Fuel supply device

Abstract

To efficiently cool fuel that is liquefied gas in a supply process to an engine and supply the fuel in a liquid state without causing lowering of pressure of the fuel in the supply process.SOLUTION: Fuel stored in a fuel tank 12 is divided into fuel F1 to be sent by a first fuel supply system 40 and fuel F2 to be sent by a second fuel supply system 42 and is supplied to an intake flow passage 22 of an engine 10. The fuel F2 is sprayed into a chamber 54 of a cooler 52 by a sprayer 60 and is evaporated. The fuel F1 flows in a cooling pipe 58 extending in the chamber 54 and is cooled by using evaporative latent heat of the sprayed fuel F2. Division of a flow passage between the fuel F2 to be used for cooling and the fuel F1 to be cooled enables the fuel F1 to be supplied from the fuel tank 12 to a first injection valve 44 without changing the liquid state, and is injected from the first injection valve 44 by using pressure in the fuel tank 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel supply system for supplying a fuel, particularly a liquefied gas, to an engine. [Background technology]

[0002] In an engine that uses liquid fuel, if a portion of the fuel evaporates and becomes a gas-liquid mixture, the amount of fuel supplied to the cylinders of the engine may become unstable. In particular, when liquefied gas is used as the fuel, the fuel is likely to become a gas-liquid mixture.

[0003] In the patent document 1 listed below, an intermediate tank (19) is provided in the middle of a feed line (13) that sends fuel to a high-pressure pump (4) that increases the pressure of the fuel to be injected into the cylinders, and a part of the fuel is evaporated in the intermediate tank (19) and cooled using the latent heat of evaporation. By cooling the fuel, only liquid fuel is supplied to the high-pressure pump (4).

[0004] In the following Patent Document 2, fuel is cooled by a heat exchanger (2) including a sealed container (2-2) in which a heat transfer fluid (6) is stored and a fuel pipe (1B) penetrating the sealed container (2-2). A wick material (4) is attached to the outer surface of the fuel pipe (1B), and the heat transfer fluid (6) sucked up by the wick material (4) evaporates due to capillary action, and the fuel flowing through the fuel pipe (1B) is cooled by the latent heat of evaporation.

[0005] The reference symbols in parentheses above are used in Patent Documents 1 and 2, and are not related to the reference symbols used in the description of the embodiments of the present application. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-133597 A [Patent Document 2] JP 2003-35219 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned Patent Document 1, an intermediate tank that evaporates part of the fuel is placed in the feed line that transports the fuel, so the pressure of the fuel transported through the feed line drops.In the above-mentioned Patent Document 2, if the temperature of the heat transfer fluid in the sealed container and the temperature of the fuel flowing through the fuel pipe are close, the heat transfer fluid does not evaporate sufficiently, and the fuel cannot be cooled sufficiently.

[0008] The present invention aims to at least one of efficiently cooling liquefied gas fuel during the process of supplying it to an engine and supplying the fuel in a liquid state without causing a pressure drop during the supply process. [Means for solving the problem]

[0009] The fuel supply device according to the present invention is a fuel supply device that supplies liquefied gas fuel to an engine, and includes a first fuel supply system and a second fuel supply system that respectively supply fuel stored in a liquefied state in a fuel tank toward the intake air of the engine, and a cooler that cools the fuel supplied by the first fuel supply system by utilizing the latent heat of evaporation of the fuel supplied by the second fuel supply system. The first fuel supply system has a first injection valve that injects fuel in a liquid state into the intake air of the engine, and a first feed flow path that feeds fuel to the first injection valve. The second fuel supply system has a second injection valve that injects fuel in a gaseous state or a gas-liquid mixture state into the intake air of the engine, and a second feed flow path that feeds fuel to the second injection valve. The cooler has a chamber that forms a part of the second feed flow path and defines an evaporation space, a cooling pipe that forms a part of the first feed flow path and extends within the evaporation space, and a sprayer that atomizes the fuel flowing through the second feed flow path and supplies it to the evaporation space.

[0010] The fuel supplied to the evaporation space in the chamber evaporates, and the temperature of the evaporation space drops due to the latent heat of evaporation. This cools the cooling pipe extending through the evaporation space, which in turn cools the fuel flowing through the cooling pipe. As the temperature of the fuel supplied by the first fuel supply system drops, the first injector injects fuel in a liquid state.

[0011] In the above fuel supply device, the amount of fuel supplied to the engine may be adjusted by the fuel supplied by the first fuel supply system. It is easier to control the supply amount of fuel in a liquid state than fuel in a gas-liquid mixed state.

[0012] In the above fuel supply device, the second fuel supply system may have an evaporator provided downstream of the cooler, and the fuel that has not been evaporated by the cooler may be evaporated in the evaporator. If the fuel supplied by the second fuel supply system is in a gaseous state, it becomes easier to control the amount of fuel supplied by the second fuel supply system.

[0013] In the above fuel supply device, the second fuel supply system may have a reformer provided downstream of the evaporator, and the reformer may convert at least a part of the fuel into hydrogen. Hydrogen has good ignition properties and can improve the ignition properties of the fuel, which is a liquefied gas.

[0014] The above fuel supply device may include an auxiliary fuel supply system that supplies fuel having better ignition ability than the liquefied gas fuel as auxiliary fuel toward the intake air of the engine. When the liquefied gas fuel has poor ignition ability, the ignition ability can be improved.

[0015] In the above fuel supply device, the temperature of the fuel supplied by the first supply passage may be controlled by the amount of fuel supplied by the atomizer. The temperature of the fuel supplied by the first supply passage can be stabilized.

[0016] In the above fuel supply device, the liquefied gas as the fuel may be ammonia. Since ammonia does not contain carbon, no carbon dioxide is emitted. Effect of the Invention

[0017] By supplying the fuel in a mist form to the evaporation space, the temperature of the evaporation space can be efficiently lowered. By separating the fuel to be cooled and the fuel to be cooled from each other through separate supply lines, the fuel to be cooled can be injected in a liquid state while maintaining the pressure of the fuel to be cooled at the same pressure as that in the fuel tank. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram illustrating a schematic configuration of a fuel supply device according to an embodiment of the present invention; [Diagram 2] 11A to 11C are diagrams showing the state of fuel during the delivery process. [Diagram 3] FIG. 10 is a diagram showing a schematic configuration of another aspect of the fuel supply device of the present embodiment, in particular an aspect having an evaporator that evaporates liquid-state fuel that remains unevaporated in the cooler. [Figure 4] FIG. 11 is a diagram showing a schematic configuration of still another aspect of the fuel supply device of the present embodiment, in particular an aspect having a regulator for supplying evaporated fuel at a constant pressure. [Diagram 5] FIG. 13 is a diagram showing a schematic configuration of still another aspect of the fuel supply device of the present embodiment, in particular an aspect including a supply system for auxiliary fuel for ignition. [Figure 6] FIG. 13 is a diagram showing a schematic configuration of still another aspect of the fuel supply device of the present embodiment, in particular an aspect including a reformer that converts evaporated fuel into hydrogen. [Figure 7] FIG. 13 is a schematic diagram showing the configuration of yet another aspect of the fuel supply device of the present embodiment, in particular an aspect that includes a reformer that converts evaporated fuel into hydrogen and is capable of supplying the reformed hydrogen and the evaporated fuel separately. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of an engine 10, a fuel tank 12 storing liquefied gas as fuel, and a fuel supply device 14 that supplies fuel from the fuel tank 12 to the engine 10. The liquefied gas as fuel is, for example, ammonia, and the following description will be given of the case where the fuel is ammonia.

[0020] A cylinder 16 of the engine 10 is defined by a cylindrical inner wall surface of a cylinder block and a cylinder head disposed so as to close the top of the cylinder block. A piston 18 that reciprocates along the axial direction is disposed within the cylinder 16. The cylindrical inner wall surface of the cylinder block that defines the cylinder 16, the inner wall surface of the cylinder head, and the top surface of the piston 18 define a combustion chamber 20. Although the engine 10 is shown in FIG. 1 as having one cylinder 16, the engine may have a plurality of cylinders, such as four or six cylinders.

[0021] An intake passage 22 through which intake air flows toward the cylinder 16 and an exhaust passage 24 through which exhaust gas discharged from the cylinder 16 flows are connected to the cylinder 16. The intake passage 22 includes an intake port 26 formed in the cylinder head, and an end of the intake port 26 opens toward the combustion chamber 20. An intake valve 28 capable of opening and closing the opening of the intake port 26 is disposed in the cylinder head. The exhaust passage 24 includes an exhaust port 30 formed in the cylinder head, and an end of the exhaust port 30 opens toward the combustion chamber 20. An exhaust valve 32 capable of opening and closing the opening of the exhaust port 30 is disposed in the cylinder head. An exhaust purification device 34 is disposed in the exhaust passage 24. The exhaust purification device 34 purifies the exhaust gas using an oxidation-reduction catalyst that oxidizes unburned or incompletely burned fuel and simultaneously reduces nitrogen oxides. In order to simultaneously perform oxidation and reduction, the exhaust gas needs to have a stoichiometric composition, and for this purpose, an air excess ratio sensor 36 is disposed in the exhaust passage 24 upstream of the exhaust purification device 34. Based on the excess air ratio detected by the excess air ratio sensor 36, the amount of fuel supplied is adjusted so that the mixture composition in the cylinder 16 becomes stoichiometric. An ignition plug 38 is disposed at the top of the cylinder 16 for igniting the fuel in the combustion chamber 20.

[0022] Liquefied gas (ammonia in this embodiment) serving as fuel is stored in a liquid state in the fuel tank 12. The fuel is pumped out from the fuel tank 12 in a liquid state.

[0023] The fuel supply device 14 includes a first fuel supply system 40 that supplies fuel in a liquid state toward the intake air flowing through the intake passage 22, and a second fuel supply system 42 that supplies fuel in a gaseous state or a gas-liquid mixed state toward the intake air flowing through the intake passage 22.

[0024] The first fuel supply system 40 has a first injection valve 44 that injects fuel into the intake passage 22, particularly the intake port 26, and a first feed passage 46 that feeds fuel from the fuel tank 12 to the first injection valve 44. The first injection valve 44 injects fuel by utilizing the pressure in the fuel tank 12. In other words, the first feed passage 46 is not provided with a pressure boosting means such as a pump for increasing the pressure of the fuel, and the pressure in the fuel tank 12 directly acts on the first injection valve 44. In other words, the first injection valve 44 injects fuel by utilizing the pressure in the fuel tank 12. A fuel temperature sensor 47 for detecting the temperature of the fuel is disposed in the first feed passage 46 near the first injection valve 44.

[0025] The second fuel supply system 42 includes a second injector 48 that injects fuel into the intake passage 22 and a second delivery passage 50 that delivers fuel from the fuel tank 12 to the second injector 48. The second injector 48 may be positioned to inject fuel toward the intake port 26.

[0026] The fuel supply device 14 further includes a cooler 52 for cooling the fuel flowing through the first feed passage. The cooler 52 has a chamber 54 forming a part of the second feed passage 50 and a cooling pipe 58 forming a part of the first feed passage 46 and extending through a space 56 defined by the chamber 54. The cooler 52 further includes a sprayer 60 for spraying fuel into the space 56 in the chamber 54. The sprayer 60 forms a part of the second feed passage 50 and sprays fuel directly supplied from the fuel tank 12 or fuel supplied by branching off from the first feed passage 46 upstream of the cooling pipe 58 into the space 56 in the chamber 54. At least a part of the sprayed fuel evaporates in the space 56. This space 56 is hereinafter referred to as the evaporation space 56. The fuel (gas) evaporated in the evaporation space 56 and the fuel (liquid) not evaporated are sent to the second injector 48 by the second feed passage 50. The second injector 48 injects fuel using the pressure built up by the evaporation of the fuel.

[0027] As the fuel evaporates, the cooling pipe 58 in the evaporation space 56 is cooled by the latent heat of evaporation, and the fuel flowing through the cooling pipe 58 is cooled. As a result, the first injection valve 44 injects liquid fuel, and at least a portion of the injected fuel evaporates in the intake passage. The evaporation of the fuel reduces the intake air temperature, and the density of the intake air can be increased.

[0028] The evaporation space 56 and the inner space of the cooling pipe 58 are separated by the pipe wall of the cooling pipe 58. Therefore, the fuel flowing through the first feed passage 46 including the cooling pipe 58 is not affected by the pressure in the evaporation space 56, and the pressure in the fuel tank 12 acts directly on the first injection valve 44. The cooling pipe 58 may extend linearly across the evaporation space 56, or may extend in a serpentine manner. Fins for heat dissipation may be provided on the outer circumferential surface of the cooling pipe 58.

[0029] The amount of fuel sprayed from the sprayer 60 may be controlled based on the temperature of the fuel immediately before being sent to the first injector 44, detected by the fuel temperature sensor 47. When the temperature of the fuel is high, the amount of fuel sprayed is increased so that the fuel sent to the first injector 44 is cooled more. This makes it possible to prevent gaseous fuel from being contained in the fuel injected from the first injector 44. Specifically, the amount of fuel F2 sprayed from the sprayer 60 may be controlled so that the temperature detected by the fuel temperature sensor 47 has a margin of a predetermined temperature difference or more with respect to the temperature on the saturated vapor pressure line for the pressure of the supplied fuel F1. For example, the temperature of the fuel F1 is controlled to a temperature 10° C. or more lower than the temperature on the saturated vapor pressure line for the supply pressure of the fuel F1.

[0030] The amount of fuel injected from the first injector 44 is controlled based on an intake air amount sensor (not shown) provided in the intake passage 22 and an excess air ratio sensor 36 provided in the exhaust passage 24. The amount of fuel supplied relative to the amount of intake air is controlled so that the excess air ratio detected by the excess air ratio sensor 36 becomes 1, that is, so that the mixture composition in the cylinder 16 becomes stoichiometric. It is difficult to control the amount of fuel supplied by the second injector 48, which may supply fuel in a gas-liquid mixed state, because the ratio of liquid to gas is unknown. However, since only liquid fuel is supplied to the first injector 44, the amount of fuel supplied can be controlled with high precision.

[0031] The state of the fuel delivered by the fuel supply device 14 will be described with reference to FIG. 2. FIG. 2 is a diagram of the saturated vapor pressure of ammonia, with the horizontal axis representing the temperature of the fuel (ammonia) and the vertical axis representing the pressure of the fuel (ammonia). The pressure is indicated by gauge pressure. The fuel is liquid in the upper left region on either side of the saturated vapor pressure line, and gas in the lower right region. In the following description, the fuel flowing through the first delivery passage 46 will be referred to as fuel F1, and the fuel flowing through the second delivery passage 50 will be referred to as fuel F2.

[0032] The pressure inside the fuel tank 12 is the saturated vapor pressure at the temperature inside the fuel tank 12. If the temperature inside the fuel tank is 30°C, the state of the fuel immediately after it is discharged from the fuel tank 12 (position indicated by A in Fig. 1) is the state indicated by point A on the saturated vapor pressure line in Fig. 2, which corresponds to a temperature of 30°C.

[0033] The fuel F2 flowing through the second feed passage 50 is atomized by the atomizer 60 and evaporated in the chamber 54 of the cooler 52. The temperature in the chamber 54 decreases due to the latent heat of evaporation. If some of the fuel does not evaporate and remains as a liquid, the state of the fuel F2 moves along the saturated vapor pressure line to a state where the temperature and pressure are decreased, for example, as shown by point B. This state is the state of the fuel F2 from the chamber 54 to the second injector 48.

[0034] The fuel F1 flowing through the first supply passage 46 is cooled and its temperature decreases as it passes through the cooling pipe 58 of the cooler 52. Meanwhile, the pressure of the fuel F1 does not change because it is maintained in a liquid state. The fuel F1 reaches a state indicated by point C, which is moved leftward from point A in FIG. 2. Point C is away from the saturated vapor pressure line, so evaporation is suppressed even if the temperature of the fuel F1 increases as a result of receiving heat from the outside in the process of reaching the first injector 44.

[0035] FIG. 3 is a diagram showing another embodiment of the fuel supply device. In FIG. 3, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In the fuel supply device 70 shown in FIG. 3, the second fuel supply system 72 has an evaporator 74 that evaporates the liquid fuel that remains unevaporated among the fuel F2 sent from the chamber 54 of the cooler 52. The evaporator 74 is disposed between the chamber 54 and the second injection valve 48. The evaporator 74 heats and evaporates the fuel F2 by utilizing the heat of the cooling water of the engine 10 or the heat of an electric heater. The state of the fuel F2 downstream of the evaporator 74 is the state shown by point D in FIG. 2. The fuel F2 supplied by the second fuel supply system 42 is only gas, and the amount of fuel supplied from the second injection valve 48 can be easily controlled compared to the case where the fuel F2 is in a gas-liquid mixed state.

[0036] Fig. 4 is a diagram showing still another embodiment of the fuel supply device. In Fig. 4, the same components as those shown in Figs. 1 and 3 are given the same reference numerals, and the description thereof will be omitted. A fuel supply device 80 shown in Fig. 4 differs from the fuel supply device 70 shown in Fig. 3 in that a second fuel supply system 82 has a regulator 84 provided downstream of the evaporator 74. The regulator 84 sets the pressure of the fuel F2 downstream of the regulator 84 to a fixed value. This makes the pressure of the fuel F2 supplied to the second injector 48 constant, making it easy to control the amount of fuel supplied from the second injector 48.

[0037] FIG. 5 is a diagram showing yet another embodiment of the fuel supply device. In FIG. 5, the same components as those shown in FIGS. 1 and 3 are given the same reference numerals, and the description thereof is omitted. The fuel supply device 90 shown in FIG. 5 includes a first fuel supply system 40 and a second fuel supply system 72 for supplying ammonia, as well as an auxiliary fuel supply system 92 for supplying a fuel with better ignition properties than ammonia, such as hydrogen. The fuel supply device 90 shown in FIG. 5 has a configuration in which the auxiliary fuel supply system 92 is added to the fuel supply device 70 shown in FIG. 3. The auxiliary fuel supply system 92 has an auxiliary fuel injection valve 94 for injecting auxiliary fuel toward the intake air flowing through the intake air flow passage 22, and an auxiliary fuel delivery passage 98 for delivering auxiliary fuel from an auxiliary fuel tank 96 to the auxiliary fuel injection valve 94. When ammonia is used as a fuel, the combustion speed is slow, and therefore the ignition properties are poor. In order to improve the ignition properties, a fuel with a high combustion speed and good ignition properties, such as hydrogen, is mixed. The auxiliary fuel supply system 92 may be incorporated into the fuel supply system 14 shown in FIG. 1, or may be incorporated into the fuel supply system 80 shown in FIG.

[0038] FIG. 6 is a diagram showing yet another embodiment of the fuel supply device. In FIG. 6, the same components as those shown in FIGS. 1 and 3 are denoted by the same reference numerals, and the description thereof will be omitted. The fuel supply device 100 shown in FIG. 6 is different from the fuel supply device 70 shown in FIG. 3 in that the second fuel supply system 102 has a reformer 104 provided downstream of the evaporator 74. The reformer 104 converts at least a part of the fuel into hydrogen, and the hydrogen is injected from the second injection valve 48 toward the intake air. The reformer 104 converts the fuel into hydrogen using a catalyst. In addition, in order to activate the catalyst, the reformer 104 may be provided with an electric heater for heating the catalyst.

[0039] Fig. 7 is a diagram showing yet another embodiment of the fuel supply device. In Fig. 7, the same components as those shown in Figs. 1, 3, and 6 are given the same reference numerals, and the description thereof will be omitted. The fuel supply device 110 shown in Fig. 7 is obtained by adding a bypass passage 114 in which the second fuel supply system 112 bypasses the reformer 104 and a third injection valve 116 that injects the fuel F2 sent through the bypass passage 114 toward the intake air, to the fuel supply device 100 shown in Fig. 6. The amount of fuel F2 flowing to the reformer 104 may be adjustable in order to adjust the amount of hydrogen produced.

[0040] <Additional Notes> [1] A fuel supply device that supplies a liquefied gas fuel to an engine, a first fuel supply system that supplies fuel stored in a liquefied state in a fuel tank to an intake air of the engine, the first fuel supply system having a first injection valve that injects the liquefied fuel into the intake air of the engine and a first supply flow path that supplies fuel to the first injection valve; a second fuel supply system that supplies the fuel stored in a liquefied state in the fuel tank toward the intake air of the engine, the second fuel supply system having a second injection valve that injects fuel in a gaseous or gas-liquid mixed state into the intake air of the engine, and a second delivery passage that delivers fuel to the second injection valve; a cooler for cooling fuel flowing through the first feed passage, the cooler including: a chamber forming a part of the second feed passage and defining an evaporation space; a cooling pipe forming a part of the first feed passage and extending within the evaporation space; and an atomizer for atomizing the fuel flowing through the second feed passage and supplying the atomized fuel to the evaporation space, the cooling pipe being cooled by the latent heat of evaporation of the atomized fuel; A fuel supply system comprising: [2] The fuel supply device according to the above item [1], wherein an amount of fuel supplied to the engine is adjusted by the fuel supplied by the first fuel supply system. [3] The fuel supply device according to the above item [1] or [2], wherein the second fuel supply system has an evaporator provided downstream of the cooler and evaporating fuel that has not evaporated in the cooler. [4] The fuel supply device according to the above item [3], wherein the second fuel supply system has a reformer provided downstream of the evaporator and configured to convert at least a portion of the fuel into hydrogen. [5] The fuel supply device according to any one of the above items [1] to [3], further comprising an auxiliary fuel supply system that supplies a fuel having better ignition ability than the liquefied gas fuel as an auxiliary fuel toward the intake air of the engine. [6] A fuel supply device according to any one of the above items [1] to [5], wherein a temperature of the fuel supplied by the first supply passage is controlled by an amount of the fuel supplied by the sprayer. [7] The fuel supply device according to any one of the above items [1] to [6], wherein the liquefied gas as the fuel is ammonia. [Explanation of symbols]

[0041] 10 engine, 12 fuel tank, 14, 70, 80, 90, 100, 110 fuel supply system, 16 cylinder, 22 intake passage, 24 exhaust passage, 26 intake port, 30 exhaust port, 34 exhaust purification device, 36 excess air ratio sensor, 40 first fuel supply system, 42, 72, 82, 102 second fuel supply system, 44 first injector, 46 first delivery passage, 47 fuel temperature sensor, 48 second injector, 50 second delivery passage, 52 cooler, 54 chamber, 56 evaporation space, 58 cooling pipe, 60 sprayer, 74 evaporator, 84 regulator, 92 auxiliary fuel supply system, 94 auxiliary fuel injector, 96 auxiliary fuel tank, 104 reformer.

Claims

1. A fuel supply device that supplies a liquefied gas fuel to an engine, a first fuel supply system that supplies fuel stored in a liquefied state in a fuel tank to an intake air of the engine, the first fuel supply system having a first injection valve that injects the liquefied fuel into the intake air of the engine and a first supply flow path that supplies fuel to the first injection valve; a second fuel supply system that supplies fuel stored in a liquefied state in the fuel tank toward an intake air of the engine, the second fuel supply system having a second injection valve that injects fuel in a gaseous or gas-liquid mixed state into the intake air of the engine, and a second supply flow path that supplies fuel to the second injection valve; a cooler for cooling fuel flowing through the first feed passage, the cooler including: a chamber forming a part of the second feed passage and defining an evaporation space; a cooling pipe forming a part of the first feed passage and extending within the evaporation space; and an atomizer for atomizing the fuel flowing through the second feed passage and supplying the atomized fuel to the evaporation space, the cooling pipe being cooled by the latent heat of evaporation of the atomized fuel; A fuel supply system comprising:

2. 2. The fuel supply system of claim 1, wherein the amount of fuel supplied to the engine is regulated by the fuel supplied by the first fuel supply system.

3. 2. The fuel supply system according to claim 1, wherein the second fuel supply system has an evaporator provided downstream of the cooler for evaporating fuel that is not evaporated by the cooler.

4. 4. The fuel supply system according to claim 3, wherein the second fuel supply system is provided downstream of the evaporator and includes a reformer that converts at least a portion of the fuel into hydrogen.

5. 2. A fuel supply system according to claim 1, further comprising an auxiliary fuel supply system for supplying a fuel having better ignition ability than the liquefied gas fuel as an auxiliary fuel toward the intake air of the engine.

6. 2. The fuel supply system of claim 1, wherein a temperature of the fuel supplied by the first delivery passage is controlled by the amount of fuel supplied by the atomizer.

7. 7. The fuel supply system according to claim 1, wherein the liquefied gas as the fuel is ammonia.

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