JP2021067187A - Engine system - Google Patents

Abstract

To effectively improve a fuel economy performance.SOLUTION: An engine system comprises: an engine 10; a cooling water circuit 30 which has circulation flow passages 31, 32 and 33 circulating cooling water, a carburetor 24, a bypass flow passage 34 allowing the cooling water to bypass the carburetor 24 and a valve 36 controlling a flow of the cooling water through the flow passages; a fuel supply device 20 which has a gas tank 21 storing a gas in a liquid state, fuel supply pipes 22 and 23 connecting the gas tank 21 and the carburetor 24, and a buffer tank 26 storing the gas vaporized in the carburetor 24; a residual quantity sensor 84 which acquires a residual quantity of the gas in the buffer tank; a vaporization determination section 110 which determines whether or not the gas requires enhanced vaporization on the basis of the residual quantity; and a valve control section 120 which controls an operation of the valve 36 so as to allow the cooling water to flow through the carburetor 24 when the enhanced vaporization is determined to be required or controls the operation of the valve 36 so as to allow the cooling water to flow through the bypass flow passage 34 when the enhanced vaporization is determined not to be required.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to engine systems, and in particular to gas engine technology using natural gas as fuel.

For example, Patent Documents 1 and 2 disclose techniques for gas engines using natural gas as fuel.

JP-A-2019-094805 JP-A-2017-140921

In recent years, LNG vehicles equipped with a gas engine that uses LNG (Liquefied Natural Gas) as fuel have become widespread. Since LNG has a higher energy density per unit volume than CNG (compressed natural gas), it has an advantage that the cruising range of the vehicle per filling can be significantly extended.

In the above-mentioned LNG vehicle, the LNG stored in a liquid state in the tank is configured to be vaporized by heat exchange with the engine cooling water and then supplied to the engine. However, at the time of starting the engine, there is a problem that the temperature rise of the engine cooling water is hindered by the cold heat of LNG and the decrease in the viscosity of the engine oil is suppressed, which leads to an increase in friction loss. Further, the cold heat of LNG is radiated to the atmosphere as it is, and there is a problem that the cold heat cannot be effectively utilized. Therefore, it can be said that there is room for improvement in further improvement of fuel efficiency.

The technique of the present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to effectively improve fuel efficiency in a gas engine.

The technique of the present disclosure includes an engine using gas as fuel, a circulation flow path for circulating the cooling water of the engine, a vaporizer provided in the circulation flow path, and a vaporizer for cooling water circulating in the circulation flow path. A cooling water circuit including a bypass flow path that detours from the above, a valve that controls the cooling water flow path to the vaporizer or the bypass flow path, a gas tank that stores gas as fuel for the engine in a liquid state, and the gas tank. A fuel supply pipe connecting the vaporizer and the vaporizer, a fuel supply device including a buffer tank capable of storing the gas vaporized by the vaporizer and supplying the stored gas to the engine, and gas in the buffer tank. The remaining amount acquisition means for acquiring the remaining amount of the above, the vaporization determining means for determining whether or not it is necessary to promote the vaporization of the gas in the vaporizer based on the acquired remaining amount, and the vaporization determining means for promoting the vaporization. When it is determined that the vaporization is necessary, the operation of the valve is controlled to use the flow path of the cooling water as the vaporizer, and when it is determined by the vaporization determination means that the promotion of vaporization is unnecessary, the operation of the valve is controlled. A valve control means having the cooling water flow path as the bypass flow path is provided.

Further, a thermoacoustic engine including a loop pipe and a prime mover provided in the loop pipe is further provided, the prime mover includes a heat storage device, a cooler, and a heater, and the cooler includes the fuel supply pipe. It is connected, low-temperature gas is supplied from the gas tank via the fuel supply pipe, the circulation flow path is connected to the heater, and high-temperature cooling water flowing through the circulation flow path is supplied. Is preferable.

Further, it is preferable to further include a generator that drives power generation using the acoustic energy of the thermoacoustic engine.

Further, the outside air temperature acquisition means for acquiring the outside air temperature is further provided, and the vaporization determination means is used when the acquired remaining amount is less than a predetermined remaining amount threshold value and when the acquired remaining amount is the remaining amount threshold value. Even if it is the above, when the acquired outside air temperature is equal to or less than a predetermined threshold temperature, it is determined that promotion of gas vaporization is necessary, and the acquired remaining amount is equal to or more than the remaining amount threshold and is acquired. When the outside air temperature exceeds the threshold temperature, it is preferable to determine that promotion of gas vaporization is unnecessary.

According to the technique of the present disclosure, fuel efficiency can be effectively improved in a gas engine.

It is a schematic overall block diagram which shows the engine system which concerns on this embodiment. It is a schematic diagram explaining the flow path control of the engine cooling water by the flow rate adjustment valve in the engine system which concerns on this embodiment. It is a schematic functional block diagram which shows the control device which concerns on this embodiment, and the related peripheral configuration. It is a flowchart explaining the flow of the process of the cooling water flow path control which concerns on this embodiment.

Hereinafter, the engine system according to the present embodiment will be described based on the attached drawings. The same parts have the same reference numerals, and their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing an engine system according to the present embodiment.

The vehicle 1 is equipped with an engine 10 as a driving force source. The engine 10 is a gas engine that uses natural gas (for example, LNG) as fuel. Hereinafter, the fuel of the engine 10 will be described as LNG, but the engine 10 may use a natural gas other than LNG as a fuel as long as it is vaporized from a liquid and supplied.

The engine 10 has an engine main body mainly composed of a cylinder head, a cylinder block CB, and the like. A plurality of cylinders C are provided in the cylinder block CB, and a piston (not shown) is housed in each cylinder C so as to be reciprocating. The piston is connected to the crankshaft 11 via a connecting rod, a crankarm, or the like (not shown), and the reciprocating motion of the piston is converted into a rotary motion and transmitted to the crankshaft 11. Further, the cylinder head is provided with an injector I that injects LNG (gas state) into each cylinder C.

The engine 10 is not limited to the in-line multi-cylinder engine shown in the illustrated example, and may be a V-type engine, a horizontally opposed engine, or the like. Further, the engine 10 is not limited to a multi-cylinder engine, and may be a single-cylinder engine. Further, the engine 10 may be either a premixed type or a direct injection type.

The crankshaft 11 is provided with a drive pulley 12. An alternator 15 is connected to the drive pulley 12 via a belt 13 and a driven pulley 14. The electric power generated by the alternator 15 is stored in the vehicle-mounted battery 16 according to the SOC, or is supplied to an electrical component (not shown).

The fuel supply device 20 includes an LNG tank 21 (the gas tank of the present disclosure), an upstream supply pipe 22 (the fuel supply pipe of the present disclosure), an intermediate supply pipe 23 (the fuel supply pipe of the present disclosure), a vaporizer 24, and the like. It includes a downstream supply pipe 25, a buffer tank 26, and a branch pipe 27.

The LNG tank 21 is a low temperature tank capable of storing LNG in a low temperature state (for example, about −160 ° C. or lower). LNG is stored in the LNG tank 21 in a liquid state. The LNG tank 21 is connected to the cooler 54 of the thermoacoustic engine 50, which will be described later, via the upstream supply pipe 22. The upstream supply pipe 22 is preferably formed to have a short length so that the cooler 54 and the LNG tank 21 are brought close to each other.

The vaporizer 24 is connected to the cooler 54 via an intermediate supply pipe 23. The vaporizer 24 vaporizes LNG supplied in a liquid state from the LNG tank 21 via the upstream supply pipe 22, the cooler 54, and the intermediate supply pipe 23 by exchanging heat with the engine cooling water. Let me.

The buffer tank 26 is a fuel accumulator and is connected to the vaporizer 24 via a downstream supply pipe 25. The buffer tank 26 temporarily stores the LNG vaporized by the vaporizer 24 in a gaseous state. The buffer tank 26 is connected to each injector I via a distribution pipe 27. The amount of fuel supplied from the buffer tank 26 to each injector I is controlled based on a command transmitted from the control device 100 according to the operating state of the engine 10.

The engine 10 is provided with a first cooling water circuit 30 and a second cooling water circuit 40.

The second cooling water circuit 40 circulates engine cooling water between a water jacket (not shown) provided in the cylinder block CB and a radiator 41. The radiator 41 cools the engine cooling water by exchanging heat with the outside air. A second cooling water supply pipe 42 branching from the water jacket is connected to the radiator 41. Further, a second cooling water return pipe 43 that joins the water jacket is connected to the radiator 41.

The second cooling water return pipe 43 is provided with a mechanical second cooling water pump 44 driven by the power of the engine 10. The second cooling water pump 44 is not limited to the mechanical pump, and may be an electric pump. Further, the second cooling water pump 44 may be provided in the second cooling water supply pipe 42.

The first cooling water circuit 30 (cooling water circuit of the present disclosure) includes a first upstream cooling water supply pipe 31 (circulation flow path of the present disclosure) and a first downstream cooling water supply pipe 32 (circulation flow path of the present disclosure). A first cooling water return pipe 33 (circulation flow path of the present disclosure), a bypass pipe 34 (bypass flow path of the present disclosure), a first cooling water pump 35, and a flow rate adjusting valve 36 (valve of the present disclosure). And have.

The first upstream cooling water supply pipe 31 branches from the water jacket of the cylinder block CB and is connected to the heater 55 of the thermoacoustic engine 50 described later. The first upstream cooling water supply pipe 31 is provided with a heater 39 for an vehicle interior air conditioner. By providing the heater 39 on the upstream side of the vaporizer 24, the deterioration of the performance of the heater 39 can be effectively suppressed. The heater 39 may be provided at another portion as long as it is on the upstream side of the vaporizer 24 (flow rate adjusting valve 36) of the first cooling water circuit 30. Further, the heater 39 may be provided in another cooling water circuit separate from the first cooling water circuit 30 and the second cooling water circuit 40.

The first downstream cooling water supply pipe 32 connects the heater 55 of the thermoacoustic engine 50 and the vaporizer 24. The first cooling water return pipe 33 connects the vaporizer 24 and the water jacket of the cylinder block CB. The first downstream cooling water supply pipe 32 and the first cooling water return pipe 33 bypass the engine cooling water from the vaporizer 24 and circulate the engine cooling water from the first downstream cooling water supply pipe 32 to the first cooling water return pipe 33. They are connected to each other by a bypass pipe 34.

A flow rate adjusting valve 36 is provided at a branch portion of the first downstream cooling water supply pipe 32 from the bypass pipe 34. The opening degree of the flow rate adjusting valve 36 is controlled in response to a command from the control device 100.

Specifically, as shown in FIG. 2, the flow rate adjusting valve 36 is in the first state (FIG. 2 (FIG. 2)) in which the flow path of the bypass pipe 34 is blocked and the engine cooling water is circulated to the first downstream cooling water supply pipe 32. A)) and the second state (see FIG. 2B) in which a small amount of cooling water is circulated through the first downstream cooling water supply pipe 32 while a large amount of engine cooling water is circulated through the bypass pipe 34. It is configured to be possible. In this way, even when the engine cooling water is circulated to the bypass pipe 34, a part of the engine cooling water is circulated to the first downstream cooling water supply pipe 32 and supplied to the carburetor 24, so that the inside of the carburetor 24 is supplied. It is possible to effectively prevent the engine cooling water from freezing completely. Here, the opening degree of the flow rate adjusting valve 36 when a part of the cooling water is circulated to the first downstream cooling water supply pipe 32 is not limited to a fixed value, and is limited to the fuel temperature of the LNG, the outside air temperature, and the like. The lower the temperature, the more the amount of cooling water to be circulated in the first downstream cooling water supply pipe 32 may be secured.

Returning to FIG. 1, the first cooling water pump 35 is, for example, an electric pump that circulates engine cooling water in the first cooling water circuit 30. In the illustrated example, the first cooling water pump 35 is provided in the first upstream cooling water supply pipe 31, but may be provided in another part of the first cooling water circuit 30. Further, the first cooling water pump 35 is not limited to the electric pump, and may be a mechanical pump driven by the power of the engine 10.

The thermoacoustic engine 50 is an external combustion engine driven by using the cold heat of LNG, and includes a loop pipe 51 and a resonance pipe 56. The external combustion engine is not limited to the thermoacoustic engine 50, and a Stirling engine or the like can also be used.

The loop pipe 51 is provided with a heat storage device 53, a cooler 54, and a heater 55 that constitute the prime mover 52. Further, the thermoacoustic engine 50 is provided with a generator (linear generator in the illustrated example) 58. The generator 58 may be installed at any location on the resonance tube 56 or at any location on the loop tube 51. The cooler 54 is supplied with low-temperature LNG from the LNG tank 21, and the heater 55 is supplied with high-temperature engine cooling water flowing through the first cooling water circuit 30.

In the thermoacoustic engine 50, when a temperature gradient is generated in the heat storage device 53 by the low temperature LNG supplied to the cooler 54 and the high temperature cooling water supplied to the heater 55, self-excited vibration, which is a sound wave, is excited. The generator 58 is configured to generate and drive by the vibration energy (acoustic energy) of the sound waves. The electric power generated by the generator 58 is stored in the vehicle-mounted battery 16 according to the SOC, or is supplied to an electrical component (not shown).

In this way, the load on the alternator 15 can be effectively reduced by driving the generator 58 to generate electricity by the thermoacoustic engine 50 using the cold heat of LNG. As a result, the fuel efficiency of the engine 10 can be reliably improved. The generator 58 is not limited to the linear generator shown in the illustrated example, and may be a turbine-type generator driven by a turbine arranged in the loop pipe 51 or the resonance pipe 56. As the turbine shape, for example, an impulse turbine used for wave power generation or the like is desirable. Further, the driven device driven by the thermoacoustic engine 50 is not limited to the generator 58, and may be a compressor or the like that supplies pressurized air to an air tank (not shown).

The vehicle 1 is equipped with a GPS (Global Positioning System) receiver 70. The GPS receiver 70 acquires position information indicating the current position of the vehicle 1 in real time at predetermined intervals. The position information of the vehicle 1 acquired by the GPS receiver 70 is transmitted to the control device 100.

Further, the vehicle 1 is provided with various sensors. The engine speed sensor 80 detects the engine speed Ne from the crank shuff 11. The accelerator opening sensor 81 detects the accelerator opening AC (required torque) according to the amount of depression of the accelerator pedal (not shown). The atmospheric temperature sensor 82 (the atmospheric temperature acquiring means) detects the atmospheric temperature TA. The fuel temperature sensor 83 detects _{the LNG temperature TLNG in the LNG tank 20.} The remaining amount sensor 84 (remaining amount acquisition means) is, for example, a pressure sensor, and detects _{NG remaining amount A NG in the buffer tank 26.} The detection signals of these sensors 80 to 84 are transmitted to the electrically connected control device 100.

[Control device]
FIG. 3 is a schematic functional block diagram showing the control device 100 according to the present embodiment and related peripheral configurations.

The control device 100 is, for example, a device that performs calculations such as a computer, and is a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, and an output port connected to each other by a bus or the like. And so on, and execute the program.

Further, the control device 100 functions as a device including a vaporization promotion determination unit 110 (vaporization determination means) and a cooling water flow path control unit 120 (valve control means) by executing the program. Each of these functional elements will be described as being included in the control device 100, which is integrated hardware in the present embodiment, but any part of these may be provided in separate hardware.

The vaporization promotion determination unit 110 determines whether or not it is necessary to promote the vaporization of LNG based on _{the NG remaining amount A NG} in the buffer tank 26 transmitted from the remaining amount sensor 84.

Specifically, the vaporization promotion determination unit 110 does _{not need to promote the vaporization of LNG when the NG remaining amount A NG} transmitted from the remaining amount sensor 84 is equal to or higher than a predetermined remaining amount threshold value (for example, 80%). judge. Further, in the vaporization promotion determination unit 110, _{even if the NG remaining amount A NG} transmitted from the remaining amount sensor 84 is equal to or higher than the predetermined remaining amount threshold value, the atmospheric temperature TA transmitted from the atmospheric temperature sensor 82 corresponds to winter or the like. When the temperature is below a predetermined threshold temperature (for example, −10 ° C.), it is determined that the vaporization of LNG needs to be promoted. Further, in the vaporization promotion determination unit 110, the NG remaining amount A _NG transmitted from the remaining amount sensor 84 is equal to or higher than the predetermined remaining amount threshold value, and the atmospheric temperature TA transmitted from the atmospheric temperature sensor 82 sets the predetermined threshold temperature. If the load on the engine 10 is expected to increase even if it exceeds the limit, it is determined that it is necessary to promote the vaporization of LNG.

Whether or not the load increase of the engine 10 is predicted depends on the operation of the engine 10 according to the engine speed Ne transmitted from the engine speed sensor 80, the accelerator opening AC transmitted from the accelerator opening sensor 81, and the like. It may be predicted based on the state. Alternatively, it is predicted by determining whether or not the road surface condition on which the vehicle 1 travels is an uphill road or the like based on the current position information of the vehicle 1 acquired by the GPS receiver 70, the information road map information, and the like. You may. Alternatively, the prediction may be made based on whether or not a large number of uphill roads are included in the traveling route set by the car navigation system (not shown) mounted on the vehicle 1. The determination result by the vaporization promotion determination unit 110 is transmitted to the cooling water flow path control unit 120.

The cooling water flow path control unit 120 controls the operation of the flow rate adjusting valve 36 according to the determination result of the vaporization promotion determination unit 110 to switch the flow path of the engine cooling water to the vaporizer 24 or the bypass pipe 34. To carry out.

Specifically, the cooling water flow path control unit 120 controls the flow rate adjusting valve 36 to the first state (see FIG. 2A) when the vaporization promotion determination unit 110 determines that the vaporization promotion of LNG is necessary. That is, the engine cooling water is supplied to the vaporizer 24 by blocking the flow path of the bypass pipe 34 and opening the flow path of the first downstream cooling water supply pipe 32. As a result, the vaporization of LNG is effectively promoted by heat exchange with the engine cooling water, and it becomes possible to keep the _{remaining amount of NG A NG in the buffer tank 26 at a high level.}

On the other hand, the cooling water flow path control unit 120 controls the flow rate adjusting valve 36 to the second state (see FIG. 2B) when the vaporization promotion determination unit 110 determines that the promotion of vaporization of LNG is unnecessary. That is, most of the engine cooling water is supplied to the bypass pipe 34 by opening the flow path of the bypass pipe 34 and slightly opening the flow path of the first downstream cooling water supply pipe 32.

This makes it possible to effectively prevent the temperature of the engine cooling water from dropping due to heat exchange with the LNG, and further to prevent the temperature of the engine oil from dropping, and the friction loss energy due to the increase in the viscosity of the engine oil. It is also possible to suppress the increase in. Further, by suppressing the increase in friction loss energy, it is possible to surely improve the fuel efficiency performance of the engine 10. Further, by suppressing the temperature drop of the engine cooling water, the temperature of the heater 39 can be raised, and the heating performance of the air conditioner can be improved.

Next, the flow of the cooling water flow path control process according to the present embodiment will be described with reference to FIG. This routine is preferably started at the same time as the engine 10 is started (ignition switch ON). Further, it is assumed that the first cooling water pump 35 also starts driving at the same time as the engine 10 is started.

_{In step S100, it is determined whether or not the NG remaining amount A NG} transmitted from the remaining amount sensor 84 is equal to or greater than the predetermined remaining amount threshold value. When the NG remaining amount A _NG is not equal to or more than the remaining amount threshold value (No), that is, when the NG remaining amount A _NG is less than the remaining amount threshold value, it is determined that the vaporization of LNG needs to be promoted, and this control proceeds to step S160. On the other hand, when the NG remaining amount A _NG is equal to or higher than the remaining amount threshold value (Yes), this control proceeds to step S110.

In step S160, the flow rate adjusting valve 36 is controlled to the first state (see FIG. 2A), and the flow path of the engine cooling water is the vaporizer 24. As a result, the vaporization of LNG is promoted by heat exchange with the engine cooling water.

_{Next, in step S170, it is determined whether or not the NG remaining amount A NG} transmitted from the remaining amount sensor 84 has reached a predetermined remaining amount threshold value. NG remaining amount A When _NG does not reach the predetermined remaining amount threshold value (No), this control is returned to the process of step S160. On the other hand, when the NG remaining amount A _NG reaches a predetermined remaining amount threshold value (Yes), this control proceeds to step S180. The process of step S180 will be described later.

When the process proceeds from step S100 to step S110, it is determined whether or not the atmospheric temperature TA transmitted from the atmospheric temperature sensor 82 is equal to or lower than a predetermined threshold temperature. When the atmospheric temperature TA is equal to or lower than the predetermined threshold temperature, this control proceeds to step S160 described above. That is, the vaporization of LNG is promoted by heat exchange with the engine cooling water. On the other hand, when the atmospheric temperature TA is not equal to or lower than the predetermined threshold temperature (No), that is, when the atmospheric temperature TA exceeds the predetermined threshold temperature, this control proceeds to the determination process in step S120.

In step S120, it is determined whether or not an increase in the load of the engine 10 is predicted. When an increase in the load of the engine 10 is predicted (Yes), this control proceeds to step S160 described above, and promotes vaporization of LNG by heat exchange with the engine cooling water. On the other hand, when the load increase of the engine 10 is not predicted (No), this control proceeds to step S130.

In step S130, the flow rate adjusting valve 36 is controlled to the second state (see FIG. 2B), and the flow path of the engine cooling water is set to the bypass pipe 34. As a result, the heat exchange between the engine cooling water and the LNG is stopped (or reduced), and the temperature drop of the engine cooling water is suppressed.

In step S180, it is determined whether or not the engine 10 has stopped (ignition switch OFF). If the engine 10 is not stopped (No), this control is returned to the determination process in step S100. On the other hand, when the engine 10 is stopped (Yes), this control proceeds to step S190, stops driving the first cooling water pump 35, and then returns.

According to the present embodiment described in detail above, _{it is determined whether or not it is necessary to promote the vaporization of LNG based on the NG remaining amount A NG} of the buffer tank 26, and if it is necessary to promote the vaporization of LNG, the engine cooling water is used. Is configured to replenish the buffer tank 26 with LNG by supplying the vaporizer 24. As a result, the remaining amount of NG A _NG in the buffer tank 26 can be surely kept at a high level.

Further, when it is not necessary to promote the vaporization of LNG, the temperature drop of the engine cooling water can be effectively suppressed by supplying the engine cooling water to the bypass pipe 34 that bypasses the vaporizer 24. .. As a result, the increase in viscous resistance due to the temperature drop of the engine oil is suppressed, the increase in friction loss energy can be effectively suppressed, and the fuel efficiency performance of the engine 10 can be improved.

Further, the SOC of the in-vehicle battery 16 can be maintained at a high level by driving the generator 58 to generate electricity by the thermoacoustic engine 50 using the cold heat of LNG. As a result, the load on the alternator 15 can be effectively reduced, and the fuel efficiency of the engine 10 can be reliably improved.

[Other]
The present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, in the above embodiment, in the process of determining whether or not it is necessary to promote the vaporization of LNG, the process of determining whether or not the LNG temperature _TLNG in the LNG tank 20 acquired by the fuel temperature sensor 83 exceeds the threshold value. May be added further.

Further, although the fuel of the engine 10 has been described by taking LNG as an example, it can be widely applied to a gas engine using other natural gas as a fuel, which needs to be vaporized by heat exchange with the engine cooling water. Further, the above embodiment can be widely applied to other than vehicles.

10 Engine 20 Fuel supply device 21 LNG tank (gas tank)
22 Upstream supply pipe (fuel supply pipe)
23 Intermediate supply pipe (fuel supply pipe)
24 Vaporizer 25 Downstream supply pipe 26 Buffer tank 27 Branch pipe 30 First cooling water circuit 30 (cooling water circuit)
31 First upstream cooling water supply pipe (circulation flow path)
32 First downstream cooling water supply pipe (circulation flow path)
33 First cooling water return pipe (circulation flow path)
34 Bypass pipe (bypass flow path)
35 1st cooling water pump 36 Flow rate adjustment valve (valve)
50 Thermoacoustic engine 51 Loop tube 52 Motor 53 Heat storage device 54 Cooler 55 Heater 56 Resonator tube 58 Generator 82 Air temperature sensor (air temperature acquisition means)
84 Remaining amount sensor (remaining amount acquisition means)
100 Control device 110 Vaporization promotion determination unit (Vaporization determination means)
120 Cooling water flow path control unit

Claims (4)

A gas-fueled engine and
A circulation flow path for circulating the cooling water of the engine, a vaporizer provided in the circulation flow path, a bypass flow path for bypassing the cooling water circulating in the circulation flow path from the vaporizer, and a cooling water flow path. A cooling water circuit including a valve for controlling the vaporizer or the bypass flow path, and
A gas tank that stores gas as fuel for the engine in a liquid state, a fuel supply pipe that connects the gas tank and the vaporizer, stores the gas vaporized by the vaporizer, and supplies the stored gas to the engine. With a fuel supply system including a possible buffer tank,
A remaining amount acquisition means for acquiring the remaining amount of gas in the buffer tank, and
A vaporization determination means for determining whether or not it is necessary to promote the vaporization of gas in the vaporizer based on the acquired remaining amount.
When it is determined by the vaporization determining means that promotion of vaporization is necessary, the operation of the valve is controlled to use the flow path of the cooling water as the vaporizer, and when it is determined by the vaporization determining means that promotion of vaporization is unnecessary, the said An engine system comprising: a valve control means for controlling the operation of a valve and using the flow path of cooling water as the bypass flow path. Further equipped with a thermoacoustic engine including a loop tube and a prime mover provided in the loop tube.
The prime mover includes a heat storage device, a cooler, and a heater, and the fuel supply pipe is connected to the cooler, and low-temperature gas is supplied from the gas tank via the fuel supply pipe to heat the engine. The engine system according to claim 1, wherein the circulation flow path is connected to the vessel, and high-temperature cooling water flowing through the circulation flow path is supplied. The engine system according to claim 2, further comprising a generator that drives electricity using the acoustic energy of the thermoacoustic engine. Further equipped with an outside temperature acquisition means to acquire the outside temperature,
In the vaporization determination means, when the acquired remaining amount is less than the predetermined remaining amount threshold value, and even if the acquired remaining amount is equal to or more than the remaining amount threshold value, the acquired outside air temperature is predetermined. When it is determined that promotion of gas vaporization is necessary when the temperature is below the threshold temperature, and when the acquired remaining amount is equal to or more than the remaining amount threshold and the acquired outside air temperature exceeds the threshold temperature, the gas is obtained. The engine system according to any one of claims 1 to 3, wherein it is determined that the promotion of vaporization is unnecessary.

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