fuel supply unit

Abstract

To continue fuel supply to an injector.SOLUTION: A fuel supply device includes a pump housing having a suction port connected to a low-pressure flow passage on a fuel tank side, a discharge port connected to a high-pressure flow passage on an injector side and a bypass port connected to a check valve. The fuel supply device includes a fuel storage housing having an input port connected to the bypass port via the check valve and an output port connected to the high-pressure flow passage via a bypass flow passage. When fuel pressure in the high-pressure flow passage is below a threshold value, a control system switches a solenoid valve provided in the bypass flow passage from a close state to an open state.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a fuel supply device. Background Art

[0002] An engine, which is an internal combustion engine, includes a high-pressure fuel pump that pressure-feeds fuel toward an injector (see Patent Documents 1 to 4). Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2002-310037 Patent Document 2 Japanese Unexamined Patent Publication No. 2021-21360 Patent Document 3 Japanese Unexamined Patent Publication No. 2012-122403 Patent Document 4 Japanese Unexamined Patent Publication No. 6-173834 Summary of the Invention Problems to be Solved by the Invention

[0004] Incidentally, when the temperature of fuel flowing through a fuel pipe increases and fuel vapor is generated within the fuel pipe, it becomes difficult for the high-pressure fuel pump to pressure-feed fuel toward the injector. For this reason, there is a demand for continuing fuel supply to the injector even when fuel vapor is generated within the fuel pipe. Means for Solving the Problem

[0005] According to this disclosure, a fuel supply device is a fuel supply device that supplies fuel from a fuel tank to an injector, and comprises a pump housing having an intake port connected to a low-pressure passage on the fuel tank side, a discharge port connected to a high-pressure passage on the injector side, and a bypass port connected to a check valve; a fuel storage housing having a plunger reciprocally mounted in the pump housing and changing the volume of a pump chamber partitioned inside the pump housing, an input port connected to the bypass port via the check valve, and an output port connected to the high-pressure passage via the bypass passage; a solenoid valve provided in the bypass passage and operating in an open state that connects the bypass passage and a closed state that blocks the bypass passage; and a control system comprising a processor and memory communicated with each other, which controls the solenoid valve, wherein the control system switches the solenoid valve from the closed state to the open state when the fuel pressure in the high-pressure passage falls below a threshold. [Effects of the Invention]

[0006] According to this disclosure, fuel can be continuously supplied to the injector. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a vehicle equipped with a fuel supply system. [Figure 2] This figure shows a fuel supply device according to one embodiment. [Figure 3] This figure shows an example of a high-pressure fuel pump. [Figure 4] This figure shows an example of the operation status of a high-pressure fuel pump. [Figure 5] This figure shows an example of the operation status of a high-pressure fuel pump. [Figure 6] This is a diagram showing an example of the basic structure of a control unit. [Figure 7] This flowchart shows an example of the procedure for performing operation maintenance control. [Figure 8]This figure shows an example of the operation status of the intermittent supply mode. [Figure 9] This figure shows an example of the operation status of the intermittent supply mode. [Figure 10] This is a timing chart showing an example of the execution status of the operation maintenance control. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described in detail below with reference to the drawings. In the following description, identical or substantially identical components and elements will be denoted by the same reference numerals, and repeated descriptions will be omitted.

[0009] <Vehicle configuration> Figure 1 shows an example of a vehicle 11 equipped with a fuel supply device 10. As shown in Figure 1, the vehicle 11 has a power unit 14 consisting of an engine 12 and a transmission 13. The output shaft 15 of the power unit 14 is connected to the wheels 18 via a propeller shaft 16 and a differential mechanism 17. The vehicle 11 also has a fuel tank 20 for storing fuel such as gasoline, and a high-pressure fuel pump 21 provided on the engine 12. The fuel tank 20 and the high-pressure fuel pump 21 are connected to each other via a low-pressure fuel pipe 22.

[0010] <Engine> Figure 2 shows a fuel supply device 10 according to one embodiment. As shown in Figure 2, the engine 12 has a cylinder block 31 that houses a piston 30 and a cylinder head 32 mounted on the cylinder block 31. The cylinder head 32 has an intake port 34 that communicates with the combustion chamber 33 and an intake valve 35 that opens and closes the intake port 34. The cylinder head 32 also has an exhaust port 36 that communicates with the combustion chamber 33 and an exhaust valve 37 that opens and closes the exhaust port 36. Furthermore, the cylinder head 32 has an intake camshaft 38 that drives the intake valve 35 and an exhaust camshaft 39 that drives the exhaust valve 37. The intake camshaft 38 and the exhaust camshaft 39 are connected to a crankshaft (not shown) via a timing chain or the like.

[0011] <Fuel supply device> As shown in Figure 2, the engine 12 has an injector 40 that injects fuel into the combustion chamber 33. The fuel supply device 10 that supplies fuel from the fuel tank 20 to the injector 40 has a low-pressure fuel pump 41 housed in the fuel tank 20 and a high-pressure fuel pump 21 that pumps fuel towards the injector 40. The low-pressure fuel pump 41 and the high-pressure fuel pump 21 are connected to each other via a low-pressure fuel pipe 22. The high-pressure fuel pump 21 and the injector 40 are connected to each other via a high-pressure fuel pipe 42 and a delivery pipe 43. Furthermore, the delivery pipe 43 and the fuel tank 20 are connected to each other via a pressure regulating valve 44 and a return pipe 45. As the low-pressure fuel pump 41, a trochoid pump or a Wesco pump driven by an electric motor can be used.

[0012] <Pump Housing> FIG. 3 is a diagram illustrating an example of the high-pressure fuel pump 21. As shown in FIG. 3, the high-pressure fuel pump 21 includes a pump housing 51 that internally defines a pump chamber 50, a plunger 52 provided reciprocally in the pump housing 51, and a return spring 53 that biases the plunger 52 in the retreat direction. The pump housing 51 has a suction port 51i connected to a low-pressure fuel pipe (low-pressure flow path) 22 on the fuel tank 20 side, and a discharge port 51o connected to a high-pressure fuel pipe (high-pressure flow path) 42 on the injector 40 side via a check valve 54. The check valve 54 allows fuel flow from the pump chamber 50 toward the high-pressure fuel pipe 42, and blocks fuel flow from the high-pressure fuel pipe 42 toward the pump chamber 50.

[0013] The high-pressure fuel pump 21 includes a pump cam 55 coupled to an intake camshaft 38, and a lifter 56 positioned between the pump cam 55 and the plunger 52. The high-pressure fuel pump 21 further includes a port opening / closing valve 57 that opens and closes the suction port 51i. This port opening / closing valve 57 is an opening / closing valve driven by the electromagnetic force of a solenoid. When the pump cam 55 is rotated by the intake camshaft 38, the plunger 52 reciprocates following the cam surface of the pump cam 55. That is, the plunger 52 moves between an advanced position that reduces the volume of the pump chamber 50, and a retreated position that expands the volume of the pump chamber 50. In this manner, the plunger 52 changes the volume of the pump chamber 50.

[0014] Figures 4 and 5 are diagrams showing an example of the operating state of the high-pressure fuel pump 21. As shown in Figure 4, when the plunger 52 moves toward the retracted position, the port opening / closing valve 57 opens the suction port 51i. That is, by opening the suction port 51i and expanding the pump chamber 50, fuel is sucked into the pump chamber 50 from the low-pressure fuel pipe 22 as indicated by arrow FL1. Thereafter, as shown in Figure 5, when the plunger 52 moves toward the advanced position, the port opening / closing valve 57 closes the suction port 51i. That is, by closing the suction port 51i and reducing the volume of the pump chamber 50, as indicated by arrow FL2, the fuel in the pump chamber 50 is pressure-fed to the delivery pipe (high-pressure flow path) 43 via the check valve 54 and the high-pressure fuel pipe 42. In this way, by opening and closing the suction port 51i in accordance with the reciprocating motion of the plunger 52, fuel can be pressure-fed from the low-pressure fuel pipe 22 to the high-pressure fuel pipe 42.

[0015] <燃料貯蔵ハウジング> As shown in Figure 3, the pump housing 51 has a bypass port 51b connected to a check valve 60 in addition to the suction port 51i and the discharge port 51o. Further, the high-pressure fuel pump 21 has a fuel storage housing 62 that defines a fuel storage chamber 61 inside. The fuel storage housing 62 has an input port 62i connected to the bypass port 51b via the check valve 60, and an output port 62o connected to the high-pressure fuel pipe 42 via a bypass pipe (bypass flow path) 63. Further, the fuel storage chamber 61 has a sufficient volume to maintain the fuel pressure described later. Alternatively, the fuel storage chamber 61 may be provided with an accumulator.

[0016] Furthermore, the high-pressure fuel pump 21 has a bypass on / off valve (solenoid valve) 64 provided in the bypass piping 63. This bypass on / off valve 64 is an on / off valve driven by the electromagnetic force of a solenoid. The bypass on / off valve 64 can be operated to an open state that connects the bypass piping 63 and a closed state that blocks the bypass piping 63. The check valve 60 allows fuel flow from the pump chamber 50 to the fuel storage chamber 61 and blocks fuel flow from the fuel storage chamber 61 to the pump chamber 50.

[0017] <Control System> As shown in Figure 2, the fuel supply device 10 has a control system 70 consisting of multiple electronic control units. The electronic control units constituting the control system 70 include an engine control unit 71 and a vehicle control unit 72. The engine control unit 71 is an electronic control unit that outputs control signals to the injector 40, low-pressure fuel pump 41, port on / off valve 57, and bypass on / off valve 64, etc. The vehicle control unit 72 is an electronic control unit that outputs control signals to the engine control unit 71, etc. The engine control unit 71 and the vehicle control unit 72 are connected to each other so as to be able to communicate with each other via an in-vehicle network 73 such as CAN (Controller Area Network).

[0018] The vehicle control unit 72 is connected to an accelerator sensor 74 that detects the amount of accelerator pedal operation, a brake sensor 75 that detects the amount of brake pedal operation, and a vehicle speed sensor 76 that detects the vehicle speed, which is the speed at which the vehicle 11 is traveling. The vehicle control unit 72 is also connected to a start switch 77 that is manually operated when the control system 70 is started and the engine 12 is started. Furthermore, the engine control unit 71 is connected to a pressure sensor 78 that detects the pressure of the fuel flowing through the high-pressure fuel pipe 42.

[0019] Figure 6 shows an example of the basic structure of control units 71 and 72. As shown in Figure 6, the control units 71 and 72, which are electronic control units, have a microcontroller 82 that incorporates a processor 80 and a main memory (memory) 81, etc. A predetermined program is stored in the main memory 81, and the program is executed by the processor 80. The processor 80 and the main memory 81 are connected to each other so as to be able to communicate with each other. Note that the microcontroller 82 may incorporate multiple processors 80, and the microcontroller 82 may also incorporate multiple main memories 81.

[0020] Furthermore, the control units 71 and 72 include an input circuit 83, a drive circuit 84, a communication circuit 85, an external memory 86, and a power supply circuit 87. The input circuit 83 converts signals input from various sensors into signals that can be input to the microcontroller 82. The drive circuit 84 generates drive signals for devices such as the injector 40 based on signals output from the microcontroller 82. The communication circuit 85 converts signals output from the microcontroller 82 into communication signals for other control units. The communication circuit 85 also converts communication signals received from other control units into signals that can be input to the microcontroller 82. In addition, the power supply circuit 87 supplies a stable power supply voltage to the microcontroller 82, input circuit 83, drive circuit 84, communication circuit 85, and external memory 86, etc. Furthermore, the external memory 86, which consists of non-volatile memory, stores programs and various data.

[0021] <Operation and Maintenance Control: Flowchart> However, since the fuel discharged from the low-pressure fuel pump 41 is at a low pressure, there is a risk that vapor, or fuel vapor, may be generated in the low-pressure fuel piping 22 if the fuel temperature rises. When fuel vapor is generated in the low-pressure fuel piping 22 in this way, it flows from the low-pressure fuel piping 22 into the pump chamber 50, making it difficult for the plunger 52 to pressurize the fuel in the pump chamber 50. If the fuel supply from the pump chamber 50 to the high-pressure fuel piping 42 is stagnant, the amount of fuel vapor in the low-pressure fuel piping 22 will increase as the fuel temperature rises further, and there is a risk that the engine will stall due to insufficient fuel injection amount resulting from the drop in fuel pressure. To avoid this engine stall due to fuel vapor, the control system 70 performs operation maintenance control that continues to supply a minimum amount of fuel to the injector 40 even if fuel vapor is generated in the low-pressure fuel piping 22.

[0022] Next, we will describe the operation maintenance control that maintains the operating state of the engine 12. Figure 7 is a flowchart showing an example of the procedure for executing the operation maintenance control. Each step of the operation maintenance control shown in Figure 7 is executed by the processor 80 that constitutes the control system 70. Furthermore, the operation maintenance control shown in Figure 7 is a control that is executed by the control system 70 at predetermined intervals after the control system 70 has been started.

[0023] As shown in Figure 7, the control system 70 proceeds to step S10 and executes a supply stop mode (first control mode) in which the bypass on / off valve 64 is kept in the closed state. As shown in Figures 4 and 5, in the supply stop mode executed during normal operation of the engine 12, the bypass on / off valve 64 is kept in the closed state, so that fuel at the same pressure as the pump chamber 50 is stored in the fuel storage chamber 61 in the fuel storage housing 62. Then, as shown in Figure 7, after executing the supply stop mode in step S10, the control system 70 proceeds to step S11 and determines whether the fuel pressure P1 in the high-pressure fuel piping 42 falls below a predetermined threshold X1.

[0024] Here, the situation in which the fuel pressure P1 in the high-pressure fuel piping 42 drops below the threshold X1 is when fuel vapor generated in the low-pressure fuel piping 22 flows into the pump room 50, and the fuel supply from the pump room 50 to the high-pressure fuel piping 42 begins to be interrupted. When the control system 70 determines in step S11 that the fuel pressure P1 has fallen below the threshold X1, it proceeds to step S12 and executes an intermittent supply mode (second control mode) in which the bypass on / off valve 64 is alternately switched between a closed state and an open state.

[0025] Figures 8 and 9 show an example of the operation of the intermittent supply mode. As shown in Figures 8 and 9, in the intermittent supply mode, while fuel is continuously being pumped from the high-pressure fuel pump 21 to the high-pressure fuel piping 42, the bypass on / off valve 64 is alternately switched between a closed state and an open state. As a result, even if the amount of fuel supplied from the pump room 50 to the high-pressure fuel piping 42 decreases due to the generation of fuel vapor, fuel is supplied from the fuel storage room 61 to the high-pressure fuel piping 42 to compensate for this decrease in fuel.

[0026] In this way, even if fuel vapor is generated in the low-pressure fuel line 22, by controlling the bypass on / off valve 64 in intermittent supply mode, a minimum fuel supply to the injector 40 can be continued, and engine stall can be avoided. Moreover, since the fuel flow from the low-pressure fuel line 22 to the high-pressure fuel line 42 is maintained, the fuel temperature can be lowered while consuming the fuel vapor in the low-pressure fuel line 22, and the fuel vapor in the low-pressure fuel line 22 can be properly eliminated.

[0027] In other words, as shown in Figure 8, by switching the bypass on / off valve 64 from the closed state to the open state, fuel is supplied from the fuel storage chamber 61 to the high-pressure fuel pipe 42 via the bypass pipe 63, as indicated by arrow FL3. In this way, even if the amount of fuel supplied from the pump chamber 50 to the high-pressure fuel pipe 42 decreases due to the generation of fuel vapor, fuel can be supplied from the fuel storage chamber 61 to the high-pressure fuel pipe 42 to compensate for this decrease, thereby preventing engine stall.

[0028] Furthermore, as shown in Figure 9, by switching the bypass valve 64 from the open state to the closed state, the fuel supply from the fuel storage chamber 61 to the high-pressure fuel piping 42 is cut off, and the fuel pressure in the high-pressure fuel piping 42 temporarily decreases. As a result, even if the fuel pressure in the pump chamber 50 decreases slightly due to the inflow of fuel vapor, fuel can still flow from the pump chamber 50 to the high-pressure fuel piping 42, as indicated by arrow FL4. In other words, as indicated by arrows FL4 and FL5, the fuel flow from the low-pressure fuel piping 22 through the pump chamber 50 to the high-pressure fuel piping 42 is maintained, so the fuel vapor in the low-pressure fuel piping 22 can be crushed and eliminated in the pump chamber 50. In addition, since new fuel flows into the low-pressure fuel piping 22 from the fuel tank 20, the fuel temperature in the low-pressure fuel piping 22 can be actively lowered, and the fuel vapor in the low-pressure fuel piping 22 can be properly eliminated.

[0029] As shown in Figure 7, when the control system 70 executes the intermittent supply mode in step S12, it proceeds to step S13 and determines whether the fuel pressure P1 of the high-pressure fuel pipe 42 exceeds a threshold (second threshold) X2 which is greater than threshold X1. If the control system 70 determines in step S13 that the fuel pressure P1 of the high-pressure fuel pipe 42 is less than or equal to threshold X2, it proceeds to step S12 and continues to control the bypass on / off valve 64 in intermittent supply mode. On the other hand, if the control system 70 determines in step S13 that the fuel pressure P1 of the high-pressure fuel pipe 42 exceeds threshold X2, it proceeds to step S14 and switches the control mode to the supply stop mode and keeps the bypass on / off valve 64 in the closed state.

[0030] In the example shown in Figure 8, fuel is not supplied from the pump chamber 50 to the high-pressure fuel piping 42 at the time the bypass on / off valve 64 is operated to the open position, but this is not the only example. In other words, even when fuel is supplied from the fuel storage chamber 61 to the high-pressure fuel piping 42, fuel will still be supplied from the pump chamber 50 to the high-pressure fuel piping 42 depending on the fuel pressure in the pump chamber 50, which is pressurized by the plunger 52.

[0031] <Operation Maintenance Control: Timing Chart> Next, the aforementioned operation maintenance control will be explained using a timing chart. Figure 10 is a timing chart showing an example of the operation maintenance control execution status. In Figure 10, the fuel pressure P1 in the high-pressure fuel piping 42 is shown by a solid line, the fuel pressure P2 in the fuel storage chamber 61 is shown by a dashed line, and the fuel pressure P3 in the low-pressure fuel piping 22 is shown by a dashed line.

[0032] As shown in Figure 10, when fuel vapor is generated in the low-pressure fuel pipe 22 at time t1, the fuel pressure P3 in the low-pressure fuel pipe 22 decreases (symbol a1), and the fuel pressure P1 in the high-pressure fuel pipe 42 decreases (symbol b1). Then, as shown at time t2, when the fuel pressure P1 in the high-pressure fuel pipe 42 decreases and falls below the threshold X1 (symbol b2), the control system 70 switches the control mode of the bypass on / off valve 64 from the supply stop mode to the intermittent supply mode (symbol c1). As a result, the bypass on / off valve 64 switches from the closed state to the open state (symbol d1), the fuel pressure P1 in the high-pressure fuel pipe 42 increases (symbol b3), and the fuel pressure P2 in the fuel storage chamber 61 decreases (symbol e1).

[0033] Furthermore, after a predetermined time has elapsed since the bypass valve 64 was switched to the open state, the bypass valve 64 is switched from the open state to the closed state (symbol d2). As a result, the fuel pressure P1 in the high-pressure fuel piping 42 decreases (symbol b4), and the fuel pressure P2 in the fuel storage chamber 61 is maintained (symbol e2). This situation of alternately switching the bypass valve 64 between the closed and open states continues throughout the execution period of the intermittent supply mode (symbols d3, d4, d5, d6, d7, d8).

[0034] As described above, by opening and closing the bypass valve 64 through the execution of the intermittent supply mode, an excessive drop in the fuel pressure P1 in the high-pressure fuel line 42 can be avoided. This ensures that a minimum fuel supply to the injector 40 is maintained, preventing engine stall due to fuel shortage. Subsequently, at time t4, when the fuel vapor in the low-pressure fuel line 22 disappears, the fuel pressure P3 in the low-pressure fuel line 22 rises (symbol a2). Also, because the fuel in the pump chamber 50 is appropriately pressurized by the plunger 52, the fuel pressure P1 in the high-pressure fuel line 42 rises (symbol b5), and along with the rise in fuel pressure P1, the fuel pressure P2 in the fuel storage chamber 61 also rises (symbol e3).

[0035] Then, as shown at time t5, when the fuel pressure P1 in the high-pressure fuel line 42 rises and exceeds a threshold X2 which is greater than the threshold X1 (symbol b6), the control system 70 switches the control mode of the bypass on / off valve 64 from intermittent supply mode to supply stop mode (symbol c2). By switching the control mode to supply stop mode in this way, the bypass on / off valve 64 is kept in the closed state (symbol d9).

[0036] This disclosure is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the disclosure. In the above description, the control system 70 is configured by a plurality of control units 71, 72, but it is not limited to this. For example, the control system 70 may be configured by a single control unit. Also, the illustrated engine 12 is a gasoline engine that uses gasoline as fuel, but it is not limited to this, and it may be a diesel engine that uses diesel fuel. Also, the illustrated vehicle 11 is a vehicle equipped only with the engine 12 as a power source, but it is not limited to this, and it may be a hybrid vehicle equipped with the engine 12 and a motor generator as power sources.

[0037] In the example shown in Figure 3, the fuel storage housing 62 is integrally provided with the pump housing 51 of the high-pressure fuel pump 21, but the design is not limited to this. For example, the pump housing 51 and the fuel storage housing 62 may be separated from each other, and the bypass port 51b and the input port 62i may be connected to each other via fuel piping. Also, in the example shown in Figure 3, the bypass on / off valve 64 is incorporated into the fuel storage housing 62, but the design is not limited to this, and the fuel storage housing 62 and the bypass on / off valve 64 may be separated from each other.

[0038] In the above explanation, the control mode of the bypass valve 64 is switched to intermittent supply mode when the fuel pressure P1 in the high-pressure fuel piping 42 falls below a threshold X1, but this is not the only way. For example, the control mode of the bypass valve 64 may be switched to intermittent supply mode when the fuel pressure in the delivery pipe 43 falls below a predetermined threshold. Alternatively, the fuel pressure P1 in the high-pressure fuel piping 42 may be estimated based on the fuel pressure in the pump chamber 50, and the control mode of the bypass valve 64 may be switched accordingly. In other words, the control mode of the bypass valve 64 may be switched to intermittent supply mode when the fuel pressure in the pump chamber 50 falls below a predetermined threshold due to the generation of fuel vapor. Alternatively, the fuel pressure P1 in the high-pressure fuel piping 42 may be estimated based on the fuel pressure in the low-pressure fuel piping 22, and the control mode of the bypass valve 64 may be switched accordingly. In other words, the control mode of the bypass valve 64 may be switched to intermittent supply mode when the fuel pressure in the low-pressure fuel piping 22 falls below a predetermined threshold due to the generation of fuel vapor.

[0039] In the above explanation, the control mode of the bypass valve 64 is switched to the supply stop mode when the fuel pressure P1 in the high-pressure fuel piping 42 exceeds a threshold X2, but it is not limited to this. For example, the control mode of the bypass valve 64 may be switched to the supply stop mode when the fuel pressure in the delivery pipe 43 exceeds a predetermined threshold. Alternatively, the fuel pressure P1 in the high-pressure fuel piping 42 may be estimated based on the fuel pressure in the pump chamber 50, and the control mode of the bypass valve 64 may be switched accordingly. In other words, the control mode of the bypass valve 64 may be switched to the supply stop mode when the fuel pressure in the pump chamber 50 exceeds a predetermined threshold due to the disappearance of fuel vapor. Alternatively, the fuel pressure P1 in the high-pressure fuel piping 42 may be estimated based on the fuel pressure in the low-pressure fuel piping 22, and the control mode of the bypass valve 64 may be switched accordingly. In other words, the control mode of the bypass valve 64 may be switched to the supply stop mode when the fuel pressure in the low-pressure fuel piping 22 exceeds a predetermined threshold due to the disappearance of fuel vapor.

[0040] In the above explanation, when controlling the bypass valve 64 in intermittent supply mode, the bypass valve 64 is controlled to be in the open state for a predetermined period of time, but this is not the only option. For example, since the amount of fuel injected by the injector 40 increases or decreases with engine speed, the time for which the bypass valve 64 is controlled to be in the open state may be changed according to the engine speed. In other words, the time for which the bypass valve 64 is controlled to be in the open state may be set to be longer as the engine speed increases, and the time for which the bypass valve 64 is controlled to be in the open state may be set to be shorter as the engine speed decreases.

[0041] In the above explanation, when controlling the bypass valve 64 in intermittent supply mode, the bypass valve 64 is controlled to be in the closed state for a predetermined time set in advance, but this is not the only option. For example, since the amount of fuel injected by the injector 40 increases or decreases with engine speed, the time for which the bypass valve 64 is controlled to be in the closed state may be changed according to the engine speed. In other words, the time for which the bypass valve 64 is controlled to be in the closed state may be set to be shorter as the engine speed increases, and the time for which the bypass valve 64 is controlled to be in the closed state may be set to be longer as the engine speed decreases.

[0042] In the above explanation, the bypass valve 64 is alternately switched between a closed state and an open state when the fuel pressure P1 in the high-pressure fuel piping 42 falls below the threshold X1, but this is not the only way. For example, depending on the amount of fuel vapor generated in the low-pressure fuel piping 22, the fuel vapor may disappear before the bypass valve 64 is alternately switched between a closed state and an open state. In other words, even when the fuel pressure P1 in the high-pressure fuel piping 42 falls below the threshold X1, the fuel vapor may disappear by switching the bypass valve 64 from a closed state to an open state. In this case, without alternately switching the bypass valve 64 between a closed state and an open state, the control mode of the bypass valve 64 is switched to the supply stop mode, and the bypass valve 64 is held in the closed state. [Explanation of Symbols]

[0043] 10 Fuel supply device 20 fuel tanks 22 Low-pressure fuel piping (low-pressure flow path) 40 Injectors 42. High-pressure fuel piping (high-pressure flow path) 43 Delivery pipe (high-pressure flow path) 50 Pump Room 51 Pump Housing 51i Inhalation Port 51o Discharge port 51b Bypassport 52 Plungers 60 Check valve 61 Fuel storage room 62 Fuel Storage Housing 62i input port 62° output port 63 Bypass piping (bypass flow path) 64 Bypass valve (solenoid valve) 70 Control Systems 80 processors 81 Main memory (memory) P1 Fuel pressure X1 threshold X2 Second threshold

Claims

1. A fuel supply device that supplies fuel from a fuel tank to an injector, A pump housing comprising an intake port connected to the low-pressure passage on the fuel tank side, a discharge port connected to the high-pressure passage on the injector side, and a bypass port connected to a check valve, A plunger is provided in the pump housing so as to be reciprocable and changes the volume of the pump chamber partitioned inside the pump housing, A fuel storage housing comprising an input port connected to the bypass port via the check valve, and an output port connected to the high-pressure flow path via a bypass flow path, An electromagnetic valve is provided in the bypass channel and operates in an open state that connects the bypass channel and a closed state that blocks the bypass channel. A control system comprising a processor and memory connected to each other in a manner that enables communication, for controlling the electromagnetic valve, It has, The control system is When the fuel pressure in the high-pressure passage falls below a threshold, the electromagnetic valve is switched from a closed state to an open state. Fuel supply device.

2. In the fuel supply device according to claim 1, The control system is When the fuel pressure in the high-pressure passage falls below the threshold, the electromagnetic valve is alternately switched between a closed state and an open state. Fuel supply device.

3. In the fuel supply device according to claim 1, The control system is When the fuel pressure in the high-pressure passage falls below the threshold, the control mode of the solenoid valve is switched from a first control mode in which the solenoid valve is held in a closed state to a second control mode in which the solenoid valve is alternately switched between a closed state and an open state. Fuel supply device.

4. In the fuel supply device according to claim 3, The control system is While the second control mode is being executed, if the fuel pressure in the high-pressure passage exceeds a second threshold that is greater than the threshold, the control mode of the solenoid valve is switched from the second control mode to the first control mode. Fuel supply device.

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