Method and device for discharging residual gas fuel in gas fuel engine unit

Abstract

An inert gas introduction path 32 through which inert gas is introduced into a fuel supply path 22 that supplies hydrogen to an engine 10 is provided. A control device 70 comprising an electronic control device performs a gas fuel supply stop process for operating a gas fuel supply control mechanism 40 after an engine 10 is stopped, to cut off communication between a gas fuel source 20 and the fuel supply path 22, and subsequently performs a supply path fuel discharge process for releasing, into the atmosphere, gas fuel remaining in the fuel supply path 22. The supply path fuel discharge control process is performed by introducing inert gas from an inert gas source 30 into the fuel supply path 22 via an inert gas introduction control mechanism 60, in a state where the fuel supply path 22 is open to the atmosphere via a gas release mechanism 50.

Description

Method and device for discharging residual gaseous fuel in a gaseous fuel engine unit

[0001] The present invention relates to an engine unit (referred to as a "gaseous fuel engine unit" in the present invention) that includes an internal combustion engine that operates by burning gaseous fuel such as hydrogen, and a fuel supply passage that supplies gaseous fuel to the engine, and relates to a method for discharging residual gaseous fuel, which discharges gaseous fuel so that no gaseous fuel remains in the fuel supply passage, or in the fuel supply passage and the engine, when the engine is stopped, and to a residual gaseous fuel discharge device that carries out the method.

[0002] In this invention, the term "gaseous fuel engine unit" broadly includes those equipped with a fuel supply passage for supplying gaseous fuel such as hydrogen gas to an engine, and includes both engine units equipped with a gaseous fuel-only engine that can use only gaseous fuel as fuel, as well as engine units equipped with an engine that can use both gaseous fuel and liquid fuel selectively, or a mixture of gaseous fuel and liquid fuel as fuel.

[0003] As society becomes more concerned about environmental issues, the demand for decarbonization is increasing in all fields. The fuels used in internal combustion engines also emit less CO2 during combustion than petroleum fuels. ２ Natural gas has low CO emissions when burned. ２ The use of gaseous fuels such as hydrogen gas, which does not produce CO₂, is gaining attention.

[0004] A gaseous fuel engine unit equipped with an engine that operates by burning such gaseous fuel is provided with a fuel supply passage for supplying high-pressure gaseous fuel to the engine from a gaseous fuel source, such as a gaseous fuel cylinder, but if high-pressure gaseous fuel remains in the fuel supply passage even after the engine is stopped, the gaseous fuel remaining in the fuel supply passage will pass through the engine in its stopped state and gradually leak into the engine compartment, creating a risk of the leaked gaseous fuel catching fire.

[0005] Furthermore, if the gaseous fuel is hydrogen gas, and hydrogen gas remains in the fuel supply line or engine, small hydrogen atoms can penetrate into the metal materials of the piping in the fuel supply line or the engine cylinders and pistons, causing "hydrogen embrittlement," which embrittles the materials.This hydrogen embrittlement can lead to failure of the gaseous fuel engine unit and the resulting accidents.

[0006] Therefore, when the engine is stopped, it is desirable to discharge any gaseous fuel remaining in the fuel supply passage or inside the engine to the gaseous fuel supply system or outside the engine, preferably to the engine compartment or outside the hood that houses the engine.

[0007] With regard to the discharge of such residual fuel, Patent Document 1, cited below, describes a method in which, as shown in FIG. 9 , a flow control valve 141 is provided between a hydrogen fuel supply pipe 122 that supplies hydrogen fuel to an engine 110 and a hydrogen source 120, and with this flow control valve 141 closed to stop the supply of fuel from the hydrogen source 120 to the hydrogen fuel supply pipe 122, a cooling mode operation is performed in which the engine 110 is cooled under no load before the engine 110 is stopped, thereby consuming the hydrogen fuel remaining in the hydrogen fuel supply pipe 122, and after the pressure in the hydrogen fuel supply pipe 122 becomes less than a predetermined threshold value TH, the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 is released into the engine room via an air release valve 187.

[0008] Japanese Patent Application Publication No. 2022-149336

[0009] In the engine unit described in the aforementioned Patent Document 1, the cooling mode operation of the engine 110 is performed with the supply of hydrogen fuel from the hydrogen source 120 to the hydrogen fuel supply pipe 122 cut off, so that the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 during cooling mode operation can be consumed without waste, and by subsequently discharging the remaining hydrogen fuel, the amount of hydrogen fuel discharged can be reduced as much as possible, making it possible to operate the engine economically using hydrogen fuel.

[0010] Furthermore, since the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 can be consumed during cooling mode operation to reduce the amount of hydrogen fuel in the hydrogen fuel supply pipe 122 as much as possible, even if the gaseous fuel remaining in the hydrogen fuel supply pipe 122 is subsequently discharged into the engine room via the air release valve 187, it is possible to keep the concentration of hydrogen fuel in the engine room at a low value below the hydrogen concentration that could cause ignition (for example, less than 4%).

[0011] However, the amount of hydrogen fuel remaining in the hydrogen fuel supply pipe 122 increases as the diameter of the hydrogen fuel supply pipe 122 increases and the length of the hydrogen fuel supply pipe 122 increases.

[0012] Therefore, if one attempts to consume the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 during cooling mode operation to a level below a predetermined amount, for example, an amount that will reduce the hydrogen concentration in the engine compartment to less than 4% when discharged into the engine compartment, the thicker and longer the hydrogen fuel supply pipe 122, the longer the cooling mode operation time will need to be, and the pressure (threshold TH) within the hydrogen fuel supply pipe 122 when it is opened to the atmosphere will need to be set lower.

[0013] Therefore, in order to efficiently consume the hydrogen fuel remaining in the hydrogen fuel supply pipe 122, it is necessary to set the termination conditions for the cooling mode operation for each specification of the engine unit, which is cumbersome.

[0014] Furthermore, in the configuration described in the examples of Patent Document 1, as shown in FIG. 9, an engine 110 is employed that can be operated by burning either a liquid fuel such as diesel fuel supplied via a liquid fuel supply unit 181, or hydrogen fuel supplied via a hydrogen fuel supply unit 185. As shown in FIG. 10, after the supply of hydrogen fuel to the hydrogen fuel supply pipe 122 is stopped by closing the flow control valve 141, the amount of liquid fuel supplied via the liquid fuel supply unit 181 is gradually increased until the pressure in the hydrogen fuel supply pipe 122 becomes less than the threshold value TH (t1-t2 in FIG. 10). This transition of the engine operating state from operation using hydrogen fuel to operation using liquid fuel during cooling mode operation enables the engine 110 to operate in a stable state even during cooling mode operation.

[0015] However, if the control method described in Patent Document 1 is applied to an engine unit equipped with a hydrogen-only combustion engine that does not have a liquid fuel supply unit 181 and uses only hydrogen fuel as fuel, and cooling mode operation is performed with fuel supply from the hydrogen source 120 to the hydrogen fuel supply pipe 122 cut off, the engine 110 will be operated by burning only the hydrogen fuel remaining in the hydrogen fuel supply pipe 122, and the amount of fuel supplied to the engine 110 will gradually decrease during cooling mode operation.

[0016] Here, the cooling mode operation is a cooling operation of the engine 110 under no-load conditions, and the rotation speed of the engine 110 during such no-load operation is generally set to the no-load rotation speed, which is the minimum rotation speed that can prevent the occurrence of abnormal combustion, abnormal vibration, etc. in the engine 110.

[0017] However, if the amount and pressure of hydrogen fuel remaining in the hydrogen fuel supply pipe 122 decreases due to the consumption of hydrogen fuel during cooling mode operation, even if the hydrogen fuel supply unit 185 is open to a predetermined opening corresponding to the no-load rotation speed, the amount of hydrogen fuel introduced into the combustion chamber of the engine 110 will gradually decrease, causing the rotation speed of the engine 110 to drop to a speed below the no-load rotation speed, which may cause abnormal combustion or abnormal vibration in the engine 110.

[0018] In particular, if the amount of hydrogen fuel remaining in the hydrogen fuel supply pipe 122 is large, for example because the hydrogen fuel supply pipe 122 is thick and long, the engine 110 will operate for a longer period of time at a rotational speed below the no-load rotational speed during cooling mode operation, and the period of time during which abnormal combustion and abnormal vibration occur will also be longer.As a result, the engine 110, equipment connected to the engine (for example, work machines such as compressors and generators), and couplings connecting the engine 110 to these equipment will be more susceptible to failure or damage.

[0019] Moreover, in the configuration described in Patent Document 1, when the pressure inside the hydrogen fuel supply pipe 122 drops below a predetermined threshold value TH (t2 in Figure 10), the air release valve 187 is opened to open the hydrogen fuel supply pipe 122 to the atmosphere, and cooling mode operation is continued thereafter by burning the liquid fuel supplied from the liquid fuel supply unit 181 (t2-t3 in Figure 10), so that the compressed air generated by the turbocharger 117 passes through the hydrogen fuel supply unit 185 and the hydrogen fuel supply pipe 122 and escapes through the air release valve 187, making it possible to discharge the gaseous fuel remaining in the hydrogen fuel supply pipe 122 at a pressure below the threshold value TH.

[0020] However, when the configuration described in Patent Document 1 is applied to an engine unit equipped with a hydrogen-only combustion engine that does not have a liquid fuel supply unit 181, when the air release valve 187 is opened, the remaining hydrogen fuel in the hydrogen fuel supply pipe 122, which is the only fuel, is no longer introduced into the engine 110, and the engine 110 and the turbocharger 117 stop.As a result, the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 is discharged through the air release valve 187 until the pressure in the hydrogen fuel supply pipe 122 reaches atmospheric pressure, but the structure is such that hydrogen fuel whose pressure has dropped to atmospheric pressure can still remain in the hydrogen fuel supply pipe 122, and there may be cases where the gaseous fuel remaining in the hydrogen fuel supply pipe 122 cannot be completely discharged.

[0021] Therefore, the present invention has been made in consideration of the shortcomings of the above-mentioned conventional technology, and aims to provide a method and device for discharging residual gaseous fuel in a gaseous fuel engine unit, which can discharge gaseous fuel remaining in the fuel supply path, and if necessary, gaseous fuel remaining in the engine, without causing abnormal combustion, abnormal vibration, etc., not only in gaseous fuel engine units which have a liquid fuel supply path in addition to a gaseous fuel supply path, but also in gaseous fuel-only engine units which do not have a liquid fuel supply path.

[0022] The means for solving the problems will be described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are used to clarify the correspondence between the description of the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0023] In order to achieve the above object, the method of discharging residual gaseous fuel in a gaseous fuel engine unit 1 of the present invention comprises, in the gaseous fuel engine unit 1, an engine 10 capable of using gaseous fuel such as hydrogen gas as fuel, and a fuel supply path 22 that supplies gaseous fuel from a gaseous fuel source 20 to the engine 10, providing an inert gas introduction path 32 that introduces inert gas from an inert gas source 30 into the fuel supply path 22, and after the engine 10 is stopped, performing a gaseous fuel supply stop process that stops the supply of gaseous fuel from the gaseous fuel source 20 to the fuel supply path 22, and after the gaseous fuel supply stop process, performing an in-supply path fuel discharge process that releases the gaseous fuel remaining in the fuel supply path 22 to the atmosphere, and performing the inert gas introduction path process by introducing inert gas into the fuel supply path 22 via the inert gas introduction path 32 while the fuel supply path 22 is open to the atmosphere, thereby pushing out the gaseous fuel remaining in the fuel supply path 22 and replacing it with the inert gas, and When a predetermined discharge termination condition is satisfied, the fuel supply path 22 is closed to the atmosphere, the introduction of inert gas into the fuel supply path 22 is stopped, and the fuel discharge process within the supply path is terminated (claim 1).

[0024] The method for discharging residual gaseous fuel of the present invention can include a cranking process in which the engine 10 is rotated by the starter motor 12 after the fuel discharge process within the supply path is completed, and by performing the cranking process until a predetermined cranking termination condition is met, the gaseous fuel remaining in the combustion chamber of the engine 10 can be discharged through the exhaust system 13 of the engine 10 (claim 2).

[0025] The above-mentioned fuel discharge process in the supply path can be terminated when a predetermined discharge time T1 has elapsed or when the gas fuel concentration in the fuel supply path 22 drops below a predetermined threshold C1 (claims 3 and 4).

[0026] In this case, in a configuration in which an air release flow path 54 that releases gaseous fuel remaining in the fuel supply path 22 into the atmosphere is provided in communication with the fuel supply path 22, when the gaseous fuel concentration in the air release flow path 54 falls below the predetermined threshold value C1, it may be determined that the gaseous fuel concentration in the fuel supply path 22 has fallen below the predetermined threshold value C1 (claim 5).

[0027] In addition, the cranking process may be terminated when a predetermined cranking time T2 has elapsed or when the gaseous fuel concentration in the exhaust system 13 of the engine 10 drops below a predetermined threshold C2 (claims 6 and 7).

[0028] Furthermore, in a configuration in which a gaseous fuel pressure regulator 24 is provided in the fuel supply path 22, and the fuel supply path 22 on the primary side of the gaseous fuel pressure regulator 24 is a primary-side fuel supply path 22a, and the fuel supply path 22 on the secondary side of the gaseous fuel pressure regulator 24 is a secondary-side fuel supply path 22b, the fuel discharge process within the supply path can be performed by introducing an inert gas into the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b while the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b are each open to the atmosphere, and the fuel discharge process within the supply path can be completed by finishing opening both the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b to the atmosphere and stopping the introduction of the inert gas into both the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b (claim 8).

[0029] Furthermore, the residual gaseous fuel discharge device in a gaseous fuel engine unit of the present invention is provided in a gaseous fuel engine unit 1 having an engine 10 capable of using gaseous fuel as fuel, and a fuel supply path 22 for supplying gaseous fuel from a gaseous fuel source 20 to the engine 10, and further comprising: an inert gas introduction path 32 communicating between an inert gas source 30 and the fuel supply path 22; a gaseous fuel supply control mechanism 40 for opening and closing between the gaseous fuel source 20 and the fuel supply path 22; an air release mechanism 50 for starting and stopping the release of the fuel supply path 22 to the atmosphere; an inert gas introduction control mechanism 60 for opening and closing between the inert gas source 30 and the fuel supply path 22; and a control device 70 consisting of an electronic control device for controlling the operation of the gaseous fuel supply control mechanism 40, the air release mechanism 50, and the inert gas introduction control mechanism 60, and the control device 70 The present invention provides a gaseous fuel supply stop control means (74) that, after the engine (10) has stopped, operates the gaseous fuel supply control mechanism (40) to execute a gaseous fuel supply stop process for cutting off communication between the gaseous fuel source (20) and the fuel supply path (22) and stopping the supply of gaseous fuel to the fuel supply path (22); and an intra-supply path fuel discharge control means (75) that, after the gaseous fuel supply stop process is executed by the gaseous fuel supply stop control means (74), executes an intra-supply path fuel discharge process for releasing the gaseous fuel remaining in the fuel supply path (22) to the atmosphere, wherein the intra-supply path fuel discharge control means (75) operates the air release mechanism (50) to open the fuel supply path (22) to the atmosphere, and operates the inert gas introduction control mechanism (60) to introduce inert gas from the inert gas source (30) into the fuel supply path (22), thereby executing the intra-supply path fuel discharge process, and When a predetermined discharge termination condition is satisfied, the air release mechanism 50 is operated to terminate the opening of the fuel supply path 22 to the atmosphere, and the inert gas introduction control mechanism 60 is operated to stop the introduction of inert gas into the fuel supply path 22, thereby terminating the fuel discharge process within the supply path (claim 9).

[0030] In the residual gaseous fuel discharge device 2 configured as described above, the gaseous fuel supply control mechanism 40 is configured by a gaseous fuel supply valve 41 consisting of an air-operated valve that opens and closes between the gaseous fuel source 20 and the fuel supply path 22, a gaseous fuel supply valve control circuit 42 that introduces inert gas from the inert gas source 30 into the gaseous fuel supply valve 41 as an operating pressure, and a gaseous fuel supply control electromagnetic valve 43 that establishes and cuts off communication between the inert gas source 30 and the gaseous fuel supply valve control circuit 42, The air release mechanism 50 (50a, 50b) is composed of an air release valve 51 (51a, 51b) consisting of an air-operated valve that opens the fuel supply path 22 (22a, 22b) to the atmosphere, an air release valve control circuit 52 (52a, 52b) that introduces the inert gas from the inert gas source 30 into the air release valve 51 (51a, 51b) at an operating pressure, and an air release valve control solenoid valve 53 (53a, 53b) that establishes and closes communication between the inert gas source 30 and the air release valve control circuit 52 (52a, 52b), and the inert gas introduction control mechanism 60 is composed of an electromagnetic on-off valve 61 provided in the inert gas introduction path 32, and the gas fuel supply control solenoid valve 43 is configured to be operable by the gas fuel supply stop control means 74 of the control device 70, and The solenoid valve 53 (53a, 53b) for controlling the air release valve and the solenoid valve 61, which is the inert gas introduction control mechanism 60, may be configured to be operable by the fuel discharge control means 75 in the supply path of the control device 70 (claim 10).

[0031] In the residual gaseous fuel discharge device 2 having the above-mentioned configuration, the inert gas source 30 may be provided with an inert gas pressure regulator 30b for adjusting the pressure of the inert gas, and the secondary side of the inert gas pressure regulator 30b may be connected to the inert gas introduction path 32 via the electromagnetic opening / closing valve 61, the gaseous fuel supply valve control circuit 42 via the gaseous fuel supply control electromagnetic valve 43, and the air release valve control circuit 52 (52a, 52b) via the air release valve control electromagnetic valve 53 (53a, 53b) (Claim 11).

[0032] In addition, the residual gas fuel discharge device 2 of the present invention may also be configured so that the control device 70 realizes a cranking control means 77 that performs a cranking process to rotate the starter motor 12 of the engine 10 after the fuel discharge process in the supply path by the fuel discharge control means 75 is completed, until a predetermined cranking termination condition is met (Claim 12).

[0033] The fuel discharge control means 75 in the supply path can be configured to terminate the fuel discharge process in the supply path with the discharge termination condition being the lapse of a predetermined discharge time T1 or a decrease in the gaseous fuel concentration in the fuel supply path 22 to below a predetermined threshold C1 (claim 13).

[0034] In this case, in a configuration in which an air release flow path 54 that releases gaseous fuel remaining in the fuel supply path 22 into the atmosphere is provided in communication with the fuel supply path 22, the fuel discharge control means 75 in the supply path may be configured to determine that the gaseous fuel concentration in the fuel supply path 22 has fallen below the predetermined threshold value C1 when the gaseous fuel concentration in the air release flow path 54 falls below the predetermined threshold value C1 (claim 14).

[0035] In addition, the cranking control means 77 can be configured to terminate the cranking process when a predetermined cranking time T2 has elapsed or when the gaseous fuel concentration in the engine's exhaust system 13 drops below a predetermined threshold C2 (claim 15).

[0036] Furthermore, in a configuration in which a gaseous fuel pressure regulator 24 is provided in the fuel supply path 22, and the fuel supply path 22 on the primary side of the gaseous fuel pressure regulator 24 is a primary-side fuel supply path 22a, and the fuel supply path 22 on the secondary side of the gaseous fuel pressure regulator 24 is a secondary-side fuel supply path 22b, the inert gas introduction path 32 is communicated with the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b, the air release mechanism 50 is provided with, as the air release valve 51, a primary-side air release valve 51a that opens the primary-side fuel supply path 22a to the atmosphere, and a secondary-side air release valve 51b that opens the secondary-side fuel supply path 22b to the atmosphere, and the air release valve control circuit 52 is provided with, as the air release valve control circuit 52, a primary-side air release valve control circuit 52a that introduces an operating pressure to the primary-side air release valve 51a, and a secondary-side air release valve control circuit 52b that introduces an operating pressure to the secondary-side air release valve 51b, The air release valve control solenoid valve 53 may be provided with a primary side air release valve control solenoid valve 53a that connects and disconnects the communication between the inert gas source 30 and the primary side air release valve control circuit 52a, and a secondary side air release valve control solenoid valve 53b that connects and disconnects the communication between the inert gas source 30 and the secondary side air release valve control circuit 52b (Claim 16).

[0037] According to the configuration of the present invention described above, the method and device for discharging residual gaseous fuel in the gaseous fuel engine unit 1 of the present invention, after the engine 10 is stopped, the gaseous fuel remaining in the fuel supply path 22 is discharged and the fuel supply path 22 is filled with an inert gas such as nitrogen gas to replace the gaseous fuel, thereby preventing the gaseous fuel in the fuel supply path 22 from leaking into the engine room via the stopped engine 10, etc., and effectively preventing hydrogen embrittlement and oxidation of metal piping, etc., installed in the fuel supply path 22.

[0038] Furthermore, in the configuration of the present invention, after the engine 10 is stopped, inert gas is introduced from the inert gas source 30 to discharge any fuel remaining in the fuel supply path 22. Therefore, even when the configuration of the present invention is applied to an engine unit that can use both gaseous fuel and liquid fuel, or even when the configuration of the present invention is applied to a gaseous fuel-only engine unit, there is no need to worry about abnormal combustion, abnormal vibration, or any resulting malfunctions occurring in the engine 10 when removing any gaseous fuel remaining in the fuel supply path, as in the engine unit introduced in the above-mentioned Patent Document 1.

[0039] Furthermore, in the configuration of the present invention, after the gaseous fuel in the fuel supply path 22 is replaced with an inert gas, the opening of the fuel supply path 22 to the atmosphere and the introduction of the inert gas are stopped, thereby sealing the inert gas within the fuel supply path 22.

[0040] In a configuration in which the remaining gaseous fuel in the fuel supply passage 22 is replaced with inert gas and then the engine's starter motor is activated to crank the engine, the gaseous fuel remaining in the combustion chamber of the engine 10 can also be discharged outside the aircraft via the exhaust system 13 of the engine 10, and is replaced with the inert gas in the fuel supply passage 22 that has been drawn into the combustion chamber, thereby preventing oxidation of the engine's cylinders and pistons and preventing hydrogen embrittlement from occurring even when the gaseous fuel is hydrogen gas.

[0041] The above-mentioned fuel discharge process in the supply path and cranking process may be terminated after a predetermined discharge time T1 or cranking time T2 has elapsed, in which case the device configuration and control method can be simplified. However, there are disadvantages in that the process may end before the gaseous fuel remaining in the fuel supply path 22 or engine 10 is completely discharged, or the process may continue unnecessarily until the predetermined discharge time T1 or cranking time T2 has elapsed even if the discharge of the remaining gaseous fuel has been completed.

[0042] On the other hand, in a configuration in which the process of discharging residual gaseous fuel is terminated when the gaseous fuel concentration in the fuel supply passage 22 or the exhaust system 13 of the engine 10 falls below predetermined thresholds C1 and C2, it becomes necessary to add a sensor to detect the gaseous fuel concentration, but this has the advantage of allowing the residual gaseous fuel to be discharged reliably and efficiently.

[0043] Furthermore, in a configuration in which a pressure regulator 24 for gaseous fuel is provided in the fuel supply path 22, the residual gaseous fuel in the fuel supply path 22 can be reliably discharged by discharging the residual gaseous fuel and replacing it with an inert gas in the fuel supply path 22a on the primary side of the pressure regulator 24 and the fuel supply path 22b on the secondary side, respectively.

[0044] In addition, in the residual gaseous fuel discharge device 2 of the present invention, the on-off valves [gaseous fuel supply valve 41, air release valve 51 (51a, 51b)] that open and close the flow path through which gaseous fuel, which is a flammable gas, passes are made to be air-operated valves that are operated by the introduction of inert gas, thereby achieving explosion prevention, and by using solenoid valves [gaseous fuel supply control solenoid valve 43, air release valve control solenoid valve 53 (53a, 53b)] as control valves that control the introduction and stopping of inert gas to these air-operated valves [gaseous fuel supply valve 41, air release valve 51 (51a, 51b)], the complicated opening and closing operations of each part can be automatically controlled by the control device 70.

[0045] 1 is an explanatory diagram of a residual gas fuel discharge device for a gaseous fuel engine unit according to a first embodiment; a functional block diagram of the residual gas fuel discharge device for a gaseous fuel engine unit according to a first embodiment; a flow diagram showing the operation of the residual gas fuel discharge device for a gaseous fuel engine unit according to a first embodiment; a time chart showing the operation of each part of the residual gas fuel discharge device for a gaseous fuel engine unit according to a first embodiment; an explanatory diagram of a residual gas fuel discharge device for a gaseous fuel engine unit according to a second embodiment; a functional block diagram of the residual gas fuel discharge device for a gaseous fuel engine unit according to a second embodiment; a flow diagram showing the operation of the residual gas fuel discharge device for a gaseous fuel engine unit according to a second embodiment; a time chart showing the operation of each part of the residual gas fuel discharge device for a gaseous fuel engine unit according to a second embodiment; an explanatory diagram of a gaseous fuel engine unit equipped with a conventional residual fuel discharge device (corresponding to Figure 1 of Patent Document 1); a time chart showing the operation of each part of a gaseous fuel engine unit equipped with a conventional residual fuel discharge device (corresponding to Figure 4 of Patent Document 1).

[0046] Hereinafter, the configuration of the residual gaseous fuel discharge device in a gaseous fuel engine unit of the present invention will be described with reference to the accompanying drawings.

[0047] In the following explanation, an example will be given in which hydrogen gas is used as the gaseous fuel; however, the application of the present invention is not limited to gaseous fuel engine units (hydrogen engine units) that use hydrogen gas as fuel, but can also be applied to gaseous fuel engine units that use other known gaseous fuels such as natural gas as fuel.

[0048] In addition, in the following explanation, an example will be described in which nitrogen gas is used as the inert gas, but usable inert gases are not limited to nitrogen gas, and other known inert gases such as argon gas can also be used.

[0049] [Overall Configuration of Gaseous Fuel Engine Unit] FIG. 1 shows the overall configuration of a gaseous fuel engine unit (hydrogen engine unit) equipped with a residual gaseous fuel discharge device of the present invention.

[0050] In FIG. 1 , reference numeral 1 denotes a gaseous fuel engine unit (hydrogen engine unit), and this gaseous fuel engine unit 1 includes an engine 10 as an internal combustion engine that operates by burning hydrogen gas as a gaseous fuel, and a fuel supply path (hydrogen gas supply path) 22 that supplies hydrogen gas from a gaseous fuel source (hydrogen source) 20 to the engine 10.

[0051] In this embodiment, the engine 10 is configured as a hydrogen-only engine that operates using only hydrogen gas as fuel. However, the present invention can also be applied to a gas fuel engine unit in which the gas fuel engine unit 1 is configured with a liquid fuel supply passage (not shown) that supplies liquid fuel such as diesel or gasoline to the engine 10, so that the engine can be operated by selectively supplying hydrogen fuel and liquid fuel, or by simultaneously supplying hydrogen fuel and liquid fuel.

[0052] In the illustrated example, the gaseous fuel source 20 is configured by a hydrogen gas cylinder, but instead of this configuration, a tank filled with liquefied hydrogen may be used as the hydrogen source, as in the prior art described with reference to Figure 9. In this case, the gaseous fuel source 20 may include, along with the liquefied hydrogen tank, a vaporizer for vaporizing the liquefied hydrogen to obtain hydrogen gas.

[0053] The gaseous fuel source 20 is connected to the fuel supply path 22 via a check valve CV1 and a gaseous fuel supply valve 41 of a gaseous fuel supply control mechanism 40 described later. The gaseous fuel supply valve 41 opens and closes to control the connection and disconnection between the gaseous fuel source 20 and the fuel supply path 22, and the check valve CV1 prevents gas in the fuel supply path 22 from flowing into the gaseous fuel source 20.

[0054] In the embodiment shown in FIG. 1, a gaseous fuel pressure regulator 24 is provided at an intermediate position of the fuel supply passage 22 to adjust the pressure of the hydrogen gas to a predetermined pressure. However, this gaseous fuel pressure regulator 24 may be provided at a position closer to the gaseous fuel source 20, and its placement is not limited to the position shown in the figure.

[0055] Furthermore, if the gaseous fuel source 20 is provided with a pressure adjusting means such as a pressure regulator, the provision of the pressure regulator 24 for the fuel supply passage 22 can be omitted.

[0056] The engine 10, which receives gaseous fuel via a fuel supply line 22, is provided with an engine control unit (ECU) 11 that controls the operation of the engine 10 and a starter motor 12 for starting the engine 10. The engine 10 is also configured so that the engine 10 can be started, stopped, and its speed controlled by a control device 70, which is an electronic control device such as a microcontroller provided in the gaseous fuel engine unit 1.

[0057] Also, reference numeral 13 in FIG. 1 denotes an engine exhaust system consisting of an exhaust pipe, a muffler, etc. (neither of which are shown), which discharges the gas produced when hydrogen gas is burned in the combustion chamber of the engine 10 outside the aircraft as exhaust gas.

[0058] [Residual gas fuel discharge device] (Example 1) (1) Overall configuration The gas fuel engine unit 1 configured as described above is provided with a residual gas fuel discharge device 2 that discharges hydrogen gas remaining in the fuel supply path 22 described above, or hydrogen gas remaining in the fuel supply path 22 and hydrogen gas remaining in the engine 10, to the outside of the machine when the engine 10 is stopped, and replaces the gas in the fuel supply path 22 and the engine 10 with nitrogen gas.

[0059] This residual gas fuel discharge device 2 is composed of an inert gas inlet path 32 that introduces inert gas (nitrogen gas) from an inert gas source (nitrogen source) 30 into the fuel supply path 22, a gas fuel supply control mechanism 40 that opens and closes between the hydrogen source 20 and the fuel supply path 22 to control the start and stop of the introduction of hydrogen gas into the fuel supply path 22, an air release mechanism 50 that controls the start and stop of opening the fuel supply path 22 to the atmosphere, an inert gas introduction control mechanism 60 that controls the connection and cut-off of the inert gas inlet path 32 to the inert gas source 30, and a control device 70 that controls the operation of these mechanisms.

[0060] (2) Inert Gas Inlet Path 32 The inert gas inlet path 32 is a flow path that introduces inert gas from an inert gas source 30 into the fuel supply path 22 .

[0061] In the embodiment shown in FIG. 1, the inert gas source 30 is composed of a nitrogen gas cylinder 30a filled with nitrogen gas, and a nitrogen gas pressure regulator 30b that adjusts the nitrogen gas from the nitrogen gas cylinder 30a to a predetermined pressure, and the inert gas introduction path 32 is connected to the secondary side of this nitrogen gas pressure regulator 30b via an electromagnetic opening / closing valve 61.

[0062] In the illustrated configuration in which the gaseous fuel pressure regulator 24 is provided in the fuel supply path 22, the secondary side of the inert gas introduction path 32 is branched into two paths, one of which is connected to a primary-side fuel supply path 22 a, which is the fuel supply path 22 on the primary side of the gaseous fuel pressure regulator 24, via a check valve CV2, and the other of which is connected to a secondary-side fuel supply path 22 b, which is the fuel supply path 22 on the secondary side of the gaseous fuel pressure regulator 24, via a check valve CV3.

[0063] In this way, by connecting the inert gas introduction path 32 to the fuel supply path 22 (22a, 22b) via the check valves CV2 and CV3, hydrogen gas in the fuel supply path 22 (22a, 22b) is prevented from flowing into the inert gas introduction path 32.

[0064] (3) Gaseous fuel supply control mechanism 40: Reference numeral 40 in FIG. 1 denotes a gaseous fuel supply control mechanism. This gaseous fuel supply control mechanism 40 establishes or blocks communication between the gaseous fuel source 20 and the fuel supply path 22, and controls the start and stop of supply of hydrogen gas to the fuel supply path 22.

[0065] In the illustrated embodiment, the gaseous fuel supply control mechanism 40 is composed of a gaseous fuel supply valve 41, which is an air-operated on-off valve provided at the primary end of the fuel supply passage 22, a gaseous fuel supply valve control circuit 42 that introduces nitrogen gas from the nitrogen source 30 as operating pressure into the gaseous fuel supply valve 41, and a gaseous fuel supply control solenoid valve 43 that is a solenoid valve (three-way solenoid valve) that connects the gaseous fuel supply valve control circuit 42 to the nitrogen source 30 or opens it to the atmosphere.

[0066] In this way, explosion prevention is achieved by using an air-operated valve that operates using inert gas as its operating pressure rather than a solenoid valve for the gas fuel supply valve 41 that controls the opening and closing of the flow path of the gas fuel, which is a flammable gas, while a solenoid valve is used for the gas fuel supply control solenoid valve 43 that opens and closes the flow path of the inert gas, which does not require explosion prevention, making it easier to perform electrical control by the control device 70, which will be described later.

[0067] By providing the gaseous fuel supply control mechanism 40 having the above-described configuration, when the gaseous fuel supply control solenoid valve 43 is operated to connect the inert gas source 30 to the gaseous fuel supply valve control circuit 42, inert gas is introduced from the inert gas source 30 as an operating pressure into the gaseous fuel supply valve 41, causing the gaseous fuel supply valve 41 to open and introduce hydrogen gas, which is the gaseous fuel, into the fuel supply path 22.

[0068] On the other hand, when the gas fuel supply control solenoid valve 43 is operated to cut off communication between the inert gas source 30 and the gas fuel supply valve control circuit 42 and the gas fuel supply valve control circuit 42 is opened to the atmosphere, the introduction of inert gas as an operating pressure to the gas fuel supply valve 41 is stopped, and the gas fuel supply valve 41 is closed by the biasing force of the return spring, thereby stopping the introduction of hydrogen gas into the fuel supply path 22.

[0069] (4) Inert Gas Introduction Control Mechanism 60 The inert gas introduction control mechanism 60 controls the start and stop of introduction of nitrogen gas, which is an inert gas, into the fuel supply path 22 (22a, 22b) by connecting or blocking communication between the inert gas source 30 and the inert gas introduction path 32.

[0070] The inert gas introduction control mechanism 60, which controls the opening and closing of the inert gas flow path, does not need to be explosion-proof, and in the illustrated embodiment, an electromagnetic opening / closing valve (two-way electromagnetic valve) 61 is provided as the inert gas introduction control mechanism 60 between the inert gas source 30 and the inert gas introduction path 32, and the opening and closing of the electromagnetic opening / closing valve 61 makes it possible to start and stop the introduction of nitrogen gas into the fuel supply path 22 (22a, 22b) via the inert gas introduction path 32.

[0071] (5) Air Release Mechanism 50 The air release mechanism 50 controls the start and stop of the opening of the fuel supply passage 22 (22a, 22b) to the atmosphere.

[0072] In the embodiment shown in FIG. 1, air discharge flow paths 54a, 54b are provided on the secondary side relative to the communication position of the inert gas introduction path 32, branching off from the primary-side fuel supply path 22a and the secondary-side fuel supply path 22b, respectively, and the air discharge flow paths 54a, 54b are extended to the outside of the aircraft.

[0073] The air release flow paths 54a, 54b are controlled to open and close by the air release mechanism 50 (primary side air release mechanism 50a, secondary side air release mechanism 50b), so that the opening of the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) to the atmosphere can be started or stopped.

[0074] The opening and closing of the air release flow paths 54a, 54b through which hydrogen, a flammable gas, can flow, is performed by an air release valve 51 (primary side air release valve 51a, secondary side air release valve 51b) configured by an air valve that operates using nitrogen gas introduced from an inert gas source as its operating pressure for explosion prevention, and an air release valve control circuit 52 (primary side air release valve 51a, secondary side air release valve 51b) that introduces nitrogen gas from a nitrogen source 30 as its operating pressure into the air release valve 51 (primary side air release valve 51a, secondary side air release valve 51b). The aforementioned air release mechanism 50 (primary side air release mechanism 50a, secondary side air release mechanism 50b) is configured by providing an air release valve control circuit 52 (primary side air release valve control circuit 52a, secondary side air release valve control circuit 52b) and an air release valve control solenoid valve 53 (primary side air release valve control solenoid valve 53a, secondary side air release valve control solenoid valve 53b) consisting of a three-way solenoid valve that connects this air release valve control circuit 52 (primary side air release valve control circuit 52a, secondary side air release valve control circuit 52b) to the nitrogen source 30 or opens it to the atmosphere.

[0075] As a result, when the air release valve control solenoid valve 53 (53a, 53b) connects the air release valve control circuit 52 (52a, 52b) to the nitrogen source 30, operating pressure (nitrogen gas) is introduced into the air release valve 51 (51a, 51b), and the air release valve 51 (51a, 51b) opens, thereby starting to open the fuel supply path 22 (22a, 22b) to the atmosphere.

[0076] On the other hand, when the air release valve control solenoid valve 53 (53a, 53b) cuts off communication between the air release valve control circuit 52 (52a, 52b) and the nitrogen source 30 and opens the air release valve control circuit 52 (52a, 52b) to the atmosphere, the introduction of the operating pressure (nitrogen gas) stops and the air release valve 51 (51a, 51b) closes due to the biasing force of the return spring, thereby stopping the opening of the fuel supply path 22 (22a, 22b) to the atmosphere.

[0077] In the illustrated example, the air release flow paths 54a, 54b are provided with a primary side air release valve 51a and a secondary side air release valve 51b, respectively, and a primary side air release valve control solenoid valve 53a and a secondary side air release valve control solenoid valve 53b are provided to control the start and stop of introduction of inert gas into the primary side air release valve 51a and the secondary side air release valve 51b, respectively. However, instead of this configuration, for example, the start and stop of introduction of inert gas into both the primary side air release valve 51a and the secondary side air release valve 51b may be controlled by a single air release valve control solenoid valve, or a single air release valve may be provided on the secondary side of the joining position of the air release flow paths 54a, 54b, and a single air release valve control solenoid valve may be provided to control the start and stop of introduction of inert gas into this air release valve. The configuration of the air release mechanism 50 is not limited to the configuration shown in the figure, as long as it is configured to be able to control the start and stop of opening of the primary side fuel supply path 22a and the secondary side fuel supply path 22b to the atmosphere.

[0078] (6) Control device 70 The control device 70 is composed of an electronic control device such as a microcontroller, and in addition to controlling the operation of the engine 10 described above, by executing a pre-stored program, the control device 70 realizes each means shown in the functional block diagram of Figure 2, thereby controlling the operation of the gas fuel supply control mechanism 40, the air release mechanism 50, and the inert gas introduction control mechanism 60 described above.

[0079] In the embodiment shown in FIGS. 1 and 2, the operation of each solenoid valve (gaseous fuel supply control solenoid valve 43, air release valve control solenoid valve 53 (53a, 53b), solenoid on-off valve 61) provided in the gaseous fuel supply control mechanism 40, the air release mechanism 50, and the inert gas introduction control mechanism 60 is electrically controlled by each of the following means realized in the control device 70, thereby executing each of the following processes.

[0080] (6-1) Gaseous Fuel Supply Stop Control Means 74 (Gaseous Fuel Supply Stop Processing) When the engine 10 stops in accordance with a predetermined stop processing, the control device 70 activates the gaseous fuel supply stop control means 74 .

[0081] The gaseous fuel supply stop control means 74 controls the operation of the gaseous fuel supply control mechanism 40 to execute a gaseous fuel supply stop process, which stops the supply of gaseous fuel from the gaseous fuel source 20 to the fuel supply passage 22 (22a, 22b).

[0082] In the configuration of the embodiment shown in FIG. 1, when the gas fuel supply stop process is executed, the gas fuel supply stop control means 74 controls the gas fuel supply control electromagnetic valve 43 of the gas fuel supply control mechanism 40 to cut off communication between the nitrogen source 30 and the gas fuel supply valve control circuit 42.

[0083] As a result, the introduction of operating pressure (nitrogen gas) to the gaseous fuel supply valve 41 is stopped, the gaseous fuel supply valve 41 is closed by the force of the return spring, and the supply of hydrogen gas, which is the gaseous fuel, from the gaseous fuel source 20 to the fuel supply path 22 is stopped.

[0084] The gas fuel supply stop control means 74 maintains the operation of the gas fuel supply control mechanism 40 (the position of the gas fuel supply control solenoid valve 43) in a state in which the supply of hydrogen gas to the fuel supply path 22 is stopped until a new command to start the engine 10 is received.

[0085] (6-2) In-supply path fuel discharge control means 75 (in-supply path fuel discharge processing) Simultaneously with the execution of the gas fuel supply stop processing described above, or after the execution of the gas fuel supply stop processing, the control device 70 activates the in-supply path fuel discharge control means 75 to execute an in-supply path fuel discharge processing, which releases the gas fuel remaining in the fuel supply path 22 (22a, 22b) into the atmosphere.

[0086] In this embodiment, the in-supply path fuel discharge control means 75 controls the air release valve control electromagnetic valves 53 (primary side air release valve control electromagnetic valve 53a, secondary side air release valve control electromagnetic valve 53b) provided in the air release mechanism 50 to connect the air release valve control circuit 52 (primary side air release valve control circuit 52a, secondary side air release valve control circuit 52b) with the nitrogen source 30, thereby introducing nitrogen gas as operating pressure into the air release valves 51 (primary side air release valve 51a, secondary side air release valve 51b), thereby opening the air release valves 51 (primary side air release valve 51a, secondary side air release valve 51b) and opening the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) to the atmosphere.

[0087] In addition, the fuel discharge control means 75 in the supply path controls the electromagnetic opening / closing valve 61 that constitutes the inert gas introduction control mechanism 60 to open it, thereby introducing nitrogen gas from the nitrogen source 30 into the fuel supply path 22 (primary side fuel supply path 22 a, secondary side fuel supply path 22 b) via the inert gas introduction path 32.

[0088] As a result, the hydrogen gas, which is the gaseous fuel remaining in the fuel supply path 22 (22a, 22b), is pushed out by the introduced nitrogen gas and discharged to the outside of the apparatus via the air release flow path 54 (54a, 54b), and the gas in the fuel supply path 22 (22a, 22b) is replaced with nitrogen gas.

[0089] When a preset discharge time T1 has elapsed since the start of nitrogen gas introduction, counted by a timer (not shown) provided in the control device 70, the in-supply-path fuel discharge control means 75 operates the air release valve control solenoid valves 53 (primary-side air release valve control solenoid valve 53a, secondary-side air release valve control solenoid valve 53b) provided in the air release mechanism 50 to cut off communication between the air release valve control circuit 52 (primary-side air release valve control circuit 52a, secondary-side air release valve control circuit 52b) and the nitrogen source 30, and also controls the air release valve control circuit 52 By opening the air release valves 51 (primary side air release valve control circuit 52a, secondary side air release valve control circuit 52b) to the atmosphere, the air release valves 51 (primary side air release valve 51a, secondary side air release valve 51b) are closed, and the opening of the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) to the atmosphere is completed, and the electromagnetic opening / closing valve 61, which is the inert gas introduction control mechanism 60, is closed to stop the introduction of nitrogen gas into the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b), and the fuel discharge process within the supply path is completed.

[0090] (6-3) Cranking control means 77 (cranking process) Furthermore, the cranking control means 77 may be configured to be realized in the control device 70 simultaneously with or after the completion of the above-described process of discharging fuel from the supply passage.

[0091] The cranking control means 77 performs a cranking process in which the starter motor 12 of the engine 10 is energized to rotate the engine 10 by the starter motor 12 until a predetermined cranking time T2 has elapsed.

[0092] As a result, the hydrogen gas remaining in the combustion chamber of the engine 10 is discharged outside the aircraft through the exhaust system 13 of the engine 10, and the inert gas filled in the fuel supply passage 22 is drawn into the combustion chamber of the engine and replaced with hydrogen gas, thereby preventing oxidation and hydrogen embrittlement of parts such as the cylinders and pistons of the engine 10.

[0093] (6-4) Other Means The stop condition determination means 71 in FIG. 2 monitors and determines whether the conditions for stopping the engine 10 are met (for example, whether the operator has operated the stop switch) while the engine 10 is running.

[0094] Furthermore, when the stop condition determination means 71 determines that the stop condition is satisfied, the engine stop control means 72 outputs a stop command to the engine 10 (ECU 11 of the engine 10) and executes processing to stop the engine 10.

[0095] Furthermore, the engine stoppage determining means 73 monitors the rotational speed of the engine 10 and determines whether the rotational speed of the engine 10 has become 0 (whether the engine has stopped).

[0096] [Operation of Residual Gaseous Fuel Discharge Device, etc.] The operation of the gaseous fuel engine unit 1 equipped with the residual gaseous fuel discharge device 2 configured as above will be described with reference to FIGS. 3 and 4. FIG.

[0097] While the engine 10 is operating, the stop condition determining means 71 of the control device 70 monitors and determines whether or not the conditions for stopping the engine 10 (stop conditions) are met (S1 in FIG. 3).

[0098] As an example, the stop condition determination means 71 may determine that the above-mentioned stop condition is satisfied when the operation stop switch is operated by the operator, or, if the gas fuel engine unit 1 requires cooling operation when the engine 10 is stopped, may determine that the above-mentioned stop condition is satisfied when the operation stop switch is operated by the operator and the specified cooling operation is completed, and the above-mentioned stop condition can be set in various ways depending on the specifications of the gas fuel engine unit 1.

[0099] If the stop condition is not satisfied (No in S1 of FIG. 3), the stop condition determination means 71 continues to monitor whether the stop condition is satisfied.

[0100] On the other hand, when the stop condition determination means 71 determines that the stop condition is satisfied (Yes in S1 of Figure 3), the engine stop control means 72 outputs a stop command for the engine 10 to the ECU 11 of the engine 10 to execute the stop processing for the engine 10 (S2 in Figure 3 / t1 in Figure 4).

[0101] When the engine stop process is executed, the engine stop determination means 73 monitors the rotation speed of the engine 10 and determines whether the rotation speed of the engine 10 has become 0 (whether the engine has stopped) (S3 in FIG. 3).

[0102] The engine stop determination means 73 continues to monitor the rotation speed until the rotation speed of the engine 10 becomes 0 (loop of No in S3 in Figure 3), and when it is detected that the rotation speed has become 0 and it is determined that the engine 10 has stopped (Yes in S3 in Figure 3 / t2 in Figure 4), the gas fuel supply stop control means 74 and the in-supply path fuel discharge control means 75 perform the following processing.

[0103] When the engine stop determination means 73 determines that the engine 10 has stopped (Yes in S3 in FIG. 3 / t2 in FIG. 4), the gaseous fuel supply stop control means 74 closes the gaseous fuel supply control solenoid valve 43 to stop the introduction of operating pressure (nitrogen gas) to the gaseous fuel supply valve 41 and closes the gaseous fuel supply valve 41, thereby stopping the introduction of gaseous fuel to the fuel supply passage 22 (22a, 22b) (S4 in FIG. 3), and maintains this state until a new command to start the engine 10 is issued.

[0104] Furthermore, when the engine stop determination means 73 determines that the engine 10 has stopped (Yes in S3 in FIG. 3 / t2 in FIG. 4), the in-supply path fuel discharge control means 75 opens the air release valve control electromagnetic valves 53 (53a, 53b) to start introducing operating pressure (nitrogen gas) into the air release valves 51 (51a, 51b) and opens the air release valves 51 (51a, 51b) to open the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) to the atmosphere via the air release flow paths 54 (54a, 54b) (S5 in FIG. 3 / t2 in FIG. 4), and opens the electromagnetic opening / closing valve 61, which is the inert gas introduction control mechanism 60, to start introducing nitrogen gas into the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) (S6 in FIG. 3 / t2 in FIG. 4).

[0105] In this way, with the supply of hydrogen gas to the fuel supply path 22 stopped and with the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) open to the atmosphere via the air release flow path 54 (54a, 54b), nitrogen gas is introduced into the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b). As a result, the hydrogen gas remaining in the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) is pushed out by the nitrogen gas and released into the atmosphere, and the gas in the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) is replaced from hydrogen gas to nitrogen gas, which is an inert gas.

[0106] A timer (not shown) provided in the control device 70 continues counting from the start of the introduction of nitrogen gas (S6 in FIG. 3 / t2 in FIG. 4) until a predetermined discharge time T1 has elapsed (loop of No in S7 in FIG. 3), and when the predetermined discharge time T1 has elapsed (Yes in S7 in FIG. 3 / t3 in FIG. 4), the fuel discharge control means 75 in the supply path ends the fuel discharge process in the supply path.

[0107] This process of discharging fuel from within the supply path is terminated when the fuel discharge control means 75 closes the electromagnetic valves 53 (53a, 53b) for controlling the air release valve to cut off communication between the nitrogen source 30 and the air release valve control circuit 52 (52a, 52b), opens the air release valve control circuit 52 (52a, 52b) to the atmosphere, and closes the air release valves 51 (51a, 51b), thereby completing the opening of the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) to the atmosphere, and closes the electromagnetic opening / closing valve 61, which is the inert gas introduction control mechanism 60, to stop the introduction of nitrogen gas into the fuel supply path 22 (primary side fuel supply path 22a, secondary side fuel supply path 22b) (S8 in FIG. 3 / t3 in FIG. 4).

[0108] Furthermore, when the fuel discharge process within the supply path is completed (t3 in Figure 4), the cranking control means 77 of the control device 70 energizes the starter motor 12 of the engine 10 to rotate the engine using the starter motor 12, thereby executing the cranking process (S9 in Figure 3 / t3-t4 in Figure 4).

[0109] By performing this cranking process, hydrogen gas remaining in the combustion chamber of the engine 10 is discharged outside the aircraft via the exhaust system 13 of the engine 10, and nitrogen gas filled in the fuel supply passage 22 is drawn into the combustion chamber and replaced with hydrogen gas, thereby effectively preventing hydrogen embrittlement from occurring in the cylinders, pistons, etc. of the engine 10.

[0110] The cranking control means 77 continues supplying current to the starter motor 12, and therefore continues the cranking process, until a preset cranking time T2 is counted by the timer (loop of No in S10 in Figure 3), and when the preset cranking time T2 is counted (Yes in S10 in Figure 3), it stops supplying current to the starter motor 12 and ends the cranking process (S11 in Figure 3 / t4 in Figure 4), and the process of discharging residual gaseous fuel is completed (END in Figure 3).

[0111] [Modified example of residual gas fuel discharge device] (Example 2) In the residual gas fuel discharge device 2 of the gas fuel engine unit described above with reference to Figures 1 to 4, the fuel discharge control means 75 in the supply path opens the fuel supply path 22 (22a, 22b) to the atmosphere and introduces nitrogen gas until a predetermined discharge time T1 is counted by a timer, and the cranking control means 77 performs the cranking process of the engine 10 until a predetermined cranking time T2 is counted by the timer.

[0112] In contrast to this, in the configuration (embodiment 2) shown in FIGS. 5 to 8, a hydrogen concentration detector 55 is provided to detect the hydrogen concentration in the air release flow passage 54 that communicates with the fuel supply passage 22 (primary side fuel supply passage 22a, secondary side fuel supply passage 22b), and a hydrogen concentration detector 15 is provided to detect the hydrogen concentration in the exhaust system 13 of the engine 10 (see FIG. 5). When the hydrogen concentration in the air release flow passage 54, and therefore the hydrogen concentration in the fuel supply passage 22 (22a, 22b), becomes less than a predetermined threshold value C1 (for example, a hydrogen concentration less than 4%) (Yes in S7' in FIG. 7 / t3 in FIG. 8), the fuel discharge control in the supply passage is started. When the fuel discharge process within the supply passage by the means 75 (opening the fuel supply passage 22 (22a, 22b) to the atmosphere and introducing nitrogen gas into the fuel supply passage 22 (22a, 22b)) is completed and the hydrogen concentration within the exhaust system 13 of the engine 10 falls below a predetermined threshold value (for example, a hydrogen concentration of less than 4%) (Yes in S10' in FIG. 7 / t4 in FIG. 8), the cranking process (energization of the starter motor 12) by the cranking control means 77 is stopped, and the other configurations are the same as those of the first embodiment described with reference to FIGS. 1 to 4.

[0113] In the illustrated example, the fuel discharge control means 75 terminates the fuel discharge process within the supply path based on the hydrogen concentration within the air release flow path 54 (54a, 54b). However, instead of this configuration, the hydrogen concentration within the fuel supply path 22 may be directly detected, and the fuel discharge process within the supply path may be terminated when it is detected that the hydrogen concentration within the fuel supply path 22 has fallen below a predetermined threshold value C1.

[0114] In the configuration of Example 1 described with reference to Figures 1 to 4, the fuel discharge process within the supply path and the cranking process are terminated at the specified discharge time T1 and the specified cranking time T2. Therefore, once the specified discharge time T1 and the cranking time T2 have elapsed, the process is terminated even if hydrogen gas still remains in the fuel supply path 22 (22a, 2b), the air release flow path 54, the combustion chamber of the engine 10, or the exhaust system 13 of the engine 10. Furthermore, even if the discharge of hydrogen gas from the fuel supply path 22, the air release flow path 54, the engine 10, and the exhaust system 13 of the engine 10 has been completed, the fuel discharge process within the supply path and the cranking process continue unnecessarily until the specified discharge time T1 and the specified cranking time T2 have elapsed.

[0115] In contrast to this, in the configuration of the embodiment (embodiment 2) shown in Figures 5 to 8, hydrogen concentration detectors 55, 15 are provided to detect the hydrogen concentration in the air release flow path 54 and the exhaust system 13 of the engine 10, and the hydrogen concentration in the air release flow path 54 and the exhaust system 13 of the engine 10 is constantly monitored to terminate the residual gaseous fuel discharge process and the cranking process.This means that the fuel discharge process in the supply path and the cranking process will not be terminated when gaseous fuel remains at a concentration exceeding the thresholds C1 and C2, and the fuel discharge process in the supply path and the cranking process will not be continued unnecessarily even after the gaseous fuel concentration falls below the thresholds C1 and C2, so that the residual gaseous fuel can be discharged reliably and efficiently.

[0116] In the above explanation, the configuration has been described in which the hydrogen concentration in the air release flow path 54 or the exhaust system 13 of the engine 10 is measured to terminate the fuel discharge process in the supply path or the cranking process, but it is also possible to measure the nitrogen concentration in the air release flow path 54 or the exhaust system 13 of the engine 10 and terminate the fuel discharge process in the supply path or the cranking process when the nitrogen concentration exceeds 96%, for example.

[0117] Furthermore, in the examples shown in Figures 5 to 8, a configuration has been described in which both the fuel discharge process in the supply path and the cranking process are terminated when the hydrogen concentration becomes less than a predetermined threshold value. However, it is also possible to configure either the fuel discharge process in the supply path or the cranking process to be terminated after a predetermined exhaust time T1 or a predetermined cranking time T2 has elapsed, and to terminate only the other process when the hydrogen concentration becomes less than a predetermined threshold value.

[0118] REFERENCE SIGNS LIST 1 Gaseous fuel engine unit (hydrogen engine unit) 2 Residual gaseous fuel discharge device 10 Engine 11 Engine control unit (ECU) 12 Starter motor 13 Exhaust system (engine) 15 Hydrogen concentration detector 20 Gaseous fuel source (hydrogen source) 22 Fuel supply path (hydrogen gas supply path) 22a Primary side fuel supply path 22b Secondary side fuel supply path 24 Pressure regulator (for gaseous fuel) 30 Inert gas source (nitrogen source) 30a Nitrogen gas cylinder 30b Pressure regulator (for inert gas) 32 Inert gas introduction path (nitrogen gas introduction path) 40 Gaseous fuel supply control mechanism 41 Gaseous fuel supply valve 42 Gaseous fuel supply valve control circuit 43 Gaseous fuel supply control solenoid valve 50 Air release mechanism 50a Primary side air release mechanism 50b Secondary side air release mechanism 51 Air release valve 51a Primary side air release valve 51b Secondary side air release valve 52 Air release valve control circuit 52a Primary side air release valve control circuit 52b Secondary side air release valve control circuit 53 Air release valve control solenoid valve 53a Primary side air release valve control solenoid valve 53b Secondary side air release valve control solenoid valve 54 (54a, 54b) Air release flow path 55 Hydrogen concentration detector 60 Inert gas introduction control mechanism 61 Solenoid on / off valve 70 Control device (electronic control device) 71 Stop condition determination means 72 Engine stop control means 73 Engine stop determination means 74 Gaseous fuel supply stop control means 75 In-supply path fuel discharge control means 77 Cranking control means 110 Engine 117 Supercharger 120 Hydrogen source 122 Hydrogen fuel supply pipe 141 Flow rate adjustment valve 181 Liquid fuel supply unit 185 Hydrogen fuel supply unit 187 Air release valve T1 Discharge time T2 Cranking time C1 Threshold value (of hydrogen concentration in fuel supply passage / air release passage) C2 Threshold value (of hydrogen concentration in the engine exhaust system) TH Threshold value (of pressure in gaseous fuel supply pipe) CV1, CV2, CV3 Check valve

Claims

1. In a gas fuel engine unit including an engine capable of using a gas fuel as a fuel and a fuel supply passage for supplying the gas fuel from a gas fuel source to the engine, an inert gas introduction passage for introducing an inert gas from an inert gas source into the fuel supply passage is provided. After the engine stops, a gas fuel supply stop process for stopping the supply of the gas fuel from the gas fuel source to the fuel supply passage is performed. After the gas fuel supply stop process, a fuel discharge process in the supply passage for discharging the gas fuel remaining in the fuel supply passage to the atmosphere is executed. The fuel discharge process in the supply passage is performed by introducing the inert gas into the fuel supply passage through the inert gas introduction passage with the fuel supply passage open to the atmosphere, thereby pushing out the gas fuel remaining in the fuel supply passage outside the fuel supply passage and replacing it with the inert gas. When a predetermined discharge end condition is satisfied, the opening of the fuel supply passage to the atmosphere is terminated, the introduction of the inert gas into the fuel supply passage is stopped, and the fuel discharge process in the supply passage is terminated. A method for discharging residual gas fuel in a gas fuel engine unit is characterized by the above.

2. After the completion of the fuel discharge process in the supply passage, a cranking process for rotating the engine by a starter motor is performed until a predetermined cranking end condition is satisfied, thereby discharging the gas fuel remaining in the combustion chamber of the engine through the exhaust system of the engine. The method for discharging residual gas fuel in the gas fuel engine unit according to claim 1 is characterized by the above.

3. The method for discharging residual gas fuel in the gas fuel engine unit according to claim 1 is characterized in that the fuel discharge process in the supply passage is terminated with the passage of a predetermined discharge time or a decrease in the gas fuel concentration in the fuel supply passage below a predetermined threshold value as the discharge end condition.

4. The method for discharging residual gas fuel in the gas fuel engine unit according to claim 2 is characterized in that the fuel discharge process in the supply passage is terminated with the passage of a predetermined discharge time or a decrease in the gas fuel concentration in the fuel supply passage below a predetermined threshold value as the discharge end condition.

5. A gas discharge passage for discharging gaseous fuel remaining in the fuel supply passage to the atmosphere is provided in communication with the fuel supply passage. When the concentration of the gaseous fuel in the gas discharge passage drops below the predetermined threshold value, it is determined that the concentration of the gaseous fuel in the fuel supply passage has dropped below the predetermined threshold value. A method for discharging residual gaseous fuel in the gaseous fuel engine unit according to claim 3 or 4.

6. The cranking process is terminated with the passage of a predetermined cranking time or the drop of the concentration of the gaseous fuel in the exhaust system of the engine below a predetermined threshold value as the cranking end condition. A method for discharging residual gaseous fuel in the gaseous fuel engine unit according to claim 2.

7. The cranking process is terminated with the passage of a predetermined cranking time or the drop of the concentration of the gaseous fuel in the exhaust system of the engine below a predetermined threshold value as the cranking end condition. A method for discharging residual gaseous fuel in the gaseous fuel engine unit according to claim 4.

8. A pressure regulator for gaseous fuel is provided in the fuel supply passage. The fuel supply passage on the primary side of the pressure regulator for gaseous fuel is defined as the primary side fuel supply passage, and the fuel supply passage on the secondary side of the pressure regulator for gaseous fuel is defined as the secondary side fuel supply passage. The fuel discharge process in the supply passage is carried out by introducing an inert gas into the primary side fuel supply passage and the secondary side fuel supply passage respectively with the primary side fuel supply passage and the secondary side fuel supply passage open to the atmosphere. The fuel discharge process in the supply passage is terminated by ending the opening of both the primary side fuel supply passage and the secondary side fuel supply passage to the atmosphere and stopping the introduction of the inert gas into both the primary side fuel supply passage and the secondary side fuel supply passage. A method for discharging residual gaseous fuel in the gaseous fuel engine unit according to any one of claims 1 to 4, 6, and 7.

9. In a gas fuel engine unit including an engine capable of using gas fuel as fuel and a fuel supply passage for supplying gas fuel from a gas fuel source to the engine, an inert gas introduction passage communicating between an inert gas source and the fuel supply passage is provided, and a gas fuel supply control mechanism for opening and closing between the gas fuel source and the fuel supply passage, a venting mechanism for starting and stopping the atmospheric release of the fuel supply passage, an inert gas introduction control mechanism for opening and closing between the inert gas source and the fuel supply passage, and a control device comprising an electronic control unit for controlling the operations of the gas fuel supply control mechanism, the venting mechanism, and the inert gas introduction control mechanism are provided. By the control device, after the engine stops, a gas fuel supply stop control means for operating the gas fuel supply control mechanism to cut off the communication between the gas fuel source and the fuel supply passage and stop the supply of gas fuel to the fuel supply passage is executed. After the execution of the gas fuel supply stop process by the gas fuel supply stop control means, a supply passage fuel discharge control means for discharging the gas fuel remaining in the fuel supply passage to the atmosphere is realized. The supply passage fuel discharge control means operates the venting mechanism to open the fuel supply passage to the atmosphere, and operates the inert gas introduction control mechanism to introduce inert gas from the inert gas source into the fuel supply passage to execute the supply passage fuel discharge process. When a predetermined discharge end condition is satisfied, the venting mechanism is operated to end the atmospheric release of the fuel supply passage, and the inert gas introduction control mechanism is operated to stop the introduction of inert gas into the fuel supply passage, thereby ending the supply passage fuel discharge process. A device for discharging residual gas fuel in a gas fuel engine unit is characterized in that it is configured as described above.

10. The gas fuel supply control mechanism is composed of a gas fuel supply valve which is a pneumatic valve for opening and closing between the gas fuel source and the fuel supply passage, a gas fuel supply valve control circuit for introducing inert gas from the inert gas source as an operating pressure to the gas fuel supply valve, and a gas fuel supply control electromagnetic valve for communicating and shutting off between the inert gas source and the gas fuel supply valve control circuit. The purge mechanism is composed of a purge valve which is a pneumatic valve for opening the fuel supply passage to the atmosphere, a purge valve control circuit for introducing inert gas from the inert gas source as an operating pressure to the purge valve, and a purge valve control electromagnetic valve for communicating and shutting off between the inert gas source and the purge valve control circuit. The inert gas introduction control mechanism is composed of an electromagnetic on-off valve provided in the inert gas introduction passage. The gas fuel supply control electromagnetic valve is configured to be operable by the gas fuel supply stop control means of the control device. The purge valve control electromagnetic valve and the electromagnetic on-off valve which is the inert gas introduction control mechanism are configured to be operable by the fuel discharge control means in the supply passage of the control device. A residual gas fuel discharge device in a gas fuel engine unit according to claim 9, characterized in that.

11. An inert gas pressure regulator for adjusting the pressure of the inert gas is provided in the inert gas source. On the secondary side of the inert gas pressure regulator, the inert gas introduction passage is communicated through the electromagnetic on-off valve, the gas fuel supply valve control circuit is communicated through the gas fuel supply control electromagnetic valve, and the purge valve control circuit is communicated through the purge valve control electromagnetic valve. A residual gas fuel discharge device in a gas fuel engine unit according to claim 10, characterized in that.

12. After the completion of the fuel discharge process in the supply passage by the fuel discharge control means in the supply passage, a cranking control means for rotating the starter motor of the engine to perform a cranking process until a predetermined cranking end condition is satisfied is realized by the control device. A residual gas fuel discharge device in a gas fuel engine unit according to any one of claims 9 to 11, characterized in that.

13. The residual gas fuel discharging device in the gaseous fuel engine unit according to any one of claims 9 to 11, wherein the fuel discharging control means in the supply passage ends the fuel discharging process in the supply passage when a predetermined discharging time elapses or when the gaseous fuel concentration in the fuel supply passage drops below a predetermined threshold value as the discharging end condition.

14. A bleed passage for discharging the gaseous fuel remaining in the fuel supply passage to the atmosphere is provided in communication with the fuel supply passage. The fuel discharging control means in the supply passage determines that the gaseous fuel concentration in the fuel supply passage has dropped below the predetermined threshold value when the gaseous fuel concentration in the bleed passage drops below the predetermined threshold value. The residual gas fuel discharging device in the gaseous fuel engine unit according to claim 13 is characterized by this.

15. The residual gas fuel discharging device in the gaseous fuel engine unit according to claim 12, wherein the cranking control means ends the cranking process when a predetermined cranking time elapses or when the gaseous fuel concentration in the exhaust system of the engine drops below a predetermined threshold value as the cranking end condition.

16. A pressure regulator for gaseous fuel is provided in the fuel supply passage. The fuel supply passage on the primary side of the pressure regulator for gaseous fuel is defined as the primary side fuel supply passage, and the fuel supply passage on the secondary side of the pressure regulator for gaseous fuel is defined as the secondary side fuel supply passage. The inert gas introduction passage communicates with each of the primary side fuel supply passage and the secondary side fuel supply passage. The bleed mechanism is provided with a primary side bleed valve for opening the primary side fuel supply passage to the atmosphere and a secondary side bleed valve for opening the secondary side fuel supply passage to the atmosphere as the bleed valves respectively. As the bleed valve control circuit, a primary side bleed valve control circuit for introducing an operating pressure to the primary side bleed valve and a secondary side bleed valve control circuit for introducing an operating pressure to the secondary side bleed valve are provided respectively. As the solenoid valve for bleed valve control, a primary side solenoid valve for bleed valve control for communicating and blocking the communication between the inert gas source and the primary side bleed valve control circuit and a secondary side solenoid valve for bleed valve control for communicating and blocking the communication between the inert gas source and the secondary side bleed valve control circuit are provided respectively. The residual gas fuel discharging device in the gaseous fuel engine unit according to claim 10 or 11 is characterized by this.

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