Fuel supply system for internal combustion engines

Abstract

To properly detect hydrogen gas leaks. [Solution] The control device 100 of the fuel supply device 300 includes a processing circuit 110 that performs a process to determine whether or not there is a fuel leak in the fuel passage downstream of the second shut-off valve 22. The second shut-off valve 22 has a first valve body that, when opened by energization, allows fuel to flow from the upstream side to the downstream side of the second shut-off valve 22, and a second valve body that opens when the pressure difference between the pressure upstream of the second shut-off valve 22 and the pressure downstream of the second shut-off valve 22 falls below a predetermined value. The processing circuit 110 performs a process to acquire the opening time required from the start of energization of the second shut-off valve 22 until the opening of the second valve body is completed, a process to calculate the difference between the fuel pressure when energization of the second shut-off valve 22 is started and the fuel pressure when the opening of the second valve body is completed, a process to calculate the amount of fuel leaking in the fuel passage downstream of the second shut-off valve 22 based on the opening time and the difference, and a process to determine whether or not there is a fuel leak based on the calculated amount of leak.

Description

Technical Field

[0001] The present invention relates to a fuel supply device for an internal combustion engine.

Background Art

[0002] Internal combustion engines using hydrogen gas as fuel are known. When such an internal combustion engine is stopped, fuel leakage occurs if, for example, poor closing of a fuel injection valve occurs. Therefore, it is necessary to detect fuel leakage from a fuel passage including the fuel injection valve. For this reason, for example, in the internal combustion engine described in Patent Document 1, a hydrogen detection sensor for detecting hydrogen gas leaking from a fuel system is provided in an upper cover mounted on a head cover.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] When detecting fuel leakage using the above hydrogen detection sensor, there is a possibility that hydrogen gas leakage cannot be appropriately detected unless the hydrogen gas detection unit of the hydrogen detection sensor is installed at an appropriate position.

Means for Solving the Problem

[0005] A fuel supply system for an internal combustion engine that solves the above problems includes a tank for storing hydrogen gas, which is the fuel for the internal combustion engine; a fuel injection valve for supplying the fuel to the cylinders; a fuel passage for supplying the fuel in the tank to the fuel injection valve; a solenoid valve provided in the fuel passage for opening and closing the fuel passage; a pressure sensor for detecting the fuel pressure in the fuel passage downstream of the solenoid valve when viewed in the direction of fuel flow; and a control device equipped with a processing circuit that performs a process to determine whether or not there is a fuel leak in the downstream fuel passage. The solenoid valve has a first valve body that, when energized, opens to allow the fuel to flow from the upstream side to the downstream side of the solenoid valve; and a second valve body that opens when the pressure difference between the pressure upstream of the solenoid valve and the pressure downstream of the solenoid valve falls below a predetermined value. The processing circuit performs the following processes: obtaining the valve opening time required from the start of energizing the solenoid valve until the opening of the second valve body is completed; calculating the difference between the fuel pressure when energizing the solenoid valve is started and the fuel pressure when the opening of the second valve body is completed; calculating the amount of fuel leakage in the downstream fuel passage based on the valve opening time and the difference; and determining whether or not there is fuel leakage based on the amount of leakage. [Effects of the Invention]

[0006] This internal combustion engine's fuel supply system can properly detect hydrogen gas leaks. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing an internal combustion engine, fuel supply system, and control device to which a solenoid valve control device in one embodiment is applied. [Figure 2] Figure 2 is a cross-sectional view showing the structure of the second shut-off valve in the same embodiment. [Figure 3] Figure 3 is a timing chart showing the changes in each value when there is a hydrogen gas leak, where (A) shows the changes in the operating state of the internal combustion engine, (B) shows the changes in the energization state of the second shut-off valve, (C) shows the changes in fuel temperature, and (D) shows the changes in the third pressure. [Modes for carrying out the invention]

[0008] Below, one embodiment of a fuel supply system for an internal combustion engine will be described with reference to Figures 1 to 3. <Configuration of the fuel supply system for an internal combustion engine> The internal combustion engine 10 shown in Figure 1 is mounted on a vehicle and uses hydrogen gas, a fluid gaseous fuel, as its fuel. The vehicle is, for example, a hybrid vehicle equipped with the internal combustion engine 10 and an electric motor as prime movers. In such a hybrid vehicle, the internal combustion engine 10 is operated intermittently.

[0009] The intake passage 11 of the internal combustion engine 10 is provided with a throttle valve 12 for adjusting the amount of intake air. The fuel supply system 300 provided by the internal combustion engine 10 includes a fuel injection valve 15, a tank 20, fuel piping 40, a first shut-off valve 21, a second shut-off valve 22, a pressure reducing valve 30, and a delivery pipe 60.

[0010] The fuel injector 15 supplies fuel to the cylinder 10a of the internal combustion engine 10. The tank 20 stores hydrogen gas, a gaseous fuel, in a compressed state. The fuel piping 40 connects the tank 20 to the delivery pipe 60. The fuel injector 15 is connected to the delivery pipe 60. The fuel piping 40 and the delivery pipe 60 are fuel passages connecting the tank 20 and the fuel injector 15. The hydrogen gas stored in the tank 20 is supplied to the fuel injector 15 via the fuel piping 40 and the delivery pipe 60.

[0011] The fuel piping 40 has a first shut-off valve 21, a pressure reducing valve 30, and a second shut-off valve 22 arranged in order in the direction of fuel flow. In the following, 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."

[0012] The first shut-off valve 21 is a solenoid valve and is located near the outlet of the tank 20. When the first shut-off valve 21 is open, fuel is supplied from the tank 20 to the fuel piping 40. When the first shut-off valve 21 is closed, the fuel supply from the tank 20 to the fuel piping 40 is stopped.

[0013] The pressure reducing valve 30 is a valve that reduces the fuel pressure, which is the fuel pressure of hydrogen gas stored in the tank 20 under high pressure, to a specified pressure (for example, about 4 MPa) and supplies it to the fuel injection valve 15.

[0014] The second shut-off valve 22 is a solenoid valve and is located in the fuel piping 40 near the delivery pipe 60. When the second shut-off valve 22 is open due to energization, fuel is supplied to the delivery pipe 60. When the second shut-off valve 22 is closed due to de-energization, the fuel supply to the delivery pipe 60 is stopped.

[0015] The first shut-off valve 21 and the second shut-off valve 22 are closed when the internal combustion engine 10 is stopped. On the other hand, the first shut-off valve 21 and the second shut-off valve 22 are basically open when the internal combustion engine 10 is running.

[0016] A first pressure sensor 81, installed in the fuel piping 40 between the first shut-off valve 21 and the pressure reducing valve 30, detects a first pressure P1, which is the fuel pressure in the fuel piping 40 between the first shut-off valve 21 and the pressure reducing valve 30.

[0017] A second pressure sensor 82, installed in the fuel piping 40 between the pressure reducing valve 30 and the second shut-off valve 22, detects the second pressure P2, which is the fuel pressure in the fuel piping 40 between the pressure reducing valve 30 and the second shut-off valve 22.

[0018] A third pressure sensor 83 installed in the delivery pipe 60 detects the third pressure P3, which is the fuel pressure in the delivery pipe 60. The third pressure sensor 83 is a pressure sensor that detects the third pressure P3, which is the fuel pressure in the fuel passage downstream of the second shut-off valve 22 when viewed in the direction of fuel flow.

[0019] A temperature sensor 84 provided on the delivery pipe 60 detects a fuel temperature THF, which is the temperature of fuel inside the delivery pipe 60. The temperature sensor 84 is a pressure sensor that detects fuel pressure in a fuel passage downstream of a solenoid valve when viewed in the fuel flow direction.

[0020] The control device 100 implements various controls such as fuel injection for the internal combustion engine 10 by controlling various controlled objects including a throttle valve 12, a fuel injection valve 15, a first cutoff valve 21, and a second cutoff valve 22. This control device 100 includes a processing circuit 110 configured by a CPU and a memory. In the processing circuit 110, various controls are implemented when a program stored in the memory is executed by the CPU.

[0021] The control device 100 refers to various values necessary for controlling the internal combustion engine 10. For example, the control device 100 refers to detection values from a first pressure sensor 81, a second pressure sensor 82, a third pressure sensor 83, and the temperature sensor 84. The control device 100 also refers to a detection signal from an accelerator position sensor 71 that detects an accelerator operation amount ACCP, which is the operation amount of an accelerator pedal 27 operated by a driver of a vehicle equipped with the internal combustion engine 10. The control device 100 also refers to a detection signal from a vehicle speed sensor 72 that detects a vehicle speed SP of the vehicle equipped with the internal combustion engine 10. Furthermore, the control device 100 refers to a detection signal from an air flow meter 73 that detects an intake air amount GA of the internal combustion engine 10, and a detection signal Scr from a crank angle sensor 74 that detects a rotation angle of a crankshaft of the internal combustion engine 10.

[0022] The control device 100 calculates an engine rotational speed NE based on the detection signal Scr from the crank angle sensor 74. The control device 100 also calculates an engine load factor KL based on the engine rotational speed NE and the intake air amount GA. The engine load factor KL represents the ratio of a current cylinder inflow air amount to a cylinder inflow air amount when the internal combustion engine 10 is steadily operated at full load at the current engine rotational speed NE. Note that the cylinder inflow air amount is the amount of air that flows into each cylinder during an intake stroke.

[0023] When a predetermined stop condition is met and an engine stop request is generated, the control device 100 stops the operation of the internal combustion engine 10. Furthermore, when a predetermined start condition is met and an engine start request is generated, the control device 100 starts the internal combustion engine 10, which is currently stopped. In this way, the internal combustion engine 10 repeatedly undergoes intermittent stopping and starting.

[0024] <Structure of the second shutoff valve> Figure 3 shows the structure of the second shut-off valve 22. In the following, the direction along the central axis L of the plunger 211 of the second shut-off valve 22 is referred to as the axial direction. The direction perpendicular to the axial direction is referred to as the radial direction.

[0025] The second shut-off valve 22 includes a housing 200, a stator 230, an electromagnetic coil 240, a first valve 210, a holder 250, a second valve 220, and the like. The housing 200 includes an inlet port 201 to which a fuel pipe 40 connected to a pressure reducing valve 30 is connected, and an outlet port 203 to which a fuel pipe 40 connected to a delivery pipe 60 is connected.

[0026] The inlet port 201 and the outlet port 203 are in communication via the first chamber 202, which is a space formed within the housing 200. The stator 230 is cylindrical and is located inside the housing 200.

[0027] The electromagnetic coil 240 is located on the outer circumference of the stator 230. The electromagnetic coil 240 opens the valve body when energized. The drive circuit that drives the electromagnetic coil 240 is connected to the control device 100.

[0028] The first valve body, the first valve 210, includes 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 as the plunger 211 moves.

[0029] One end of the plunger 211 is a protruding portion 212 that extends from the stator 230. The tip of the protruding portion 212 is provided with the first sealing member 213. The protruding portion 212 is also equipped with a radially extending pin 214. Both ends of the pin 214 protrude from the outer circumferential surface of the protruding portion 212.

[0030] The holder 250 has a cylindrical portion 251 that is coaxial with the central axis L. The inner circumferential surface of the cylindrical portion 251 is spaced apart from the outer circumferential surface of the protrusion 212. The second valve body, the second valve 220, is slidably housed on the inner circumferential surface of the cylindrical portion 251. The second valve 220 has a hole 221 through which the outer circumferential surface of the projection 212 of the first valve 210 slides. The second valve 220 has an elongated hole 225 into which the pin 214 is inserted and which allows the pin 214 to move in the axial direction.

[0031] The tip of the second valve 220 has a first fuel passage 222 that extends in the axial direction. The first fuel passage 222 is connected to the outlet port 203 which constitutes the second fuel passage. The outlet port 203 is a fuel passage with a larger flow path cross-sectional area than the first fuel passage 222.

[0032] The tip of the second valve 220 is provided with a second sealing member 224 that opens and closes the outlet port 203. More specifically, the second sealing member 224 opens and closes a second valve seat 204 provided at one end of the outlet port 203. The outlet port 203 is a fuel passage that is opened and closed by the second valve 220. The diameter of the outlet port 203 is set to such a size that the velocity of the fuel flowing through the outlet port 203 is equal to the speed of sound.

[0033] A first valve seat 223 is formed at the tip of the second valve 220, in which the first fuel passage 222 is formed, and protrudes toward the protruding portion 212. The first fuel passage 222 is opened and closed by the opening and closing of the first valve seat 223 by the first sealing member 213. This first fuel passage 222 is a communication passage that connects the flow path upstream of the second valve 220, which is the second valve body, with the flow path downstream of the second valve 220. The flow path upstream of the second valve 220 is the pressure chamber 227, the communication passage 226, the first chamber 202, and the inlet port 201, which will be described later. The flow path downstream of the second valve 220 is the outlet port 203. The first valve 210 is a first valve body that opens prior to the opening of the second valve 220 and opens and closes the first fuel passage 222.

[0034] In the hole 221, the space enclosed by the wall surface around the first valve seat 223 and the tip surface of the projection 212 forms a pressure chamber 227 through which pressure acts to bias the second valve 220 in the closing direction. This pressure chamber 227 is connected to the first chamber 202 via a connecting passage 226.

[0035] A second chamber 255 is formed on the inner circumferential surface side of the cylindrical portion 251 of the holder 250, which is a space for securing the axial stroke amount of the second valve 220. The end face 228 of the second valve 220, which is opposite to the side where the second sealing member 224 is disposed, and the restricting portion 253 of the holder 250, which is the surface facing the end face 228, come into contact with each other when the second valve 220 is fully open. By maintaining this contact between the end face 228 and the restricting portion 253, the position of the valve body becomes stable when the second valve 220 is fully open.

[0036] An end cap 280 is provided inside the stator 230, at the end opposite to the side into which the plunger 211 is inserted, to close that end. A third chamber 257, which is a space, is formed between the end cap 280 and the plunger 211. A spring 215 is also provided between the end cap 280 and the plunger 211 to bias the plunger 211 in a direction away from the end cap 280.

[0037] <Opening and closing operation of the second shut-off valve> When the electromagnetic coil 240 is energized, the plunger 211 is pulled into the stator 230, causing the first valve 210 to move in a direction that separates the first sealing member 213 from the first valve seat 223, thereby opening the first valve 210. When the first sealing member 213 separates from the first valve seat 223, the fuel that has flowed in from the inlet port 201 flows into the outlet port 203 via the first chamber 202, the communication passage 226, the pressure chamber 227, and the first fuel passage 222.

[0038] Then, as the first valve 210 moves in a direction that separates the first sealing member 213 from the first valve seat 223, the pin 214 of the first valve 210 strikes the wall surface 229 located in the axial direction of the elongated hole 225 of the second valve 220, in the direction of the opening of the first valve 210. As a result, an opening force Fop acts on the second valve 220 in the same direction as the movement 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 direction that opens the second valve 220.

[0039] When the first valve 210 opens, the pressure chamber 227 and the outlet port 203 are connected, so the pressure difference ΔP between the pressure chamber 227 and the outlet port 203 decreases. Therefore, the resistance force Fcl, which is the force resisting the opening of the second valve 220, decreases. The resistance force Fcl includes the force acting on the second valve 220 in the closing direction, as well as the sliding resistance of the second valve 220 and the holder 250. Furthermore, the force acting on the second valve 220 in the closing direction includes the differential pressure load generated by the pressure difference ΔP between the pressure chamber 227 and the outlet port 203, and the biasing force of the spring 215.

[0040] Then, when the valve opening force Fop becomes greater than the resistance force Fcl, the second valve 220 moves in a direction that separates the second sealing member 224 from the second valve seat 204, thereby opening the second valve 220. When the second sealing member 224 separates from the second valve seat 204, the fuel that has flowed in from the inlet port 201 flows mainly through the first chamber 202 to the outlet port 203.

[0041] When the second valve 220 is fully open, the end face 228 and the restricting portion 253 come into contact, stopping the axial movement of the second valve 220. The fuel that flows into the outlet port 203 is sent to the fuel injection valve 15 via the fuel piping 40 and the delivery pipe 60.

[0042] When the current to the electromagnetic coil 240 is cut off, the biasing force of the spring 215 causes the first valve 210 to move in a direction that causes the first sealing member 213 to strike the first valve seat 223. This causes the first valve 210 to close.

[0043] When the first sealing member 213 contacts the first valve seat 223, the biasing force of the spring 215 acts on the second valve 220. As a result, the second valve 220 moves in the direction in which the second sealing member 224 contacts the second valve seat 204. This causes the second valve 220 to close.

[0044] In this way, the second shut-off valve 22 opens the second valve 220, which opens and closes the outlet port 203, having a larger flow path cross-sectional area than the first fuel passage 222, using the pressure in the pressure chamber 227. That is, when the pressure difference ΔP between the pressure chamber 227 and the outlet port 203, which is the pressure difference between the upstream and downstream sides of the second shut-off valve 22, becomes small and falls below a predetermined value, the second valve 220 opens. Therefore, compared to the case where the magnetic force of the electromagnetic coil is directly used to open the second valve 220, the magnetic force required to open the valve can be reduced. Consequently, for example, the electromagnetic coil 240 can be miniaturized. In this embodiment, for example, the attractive force of the electromagnetic coil 240 is set so that the second valve 220 opens when the above pressure difference ΔP becomes approximately "0". In other words, the attractive force is set as the force that opposes the sliding resistance between the second valve 220 and the holder 250 and the biasing force of the spring 215, which are part of the above-mentioned resistance force Fcl.

[0045] <Regarding hydrogen gas leak detection> The processing circuit 110 determines whether or not there is a fuel leak in the fuel passage downstream of the second shut-off valve 22 when viewed in the direction of fuel flow by executing the process described below. Fuel leaks in the fuel passage downstream of the second shut-off valve 22 include, for example, fuel leaks from the fuel injector 15 due to a malfunction of the fuel injector 15, or fuel leaks from the delivery pipe 60. Fuel leaks in the fuel passage downstream of the second shut-off valve 22 also include, for example, fuel leaks from the fuel piping 40 connecting the second shut-off valve 22 and the delivery pipe 60.

[0046] Figure 3 shows the changes in various values ​​when fuel leakage occurs in the fuel passage downstream of the second shut-off valve 22. Figure 3(A) shows the changes in the operating state of the internal combustion engine. Figure 3(B) shows the changes in the energization state of the second shut-off valve 22. Figure 3(C) shows the changes in the fuel temperature THF. Figure 3(D) shows the changes in the third pressure P3. Note that the dashed line L1 shown in Figure 3(D) shows the changes in the third pressure P3 when no fuel leakage occurs.

[0047] As shown in Figure 3, at time t1, the processing circuit 110 determines that the engine shutdown is complete. For example, the processing circuit 110 determines that the engine shutdown is complete when the engine rotation speed NE has been at "0" for a predetermined period of time due to the shutdown in response to the engine shutdown request.

[0048] As a result of this engine shutdown, the processing circuit 110 stops the power supply to the second shut-off valve 22, thereby de-energizing it and closing the second shut-off valve 22, which had been open until then. If a fuel leak occurs in the fuel passage downstream of the second shut-off valve 22, the third pressure P3 will gradually decrease after the second shut-off valve 22 closes. In addition, the fuel temperature THF will fluctuate due to the effects of heat received from the internal combustion engine 10 and airflow during driving.

[0049] When an engine start request occurs at time t2, the processing circuit 110 starts energizing the second shut-off valve 22. When the first valve 210 opens due to the energization of the second shut-off valve 22, fuel flows from the pressure chamber 227 towards the outlet port 203, and the third pressure P3 gradually increases toward the second pressure P2.

[0050] As the third pressure P3 increases, the pressure difference ΔP between the second pressure P2, which is the pressure upstream of the second shut-off valve 22, and the third pressure P3, which is the pressure downstream of the second shut-off valve 22, decreases.

[0051] Then, at time t3, when the pressure difference ΔP falls below the predetermined value mentioned above, the second valve 220 opens and becomes fully open. At the above time t2, the processing circuit 110 executes a process to acquire the fuel temperature THF at the start of energization as the fuel temperature THFs when energization is started on the second shut-off valve 22.

[0052] At the above time t3, the processing circuit 110 executes a process to obtain the valve opening time Tvo, which is the time required from the start of energizing the second shut-off valve 22 until the second valve 220 is fully opened. When the second valve 220 is fully open, the current flowing through the electromagnetic coil 240 temporarily decreases. Therefore, if such a temporary decrease in current is detected, the processing circuit 110 determines that the opening of the second valve 220 is complete. Also, when the second valve 220 is fully open, the third pressure P3 is maintained at approximately equality with the second pressure P2. Therefore, if such behavior of the third pressure P3 is detected, the processing circuit 110 may determine that the opening of the second valve 220 is complete.

[0053] Furthermore, at the above time t3, the processing circuit 110 executes a process to acquire the third pressure P3, which occurs when the opening of the second valve 220 is completed, as the valve opening completion pressure P3f. The processing circuit 110 obtains the fuel temperature THFs at the start of energization, the valve opening time Tvo, and the valve opening completion pressure P3f. Based on these values, it performs a process to calculate the third pressure P3, which is the energization start pressure P3s, when energization is started to the second shut-off valve 22. This calculation of the energization start pressure P3s is performed using pre-set map data or a calculation formula.

[0054] The processing circuit 110 calculates the initial energization pressure P3s, and then performs a process to calculate the difference ΔP3, which is the value obtained by subtracting the initial energization pressure P3s from the valve opening completion pressure P3f. The processing circuit 110 calculates the difference ΔP3 and, based on the difference ΔP3 and the valve opening time Tvo, performs a process to calculate the amount of fuel leakage N in the fuel passage downstream of the second shut-off valve 22. The processing circuit 110 calculates the amount of leakage N such that the larger the difference ΔP3, the larger the value of the leakage amount N. Furthermore, the processing circuit 110 calculates the amount of leakage N such that the longer the valve opening time Tvo, the larger the value of the leakage amount N. This calculation of the amount of leakage N is performed using pre-set map data or a calculation formula.

[0055] When the processing circuit 110 calculates the amount of leakage N, it performs a determination process to determine whether or not there is a fuel leak based on the amount of leakage N. For example, as part of this determination process, the processing circuit 110 performs the following: The processing circuit 110 determines that there is a fuel leak if the amount of leakage N is greater than or equal to a predetermined threshold Nref, while determining that there is no fuel leak if the amount of leakage N is less than the threshold Nref. The threshold Nref is pre-set to a suitable value for appropriately determining whether or not there is a fuel leak.

[0056] <Operation and Effects of This Embodiment> (1) If fuel leakage occurs in the fuel passage downstream of the second shut-off valve 22, the third pressure P3 after the second shut-off valve 22 is closed will gradually decrease. Therefore, the third pressure P3, which is the fuel pressure in the same fuel passage when the second shut-off valve 22 is energized again, is lower than the second pressure P2, which is the fuel pressure in the fuel passage upstream of the second shut-off valve 22. Consequently, the difference ΔP3, which is 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 fully opened, becomes larger as the amount of fuel leakage increases. Also, the valve opening time Tvo, which is required from the start of energizing the second shut-off valve 22 until the second valve 220 is fully opened, becomes longer as the amount of fuel leakage increases. Thus, the difference ΔP3 and the valve opening time Tvo are values ​​that correlate with the amount of fuel leakage N in the fuel passage downstream of the second shut-off valve 22.

[0057] Therefore, the processing circuit 110 of this embodiment calculates the amount of fuel leakage N based on the valve opening time Tvo and the difference ΔP3. Then, it determines whether or not there is a fuel leak based on the calculated amount of leakage N. Accordingly, it is possible to appropriately detect leaks of hydrogen gas, which is the fuel.

[0058] (2) The diameter of the outlet port 203, which is a fuel passage opened and closed by the second valve 220, is set to a size such that the velocity of the fuel flowing through the outlet port 203 is equal to the speed of sound, so the flow velocity of the fuel flowing through the outlet port 203 is constant. In this case, the fuel pressure in the fuel passage downstream of the second shut-off valve 22, which is the fuel pressure when the second shut-off valve 22 is energized, is correlated with the following values: the fuel temperature THFs at the start of energization, which is the fuel temperature THFs at the start of energization when the second shut-off valve 22 is energized, the valve opening time Tvo, and the valve opening completion pressure P3f, which is the third pressure P3 when the opening of the second shut-off valve 22 is completed. In this embodiment, the fuel temperature THFs at the start of energization, the valve opening time Tvo, and the valve opening completion pressure P3f are used to calculate the fuel temperature THFs at the start of energization, the valve opening time Tvo, and the valve opening completion pressure P3f.

[0059] (3) If there is a fuel leak from the fuel passage, the fuel pressure in the fuel passage will gradually decrease when the fuel passage is sealed. Therefore, it is possible to detect hydrogen gas leaks based on such changes in fuel pressure. However, if the fuel temperature in the fuel passage rises due to the heat transmitted from the internal combustion engine, the density of the fuel will change and affect the change in fuel pressure, which may prevent proper detection of hydrogen gas leaks. In this embodiment, the presence or absence of a fuel leak is determined based on the fuel pressure after energization of the second shut-off valve 22 and the valve opening time Tvo. Therefore, false detection of leaks due to heat transmitted from the internal combustion engine can be suppressed.

[0060] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0061] • Although the above calculation method was used to determine the initial energization pressure P3s, the value detected by the third pressure sensor 83 when energization is started to the second shut-off valve 22 may be substituted for the initial energization pressure P3s.

[0062] The structure of the second shut-off valve 22 shown in the above embodiment is just one example. Essentially, any solenoid valve will suffice, having a first valve body that, when energized, opens to allow fuel to flow from the upstream to the downstream side of the solenoid valve, and a second valve body that opens when the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the solenoid valve falls below a predetermined value. [Explanation of Symbols]

[0063] 10...Internal combustion engine 10a...Cylinder 11...Intake passage 12...Throttle valve 15...Fuel injector 20...Tank 21...First shut-off valve 22...Second shut-off valve 27...Accelerator pedal 30...Pressure reducing valve 40...Fuel piping 60...Delivery pipe 71...Accelerator position sensor 72...Speed ​​sensor 73...Air flow meter 74...Crank 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 seal member 214...Pin 215...Spring 220...Second valve 221…Hole 222…First fuel passage 223…First valve seat 224…Second sealing member 225…Slotted hole 226…Connecting passage 227…Pressure chamber 228…End face 229…Wall surface 230…Stator 240…Electromagnetic coil 250…Holder 251…Cylindrical section 253…Regulating section 255…Second chamber 257…Third chamber 280…End cap 300…Fuel supply device

Claims

1. A fuel supply system for an internal combustion engine, comprising: a tank for storing hydrogen gas, which is the fuel for the internal combustion engine; a fuel injection valve for supplying the fuel to the cylinders; a fuel passage for supplying the fuel from the tank to the fuel injection valve; a solenoid valve provided in the fuel passage 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 equipped with a processing circuit that performs a process to determine whether or not there is a fuel leak in the downstream fuel passage, The solenoid valve has a first valve body that, when energized, opens to allow the fuel to flow from the upstream side to the downstream side of the solenoid valve, and a second valve body that opens when the pressure difference between the pressure on the upstream side of the solenoid valve and the pressure on the downstream side of the solenoid valve falls below a predetermined value. The aforementioned processing circuit is A process to obtain the valve opening time required from the start of energizing the solenoid valve until the opening of the second valve body is completed, A process for calculating the difference between the fuel pressure when the solenoid valve is energized and the fuel pressure when the second valve body is fully opened, A process for calculating the amount of fuel leakage in the downstream fuel passage based on the valve opening time and the difference, The process of determining whether or not there is a fuel leak based on the amount of leakage is executed. A fuel supply system for an internal combustion engine.

2. It is equipped with a temperature sensor that detects the fuel temperature in the fuel passage downstream of the solenoid valve when viewed in the direction of fuel flow, The diameter of the fuel passage in the solenoid valve, which is opened and closed by the second valve body, is set to a size such that the speed of the fuel flowing through the fuel passage is equal to the speed of sound. The processing circuit performs a process to calculate the fuel pressure at the time the solenoid valve is energized, based on the fuel temperature at the time the solenoid valve is energized, the valve opening time, and the fuel pressure at the time the second valve body has finished opening. A fuel supply device for an internal combustion engine according to claim 1.

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