Fuel supply device for internal combustion engine

Abstract

A fuel supply device of an internal combustion engine, a control device of the fuel supply device having a processing circuit that performs processing of determining whether or not fuel leaks in a fuel passage on a downstream side of a second stop valve. The second stop valve has a first valve body that allows fuel to flow from an upstream side of the second stop valve to a downstream side of the second stop valve if the first valve body is opened by energization, and a second valve body that is opened if a pressure difference between a pressure on the upstream side of the second stop valve and a pressure on the downstream side of the second stop valve becomes equal to or less than a predetermined value. The processing circuit performs processing of acquiring an opening time required from when energization to the second stop valve is started until opening of the second valve body is completed, calculating a difference between a fuel pressure at the time when energization to the second stop valve is started and a fuel pressure at the time when opening of the second valve body is completed, calculating a leakage amount of fuel in the fuel passage on the downstream side of the second stop valve based on the opening time and the difference, and determining whether or not fuel leaks based on the calculated leakage amount.

Description

Technical Field

[0001] This invention relates to a fuel supply device for an internal combustion engine. Background Technology

[0002] Internal combustion engines that use hydrogen as fuel are known. During engine shutdown in such internal combustion engines, fuel leakage can occur, for example, if the fuel injection valve malfunctions. Therefore, it is necessary to detect fuel leakage from the fuel passage, including the fuel injection valve. Thus, for example, in the internal combustion engine described in Patent Document 1, a hydrogen detection sensor for detecting hydrogen leakage from the fuel system is provided on the upper cover of the cylinder head cover.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-82746 Summary of the Invention

[0004] When using the aforementioned hydrogen detection sensor to detect fuel leaks, if the hydrogen detection section of the hydrogen detection sensor is not positioned appropriately, the hydrogen leak may not be detected properly.

[0005] A fuel supply device for an internal combustion engine that solves the above-mentioned problems includes: a tank for storing hydrogen gas, which is used as fuel for the internal combustion engine; a fuel injection valve for supplying the fuel to a cylinder; a fuel passage for supplying the fuel from the tank to the fuel injection valve; a solenoid valve disposed in the fuel passage and for opening and closing the fuel passage; a pressure sensor for detecting the fuel pressure in the fuel passage downstream of the solenoid valve in the direction of fuel flow; and a control device having a processing circuit that performs a process to determine whether there is a fuel leak in the downstream fuel passage. The solenoid valve includes: a first valve body that opens when energized, thereby allowing fuel to flow from the upstream side of the solenoid valve to the downstream side; and a second valve body that opens when the pressure difference between the upstream side of the solenoid valve and the downstream side of the solenoid valve is below a predetermined value. The processing circuit performs the following processing: obtaining the valve opening time required from the start of energizing the solenoid valve to the end of the valve opening of the second valve body; calculating the difference between the fuel pressure at the start of energizing the solenoid valve and the fuel pressure at the end of the valve opening of the second valve body; calculating the amount of fuel leakage in the fuel passage on the downstream side based on the valve opening time and the difference; and determining whether there is fuel leakage based on the amount of leakage.

[0006] Invention Effects

[0007] The internal combustion engine's fuel supply system is capable of properly detecting hydrogen leaks. Attached Figure Description

[0008] Figure 1This is a schematic diagram illustrating an internal combustion engine, a fuel supply system, and a control device for an application of a solenoid valve in one embodiment.

[0009] Figure 2 This is a cross-sectional view showing the structure of the second shut-off valve in this embodiment.

[0010] Figure 3 This is a time series graph showing the shift of various values ​​when a hydrogen leak occurs. Figure 3 (A) indicates the progression of the internal combustion engine's operating state. Figure 3 (B) indicates the change in the energized state of the second shut-off valve. Figure 3 (C) indicates the change in fuel temperature. Figure 3 (D) indicates the shift of the third pressure. Detailed Implementation

[0011] The following is for reference. Figures 1-3 An embodiment of a fuel supply device for an internal combustion engine will be described.

[0012] <Structure of the fuel supply system for an internal combustion engine>

[0013] Figure 1 The internal combustion engine 10 shown is installed in a vehicle and is an internal combustion engine that uses hydrogen as a fluid gaseous fuel. Alternatively, the vehicle may be a hybrid vehicle, for example, that includes both the internal combustion engine 10 and an electric motor as the prime mover. In such a hybrid vehicle, the internal combustion engine 10 operates intermittently.

[0014] A throttle valve 12 for adjusting the amount of intake air is provided in the intake passage 11 of the internal combustion engine 10.

[0015] The internal combustion engine 10 has a fuel supply device 300 including a fuel injection valve 15, a tank 20, a fuel pipe 40, a first shut-off valve 21, a second shut-off valve 22, a pressure reducing valve 30, and a delivery pipe 60.

[0016] Fuel injection valve 15 supplies fuel to cylinder 10a of internal combustion engine 10. Tank 20 stores hydrogen as a gaseous fuel under high pressure. Fuel piping 40 connects tank 20 and delivery pipe 60. Fuel injection valve 15 is connected to delivery pipe 60. Fuel piping 40 and delivery pipe 60 form the fuel passage connecting tank 20 and fuel injection valve 15. Hydrogen stored in tank 20 is supplied to fuel injection valve 15 via fuel piping 40 and delivery pipe 60.

[0017] In the fuel piping 40, a first shut-off valve 21, a pressure reducing valve 30, and a second shut-off valve 22 are arranged sequentially in the direction of fuel flow. Furthermore, hereinafter, the upstream side in the direction of fuel flow will be referred to as "upstream," and the downstream side in the direction of fuel flow will be referred to as "downstream."

[0018] The first shut-off valve 21 is a solenoid valve and is located near the outlet of tank 20. When the first shut-off valve 21 is open, fuel is supplied from tank 20 to fuel line 40. When the first shut-off valve 21 is closed, the fuel supply from tank 20 to fuel line 40 is stopped.

[0019] The pressure reducing valve 30 is used to reduce the fuel pressure, i.e. combustion pressure, of the hydrogen stored in the tank 20 under high pressure to a specified pressure (e.g., about 4 MPa) and supply it to the fuel injection valve 15.

[0020] The second shut-off valve 22 is a solenoid valve, located near the delivery pipe 60 in the fuel piping 40. When the second shut-off valve 22 is opened by energization, fuel is supplied to the delivery pipe 60. When the second shut-off valve 22 is closed by de-energization, the fuel supply to the delivery pipe 60 is stopped.

[0021] The first shut-off valve 21 and the second shut-off valve 22 are closed during the operation of the internal combustion engine 10. On the other hand, the first shut-off valve 21 and the second shut-off valve 22 are substantially open during the operation of the internal combustion engine 10.

[0022] The first pressure sensor 81, located on the fuel pipe 40 between the first shut-off valve 21 and the pressure reducing valve 30, detects the fuel pressure, i.e., the first pressure P1, within the fuel pipe 40 between the first shut-off valve 21 and the pressure reducing valve 30.

[0023] The second pressure sensor 82, located on the fuel pipe 40 between the pressure reducing valve 30 and the second shut-off valve 22, detects the fuel pressure, i.e., the second pressure P2, within the fuel pipe 40 between the pressure reducing valve 30 and the second shut-off valve 22.

[0024] The third pressure sensor 83, located on the fuel delivery pipe 60, detects the fuel pressure, i.e., the third pressure P3, in the delivery pipe 60. The third pressure sensor 83 is a pressure sensor that detects the fuel pressure, i.e., the third pressure P3, in the fuel passage located downstream of the second shut-off valve 22 when viewed in the direction of fuel flow.

[0025] Temperature sensor 84, installed in delivery pipe 60, detects the temperature of the fuel, i.e., the fuel temperature THF, within delivery pipe 60. Temperature sensor 84 is a temperature sensor that detects the fuel temperature in the fuel passage located downstream of the solenoid valve when viewed along the fuel flow direction.

[0026] The control device 100 performs various controls, such as fuel injection, of the internal combustion engine 10 by controlling various controlled objects, including the throttle valve 12, fuel injection valve 15, first shut-off valve 21, and second shut-off valve 22. The control device 100 has a processing circuit 110 composed of a CPU or a memory. In the processing circuit 110, various controls are performed by the CPU executing programs stored in the memory.

[0027] The control device 100 references various values ​​required for controlling the internal combustion engine 10. For example, the control device 100 references the detection values ​​of the first pressure sensor 81, the second pressure sensor 82, the third pressure sensor 83, and the temperature sensor 84. Furthermore, the control device 100 references the detection signal of the throttle position sensor 71, which measures the amount of throttle operation (ACCP) by the driver operating the accelerator pedal 27 of the vehicle equipped with the internal combustion engine 10. The control device 100 also references the detection signal of the speed sensor 72, which detects the vehicle speed (SP) of the vehicle equipped with the internal combustion engine 10. Additionally, the control device 100 references the detection signal of the airflow meter 73, which detects the intake air volume (GA) of the internal combustion engine 10, and the detection signal (Scr) of the crankshaft angle sensor 74, which detects the crankshaft rotation angle of the internal combustion engine 10.

[0028] The control unit 100 calculates the engine speed NE based on the detection signal Scr from the crankshaft angle sensor 74. Furthermore, the control unit 100 calculates the engine load rate KL based on the engine speed NE and the intake air volume GA. The engine load rate KL represents the ratio of the current cylinder air intake volume to the cylinder air intake volume during stable operation of the internal combustion engine 10 at full load at the current engine speed NE. Additionally, the cylinder air intake volume is the amount of air that flows into each cylinder during the intake stroke.

[0029] If an engine stop request is generated due to predetermined stop conditions, the control device 100 stops the operation of the internal combustion engine 10. Conversely, if an engine start request is generated due to predetermined start conditions, the control device 100 starts the stopped internal combustion engine 10. Thus, intermittent stop and start are repeatedly performed on the internal combustion engine 10.

[0030] <Structure of the second shut-off valve>

[0031] Figure 3 The structure of the second shut-off valve 22 described above is shown in the figure. Furthermore, the direction along the central axis L of the plunger 211 of the second shut-off valve 22 will be referred to as the axial direction. And the direction orthogonal to the axial direction will be referred to as the radial direction.

[0032] The second shut-off valve 22 includes a housing 200, a stator 230, an electromagnetic coil 240, a first valve 210, a retainer 250, and a second valve 220.

[0033] The housing 200 has an inlet port 201 connected to a fuel line 40 connected to a pressure reducing valve 30 and an outlet port 203 connected to a fuel line 40 connected to a delivery pipe 60.

[0034] The inlet port 201 and the outlet port 203 are connected via a space formed within the housing 200, namely the first chamber 202.

[0035] The stator 230 is cylindrical and is housed within the housing 200.

[0036] An electromagnetic coil 240 is disposed on the outer periphery of the stator 230. The electromagnetic coil 240 opens the valve body when energized. The drive circuit driving the electromagnetic coil 240 is connected to the aforementioned control device 100.

[0037] The first valve 210, which is the first valve body, has a plunger 211 that moves axially within the stator 230 and a first sealing member 213 that opens and closes the first fuel passage 222 by moving the plunger 211.

[0038] One end of the plunger 211 becomes a protrusion 212 protruding from the stator 230. The first sealing member 213 described above is provided at the front end of the protrusion 212. Furthermore, the protrusion 212 has a pin 214 extending radially. Both ends of the pin 214 protrude from the outer peripheral surface of the protrusion 212.

[0039] The retainer 250 has a cylindrical portion 251 coaxial with the central axis L. The inner circumferential surface of the cylindrical portion 251 is opposite to and separate from the outer circumferential surface of the aforementioned protrusion 212.

[0040] The second valve 220, which is the second valve body, is slidably received on the inner peripheral surface of the cylindrical portion 251. The second valve 220 has a hole 221 formed in which the outer peripheral surface of the protrusion 212 of the first valve 210 slides. An elongated hole 225 is formed in the second valve 220 for the insertion of the aforementioned pin 214 and for allowing the pin 214 to move axially.

[0041] The first fuel passage 222, which extends axially, is formed at the front end of the second valve 220. The first fuel passage 222 is connected to the outlet port 203 that constitutes the second fuel passage. The outlet port 203 is a fuel passage with a flow path cross-sectional area larger than that of the first fuel passage 222.

[0042] A second sealing member 224 is provided at the front end of the second valve 220 to open and close the outlet port 203. More specifically, the second sealing member 224 opens and closes a second valve seat 204 located at one end of the outlet port 203. The outlet port 203 is a fuel passage opened and closed by the second valve 220. The diameter of the outlet port 203 is set such that the speed of the fuel flowing through the outlet port 203 is the speed of sound.

[0043] A first valve seat 223 protruding toward the protrusion 212 is formed at the front end of the second valve 220, which has the first fuel passage 222. The first fuel passage 222 is opened and closed by the first sealing member 213 through the first valve seat 223. The first fuel passage 222 is a communication passage that connects the upstream flow path of the second valve 220, which is the second valve body, with the downstream flow path of the second valve 220. The flow path upstream of the second valve 220 includes the pressure chamber 227 (described later), the communication passage 226 (described later), the first chamber 202, and the inlet port 201 (described later). The flow path downstream of the second valve 220 includes the outlet port 203. The first valve 210 is the first valve body that opens and closes the first fuel passage 222 before the second valve 220 opens.

[0044] In the orifice 221, the space surrounded by the walls surrounding the first valve seat 223 and the front end face of the protrusion 212 becomes a pressure chamber 227 that exerts pressure on the second valve 220 in the closing direction. This pressure chamber 227 is connected to the first chamber 202 via a connecting passage 226.

[0045] A second chamber 255 is formed on the inner circumferential surface of the cylindrical portion 251 of the retainer 250 to ensure the axial stroke of the second valve 220.

[0046] In the second valve 220, the end face 228 opposite to the side where the second sealing member 224 is located and the limiting portion 253 in the retainer 250, which is formed by the surface opposite to the end face 228, abut against each other when the second valve 220 is fully open after opening. The abutment between these end faces 228 and the limiting portion 253 stabilizes the position of the valve body when the second valve 220 is fully open.

[0047] An end cap 280 is provided inside the stator 230 at the end opposite to the side where the plunger 211 is inserted, to close that end. A third chamber 257 is formed between the end cap 280 and the plunger 211 as a space. Furthermore, a spring 215 is provided between the end cap 280 and the plunger 211 to exert force on the plunger 211 in a direction away from the end cap 280.

[0048] <Opening and closing action of the second shut-off valve>

[0049] If the plunger 211 is pulled into the stator 230 by energizing the electromagnetic coil 240, the first valve 210 moves in the direction that the first sealing member 213 separates from the first valve seat 223, thereby opening the first valve 210. If the first sealing member 213 separates from the first valve seat 223, the fuel flowing in from the inlet port 201 flows into the outlet port 203 via the first chamber 202, the connecting passage 226, the pressure chamber 227, and the first fuel passage 222.

[0050] Then, by moving the first valve 210 in the direction separating the first sealing member 213 from the first valve seat 223, the pin 214 of the first valve 210 contacts the wall surface 229 of the elongated hole 225 of the second valve 220 in the axial direction of the opening direction of the first valve 210. Therefore, an opening force Fop is applied to the second valve 220 in the same direction as the movement direction of the first valve 210. This opening force Fop is an attractive force generated by the magnetic force of the electromagnetic coil 240 and acts in the opening direction of the second valve 220.

[0051] If the first valve 210 opens, the pressure chamber 227 connects to the outlet port 203, thus reducing the pressure difference ΔP between the pressure chamber 227 and the outlet port 203. Consequently, the force resisting the opening of the second valve 220, i.e., the resistance Fcl, decreases. Furthermore, the resistance Fcl includes the force acting in the closing direction of the second valve 220 and the sliding resistance of the second valve 220 and the retainer 250. Moreover, the force acting in the closing direction of the second valve 220 includes the differential pressure load generated by the pressure difference ΔP between the pressure chamber 227 and the outlet port 203, or the force of the spring 215.

[0052] Then, if the opening force Fop is greater than the resistance Fcl, the second valve 220 moves in the direction that the second sealing member 224 separates from the second valve seat 204, thereby opening the second valve 220. If the second sealing member 224 separates from the second valve seat 204, the fuel flowing in from the inlet port 201 flows mainly into the outlet port 203 via the first chamber 202.

[0053] If the second valve 220 is in the fully open state, it will stop moving axially by abutting against the limiting part 253 through the end face 228.

[0054] Fuel flowing into outlet port 203 is delivered to fuel injection valve 15 via fuel pipe 40 and delivery pipe 60.

[0055] If the energization of the electromagnetic coil 240 is stopped, the first valve 210 moves toward the first sealing member 213 and abuts against the first valve seat 223 due to the force of the spring 215, etc. Thus, the first valve 210 is closed.

[0056] If the first sealing member 213 abuts against the first valve seat 223, the force of the spring 215 acts on the second valve 220. Therefore, the second valve 220 moves towards the direction where the second sealing member 224 abuts against the second valve seat 204. Thus, the second valve 220 is closed.

[0057] Thus, in the second shut-off valve 22, the pressure in the pressure chamber 227 is used to open the second valve 220, whose flow path cross-sectional area is larger than that of the outlet port 203 of the first fuel passage 222. That is, the second valve 220 opens when the pressure difference ΔP between the pressure chamber 227 (which is the pressure difference between the upstream and downstream sides of the second shut-off valve 22) and the outlet port 203 becomes smaller and falls below a predetermined value. Therefore, compared to directly using the magnetic force of the electromagnetic coil to open the second valve 220, the magnetic force required to open the valve can be reduced. Therefore, for example, the electromagnetic coil 240 can be miniaturized. In addition, in this embodiment, for example, the attraction force of the electromagnetic coil 240 is set such that the second valve 220 opens when the pressure difference ΔP is almost "0". That is, the sliding resistance between the second valve 220 and the retainer 250 and the force of the resistance spring 215 in the resistance Fcl are set as the attraction force.

[0058] <Regarding hydrogen leak detection>

[0059] The processing circuit 110 determines, by performing the processing described below, whether there is a fuel leak in the fuel passage downstream of the second shut-off valve 22 when viewed in the fuel flow direction. Examples of fuel leaks downstream of the second shut-off valve 22 include fuel leaks from the fuel injection valve 15 caused by malfunction in closing, and fuel leaks from the delivery pipe 60. Furthermore, examples of fuel leaks downstream of the second shut-off valve 22 include fuel leaks from the fuel piping 40 connecting the second shut-off valve 22 and the delivery pipe 60.

[0060] Figure 3 The diagram shows the shifts in values ​​when a fuel leak occurs in the fuel passage further downstream of the second shut-off valve 22. Figure 3 (A) indicates the progression of the internal combustion engine's operating state. Figure 3 (B) indicates the shift in the energized state of the second shut-off valve 22. Figure 3 (C) indicates the progression of fuel temperature THF. Figure 3 (D) indicates the shift of the third pressure P3. Additionally, Figure 3 (D) shows the double-dotted line L1, which represents the shift of the third pressure P3 when no fuel leak occurs.

[0061] like Figure 3 As shown, at time t1, the processing circuit 110 determines whether the engine stop is complete. For example, if a predetermined time has elapsed since the engine speed NE becomes "0" during the operation that accompanied the engine stop request, the processing circuit 110 determines that the engine stop is complete.

[0062] As the engine stops, the processing circuit 110 stops energizing the second shut-off valve 22, thus de-energizing it and closing the second shut-off valve 22, which has now been closed.

[0063] In the event of fuel leakage in the fuel passage downstream of the second shut-off valve 22, the third pressure P3 gradually decreases after the second shut-off valve 22 closes. Furthermore, the fuel temperature THF varies due to heat from the internal combustion engine 10 or the influence of driving airflow.

[0064] If an engine start request is generated at time t2, the processing circuit 110 begins to energize the second shut-off valve 22. If the first valve 210 is opened by energizing the second shut-off valve 22, fuel flows from the pressure chamber 227 toward the outlet port 203, and therefore the third pressure P3 gradually increases toward the aforementioned second pressure P2.

[0065] As the third pressure P3 increases, the pressure difference ΔP between the aforementioned second pressure P2 (which is the pressure on the upstream side of the second shut-off valve 22) and the third pressure P3 (which is the pressure on the downstream side of the second shut-off valve 22) decreases.

[0066] Then, at time t3, when the pressure difference ΔP becomes below the predetermined value mentioned above, the second valve 220 opens and becomes fully open.

[0067] At the aforementioned time t2, the processing circuit 110 performs the process of acquiring the fuel temperature THF at the time when the second shut-off valve 22 is energized as the fuel temperature THFs at the start of energization.

[0068] At time t3, the processing circuit 110 performs the following processing: acquiring the valve opening time Tvo required from the start of energizing the second shut-off valve 22 until the second valve 220 is fully open. Furthermore, if the second valve 220 is fully open, the current flowing through the solenoid coil 240 will temporarily decrease. Therefore, upon detecting this temporary decrease in current, the processing circuit 110 determines that the opening of the second valve 220 has been completed. Moreover, if the second valve 220 is fully open, the third pressure P3 is maintained at approximately the same level as the second pressure P2. Therefore, upon detecting this behavior of the third pressure P3, the processing circuit 110 can determine that the opening of the second valve 220 has been completed.

[0069] Furthermore, at the aforementioned time t3, the processing circuit 110 performs the process of acquiring the third pressure P3 at the time when the second valve 220 is completed as the valve opening completion pressure P3f.

[0070] When the processing circuit 110 acquires the fuel temperature THFs at the start of energization, the valve opening time Tvo, and the valve opening completion pressure P3f, it performs a calculation based on these values ​​to determine the third pressure P3 at the start of energization of the second shut-off valve 22, i.e., the energization start pressure P3s. This calculation of the energization start pressure P3s is performed using pre-set mapping data or a calculation formula.

[0071] When calculating the pressure P3s at the start of energization, the processing circuit 110 performs the calculation of the difference ΔP3 obtained by subtracting the pressure P3s at the start of energization from the pressure P3f at the completion of valve opening.

[0072] When calculating the difference ΔP3, the processing circuit 110 performs a process to calculate the amount of fuel leakage N in the fuel passage downstream of the second shut-off valve 22 based on the difference ΔP3 and the valve opening time Tvo. The processing circuit 110 calculates the leakage amount N such that the larger the difference ΔP3, the larger the value of leakage amount N. Furthermore, the processing circuit 110 calculates the leakage amount N such that the longer the valve opening time Tvo, the larger the value of leakage amount N. This calculation of leakage amount N is performed using pre-set mapping data or a calculation formula.

[0073] When calculating the leakage amount N, the processing circuit 110 performs a determination process to determine whether fuel is leaking based on the leakage amount N. For example, as this determination process, the processing circuit 110 performs the following process: If the leakage amount N is above a predetermined threshold Nref, it is determined that there is a fuel leak; conversely, if the leakage amount N is less than the threshold Nref, it is determined that there is no fuel leak. Furthermore, a calibration value for appropriately determining a fuel leak is preset in the threshold Nref.

[0074] <The function and effects of this implementation method>

[0075] (1) If fuel leakage occurs in the fuel passage downstream of the second shut-off valve 22, the third pressure P3 gradually decreases after the second shut-off valve 22 is closed. Therefore, the fuel pressure in this fuel passage, i.e., the third pressure P3, when the second shut-off valve 22 is energized again, is lower than the fuel pressure in the fuel passage upstream of the second shut-off valve 22, i.e., the second pressure P2. Therefore, the difference between the third pressure P3 when the second shut-off valve 22 is energized and the third pressure P3 when the second valve 220 is opened, i.e., the difference ΔP3, increases as the amount of fuel leakage increases. Furthermore, the valve opening time Tvo required from the start of energizing the second shut-off valve 22 to the completion of opening the second valve 220 also increases as the amount of fuel leakage increases. Thus, the difference ΔP3 and the valve opening time Tvo are values ​​related to the amount of fuel leakage N in the fuel passage downstream of the second shut-off valve 22.

[0076] Therefore, the processing circuit 110 of this embodiment calculates the fuel leakage amount N based on the valve opening time Tvo and the difference ΔP3. Then, it determines whether there is a fuel leak based on the calculated leakage amount N. Therefore, it is possible to appropriately detect the leakage of hydrogen gas as fuel.

[0077] (2) The diameter of the fuel passage, i.e., the outlet port 203, opened and closed by the second valve 220 is set such that the velocity of the fuel flowing in the outlet port 203 is the speed of sound, thus the flow velocity of the fuel flowing in the outlet port 203 becomes constant. In this case, the fuel pressure in the fuel passage downstream of the second shut-off valve 22, and the fuel pressure at the start of energization of the second shut-off valve 22, is related to the following values: that is, the fuel temperature THF at the start of energization (i.e., the fuel temperature THFs at the start of energization), the valve opening time Tvo, and the third pressure P3 at the end of opening the second shut-off valve 22 (i.e., the valve opening end pressure P3f). Therefore, in this embodiment, the pressure P3s at the start of energization is calculated based on these fuel temperatures THFs at the start of energization, the valve opening time Tvo, and the valve opening end pressure P3f. Therefore, the fuel pressure when the second shut-off valve 22 is energized, i.e., the pressure P3s at the start of energization, can be calculated.

[0078] (3) In the event of a fuel leak from the fuel passage, the fuel pressure inside the fuel passage gradually decreases when the fuel passage is sealed. Therefore, hydrogen leakage can be detected based on this change in fuel pressure. However, if the fuel temperature inside the fuel passage rises due to heat transferred from the internal combustion engine, the fuel density changes, affecting the change in fuel pressure, and thus hydrogen leakage may not be properly detected. In this regard, in this embodiment, the presence or absence of fuel leakage is determined based on the fuel pressure after the second shut-off valve 22 is energized or the aforementioned valve opening time Tvo. Therefore, false detection of leakage caused by heat transferred from the internal combustion engine can be suppressed.

[0079] <Example of Change>

[0080] Furthermore, the above-described implementation method can be modified as follows. The above-described implementation method and the following modifications can be combined with each other within a technically compatible scope.

[0081] • Let’s assume that the pressure P3s at the start of energization is calculated, but the value detected by the third pressure sensor 83 when the second shut-off valve 22 is energized can also be substituted into the pressure P3s at the start of energization.

[0082] • The structure of the second shut-off valve 22 shown in the above embodiment is an example. In short, any solenoid valve having a first valve body and a second valve body is acceptable. The first valve body is opened by energizing it, thereby allowing fuel to flow from the upstream side to the downstream side of the solenoid valve. The second valve body is opened only when the pressure difference between the upstream side of the solenoid valve and the downstream side of the solenoid valve is below a predetermined value.

[0083] Symbol Explanation

[0084] 10-Internal combustion engine, 10a-Cylinder, 11-Intake passage, 12-Throttle valve, 15-Fuel injection valve, 20-Canister, 21-First shut-off valve, 22-Second shut-off valve, 27-Accelerator pedal, 30-Pressure relief valve, 40-Fuel piping, 60-Delivery pipe, 71-Throttle position sensor, 72-Speed ​​sensor, 73-Air flow meter, 74-Crankshaft angle sensor, 81-First pressure sensor, 82-Second pressure sensor, 83-Third pressure sensor, 84-Temperature sensor, 100-Control device, 110-Processing circuit, 200-Housing, 201-Inlet port, 202-First chamber, 203- Outlet port, 204-Second valve seat, 210-First valve, 211-Plunger, 212-Protrusion, 213-First sealing element, 214-Pin, 215-Spring, 220-Second valve, 221-Hole, 222-First fuel passage, 223-First valve seat, 224-Second sealing element, 225-Elongated hole, 226-Communication passage, 227-Pressure chamber, 228-End face, 229-Wall surface, 230-Stator, 240-Electromagnetic coil, 250-Cage, 251-Cylinder, 253-Restriction part, 255-Second chamber, 257-Third chamber, 280-End cap, 300-Fuel supply device.

Claims

1. A fuel supply device for an internal combustion engine, comprising: a tank for storing hydrogen as fuel for the internal combustion engine; a fuel injection valve for supplying the fuel to a cylinder; and a fuel passage for supplying the fuel in the tank to the fuel injection valve; The internal combustion engine's fuel supply device is characterized by: a solenoid valve disposed in the fuel passage and opening and closing the fuel passage; a pressure sensor that detects fuel pressure in the fuel passage downstream of the solenoid valve in the fuel flow direction; and a control device comprising a processing circuit that performs a process to determine whether there is fuel leakage in the downstream fuel passage. The solenoid valve has the following characteristics: The first valve body opens when energized, thereby allowing fuel to flow from the upstream side to the downstream side of the solenoid valve; and the second valve body opens when the pressure difference between the upstream and downstream sides of the solenoid valve falls below a predetermined value. The processing circuit performs the following processing: Obtain the valve opening time required from the start of energizing the solenoid valve to the end of the valve opening of the second valve body; Calculate the difference between the fuel pressure when the solenoid valve is energized and the fuel pressure when the second valve body is closed. The amount of fuel leakage in the fuel passage on the downstream side is calculated based on the valve opening time and the difference. and The presence or absence of the fuel leak is determined based on the amount of leakage.

2. The fuel supply device for an internal combustion engine according to claim 1, characterized in that, have: A temperature sensor detects the fuel temperature in the fuel passage located downstream of the solenoid valve when viewed in the direction of fuel flow. The diameter of the fuel passage within the solenoid valve, which is opened and closed by the second valve body, is set such that the speed of the fuel flowing in that fuel passage is equal to the speed of sound. The processing circuit performs the following processing: The fuel pressure at the start of energizing the solenoid valve is calculated based on the fuel temperature when the solenoid valve is first energized, the valve opening time, and the fuel pressure at the end of the valve opening of the second valve body.

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