Gaseous fuel supply device

Abstract

To prevent the temperature of a cylinder injection valve from increasing while allowing an internal combustion engine to operate appropriately.SOLUTION: A gaseous fuel supply device 20 comprises a processing circuit 51 for controlling a cylinder injection valve 21 and a shut-off valve 25. The processing circuit 51 determines an energization time for the cylinder injection valve 21 on the basis of the pressure of gaseous fuel supplied from a supply flow passage 23 to the cylinder injection valve 21. When a temperature of the cylinder injection valve 21 becomes greater than a temperature determination value, the processing circuit 51 starts an opening-closing process of repeatedly bringing the shut-off valve 25 into a closed state and bringing the shut-off valve 25 into an open state. The opening-closing process is a process that brings the shut-off valve 25 into the closed state when the pressure of the gaseous fuel supplied to the cylinder injection valve 21 is greater than a pressure lower limit value and brings the shut-off valve 25 into the open state when the pressure of the gaseous fuel becomes less than or equal to the pressure lower limit value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gaseous fuel supply device that supplies gaseous fuel into cylinders of an internal combustion engine. [Background technology]

[0002] Patent Document 1 discloses an internal combustion engine in which gaseous fuel is injected into a cylinder from a direct injection valve. A combustion chamber is defined within the cylinder in which combustion gas containing the gaseous fuel and air is burned. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-145818 Summary of the Invention [Problem to be solved by the invention]

[0004] The tip of the direct injection valve receives heat from the high-temperature combustion gas in the combustion chamber, and therefore the tip of the direct injection valve becomes extremely hot, which tends to shorten the life of the direct injection valve. [Means for solving the problem]

[0005] A gaseous fuel supply device for solving the above problems is a device applied to an internal combustion engine having a cylinder, and includes: an in-cylinder injection valve that injects gaseous fuel into the cylinder; a storage tank that stores the gaseous fuel; a supply flow path that guides the gaseous fuel in the storage tank to the in-cylinder injection valve; a pressure reducing valve that is provided in the supply flow path and reduces the pressure of the gaseous fuel that flows from the storage tank to the supply flow path; a shutoff valve that is located in the supply flow path downstream of the pressure reducing valve and is switchable between an open state that allows the supply of gaseous fuel to the in-cylinder injection valve and a closed state that stops the supply of gaseous fuel to the in-cylinder injection valve; and a processing circuit that controls the in-cylinder injection valve and the shutoff valve. The processing circuit determines a power supply time for the in-cylinder injection valve based on the pressure of the gaseous fuel supplied from the supply flow path to the in-cylinder injection valve and a required value for the injection amount of the gaseous fuel of the in-cylinder injection valve, and when the temperature of the in-cylinder injection valve becomes higher than a temperature determination value during operation of the internal combustion engine, starts an opening / closing process that repeatedly closes the shutoff valve and opens the shutoff valve. The opening / closing process is a process that closes the shutoff valve when the pressure of the gaseous fuel supplied from the supply flow path to the in-cylinder injection valve is higher than a pressure lower limit value, and opens the shutoff valve when the pressure of the gaseous fuel supplied to the in-cylinder injection valve becomes equal to or lower than the pressure lower limit value.

[0006] In the gaseous fuel supply device, the temperature of the in-cylinder injection valve increases due to the combustion of combustion gas in the cylinder. When the temperature exceeds a temperature determination value, an opening / closing process is initiated. This causes the shutoff valve to close. As a result, the pressure decreases, lengthening the time that the in-cylinder injection valve is energized. This lengthens the time that the gaseous fuel flows through the tip of the in-cylinder injection valve, thereby preventing the temperature of the in-cylinder injection valve from increasing. On the other hand, when the shutoff valve is closed and the pressure falls below a pressure lower limit, the shutoff valve opens. That is, the processing circuit compares the pressure with the pressure lower limit and repeatedly closes and opens the shutoff valve. This prevents the pressure from becoming too low, allowing an appropriate amount of gaseous fuel to be supplied from the in-cylinder injection valve to the cylinder.

[0007] Therefore, the gaseous fuel supply device can prevent the temperature of the direct injection valve from increasing while allowing the internal combustion engine to operate appropriately. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a gaseous fuel supply device according to a first embodiment and an internal combustion engine to which the gaseous fuel supply device is applied. [Figure 2] FIG. 2 is a schematic diagram showing an in-cylinder injection valve included in the gaseous fuel supply device of FIG. [Figure 3] FIG. 3 is a flowchart showing a processing routine executed by the control device provided in the gaseous fuel supply device of FIG. [Figure 4] FIG. 4 is a flowchart showing a processing routine executed by the control device provided in the gaseous fuel supply device of FIG. [Figure 5] FIG. 5 is a flowchart showing a processing routine executed by a control device provided in the gaseous fuel supply device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) A first embodiment of a gaseous fuel supply device will be described below with reference to FIGS. 1 shows a gaseous fuel supply device 20 and an internal combustion engine 10 to which gaseous fuel is supplied from the gaseous fuel supply device 20. The gaseous fuel supply device 20 supplies hydrogen gas as gaseous fuel to the internal combustion engine 10. In other words, the internal combustion engine 10 is a hydrogen gas engine that uses hydrogen gas as fuel.

[0010] <Internal combustion engine> The internal combustion engine 10 has one or more cylinders 11. A piston 12 is housed in the cylinder 11 so that it can freely reciprocate. A combustion chamber 13 is formed in the cylinder 11 by the piston 12. The cylinder 11 is also provided with an ignition plug 14 that ignites hydrogen gas supplied to the combustion chamber 13.

[0011] The internal combustion engine 10 includes an intake passage 15 and an exhaust passage 16. The intake passage 15 is a flow path through which air flows to be supplied to the combustion chamber 13. When combustion gas containing hydrogen gas and air is combusted in the combustion chamber 13, exhaust gas is generated in the combustion chamber 13. The exhaust gas thus generated in the combustion chamber 13 is discharged to the exhaust passage 16.

[0012] <Gaseous fuel supply device> The gaseous fuel supply device 20 includes an in-cylinder injection valve 21, a storage tank 22, a supply passage 23, a pressure reducing valve 24, a shutoff valve 25, and a control device 50. The in-cylinder injection valve 21 injects hydrogen gas into the combustion chamber 13 in the cylinder 11. One in-cylinder injection valve 21 is provided for each cylinder 11. The configuration of the in-cylinder injection valve 21 will be described later.

[0013] The storage tank 22 stores high-pressure hydrogen gas. Supply flow path 23 guides hydrogen gas in storage tank 22 to in-cylinder injection valve 21. That is, when hydrogen gas flows out from storage tank 22 to supply flow path 23, the hydrogen gas flows in supply flow path 23 toward in-cylinder injection valve 21.

[0014] The pressure reducing valve 24 is provided in the supply flow path 23. The pressure reducing valve 24 is a mechanical valve that reduces the pressure of the high-pressure hydrogen gas that has flowed out from the storage tank 22 into the supply flow path 23. The shutoff valve 25 is provided in the supply flow path 23. More specifically, the shutoff valve 25 is disposed in a portion of the supply flow path 23 downstream of the pressure reducing valve 24. The shutoff valve 25 is configured to be switchable between an open state and a closed state. The open state is a state of the shutoff valve 25 that allows the supply of gaseous fuel to the in-cylinder injection valve 21. The closed state is a state of the shutoff valve 25 that stops the supply of gaseous fuel to the in-cylinder injection valve 21. When the shutoff valve 25 is in the open state, hydrogen gas in the storage tank 22 is supplied to the in-cylinder injection valve 21 through the supply flow path 23. On the other hand, when the shutoff valve 25 is in the closed state, hydrogen gas in the storage tank 22 is not supplied to the in-cylinder injection valve 21. However, hydrogen gas accumulated in the portion of the supply flow path 23 downstream of the shutoff valve 25 can be supplied to the in-cylinder injection valve 21, allowing the internal combustion engine 10 to continue operating.

[0015] The shutoff valve 25 is an electronically controlled solenoid valve that operates based on instructions from the control device 50. <In-cylinder injection valve> The direct injection valve 21 will be described with reference to FIG. 2. The direct injection valve 21 includes a needle 31, an electromagnetic solenoid 32, a nozzle 33, and a needle spring 34. Hydrogen gas is supplied to the interior of the direct injection valve 21 via a supply passage 23. The nozzle 33 is a hydrogen gas outlet that connects the inside and outside of the direct injection valve 21. The direct injection valve 21 is assembled to the internal combustion engine 10 with the nozzle 33 exposed to the combustion chamber 13. The needle 31 is a valve body that opens and closes the nozzle 33. A protective film such as a DLC film is formed on the surface of the needle 31 to increase the rigidity of the needle 31. "DLC" stands for "diamond-like carbon." When energized, the electromagnetic solenoid 32 generates an electromagnetic attractive force that drives the needle 31 in the direction that opens the nozzle 33. The needle spring 34 biases the needle 31 toward the side that closes the nozzle hole 33. Therefore, when the electromagnetic solenoid 32 is energized, the needle 31 moves away from the nozzle hole 33, causing the hydrogen gas in the in-cylinder injection valve 21 to flow out from the nozzle hole 33.

[0016] It should be noted that the part of the direct injection valve 21 that is exposed to the combustion chamber 13 is referred to as "tip portion 21A of the direct injection valve 21" (see FIG. 1). <Control device> As shown in FIG. 1, detection signals are input to the control device 50 from multiple sensors. The multiple sensors include an air flow meter 41 and a fuel pressure sensor 42. The air flow meter 41 detects the flow rate of air flowing through the intake passage 15. The fuel pressure sensor 42 detects the fuel pressure of hydrogen gas supplied to the direct injection valve 21. Specifically, the fuel pressure sensor 42 detects the fuel pressure in a portion of the supply flow path 23 downstream of the shutoff valve 25. The air flow rate based on the detection signal from the air flow meter 41 is referred to as the "intake air amount GA." The fuel pressure based on the detection signal from the fuel pressure sensor 42 is referred to as the "supply fuel pressure Pinj."

[0017] The control device 50 includes a processing circuit 51. For example, the processing circuit 51 is an electronic control device. In this case, the processing circuit 51 includes a CPU 52 and a memory 53. The memory 53 stores a control program executed by the CPU 52. The CPU 52 executes the control program, causing the processing circuit 51 to control the in-cylinder injection valve 21 and the shutoff valve 25.

[0018] <Shut-off valve control> 3, a processing routine will be described showing the flow of processing executed by the processing circuit 51 to control the shutoff valve 25. While the internal combustion engine 10 is operating, the processing circuit 51 repeatedly executes this processing routine.

[0019] In step S11, the processing circuit 51 acquires the injector temperature TPinj, which is the temperature of the tip 21A of the in-cylinder injection valve 21. For example, the processing circuit 51 acquires, as the injector temperature TPinj, an estimated value of the temperature based on the temperature of the combustion chamber 13 and the length of the opening period of the in-cylinder injection valve 21. In this case, the processing circuit 51 acquires, as the injector temperature TPinj, a higher value as the temperature of the combustion chamber 13 is higher. The processing circuit 51 acquires, as the injector temperature TPinj, a higher value as the opening period of the in-cylinder injection valve 21 is shorter.

[0020] In step S13, the processing circuit 51 determines whether the injector temperature TPinj acquired in step S11 is higher than the temperature judgment value TPinjTh. If the temperature of the tip portion 21A of the in-cylinder injection valve 21 becomes too high, the film formed on the surface of the needle 31 becomes more susceptible to wear. Therefore, if the temperature of the tip portion 21A remains too high, the life of the in-cylinder injection valve 21 is likely to be shortened. Therefore, the temperature judgment value TPinjTh is set as a criterion for determining whether the temperature of the tip portion 21A is too high. If the injector temperature TPinj is equal to or lower than the temperature judgment value TPinjTh, it is determined that protection of the in-cylinder injection valve 21 is not yet necessary. If the injector temperature TPinj is higher than the temperature judgment value TPinjTh, it is determined that protection of the in-cylinder injection valve 21 is necessary. Therefore, if the injector temperature TPinj is equal to or lower than the temperature judgment value TPinjTh (S13: NO), the processing circuit 51 proceeds to step S15.

[0021] In step S15, the processing circuit 51 determines whether the shutoff valve 25 is in a closed state. If the shutoff valve 25 is in a closed state (S15: YES), the processing circuit 51 proceeds to step S17. On the other hand, if the shutoff valve 25 is not in a closed state (S15: NO), the processing circuit 51 temporarily ends this processing routine because the shutoff valve 25 is in an open state.

[0022] In step S17, the processing circuit 51 opens the shutoff valve 25. After that, the processing circuit 51 temporarily ends this processing routine. On the other hand, in step S13, if the injection valve temperature TPinj is higher than the temperature determination value TPinjTh (S13: YES), the processing circuit 51 starts the opening / closing process including steps S21 to S31. The opening / closing process is a process of repeatedly closing the shutoff valve 25 and opening the shutoff valve 25.

[0023] Specifically, in step S21, the processing circuit 51 closes the shutoff valve 25. In this way, even when the shutoff valve 25 is closed, the fuel injection from the direct injection valve 21 continues. Therefore, the pressure of the fuel supplied to the direct injection valve 21 gradually decreases. After closing the shutoff valve 25, the processing circuit 51 transitions to step S23.

[0024] In step S23, the processing circuit 51 calculates the integrated valve closing time value TMc. That is, the processing circuit 51 calculates the integrated value of the time during which the shutoff valve 25 is in the closed state during one execution of the opening / closing process as the integrated valve closing time value TMc. When the opening / closing process ends, the processing circuit 51 resets the integrated valve closing time value TMc to 0 (zero).

[0025] In the next step S25, the processing circuit 51 determines whether the valve closing time integrated value TMc calculated in step S23 is equal to or greater than a predetermined determination time TMcTh. The determination time TMcTh is set as a criterion for determining whether the temperature of the tip portion 21A of the direct injection valve 21 has decreased due to the execution of the opening / closing process. If the valve closing time integrated value TMc is equal to or greater than the determination time TMcTh, it is determined that the temperature of the tip portion 21A may have decreased sufficiently. If the valve closing time integrated value TMc is less than the determination time TMcTh, it is determined that the temperature of the tip portion 21A has not decreased sufficiently. Therefore, if the valve closing time integrated value TMc is equal to or greater than the determination time TMcTh (S25: YES), the processing circuit 51 returns the process to step S11. That is, the processing circuit 51 ends the opening / closing process. On the other hand, if the valve closing time integrated value TMc is less than the determination time TMcTh (S25: NO), the processing circuit 51 proceeds to step S27. That is, the processing circuit 51 continues the opening and closing process.

[0026] In step S27, the processing circuit 51 determines whether the supply fuel pressure Pinj is equal to or less than the pressure lower limit PinjL. The amount of fuel injected by the in-cylinder injection valve 21 is determined by the pressure of the fuel supplied to the in-cylinder injection valve 21 and the length of time the in-cylinder injection valve 21 is energized. Therefore, if the pressure of the fuel supplied to the in-cylinder injection valve 21 is too low, an appropriate amount of hydrogen gas cannot be supplied to the combustion chamber 13 by a single fuel injection by the in-cylinder injection valve 21. Therefore, the pressure lower limit PinjL is set as a criterion for determining whether an appropriate amount of hydrogen gas can be supplied to the combustion chamber 13 by a single fuel injection. If the supply fuel pressure Pinj is higher than the pressure lower limit PinjL, ​​it is determined that an appropriate amount of hydrogen gas can be supplied to the combustion chamber 13 by a single fuel injection. If the supply fuel pressure Pinj is equal to or less than the pressure lower limit PinjL, ​​it is determined that there is a possibility that an appropriate amount of hydrogen gas cannot be supplied to the combustion chamber 13 by a single fuel injection. Therefore, if the supply fuel pressure Pinj is higher than the pressure lower limit value PinjL (S27: NO), the processing circuit 51 returns the processing to step S23. In this case, the processing circuit 51 keeps the shutoff valve 25 closed. On the other hand, if the supply fuel pressure Pinj is equal to or lower than the pressure lower limit value PinjL (S27: YES), the processing circuit 51 shifts the processing to step S29.

[0027] In step S29, the processing circuit 51 opens the shutoff valve 25. Then, the processing circuit 51 shifts the processing to step S31. In step S31, the processing circuit 51 determines whether the supply fuel pressure Pinj has become higher than the pressure determination value PinjTh. A pressure equal to or higher than the pressure lower limit value PinjL is set as the pressure determination value PinjTh. That is, the pressure determination value PinjTh may be equal to or higher than the pressure lower limit value PinjL. When the supply fuel pressure Pinj is higher than the pressure determination value PinjTh, it is determined that an appropriate amount of hydrogen gas can be supplied to the combustion chamber 13 with one fuel injection. Therefore, when the supply fuel pressure Pinj has become higher than the pressure determination value PinjTh (S31: YES), the processing circuit 51 returns the processing to step S21. In this case, the processing circuit 51 closes the shutoff valve 25. On the other hand, if the supply fuel pressure Pinj is equal to or less than the pressure determination value PinjTh (S31: NO), the processing circuit 51 repeats the determination of step S31 until the supply fuel pressure Pinj becomes higher than the pressure determination value PinjTh. In this case, the processing circuit 51 maintains the shutoff valve 25 in the open state.

[0028] <Direct injection valve control> 4, a processing routine will be described showing the flow of processing executed by the processing circuit 51 to determine the energization time TMinj of the direct injection valve 21. While the internal combustion engine 10 is operating, the processing circuit 51 repeatedly executes this processing routine.

[0029] In step S41, the processing circuit 51 acquires a required injection amount QinjRq, which is a required value of the fuel injection amount of the direct injection valve 21. For example, the processing circuit 51 acquires a fuel injection amount according to the target value of the air-fuel ratio and the intake air amount GA as the required injection amount QinjRq.

[0030] In the next step S43, the processing circuit 51 acquires the supplied fuel pressure Pinj. Then, in step S45, the processing circuit 51 determines the energization time TMinj for the direct injection valve 21, which corresponds to the length of the opening period of the direct injection valve 21, based on the required injection amount QinjRq and the supply fuel pressure Pinj. That is, the processing circuit 51 determines a longer energization time TMinj as the required injection amount QinjRq increases. The processing circuit 51 determines a longer energization time TMinj as the supply fuel pressure Pinj decreases. Thereafter, the processing circuit 51 temporarily ends this processing routine.

[0031] <Actions and Effects of the First Embodiment> When the internal combustion engine 10 is operating, combustion gas is burned in the combustion chamber 13. Therefore, the tip portion 21A of the in-cylinder injection valve 21 is exposed to high-temperature combustion gas. As a result, the temperature of the tip portion 21A increases. When the injection valve temperature TPinj becomes higher than the temperature determination value TPinjTh, the processing circuit 51 starts the opening / closing process.

[0032] As a result, shutoff valve 25 of gaseous fuel supply device 20 is closed, and hydrogen gas from storage tank 22 is no longer supplied to in-cylinder injection valve 21. Even in this state, fuel injection from in-cylinder injection valve 21 continues, and the pressure of the fuel supplied from supply passage 23 to in-cylinder injection valve 21 gradually decreases.

[0033] When the pressure of the fuel supplied from the supply passage 23 to the in-cylinder injection valve 21 decreases, the energization time TMinj to the in-cylinder injection valve 21 increases even if the required injection amount QinjRq is constant. This increases the time during which relatively low-temperature hydrogen gas flows through the in-cylinder injection valve 21. As a result, the temperature of the tip portion 21A of the in-cylinder injection valve 21 tends to decrease.

[0034] When the supply fuel pressure Pinj falls below the lower limit pressure PinjL because the shutoff valve 25 is closed, the shutoff valve 25 opens. This causes hydrogen gas in the storage tank 22 to be supplied to the in-cylinder injection valve 21 via the supply passage 23. As a result, the pressure of the fuel supplied from the supply passage 23 to the in-cylinder injection valve 21 increases, maintaining a state in which an appropriate amount of hydrogen gas can be supplied from the in-cylinder injection valve 21 to the combustion chamber 13.

[0035] Therefore, the gaseous fuel supply device 20 can prevent the temperature of the tip portion 21A of the direct injection valve 21 from increasing while properly operating the internal combustion engine 10. In other words, the gaseous fuel supply device 20 can prevent the life of the direct injection valve 21 from being shortened.

[0036] In this embodiment, the following effects can be further obtained. (1) When the current supply time TMinj is lengthened by closing the shutoff valve 25, the temperature of the tip portion 21A of the direct injection valve 21 decreases. Therefore, when the valve closing time integrated value TMc, which is the integrated value of the time during which the shutoff valve 25 is in the closed state as a result of the opening and closing process, reaches the judgment time TMcTh, the processing circuit 51 terminates the opening and closing process. In this way, the processing circuit 51 executes the opening and closing process until the valve closing time integrated value TMc becomes equal to or greater than the judgment time TMcTh, thereby decreasing the temperature of the tip portion 21A. As a result, the gaseous fuel supply device 20 can prevent the life of the direct injection valve 21 from being shortened.

[0037] (2) However, even if the valve closing time integrated value TMc becomes equal to or greater than the judgment time TMcTh, the injector temperature TPinj may not become equal to or less than the temperature judgment value TPinjTh. In this case, in the gaseous fuel supply device 20, the processing circuit 51 executes the opening / closing process again. As a result, the gaseous fuel supply device 20 can sufficiently lower the temperature of the tip portion 21A of the direct injection valve 21.

[0038] (3) Furthermore, while the opening and closing process is being performed, the pressure of the fuel supplied from the supply passage 23 to the in-cylinder injection valve 21 is reduced. Therefore, while the opening and closing process is being performed, the injection pressure of the hydrogen gas from the in-cylinder injection valve 21 is reduced. When the injection pressure is reduced in this manner, the pressure applied to the needle 31 when the in-cylinder injection valve 21 is closed is reduced. As a result, the impact load applied to the needle 31 when the needle 31 closes the nozzle hole 33 is reduced. This makes it difficult for the film formed on the surface of the needle 31 to wear.

[0039] (Second embodiment) A second embodiment of the gaseous fuel supply device will be described with reference to Fig. 5. In the second embodiment, some of the opening and closing processes are different from those in the first embodiment. In the following description, differences from the first embodiment will be mainly described, and the same components as those in the first embodiment will be assigned the same reference numerals, and redundant description will be omitted.

[0040] <Shut-off valve control> 5, a processing routine will be described showing the flow of processing executed by the processing circuit 51 to control the shutoff valve 25. While the internal combustion engine 10 is operating, the processing circuit 51 repeatedly executes this processing routine.

[0041] In step S11, the processing circuit 51 acquires the injector temperature TPinj, which is the temperature of the tip portion 21A of the in-cylinder injection valve 21. In the next step S13, the processing circuit 51 determines whether the injector temperature TPinj is higher than the temperature determination value TPinjTh. If the injector temperature TPinj is equal to or lower than the temperature determination value TPinjTh (S13: NO), the processing circuit 51 executes the processes of steps S15 and S17 and temporarily ends this processing routine. On the other hand, if the injector temperature TPinj is higher than the temperature determination value TPinjTh (S13: YES), the processing circuit 51 starts the opening / closing process.

[0042] Specifically, in step S21, the processing circuit 51 closes the shutoff valve 25. Subsequently, in step S211, the processing circuit 51 acquires the injector temperature TPinj, similar to step S11. Then, in step S213, the processing circuit 51 determines whether the injector temperature TPinj is higher than the temperature determination value TPinjTh, similar to step S13. If the injector temperature TPinj is higher than the temperature determination value TPinjTh (S213: YES), the processing circuit 51 shifts the processing to step S27. The processing flow from step S27 onwards is the same as in the first embodiment, and therefore will not be described again.

[0043] On the other hand, in step S213, if the injector temperature TPinj is equal to or lower than the temperature determination value TPinjTh (S213: NO), the processing circuit 51 proceeds to step S15. That is, when the injector temperature TPinj becomes equal to or lower than the temperature determination value TPinjTh by the execution of the opening / closing process, the processing circuit 51 ends the opening / closing process.

[0044] <Effects of the second embodiment> In this embodiment, similarly to the first embodiment, it is possible to appropriately operate the internal combustion engine 10 while suppressing an increase in the temperature of the tip portion 21A of the direct injection valve 21. In other words, the gaseous fuel supply device 20 can suppress a shortening of the life of the direct injection valve 21.

[0045] Furthermore, the processing circuit 51 continues the opening / closing process until the injector temperature TPinj becomes equal to or less than the temperature determination value TPinjTh. This allows the gaseous fuel supply device 20 to sufficiently lower the temperature of the tip end portion 21A as the opening / closing process is performed. Also, when the injector temperature TPinj becomes equal to or less than the temperature determination value TPinjTh, the opening / closing process is terminated, thereby preventing the execution time of the opening / closing process from becoming excessively long.

[0046] (Example of change) The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0047] In the first embodiment, the processing circuit 51 may terminate the opening / closing process when the injector temperature TPinj becomes equal to or lower than the temperature judgment value TPinjTh even if the valve closing time integrated value TMc is less than the judgment time TMcTh.

[0048] During the opening / closing process, when the duration that the shutoff valve 25 remains open reaches a specified time, the processing circuit 51 may determine that the pressure of the gaseous fuel supplied to the in-cylinder injection valve 21 has become equal to or lower than the lower pressure limit value, and may close the shutoff valve 25.

[0049] When a fuel injection valve with a built-in temperature sensor that detects the temperature of the tip is used as the in-cylinder injection valve, the processing circuit 51 may obtain the detection value of the temperature sensor as the injection valve temperature TPinj.

[0050] The gaseous fuel supply device may be a device that supplies a gaseous fuel other than hydrogen gas to the internal combustion engine. Examples of the other gaseous fuel include compressed natural gas. The processing circuit 51 is not limited to a circuit having a CPU and ROM and executing software processing. In other words, the processing circuit 51 may have any one of the following configurations (a), (b), and (c):

[0051] (a) The processing circuit 51 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0052] (b) The processing circuit 51 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits (ASICs) or FPGAs. ASIC stands for "Application Specific Integrated Circuit," and FPGA stands for "Field Programmable Gate Array."

[0053] (c) The processing circuitry 51 includes a processor that executes some of the various processes in accordance with a computer program, and dedicated hardware circuits that execute the remaining processes of the various processes. [Explanation of symbols]

[0054] 10...internal combustion engine, 11...cylinder, 20...gaseous fuel supply device, 21...in-cylinder injection valve, 21A...tip portion, 22...storage tank, 23...supply flow path, 24...pressure reducing valve, 25...shutoff valve, 50...control device, 51...processing circuit

Claims

[Claim 1] A gaseous fuel supply device applied to an internal combustion engine having a cylinder, an in-cylinder injection valve that injects gaseous fuel into the cylinder; a storage tank for storing gaseous fuel; a supply flow path that guides the gaseous fuel in the storage tank to the direct injection valve; a pressure reducing valve provided in the supply passage and configured to reduce the pressure of the gaseous fuel flowing from the storage tank into the supply passage; a shutoff valve that is arranged in a portion of the supply flow path downstream of the pressure reducing valve and is configured to be switchable between an open state that allows the supply of gaseous fuel to the in-cylinder injection valve and a closed state that stops the supply of gaseous fuel to the in-cylinder injection valve; a processing circuit that controls the in-cylinder injection valve and the shutoff valve, The processing circuitry determining a power supply time for the in-cylinder injection valve based on a pressure of the gaseous fuel supplied from the supply passage to the in-cylinder injection valve and a required value of an injection amount of the gaseous fuel of the in-cylinder injection valve; when the temperature of the direct injection valve becomes higher than a temperature determination value during operation of the internal combustion engine, an opening / closing process is started in which the shutoff valve is repeatedly brought into the closed state and the open state; When an integrated value of the time during which the shutoff valve is in the closed state due to the execution of the opening / closing process reaches a predetermined judgment time, the opening / closing process is terminated, The opening / closing process is a process of closing the shutoff valve when the pressure of the gaseous fuel supplied from the supply flow path to the in-cylinder injection valve is higher than a pressure lower limit value, and opening the shutoff valve when the pressure of the gaseous fuel supplied to the in-cylinder injection valve becomes equal to or lower than the pressure lower limit value. Gaseous fuel supply system.

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