JP7370356B2 - engine system - Google Patents

Description

The present invention relates to an engine system.

Patent Document 1 discloses a direct injection engine that uses natural gas as fuel. In engines that use gas as fuel, a fuel injection valve is used to inject high-pressure gas into a cylinder, so the fuel supply pipe from the gas tank to the fuel injection valve is sealed at high pressure. When the engine is stopped, high-pressure gas is maintained in the fuel supply pipe. In this case, there is a risk of gas leaking from the fuel injection valve through each cylinder, so the pressure of the gas in the fuel supply pipe is lowered. Specifically, when the engine is stopped, gas in the fuel supply pipe is released to the outside to lower the pressure.

JP2020-56380A

However, the engine described in Patent Document 1 is merely intended to lower the pressure of gas in the fuel supply pipe in order to prevent gas leakage. Further, Patent Document 1 does not disclose a specific method for releasing gas in the fuel supply pipe to the outside when the engine is stopped.

An object of the present invention is to provide an engine system that can effectively discharge gaseous fuel remaining in a gaseous fuel supply pipe that supplies gaseous fuel to an engine.

According to one aspect of the present invention, an engine system includes an engine, a gaseous fuel supply pipe, a fuel flow rate adjustment section, and a fuel discharge section. The engine generates power by burning at least gaseous fuel. A gaseous fuel supply pipe supplies the gaseous fuel to the engine. The fuel flow rate adjustment section can cut off the supply of the gaseous fuel to the gaseous fuel supply pipe. The fuel discharge unit is configured to remove the gaseous fuel remaining in the gaseous fuel supply pipe from the gaseous fuel supply pipe using gas at a pressure higher than atmospheric pressure when the fuel flow rate adjustment unit has cut off the supply of the gaseous fuel. Discharge outside.

According to the present invention, it is possible to provide an engine system that can effectively discharge gaseous fuel remaining in a gaseous fuel supply pipe that supplies gaseous fuel to an engine.

1 is a diagram showing the configuration of an engine system according to an embodiment of the present invention. It is a sectional view showing a hydrogen fuel supply part concerning this embodiment. FIG. 1 is a block diagram showing an engine system according to the present embodiment. 5 is a time chart showing changes in various states of the engine system when stopping the engine according to the present embodiment. 2 is a flowchart showing a method for discharging residual hydrogen when stopping an engine according to the present embodiment. 5 is a time chart showing changes in various states of the engine system when the operating mode of the engine according to the present embodiment is shifted to a liquid fuel mode. It is a flowchart which shows the residual hydrogen discharge method when shifting the operation mode of the engine based on this embodiment to liquid fuel mode.

Embodiments of the present invention will be described below with reference to the drawings. In addition, in the drawings, the same or corresponding parts are given the same reference numerals and the description will not be repeated.

First, with reference to FIG. 1, an engine system 100 according to an embodiment of the present invention will be described. Engine system 100 shown in FIG. 1 generates power by burning at least gaseous fuel. The gaseous fuel is, but is not particularly limited to, for example, hydrogen, ammonia, or natural gas. The natural gas is, for example, vaporized liquefied natural gas (LNG). Engine system 100 is, for example, mounted on a vehicle, installed inside a building, or installed outdoors. The vehicle is, for example, a ship, a car, a railway vehicle, or an airplane.

Hereinafter, in this specification, hydrogen fuel will be described as an example of the gaseous fuel. Further, a ship 200 will be described as an example of a vehicle on which the engine system 100 is mounted. In addition, in this specification, the ship 200 can be read as a "vehicle", the hydrogen fuel can be read as a "gaseous fuel", and the hydrogen can be read as a "fuel gas" or a "fuel".

As shown in FIG. 1, a ship 200 includes an engine system 100. Engine system 100 generates power by burning at least hydrogen fuel.

The engine system 100 includes an engine 1, a liquefied hydrogen tank 3, a vaporizer 5, a hydrogen fuel adjustment section 7, a pressure detection section 9, a hydrogen fuel supply pipe 10, a supercharger 11, an intercooler 13, It includes an air supply pipe 15, an intake manifold 17, and an exhaust pipe 19. The intake manifold 17 can also be written as the "air supply manifold 17."

The engine 1 generates power by burning at least hydrogen fuel. In this embodiment, the engine 1 has a hydrogen fuel mode and a liquid fuel mode. The hydrogen fuel mode is a mode in which the engine 1 generates power by burning hydrogen fuel. The hydrogen fuel mode is, for example, a hydrogen combustion mode in which the engine 1 functions as a hydrogen engine. The liquid fuel mode is a mode in which the engine 1 generates power by burning liquid fuel. The liquid fuel is, for example, light oil or heavy oil. The liquid fuel mode is, for example, a diesel mode in which the engine 1 functions as a diesel engine.

The hydrogen fuel mode corresponds to an example of the "gaseous fuel mode" of the present invention. The "gaseous fuel mode" is a mode in which the engine 1 generates power by burning gaseous fuel.

The hydrogen fuel supply pipe 10 supplies gaseous hydrogen fuel to the engine 1 . Specifically, the liquefied hydrogen tank 3, the vaporizer 5, the hydrogen fuel adjustment section 7, and the pressure detection section 9 are arranged in this order from upstream to downstream.

In this embodiment, unless otherwise specified, "upstream" indicates the upstream side of the flow of hydrogen fuel when hydrogen fuel is supplied into the engine 1. Moreover, "downstream" indicates the downstream of the flow of hydrogen fuel when supplying the hydrogen fuel into the interior of the engine 1.

The liquefied hydrogen tank 3 stores liquid hydrogen fuel that is hydrogen fuel in a liquid state. The liquefied hydrogen tank 3 is a supply source of hydrogen fuel. The vaporizer 5 vaporizes the liquid hydrogen fuel supplied from the liquefied hydrogen tank 3 and supplies gaseous hydrogen fuel to the hydrogen fuel supply pipe 10 . Note that hydrogen fuel may be stored and stored as compressed high-pressure gas. In this case, for example, the engine system 100 includes a compressed hydrogen tank that stores hydrogen fuel as compressed high-pressure gas instead of the liquefied hydrogen tank 3, and does not include the vaporizer 5.

The hydrogen fuel adjustment section 7 adjusts the hydrogen fuel within the hydrogen fuel supply pipe 10. The hydrogen fuel adjustment section 7 is, for example, a gas valve unit (GVU). The gas valve unit includes, for example, multiple valves, multiple piping, one or more gas filters, and one or more gas regulators.

Specifically, the hydrogen fuel adjustment section 7 includes a fuel flow rate adjustment section 71, a fuel discharge section 72, and a discharge pipe 73. The fuel flow rate adjustment section 71 is arranged in the hydrogen fuel supply pipe 10. The discharge pipe 73 branches from the hydrogen fuel supply pipe 10 downstream of the fuel flow rate adjustment section 71 . The fuel discharge part 72 is arranged in the discharge pipe 73.

The fuel flow rate adjustment section 71 adjusts the flow rate of hydrogen fuel flowing through the hydrogen fuel supply pipe 10 . Adjustment of the flow rate of hydrogen fuel by the fuel flow rate adjustment section 71 includes not only increasing and decreasing the flow rate continuously or stepwise, but also setting the flow rate to zero. It is sufficient that the fuel flow rate adjustment section 71 can at least switch the flow path of the hydrogen fuel supply pipe 10 between an open state and a closed state. The fuel flow rate adjustment section 71 is, for example, a flow rate adjustment valve or an on-off valve. The flow rate regulating valve is, for example, a pressure regulating valve. The pressure regulating valve is composed of, for example, a single valve or a plurality of valves.

The fuel flow rate adjustment unit 71 can block the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X of the hydrogen fuel supply pipes 10 by blocking the flow path of the hydrogen fuel supply pipe 10. The hydrogen fuel supply pipe 10X indicates a pipe of the hydrogen fuel supply pipe 10 that extends from the fuel flow rate adjustment section 71 to the hydrogen fuel supply section 55. Therefore, the fuel flow rate adjustment section 71 can cut off the supply of hydrogen fuel to the hydrogen fuel supply section 55. In the example of FIG. 1, the fuel flow rate adjustment section 71 is connected to the upstream end of the hydrogen fuel supply pipe 10X, and the hydrogen fuel supply section 55 is connected to the downstream end of the hydrogen fuel supply pipe 10X. Further, the discharge pipe 73 branches from the hydrogen fuel supply pipe 10X downstream of the fuel flow rate adjustment section 71.

The hydrogen fuel supply pipe 10X corresponds to an example of the "gaseous fuel supply pipe" of the present invention.

The fuel discharge unit 72 drains the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X with gas at a pressure higher than atmospheric pressure when the fuel flow rate adjustment unit 71 has cut off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X. It is discharged to the outside of the hydrogen fuel supply pipe 10X. Therefore, according to this embodiment, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X that supplies hydrogen fuel to the engine 1 can be effectively discharged. For example, most or all of the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X can be discharged to the outside of the hydrogen fuel supply pipe 10X.

Specifically, by opening the flow path of the discharge pipe 73, the fuel discharge part 72 discharges gas at a pressure higher than atmospheric pressure in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. , the hydrogen fuel remaining in the hydrogen fuel supply pipe 10 is discharged via the discharge pipe 73. For example, the fuel discharge section 72 discharges the hydrogen fuel remaining in the hydrogen fuel supply pipe 10 through the discharge pipe 73 into a room where the engine 1 is installed (hereinafter referred to as "engine room"). Hydrogen fuel discharged into the engine room is diluted by air. Therefore, in the engine compartment, the concentration of hydrogen fuel decreases to a value outside the flammable range of hydrogen. That is, in the engine room, the concentration of hydrogen fuel decreases to less than 4%. Therefore, hydrogen fuel will not ignite in the engine room. The fuel discharge part 72 is, for example, a throttle valve. A throttle valve is composed of one or more valves.

Preferably, the fuel discharge unit 72 releases the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X from atmospheric pressure by opening the hydrogen fuel supply pipe 10X after the fuel flow rate adjustment unit 71 cuts off the supply of hydrogen fuel. The gas under high pressure is also discharged to the outside of the hydrogen fuel supply pipe 10X. According to this preferred example, after the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off, but before the hydrogen fuel supply pipe 10X is opened and hydrogen fuel is discharged, the hydrogen fuel is supplied from the hydrogen fuel supply pipe 10X. Hydrogen fuel can be supplied to the engine 1. Therefore, hydrogen fuel can be burned in the engine 1 without waste. Furthermore, by consuming the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X without waste, the amount of hydrogen fuel remaining in the hydrogen fuel supply pipe 10X can be reduced.

Details of the control when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X will be described later. Hereinafter, in this embodiment, as an example, the gas having a pressure higher than atmospheric pressure is air having a pressure higher than atmospheric pressure. Note that the gas having a pressure higher than atmospheric pressure may be, for example, an inert gas. Inert gases are, for example, nitrogen, argon, helium or carbon dioxide.

The pressure detection unit 9 detects the pressure of gas present in the hydrogen fuel supply pipe 10. The pressure detection unit 9 is, for example, a pressure sensor.

The air supply pipe 15 supplies air outside the engine 1 to the engine 1 via the supercharger 11 , intercooler 13 , and intake manifold 17 . Specifically, the supercharger 11 and the intercooler 13 are arranged in this order from upstream to downstream of the air supply. The supercharger 11 supplies air at a pressure higher than atmospheric pressure to the inside of the engine 1. Specifically, the supercharger 11 compresses the air flowing through the air supply pipe 15 and causes air at a pressure higher than atmospheric pressure to flow through the air supply pipe 15. Hereinafter, "compressed air" refers to air at a pressure greater than atmospheric pressure.

The intercooler 13 cools the air compressed by the supercharger 11 and supplies it to the intake manifold 17 . The intake manifold 17 supplies compressed and cooled air to the engine 1 . Specifically, the engine 1 has a plurality of cylinders 1a. In FIG. 1, one cylinder 1a is illustrated for the sake of simplification of the drawing. The intake manifold 17 supplies compressed and cooled air to each cylinder 1a. Note that the engine 1 may have one cylinder 1a. In this case, the intake manifold 17 can be omitted.

Exhaust gas discharged from the engine 1 flows through the exhaust pipe 19 . That is, the exhaust pipe 19 discharges exhaust gas to the outside of the engine 1. The exhaust gas is utilized by the supercharger 11. Specifically, supercharger 11 includes a turbine 111 and a compressor 112. The turbine 111 is arranged in the exhaust pipe 19 and the compressor 112 is arranged in the air supply pipe 15. The turbine 111 is rotated by exhaust gas flowing through the exhaust pipe 19 and transmits rotational force to the compressor 112. The compressor 112 is driven by the rotational force of the turbine 111, compresses the air flowing through the air supply pipe 15, and generates air at a pressure higher than atmospheric pressure.

The engine 1 includes a cylinder head 51, a cylinder block 52, an intake valve 53, an exhaust valve 54, a hydrogen fuel supply section 55, a liquid fuel supply section 56, an ignition induction section 57, a piston 58, a connecting rod 59, a crankshaft 60, and It includes an engine rotation speed detection section 62. The intake valve 53 can also be described as an "air supply valve 53." Further, the engine 1 has a combustion chamber 61. Combustion chamber 61 is formed in cylinder block 52 . Combustion chamber 61 is a space between cylinder head 51 and piston 58.

Cylinder head 51 is fixed to the top of cylinder block 52. The cylinder head 51 has an intake passage 63 and an exhaust passage 64. The intake passage 63 can also be described as an "air supply passage 63."

The intake manifold 17 is connected to the entrance of the intake passage 63. Therefore, compressed and cooled air is supplied to the intake passage 63 from the intake manifold 17. An outlet of the intake passage 63 is connected to the combustion chamber 61.

Hydrogen fuel supply section 55 is arranged in cylinder head 51 . When the hydrogen fuel is burned in the combustion chamber 61, that is, in the hydrogen fuel mode, the hydrogen fuel supply unit 55 supplies hydrogen fuel supplied from the hydrogen fuel supply pipe 10X to the inside of the engine 1. In the example of FIG. 1, the hydrogen fuel supply section 55 supplies hydrogen fuel from the hydrogen fuel supply pipe 10X to the intake passage 63 in the hydrogen fuel mode, as indicated by the arrow SL. In this case, for example, the hydrogen fuel supply section 55 injects hydrogen fuel. Therefore, hydrogen fuel is mixed with air supplied from the intake manifold 17 and supplied to the combustion chamber 61. The hydrogen fuel supplied by the hydrogen fuel supply unit 55 is gaseous fuel that is burned to drive the engine 1 (specifically, the piston 58).

Note that, for example, the hydrogen fuel supply section 55 may be arranged in the intake manifold 17 or may be arranged in the air supply pipe 15 downstream of the intercooler 13.

The hydrogen fuel supply section 55 corresponds to an example of the "gaseous fuel supply section" of the present invention. The hydrogen fuel supply section 55 includes, for example, a gas admission valve (GAV) or a gas injector.

Specifically, the intake valve 53 is arranged at the outlet of the intake passage 63. The intake valve 53 opens or closes the outlet of the intake passage 63. When the intake valve 53 opens the outlet of the intake passage 63, hydrogen fuel mixed with air is supplied to the combustion chamber 61. Specifically, when hydrogen fuel is combusted in the combustion chamber 61, that is, in the hydrogen fuel mode, when the intake valve 53 is opened, the hydrogen fuel supply unit 55 opens the hydrogen fuel flow path, so that the hydrogen fuel Hydrogen fuel is supplied into the engine 1 from the supply pipe 10X.

More specifically, when hydrogen fuel is burned in the combustion chamber 61, that is, in the hydrogen fuel mode, the hydrogen fuel supply section 55 repeats opening and closing of the hydrogen fuel flow path in synchronization with the opening and closing of the intake valve 53. , hydrogen fuel is intermittently supplied to the inside of the engine 1. In other words, in the hydrogen fuel mode, the hydrogen fuel supply unit 55 intermittently supplies hydrogen fuel to the inside of the engine 1 by alternately repeating supply and stop of supply of hydrogen fuel. In other words, in the hydrogen fuel mode, the hydrogen fuel supply section 55 supplies hydrogen to the interior of the engine 1 by alternately repeating a communication state and a cutoff state between the hydrogen fuel supply pipe 10X and the interior of the engine 1. Supply fuel intermittently. The communication state indicates a state in which the hydrogen fuel supply pipe 10X and the inside of the engine 1 are in communication with each other, and gas can flow between the hydrogen fuel supply pipe 10X and the inside of the engine 1. The cutoff state indicates a state in which the hydrogen fuel supply pipe 10X and the inside of the engine 1 are cut off, and gas cannot flow between the hydrogen fuel supply pipe 10X and the inside of the engine 1.

In the example of FIG. 1, since hydrogen fuel is supplied to the intake passage 63, the hydrogen fuel supply section 55 directly supplies hydrogen fuel into the interior of the engine 1. However, the hydrogen fuel supply section 55 may indirectly supply hydrogen fuel into the engine 1. For example, the hydrogen fuel supply section 55 may be arranged in the intake manifold 17. In this case, the hydrogen fuel supply section 55 supplies hydrogen fuel to the inside of the engine 1 via the intake manifold 17 by supplying hydrogen fuel to an intake passage (not shown) in the intake manifold 17 . Alternatively, for example, the hydrogen fuel supply section 55 may be arranged in the air supply pipe 15 downstream of the intercooler 13. In this case, the hydrogen fuel supply unit 55 supplies hydrogen fuel to the inside of the engine 1 via the intake pipe 15 and the intake manifold 17 by supplying hydrogen fuel to the flow path (not shown) of the intake pipe 15. .

Further, in the example of FIG. 1 , the hydrogen fuel supply unit 55 indirectly supplies hydrogen fuel to the combustion chamber 61 via the intake passage 63 by supplying hydrogen fuel to the intake passage 63 . However, the hydrogen fuel supply unit 55 may directly supply hydrogen fuel to the combustion chamber 61. As long as the hydrogen fuel supply section 55 can directly or indirectly supply hydrogen fuel to the combustion chamber 61, the arrangement of the hydrogen fuel supply section 55 is not particularly limited.

Here, in the present embodiment, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the hydrogen fuel supply section 55 opens the flow path of the hydrogen fuel (that is, connects the hydrogen fuel supply pipe 10X to the engine). 1), as shown by the arrow DL, air at a pressure higher than atmospheric pressure is supplied to the hydrogen fuel supply pipe 10X with the fuel flow rate adjustment section 71 cutting off the supply of hydrogen fuel. Introduce. Then, in a state where the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel, the fuel discharge section 72 supplies hydrogen fuel remaining in the hydrogen fuel supply pipe 10X with the air introduced into the hydrogen fuel supply pipe 10X. Discharge to the outside of pipe 10X.

Therefore, the hydrogen fuel supply section 55 is commonly used when introducing air with a pressure higher than atmospheric pressure into the hydrogen fuel supply pipe 10X and when supplying hydrogen fuel into the interior of the engine 1. In other words, the route for introducing air at a pressure higher than atmospheric pressure into the hydrogen fuel supply pipe 10X and the route for supplying hydrogen fuel into the engine 1 are the same. Therefore, there is no need for a dedicated air introduction mechanism for introducing air at a pressure higher than atmospheric pressure into the hydrogen fuel supply pipe 10X. As a result, the manufacturing cost of the engine system 100 can be reduced while realizing a configuration that can effectively discharge the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X.

In particular, in this embodiment, the air introduced into the hydrogen fuel supply pipe 10X when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is the air supplied by the supercharger 11. That is, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the hydrogen fuel supply section 55 opens the hydrogen fuel flow path (that is, communicates the hydrogen fuel supply pipe 10X with the inside of the engine 1). ), the air supplied by the supercharger 11 is introduced into the hydrogen fuel supply pipe 10X, as shown by the arrow DL. Therefore, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is removed from the "air with a pressure higher than atmospheric pressure" supplied by the supercharger 11 when the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. ” is discharged from the discharge pipe 73. Therefore, it is not necessary to install a dedicated compressor for discharging hydrogen fuel remaining in the hydrogen fuel supply pipe 10X. As a result, the manufacturing cost of the engine system 100 can be further reduced while realizing a configuration that can effectively discharge the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X. Note that the details of the control when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10 will be described later.

Specifically, in this embodiment, when discharging hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the hydrogen fuel supply unit 55 controls the fuel flow rate adjustment unit 71 to control the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X. By continuing to repeat the operation of opening and closing the hydrogen fuel flow path even before the hydrogen fuel supply is shut off, when the fuel flow rate adjustment unit 71 has shut off the supply of hydrogen fuel, the air at a pressure higher than atmospheric pressure can be used as hydrogen fuel. It is intermittently introduced into the supply pipe 10X.

That is, when discharging hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the hydrogen fuel supply section 55 starts supplying hydrogen fuel from before the fuel flow rate adjustment section 71 shuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X. By continuing the operation of alternately repeating the communication state and the cutoff state between the pipe 10X and the inside of the engine 1, the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X. , air at a pressure higher than atmospheric pressure is intermittently introduced into the hydrogen fuel supply pipe 10X.

Therefore, according to the present embodiment, when the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X, the pressure higher than atmospheric pressure is of air can be introduced into the hydrogen fuel supply pipe 10X. In other words, the hydrogen fuel supply section 55 can be easily controlled.

Next, with reference to FIG. 2, the hydrogen fuel supply section 55 will be explained. FIG. 2 is a cross-sectional view showing the hydrogen fuel supply section 55. As shown in FIG. 2, the hydrogen fuel supply section 55 is connected to the downstream end of the hydrogen fuel supply pipe 10X.

Hydrogen fuel supply section 55 includes, for example, a valve 551 and a sleeve 554. FIG. 2 shows the valve 551 in an open state. Valve 551 is, for example, a gas admission valve (GAV). Sleeve 554 has a substantially cylindrical shape. For example, sleeve 554 is generally cylindrical.

For example, the valve 551 is located at the top of the cylinder head 51. The downstream end of the hydrogen fuel supply pipe 10X is connected to the upstream side of the valve 551. On the other hand, a sleeve 554 is connected to the downstream side of the valve 551. The sleeve 554 extends from the downstream side of the valve 551 toward the intake passage 63. The sleeve 554 passes through the cylinder head 51 and projects into the intake passage 63.

In the open state, the valve 551 establishes communication between the flow path 110 of the hydrogen fuel supply pipe 10X and the inside of the engine 1 (in the example of FIG. 2, the intake passage 63). On the other hand, when the valve 551 is closed, the flow path 110 of the hydrogen fuel supply pipe 10X and the inside of the engine 1 (in the example of FIG. 2, the intake passage 63) are cut off.

Specifically, when the valve 551 is open, the flow path 110 of the hydrogen fuel supply pipe 10X and the flow path 556 of the sleeve 554 communicate with each other via the flow path 555 of the valve 551. Therefore, when the valve 551 is opened, the hydrogen fuel in the hydrogen fuel supply pipe 10X is supplied from the sleeve 554 to the intake passage 63, as shown by arrow SL. That is, the sleeve 554 injects hydrogen fuel into the intake passage 63.

On the other hand, when the valve 551 is closed, the flow path 555 is blocked. Therefore, when the valve 551 is closed, the supply of hydrogen fuel from the hydrogen fuel supply pipe 10 to the sleeve 554 is stopped. As a result, the supply of hydrogen fuel from the sleeve 554 to the intake passage 63 is stopped. In other words, the sleeve 554 stops injection of hydrogen fuel.

More specifically, when hydrogen fuel is burned in the combustion chamber 61, that is, in the hydrogen fuel mode, the valve 551 intermittently supplies hydrogen fuel into the engine 1 by repeatedly opening and closing the hydrogen fuel passage 555. supply. That is, in the hydrogen fuel mode, the valve 551 intermittently supplies hydrogen fuel into the engine 1 by alternately repeating the open state and the closed state.

For example, valve 551 includes a housing 552 and a driver 553. Housing 552 has a flow path 555. The flow path 555 is connected to the flow path 110 of the hydrogen fuel supply pipe 10X. The driver 553 opens and closes the flow path 555 by moving within the housing 552 in the opening direction D1 and the closing direction D2. The opening direction D1 indicates, for example, a vertically upward direction. The closing direction D2 indicates, for example, a vertically downward direction.

Specifically, the driver 553 opens the flow path 555 by moving in the opening direction D1. Therefore, the flow path 110 of the hydrogen fuel supply pipe 10X communicates with the flow path 556 of the sleeve 554 via the flow path 555. As a result, as shown by the arrow SL, hydrogen fuel from the hydrogen fuel supply pipe 10X flows into the flow path 556 through the flow path 555 and is injected from the sleeve 554. On the other hand, the driver 553 closes the flow path 555 by moving in the closing direction D2. In other words, the flow path 555 is blocked. Therefore, hydrogen fuel is not injected from sleeve 554.

More specifically, in the hydrogen fuel mode, the driving body 553 alternately moves in the opening direction D1 and moves in the closing direction D2, thereby repeatedly opening and closing the channel 555. As a result, sleeve 554 intermittently injects hydrogen fuel.

In this embodiment, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the valve 551 opens the hydrogen fuel flow path 555 by opening the hydrogen fuel supply pipe 10X. 10X and the inside of the engine 1 (the intake passage 63 in the example of FIG. 2) are communicated with each other. That is, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the driver 553 moves in the opening direction D1 to open the hydrogen fuel flow path 555 and connect the hydrogen fuel supply pipe 10X and the engine 1. communicates with the inside of the Therefore, as shown by the arrow DL, air supplied by the supercharger 11 is introduced into the hydrogen fuel supply pipe 10X through the flow path 556 of the sleeve 554 and the flow path 555 of the valve 551. As a result, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is discharged to the outside from the discharge pipe 73 by air at a pressure higher than atmospheric pressure while the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. be done.

Specifically, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the valve 551 (specifically, the driving body 553) is configured so that the fuel flow rate adjustment section 71 supplies hydrogen fuel to the hydrogen fuel supply pipe 10X. By continuing the operation of repeating the open state and the closed state before shutting off the hydrogen fuel flow path 555, the hydrogen fuel supply pipe 10X and the inside of the engine 1 (the example in FIG. The intake passage 63) is intermittently communicated with the intake passage 63). That is, when discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the valve 551 (specifically, the driver 553) causes the fuel flow rate adjustment section 71 to cut off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X. The operation of alternately repeating the communication state and the cutoff state between the hydrogen fuel supply pipe 10X and the inside of the engine 1 is continued from before. Therefore, when the fuel flow rate adjustment unit 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X, air supplied by the supercharger 11 is intermittently supplied to the hydrogen fuel supply pipe 10X, as shown by the arrow DL. will be introduced.

Returning to FIG. 1, the entrance of the exhaust passage 64 is connected to the combustion chamber 61. The outlet of the exhaust passage 64 is connected to the exhaust pipe 19. Therefore, exhaust gas from the combustion chamber 61 is discharged into the exhaust pipe 19 through the exhaust passage 64. Specifically, the exhaust valve 54 is arranged at the entrance of the exhaust passage 64. The exhaust valve 54 opens or closes the entrance of the exhaust passage 64. When the exhaust valve 54 opens the inlet of the exhaust passage 64, exhaust gas is discharged through the exhaust passage 64 into the exhaust pipe 19.

The liquid fuel supply section 56 supplies liquid fuel toward the combustion chamber 61 in the liquid fuel mode. For example, the liquid fuel supply section 56 injects liquid fuel toward the combustion chamber 61. The liquid fuel supplied by the liquid fuel supply section 56 is liquid fuel that is burned to drive the engine 1 (specifically, the piston 58). The liquid fuel is, for example, light oil or heavy oil. The liquid fuel supply section 56 is, for example, a liquid fuel injector. The liquid fuel injector is, for example, a main injection valve.

The ignition inducing unit 57 injects into the combustion chamber 61 liquid fuel that induces ignition of the hydrogen fuel supplied to the combustion chamber 61 by the hydrogen fuel supply unit 55 in the hydrogen fuel mode. Further, the ignition inducing unit 57 injects into the combustion chamber 61 liquid fuel that induces ignition of the liquid fuel supplied to the combustion chamber 61 by the liquid fuel supply unit 56 in the liquid fuel mode.

The amount of liquid fuel injected by the ignition inducing section 57 in the hydrogen fuel mode and the liquid fuel mode is smaller than the amount of liquid fuel supplied by the liquid fuel supply section 56 in the liquid fuel mode. This is because the amount of liquid fuel injected by the ignition inducing section 57 is sufficient to induce ignition of the hydrogen fuel and ignition of the liquid fuel. Hereinafter, the liquid fuel injected by the ignition inducer 57 may be referred to as "pilot fuel." The pilot fuel is, for example, light oil or heavy oil. The type of pilot fuel is, for example, the same type as the liquid fuel supplied by the liquid fuel supply section 56. The ignition inducer 57 is, for example, a pilot fuel injector. The pilot fuel injector is, for example, a pilot fuel injection valve. Further, the ignition inducer 57 may be, for example, a "spark plug" that ignites with a spark or a laser.

Note that even if the liquid fuel can be ignited without injecting the pilot fuel in the liquid fuel mode, the ignition inducer 57 injects the pilot fuel in the liquid fuel mode. This is to prevent the ignition inducing portion 57 from being damaged due to combustion of the liquid fuel.

The cylinder block 52 constitutes the cylinder 1a. Cylinder block 52 accommodates piston 58, connecting rod 59, and crankshaft 60. The piston 58 reciprocates up and down inside the cylinder block 52. Connecting rod 59 connects piston 58 and crankshaft 60. The connecting rod 59 transmits the reciprocating motion of the piston 58 to the crankshaft 60. Crankshaft 60 converts the reciprocating motion of piston 58 into rotational motion.

For example, in the hydrogen fuel mode, when the piston 58 descends and the intake valve 53 opens with the exhaust valve 54 closed, hydrogen fuel mixed with air is supplied from the intake passage 63 to the combustion chamber 61. That is, the hydrogen fuel supply section 55 injects hydrogen fuel at the timing when the intake valve 53 opens. Next, with the exhaust valve 54 and the intake valve 53 closed, the piston 58 rises. Next, at the top dead center of the piston 58, the ignition inducer 57 injects pilot fuel, and the hydrogen fuel ignites and burns. As a result, the piston 58 descends due to combustion. Next, the piston 58 rises, and the exhaust valve 54 opens while the intake valve 53 is closed. As a result, exhaust gas is discharged from the combustion chamber 61 to the exhaust passage 64.

For example, in the liquid fuel mode, when the piston 58 descends and the intake valve 53 opens with the exhaust valve 54 closed, air is supplied from the intake passage 63 to the combustion chamber 61. Next, with the exhaust valve 54 and the intake valve 53 closed, the piston 58 rises. Next, at the top dead center of the piston 58, the liquid fuel supply section 56 injects liquid fuel, and the ignition induction section 57 injects pilot fuel. Therefore, the liquid fuel ignites and burns. As a result, the piston 58 descends due to combustion. Next, the piston 58 rises, and the exhaust valve 54 opens while the intake valve 53 is closed. As a result, exhaust gas is discharged from the combustion chamber 61 to the exhaust passage 64.

The engine rotation speed detection unit 62 detects the rotation speed of the engine 1 per unit time. The engine rotation speed detection unit 62 is, for example, an engine rotation speed sensor. The engine rotation speed sensor includes, for example, a sensor and a pulse generator, and generates a pulse signal according to the rotation of the crankshaft 60.

Next, engine system 100 will be explained with reference to FIG. FIG. 3 is a block diagram showing the engine system 100. As shown in FIG. 3, the engine system 100 further includes an engine control device 21 and an operation control device 23.

The operation control device 23 receives an operation from an operator, and outputs an operation signal to the engine control device 21 according to the operation from the operator.

The operation control device 23 includes, for example, an input device, a display device, and a computer. Input devices include, for example, keyboards, pointing devices, dials, and push buttons. The display device is, for example, a liquid crystal display. The display device may include, for example, a touch panel. A computer includes, for example, a processor and a storage device. The processor includes, for example, a CPU (Central Processing Unit). The storage device stores data and computer programs. The storage device includes, for example, a main storage device such as a semiconductor memory, and an auxiliary storage device such as a semiconductor memory and a hard disk drive. The storage device may include removable media. The operation control device 23 is, for example, an operation control panel.

Engine control device 21 controls engine 1 . For example, the engine control device 21 controls the engine 1 according to the operation signal output by the operation control device 23. Further, for example, the engine control device 21 controls the engine 1 according to a computer program.

The engine control device 21 controls, for example, a hydrogen fuel supply section 55, a liquid fuel supply section 56, and an ignition induction section 57. Further, the engine control device 21 controls the hydrogen fuel adjustment section 7. For example, the engine control device 21 controls the fuel flow rate adjustment section 71 and the fuel discharge section 72. Furthermore, the engine control device 21 receives information indicating the pressure of the gas within the hydrogen fuel supply pipe 10 from the pressure detection unit 9 .

Engine control device 21 is, for example, a computer. The computer is, for example, an ECU (Electronic Control Unit). Specifically, engine control device 21 includes a control section 211 and a storage section 212. The control unit 211 includes a processor such as a CPU. The storage unit 212 includes a storage device and stores data and computer programs. The storage device includes, for example, a main storage device such as a semiconductor memory and an auxiliary storage device. The storage device may include removable media.

The control unit 211 controls the engine 1 and the hydrogen fuel adjustment unit 7. Specifically, the control section 211 controls the hydrogen fuel supply section 55, the liquid fuel supply section 56, the ignition induction section 57, the fuel flow rate adjustment section 71, and the fuel discharge section 72. More specifically, the processor of the control unit 211 controls the hydrogen fuel supply unit 55, the liquid fuel supply unit 56, the ignition induction unit 57, and the fuel flow rate by executing a computer program stored in the storage device of the storage unit 212. Controls the adjustment section 71 and the fuel discharge section 72.

When stopping the engine 1 from the hydrogen fuel mode, the control unit 211 introduces air at a pressure higher than atmospheric pressure into the hydrogen fuel supply pipe 10 while the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. The hydrogen fuel supply section 55 is controlled as follows. In addition, when stopping the engine 1 from the hydrogen fuel mode, the control unit 211 controls the fuel so that the hydrogen fuel is discharged from the hydrogen fuel supply pipe 10 in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. Controls the discharge section 72. As a result, it is possible to effectively suppress hydrogen fuel from remaining in the hydrogen fuel supply pipe 10 after the engine 1 is stopped from the hydrogen fuel mode.

The case where the engine 1 is stopped refers to the case where the engine stop condition is satisfied. The engine stop condition indicates a condition for stopping the engine 1. The engine stop condition is, for example, that the control unit 211 has received an engine stop instruction to stop the engine 1 from the operation control device 23 . Alternatively, the engine stop condition is, for example, that the control unit 211 has determined to stop the engine 1 based on the state of the engine 1 by executing calculations according to a computer program.

Further, when shifting from the hydrogen fuel mode to the liquid fuel mode, the control unit 211 supplies air at a pressure higher than atmospheric pressure to the hydrogen fuel supply pipe 10X in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. The hydrogen fuel supply section 55 is controlled so that the hydrogen fuel is introduced into the hydrogen fuel. In addition, when transitioning from the hydrogen fuel mode to the liquid fuel mode, the control unit 211 discharges hydrogen fuel from the hydrogen fuel supply pipe 10 in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. Controls the fuel discharge section 72. As a result, it is possible to effectively suppress hydrogen fuel from remaining in the hydrogen fuel supply pipe 10 after transitioning from the hydrogen fuel mode to the liquid fuel mode.

The case of transitioning from the hydrogen fuel mode to the liquid fuel mode refers to the case where the liquid fuel mode transition conditions are satisfied. The liquid fuel mode transition conditions indicate conditions for transitioning the operating mode of the engine 1 from the hydrogen fuel mode to the liquid fuel mode. The liquid fuel mode transition condition is, for example, that the control unit 211 receives a transition instruction from the operation control device 23 to transition from the hydrogen fuel mode to the liquid fuel mode. Alternatively, the liquid fuel mode transition condition may be, for example, when the control unit 211 executes calculation according to a computer program to cause the operation mode to transition from the hydrogen fuel mode to the liquid fuel mode based on the state of the engine 1. This has been decided.

If hydrogen fuel remains in the hydrogen fuel supply pipe 10X when the engine 1 is stopped from the hydrogen fuel mode or when the engine 1 is switched from the hydrogen fuel mode to the liquid fuel mode, the size of the hydrogen molecules is small, so the hydrogen molecules Hydrogen molecules may gradually leak out from joints between parts, or hydrogen molecules may leak out from various valves if they are not sufficiently sealed. In this case, hydrogen molecules may flow into or remain at unexpected locations in the engine 1 due to various factors. Therefore, in this embodiment, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is diluted by discharging the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X with air at a pressure higher than atmospheric pressure, so that hydrogen molecules flow into and remain in unpredictable places in the engine 1. prevent Furthermore, if hydrogen molecules flow into or remain in an unexpected location in the engine 1, for example, the hydrogen molecules will be affected by static electricity generated when the engine 1 is restarted, or by high heat caused by exhaust gas when the engine 1 is operated. there is a possibility.

Next, with reference to FIG. 4, residual hydrogen discharge control when stopping the engine 1 in the hydrogen fuel mode will be described. Residual hydrogen discharge control indicates control for discharging hydrogen remaining in the hydrogen fuel supply pipe 10X by the hydrogen fuel supply section 55 and the hydrogen fuel adjustment section 7.

FIG. 4 is a time chart showing changes in various states of the engine system 100 when the engine 1 is stopped in the hydrogen fuel mode.

In FIG. 4, the horizontal axes of charts CT1 to CT8 indicate time. The vertical axis of chart CT1 indicates the state of engine 1, the vertical axis of chart CT2 indicates the state of fuel flow rate adjustment section 71 (open state or closed state), and the vertical axis of chart CT3 indicates the state of hydrogen fuel supply section 55. (open or closed state). The vertical axis of chart CT4 indicates the amount of hydrogen in the hydrogen fuel supply pipe 10X, the vertical axis of chart CT5 indicates the amount of liquid fuel supplied by liquid fuel supply section 56, and the vertical axis of chart CT6 indicates the amount of hydrogen supplied by ignition induction section 57. Indicates the amount of fuel injected. The vertical axis of chart CT7 indicates the state of fuel discharge section 72 (open state or closed state), and the vertical axis of chart CT8 indicates the pressure of gas within hydrogen fuel supply pipe 10X.

As shown in FIG. 4, the state of engine system 100 before time t1 is as follows. That is, as shown in chart CT1, engine 1 is operated in hydrogen fuel mode. Therefore, as shown in chart CT2, fuel flow rate adjustment section 71 is in an open state. Therefore, hydrogen fuel is supplied from the vaporizer 5 to the hydrogen fuel supply pipe 10X. As a result, as shown in chart CT4, the amount of hydrogen in the hydrogen fuel supply pipe 10X is maintained substantially constant. Similarly, as shown in chart CT8, the pressure of the gas (hydrogen fuel) in the hydrogen fuel supply pipe 10X is maintained substantially constant. Further, as shown in chart CT3, the hydrogen fuel supply section 55 intermittently supplies hydrogen fuel to the combustion chamber 61 of the engine 1 by repeating opening and closing. Further, as shown in chart CT6, the ignition induction section 57 intermittently injects pilot fuel into the combustion chamber 61 of the engine 1 by repeatedly opening and closing. Therefore, as shown in chart CT1, engine 1 is driven by combustion of hydrogen fuel in combustion chamber 61. In this case, the engine 1 rotates at a constant rotational speed, for example. On the other hand, as shown in chart CT7, the fuel discharge section 72 is in a closed state. Therefore, the flow path of the discharge pipe 73 is closed. Further, as shown in chart CT5, the liquid fuel supply unit 56 has stopped supplying liquid fuel.

Next, at time t1, the engine stop condition is satisfied. For example, at time t1, the control unit 211 receives an engine stop instruction. As a result, the engine 1 starts the cooling mode at time t1, as shown in chart CT1. The cooling mode is a mode in which the engine 1 performs no-load operation, and is a mode in which the engine 1 is cooled before the engine 1 is stopped.

Even if the engine stop condition is satisfied at time t1, the control unit 211 controls the hydrogen fuel supply unit 55 so that the hydrogen fuel supply unit 55 continues to repeat opening and closing from before time t1, as shown in chart CT3. is under control.

In response to the engine stop condition being satisfied at time t1, as shown in chart CT2, the control unit 211 closes the fuel flow rate adjustment unit 71 to stop the flow of hydrogen fuel into the hydrogen fuel supply pipe 10X. Cut off the supply. Therefore, at time t1, as shown in charts CT4 and CT8, the amount of hydrogen and the gas pressure (hydrogen pressure) in the hydrogen fuel supply pipe 10X begin to decrease. As a result, at time t1, for example, the rotation speed of the engine 1 starts to decrease. Further, at time t1, the control unit 211 controls the liquid fuel supply unit 56 so that the liquid fuel supply unit 56 starts supplying liquid fuel to the combustion chamber 61 of the engine 1, as shown in chart CT5. Furthermore, as shown in chart CT6, even after time t1, the ignition inducer 57 continues to intermittently inject pilot fuel into the combustion chamber 61 of the engine 1 by repeating opening and closing.

During the period T1 from time t1 to time t2, as shown in chart CT3, the hydrogen fuel supply section 55 opens and closes, so that the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is supplied to the combustion chamber 61 and burned. . In addition, during the period T1, the control unit 211 controls the liquid fuel supply unit 56 so that the liquid fuel supply unit 56 increases the supply amount of liquid fuel toward the target supply amount Q1, as shown in chart CT5. . Therefore, during the period T1, liquid fuel is also burned in the combustion chamber 61. As a result, even though the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off, the engine 1 maintains the rotational speed constant during the period T1. Note that, as shown in chart CT6, the intermittent injection of pilot fuel continues during period T1 as well.

That is, in this embodiment, in order to maintain the rotational speed of the engine 1 constant in the cooling mode, not only liquid fuel but also hydrogen fuel is combusted during the period T1 of the cooling mode. As a result, the amount of liquid fuel supplied in the cooling mode can be reduced. In addition, by burning the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X during the cooling mode period T1, the amount of hydrogen fuel discharged from the hydrogen fuel supply pipe 10X to the outside (for example, the engine room) after time t2 is reduced. Can be reduced.

Here, in this specification, when the rotational speed of the engine 1 is maintained constant, the rotational speed that is maintained constant is not particularly limited, and may be any rotational speed.

Next, at time t2, the control section 211 controls the fuel discharge section 72 so that the fuel discharge section 72 is in an open state, as shown in chart CT7. Therefore, the fuel discharge part 72 is in an open state and the discharge pipe 73 is opened. In addition, as shown in chart CT3, the control unit 211 controls the hydrogen fuel supply unit 55 so that the hydrogen fuel supply unit 55 continues to repeat opening and closing from before time t2. As a result, as shown in chart CT4, during the period T2 from time t2 to time t3, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is introduced into the hydrogen fuel supply pipe 10X via the hydrogen fuel supply section 55. Air (specifically, air at a pressure higher than atmospheric pressure) is discharged to the outside from the discharge pipe 73. Further, in period T2, as shown in chart CT8, the pressure of the gas (mixture of air and hydrogen) in the hydrogen fuel supply pipe 10X becomes approximately constant. The pressure of the gas inside the hydrogen fuel supply pipe 10X during the period T2 is lower than the pressure of the gas inside the hydrogen fuel supply pipe 10X during the period T1.

In period T2, as shown in chart CT3, hydrogen fuel supply section 55 repeats opening and closing, but hydrogen fuel supply section 55 does not supply hydrogen fuel to combustion chamber 61. This is because air at a pressure higher than atmospheric pressure is flowing from the hydrogen fuel supply section 55 toward the hydrogen fuel supply pipe 10X. Further, in period T2, as shown in chart CT5, the control unit 211 controls the liquid fuel supply unit 56 so that the amount of liquid fuel supplied by the liquid fuel supply unit 56 is maintained at the target supply amount Q1. Therefore, during the period T2 of the cooling mode, the rotation speed of the engine 1 is maintained constant only by combustion of the liquid fuel. The target supply amount Q1 indicates the amount of liquid fuel that can maintain the rotational speed of the engine 1 constant only by burning the liquid fuel. Note that, as shown in chart CT6, the intermittent injection of pilot fuel continues during period T2 as well.

Next, at time t3, the control section 211 controls the fuel discharge section 72 so that the fuel discharge section 72 is in the closed state, as shown in chart CT7. Therefore, the fuel discharge part 72 is in a closed state and blocks the discharge pipe 73. Further, at time t3, the control unit 211 controls the hydrogen fuel supply unit 55 so that the hydrogen fuel supply unit 55 is in a closed state, as shown in chart CT3. Therefore, the introduction of air from the hydrogen fuel supply section 55 to the hydrogen fuel supply pipe 10X is stopped. As a result, as shown in chart CT8, at time t3, the pressure of the gas (air) in the hydrogen fuel supply pipe 10X becomes approximately the same as the atmospheric pressure. Note that, for example, the rotation speed of the engine 1 is maintained constant by the liquid fuel from the liquid fuel supply section 56 even during the period from time t3 to time t4.

Next, at time t4, as shown in chart CT5, the control unit 211 controls the liquid fuel supply unit 56 so that the liquid fuel supply unit 56 stops supplying liquid fuel. In addition, at time t4, the control unit 211 controls the ignition inducer 57 so that the ignition inducer 57 stops supplying the pilot fuel, as shown in chart CT6. As a result, at time t4, the cooling mode ends and the engine 1 stops. That is, at time T4, the rotation speed of the engine 1 becomes zero.

As described above with reference to charts CT2, CT7, and CT5 in FIG. 4, according to the present embodiment, when stopping the engine 1 from the hydrogen fuel mode, the fuel flow rate adjustment unit 71 The control unit 211 controls the supply of liquid fuel by the liquid fuel supply unit 56 so that the rotation speed of the engine 1 is maintained constant after the supply of hydrogen fuel to the engine 1 is cut off (after time t1). Therefore, after the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off, the engine 1 can be cooled and then stopped. That is, after the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off, it is possible to smoothly shift to the cooling mode.

As an example, when the engine 1 maintains the rotational speed constant after the fuel flow rate adjustment unit 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X, the fuel flow rate adjustment unit 71 cuts off the supply of hydrogen fuel. The subsequent rotational speed of the engine 1 may be maintained at the rotational speed of the engine 1 before the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel. Alternatively, as an example, when the engine 1 maintains the rotational speed constant after the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X, the fuel flow rate adjustment section 71 stops the supply of hydrogen fuel. The rotational speed of the engine 1 after the cutoff may be lower than the rotational speed of the engine 1 before the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel.

Further, as shown in charts CT7 and CT3, the control unit 211 controls the hydrogen fuel supply unit 55 to be in the closed state after a predetermined time T2 has elapsed since the fuel discharge unit 72 started discharging hydrogen fuel. The hydrogen fuel supply section 55 is controlled (time t3). That is, the control unit 211 causes the hydrogen fuel supply unit 55 to close the hydrogen fuel flow path 555 (FIG. 2) after the predetermined time T2 has elapsed since the fuel discharge unit 72 started discharging hydrogen fuel. Controls the hydrogen fuel supply section 55. Therefore, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is continuously discharged from the discharge pipe 73 for the predetermined time T2. As a result, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X can be discharged more effectively. The predetermined time T2 is predetermined based on the channel volume of the hydrogen fuel supply pipe 10X.

Note that, for example, in the hydrogen fuel mode, the control unit 211 changes the opening time and/or opening/closing interval of the hydrogen fuel supply unit 55 according to the rotation speed of the engine 1. Furthermore, the rotational speed of the engine 1 may be approximately the same or different between the hydrogen fuel mode and the cooling mode, for example. Furthermore, the rotation speed of the engine 1 does not have to be kept constant, for example in hydrogen fuel mode, but may vary. Furthermore, the rotation speed of the engine 1 does not need to be kept constant, for example in the cooling mode, and may vary.

Next, with reference to FIGS. 3 and 5, a method for discharging residual hydrogen when stopping the engine 1 in the hydrogen fuel mode will be described. FIG. 5 is a flowchart showing a method for discharging residual hydrogen when stopping the engine 1 in the hydrogen fuel mode. As shown in FIG. 5, the method for discharging residual hydrogen includes steps S1 to S8. Furthermore, at the stage of step S1, the engine 1 is operating in hydrogen fuel mode. Therefore, in step S1, the hydrogen fuel supply section 55 repeats opening and closing to intermittently supply hydrogen fuel to the combustion chamber 61. Similarly, the ignition induction section 57 also repeats opening and closing to intermittently supply pilot fuel to the combustion chamber 61.

As shown in FIGS. 3 and 5, first, in step S1, the control unit 211 determines whether an engine stop condition is satisfied.

If it is determined in step S1 that the engine stop condition is not satisfied (No), the process ends.

On the other hand, if it is determined in step S1 that the engine stop condition is satisfied (Yes), the process proceeds to step S2.

Next, in step S2, the control unit 211 controls the liquid fuel supply unit 56 to start the cooling mode. Note that the control unit 211 may start the cooling mode in response to a manual operation.

Next, in step S3, the control unit 211 controls the fuel flow rate adjustment unit 71 to be in the closed state. That is, the control unit 211 controls the fuel flow rate adjustment unit 71 to cut off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X.

Here, step S2 and step S3 may be executed substantially simultaneously (see time t1 in FIG. 4).

Next, in step S4, the control unit 211 determines whether the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is less than the threshold value TH. In this case, the control unit 211 acquires information indicating the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X from the pressure detection unit 9.

If it is determined in step S4 that the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is not less than the threshold TH (No), until the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X becomes less than the threshold TH, Step S4 is repeated.

On the other hand, if it is determined in step S4 that the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is less than the threshold TH (Yes), the process proceeds to step S5. The fact that the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is less than the threshold value TH means that, for example, during period T1 (FIG. 4), the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is burned in the combustion chamber 61, and the hydrogen fuel is This indicates that the amount of hydrogen fuel remaining in the supply pipe 10X has decreased to the target amount.

Next, in step S5, the control section 211 controls the fuel discharge section 72 to be in the open state. That is, the control unit 211 controls the fuel exhaust unit 72 to open the exhaust pipe 73.

Next, in step S6, the control section 211 determines whether a predetermined time T2 has elapsed since the fuel discharge section 72 was opened. That is, the control unit 211 determines whether the predetermined time T2 has elapsed since the fuel discharge unit 72 started discharging hydrogen fuel.

If it is determined in step S6 that the predetermined time T2 has not elapsed (No), step S6 is repeated until the predetermined time T2 has elapsed.

On the other hand, if it is determined in step S6 that the predetermined time T2 has elapsed (Yes), the process proceeds to step S7.

Next, in step S7, the control unit 211 controls the hydrogen fuel supply unit 55 to be in the closed state. That is, the control unit 211 controls the hydrogen fuel supply unit 55 to close the hydrogen fuel flow path 555 (FIG. 2). Further, in step S7, the control section 211 controls the fuel discharge section 72 to be in the closed state. That is, the control section 211 controls the fuel discharge section 72 to close the discharge pipe 73.

Here, the timing at which the hydrogen fuel supply section 55 is closed and the timing at which the fuel discharge section 72 is closed may be different. For example, the fuel discharge section 72 may be closed after the hydrogen fuel supply section 55 is closed.

Next, in step S8, the control unit 211 controls the liquid fuel supply unit 56 to end the cooling mode. As a result, engine 1 stops. The residual hydrogen evacuation method then ends.

Here, step S8 and step S7 may be executed substantially simultaneously.

As described above with reference to FIG. 5, according to the present embodiment, after the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel, the pressure of the gas (hydrogen) present in the hydrogen fuel supply pipe 10X becomes less than the threshold TH, the control unit 211 controls the fuel discharge unit 72 to start discharging hydrogen fuel from the hydrogen fuel supply pipe 10X (step S5, time t2 in FIG. 4). Therefore, according to the present embodiment, hydrogen fuel is supplied to the combustion chamber 61 until the pressure of the gas (hydrogen) present in the hydrogen fuel supply pipe 10X becomes less than the threshold value TH. Therefore, hydrogen fuel can be consumed without waste. Further, by consuming the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X without waste, the amount of hydrogen fuel discharged from the hydrogen fuel supply pipe 10X through the discharge pipe 73 can be reduced.

Next, with reference to FIG. 6, residual hydrogen discharge control upon transition from hydrogen fuel mode to liquid fuel mode will be described.

FIG. 6 is a time chart showing changes in various states of engine system 100 when transitioning from hydrogen fuel mode to liquid fuel mode.

In FIG. 6, the horizontal axes of charts CT10 to CT80 indicate time. The vertical axes of charts CT10 to CT80 are the same as the vertical axes of charts CT1 to CT8 shown in FIG. 4, respectively. Furthermore, in the explanation of FIG. 4, the explanation of FIG. 6 can be substituted by appropriately reading chart CT1 to chart CT8 as chart CT10 to chart CT80, respectively. Hereinafter, with reference to FIG. 6, differences from FIG. 4 will be mainly explained.

As shown in charts CT10 to CT80 of FIG. 6, the state of engine system 100 before time t1 is similar to the state of engine system 100 shown in FIG. 4.

Next, at time t1, the liquid fuel mode transition condition is satisfied. For example, at time t1, the control unit 211 receives a transition instruction to transition from hydrogen fuel mode to liquid fuel mode. As shown in chart CT50, changeover control is started at time t1 in response to the liquid fuel mode shift condition being satisfied. The changeover control is control for causing the liquid fuel supply unit 56 to increase the amount of liquid fuel supplied toward the target supply amount Q1. The target supply amount Q1 indicates the amount of liquid fuel that can maintain the rotational speed of the engine 1 constant only by burning the liquid fuel. In other words, the target supply amount Q1 indicates the amount of liquid fuel supplied that can maintain the rotational speed of the engine 1 before shifting to the liquid fuel mode after shifting to the liquid fuel mode. In the example of FIG. 6, changeover control is executed during period T1.

Even if the liquid fuel mode transition condition is satisfied at time t1, the control unit 211 controls the hydrogen fuel supply so that the hydrogen fuel supply unit 55 continues to repeat opening and closing from before time t1, as shown in chart CT30. 55.

In response to the liquid fuel mode transition condition being satisfied at time t1, as shown in chart CT20, the control unit 211 closes the fuel flow rate adjustment unit 71 to stop hydrogen from flowing into the hydrogen fuel supply pipe 10X. Cut off fuel supply. Therefore, at time t1, as shown in charts CT40 and CT80, the amount of hydrogen and the gas pressure (hydrogen pressure) in the hydrogen fuel supply pipe 10X begin to decrease. However, since changeover control is executed, for example, the rotation speed of the engine 1 is maintained constant. That is, at time t1, the control unit 211 controls the liquid fuel supply unit 56 so that the liquid fuel supply unit 56 starts supplying liquid fuel to the combustion chamber 61 of the engine 1, as shown in chart CT50. As a result, changeover control is started.

During the period T1 from time t1 to time t2, the control unit 211 controls the liquid fuel supply unit so that the liquid fuel supply unit 56 increases the supply amount of liquid fuel toward the target supply amount Q1, as shown in chart CT50. 56. Additionally, during period T1, as shown in chart CT30, hydrogen fuel supply section 55 opens and closes, so that the hydrogen fuel remaining in hydrogen fuel supply pipe 10X is supplied to combustion chamber 61 and burned. Therefore, during period T1, not only liquid fuel but also hydrogen fuel is burned. Therefore, during the period T1 during which the changeover control is executed, for example, the engine 1 maintains the rotational speed constant.

That is, in this embodiment, in order to maintain the rotational speed of the engine 1 constant during changeover control, not only liquid fuel but also hydrogen fuel is combusted during period T1. As a result, the amount of liquid fuel supplied during changeover control can be reduced. Furthermore, by burning the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X during the period T1, the amount of hydrogen fuel discharged from the hydrogen fuel supply pipe 10X to the outside (for example, the engine room) after time t2 can be reduced.

Next, at time t2, the operations of the fuel discharge section 72 and the hydrogen fuel supply section 55 shown by charts CT70 and CT30 are the same as those shown in charts CT7 and CT3 shown in FIG. 4, respectively. Therefore, as shown in chart CT40, in period T2, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is replaced by air (specifically, atmospheric pressure) introduced into the hydrogen fuel supply pipe 10X via the hydrogen fuel supply section 55. air at a higher pressure) is discharged to the outside from the discharge pipe 73.

Further, as shown in chart CT50, changeover control ends at time t2. After time t2, the control unit 211 controls the liquid fuel supply unit 56 so that the amount of liquid fuel supplied by the liquid fuel supply unit 56 is maintained at the target supply amount Q1, as shown in chart CT50. In addition, as shown in chart CT60, intermittent injection of pilot fuel continues after time t2. As a result, after time t2, the rotational speed of the engine 1 is maintained constant, for example, only by combustion of the liquid fuel. That is, the liquid fuel mode is started at time t2, and for example, the rotation speed of the engine 1 is maintained constant in the liquid fuel mode.

Next, at time t3, the operations of the fuel discharge section 72 and the hydrogen fuel supply section 55 shown by charts CT70 and CT30 are the same as those shown in charts CT7 and CT3 shown in FIG. 4, respectively. Therefore, at time t3, the introduction of air from the hydrogen fuel supply section 55 to the hydrogen fuel supply pipe 10X is stopped, and the discharge of the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X is completed.

As described above with reference to FIG. 6, as an example, the rotation speed of the engine 1 is maintained constant in the hydrogen fuel mode, the changeover control period T1, and the liquid fuel mode.

Further, according to the present embodiment, for example, when transitioning from the hydrogen fuel mode to the liquid fuel mode, the rotation speed of the engine 1 is constant before and after the fuel flow rate adjustment section 71 cuts off the supply of hydrogen fuel. The control unit 211 controls the supply of liquid fuel by the liquid fuel supply unit 56 so that the current level is maintained (after time t1). Therefore, the hydrogen fuel mode can be smoothly shifted to the liquid fuel mode without any fluctuation in the output of the engine 1.

Also, when shifting from the hydrogen fuel mode to the liquid fuel mode, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X continues for a predetermined period of time T2 and is discharged from the discharge pipe, as in the case of stopping the engine 1 from the hydrogen fuel mode. It is discharged from 73. As a result, the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X can be discharged more effectively.

Note that, for example, in the hydrogen fuel mode, the control unit 211 changes the opening time and/or opening/closing interval of the hydrogen fuel supply unit 55 according to the rotation speed of the engine 1. Similarly, for example, in the liquid fuel mode, the control unit 211 changes the opening time and opening/closing interval of the liquid fuel supply unit 56 according to the rotation speed of the engine 1. Further, the rotational speed of the engine 1 may be approximately the same or different between, for example, the hydrogen fuel mode, the changeover control, and the liquid fuel mode. Furthermore, the rotation speed of the engine 1 does not have to be kept constant, for example in hydrogen fuel mode, but may vary. Furthermore, the rotational speed of the engine 1 does not need to be kept constant and may vary, for example, in changeover control. Furthermore, the rotation speed of the engine 1 does not have to be kept constant, for example in liquid fuel mode, but may vary.

Next, with reference to FIGS. 3 and 7, a method for discharging residual hydrogen when transitioning from hydrogen fuel mode to liquid fuel mode will be described. FIG. 7 is a flowchart showing a method for discharging residual hydrogen when transitioning from hydrogen fuel mode to liquid fuel mode. As shown in FIG. 7, the residual hydrogen discharge method includes steps S11 to S19. Furthermore, at the stage of step S11, the engine 1 is operating in the hydrogen fuel mode. Therefore, in step S11, the hydrogen fuel supply section 55 repeats opening and closing to intermittently supply hydrogen fuel to the combustion chamber 61. Similarly, the ignition induction section 57 also repeats opening and closing to intermittently supply pilot fuel to the combustion chamber 61.

As shown in FIGS. 3 and 7, first, in step S11, the control unit 211 determines whether the liquid fuel mode transition condition is satisfied.

If it is determined in step S11 that the liquid fuel mode transition condition is not satisfied (No), the process ends.

On the other hand, if it is determined in step S11 that the liquid fuel mode transition condition is satisfied (Yes), the process proceeds to step S12.

Next, in step S12, the control unit 211 controls the liquid fuel supply unit 56 to start changeover control.

Next, in step S13, the control unit 211 controls the fuel flow rate adjustment unit 71 to be in the closed state. That is, the control unit 211 controls the fuel flow rate adjustment unit 71 to cut off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X.

Here, step S12 and step S13 may be executed substantially simultaneously (see time t1 in FIG. 6).

Next, in step S14, the control unit 211 determines whether the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is less than the threshold value TH.

If it is determined in step S14 that the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is not less than the threshold TH (No), until the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X becomes less than the threshold TH, Step S14 is repeated.

On the other hand, if it is determined in step S14 that the pressure of the gas (hydrogen) in the hydrogen fuel supply pipe 10X is less than the threshold TH (Yes), the process proceeds to step S15.

Next, in step S15, the control unit 211 controls the liquid fuel supply unit 56 and ends the changeover control.

Next, in step S16, the control unit 211 controls the liquid fuel supply unit 56 to start the liquid fuel mode. That is, the control unit 211 controls the liquid fuel supply unit 56 so that the supply amount of liquid fuel is maintained at the target supply amount Q1.

Here, step S15 and step S16 may be executed substantially simultaneously (see time t2 in FIG. 6).

Next, in step S17, the control section 211 controls the fuel discharge section 72 to be in the open state. That is, the control unit 211 controls the fuel exhaust unit 72 to open the exhaust pipe 73.

Here, step S17 may be executed substantially simultaneously with step S15 and step S16 (see time t2 in FIG. 6), or may be executed after step S14 and before step S15 and step S16.

Next, in step S18, the control section 211 determines whether a predetermined time T2 has elapsed since the fuel discharge section 72 was opened. That is, the control unit 211 determines whether the predetermined time T2 has elapsed since the fuel discharge unit 72 started discharging hydrogen fuel.

If it is determined in step S18 that the predetermined time T2 has not elapsed (No), step S18 is repeated until the predetermined time T2 has elapsed.

On the other hand, if it is determined in step S18 that the predetermined time T2 has elapsed (Yes), the process proceeds to step S19.

Next, in step S19, the control unit 211 controls the hydrogen fuel supply unit 55 to be in the closed state. That is, the control unit 211 controls the hydrogen fuel supply unit 55 to close the hydrogen fuel flow path 555 (FIG. 2). Furthermore, in step S19, the control section 211 controls the fuel discharge section 72 to be in the closed state. That is, the control section 211 controls the fuel discharge section 72 to close the discharge pipe 73. The residual hydrogen evacuation method then ends.

Here, the timing at which the hydrogen fuel supply section 55 is closed and the timing at which the fuel discharge section 72 is closed may be different. For example, the fuel discharge section 72 may be closed after the hydrogen fuel supply section 55 is closed.

As described above with reference to FIG. 7, when the hydrogen fuel mode is transferred to the liquid fuel mode, the gas present in the hydrogen fuel supply pipe 10X is Hydrogen fuel is supplied to the combustion chamber 61 until the (hydrogen) pressure becomes less than the threshold value TH. Therefore, hydrogen fuel can be consumed without waste, and the amount of hydrogen fuel discharged from the hydrogen fuel supply pipe 10X through the discharge pipe 73 can be reduced.

The embodiments and examples of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit thereof. Further, the plurality of components disclosed in the above embodiments can be modified as appropriate. For example, some of the components shown in one embodiment may be added to the components of another embodiment, or some of the components shown in one embodiment may be configured. Elements may be deleted from the embodiment.

In addition, the drawings mainly schematically show each component in order to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings are Actual results may differ due to circumstances. Further, the configuration of each component shown in the above embodiment is an example, and is not particularly limited, and it goes without saying that various changes can be made without substantially departing from the effects of the present invention. .

(1) The engine system 100 described with reference to FIG. 1 does not need to have a liquid fuel mode. In this case, engine system 100 does not have liquid fuel supply 56 and only has a hydrogen fuel mode. In this case, when the engine 1 is stopped from the hydrogen fuel mode, the cooling mode is executed by an electric motor such as a starter motor or by inertia instead of the liquid fuel supply section 56 in FIG. In other respects, the residual hydrogen discharge control is the same as the residual hydrogen discharge control shown in FIGS. 4 and 5.

(2) The engine system 100 described with reference to FIG. 1 may have a mixed combustion mode. The mixed combustion mode is a mode in which both gaseous fuel and liquid fuel are combusted substantially simultaneously to cause the engine 1 to generate power. In FIG. 1, the mixed combustion mode is a mode in which both hydrogen fuel and liquid fuel are combusted substantially simultaneously to cause the engine 1 to generate power. Engine system 100 may have all of the mixed combustion mode, hydrogen fuel mode, and liquid fuel mode, or may have any two modes among the mixed combustion mode, hydrogen fuel mode, and liquid fuel mode. You may do so. Further, engine system 100 may have only a co-combustion mode.

For example, when stopping the engine 1 from the mixed combustion mode, the control unit 211 supplies air at a pressure higher than atmospheric pressure (or an inert gas such as nitrogen) while the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. ) is introduced into the hydrogen fuel supply pipe 10. In addition, when stopping the engine 1 from the mixed combustion mode, the control unit 211 controls the fuel discharge so that hydrogen fuel is discharged from the hydrogen fuel supply pipe 10 in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. 72. As a result, it is possible to effectively suppress hydrogen fuel from remaining in the hydrogen fuel supply pipe 10 after the engine 1 is stopped from the mixed combustion mode. In other respects, the residual hydrogen discharge control is the same as the residual hydrogen discharge control shown in FIGS. 4 and 5.

For example, when transitioning from the co-combustion mode to the liquid fuel mode, the control unit 211 supplies air at a pressure higher than atmospheric pressure (or an inert gas such as nitrogen) while the supply of hydrogen fuel to the hydrogen fuel supply pipe 10 The hydrogen fuel supply unit 55 is controlled so as to introduce gas) into the hydrogen fuel supply pipe 10. In addition, when shifting from the mixed combustion mode to the liquid fuel mode, the control unit 211 controls the fuel so that the hydrogen fuel is discharged from the hydrogen fuel supply pipe 10 in a state where the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X is cut off. Controls the discharge section 72. As a result, it is possible to effectively suppress hydrogen fuel from remaining in the hydrogen fuel supply pipe 10 after shifting from the co-combustion mode to the liquid fuel mode. In other respects, the residual hydrogen discharge control is the same as the residual hydrogen discharge control shown in FIGS. 6 and 7.

The case where the mixed combustion mode shifts to the liquid fuel mode refers to the case where the liquid fuel mode shift conditions are satisfied. The liquid fuel mode transition conditions indicate conditions for transitioning the operating mode of the engine 1 from the mixed combustion mode to the liquid fuel mode. The liquid fuel mode transition condition is, for example, that the control unit 211 has received a transition instruction from the operation control device 23 to transition from the co-combustion mode to the liquid fuel mode. Alternatively, the liquid fuel mode transition condition may be, for example, when the control unit 211 determines to transition the operating mode from the mixed combustion mode to the liquid fuel mode based on the state of the engine 1 by executing calculations according to a computer program. That's what I did. In other respects, the residual hydrogen discharge control is the same as the residual hydrogen discharge control shown in FIGS. 6 and 7.

(3) In the engine system 100 described with reference to FIG. 1, the fuel discharge section 72 discharged the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X through the discharge pipe 73 into the engine room. However, the discharge pipe 73 may be connected to a tank (not shown). In this case, the fuel discharge section 72 discharges the hydrogen fuel remaining in the hydrogen fuel supply pipe 10X to the tank through the discharge pipe 73. As a result, hydrogen fuel is stored in the tank.

In particular, when ammonia is used as the gaseous fuel, it is effective for the fuel discharge section 72 to discharge the ammonia fuel remaining in the gaseous fuel supply pipe 10X to the tank through the discharge pipe 73. This is because ammonia is toxic. Note that even when natural gas (vaporized liquefied natural gas) is used as the gaseous fuel, the fuel discharge section 72 discharges the natural gas fuel remaining in the gaseous fuel supply pipe 10X to the tank through the discharge pipe 73. good.

(4) During period T2 in FIGS. 4 and 6, the hydrogen fuel supply section 55 introduced air into the hydrogen fuel supply pipe 10X by repeating opening and closing. However, as long as air can be introduced into the hydrogen fuel supply pipe 10X, the operation of the hydrogen fuel supply section 55 is not particularly limited.

For example, when discharging hydrogen fuel remaining in the hydrogen fuel supply pipe 10X, the fuel flow rate adjustment unit 71 cuts off the supply of hydrogen fuel to the hydrogen fuel supply pipe 10X, and then continues to open the hydrogen fuel flow path. As a result, the hydrogen fuel supply section 55 supplies air (or an inert gas such as nitrogen) at a pressure higher than atmospheric pressure to the hydrogen fuel supply pipe 10X in a state where the fuel flow rate adjustment section 71 has cut off the supply of hydrogen fuel. Introduce. Specifically, for example, during the period T2 in FIGS. 4 and 6, the hydrogen fuel supply section 55 continuously opens the hydrogen fuel flow path 555 (see FIG. 2), thereby increasing the pressure higher than atmospheric pressure. of air is introduced into the hydrogen fuel supply pipe 10X. That is, during period T2 in FIGS. 4 and 6, the hydrogen fuel supply section 55 maintains the open state.

(5) When shifting from liquid fuel mode to hydrogen fuel mode or mixed combustion mode, it is not necessary to perform residual hydrogen discharge control. This is because in the hydrogen fuel mode and the mixed combustion mode, hydrogen fuel is always consumed, so no hydrogen fuel remains in the hydrogen fuel supply pipe 10X.

The present invention relates to an engine system and has industrial applicability.

1 Engine 9 Pressure detection section 10X Hydrogen fuel supply pipe (gaseous fuel supply pipe)
11 Supercharger 55 Hydrogen fuel supply section (gaseous fuel supply section)
56 Liquid fuel supply section 71 Fuel flow rate adjustment section 72 Fuel discharge section 100 Engine system 211 Control section

Claims (11)

an engine that generates power by burning at least gaseous fuel;
a gaseous fuel supply pipe that supplies the gaseous fuel to the engine;
a fuel flow rate adjustment unit capable of cutting off the supply of the gaseous fuel to the gaseous fuel supply pipe;
Fuel for discharging the gaseous fuel remaining in the gaseous fuel supply pipe to the outside of the gaseous fuel supply pipe using gas at a pressure higher than atmospheric pressure when the fuel flow rate adjustment unit cuts off the supply of the gaseous fuel. Equipped with a discharge section and
The engine includes a gaseous fuel supply unit that supplies the gaseous fuel to the inside of the engine,
When burning the gaseous fuel, the gaseous fuel supply unit supplies the gaseous fuel supplied from the gaseous fuel supply pipe to the inside of the engine by opening the flow path of the gaseous fuel,
When discharging the gaseous fuel remaining in the gaseous fuel supply pipe, the gaseous fuel supply section opens the flow path of the gaseous fuel to adjust the fuel flow rate of the gas at a pressure higher than atmospheric pressure. introducing the gaseous fuel into the gaseous fuel supply pipe in a state where the gaseous fuel is cut off from the supply of the gaseous fuel,
The fuel discharge section is configured to remove the gaseous fuel remaining in the gaseous fuel supply pipe by the gas introduced into the gaseous fuel supply pipe in a state in which the fuel flow rate adjustment section cuts off the supply of the gaseous fuel. An engine system that discharges fuel to the outside of the supply pipe . The fuel discharge unit is configured to open the gaseous fuel supply pipe after the fuel flow rate adjustment unit shuts off the supply of the gaseous fuel, thereby reducing the gaseous fuel remaining in the gaseous fuel supply pipe to a level below atmospheric pressure. The engine system according to claim 1, wherein the gas at a high pressure is discharged to the outside of the gaseous fuel supply pipe. further comprising a supercharger that supplies air at a pressure higher than atmospheric pressure to the inside of the engine,
According to claim 1 or 2, the gas introduced into the gaseous fuel supply pipe when discharging the gaseous fuel remaining in the gaseous fuel supply pipe is the air supplied by the supercharger. Engine system as described. When burning the gaseous fuel, the gaseous fuel supply unit supplies the gaseous fuel to the inside of the engine by repeatedly opening and closing the flow path of the gaseous fuel,
When discharging the gaseous fuel remaining in the gaseous fuel supply pipe, the fuel flow rate adjustment section continues to repeat the operation of opening and closing the gaseous fuel flow path from before cutting off the supply of the gaseous fuel. The gaseous fuel supply section introduces the gas at a pressure higher than atmospheric pressure into the gaseous fuel supply pipe in a state where the fuel flow rate adjustment section cuts off the supply of the gaseous fuel, or
When discharging the gaseous fuel remaining in the gaseous fuel supply pipe, after the fuel flow rate adjustment section cuts off the supply of the gaseous fuel, the flow path of the gaseous fuel is continuously opened, so that the gaseous fuel is discharged. Any one of claims 1 to 3, wherein the supply unit introduces the gas at a pressure higher than atmospheric pressure into the gaseous fuel supply pipe in a state where the fuel flow rate adjustment unit cuts off the supply of the gaseous fuel. The engine system according to item 1 . further comprising a control unit that controls the engine,
The engine has at least one mode of a gas fuel mode and a mixed combustion mode,
The gaseous fuel mode is a mode in which the gaseous fuel is combusted to generate power for the engine,
The mixed combustion mode is a mode in which both the gaseous fuel and the liquid fuel are combusted substantially simultaneously to generate power for the engine,
When stopping the engine from the gaseous fuel mode or the mixed combustion mode, the control unit controls the gaseous fuel supply unit to introduce the gas at a pressure higher than atmospheric pressure into the gaseous fuel supply pipe, and The engine system according to any one of claims 1 to 4 , wherein the fuel discharge section is controlled to discharge the gaseous fuel from the gaseous fuel supply pipe. further comprising a liquid fuel supply section that supplies the liquid fuel to the inside of the engine,
The control unit controls the supply of the liquid fuel by the liquid fuel supply unit so that the engine maintains a constant rotation speed after the fuel flow rate adjustment unit cuts off the supply of the gaseous fuel. The engine system according to item 5 . further comprising a control unit that controls the engine,
The engine has at least one mode of a gas fuel mode and a mixed combustion mode, and a liquid fuel mode,
The gaseous fuel mode is a mode in which the gaseous fuel is combusted to generate power for the engine,
The liquid fuel mode is a mode in which the engine generates power by burning liquid fuel,
The mixed combustion mode is a mode in which both the gaseous fuel and the liquid fuel are combusted substantially simultaneously to generate power for the engine,
When transitioning from the gaseous fuel mode or the mixed combustion mode to the liquid fuel mode, the control unit controls the gaseous fuel supply unit to introduce the gas at a pressure higher than atmospheric pressure into the gaseous fuel supply pipe. The engine system according to any one of claims 1 to 4 , wherein the fuel discharge section is controlled to discharge the gaseous fuel from the gaseous fuel supply pipe. further comprising a liquid fuel supply section that supplies the liquid fuel to the inside of the engine,
The control unit controls the supply of the liquid fuel by the liquid fuel supply unit so that the rotational speed of the engine is maintained constant before and after the fuel flow rate adjustment unit cuts off the supply of the gaseous fuel. 8. The engine system of claim 7 , wherein the engine system controls: a pressure detection unit that detects the pressure of gas present in the gaseous fuel supply pipe;
further comprising a control section that controls the fuel discharge section,
If the pressure of the gas present in the gaseous fuel supply pipe becomes less than a threshold value after the fuel flow rate adjustment unit shuts off the supply of the gaseous fuel, the control unit controls the flow rate from the gaseous fuel supply pipe to the gaseous fuel supply pipe. The engine system according to any one of claims 1 to 4 , wherein the fuel discharge section is controlled to start discharging gaseous fuel. further comprising a control unit that controls the gaseous fuel supply unit,
The control unit controls the gaseous fuel supply unit so that the gaseous fuel supply unit closes the flow path of the gaseous fuel after a predetermined time has elapsed since the fuel discharge unit started discharging the gaseous fuel. The engine system according to any one of claims 1 to 4 , which controls the engine system. The engine system according to any one of claims 1 to 10 , wherein the gaseous fuel is hydrogen, ammonia, or natural gas.

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