JP2013231362A - Fuel pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pressure control device configured to prevent a relief valve which regulates a set upper-limit fuel pressure from being repeatedly opened/closed during fuel stop in an internal combustion engine, to improve reliability of the relief valve.SOLUTION: A fuel pressure control device includes: a feed pump for supplying fuel to an engine which can temporarily shift from a fuel consumption operating state to a fuel cut state; a relief valve which limits supply pressure of the fuel supplied from the pump to the engine at a preset upper-limit pressure or lower; and a fuel pressure varying mechanism for variably controlling the supply pressure of the fuel according to an operation state of the engine. The fuel pressure varying mechanism controls a discharge pressure Pd of a fuel pump in the fuel cut state at a higher pressure than the set upper-limit pressure Pr (step S14) on condition that the supply pressure of the fuel increases in an increasing tendency that may reach the set upper-limit pressure Pr after the engine enters the fuel cut state (YES in step S12).

Description

  The present invention relates to a fuel pressure control device, and more particularly to a fuel pressure control device capable of controlling a fuel supply pressure of an internal combustion engine.

  Recently, in an internal combustion engine mounted on a vehicle, the fuel injection amount has been reduced from a very small amount so as to minimize exhaust emission while responding to the required operation input from the driver, and to meet advanced fuel consumption reduction requirements. It is required to control accurately in a wide injection amount range up to a large amount. Therefore, a fuel pressure control device has been proposed that variably controls the pressure of fuel supplied to the internal combustion engine (hereinafter, this fuel pressure is also simply referred to as fuel pressure) on demand according to a requested operation input from a driver.

  As such a fuel pressure control device, for example, in a fuel cut state in which fuel injection by the fuel injection valve is temporarily stopped during operation of the internal combustion engine, when the pressure in the fuel pipe on the fuel injection valve side becomes high, An electromagnetic relief valve for opening and closing a relief pipe that returns the fuel in the fuel pipe to the fuel tank is opened to return the fuel in the fuel pipe into the fuel tank (for example, Patent Document 1). In this device, it is possible to prevent the fuel pressure in the fuel pipe on the fuel injection valve side from becoming excessively high, and to prevent fuel leakage from the fuel injection valve.

  In addition, the set fuel pressures of the first and second pressure regulators arranged on the upstream side and the return side of the fuel injection valve are made different, and the set fuel pressure of the second pressure regulator arranged on the return side is changed to the first There is known one that sets a pressure higher than the pressure obtained by adding the pulsation of the fuel supply pressure to the set fuel pressure of the pressure regulator (see, for example, Patent Document 2). In this device, it is possible to prevent the reliability of the pressure regulator from being lowered due to an increase in the number of operations of the pressure regulator due to the pulsation of the fuel supply pressure.

  Furthermore, a relief valve capable of adjusting the fuel pressure supplied to the fuel injection valve is attached to the relief valve mounting hole that communicates with the delivery pipe through the communication hole, and a throttle is provided downstream from the relief valve. There is also known one in which the center line of the seat pipe protruding from the seat body to the upstream side and the center line of the communication hole are eccentric (see, for example, Patent Document 3). In this device, the pulsation pressure is hardly transmitted directly to the relief valve, and an extra opening / closing operation of the relief valve due to the pulsation pressure is suppressed by the downstream throttle.

JP 2010-071132 A JP 07-189873 A JP 2000-145569 A

  However, in the conventional fuel pressure control device as described above, a relief valve or a pressure regulator (hereinafter, the fuel pressure is limited to a set fuel pressure or less) due to the pulsation component of the supply fuel pressure when the fuel is stopped by fuel cut control or the like of the internal combustion engine. There is a problem that durability of the relief valve and vibration / noise performance of the relief valve are liable to be lowered due to frequent opening / closing operations of the relief valve.

  In other words, when the flow of fuel in the fuel supply path from the feed pump to the fuel injection valve stops by shifting to the fuel stop state due to fuel cut or the like, the fuel in the closed fuel supply path receives heat from the internal combustion engine via the piping. As a result, the temperature and pressure of the fuel rise. When the fuel pressure reaches the relief valve opening set pressure, a part of the fuel is returned to the fuel tank through the relief valve, so that the fuel pressure in the fuel supply path is equal to the relief valve opening preset pressure. The pressure in the vicinity is maintained. In such a state, the fuel pressure in the fuel supply path fluctuates up and down the valve opening set pressure due to the pulsation component, and the relief valve frequently repeats opening and closing operations, thereby improving the durability of the relief valve. And vibration / noise performance was degraded.

  On the other hand, automatic stop control such as fuel cut control and idling stop has been widely spread because it greatly contributes to improvement of fuel consumption of a vehicle equipped with an internal combustion engine. Therefore, as described above, it has been an important solution to prevent the reliability of the fuel supply system from being lowered due to the decrease in durability and vibration / noise performance of the relief valve.

  Accordingly, the present invention provides a fuel pressure control device capable of sufficiently improving the reliability of the relief valve by suppressing the relief valve that defines the set upper limit fuel pressure from repeatedly opening and closing when the fuel of the internal combustion engine is stopped. Is to provide.

  In order to solve the above-described problems, a fuel pressure control device according to the present invention provides (1) a fuel consumption that can be shifted from a fuel consumption state that operates while consuming fuel to a fuel stop state that temporarily stops the fuel consumption. A fuel pump that supplies the fuel to the fuel supply unit, a relief valve that limits a supply pressure of the fuel supplied from the fuel pump to the fuel consumption unit to a preset upper limit pressure, and a fuel consumption unit A fuel pressure control mechanism that variably controls the supply pressure in accordance with an operating state, wherein the fuel pressure variable mechanism is configured such that the supply pressure is changed after the fuel consumption unit has shifted to the fuel stop state. The discharge pressure of the fuel pump under the fuel stop condition is controlled to a pressure different from the set upper limit pressure on the condition that the fuel pump rises with an increasing tendency to reach the set upper limit pressure. To.

  Therefore, after the fuel consumption part has shifted to the fuel stop state, when the fuel pressure supplied to the fuel consumption part under the fuel stop state rises due to a temperature rise caused by the fuel stop, etc. The discharge pressure from the fuel pump is controlled to a pressure different from the set upper limit pressure by the fuel pressure variable mechanism. As a result, when the supply fuel pressure in the fuel stop state approaches the set upper limit pressure, the discharge pressure of the fuel pump is controlled to a pressure different from the set upper limit pressure by the fuel pressure variable mechanism, so that the relief valve is opened or It will be in the state energized to the valve closing side, and it will be controlled effectively that a relief valve repeats opening and closing operation.

  In the fuel pressure control device according to the present invention, (2) the fuel pressure variable mechanism is configured such that the set upper limit pressure is within a fluctuation range of the supply pressure after the fuel consuming unit shifts to the fuel stop state. As a condition, it is preferable to control the discharge pressure of the fuel pump to a pressure different from the set upper limit pressure. In this case, it is possible to accurately suppress the supply fuel pressure to the fuel consumption unit from changing across the set upper limit pressure.

  In the fuel pressure control device according to the present invention, (3) the fuel pressure variable mechanism may be configured such that when the supply pressure in the fuel stop state reaches the set upper limit pressure, the discharge pressure of the fuel pump is set higher than the set upper limit pressure. It is preferable to control to a high pressure. In this case, when the supply pressure reaches the set upper limit pressure, the discharge pressure of the fuel pump is immediately changed, and unnecessary opening and closing of the relief valve can be reliably suppressed. Further, it is only necessary to increase the discharge pressure of the fuel pump, and control becomes easy.

  In the fuel pressure control device according to the present invention, (4) the fuel pressure variable mechanism sets the discharge pressure of the fuel pump to the set upper limit pressure on the condition that the set upper limit pressure is within the fluctuation range of the supply pressure. The pressure may be controlled to a lower pressure. Also in this case, when the supply pressure reaches the set upper limit pressure, the discharge pressure of the fuel pump is immediately changed, and the unnecessary opening and closing of the relief valve can be reliably suppressed. In addition to changing the discharge pressure of the fuel pump, the supply pressure of the fuel supplied from the fuel pump to the fuel consuming part can be controlled quickly and accurately to a pressure lower than the set upper limit pressure not only by changing the discharge pressure of the fuel pump. Thus, the relief valve can be biased to the valve opening side or the valve closing side. Further, it is only necessary to lower the discharge pressure of the fuel pump, and control becomes easy.

  In the fuel pressure control device of the present invention, (5) the fuel pressure variable mechanism is configured such that when the supply pressure in the fuel stop state reaches the set upper limit pressure, the discharge pressure of the fuel pump is set from the set upper limit pressure. It is good to control to a low pressure. In this case, when the supply pressure reaches the set upper limit pressure, the discharge pressure of the fuel pump is immediately changed, and unnecessary opening and closing of the relief valve can be reliably suppressed. Further, it is only necessary to lower the discharge pressure of the fuel pump, and control becomes easy.

  In the fuel pressure control apparatus of the present invention, (6) the fuel consuming unit is an internal combustion engine that consumes fuel while injecting fuel with the fuel injection valve, and the supply pressure is the fuel supplied to the fuel injection valve. When the internal combustion engine is in the fuel consumption state, the fuel pressure variable mechanism variably controls the supply pressure within a fuel pressure control range below the set upper limit pressure, while in the fuel stop state. When the set upper limit pressure is within the fluctuation range of the supply pressure, it is preferable to control the discharge pressure of the fuel pump to a pressure higher than the fuel pressure control range.

  In this case, by combining the variable control of the supply pressure and the control of the fuel injection time, the fuel injection amount can be accurately controlled over a wide injection amount range from a minute amount to a large amount, and the fuel pressure is excessive. Can be prevented.

  In the fuel pressure control device of the present invention, (7) a first operating state where the valve is opened at a low pressure setting pressure lower than the set upper limit pressure, and a valve which is not opened even when the supply pressure reaches the low pressure setting pressure or higher. A reduction valve that can be switched between two operating states and that can reduce the supply pressure to the low pressure setting pressure when the valve is opened may be provided.

  In this case, the driving load of the fuel pump can be sufficiently reduced by increasing the amount of excess fuel discharged when the reduction valve is opened.

  According to the present invention, when the fuel pressure supplied to the fuel consuming unit rises in a rising tendency that can reach the set upper limit pressure while the fuel consuming unit is in the fuel stopped state, the discharge pressure of the fuel pump is set to the set upper limit pressure by the variable fuel pressure mechanism. Since the pressure is controlled at different pressures, the relief valve can be urged toward the valve opening side or the valve closing side when the fuel is stopped to suppress repeated opening and closing operations, and the reliability of the relief valve can be sufficiently improved. A fuel pressure control device can be provided.

It is a schematic block diagram of the fuel supply system provided with the fuel pressure control apparatus which concerns on 1st Embodiment of this invention. It is a principal part block diagram which shows the structure of the fuel pump vicinity of the fuel supply system provided with the fuel pressure control apparatus which concerns on 1st Embodiment of this invention. It is a block block diagram of the control system of the fuel supply system provided with the fuel pressure control apparatus which concerns on 1st Embodiment of this invention. It is a schematic flowchart which shows the switching control procedure of the feed fuel pressure performed in the fuel stop state of the fuel supply system provided with the fuel pressure control apparatus which concerns on 1st Embodiment of this invention. It is a timing chart which shows change of feed fuel pressure and feed pump load before and after transfer to a fuel stop state of a fuel supply system provided with a fuel pressure control device concerning a 1st embodiment of the present invention. It is operation | movement explanatory drawing of the fuel pressure control apparatus which concerns on 1st Embodiment of this invention. It is a principal part block diagram which shows the structure of the fuel pump vicinity of the fuel supply system provided with the fuel pressure control apparatus which concerns on 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1 to 6 show a first embodiment of a fuel pressure control device according to the present invention.

  In this embodiment, the present invention is applied to a fuel supply system for an internal combustion engine that drives and drives a vehicle.

  First, the configuration of the fuel supply system will be described.

  As shown in FIG. 1, the fuel supply system of the present embodiment includes a first fuel supply mechanism 20 that supplies low-pressure side fuel for port injection to an engine 10 (fuel consumption unit) that is a multi-cylinder internal combustion engine, A second fuel supply mechanism 30 that pressurizes the fuel supplied from the first fuel supply mechanism 20 to supply high-pressure side fuel for in-cylinder injection, and variably controls the supply pressure of low-pressure side fuel according to the operating state of the engine 10 And a variable fuel pressure mechanism 40.

  The engine 10 is a multi-cylinder internal combustion engine mounted on an automobile, for example, an in-line 4-cylinder 4-cycle gasoline engine. The engine 10 normally operates in a fuel consumption state in which rotational power is output from a crankshaft (not shown) while consuming fuel, for example, gasoline, in the combustion chamber 13 in each cylinder 11. Further, the engine 10 can be operated in a fuel cut state (fuel stop state) in which the crankshaft is rotated without consuming fuel temporarily under a specific vehicle operation state such as deceleration or engine braking. ing. Each cylinder 11 accommodates a piston 12, defines a combustion chamber 13, and is mounted so that an intake valve 14 and an exhaust valve (not shown) are opened and closed at predetermined timings. Further, the engine 10 is provided with a plurality of spark plugs 15 corresponding to the plurality of cylinders 11 so as to be exposed in the corresponding combustion chambers 13, and an ignition coil having an ignition coil for igniting the spark plugs 15 is provided. A device 16 (see FIG. 3) and an electronically controlled throttle motor 17 that variably controls the throttle opening are provided.

  The first fuel supply mechanism 20 includes a fuel tank 21, a feed pump 22 (fuel pump), a relief valve 23, a reduction valve 24, a first fuel pipe 25 (low pressure fuel pipe), a low pressure side delivery pipe 26, and a plurality of ports. An injector 27 (fuel injection valve) for injection, a fuel pressure control circuit 28 and a jet pump 29 are included.

  The fuel tank 21 has, for example, a predetermined volume containing the sub tank 21a, and can be replenished with fuel from the outside. The fuel tank 21 may be a vertical type or the like that is divided into a plurality of tank portions corresponding to the inside and the outside of the sub tank according to the shape of the bottom wall.

  The feed pump 22 is of a variable discharge capacity (discharge amount and discharge pressure) type that can pump up the fuel in the fuel tank 21 and pressurize it to a predetermined feed fuel pressure or higher, and is constituted by a circumferential flow pump, for example. . The feed pump 22 includes a pump operating impeller and a built-in motor that drives the pump operating portion. For example, the pump operating impeller according to the drive voltage and load torque of the built-in motor. By changing at least one of the rotation speed and the rotation torque, the discharge capacity per unit time, that is, the discharge pressure and the discharge amount can be changed. The feed pump 22 is provided with a coupling filter 22f in which a suction filter portion that captures foreign matter in the intake fuel and a fuel filter portion that captures foreign matter in the discharged fuel are coupled.

  The relief valve 23 opens when the pressure of the fuel discharged from the feed pump 22 into the first fuel pipe 25 rises to reach a preset upper limit pressure, and the fuel pressure is equal to or lower than the preset upper limit pressure. It is a pressure control valve having a safety valve function to limit to. The set upper limit pressure referred to here is a fuel pressure that is high enough to easily induce fuel leakage from the port injection injector 27 when the fuel pressure exceeds the set upper limit pressure. This certain set upper limit fuel pressure is set to 600 kPa, for example.

  As shown in FIG. 2, the relief valve 23 includes, for example, a relief valve body 23a for closing a fuel discharge port (not shown in detail) from the first fuel pipe 25 side, and the relief valve body 23a is normally closed. The relief valve 23 itself can be any conventional relief valve structure that can be used to limit fuel pressure.

  The reduction valve 24 is an electromagnetic that can be switched between a valve-open state in which fuel from the first fuel pipe 25 can be discharged into the sub-tank 21a of the fuel tank 21 through the throttle 24a and a valve-closed state in which fuel discharge is prevented. It is excited when the amount of fuel consumption is small, such as when the engine 10 is idling, so that surplus fuel can be returned to the fuel tank 21.

  The weight reducing valve 24 includes a valve body 24v including at least a part of a magnetic material, and a holding cylinder portion that holds the valve body 24v in a movable state in the axial direction and introduces fuel from the first fuel pipe 25 side. 24b, a throttle 24a provided on the fuel discharge port side of the holding cylinder part 24b, and a coil 24c supported by the holding cylinder part 24b and capable of urging the valve body 24v away from the throttle 24a. ing. In addition, the holding cylinder portion 24b is formed with a valve seat (not shown) that is seated when the valve body 24v moves to the throttle 24a side, and the fuel discharge on the throttle 24a side when the valve body 24v sits on the valve seat. When the outlet is closed and the valve body 24v is disengaged from the valve seat, the fuel discharge port on the throttle 24a side is opened. Further, when the valve body 24v is urged by the coil 24c in a direction to detach from the valve seat, the valve body 24v does not close the fuel introduction port on the first fuel pipe 25 side of the holding cylinder portion 24b. It can be pressed against 24b.

  In the ON state in which the coil 24c is excited, the reduction valve 24 has a low pressure setting pressure that is sufficiently lower than the set upper limit pressure as the valve body 24v is detached from the valve seat on the throttle 24a side. Even in this case, the first operating state is opened. On the other hand, in the OFF state where the coil 24c is not excited, the reduction valve 24 is urged in the direction in which the valve body 24v is seated on the valve seat on the throttle 24a side by the fuel pressure from the first fuel pipe 25 side. Even when the fuel pressure is equal to or higher than the low set pressure, for example, the set upper limit pressure, the second operating state is set in which the valve is not opened.

  The delivery pipe 26 on the low-pressure side is made of metal that introduces fuel pressurized by the feed pump 22 through the first fuel pipe 25 and stores a predetermined amount of fuel, and bends according to the pressure of the fuel. Thus, both the function of absorbing the pulsation of the fuel pressure and the function of accumulating the fuel pressure necessary for port injection from the port injection injector 27 are provided.

  The plurality of port injection injectors 27 are provided corresponding to the plurality of cylinders 11 of the engine 10, and end portions on the injection hole side are exposed in the intake ports 11 a corresponding to the cylinders 11. . The injectors 27 are connected to the low pressure delivery pipe 26 and wired to a driver circuit 51 on the ECU 50 side so as to be opened by a port injection drive signal from the ECU 50. When the plurality of injectors 27 are sequentially driven by the port injection drive signal, the fuel accumulated and stored in the delivery pipe 26 on the low pressure side from some of the opened injectors 27 is port injection driven. The fuel is injected into the corresponding intake port 11a in accordance with the valve opening time ratio (duty ratio) for each predetermined time by the signal.

  A fuel pressure control circuit (referred to as FPC in FIG. 1) 28 controls the drive voltage of the feed pump 22 in accordance with the required fuel pressure Pc from the ECU 50, whereby the discharge capacity (discharge amount and discharge pressure) of the feed pump 22 is controlled. The fuel pressure in the delivery pipe 26 on the low pressure side can be made to follow the required fuel pressure Pc from the ECU 50. The required fuel pressure Pc from the ECU 50 is calculated by the ECU 50 based on the operation state of the vehicle and the engine 10 and the required operation input from the driver. This point will be described later.

  The jet pump 29 discharges the fuel from the first fuel pipe 25 into the sub tank 21a of the fuel tank 21 through an internal venturi (not shown). The jet pump 29 in the fuel tank 21 has a venturi effect corresponding to the discharge flow rate. Thus, the fuel stored outside the sub tank 21a is pumped into the sub tank 21a. The jet pump 29 serves as a means for introducing fuel into the sub tank 21 a by the amount of fuel consumed successively by the engine 10.

  The second fuel supply mechanism 30 includes a plunger-type fuel pressurizing pump 31, an electromagnetic spill-type intake control valve 32, a second fuel pipe 35, a high-pressure side delivery pipe 36, and a plurality of in-cylinder injectors. 37 (high pressure fuel injection valve).

  The fuel pressurization pump 31 sucks the fuel pressurized by the feed pump 22 into the fuel pressurization chamber through the second fuel pipe 35 by changing the volume of the fuel pressurization chamber by reciprocating a plunger (not shown). At the same time, the sucked fuel is pressurized while the suction control valve 32 is closed, and can be discharged at a high pressure that allows direct in-cylinder fuel injection.

  The suction control valve 32 is selectively excited to enable the fuel pressurization operation of the fuel pressurization pump 31 and opens during the volume increase period of the fuel pressurization chamber of the fuel pressurization pump 31. During the volume reduction period of the fuel pressurization chamber of the pressure pump 31, the valve can be closed only for a necessary period corresponding to the discharge amount (discharge fuel flow rate). Further, the suction control valve 32 can keep its open state so that the fuel pressurizing operation of the fuel pressurizing pump 31 is disabled.

  The delivery pipe 36 on the high pressure side is made of a highly rigid metal that introduces and stores fuel pressurized to high pressure by the fuel pressurizing pump 31, and has a function of accumulating fuel pressure necessary for direct fuel injection in the cylinder. Have.

  The plurality of in-cylinder injectors 37 are each connected to a high-pressure delivery pipe 36 and wired to a driver circuit 51 on the ECU 50 side so as to be opened by an in-cylinder injection drive signal from the ECU 50. The high-pressure fuel accumulated and stored in the delivery pipe 36 on the high-pressure side at the time of the valve opening is stored in the corresponding cylinder 11 according to the valve opening time ratio (duty ratio) for each predetermined time by the in-cylinder injection drive signal. It comes to inject.

  The fuel pressurizing pump 31 is driven by rotational power from a crankshaft (not shown) of the engine 10. Further, the electromagnetic spill type suction control valve 32 is always opened when the power is not supplied.

  The variable fuel pressure mechanism 40 includes a feed pump 22 and a fuel pressure control circuit 28 of the first fuel supply mechanism 20, and an ECU 50 that variably controls the discharge capacity of the feed pump 22 via the fuel pressure control circuit 28. A function of variably controlling the discharge capacity of the feed pump 22 based on the operating state of the engine 10 and the requested operation input from the driver is exhibited.

  The ECU 50 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a backup memory (for example, a nonvolatile memory or a RAM backed up by a battery). The input interface circuit and the output interface circuit are included.

  The input interface circuit of the ECU 50 receives an ON / OFF signal of an ignition switch of the vehicle via an ignition relay switch 60 (see FIG. 3), and sensor information from various sensor groups includes an A / D converter and the like. It is captured through the input interface circuit. The output interface circuit of the ECU 50 is connected to the injectors 27 and 37 for port injection and in-cylinder injection and the electromagnetic drive unit (not shown) of the intake control valve 32 via the driver circuit 51, and also controls the fuel pressure. A circuit 28, an electronic throttle motor, the ignition device described above, and the like are connected.

  The various sensor groups connected to the input interface circuit of the ECU 50 include, for example, an accelerator opening sensor 61, an air flow meter 62, a crank angle sensor 63, a water temperature sensor 64, and a low-pressure fuel pressure sensor 65. Sensor 66, throttle opening sensor 67, air-fuel ratio sensor 68, oxygen sensor 69, intake cam angle sensor 71, exhaust cam angle sensor 72, high pressure fuel pressure sensor 73, and the like may be included. Here, the accelerator opening sensor 61 detects the depression rate of an accelerator pedal (not shown) mounted on the vehicle as the accelerator opening (Accp in FIG. 1), and the air flow meter 62 detects the intake air amount (see FIG. Qa) in 1 is detected. The crank angle sensor 63 detects a crank angle (CA in FIG. 1) from which the engine rotation speed of the engine 10 can be calculated, and the water temperature sensor 64 detects the coolant temperature (Thw in FIG. 1) of the engine 10. . The fuel pressure sensor 65 detects the fuel pressure (Pf in FIG. 1) in the delivery pipe 26 on the low pressure side.

  The ECU 50 can execute known electronic throttle control, fuel injection amount control, ignition timing control, fuel cut control, and the like by executing a control program stored in the ROM. For example, the ECU 50 calculates the basic injection amount required for each combustion based on the intake air amount detected by the air flow meter and the engine speed detected by the crank angle sensor, and further according to the operating state of the engine 10. Further, the fuel injection amount subjected to various corrections, air-fuel ratio feedback correction, and the like can be calculated, and the injectors 27 and 37 corresponding to the fuel injection time corresponding to the fuel injection amount can be driven to open.

  Further, the ECU 50 sets a target fuel pressure according to the operating state of the engine 10, for example, at a high temperature restart when the engine 10 is started in a state where the cooling water temperature of the engine 10 is higher than a predetermined temperature, or fuel The target fuel pressure is set to a high fuel pressure, for example, 530 kPa, when returning from the cut state to the normal operation state where the fuel is consumed.

  When the engine 10 is restarted from a so-called idling stop state in which the engine 10 is automatically stopped when the vehicle is temporarily stopped, for example, when the engine is restarted at a high temperature, the power unit is a vehicle equipped with a hybrid traveling drive unit. For example, when the engine 10 is temporarily stopped and then restarted. The fuel cut state refers to an in-cylinder injector in a predetermined operating state of the engine 10, for example, when the accelerator opening is substantially zero when the vehicle is decelerated or downhill, and the engine 10 is in a crank rotation state. 37 and the fuel injection from the port injector 27 are temporarily stopped, and while the ECU 50 determines that the fuel cut is possible based on various sensor information, the fuel cut is performed. It is supposed to be executed.

  By the way, when the engine 10 is in the idling stop state, the cooling of the engine 10 by the cooling water or the cooling air is stopped, so that the temperature of the fuel in the fuel supply path such as the delivery pipe 26 on the low-pressure side increases. Since the saturated vapor pressure of the fuel that depends on the fuel pressure increases, fuel vapor is likely to occur. Even in the fuel cut state, the fuel flow is stopped in the fuel supply path such as the delivery pipe 26 and the low temperature fuel from the fuel tank 21 side is not introduced. It becomes higher, the saturated vapor pressure of the fuel depending on the temperature becomes higher, and fuel vapor tends to be generated. When fuel vapor is generated in the fuel in the fuel supply path, for example, normal fuel pressurization by the fuel pressurization pump 31 cannot be performed due to so-called air engagement, and the exhaust emission of the engine 10 deteriorates or the engine 10 The driving condition may be worsened. Therefore, in the present embodiment, when the saturated vapor pressure of the fuel becomes high, the ECU 50 sets a high fuel pressure target fuel pressure (for example, pulsation median value of 530 kPa) to suppress the generation of fuel vapor. .

  The high fuel pressure target fuel pressure here corresponds to a fuel pressure at which the upper limit fuel pressure due to the pulsation does not exceed the set upper limit fuel pressure even when the pulsation increases under the setting state of the high fuel pressure target fuel pressure. The target fuel pressure of the high fuel pressure is used to ensure a necessary fuel supply pressure or to control the fuel injection amount when the engine 10 is restarted at a high temperature, when returning from a fuel cut state for a long time, or during high load operation. This is a fuel pressure that can bias the dynamic range of the fuel to the high fuel consumption side.

  On the other hand, for example, when the engine 10 is in a mode region where the engine 10 is exclusively in partial load operation, the target fuel pressure on the low pressure side where fuel vapor does not easily occur in the fuel supply path due to heat generation of the engine 10 in the mode region, for example, 300 kPa is set.

  The target fuel pressure on the low pressure side is, for example, a fuel pressure at which the lower limit fuel pressure due to the pulsation does not fall below the saturated vapor pressure even when the pulsation of the feed fuel pressure occurs, and the operation period of the mode region This is a fuel pressure that can suppress the power consumption of the feed pump in the interior and can bias the dynamic range of the fuel injection amount control toward the low fuel consumption amount side. Note that the drive voltage of the feed pump 22 when the target fuel pressure on the low pressure side is set is such that even if foreign matter passing through the coupling filter 22f is sucked into the feed pump 22, the feed pump 22 pump Sufficient rotational torque can be generated to such an extent that the impeller for operation is not locked.

  The ECU 50 responds to the target fuel pressure according to the operating state of the engine 10, the acceleration request from the driver, the shift operation or other requested operation input, etc. at predetermined time intervals during the operation period of the engine 10 or under the ignition ON state. The set pressure value is output to the fuel pressure control circuit 28 as the required fuel pressure Pc. Therefore, the required fuel pressure Pc output from the ECU 50 to the fuel pressure control circuit 28 is based on the operation state of the vehicle and the engine 10, the required operation input from the driver, and the like as described above.

  The fuel pressure control circuit 28 that inputs the requested fuel pressure Pc from the ECU 50 adjusts the deviation between these fuel pressures so that the inputted requested fuel pressure Pc matches the actual fuel pressure in the delivery pipe 26 detected by the fuel pressure sensor 65. Accordingly, the drive voltage of the feed pump 22 is controlled. Then, according to the change in the drive voltage from the fuel pressure control circuit 28, the rotational speed and rotational torque (of course, both speed and torque may be sufficient) of the impeller for operating the pump of the feed pump 22 change. As a result, the fuel pressure in the delivery pipe 26 on the low pressure side changes in a direction to follow the required fuel pressure Pc.

  On the other hand, the ECU 50 of the fuel pressure variable mechanism 40 executes a predetermined control program stored in the ROM, and as described above, based on the operation state of the vehicle and the engine 10, the requested operation input from the driver, and the like. The function of variably controlling the discharge capacity of the feed pump 22 is exhibited. However, after the engine 10 shifts to the fuel cut state, the feed fuel pressure (supply pressure) rises with an increasing tendency to reach the above-mentioned set upper limit pressure. By controlling the discharge pressure of the feed pump 22 in the fuel stop state to a pressure different from the set upper limit pressure, the feed fuel pressure is controlled to a fuel pressure deviating from the above set upper limit pressure (hereinafter also referred to as bias set fuel pressure). It is like that.

  Here, the rising tendency that can reach the set upper limit pressure is, for example, a fuel pressure change tendency such that the feed fuel pressure at a certain time elapses with respect to the feed fuel pressure at the time of transition to the fuel cut state, the pulsation center fuel pressure The fuel pressure change tendency such that the average fuel pressure per fixed time rises continuously after shifting to the fuel cut state, or the fuel pressure change that the fuel pressure increase rate after shifting to the fuel cut state exceeds the predetermined value Trends.

  Then, for example, the ECU 50 determines whether or not the transition occurs depending on whether or not a significant increase in fuel pressure that is equal to or greater than a predetermined determination threshold occurs with respect to the fuel pressure at the transition time after a certain period of time after the engine 10 transitions to the fuel cut state. It is determined whether or not the fuel pressure in the fuel supply path under the fuel cut state tends to increase to such an extent that it can reach the set upper limit pressure that is the valve opening set pressure of the relief valve 23. The significant increase in the fuel pressure above the determination threshold here means that the feed fuel pressure in the closed fuel supply path from the feed pump 22 to the port injector 27 after the engine 10 shifts to the fuel cut state is the relief valve 23. This means that the fuel rises with a rising tendency that can reach the set upper limit pressure that is the valve opening set pressure of the engine, and this fuel rise exclusively shifts the engine 10 to the fuel cut state, and the first fuel pipe 25 and the low pressure side This is because the fuel whose flow has stopped in the delivery pipe 26 rises in temperature due to heat received from the engine 10 through these pipes.

  Further, when the ECU 50 determines that the engine 10 is in a fuel cut state and a significant increase in fuel pressure that is equal to or greater than a predetermined determination threshold value has occurred in the feed fuel pressure, the discharge pressure of the feed pump 22 is set to the amount of fuel pressure pulsation. Even if the fuel pressure drop is taken into consideration, the pressure Pi is set higher than the set upper limit pressure, and the required fuel pressure Pc corresponding to the fuel pressure Pi is output to the fuel pressure control circuit 28. The fuel pressure control circuit 28 executes drive control to keep the discharge pressure of the feed pump 22 at a pressure Pi higher than the set upper limit pressure, so that the relief valve 23 under the fuel cut state of the engine 10 is always attached to the valve opening side. It has become possible to get the power.

  Alternatively, when the ECU 50 determines that the engine 10 is in a fuel cut state and a significant fuel pressure increase that is equal to or greater than a predetermined determination threshold value is set for the feed fuel pressure, the discharge pressure of the feed pump 22 is set to the fuel pressure pulsation amount. Even if the increase is taken into consideration, the pressure may be set lower than the above-described set upper limit pressure, and the required fuel pressure Pc corresponding to the fuel pressure may be output to the fuel pressure control circuit 28. In this case, the fuel pressure control circuit 28 keeps the discharge pressure of the feed pump 22 at a fuel pressure lower than the set upper limit pressure, so that the relief valve 23 can be normally urged to the closed side under the fuel cut state of the engine 10. When the feed fuel pressure from the feed pump 22 to the injector 27 for port injection is controlled to a fuel pressure lower than the above-mentioned set upper limit pressure, the discharge capacity of the feed pump 22 is not variably controlled, but another electromagnetic pressure reducing valve is used. A relief valve or the like can also be used. In that case, other electromagnetic pressure reducing valves, relief valves, and the like are components of the variable fuel pressure mechanism 40.

  As described above, when the engine 10 is not in the fuel cut state but in the fuel consumption state, for example, the engine 10 is in the mode range when the cooling water temperature of the engine 10 is higher than a predetermined temperature. When in the operation state, the feed fuel pressure is variably controlled within a fuel pressure control range (here, a fuel pressure range of 300 kPa to 530 kPa) equal to or lower than the above-described set upper limit pressure. During such operation, the valve closed state is maintained exclusively.

  Further, the ECU 50 repeatedly determines the load state during operation of the engine 10 based on sensor information from various sensor groups and set values or map information stored in advance in a ROM or backup memory (hereinafter referred to as ROM or the like). In the operation state in the mode range, the target fuel pressure is set to the feed fuel pressure on the low pressure side or a fuel pressure close thereto. On the other hand, when the engine 10 is restarted at a high temperature or returned from the fuel cut state, immediately before the engine 10 is stopped, the target fuel pressure is set to a feed fuel pressure on the high pressure side or a fuel pressure close thereto. Therefore, the set values stored in the ROM or the like of the ECU 50 include at least the set values of the high-pressure side feed fuel pressure and the low-pressure side feed fuel pressure that define the fuel pressure control range by the variable fuel pressure mechanism 40, and are stored in the ROM or the like. The map information includes a map for determining the operating load and controlling the fuel pressure according to the determination result.

  Further, the fuel pressure control circuit 28 is provided with a voltage detection unit that detects the terminal voltage of the built-in motor of the feed pump 22 and a current detection unit that detects the current flowing through the built-in motor of the feed pump 22. The fuel pressure control circuit 28 controls the voltage applied to the built-in motor of the feed pump 22 according to the deviation between the required fuel pressure Pc from the ECU 50 and the actual fuel pressure detected by the fuel pressure sensor 65, or for abnormality diagnosis. A diagnostic signal (Diag signal in FIG. 1) corresponding to the operating state of the built-in motor of the feed pump 22 can be supplied to the ECU 50. The fuel pressure control circuit 28 is supplied with power from a battery, and an ECU 50 is communicably connected thereto. Further, the fuel pressure control circuit 28 includes a switching element (not shown) for variably controlling the voltage applied to the built-in motor of the feed pump 22 or the energy supplied to the built-in motor of the feed pump 22.

  Next, the operation will be described.

  In the present embodiment configured as described above, the engine 10 operates in a fuel consumption state in which rotational power is output while consuming fuel in the combustion chamber 13 in each cylinder 11, or during deceleration or While it is determined by the ECU 50 that the fuel can be cut under a specific vehicle driving state such as when the engine is braked, it operates in a fuel cut state (fuel stop state) in which the crankshaft is rotated without consuming fuel.

  In the fuel consumption state of the engine 10, the discharge capability of the feed pump 22 is variably controlled by the fuel pressure variable mechanism 40 based on the operation state of the vehicle and the engine 10, the requested operation input from the driver, and the like, and supplied to the engine 10. The feed fuel pressure of the fuel is variably controlled within a fuel pressure control range lower than the set upper limit pressure Pr.

  If the feed fuel pressure is in the upper region I where the fuel pressure is higher than the saturated vapor pressure line A shown in FIG. 6 or the fuel temperature is lower, the generation of fuel vapor is suppressed. Therefore, the normal fuel pressure control by the variable fuel pressure mechanism 40 enters the region II below the saturated vapor pressure line A in the figure even if the pulsation component of the fuel pressure (illustrated by a waveform in the figure) is taken into consideration. Control is performed based on the operating state of the engine 10 and the detected fuel pressure of the fuel pressure sensor 65. For example, when the operating state of the engine 10 is in the mode range, the feed fuel pressure P1 on the low pressure side is set as the target fuel pressure, and when the engine 10 is restarted at a high temperature, when returning from the fuel cut state, or during high load operation For example, the feed fuel pressure P2 on the high pressure side is set as the target fuel pressure.

  On the other hand, under the fuel cut state of the engine 10, as shown in FIG. 5, the fuel pressure variable mechanism 40 changes the discharge pressure Pd of the feed pump 22 from the set upper limit pressure Pr to at least one side of fuel pressure pulsation (1/2 of the amplitude). The pressure Pi is controlled so as to deviate by the pressure fluctuation.

  Specifically, when the ignition switch is turned on, the ECU 50 executes feed pump drive voltage switching control as shown in FIG.

  As shown in the figure, in this feed pump drive voltage switching control, it is first determined whether or not a fuel cut is in progress (step S11). At this time, if it is not in the fuel cut state (NO in step S11), whether or not the fuel is being cut is repeatedly checked at a predetermined cycle until the fuel cut state is entered (step S11).

  Here, when the ECU 50 enters an operation state in which the fuel can be cut and enters the fuel cut state (in the case of YES in step S11), the process proceeds to the next step, and whether or not a significant increase in fuel pressure has occurred that is equal to or greater than the above-described fuel pressure increase determination threshold Is determined (step S12). That is, in this determination step, after the engine 10 shifts to the fuel cut state, the fuel pressure in the fuel supply path under the fuel cut state of the shift depends on whether or not a significant increase in the fuel pressure exceeds the determination threshold. It is determined whether the pressure has risen to such an extent that it can reach the set upper limit pressure, which is the valve opening set pressure of 23.

  At this time, if it is not determined that a significant increase in fuel pressure above the determination threshold has occurred (NO in step S12), then the feed fuel pressure is variable within the fuel pressure control range below the set upper limit pressure by the fuel pressure variable mechanism 40. By controlling and generating the required fuel pressure Pc with the normal required fuel pressure value, the discharge pressure of the feed pump 22 is controlled within the normal fuel pressure range (step S13).

  In such a fuel cut start stage, as shown in FIG. 5, the load of the feed pump 22 is once reduced.

  When the temperature of the fuel that has stopped flowing in the first fuel pipe 25 and the delivery pipe 26 on the low-pressure side due to the start of fuel cut rises due to heat received from the engine 10 via these pipes, the fuel pressure rise threshold is exceeded. In the determination of whether or not a significant increase in fuel pressure has occurred (step S12), it is determined that a significant increase in fuel pressure has occurred that is greater than or equal to the determination threshold (in the case of YES in step S12).

  In this case, the drive voltage corresponding to the discharge capacity of the feed pump 22 is then increased by the fuel pressure variable mechanism 40 (the feed pump load is increased) as shown in FIG. The discharge pressure Pd of the feed pump 22 is controlled to a pressure different from the set upper limit pressure, for example, a pressure Pi higher than the set upper limit pressure Pr. Therefore, the relief valve 23 that opens at the set upper limit pressure Pr is urged to the valve opening side by the discharge pressure Pd of the feed pump 22 at a pressure Pi higher than the set upper limit pressure Pr. As a result, the frequent opening / closing operation of the relief valve 23 due to the pulsation of the feed fuel pressure as shown by the broken line Pa in FIG. 5 is effectively suppressed.

  When the setting of the discharge pressure Pd of the feed pump 22 in such a fuel cut state (step S13 or S14) is completed, it is then determined whether or not the ignition switch is turned off (step S15). If the ignition switch is not in an OFF state (NO in step S15), a series of processes from steps S11 to S14 are repeated. On the other hand, if the ignition switch is in an OFF state (YES in step S15), this time This process ends.

  As described above, in the present embodiment, the fuel cut state is obtained on the condition that the feed fuel pressure rises with the increasing tendency that the fuel pressure variable mechanism 40 can reach the set upper limit pressure Pr after the engine 10 shifts to the fuel cut state. The discharge pressure Pd of the lower feed pump 22 is controlled to a pressure Pi different from the set upper limit pressure Pr. Therefore, in the low pressure fuel supply path after shifting to the fuel cut state, if the fuel pressure rises with an increasing tendency that can reach the set upper limit pressure Pr due to temperature rise or the like caused by fuel stop, the discharge pressure Pd of the feed pump 22 becomes the fuel pressure. By controlling the pressure Pi different from the set upper limit pressure Pr by the variable mechanism 40, the relief valve 23 is biased to the valve opening side or the valve closing side. As a result, the conventional problem that the relief valve 23 frequently repeats opening and closing operations under the fuel cut state is solved.

  In the present embodiment, the determination in step S12 by the ECU 50 of the fuel pressure variable mechanism 40 determines whether or not the set upper limit pressure Pr is within the fluctuation range of the feed fuel pressure after the engine 10 is shifted to the fuel cut state. The discharge pressure Pd of the feed pump 22 is controlled to a pressure Pi different from the set upper limit pressure Pr on condition that the set upper limit pressure Pr is within the fluctuation range of the feed fuel pressure. Therefore, it is possible to accurately suppress the fuel pressure supplied to the engine 10 from changing over the set upper limit pressure Pr.

  Further, when the feed fuel pressure under the fuel cut state reaches the set upper limit pressure Pr, if the discharge pressure of the feed pump 22 is controlled to a pressure Pi higher than the set upper limit pressure Pr, the feed fuel pressure becomes the set upper limit pressure Pr. As soon as it reaches, the discharge pressure of the feed pump 22 is changed, and unnecessary opening and closing of the relief valve 23 can be reliably suppressed. Further, it is only necessary to increase the discharge pressure of the feed pump 22, and the control can be easily performed by the existing fuel pressure control circuit.

  Further, even when the discharge pressure of the feed pump 22 is controlled to a pressure Pi lower than the set upper limit pressure Pr on condition that the set upper limit pressure Pr is within the fluctuation range of the feed fuel pressure, the feed fuel pressure becomes the set upper limit pressure Pr. As soon as it reaches, the discharge pressure of the feed pump 22 is changed, and the unnecessary opening and closing of the relief valve 23 can be reliably suppressed. Moreover, not only the discharge pressure of the feed pump 22 is changed, but also the pressure Pi that is lower than the set upper limit pressure Pr is quickly and accurately determined by other pressure reducing valves or the like. Thus, the relief valve 23 can be biased to the valve opening side or the valve closing side. Moreover, it is only necessary to lower the discharge pressure of the feed pump 22, and the control can be easily performed by the existing fuel pressure control circuit.

  In addition, in the present embodiment, the fuel pressure variable mechanism 40 variably controls the feed fuel pressure in the fuel consumption state of the engine 10 within a predetermined fuel pressure control range equal to or lower than the set upper limit pressure Pr, while in the fuel cut state. When the pressure Pr enters the fluctuation range of the feed fuel pressure, the discharge pressure of the feed pump 22 is controlled to a pressure Pi higher than the fuel pressure control range. Therefore, by combining the variable control of the feed fuel pressure and the control of the fuel injection time, the fuel injection amount can be accurately controlled in a wide dynamic range from a minute amount to a large amount, and the fuel pressure is excessively increased. This can be reliably prevented by the relief valve 23.

  Further, in the present embodiment, the first operation state is opened even when the feed fuel pressure is lower than the set upper limit pressure Pr, and the second operation state is not opened even when the feed fuel pressure exceeds the low pressure set pressure. The switchable reduction valve 24 can increase the discharge amount of surplus fuel when the valve is opened to reduce the supply fuel amount, thereby sufficiently reducing the load on the feed pump 22.

  As described above, according to the fuel pressure control device of the present embodiment, when the fuel pressure in the low-pressure fuel supply path rises with an increasing tendency that can reach the set upper limit pressure Pr under the fuel cut state of the engine 10, the feed pump 22 The discharge pressure Pd is controlled by the fuel pressure variable mechanism 40 to a pressure Pi different from the set upper limit pressure Pr. Therefore, under the fuel cut state, the relief valve 23 is urged toward the valve opening side or the valve closing side to suppress repeated opening / closing operations, and the reliability of the relief valve 23 can be sufficiently improved.

(Second Embodiment)
FIG. 7 is a diagram showing a second embodiment of the fuel pressure control apparatus according to the present invention.

  This embodiment has an overall configuration substantially similar to that of the first embodiment described above, and is different only in part. Therefore, only the components different from the first embodiment are illustrated in FIG. 7, and the common components are denoted by the reference numerals of the corresponding components illustrated in FIGS. explain.

  In the present embodiment, a throttle element 91 that is a fixed orifice is provided in the surplus fuel discharge path of the fuel discharged from the feed pump 22 in place of the reduction valve 24 in the first embodiment.

  The drive voltage of the feed pump 22 controlled by the fuel pressure control circuit 28 is such that, even if foreign matter passing through the coupling filter 22f is sucked into the feed pump 22, the impeller for operating the pump of the feed pump 22 is Although it is set so that a sufficient rotational torque can be generated so as not to be locked, the discharge capacity of the feed pump 22 (in consideration of the discharge amount of surplus fuel through the throttle element 91 into the fuel tank 21) Discharge pressure and discharge amount) are controlled. That is, since the throttle element 91 is a fixed orifice, the feed pump is considered in consideration of an increase in surplus fuel when the fuel consumption of the engine 10 increases as compared with the first embodiment in which the reduction valve 24 is additionally provided. 22 discharge capacity (discharge pressure and discharge amount) is controlled.

  Also in the present embodiment, when the fuel pressure in the low pressure fuel supply path rises with an increasing tendency that can reach the set upper limit pressure Pr under the fuel cut state of the engine 10, the discharge pressure Pd of the feed pump 22 is set by the fuel pressure variable mechanism 40. The pressure Pi is controlled to be different from the upper limit pressure Pr. Therefore, as in the case of the first embodiment described above, the relief valve 23 is urged toward the valve opening side or the valve closing side under the fuel cut state to suppress the repeated opening / closing operation, and thus the reliability of the relief valve 23 is improved. Can be sufficiently improved.

  In each of the above-described embodiments, depending on whether or not a significant increase in fuel pressure that is equal to or greater than a predetermined determination threshold with respect to the fuel pressure at the time of transition occurs after a certain period of time after the engine 10 transitions to the fuel cut state. It is determined whether or not the fuel pressure in the fuel supply path under the fuel cut state of the transition tends to increase to such an extent that it can reach the set upper limit pressure that is the valve opening set pressure of the relief valve 23. It may be determined that a significant increase in fuel pressure has occurred when the feed fuel pressure has increased beyond the fluctuation range of the pulsating component (only on the rising side) after the start of fuel cut. Alternatively, it may be determined that a significant increase in fuel pressure has occurred when the pulsation center value of the fuel pressure has risen above a predetermined pressure value. That is, if a substantial increase in fuel pressure excluding the pulsating component is detected under the fuel cut state, the fuel pressure changes with an increasing tendency that the feed fuel pressure can reach the set upper limit pressure Pr after the engine 10 shifts to the fuel cut state. It may be determined that In this case, it is not necessary to delay the fuel pressure increase determination time until a certain time after the engine 10 shifts to the fuel cut state.

  Further, in each of the above-described embodiments, the set values of the high-pressure side feed fuel pressure P2 and the low-pressure side feed fuel pressure P1 that define the fuel pressure control range by the fuel pressure variable mechanism 40 are preset values, but at least 1 It is also possible to detect the pulsation width of the actual fuel pressure detected by the fuel pressure sensor 65 under one specific operation state, for example, a specific operation state for each of a plurality of operation regions having different operation conditions, and correct based on the pulsation width. Conceivable.

  Further, the fuel stop state of the internal combustion engine according to the present invention is not limited to the above-described fuel cut state, and fuel injection from the port injection injector 27 corresponding to some cylinders 11 among the plurality of cylinders 11 of the engine 10. May be in a fuel cut operation state in which the engine is temporarily stopped, or in an operation state in which a cylinder deactivation operation for each bank in a V-type engine or the like is performed.

  As described above, the fuel pressure control device according to the present invention allows the fuel pump discharge when the supply fuel pressure to the fuel consuming unit rises to reach the set upper limit pressure while the fuel consuming unit is stopped. Since the pressure is controlled to a pressure different from the set upper limit pressure by the variable fuel pressure mechanism, when the fuel is stopped, the relief valve is urged to open or close to suppress repeated opening and closing operations. A fuel pressure control device that can sufficiently improve the reliability of the relief valve can be provided. The present invention as described above is useful for all fuel pressure control devices that can control the fuel supply pressure of an internal combustion engine.

10 Engine (Internal combustion engine, Fuel consumption part)
11 cylinder 13 combustion chamber 20 first fuel supply mechanism 21 fuel tank 21a sub tank 22 feed pump (fuel pump)
23 Relief valve (safety valve)
24 Reduction valve 25 First fuel pipe (low pressure fuel pipe)
26 Low pressure delivery pipe (low pressure fuel piping)
27 Port injector (fuel injection valve)
28 Fuel Pressure Control Circuit 29 Jet Pump 30 Second Fuel Supply Mechanism 31 Fuel Pressurization Pump 35 Second Fuel Pipe 36 High Pressure Side Delivery Pipe 37 In-Cylinder Injector 40 Fuel Pressure Variable Mechanism 50 ECU
61 Accelerator opening sensor 62 Air flow meter 63 Crank angle sensor 64 Water temperature sensor 65 Low pressure side fuel pressure sensor (fuel pressure sensor)
91 Throttle element P1 Low pressure feed fuel pressure (low pressure supply pressure)
P2 Feed fuel pressure on the high pressure side (supply pressure on the high pressure side)
Pd Feed pump discharge pressure (fuel pump discharge pressure)
Pi Pressure different from the set upper limit pressure (pressure higher than the set upper limit pressure, pressure lower than the set upper limit pressure)
Pr setting upper limit pressure (relief valve opening set pressure, safety valve set pressure)

Claims (7)

A fuel pump for supplying the fuel to a fuel consuming portion capable of transitioning from a fuel consuming state that operates while consuming fuel to a fuel stopped state that temporarily stops consuming fuel; and from the fuel pump to the fuel consuming portion A relief valve that limits a supply pressure of the fuel supplied to a preset upper limit pressure or less, and a fuel pressure variable mechanism that variably controls the supply pressure according to an operating state of the fuel consumption unit. A pressure control device,
The variable fuel pressure mechanism is configured so that the supply pressure of the fuel pump under the fuel stop state is increased on the condition that the supply pressure rises so as to reach the set upper limit pressure after the fuel consumption unit has shifted to the fuel stop state. The fuel pressure control apparatus, wherein the discharge pressure is controlled to a pressure different from the set upper limit pressure.   The fuel pressure variable mechanism sets the discharge pressure of the fuel pump on the condition that the set upper limit pressure is within a fluctuation range of the supply pressure after the fuel consuming unit shifts to the fuel stop state. The fuel pressure control device according to claim 1, wherein the fuel pressure control device is controlled to a pressure different from the upper limit pressure.   The fuel pressure variable mechanism controls the discharge pressure of the fuel pump to a pressure higher than the set upper limit pressure when the supply pressure in the fuel stop state reaches the set upper limit pressure. The fuel pressure control device described in 1.   The fuel pressure variable mechanism controls the discharge pressure of the fuel pump to a pressure lower than the set upper limit pressure on condition that the set upper limit pressure is within a fluctuation range of the supply pressure. 3. The fuel pressure control device according to 2.   The fuel pressure variable mechanism controls the discharge pressure of the fuel pump to a pressure lower than the set upper limit pressure when the supply pressure in the fuel stop state reaches the set upper limit pressure. The fuel pressure control device described in 1. The fuel consumption unit is an internal combustion engine that consumes fuel while being injected by a fuel injection valve, and the supply pressure is a pressure of fuel supplied to the fuel injection valve,
The fuel pressure variable mechanism variably controls the supply pressure within a fuel pressure control range equal to or lower than the set upper limit pressure when the internal combustion engine is in the fuel consumption state, while the set upper limit pressure is in the fuel stop state. 6. The method according to claim 1, wherein when the supply pressure is within a fluctuation range, the discharge pressure of the fuel pump is controlled to be higher than the fuel pressure control range. The fuel pressure control apparatus as described.   It is possible to switch between a first operating state in which the valve is opened at a low set pressure lower than the set upper limit pressure and a second operating state in which the valve is not opened even when the supply pressure reaches or exceeds the low pressure set pressure. The fuel pressure control device according to any one of claims 1 to 6, further comprising a reduction valve capable of reducing the supply pressure to the low pressure setting pressure.

Images