnetic spill valve, and is biased in a direction to open the suction port 104 by a spring 107. The suction port 104 can be closed by energizing the electromagnetic solenoid 108 that is supported.

  In addition, a lifter 109 is connected to a lower end portion of the plunger 102, and a spring 111 is interposed between the lifter 109 and the cylinder head cover 110, and the plunger 102 is biased and supported through the lifter 109. Yes. On the other hand, a drive cam 112 having three cam peaks 112 a to 112 c is fixed to the outer peripheral portion of the intake camshaft 32, and this drive cam 112 is in contact with the lower surface of the lifter 109.

  Accordingly, as shown in FIG. 3A, the intake camshaft 32 moves in the direction of the arrow from the intake start position where the cam crest 112a of the drive cam 112 of the intake camshaft 32 contacts the lifter 109 and moves the plunger 102 upward. , The cam crest 112a moves away from the lifter 109, and the plunger 102 is lowered via the lifter 109 by the biasing force of the spring 111. At this time, the metering valve 106 opens the suction port 104 by the biasing force of the spring 107, and the low pressure fuel in the low pressure fuel supply pipe 84 can be sucked into the pressure chamber 103 through the suction port 104.

  When the drive cam 112 of the intake camshaft 32 rotates 60 degrees (120 CA) from the intake start position described above, the flat portion between the cam peaks 112a and 112b contacts the lifter 109 as shown in FIG. 3-2. Thus, the suction end position where the plunger 102 is most lowered, that is, the pumping start position is obtained. When the intake camshaft 32 rotates in the direction of the arrow from this pumping start position, the cam crest 112b moves so as to approach the lifter 109, so that the cam crest 112b resists the urging force of the spring 111 and lifts the lifter 109. The plunger 102 is raised. At this time, when the electromagnetic solenoid 108 is energized, the metering valve 106 closes the suction port 104 against the urging force of the spring 107, boosts the low-pressure fuel in the pressure chamber 103, and reaches a predetermined pressure. The pressurized high pressure fuel can be pumped from the discharge port 105 to the high pressure fuel supply pipe 86 through the check valve 88.

  Then, when the drive cam 112 of the intake camshaft 32 rotates 60 degrees (120 CA) from the above-described pumping start position, the cam peak 112b raises the plunger 102 most via the lifter 109, that is, the suction start. Position.

  By the way, in the engine of this embodiment, the high pressure fuel pump 85 reciprocates the plunger 102 by the drive cam 112 of the intake camshaft 32, so the ECU 70 detects the crank angle sensor 75 (or cam position sensor). The position of the plunger 102 is detected based on the signal, and the opening / closing timing of the electromagnetic spill valve is set in accordance with the detected position, thereby properly adjusting the fuel. However, in a relatively quiet operating state such as an idling operation of the engine, the operation sound accompanying the opening and closing of the electromagnetic spill valve becomes remarkable, and silence is hindered.

  Therefore, in this embodiment, when the engine is idling, after the warm-up is completed, the cooling water temperature becomes high, the fuel is relatively easy to vaporize and atomize, and the rotation speed is low, so the period from fuel injection to ignition Since the in-cylinder pressure is relatively long and the in-cylinder pressure is also relatively low, even when the low pressure fuel pressurized by the feed pump 83 is injected into the combustion chambers 22 and 23, the low pressure fuel can be sufficiently vaporized and atomized. . Therefore, during this idling operation, the electromagnetic spill valve is stopped at the open position, and the low-pressure fuel pressurized by the feed pump 83 bypasses the high-pressure fuel pump 85 and is pumped to the delivery pipes 64 and 65, and the injectors 62 and 63 Injects low-pressure fuel into the combustion chambers 22 and 23, thereby reducing the operating noise associated with the opening and closing of the electromagnetic spill valve in the high-pressure fuel pump 85.

  In this case, the pressure chamber 103 in the casing 101 is applied as a fuel passage through which the low-pressure fuel from the feed pump 83 passes without being pressurized by the high-pressure fuel pump 85. That is, when the metering valve 106 is maintained at the position where the suction port 104 is opened by the urging force of the spring 107 without energizing the electromagnetic solenoid 108 by the high pressure fuel pump 85, the low pressure fuel pressurized by the feed pump 83 is supplied. The low-pressure fuel supply pipe 84 passes through the pressure chamber 103 and is pumped to the high-pressure fuel supply pipe 86 at a low pressure.

  Further, the ECU 70 determines the fuel injection amount based on the engine operating state such as the intake air amount, the intake air temperature, the throttle opening, the accelerator opening, the engine speed, and the cooling water temperature. Further, the ECU 70 determines the fuel injection time based on the fuel injection amount and the fuel pressure in the delivery pipes 64 and 65. In this case, fuel pulsation occurs in the delivery pipes 64 and 65 due to the pressure increase by the high-pressure fuel pump 85 and the fuel injection by the injectors 62 and 63. Therefore, the ECU 70 calculates the fuel pressure average value by averaging the detection values of the fuel pressure sensor 78 in a predetermined fuel pressure setting time, and sets the fuel injection time using this fuel pressure average value.

  However, in this embodiment, since the operation and stop of the high-pressure fuel pump 85 are switched according to the operating state of the engine, the fuel pressure fluctuates greatly at the time of this switching. Then, a deviation (delay) occurs between the actual fuel pressure and the average fuel pressure value, and the actual fuel injection amount is too much or too little with respect to the required fuel injection amount. There is a risk of variation.

  Therefore, in the present embodiment, as shown in FIG. 1, when the ECU 70 as the fuel pressure control means switches the high pressure fuel pump 85 between the stopped state and the operating state, the ECU 70 as the fuel injection control means The fuel pressure setting time is changed to a predetermined value or less over a predetermined fuel pressure changing time set in advance from the time of switching of the pump 85. Specifically, when the ECU 70 switches the high-pressure fuel pump 85 between a stopped state and an operating state, the ECU 70 changes the fuel pressure detected by the fuel pressure sensor 78 over a predetermined fuel pressure change time from the time of switching the high-pressure fuel pump 85. Based on this, the fuel injection time by the injectors 62 and 63 is set.

  In this case, in this embodiment, when the ECU 70 switches the high-pressure fuel pump 85 from the operating state to the stopped state, a fuel correction coefficient is set based on the fuel pressure detected by the fuel pressure sensor 78, and the injector is used using this fuel correction coefficient. The fuel injection time by 62 and 63 is set, and the fuel injection amount is increased.

  Here, the operation stop control of the high-pressure fuel pump 85 by the ECU 70 will be described in detail based on the flowchart of FIG.

  In the operation control of the high pressure fuel pump 85 of the internal combustion engine of the present embodiment, as shown in FIG. 4, in step S11, the ECU 70 determines whether or not a condition for stopping the operation of the high pressure fuel pump 85 is satisfied. Here, the conditions for stopping the operation of the high-pressure fuel pump 85 are when the engine coolant temperature is equal to or higher than a predetermined value set in advance, the engine load is completed, and the engine load is equal to or lower than a predetermined value set in advance. It is. The engine load is a target engine speed, an actual engine speed, a fuel injection amount, an intake air amount, a vehicle speed, or the like, and may be a load factor. If it is determined in step S11 that the condition for stopping the operation of the high-pressure fuel pump 85 is satisfied, the operation of the high-pressure fuel pump 85 is stopped in step S12.

  Accordingly, as shown in FIGS. 1 and 3-1, the high-pressure fuel pump 85 is maintained at a position where the metering valve 106 opens the suction port 104 by the biasing force of the spring 107. Therefore, the low-pressure fuel pressurized by the feed pump 83 is not pressurized from the low-pressure fuel supply pipe 84 by the high-pressure fuel pump 85 but is pumped to the high-pressure fuel supply pipe 86 through the pressure chamber 103. The low-pressure fuel is pumped to delivery pipes 64 and 65 and injected into the combustion chambers 22 and 23 by injectors 62 and 63. In this case, the engine speed is low and the fuel injection amount is small. For example, if the engine is idling, the low pressure fuel pressurized by the feed pump 83 can be injected into the combustion chambers 22 and 23. In addition, low-pressure fuel can be vaporized and atomized. And since the electromagnetic spill valve in the high-pressure fuel pump 85 is stopped, the operation noise accompanying the opening and closing thereof is reduced.

  In step S13, the ECU 70 determines whether or not a predetermined fuel pressure change time set in advance has elapsed since the operation of the high-pressure fuel pump 85 was stopped. The fuel pressure change time is, for example, the time from when the operation of the high-pressure fuel pump 85 is stopped until the fuel pressure in the delivery pipes 64 and 65 decreases to a predetermined value and stabilizes. I ask for it.

  The fuel pressure change time is not limited to the time measured by the timer. For example, the fuel pressure detected by the fuel pressure sensor 78, the fuel pressure average value set based on the fuel pressure detected by the fuel pressure sensor 78, or the deviation between the fuel pressure and the fuel pressure average value may be used. That is, it is determined whether or not the fuel pressure has become equal to or lower than a predetermined fuel pressure after the operation of the high-pressure fuel pump 85 is stopped. Further, it is determined whether or not the fuel pressure average value has become equal to or lower than a predetermined fuel pressure average value set after the operation of the high-pressure fuel pump 85 is stopped. Further, it is determined whether or not the fuel pressure deviation has become equal to or smaller than a predetermined fuel pressure deviation after the operation of the high-pressure fuel pump 85 is stopped.

  If it is determined in step S13 that the fuel pressure change time has not elapsed since the operation of the high-pressure fuel pump 85 was stopped, in step S14, the ECU 70 changes the fuel pressure setting time to a predetermined value or less, that is, The fuel correction coefficient is calculated using the fuel pressure detected by the fuel pressure sensor 78 without using the average fuel pressure value calculated by averaging the detection values of the fuel pressure sensor 78.

  Specifically, as shown in FIG. 5, the fuel injection time by the injectors 62 and 63 is set with respect to the fuel injection amount, and this fuel injection time differs depending on the fuel pressure. Therefore, low-pressure fuel correction coefficients KinjAL and KinjBL used when the high-pressure fuel pump 85 is stopped and high-pressure fuel correction coefficients KinjAH and KinjBH used when the high-pressure fuel pump 85 is operating are set. In this embodiment, the low-pressure fuel correction coefficients (slopes) KinjAL and KinjBL and the high-pressure fuel correction coefficients (initial amounts) KinjAH and KinjBH are set based on the fuel pressure detected by the fuel pressure sensor 78.

  Then, returning to FIG. 4, in step S15, the fuel injection time by the injectors 62 and 63 is set using the following mathematical formula, and the fuel injection amount is increased. Note that TL is a fuel injection period when the high-pressure fuel pump 85 is stopped, TH is a fuel injection period when the high-pressure fuel pump 85 is operating, and K is a fuel injection period set according to the operating state. Amount.

TL = K × injAL + KinjBL
TH = K × injAH + KinjBH

  Therefore, when the high-pressure fuel pump 85 is switched from the operating state to the stopped state, the high-pressure fuel pump 85 does not boost the low-pressure fuel, so the fuel pressure in the delivery pipes 64 and 65 is the fuel injection of the injectors 62 and 63. The fuel pressure average value decreases with a delay from the actual fuel pressure. Therefore, at this time, if the fuel injection time of the injectors 62 and 63 is calculated using the fuel pressure average value, the fuel injection time is calculated using the fuel pressure higher than the actual fuel pressure. However, the amount of fuel is insufficient. On the other hand, when the fuel injection time of the injectors 62 and 63 is calculated using the detection value of the fuel pressure sensor 78 as in the present embodiment, the fuel injection time is calculated using the actual fuel pressure. However, the fuel amount is almost the same.

  If it is determined in step S13 that the fuel pressure change time has elapsed since the operation of the high-pressure fuel pump 85 was stopped, the injector 62, A fuel injection time of 63 is calculated. If it is determined in step S11 that the condition for stopping the operation of the high-pressure fuel pump 85 is not satisfied, this routine is exited without doing anything. That is, the operation of the high-pressure fuel pump 85 is continued and the fuel injection time of the injectors 62 and 63 is calculated using the fuel pressure average value.

  Accordingly, when the high-pressure fuel pump 85 is in operation, the high-pressure fuel pump 85 adjusts based on the fuel pressure in the delivery pipes 64 and 65 detected by the fuel pressure sensor 78, as shown in FIGS. The amount valve 106 is controlled to open and close. Therefore, the low-pressure fuel pressurized by the feed pump 83 is further pressurized by the high-pressure fuel pump 85 and is sent to the high-pressure fuel supply pipe 86 as high-pressure fuel. The high-pressure fuel is pumped to delivery pipes 64 and 65 and injected into the combustion chambers 22 and 23 by injectors 62 and 63. In this predetermined acceleration state, since the engine speed is high, the operating noise in the high-pressure fuel pump 85 does not become significant.

  As described above, in the fuel supply device for the internal combustion engine of the first embodiment, the feed pump (fuel pumping means) 83 pressurizes the fuel and pumps it as a low pressure fuel, and the high pressure that boosts the low pressure fuel and pumps it as a high pressure fuel. A fuel pump (pressure-increasing means) 85, a pressure chamber 103 as a fuel passage through which the low-pressure fuel from the feed pump 83 passes without being pressurized by the high-pressure fuel pump 85, and low-pressure fuel or high-pressure fuel is injected into the combustion chambers 22 and 23. Injectors (fuel injection means) 62, 63, fuel pressure control means for controlling the stop and operation of low pressure fuel by the high pressure fuel pump 85 according to the engine operating state, and the fuel pressure average value at a predetermined fuel pressure setting time. An ECU 70 constituting fuel injection control means for setting the fuel injection time by the injectors 62 and 63 is provided. When the high pressure fuel pump 85 is switched from the operating state to the stopped state, the ECU 70 determines the fuel injection time by the injectors 62 and 63 based on the fuel pressure detected by the fuel pressure sensor 78 over a predetermined fuel pressure change time from the switching time. Set.

  Therefore, when the high-pressure fuel pump 85 is switched from the operating state to the stopped state, the deviation between the actual fuel pressure and the average fuel pressure value increases, and therefore, based on the fuel pressure detected by the fuel pressure sensor 78 over a predetermined fuel pressure change time. Thus, by setting the fuel injection time by the injectors 62 and 63, the deviation of the fuel injection amount according to the fluctuation of the fuel pressure is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio is suppressed, Deterioration of emissions can be prevented.

  In the internal combustion engine fuel supply apparatus according to the first embodiment, when the high pressure fuel pump 85 is switched from the operating state to the stopped state, the ECU 70 increases the fuel pressure injection amount over a predetermined fuel pressure change time from when the high pressure fuel pump 85 is stopped. Like to do. When the fuel injection time of the injectors 62 and 63 is calculated using the average fuel pressure value, the fuel injection time is calculated using a fuel pressure higher than the actual fuel pressure. Run short. On the other hand, when the fuel injection time of the injectors 62 and 63 is calculated using the detected value of the fuel pressure sensor 78, the fuel injection time is calculated using the actual fuel pressure, so that the fuel that is substantially equivalent to the target fuel injection amount. It becomes quantity. Accordingly, by increasing the fuel pressure injection amount when the high-pressure fuel pump 85 is stopped, it is possible to ensure an appropriate fuel injection amount according to the engine operating state.

  6 is a flowchart showing the operation control of the fuel supply device for the internal combustion engine according to the second embodiment of the present invention, FIG. 7 is a graph showing the increase coefficient with respect to the fuel pressure value, and FIG. 8 is an increase coefficient with respect to the deviation of the fuel pressure value. It is a graph to represent. The overall configuration of the fuel supply device for the internal combustion engine of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and have the same functions as those described in this embodiment. The same reference numerals are given to the members, and duplicate descriptions are omitted.

  In the fuel supply apparatus for an internal combustion engine according to the second embodiment, as shown in FIG. 1, when the high pressure fuel pump 85 is switched from the operating state to the stopped state, the ECU 70 The fuel is increased over the fuel pressure change time.

  Here, the operation stop control of the high-pressure fuel pump 85 by the ECU 70 will be described in detail based on the flowchart of FIG.

  In the operation control of the high-pressure fuel pump 85 of the internal combustion engine of the present embodiment, as shown in FIG. 6, in step S21, the ECU 70 determines whether a condition for stopping the operation of the high-pressure fuel pump 85 is satisfied. If it is determined that the condition for stopping the operation of the high-pressure fuel pump 85 is satisfied, the operation of the high-pressure fuel pump 85 is stopped in step S22.

  In step S23, the ECU 70 determines whether or not a predetermined fuel pressure change time set in advance has elapsed since the operation of the high-pressure fuel pump 85 was stopped. If it is determined that the fuel pressure change time has not elapsed since the operation of the high-pressure fuel pump 85 is stopped, the ECU 70 changes the fuel pressure set time to a predetermined value or less in step S24, that is, the fuel pressure sensor 78. The fuel increase coefficient is calculated using the fuel pressure detected by.

  Specifically, as shown in the graph of FIG. 7, an increase coefficient in fuel injection with respect to the fuel pressure value is set in advance. In this case, the fuel pressure value is desirably the fuel pressure detected by the fuel pressure sensor 78, but may be an average fuel pressure value calculated by averaging the detection values of the fuel pressure sensor 78. Further, as shown in the graph of FIG. 8, an increase coefficient in fuel injection with respect to the deviation between the fuel pressure value and the fuel pressure average value may be set in advance. When the increase coefficient is set based on the fuel pressure value (or the deviation of the fuel pressure value), the fuel injection amount is increased in step S25, and the injectors 62, 63 are set in accordance with the increased fuel injection amount. The fuel injection time is set.

  Therefore, when the high-pressure fuel pump 85 is switched from the operating state to the stopped state, the fuel increase value is set based on the fuel pressure value or the deviation of the fuel pressure value, so that the fuel amount substantially equal to the target fuel injection amount is set. can do.

  If it is determined in step S23 that the fuel pressure change time has elapsed since the operation of the high-pressure fuel pump 85 was stopped, the injector 62, A fuel injection time of 63 is calculated. If it is determined in step S21 that the condition for stopping the operation of the high-pressure fuel pump 85 is not satisfied, this routine is exited without doing anything. That is, the operation of the high-pressure fuel pump 85 is continued and the fuel injection time of the injectors 62 and 63 is calculated using the fuel pressure average value.

  As described above, in the fuel supply device for an internal combustion engine according to the second embodiment, when the high-pressure fuel pump 85 is switched from the operating state to the stopped state, the ECU 70 performs the fuel pressure value or the fuel pressure over the predetermined fuel pressure change time from the switching time. An increase coefficient is set based on the deviation of the values, and fuel injection times by the injectors 62 and 63 are set based on the increased fuel injection amount.

  Accordingly, when the high-pressure fuel pump 85 is switched from the operating state to the stopped state, the deviation between the actual fuel pressure and the average fuel pressure value increases, so that the fuel pressure is increased by increasing the fuel over a predetermined fuel pressure change time. The deviation of the fuel injection amount corresponding to the fluctuation is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio can be suppressed, and the deterioration of combustion and emission can be prevented.

  FIG. 9 is a flowchart showing the operation control of the fuel supply device for the internal combustion engine according to the third embodiment of the present invention, and FIG. 10 is a graph showing a change in fuel pressure at the start of operation of the high-pressure fuel pump. The overall configuration of the fuel supply device for the internal combustion engine of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and have the same functions as those described in this embodiment. The same reference numerals are given to the members, and duplicate descriptions are omitted.

  In the fuel supply apparatus for an internal combustion engine according to the third embodiment, as shown in FIG. 1, when the high pressure fuel pump 85 is switched from the stopped state to the operating state, the ECU 70 The fuel injection time by the injectors 62 and 63 is set using the fuel pressure detected by the fuel pressure sensor 78 without using the fuel pressure average value over the fuel pressure change time.

  Here, the operation stop control of the high-pressure fuel pump 85 by the ECU 70 will be described in detail based on the flowchart of FIG.

  In the operation control of the high-pressure fuel pump 85 of the internal combustion engine of the present embodiment, as shown in FIG. 9, in step S31, the ECU 70 determines whether a condition for stopping the operation of the high-pressure fuel pump 85 is satisfied. Here, if it is determined that the condition for stopping the operation of the high-pressure fuel pump 85 is satisfied, the operation of the high-pressure fuel pump 85 is stopped in step S32.

  On the other hand, if it is determined in step S31 that the condition for stopping the operation of the high-pressure fuel pump 85 is not satisfied, the operation of the high-pressure fuel pump 85 is resumed in step S33. In step S34, the ECU 70 determines whether or not an elapsed time since the operation of the high-pressure fuel pump 85 is resumed is within a predetermined fuel pressure change time set in advance. This fuel pressure change time is, for example, the time from when the operation of the high-pressure fuel pump 85 is restarted until the fuel pressure in the delivery pipes 64 and 65 rises to a predetermined value and stabilizes. I ask for it.

  The fuel pressure change time is not limited to the time measured by the timer. For example, the fuel pressure detected by the fuel pressure sensor 78, the fuel pressure average value set based on the fuel pressure detected by the fuel pressure sensor 78, or the deviation between the fuel pressure and the fuel pressure average value may be used. That is, it is determined whether or not the fuel pressure is within a predetermined fuel pressure set after the operation of the high-pressure fuel pump 85 is restarted. Further, it is determined whether or not the fuel pressure average value is within a predetermined predetermined fuel pressure average value after the operation of the high-pressure fuel pump 85 is restarted. Further, it is determined whether or not the fuel pressure deviation is equal to or greater than a predetermined fuel pressure deviation that has been set in advance after the operation of the high-pressure fuel pump 85 is resumed. Furthermore, the number of injections of the injectors 62 and 63 may be used, and it may be determined whether the number of fuel injections after restarting the operation of the high-pressure fuel pump 85 is within a predetermined number of fuel injections set in advance.

  If it is determined in step S34 that the elapsed time since the operation of the high-pressure fuel pump 85 is resumed is within the fuel pressure change time, the ECU 70 changes the fuel pressure setting time to a predetermined value or less in step S35. That is, the fuel correction coefficient is calculated using the fuel pressure detected by the fuel pressure sensor 78 without using the average fuel pressure value calculated by averaging the detection values of the fuel pressure sensor 78. Specifically, as in the first embodiment described above, the low pressure fuel correction coefficient (slope) and the high pressure fuel correction coefficient (initial amount) are set based on the fuel pressure detected by the fuel pressure sensor 78. In step S36, the fuel injection time by the injectors 62 and 63 is set using the low pressure fuel correction coefficient and the high pressure fuel correction coefficient set based on the fuel pressure, and the fuel injection amount is reduced.

  Therefore, as shown in FIG. 10, when the high-pressure fuel pump 85 is switched from the stopped (OFF) state to the operating state (ON), the high-pressure fuel pump 85 starts to pressurize and pump low-pressure fuel. The fuel pressure in 64 and 65 rises. However, it temporarily decreases due to fuel injection from the injectors 62 and 63. On the other hand, the fuel pressure average value rises with a delay from the actual fuel pressure, and a maximum deviation ΔP occurs between the fuel pressure and the fuel pressure average value at the first fuel injection. Therefore, at this time, if the fuel injection time of the injectors 62 and 63 is calculated using the fuel pressure average value, the fuel injection time is calculated using the fuel pressure lower than the actual fuel pressure, and therefore the target fuel injection amount However, the amount of fuel becomes excessive. On the other hand, when the fuel injection time of the injectors 62 and 63 is calculated using the detection value of the fuel pressure sensor 78 as in the present embodiment, the fuel injection time is calculated using the actual fuel pressure. However, the fuel amount is almost the same.

  If it is determined in step S34 that the elapsed time since the operation of the high-pressure fuel pump 85 has stopped exceeds the fuel pressure change time, the average value of the fuel pressure is determined while the operation of the high-pressure fuel pump 85 is resumed. Using this, the fuel injection time of the injectors 62 and 63 is calculated.

  As described above, in the fuel supply device for an internal combustion engine according to the third embodiment, when the ECU 70 switches the high-pressure fuel pump 85 from the stopped state to the operating state, the fuel pressure sensor 78 is detected over a predetermined fuel pressure change time from the switching time. The fuel injection time by the injectors 62 and 63 is set based on the detected fuel pressure.

  Accordingly, when the high-pressure fuel pump 85 is switched from the stopped state to the operating state, the deviation between the actual fuel pressure and the average fuel pressure value increases, and therefore, based on the fuel pressure detected by the fuel pressure sensor 78 over a predetermined fuel pressure change time. Thus, by setting the fuel injection time by the injectors 62 and 63, the deviation of the fuel injection amount according to the fluctuation of the fuel pressure is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio is suppressed, Deterioration of emissions can be prevented.

  In the internal combustion engine fuel supply apparatus according to the third embodiment, when the high pressure fuel pump 85 is switched from the stopped state to the operating state, the ECU 70 reduces the fuel pressure injection amount over a predetermined fuel pressure change time from when the high pressure fuel pump 85 is stopped. Like to do. When the fuel injection time of the injectors 62 and 63 is calculated using the average fuel pressure value, the fuel injection time is calculated using a fuel pressure lower than the actual fuel pressure. It becomes excessive. On the other hand, when the fuel injection time of the injectors 62 and 63 is calculated using the detected value of the fuel pressure sensor 78, the fuel injection time is calculated using the actual fuel pressure, so that the fuel that is substantially equivalent to the target fuel injection amount. It becomes quantity. Therefore, by reducing the fuel pressure injection amount when the high-pressure fuel pump 85 is restarted, it is possible to ensure an appropriate fuel injection amount according to the engine operating state.

  FIG. 11 is a flowchart showing the operation control of the fuel supply device for the internal combustion engine according to the fourth embodiment of the present invention, and FIG. 12 is a graph showing the increase coefficient with respect to the elapsed time. The overall configuration of the fuel supply device for the internal combustion engine of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and have the same functions as those described in this embodiment. The same reference numerals are given to the members, and duplicate descriptions are omitted.

  In the fuel supply device for an internal combustion engine according to the fourth embodiment, as shown in FIG. 1, when the high pressure fuel pump 85 is switched from the stopped state to the operating state, the ECU 70 has a predetermined value set in advance from when the high pressure fuel pump 85 is switched. The fuel is reduced over the fuel pressure change time.

  Here, the operation stop control of the high-pressure fuel pump 85 by the ECU 70 will be described in detail based on the flowchart of FIG.

  In the operation control of the high-pressure fuel pump 85 of the internal combustion engine of the present embodiment, as shown in FIG. 11, in step S41, the ECU 70 determines whether a condition for stopping the operation of the high-pressure fuel pump 85 is satisfied. If it is determined that the condition for stopping the operation of the high-pressure fuel pump 85 is satisfied, the operation of the high-pressure fuel pump 85 is stopped in step S42.

  On the other hand, if it is determined in step S41 that the condition for stopping the operation of the high-pressure fuel pump 85 is not satisfied, the operation of the high-pressure fuel pump 85 is resumed in step S43. In step S44, the ECU 70 determines whether or not an elapsed time since the operation of the high-pressure fuel pump 85 is restarted is within a predetermined fuel pressure change time set in advance. Here, if it is determined that the elapsed time since the operation of the high-pressure fuel pump 85 is restarted is within the fuel pressure change time, in step S55, the ECU 70 changes the fuel pressure setting time to a predetermined value or less, that is, the fuel pressure. The fuel increase coefficient is calculated using the fuel pressure detected by the sensor 78 and gradually increased.

  Specifically, an increase coefficient in fuel injection with respect to the fuel pressure value is set in advance. In this case, the fuel pressure value is preferably the fuel pressure detected by the fuel pressure sensor 78, but as a deviation between the fuel pressure average value calculated by averaging the detection values of the fuel pressure sensor 78, the fuel pressure value, and the fuel pressure average value. Also good. In this case, the fuel increase coefficient is smaller than 1.0, and the fuel is decreased. Then, as shown in FIG. 12, the fuel increase coefficient is increased so as to approach 1.0 with the passage of time. When the increase coefficient is set based on the fuel pressure value (or deviation of the fuel pressure value) and the increase amount is set, the fuel injection amount is decreased in step S56, and the fuel injection amount is reduced according to the decreased fuel injection amount. Thus, the fuel injection time of the injectors 62 and 63 is set. In this case, since the increase coefficient is increased with time, the decrease in the fuel injection amount is reduced, and the fuel injection time of the injectors 62 and 63 is changed.

  Therefore, when the high-pressure fuel pump 85 is switched from the stopped state to the operating state, the increase coefficient is set based on the fuel pressure value or the deviation of the fuel pressure value, and the fuel consumption is gradually increased. On the other hand, approximately the same fuel amount can be set.

  If it is determined in step S44 that the elapsed time since the operation of the high-pressure fuel pump 85 has stopped exceeds the fuel pressure change time, the average value of the fuel pressure is determined while the operation of the high-pressure fuel pump 85 is resumed. Using this, the fuel injection time of the injectors 62 and 63 is calculated.

  As described above, in the fuel supply device for an internal combustion engine according to the fourth embodiment, when the ECU 70 switches the high-pressure fuel pump 85 from the stopped state to the operating state, the fuel pressure value or the fuel pressure is maintained over a predetermined fuel pressure change time from the switching time. An increase coefficient is set based on the value deviation, and the fuel injection time by the injectors 62 and 63 is set based on the reduced fuel injection amount.

  Accordingly, when the high-pressure fuel pump 85 is switched from the stopped state to the operating state, the deviation between the actual fuel pressure and the average fuel pressure value becomes large. Therefore, the fuel pressure is reduced by reducing the fuel over a predetermined fuel pressure change time. The deviation of the fuel injection amount corresponding to the fluctuation is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio can be suppressed, and the deterioration of combustion and emission can be prevented.

  Further, in the fuel supply device for an internal combustion engine according to the fourth embodiment, when the high pressure fuel pump 85 is switched from the stopped state to the operating state, the ECU 70 increases the set increase coefficient so as to gradually approach 1.0. Accordingly, a deviation between the actual fuel pressure and the average fuel pressure value occurs with the resumption of the high-pressure fuel pump 85. Since this deviation decreases with the passage of time, the increase coefficient should be changed accordingly. Thus, it is possible to appropriately suppress the deviation of the fuel injection amount according to the fluctuation of the fuel pressure.

  FIG. 14 is a flowchart showing the operation control of the fuel supply device for the internal combustion engine according to the fifth embodiment of the present invention, and FIG. 15 is a graph showing the increase coefficient with respect to the number of injections after the high-pressure fuel pump is restarted. The overall configuration of the fuel supply device for the internal combustion engine of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to the drawings and members having the same functions as those described in the present embodiment. Are denoted by the same reference numerals, and redundant description is omitted.

  In the fuel supply apparatus for an internal combustion engine according to the fifth embodiment, as shown in FIG. 1, when the high pressure fuel pump 85 is switched from the stopped state to the operating state, the ECU 70 During the fuel pressure change time, the amount of fuel is reduced and the amount of reduction is set to be smaller in the order of the fuel injection cylinders.

  Here, the operation stop control of the high-pressure fuel pump 85 by the ECU 70 will be described in detail based on the flowchart of FIG.

  In the operation control of the high-pressure fuel pump 85 of the internal combustion engine of the present embodiment, as shown in FIG. 13, in step S51, the ECU 70 determines whether a condition for stopping the operation of the high-pressure fuel pump 85 is satisfied. If it is determined that the condition for stopping the operation of the high-pressure fuel pump 85 is satisfied, the operation of the high-pressure fuel pump 85 is stopped in step S52.

  On the other hand, if it is determined in step S51 that the condition for stopping the operation of the high-pressure fuel pump 85 is not satisfied, the operation of the high-pressure fuel pump 85 is resumed in step S53. In step S54, the ECU 70 determines whether the number of injections after restarting the operation of the high-pressure fuel pump 85 is within a predetermined number of injections set in advance. Here, if it is determined that the number of injections after restarting the operation of the high-pressure fuel pump 85 is within the predetermined number of injections, in step S55, the ECU 70 uses the fuel pressure detected by the fuel pressure sensor 78 to fuel the fuel. An increase coefficient is calculated for each number of injections.

  Specifically, an increase coefficient in fuel injection with respect to the fuel pressure value is set in advance, but in this embodiment, the fuel increase coefficient is smaller than 1.0, and the fuel is reduced. This fuel increase coefficient is set according to the number of injections after the high-pressure fuel pump 85 is restarted, as shown in FIG. That is, the fuel pressure average value rises with a delay from the actual fuel pressure, and during the first fuel injection, the deviation between the fuel pressure and the fuel pressure average value becomes maximum and gradually decreases. Therefore, the increase coefficient of the first injection cylinder after restarting the high-pressure fuel pump 85 is set to be the smallest (decreasing the increase), and the increase coefficient of the cylinders in the subsequent injection order is increased so as to gradually approach 1.0 ( Set so that the weight loss is small. Further, each increase coefficient is increased (decrease is reduced) so as to approach 1.0 with the passage of time. When the increase coefficient is set based on the fuel pressure value (or the deviation of the fuel pressure value), the fuel injection amount is decreased in step S56, and the injectors 62, 63 are operated in accordance with the decreased fuel injection amount. The fuel injection time is set.

  Therefore, when the high-pressure fuel pump 85 is switched from the stopped state to the operating state, the increase coefficient is set based on the fuel pressure value or the deviation of the fuel pressure value, and the fuel consumption is gradually increased. On the other hand, approximately the same fuel amount can be set.

  If it is determined in step S54 that the number of injections after the operation of the high-pressure fuel pump 85 has stopped exceeds a predetermined number of injections, the fuel pressure average value is maintained while the operation of the high-pressure fuel pump 85 is resumed. Is used to calculate the fuel injection time of the injectors 62 and 63.

  Thus, in the fuel supply device for the internal combustion engine of the fifth embodiment, when the ECU 70 switches the high-pressure fuel pump 85 from the stopped state to the operating state, the fuel pressure value or the fuel pressure over the predetermined fuel pressure change time from the switching time. An increase coefficient is set for each injection cylinder based on the value deviation, and the fuel injection time by the injectors 62 and 63 is set based on the reduced fuel injection amount.

  Accordingly, when the high-pressure fuel pump 85 is switched from the stopped state to the operating state, the deviation between the actual fuel pressure and the average fuel pressure value becomes large. Therefore, the fuel pressure is reduced by reducing the fuel over a predetermined fuel pressure change time. The deviation of the fuel injection amount corresponding to the fluctuation is suppressed, and by ensuring the appropriate fuel amount, the variation in the air-fuel ratio can be suppressed, and the deterioration of combustion and emission can be prevented. At this time, since the increase coefficient is set for each injection cylinder, an appropriate fuel injection amount can be ensured in accordance with the variation in deviation between the actual fuel pressure and the average fuel pressure value.

  In each of the above-described embodiments, the fuel control is individually described when the high-pressure fuel pump 85 is switched from the operating state to the stopped state or when the high-pressure fuel pump 85 is switched from the stopped state to the operating state. These may be carried out synchronously.

  The internal combustion engine of the present invention can be applied to all fuel systems that supply fuel to engines that are internal combustion engines such as gasoline engines and diesel engines mounted on vehicles such as passenger cars and trucks. The engine form is not limited to the V-type 6-cylinder engine, but may be an in-line 4-cylinder engine, and the number of cylinders is not limited to each embodiment.

  As described above, the fuel supply device for an internal combustion engine according to the present invention can suppress variation in the air-fuel ratio by ensuring an appropriate amount of fuel in accordance with fluctuations in fuel pressure, and can prevent deterioration of combustion and emissions. The booster is useful for driving the internal combustion engine according to the operating state of the internal combustion engine, and is particularly suitable for reducing the influence of the pulsation generated from the booster on the fuel system of the internal combustion engine.

1 is a schematic configuration diagram illustrating a fuel system in a fuel supply device for an internal combustion engine according to Embodiment 1 of the present invention. 1 is a longitudinal sectional view of a main part of an internal combustion engine according to a first embodiment. 1 is a schematic diagram illustrating a high-pressure fuel pump in a fuel supply device for an internal combustion engine according to a first embodiment. 1 is a schematic diagram illustrating a high-pressure fuel pump in a fuel supply device for an internal combustion engine according to a first embodiment. 3 is a flowchart illustrating operation control of the fuel supply device for the internal combustion engine according to the first embodiment. It is a graph showing the injection time with respect to fuel injection quantity and fuel pressure. It is a flowchart showing the operation control of the fuel supply apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a graph showing the increase coefficient with respect to a fuel pressure value. It is a graph showing the increase coefficient with respect to the deviation of a fuel pressure value. It is a flowchart showing the operation | movement control of the fuel supply apparatus of the internal combustion engine which concerns on Example 3 of this invention. It is a graph showing the change of the fuel pressure at the time of the driving | operation start of a high pressure fuel pump. It is a flowchart showing the operation control of the fuel supply apparatus of the internal combustion engine which concerns on Example 4 of this invention. It is a graph showing the increase coefficient with respect to elapsed time. It is a flowchart showing the operation | movement control of the fuel supply apparatus of the internal combustion engine which concerns on Example 5 of this invention. It is a graph showing the increase coefficient with respect to the frequency | count of injection after resumption of a high pressure fuel pump.

Explanation of symbols

22, 23 Combustion chamber 62, 63 Injector (fuel injection means)
64, 65 Delivery pipe 66, 67 Spark plug 70 Electronic control unit, ECU (fuel pressure control means, fuel injection control means)
78 Fuel pressure sensor 83 Feed pump (Fuel pressure feeding means)
85 High-pressure fuel pump (pressure booster)
103 Pressure chamber (fuel passage)

Claims (6)

Fuel pumping means for pressurizing the fuel and pumping it as low-pressure fuel;
Pressurizing means for boosting the low pressure fuel pumped by the fuel pumping means and pumping it as high pressure fuel;
A fuel passage through which the low-pressure fuel from the fuel pumping means passes without being boosted by the boosting means;
Fuel injection means for injecting low pressure fuel or high pressure fuel into the combustion chamber;
Fuel pressure control means for controlling stop and operation of boosting of the low-pressure fuel by the boosting means according to the operating state of the internal combustion engine;
Fuel injection control means for setting a fuel injection time by the fuel injection means based on a fuel pressure average value at a predetermined fuel pressure setting time;
An internal combustion engine fuel supply apparatus comprising:
When the fuel pressure control means switches the boosting means between a stopped state and an operating state, the fuel injection control means sets a fuel pressure setting time over a predetermined fuel pressure change time set in advance from the switching of the boosting means. Change to below the specified value,
A fuel supply device for an internal combustion engine.   A fuel pressure sensor for detecting the pressure of fuel supplied to the fuel injection means is provided, and when the fuel pressure control means switches the pressure increase means between a stopped state and an operating state, the fuel injection control means 2. The internal combustion engine according to claim 1, wherein the fuel injection time by the fuel injection means is set based on the fuel pressure detected by the fuel pressure sensor over a preset fuel pressure change time from the time of switching of the pressure increasing means. Fuel supply system.   When the fuel pressure control means switches the boosting means between a stopped state and an operating state, the fuel injection control means is based on the fuel pressure detected by the fuel pressure sensor or the fuel pressure detected by the fuel pressure sensor. 3. The fuel supply device for an internal combustion engine according to claim 2, wherein the fuel pressure change time is set based on the fuel pressure average value set in the above or a deviation between the fuel pressure and the fuel pressure average value.   When the fuel pressure control means switches the boosting means from the operating state to the stopped state, the fuel injection control means increases the fuel pressure injection amount over a predetermined fuel pressure change time set in advance from when the boosting means is stopped. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3.   When the boosting means is switched from the stopped state to the operating state by the fuel pressure control means, the fuel injection control means reduces the fuel injection amount over a predetermined fuel pressure change time set in advance from when the boosting means is operated. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3.   6. The fuel injection control unit according to claim 5, wherein the fuel injection control unit decreases the fuel injection amount over a predetermined fuel pressure change time set in advance from the time of operation of the boosting unit, and sets the decrease in order of the fuel injection cylinder. A fuel supply device for an internal combustion engine as described.

Images