Exhausting method and exhausting device for residual gas fuel of gas fuel engine unit

Abstract

To exhaust the residual gas fuel in a fuel supply path and an engine after the engine stops.SOLUTION: An inert gas introduction path 32 is provided which introduces an inert gas into a fuel supply path 22 for supplying hydrogen to an engine 10, and a control device 70 consisting of an electronic control device executes supply path internal fuel exhaustion processing for releasing the gas fuel remaining in the fuel supply path 22 to the atmosphere after executing gas fuel supply stop processing to block communication between a gas fuel source 20 and the gas supply path 22 by operating a gas fuel supply control mechanism 40 after the engine 10 stops. The supply path internal fuel exhaustion processing is executed by introducing the inert gas from the inert gas source 30 into the fuel supply path 22 by an inert gas introduction control mechanism 60 with the fuel supply path 22 open to the atmosphere by an exhaustion mechanism 50.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an engine which is an internal combustion engine operated by combustion of a gaseous fuel such as hydrogen, and an engine unit provided with a fuel supply passage for supplying the gaseous fuel to the engine (referred to as a "gaseous fuel engine unit" in the present invention). When the engine is in a stopped state, the present invention relates to a method for discharging residual gaseous fuel so as not to leave the gaseous fuel in the fuel supply passage or in the fuel supply passage and the engine, and a device for discharging the residual gaseous fuel for executing the discharging method.

[0002] In the present invention, the "gaseous fuel engine unit" widely includes those provided with a fuel supply passage for supplying a gaseous fuel such as hydrogen gas to the engine, and in addition to an engine unit provided with a gaseous fuel dedicated engine that can use only gaseous fuel as fuel, any of an engine unit provided with an engine that can selectively use both gaseous fuel and liquid fuel, or an engine that can use a mixture of gaseous fuel and liquid fuel as fuel is also included.

Background Art

[0003] As social interest in environmental issues has increased, the demand for decarbonization has come to be required in all fields. Regarding the fuel used in an engine which is an internal combustion engine, the use of gaseous fuels such as natural gas, which has a lower CO2 emission during combustion compared to petroleum fuels, and hydrogen gas, which does not generate CO2 during combustion, has come to be attracting attention.

[0004] A gaseous fuel engine unit equipped with an engine operated by combustion of such a gaseous fuel is provided with a fuel supply passage for supplying high-pressure gaseous fuel from a gaseous fuel source such as a cylinder filled with gaseous fuel to the engine. However, 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 passes through the stopped engine and gradually leaks into the engine room, so there is a risk of ignition for the leaked gaseous fuel.

[0005] Also, when the gaseous fuel is hydrogen gas, if hydrogen gas remains in the fuel supply passage or the engine, hydrogen atoms with a small atomic size can penetrate into the metal materials such as the pipes provided in the fuel supply passage, the cylinders of the engine, and the pistons, causing "hydrogen embrittlement" that embrittles the materials. Therefore, the occurrence of such hydrogen embrittlement can also be a cause of failure of the gaseous fuel engine unit and accidents associated therewith.

[0006] Therefore, when the engine is stopped, it is desirable to discharge the gaseous fuel remaining in the fuel supply passage and the engine to the outside of the gaseous fuel supply system and the engine, preferably to the outside of the engine room or bonnet that houses the engine.

[0007] Regarding the discharge of such residual fuel, Patent Document 1 cited below discloses that, as shown in FIG. 9, a flow rate adjustment valve 141 is provided between a hydrogen fuel supply pipe 122 that supplies hydrogen fuel to an engine 110 and a hydrogen source 120. By executing a cooling mode operation in which the engine 110 is cooled in a no-load state before the engine 110 stops with the flow rate adjustment valve 141 closed to cut off the supply of fuel from the hydrogen source 120 to the hydrogen fuel supply pipe 122, the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 is consumed. 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 discharged into the engine room via a bleed valve 187.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the engine unit described in the aforementioned Patent Document 1, by executing the cooling mode operation of the engine 110 with the supply of hydrogen fuel from the hydrogen source 120 to the hydrogen fuel supply pipe 122 cut off, it is possible to consume the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 without waste during the cooling mode operation. Subsequently, by discharging the remaining hydrogen fuel, the discharge amount of hydrogen fuel can be reduced as much as possible, and the engine can be operated economically with hydrogen fuel.

[0010] In addition, since the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 during the cooling mode operation can be consumed to reduce the amount of hydrogen fuel in the hydrogen fuel supply pipe 122 as much as possible, even when the gaseous fuel remaining in the hydrogen fuel supply pipe 122 is discharged into the engine room via the blow-off valve 187 later, the concentration of hydrogen fuel in the engine room can be set to a low value less than the hydrogen concentration at which ignition is possible (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 becomes larger and the length becomes longer.

[0012] Therefore, when attempting to consume the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 during the cooling mode operation to less than a predetermined amount, for example, an amount that can make the hydrogen concentration in the engine room less than 4% when discharged into the engine room, the thicker and longer the hydrogen fuel supply pipe 122 is, the longer the cooling mode operation time needs to be, and the lower the pressure (threshold value TH) in the hydrogen fuel supply pipe 122 when the hydrogen fuel supply pipe 122 is opened to the atmosphere needs to be set.

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

[0014] Further, in the configuration described in the embodiment of Patent Document 1, as shown in FIG. 9, an engine 110 that can be operated by the combustion of either liquid fuel such as light oil supplied through a liquid fuel supply unit 181 or hydrogen fuel supplied through a hydrogen fuel supply unit 185 is adopted. As shown in FIG. 10, after the supply of hydrogen fuel to the hydrogen fuel supply pipe 122 is cut off by closing the flow rate adjustment valve 141, until the pressure in the hydrogen fuel supply pipe 122 becomes less than the threshold value TH (t1 - t2 in FIG. 10), the operating state of the engine during cooling mode operation is shifted from operation using hydrogen fuel to operation using liquid fuel by gradually increasing the supply amount of the liquid fuel supplied through the liquid fuel supply unit 181, so that the engine 110 can be operated in a stable state even during cooling mode operation.

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

[0016] Here, the cooling mode operation is to cool the engine 110 in a no-load state. In such a no-load operation, the rotational speed of the engine 110 is generally set to the no-load rotational speed, which is the minimum rotational speed that can prevent abnormal combustion and abnormal vibration in the engine 110.

[0017] However, when the amount and pressure of the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 decrease due to the consumption of hydrogen fuel during the cooling mode operation, even if the hydrogen fuel supply section 185 is opened at a predetermined opening degree corresponding to the no-load rotation speed, the amount of hydrogen fuel introduced into the combustion chamber of the engine 110 gradually decreases. As a result, the rotation speed of the engine 110 decreases to a rotation speed less than the no-load rotation speed, and abnormal combustion or abnormal vibration may occur in the engine 110.

[0018] In particular, when the amount of hydrogen fuel remaining in the hydrogen fuel supply pipe 122 increases, such as when the hydrogen fuel supply pipe 122 is thick and long, the time during which the engine 110 is operated at a rotation speed less than the no-load rotation speed during the cooling mode operation also becomes longer, and the time during which abnormal combustion or abnormal vibration occurs also becomes longer. As a result, failures and damages are likely to occur in the engine 110, devices connected to the engine (for example, working machines such as compressors and generators), couplings connecting the engine 110 and these devices, and the like.

[0019] Moreover, in the configuration described in Patent Document 1, when the pressure in the hydrogen fuel supply pipe 122 drops below a predetermined threshold value TH (t2 in FIG. 10), the bleed valve 187 is opened to open the hydrogen fuel supply pipe 122 to the atmosphere, and the cooling mode operation is continued by the combustion of the liquid fuel supplied from the liquid fuel supply section 181 thereafter (t2 - t3 in FIG. 10). Thus, the compressed air generated by the supercharger 117 passes through the hydrogen fuel supply section 185 and the hydrogen fuel supply pipe 122 and exits through the bleed valve 187, so that the gaseous fuel having a pressure below the threshold value TH remaining in the hydrogen fuel supply pipe 122 can be discharged.

[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 include a liquid fuel supply unit 181, when the relief valve 187 is opened, the residual 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 supercharger 117 stop. Therefore, the hydrogen fuel remaining in the hydrogen fuel supply pipe 122 is discharged through the relief valve 187 until the pressure in the hydrogen fuel supply pipe 122 becomes atmospheric pressure. However, the hydrogen fuel whose pressure has dropped to atmospheric pressure can still remain in the hydrogen fuel supply pipe 122, and there may be a case 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 view of the drawbacks in the above prior art, and not only in a gaseous fuel engine unit provided with a liquid fuel supply path in addition to a gaseous fuel supply path, but also in a gaseous fuel-only combustion engine unit without a liquid fuel supply path, it is possible to discharge the gaseous fuel remaining in the fuel supply path and, if necessary, the gaseous fuel remaining in the engine without causing abnormal combustion, abnormal vibration, etc. in the engine. An object of the present invention is to provide a method and a device for discharging residual gaseous fuel in a gaseous fuel engine unit.

Means for Solving the Problems

[0022] Hereinafter, the means for solving the problems will be described together with the reference numerals used in the embodiments for carrying out the invention. This reference numeral is described for clarifying the correspondence between the description of the claims and the description of the embodiments for carrying out the invention, and needless to say, it is not used restrictively for interpreting the technical scope of the present invention.

[0023] To achieve the above object, a method for discharging residual gaseous fuel in a gaseous fuel engine unit 1 of the present invention is as follows. In a gaseous fuel engine unit 1 including an engine 10 that can use 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. An inert gas introduction passage 32 is provided for introducing the inert gas from the inert gas source 30 into the fuel supply passage 22. After the engine 10 stops, a gaseous fuel supply stop process for stopping the supply of gaseous fuel from the gaseous fuel source 20 to the fuel supply passage 22, After the gaseous fuel supply stop process, an in-supply passage fuel discharge process is executed to discharge the gaseous fuel remaining in the fuel supply passage 22 to the atmosphere. The in-supply passage fuel discharge process is performed by introducing an inert gas into the fuel supply passage 22 through the inert gas introduction passage 32 with the fuel supply passage 22 open to the atmosphere, thereby pushing out the gaseous fuel remaining in the fuel supply passage 22 outside the fuel supply passage 22 and replacing it with the inert gas. At the same time, When a predetermined discharge end condition is satisfied, the atmosphere opening of the fuel supply passage 22 is terminated, the introduction of the inert gas into the fuel supply passage 22 is stopped, and the in-supply passage fuel discharge process is terminated (Claim 1).

[0024] The method for discharging the residual gaseous fuel of the present invention may include a cranking process of rotating the engine 10 by a starter motor 12 after the in-supply passage fuel discharge process is completed, and by performing the cranking process until a predetermined cranking end condition is satisfied, the gaseous fuel remaining in the combustion chamber of the engine 10 is discharged through the exhaust system 13 of the engine 10 (Claim 2).

[0025] The above-described in-supply passage fuel discharge process can be terminated using the elapse of a predetermined discharge time T1 or the decrease of the gaseous fuel concentration in the fuel supply passage 22 below a predetermined threshold value C1 as the discharge end condition (Claims 3, 4).

[0026] In this case, in a configuration where a bleed passage 54 for discharging the gaseous fuel remaining in the fuel supply passage 22 to the atmosphere is provided in communication with the fuel supply passage 22, when the gaseous fuel concentration in the bleed passage 54 decreases below the predetermined threshold value C1, it may be determined that the gaseous fuel concentration in the fuel supply passage 22 has decreased below the predetermined threshold value C1 (Claim 5).

[0027] Further, the cranking process described above may be terminated when a predetermined cranking time T2 elapses, or when the gas fuel concentration in the exhaust system 13 of the engine 10 drops below a predetermined threshold value C2, which may be used as the cranking end condition described above (Claims 6 and 7).

[0028] Furthermore, in a configuration where a gas fuel pressure regulator 24 is provided in the fuel supply passage 22, and the fuel supply passage 22 on the primary side of the gas fuel pressure regulator 24 is a primary side fuel supply passage 22a, and the fuel supply passage 22 on the secondary side of the gas fuel pressure regulator 24 is a secondary side fuel supply passage 22b, the fuel discharge process in the supply passage is performed by introducing an inert gas into the primary side fuel supply passage 22a and the secondary side fuel supply passage 22b, respectively, with the primary side fuel supply passage 22a and the secondary side fuel supply passage 22b being open to the atmosphere, and the fuel discharge process in the supply passage can be terminated by ending the atmospheric release of both the primary side fuel supply passage 22a and the secondary side fuel supply passage 22b and stopping the introduction of the inert gas into both the primary side fuel supply passage 22a and the secondary side fuel supply passage 22b (Claim 8).

[0029] In addition, the residual gas fuel discharge device in the gas fuel engine unit of the present invention is in a gas fuel engine unit 1 including an engine 10 capable of using gas fuel as fuel and a fuel supply passage 22 for supplying gas fuel from a gas fuel source 20 to the engine 10, an inert gas introduction passage 32 communicating between an inert gas source 30 and the fuel supply passage 22 is provided, a gas fuel supply control mechanism 40 for opening and closing between the gas fuel source 20 and the fuel supply passage 22 is provided, a deflation mechanism 50 for starting and stopping the atmospheric release of the fuel supply passage 22 is provided, an inert gas introduction control mechanism 60 for opening and closing between the inert gas source 30 and the fuel supply passage 22 is provided, A control device 70 comprising an electronic control unit is provided to control the operations of the gaseous fuel supply control mechanism 40, the air bleeding mechanism 50, and the inert gas introduction control mechanism 60. By the control device 70, After the engine 10 stops, a gaseous fuel supply stop control means 74 is provided to execute a gaseous fuel supply stop process of operating the gaseous fuel supply control mechanism 40 to cut off the communication between the gaseous fuel source 20 and the gaseous supply passage 22 and stop the supply of gaseous fuel to the fuel supply passage 22. After the execution of the gaseous fuel supply stop process by the gaseous fuel supply stop control means 74, a fuel discharge control means 75 in the supply passage is realized to execute a fuel discharge process in the supply passage for discharging the gaseous fuel remaining in the fuel supply passage 22 to the atmosphere. The fuel discharge control means 75 in the supply passage is configured to operate the air bleeding mechanism 50 to open the fuel supply passage 22 to the atmosphere, and operate the inert gas introduction control mechanism 60 to introduce the inert gas from the inert gas source 30 into the fuel supply passage 22 to execute the fuel discharge process in the supply passage, and when a predetermined discharge end condition is satisfied, operate the air bleeding mechanism 50 to end the opening of the fuel supply passage 22 to the atmosphere, and operate the inert gas introduction control mechanism 60 to stop the introduction of the inert gas into the fuel supply passage 22, thereby ending the fuel discharge process in the supply passage (Claim 9).

[0030] In the residual gaseous fuel discharge device 2 having the above configuration, The gaseous fuel supply control mechanism 40 is composed of a gaseous fuel supply valve 41 formed of a pneumatic valve that opens and closes between the gaseous fuel source 20 and the fuel supply passage 22, a gaseous fuel supply valve control circuit 42 that introduces the 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 communicates and cuts off between the inert gas source 30 and the gaseous fuel supply valve control circuit 42. The bleed mechanism 50 (50a, 50b) is composed of a bleed valve 51 (51a, 51b) which is an air-operated valve that opens the fuel supply passage 22 (22a, 22b) to the atmosphere, a bleed valve control circuit 52 (52a, 52b) that introduces inert gas from the inert gas source 30 as an operating pressure to the bleed valve 51 (51a, 51b), and a solenoid valve 53 (53a, 53b) for bleed valve control that performs communication and cutoff between the inert gas source 30 and the bleed valve control circuit 52 (52a, 52b). At the same time, The inert gas introduction control mechanism 60 is composed of an electromagnetic on-off valve 61 provided in the inert gas introduction passage 32, The solenoid valve 43 for gaseous fuel supply control is configured to be operable by the gaseous fuel supply stop control means 74 of the control device 70, and The solenoid valve 53 (53a, 53b) for bleed valve control and the electromagnetic on-off 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 passage of the control device 70 (Claim 10).

[0031] In the residual gaseous fuel discharge device 2 having the above configuration, an inert gas pressure regulator 30b for adjusting the pressure of the inert gas is provided in the inert gas source 30, On the secondary side of the inert gas pressure regulator 30b, the inert gas introduction passage 32 via the electromagnetic on-off valve 61, the gaseous fuel supply valve control circuit 42 via the solenoid valve 43 for gaseous fuel supply control, and the bleed valve control circuit 52 (52a, 52b) via the solenoid valve 53 (53a, 53b) for bleed valve control may be respectively communicated (Claim 11).

[0032] Further, the residual gaseous fuel discharge device 2 of the present invention may be such that the control device 70 realizes cranking control means 77 that executes a cranking process of rotating the starter motor 12 of the engine 10 until a predetermined cranking end condition is satisfied after the completion of the fuel discharge process in the supply passage by the fuel discharge control means 75 in the supply passage (Claim 12).

[0033] The fuel discharge control means 75 in the supply passage is configured to end the fuel discharge process in the supply passage when a predetermined discharge time T1 elapses or when the concentration of gaseous fuel in the fuel supply passage 22 drops below a predetermined threshold value C1 (Claim 13).

[0034] In this case, in a configuration where a purge passage 54 for discharging the gaseous fuel remaining in the fuel supply passage 22 to the atmosphere is provided in communication with the fuel supply passage 22, the fuel discharge control means 75 in the supply passage may be configured to determine that the concentration of gaseous fuel in the fuel supply passage 22 has dropped below the predetermined threshold value C1 when the concentration of gaseous fuel in the purge passage 54 drops below the predetermined threshold value C1 (Claim 14).

[0035] Also, the cranking control means 77 is configured to end the cranking process when a predetermined cranking time T2 elapses or when the concentration of gaseous fuel in the exhaust system 13 of the engine drops below a predetermined threshold value C2 (Claim 15).

[0036] Furthermore, in a configuration where a pressure regulator 24 for gaseous fuel is provided in the fuel supply passage 22, the fuel supply passage 22 on the primary side of the pressure regulator 24 for gaseous fuel is defined as a primary-side fuel supply passage 22a, and the fuel supply passage 22 on the secondary side of the pressure regulator 24 for gaseous fuel is defined as a secondary-side fuel supply passage 22b, the inert gas introduction passage 32 communicates with each of the primary-side fuel supply passage 22a and the secondary-side fuel supply passage 22b, the purge mechanism 50 is provided with a primary-side purge valve 51a that opens the primary-side fuel supply passage 22a to the atmosphere and a secondary-side purge valve 51b that opens the secondary-side fuel supply passage 22b to the atmosphere, respectively, the purge valve control circuit 52 is provided with a primary-side purge valve control circuit 52a that introduces an operating pressure to the primary-side purge valve 51a and a secondary-side purge valve control circuit 52b that introduces an operating pressure to the secondary-side purge valve 51b, respectively, and As the purge valve control electromagnetic valve 53, a primary purge valve control electromagnetic valve 53a that communicates and shuts off between the inert gas source 30 and the primary side purge valve control circuit 52a, and a secondary purge valve control electromagnetic valve 53b that communicates and shuts off between the inert gas source 30 and the secondary side purge valve control circuit 52b may be provided respectively (Claim 16).

Advantages of the Invention

[0037] According to the method and device for discharging residual gaseous fuel in the gaseous fuel engine unit 1 of the present invention described above, after the engine 10 stops, the gaseous fuel remaining in the fuel supply passage 22 is discharged, and the fuel supply passage 22 is filled with an inert gas such as nitrogen gas by replacing it with the gaseous fuel. Thus, it is possible to prevent the gaseous fuel in the fuel supply passage 22 from leaking into the engine room through the stopped engine 10 or the like, and it is possible to preferably prevent hydrogen embrittlement and oxidation from occurring in the metal pipes or the like provided in the fuel supply passage 22.

[0038] Moreover, in the configuration of the present invention, after the engine 10 is stopped, the inert gas from the inert gas source 30 is introduced to discharge the fuel remaining in the fuel supply passage 22. Therefore, whether it 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 combustion engine unit, there is no concern that abnormal combustion, abnormal vibration, and associated failures may occur in the engine 10 when removing the gaseous fuel remaining in the fuel supply passage, as in the engine unit introduced as Patent Document 1 above.

[0039] Furthermore, in the configuration of the present invention, after replacing the gaseous fuel in the fuel supply passage 22 with an inert gas, by stopping the atmospheric release of the fuel supply passage 22 and the introduction of the inert gas, the inert gas can be sealed in the fuel supply passage 22.

[0040] In a configuration where the starter motor of the engine is operated for cranking after replacing the residual gaseous fuel in the fuel supply passage 22 with an inert gas, the gaseous fuel remaining in the combustion chamber of the engine 10 can be discharged to the outside of the engine through the exhaust system 13 of the engine 10 and replaced with the inert gas in the fuel supply passage 22 sucked into the combustion chamber. As a result, oxidation of the cylinders and pistons of the engine can be prevented, and even when the gaseous fuel is hydrogen gas, hydrogen embrittlement can be prevented from occurring.

[0041] The above-described in-fuel supply passage fuel discharge process and cranking process may end after the elapse of a predetermined discharge time T1 and cranking time T2. In this case, simplification of the device configuration and control method becomes possible. However, there are demerits such that the process may end before the gaseous fuel remaining in the fuel supply passage 22 and the engine 10 is completely discharged, or the process may be continued unnecessarily until the predetermined discharge time T1 and cranking time T2 elapse even if the discharge of the residual gaseous fuel is completed.

[0042] On the other hand, in a configuration where the discharge process of the residual gaseous fuel ends when the gaseous fuel concentrations in the fuel supply passage 22 and the exhaust system 13 of the engine 10 become less than predetermined threshold values C1 and C2, although additional sensors for detecting the concentration of the gaseous fuel are required, there is a merit that the discharge of the residual gaseous fuel can be performed reliably and efficiently.

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

[0044] In the residual gas fuel discharge device 2 of the present invention, the on-off valves [gas fuel supply valve 41, bleed valve 51 (51a, 51b)] that open and close the flow path through which the gaseous fuel, which is a combustible gas, passes are made into pneumatic valves that operate by introducing an inert gas. While preventing explosion, electromagnetic valves [gas fuel supply control electromagnetic valve 43, bleed valve control electromagnetic valve 53 (53a, 53b)] are adopted as control valves for controlling the introduction and stop of the inert gas to these pneumatic valves [gas fuel supply valve 41, bleed valve 51 (51a, 51b)]. As a result, the complicated opening and closing operations of each part can be automatically controlled by the control device 70.

Brief Description of the Drawings

[0045]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

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

[0047] In the following description, the case of using hydrogen gas as the gas fuel is taken as an example for explanation. However, the application target of the present invention is not limited to the gas fuel engine unit (hydrogen engine unit) using hydrogen gas as the fuel, and it is also applicable to the gas fuel engine unit using other known gas fuels such as natural gas as the fuel.

[0048] Also, in the following description, an example of using nitrogen gas as the inert gas will be described. However, the available inert gas is not limited to nitrogen gas, and other known inert gases such as argon gas can also be used.

[0049] 〔Overall Configuration of Gas Fuel Engine Unit〕 The overall configuration of the gas fuel engine unit (hydrogen engine unit) equipped with the residual gas fuel discharge device of the present invention is shown in FIG. 1.

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

[0051] In this embodiment, an example is shown in which the aforementioned engine 10 is configured as a hydrogen dedicated combustion engine that operates using only hydrogen gas as fuel. However, in the configuration of the gaseous fuel engine unit 1, a liquid fuel supply path (not shown) for supplying liquid fuels such as light oil and gasoline to the engine 10 is provided, and the present invention can also be applied to a gaseous fuel engine unit that is capable of selectively supplying hydrogen fuel and liquid fuel, or simultaneously supplying hydrogen fuel and liquid fuel for operation.

[0052] In the illustrated example, the aforementioned gaseous fuel source 20 is constituted by a hydrogen gas cylinder. However, instead of this configuration, like the prior art described with reference to FIG. 9, a tank filled with liquefied hydrogen may be used as the hydrogen source. In this case, together with the liquefied hydrogen tank, a vaporizer for vaporizing the liquefied hydrogen to obtain hydrogen gas may be included in the configuration of the gaseous fuel source 20.

[0053] The aforementioned gaseous fuel source 20 is communicated with 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 communication and cutoff between the gaseous fuel source 20 and the fuel supply path 22 are controlled by opening and closing the gaseous fuel supply valve 41, and the check valve CV1 prevents the gas in the fuel supply path 22 from flowing into the gaseous fuel source 20 side.

[0054] In the embodiment shown in FIG. 1, a pressure regulator 24 for gaseous fuel that adjusts the pressure of hydrogen gas to a predetermined pressure is provided at an intermediate position of the aforementioned fuel supply path 22. However, this pressure regulator 24 for gaseous fuel may be provided at a position closer to the gaseous fuel source 20, and its arrangement is not limited to the illustrated position.

[0055] Also, when pressure adjusting means such as a pressure regulator is provided in the gaseous fuel source 20, the installation of the pressure regulator 24 for the fuel supply path 22 can be omitted.

[0056] An engine 10 that receives the supply of gaseous fuel via a fuel supply passage 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. Further, a control device 70 composed of an electronic control device such as a microcontroller provided in the gaseous fuel engine unit 1 is configured to be able to start, stop, and control the speed of the engine 10 and the like.

[0057] Moreover, reference numeral 13 in FIG. 1 denotes an exhaust system of the engine constituted by an exhaust pipe, a muffler, etc. (all not shown), which discharges the gas generated when hydrogen gas is burned in the combustion chamber of the engine 10 to the outside of the machine as exhaust gas.

[0058] 〔Residual Gas Fuel Discharge Device〕(Example 1) (1) Overall Configuration In the gaseous fuel engine unit 1 configured as described above, a residual gas fuel discharge device 2 is provided to discharge the hydrogen gas remaining in the fuel supply passage 22 when the engine 10 is stopped, or the hydrogen gas remaining in the fuel supply passage 22 and the hydrogen gas remaining in the engine 10 to the outside of the machine, and to replace the gas in the fuel supply passage 22 and the engine 10 with nitrogen gas.

[0059] This residual gas fuel discharge device 2 is composed of an inert gas introduction passage 32 for introducing an inert gas (nitrogen gas) from an inert gas source (nitrogen source) 30 into the fuel supply passage 22, a gaseous fuel supply control mechanism 40 for opening and closing between the hydrogen source 20 and the fuel supply passage 22 to control the start and stop of the introduction of hydrogen gas into the fuel supply passage 22, a venting mechanism 50 for controlling the start and stop of the atmospheric release of the fuel supply passage 22, an inert gas introduction control mechanism 60 for controlling the communication and interruption of the inert gas introduction passage 32 with respect to the inert gas source 30, and a control device 70 for controlling these operations.

[0060] (2) Inert Gas Introduction Passage 32 The inert gas introduction passage 32 is a passage for introducing an inert gas from the inert gas source 30 into the fuel supply passage 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. The inert gas introduction passage 32 is communicated with the secondary side of the nitrogen gas pressure regulator 30b via an electromagnetic on-off valve 61.

[0062] In the illustrated configuration in which a gas fuel pressure regulator 24 is provided in the fuel supply passage 22, the secondary side of the inert gas introduction passage 32 is branched into two branches. One of the branch passages is communicated with the primary side fuel supply passage 22a, which is the fuel supply passage 22 on the primary side of the gas fuel pressure regulator 24, via a check valve CV2, and the other of the branch passages is communicated with the secondary side fuel supply passage 22b, which is the fuel supply passage 22 on the secondary side of the gas fuel pressure regulator 24, via a check valve CV3.

[0063] By communicating the inert gas introduction passage 32 with the fuel supply passage 22 (22a, 22b) via the check valves CV2 and CV3 in this way, the hydrogen gas in the fuel supply passage 22 (22a, 22b) is prevented from flowing into the inert gas introduction passage 32 side.

[0064] (3) Gas fuel supply control mechanism 40 Reference numeral 40 in FIG. 1 is a gas fuel supply control mechanism. This gas fuel supply control mechanism 40 communicates or shuts off between the gas fuel source 20 and the fuel supply passage 22, and controls the start and stop of the supply of hydrogen gas to the fuel supply passage 22.

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

[0066] Thus, for the gas fuel supply valve 41 that controls the opening and closing of the flow path of gaseous fuel, which is a flammable gas, an air-operated valve that operates using an inert gas as the operating pressure is adopted instead of an electromagnetic valve to achieve explosion prevention. On the other hand, for the electromagnetic valve 43 for gas fuel supply control that opens and closes the flow path of the inert gas that does not require explosion prevention, an electromagnetic valve is adopted to facilitate electrical control by the control device 70 described later.

[0067] By providing the gas fuel supply control mechanism 40 with the above configuration, when the electromagnetic valve 43 for gas fuel supply control is operated to connect the inert gas source 30 and the gas fuel supply valve control circuit 42, the inert gas from the inert gas source 30 is introduced as the operating pressure to the gas fuel supply valve 41, causing the gas fuel supply valve 41 to open and introducing hydrogen gas, which is gaseous fuel, to the fuel supply path 22.

[0068] On the other hand, when the electromagnetic valve 43 for gas fuel supply control is operated to cut off the communication between the inert gas source 30 and the gas fuel supply valve control circuit 42 and to open the gas fuel supply valve control circuit 42 to the atmosphere, the introduction of the inert gas as the operating pressure to the gas fuel supply valve 41 is stopped, and the gas fuel supply valve 41 closes by the biasing force of the return spring, so that the introduction of hydrogen gas to the fuel supply path 22 can be stopped.

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

[0070] For the inert gas introduction control mechanism 60 that controls the opening and closing of the flow path of the inert gas, there is no need for explosion prevention. In the illustrated embodiment, an electromagnetic on-off valve (two-way electromagnetic valve) 61 provided between the inert gas source 30 and the inert gas introduction path 32 is provided as the inert gas introduction control mechanism 60, and the introduction of nitrogen gas to the fuel supply path 22 (22a, 22b) via the inert gas introduction path 32 can be started and stopped by opening and closing the electromagnetic on-off valve 61.

[0071] (5) Bleeding mechanism 50 The bleeding mechanism 50 controls the start and stop of the atmospheric venting of the fuel supply passage 22 (22a, 22b).

[0072] In the embodiment shown in FIG. 1, bleed passages 54a and 54b branched from the primary-side fuel supply passage 22a and the secondary-side fuel supply passage 22b, respectively, are provided on the secondary side with respect to the communication position of the inert gas introduction passage 32, and the bleed passages 54a and 54b are extended outside the machine.

[0073] Then, by controlling the opening and closing of each of the bleed passages 54a and 54b by the bleeding mechanism 50 (primary-side bleeding mechanism 50a, secondary-side bleeding mechanism 50b), the atmospheric venting of the fuel supply passage 22 (primary-side fuel supply passage 22a, secondary-side fuel supply passage 22b) can be started or stopped.

[0074] The opening and closing of the bleed passages 54a and 54b through which hydrogen, which is a combustible gas, can flow is performed by bleed valves 51 (primary-side bleed valve 51a, secondary-side bleed valve 51b) constituted by air-operated valves that operate using nitrogen gas introduced from an inert gas source as the operating pressure. A bleed valve control circuit 52 (primary-side bleed valve control circuit 52a, secondary-side bleed valve control circuit 52b) that introduces nitrogen gas from the nitrogen source 30 as the operating pressure to the bleed valves 51 (primary-side bleed valve 51a, secondary-side bleed valve 51b), and a bleed valve control electromagnetic valve 53 (primary-side bleed valve control electromagnetic valve 53a, secondary-side bleed valve control electromagnetic valve 53b) composed of a three-way solenoid valve that communicates the bleed valve control circuit 52 (primary-side bleed valve control circuit 52a, secondary-side bleed valve control circuit 52b) with the nitrogen source 30 or vents to the atmosphere are provided, thereby constituting the aforementioned bleeding mechanism 50 (primary-side bleeding mechanism 50a, secondary-side bleeding mechanism 50b).

[0075] Thereby, when the bleed valve control electromagnetic valve 53 (53a, 53b) communicates the bleed valve control circuit 52 (52a, 52b) with the nitrogen source 30, the operating pressure (nitrogen gas) is introduced to the bleed valves 51 (51a, 51b), and the bleed valves 51 (51a, 51b) open, thereby starting the atmospheric venting of the fuel supply passage 22 (22a, 22b).

[0076] On the one hand, when the exhaust valve control solenoid valve 53 (53a, 53b) shuts off the communication between the exhaust valve control circuit 52 (52a, 52b) and the nitrogen source 30 and vents the exhaust valve control circuit 52 (52a, 52b) to the atmosphere, the exhaust valve 51 (51a, 51b) closes by the biasing force of the return spring due to the stop of the introduction of the operating pressure (nitrogen gas), thereby stopping the venting of the fuel supply passage 22 (22a, 22b) to the atmosphere.

[0077] In the illustrated example, the primary exhaust valve 51a and the secondary exhaust valve 51b are respectively provided in the exhaust passages 54a and 54b, and the primary exhaust valve control solenoid valve 53a and the secondary exhaust valve control solenoid valve 53b for controlling the start and stop of the introduction of the inert gas to the primary exhaust valve 51a and the secondary exhaust valve 51b are respectively provided. However, instead of this configuration, for example, the start and stop of the introduction of the inert gas to both the primary exhaust valve 51a and the secondary exhaust valve 51b may be controlled by a single exhaust valve control solenoid valve, or a single exhaust valve may be provided on the secondary side of the confluence position of the exhaust passages 54a and 54b, and a single exhaust valve control solenoid valve for controlling the start and stop of the introduction of the inert gas to this exhaust valve may be provided. As long as it is a configuration capable of controlling the start and stop of the venting of the primary fuel supply passage 22a and the secondary fuel supply passage 22b to the atmosphere, the configuration of the exhaust mechanism 50 is not limited to the illustrated configuration.

[0078] (6) Control device 70 The control device 70 is constituted by an electronic control device such as a microcontroller. In addition to controlling the operation of the engine 10 described above, by executing a pre-stored program, each means shown in FIG. 2 in the control device 70 is realized, so that the operations of the gas fuel supply control mechanism 40, the exhaust mechanism 50, and the inert gas introduction control mechanism 60 described above are controlled.

[0079] In the embodiments shown in FIGS. 1 and 2, the operations of the electromagnetic valves provided in the above-described gaseous fuel supply control mechanism 40, purge mechanism 50, and inert gas introduction control mechanism 60 (gaseous fuel supply control electromagnetic valve 43, purge valve control electromagnetic valve 53 (53a, 53b), electromagnetic on-off valve 61) are electrically controlled by the following means realized in the control device 70, and the following processes are executed.

[0080] (6-1) Gaseous fuel supply stop control means 74 (gaseous fuel supply stop process) When the engine 10 stops according to a predetermined stop process, the control device 70 activates the gaseous fuel supply stop control means 74.

[0081] This gaseous fuel supply stop control means 74 executes a gaseous fuel supply stop process of stopping the supply of gaseous fuel from the gaseous fuel source 20 to the fuel supply passages 22 (22a, 22b) by controlling the operation of the gaseous fuel supply control mechanism 40.

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

[0083] Thereby, the introduction of the operating pressure (nitrogen gas) to the gaseous fuel supply valve 41 stops, the gaseous fuel supply valve 41 closes by the biasing 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 passage 22, stops.

[0084] The gaseous fuel supply stop control means 74 maintains the operation (the position of the gaseous fuel supply control electromagnetic valve 43) of the gaseous fuel supply control mechanism 40 in a state where the supply of hydrogen gas to the fuel supply passage 22 is stopped until a new start command for the engine 10 is given.

[0085] (6-2) Fuel discharge control means 75 in the supply passage (fuel discharge process in the supply passage) Simultaneously with the execution of the above-described gas fuel supply stop process or after the execution of the gas fuel supply stop process, the control device 70 activates the in-line fuel discharge control means 75 to execute an in-line fuel discharge process of discharging the gaseous fuel remaining in the fuel supply line 22 (22a, 22b) to the atmosphere.

[0086] In this embodiment, the in-line fuel discharge control means 75 controls the solenoid valves 53 (primary-side bleed valve control solenoid valve 53a, secondary-side bleed valve control solenoid valve 53b) provided in the bleed mechanism 50 to communicate the bleed valve control circuit 52 (primary-side bleed valve control circuit 52a, secondary-side bleed valve control circuit 52b) with the nitrogen source 30, thereby introducing nitrogen gas as an operating pressure to the bleed valves 51 (primary-side bleed valve 51a, secondary-side bleed valve 51b) to open the bleed valves 51 (primary-side bleed valve 51a, secondary-side bleed valve 51b) and open the fuel supply line 22 (primary-side fuel supply line 22a, secondary-side fuel supply line 22b) to the atmosphere.

[0087] Also, the in-line fuel discharge control means 75 controls the electromagnetic on-off valve 61 constituting the inert gas introduction control mechanism 60 to open it, thereby introducing nitrogen gas from the nitrogen source 30 into the fuel supply line 22 (primary-side fuel supply line 22a, secondary-side fuel supply line 22b) via the inert gas introduction line 32.

[0088] Thereby, the hydrogen gas, which is the gaseous fuel remaining in the fuel supply line 22 (22a, 22b), is pushed out by the introduced nitrogen gas and discharged outside the machine through the bleed flow path 54 (54a, 54b), and at the same time, the gas in the fuel supply line 22 (22a, 22b) is replaced with nitrogen gas.

[0089] When the passage of a preset predetermined discharge time T1 from the start of nitrogen gas introduction is counted by a timer (not shown) provided in the control device 70, the fuel discharge control means 75 in the supply passage operates the solenoid valves 53 (primary side bleed valve control solenoid valve 53a, secondary side bleed valve control solenoid valve 53b) provided in the bleed mechanism 50 to cut off the communication between the bleed valve control circuit 52 (primary side bleed valve control circuit 52a, secondary side bleed valve control circuit 52b) and the nitrogen source 30 and open the bleed valve control circuit 52 (primary side bleed valve control circuit 52a, secondary side bleed valve control circuit 52b) to the atmosphere, thereby closing the bleed valves 51 (primary side bleed valve 51a, secondary side bleed valve 51b) to end the atmosphere opening of the fuel supply passage 22 (primary side fuel supply passage 22a, secondary side fuel supply passage 22b). At the same time, the electromagnetic on-off valve 61 which is the inert gas introduction control mechanism 60 is closed to stop the introduction of nitrogen gas into the fuel supply passage 22 (primary side fuel supply passage 22a, secondary side fuel supply passage 22b), and the fuel discharge process in the supply passage is ended.

[0090] (6-3) Cranking control means 77 (cranking process) Furthermore, it may be configured such that the cranking control means 77 is realized in the control device 70 simultaneously with or after the end of the fuel discharge process in the supply passage described above.

[0091] This cranking control means 77 performs a cranking process of rotating the engine 10 by the starter motor 12 by energizing the starter motor 12 of the engine 10 until a predetermined cranking time T2 elapses.

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

[0093] (6-4) Other means Incidentally, during the operation of the engine 10, the stop condition determination means 71 in FIG. 2 monitors and determines whether or not the conditions for stopping the engine 10 are satisfied (for example, whether or not the stop switch has been operated by the operator).

[0094] Further, 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 (the ECU 11 of the engine 10) and executes a process to stop the engine 10.

[0095] Furthermore, the engine stop determination means 73 monitors the rotational speed of the engine 10 and determines whether or not the rotational speed of the engine 10 has become zero (whether or not the engine has stopped).

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

[0097] During the operation of the engine 10, the stop condition determination means 71 of the control device 70 monitors and determines whether or not the conditions (stop conditions) for stopping the engine 10 are satisfied (S1 in FIG. 3).

[0098] As an example, the stop condition determination means 71 may determine that the above-described stop condition is satisfied when the operation stop switch is operated by the operator. Also, when the gaseous fuel engine unit 1 requires a cooling operation when the engine 10 stops, it may be determined that the above-described stop condition is satisfied when the operation stop switch is operated by the operator and a predetermined cooling operation is completed. The above-described stop conditions can be variously set according to the specifications of the gaseous fuel engine unit 1.

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

[0100] On the one hand, when the stop condition determination means 71 determines that the stop condition is satisfied (Yes in S1 of FIG. 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 process of the engine 10 (S2 in FIG. 3 / t1 in FIG. 4).

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

[0102] The monitoring of the rotational speed by the engine stop determination means 73 continues until the rotational speed of the engine 10 becomes 0 (loop of No in S3 of FIG. 3). When it is detected that the rotational speed has become 0 and it is determined that the engine 10 has stopped (Yes in S3 of FIG. 3 / t2 in FIG. 4), the following processes are performed by the gaseous fuel supply stop control means 74 and the in-supply-path fuel discharge control means 75.

[0103] When the engine stop determination means 73 determines that the engine 10 has stopped (Yes in S3 of FIG. 3 / t2 in FIG. 4), the gaseous fuel supply stop control means 74 closes the electromagnetic valve 43 for gaseous fuel supply to stop the introduction of the 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 path 22 (22a, 22b) (S4 in FIG. 3), and maintains this state until a new start command for the engine 10 is given.

[0104] When the engine stop determination means 73 determines that the engine 10 has stopped (Yes in S3 of FIG. 3 / t2 in FIG. 4), the fuel discharge control means 75 in the supply passage opens the solenoid valve 53 (53a, 53b) for wastegate control to start introducing the operating pressure (nitrogen gas) to the wastegate valve 51 (51a, 51b) and opens the wastegate valve 51 (51a, 51b), thereby opening the fuel supply passage 22 (primary fuel supply passage 22a, secondary fuel supply passage 22b) to the atmosphere through the bleed passage 54 (54a, 54b) (S5 in FIG. 3 / t2 in FIG. 4). At the same time, the electromagnetic on-off valve 61, which is the inert gas introduction control mechanism 60, is opened to start introducing nitrogen gas into the fuel supply passage 22 (primary fuel supply passage 22a, secondary fuel supply passage 22b) (S6 in FIG. 3 / t2 in FIG. 4).

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

[0106] A timer (not shown) provided in the control device 70 continues to count until a predetermined discharge time T1 has elapsed since the start of nitrogen gas introduction (S6 in FIG. 3 / t2 in FIG. 4) (loop of No in S7 of FIG. 3). When the elapse of the predetermined discharge time T1 is counted (Yes in S7 of FIG. 3 / t3 in FIG. 4), the fuel discharge control means 75 in the supply passage ends the fuel discharge process in the supply passage.

[0107] The end of the fuel discharge process in this supply passage is carried out by the fuel discharge control means 75 in the supply passage closing the solenoid valve 53 (53a, 53b) for controlling the bleed valve to cut off the communication between the nitrogen source 30 and the bleed valve control circuit 52 (52a, 52b), and by opening the bleed valve control circuit 52 (52a, 52b) to the atmosphere to close the bleed valve 51 (51a, 51b). This ends the opening of the fuel supply passage 22 (primary fuel supply passage 22a, secondary fuel supply passage 22b) to the atmosphere, and also stops the introduction of nitrogen gas into the fuel supply passage 22 (primary fuel supply passage 22a, secondary fuel supply passage 22b) by closing the electromagnetic on-off valve 61 which is the inert gas introduction control mechanism 60 (S8 in Fig. 3 / t3 in Fig. 4).

[0108] Also, when the fuel discharge process in the supply passage ends (t3 in Fig. 4), the cranking control means 77 of the control device 70 energizes the starter motor 12 of the engine 10 to rotate the engine by the starter motor 12, and executes a cranking process (S9 in Fig. 3 / t3 - t4 in Fig. 4).

[0109] By executing this cranking process, the hydrogen gas remaining in the combustion chamber of the engine 10 is discharged outside the engine through the exhaust system 13 of the engine 10, and the nitrogen gas filled in the fuel supply passage 22 is sucked into the combustion chamber and replaced with hydrogen gas, so that the occurrence of hydrogen embrittlement of the cylinder, piston, etc. of the engine 10 can be suitably prevented.

[0110] The cranking control means 77 continues to energize the starter motor 12 until a preset predetermined cranking time T2 is counted by the timer, and thus continues the cranking process (the loop of No in S10 of Fig. 3). When the predetermined cranking time T2 is counted (Yes in S10 of Fig. 3), the energization of the starter motor 12 is stopped to end the cranking process (S11 in Fig. 3 / t4 in Fig. 4), and the discharge process of the residual gas fuel is completed (END in Fig. 3).

[0111] 〔Modification Example of Residual Gas Fuel Discharge Device〕(Example 2) As described above with reference to FIGS. 1 to 4, in the residual gas fuel discharge device 2 of the gaseous fuel engine unit, the atmospheric opening of the fuel supply passage 22 (22a, 22b) and the introduction of nitrogen gas by the fuel discharge control means 75 in the supply passage are configured to be performed until a predetermined discharge time T1 is counted by a timer, and the cranking process of the engine 10 by the cranking control means 77 is configured to be performed until a predetermined cranking time T2 is counted by a timer.

[0112] On the other hand, in the configuration (Example 2) shown in FIGS. 5 to 8, a hydrogen concentration detector 55 for detecting the hydrogen concentration in the bleed passage 54 communicating with the fuel supply passage 22 (primary side fuel supply passage 22a, secondary side fuel supply passage 22b) and a hydrogen concentration detector 15 for detecting the hydrogen concentration in the exhaust system 13 of the engine 10 are respectively provided (see FIG. 5). When the hydrogen concentration in the bleed passage 54, and thus the hydrogen concentration in the fuel supply passage 22 (22a, 22b), becomes less than a predetermined threshold value C1 (for example, less than 4% hydrogen concentration) (Yes in S7' of FIG. 7 / t3 in FIG. 8), the fuel discharge process in the supply passage by the fuel discharge control means 75 in the supply passage (atmospheric opening of the fuel supply passage 22 (22a, 22b) and introduction of nitrogen gas to the fuel supply passage 22 (22a, 22b)) is terminated. At the same time, when the hydrogen concentration in the exhaust system 13 of the engine 10 becomes less than a predetermined threshold value (for example, less than 4% hydrogen concentration) (Yes in S10' of FIG. 7 / t4 in FIG. 8), the cranking process (energization of the starter motor 12) by the cranking control means 77 is stopped. Other configurations are the same as those of Example 1 described with reference to FIGS. 1 to 4.

[0113] In the illustrated example, the end of the fuel discharge process in the supply passage by the fuel discharge control means 75 in the supply passage is configured to be based on the hydrogen concentration in the bleed passage 54 (54a, 54b). However, instead of this configuration, the hydrogen concentration in the fuel supply passage 22 may be directly detected, and the fuel discharge process in the supply passage may be terminated when it is detected that the hydrogen concentration in the fuel supply passage 22 has become less than a predetermined threshold value C1.

[0114] In the configuration of the first embodiment described with reference to FIGS. 1 to 4, since the fuel discharge process in the supply passage and the cranking process are terminated at a predetermined discharge time T1 and a predetermined cranking time T2, even if hydrogen gas still remains in the fuel supply passage 22 (22a, 22b), the bleed passage 54, the combustion chamber of the engine 10, or the exhaust system 13 of the engine 10 after the predetermined discharge time T1 or the cranking time T2 has elapsed, the process is terminated. Also, even if the discharge of hydrogen gas in the fuel supply passage 22, the bleed passage 54, the engine 10, or the exhaust system 13 of the engine 10 is completed, the fuel discharge process in the supply passage and the cranking process are continued unnecessarily until the predetermined discharge time T1 and the predetermined cranking time T2 have elapsed.

[0115] On the other hand, in the configuration of the embodiment (second embodiment) shown in FIGS. 5 to 8, hydrogen concentration detectors 55 and 15 for detecting the hydrogen concentration in the bleed passage 54 and the exhaust system 13 of the engine 10 are provided, respectively, and the hydrogen concentration in the bleed passage 54 and the exhaust system 13 of the engine 10 is constantly monitored to terminate the residual gas fuel discharge process and the cranking process. As a result, the fuel discharge process in the supply passage and the cranking process do not end while gaseous fuel with a concentration exceeding the threshold values C1 and C2 remains, and the fuel discharge process in the supply passage and the cranking process are not continued unnecessarily after the gaseous fuel concentration becomes less than the threshold values C1 and C2, and the residual gas fuel can be discharged reliably and efficiently.

[0116] In the above description, the configuration for measuring the hydrogen concentration in the bleed passage 54 and the exhaust system 13 of the engine 10 to terminate the fuel discharge process in the supply passage and the cranking process has been described. However, the nitrogen concentration in the bleed passage 54 and the exhaust system 13 of the engine 10 may be measured, and for example, the fuel discharge process in the supply passage and the cranking process may be terminated when the nitrogen concentration exceeds 96%.

[0117] In the examples shown in FIGS. 5 to 8, the configuration in which both the fuel discharge process in the supply passage and the cranking process are terminated when the hydrogen concentration becomes less than a predetermined threshold value has been described. However, for either the fuel discharge process in the supply passage or the cranking process, it may be configured to end when a predetermined exhaust time T1 or a predetermined cranking time T2 has elapsed, and to end only when the hydrogen concentration becomes less than a predetermined threshold value for the other process.

Explanation of Signs

[0118] 1 Gas fuel engine unit (hydrogen engine unit) 2 Residual gas fuel discharge device 10 Engine 11 Engine control unit (ECU) 12 Starter motor 13 Exhaust system (of engine) 15 Hydrogen concentration detector 20 Gas fuel source (hydrogen source) 22 Fuel supply passage (hydrogen gas supply passage) 22a Primary side fuel supply passage 22b Secondary side fuel supply passage 24 Pressure regulator (for gas fuel) 30 Inert gas source (nitrogen source) 30a Nitrogen gas cylinder 30b Pressure regulator (for inert gas) 32 Inert gas introduction passage (nitrogen gas introduction passage) 40 Gas fuel supply control mechanism 41 Gas fuel supply valve 42 Gas fuel supply valve control circuit 43 Gas fuel supply control electromagnetic valve 50 Bleeding mechanism 50a Primary side bleeding mechanism 50b Secondary side bleeding mechanism 51 Bleeding valve 51a Primary side bleeding valve 51b Secondary side bleeding valve 52 Bleeding valve control circuit 52a Primary side bleeding valve control circuit 52b Secondary-side Bleed Valve Control Circuit 53 Solenoid Valve for Bleed Valve Control 53a Solenoid Valve for Primary-side Bleed Valve Control 53b Solenoid Valve for Secondary-side Bleed Valve Control 54(54a, 54b) Bleed Flow Path 55 Hydrogen Concentration Detector 60 Inert Gas Introduction Control Mechanism 61 Electromagnetic On / Off Valve 70 Control Device (Electronic Control Device) 71 Stop Condition Judgment Means 72 Engine Stop Control Means 73 Engine Stop Judgment Means 74 Gas Fuel Supply Stop Control Means 75 Fuel Discharge Control Means in Supply Path 77 Cranking Control Means 110 Engine 117 Supercharger 120 Hydrogen Source 122 Hydrogen Fuel Supply Pipe 141 Flow Rate Adjusting Valve 181 Liquid Fuel Supply Section 185 Hydrogen Fuel Supply Section 187 Bleed Valve T1 Discharge Time T2 Cranking Time C1 Threshold Value (of Hydrogen Concentration in Fuel Supply Path / Bleed Flow Path) C2 Threshold Value (of Hydrogen Concentration in Exhaust System of Engine) TH Threshold Value (of Pressure in Gas 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, 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, and 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 this.

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 a gas fuel engine unit according to claim 1 is characterized by this.

3. 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. The method for discharging residual gas fuel in a gas fuel engine unit according to claim 1 is characterized by this.

4. 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. The method for discharging residual gas fuel in a gas fuel engine unit according to claim 2 is characterized by this.

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

6. The method for discharging residual gaseous fuel in a gaseous fuel engine unit according to claim 2, characterized in that the cranking process is terminated when a predetermined cranking time has elapsed or when the concentration of gaseous fuel in the exhaust system of the engine drops below a predetermined threshold value, which is used as the cranking end condition.

7. The method for discharging residual gaseous fuel in a gaseous fuel engine unit according to claim 4, characterized in that the cranking process is terminated when a predetermined cranking time has elapsed or when the concentration of gaseous fuel in the exhaust system of the engine drops below a predetermined threshold value, which is used as the cranking end condition.

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 performed by introducing an inert gas into the primary side fuel supply passage and the secondary side fuel supply passage respectively while the primary side fuel supply passage and the secondary side fuel supply passage are each open to the atmosphere. The method for discharging residual gaseous fuel in a gaseous fuel engine unit according to any one of claims 1 to 4, 6, and 7, characterized in that the fuel discharge process in the supply passage is terminated by ending the atmospheric opening of both the primary side fuel supply passage and the secondary side fuel supply passage and stopping the introduction of inert gas into both the primary side fuel supply passage and the secondary side fuel supply passage.

9. In a gaseous fuel engine unit including an engine capable of using gaseous fuel as fuel and a fuel supply passage for supplying gaseous fuel from a gaseous fuel source to the engine. An inert gas introduction passage communicating between the inert gas source and the fuel supply passage is provided. A gaseous fuel supply control mechanism for opening and closing between the gaseous fuel source and the fuel supply passage. A gas discharge mechanism for starting and stopping the atmospheric opening 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. A control device is provided, which comprises an electronic control unit for controlling the operations of the gaseous fuel supply control mechanism, the air bleeding mechanism, and the inert gas introduction control mechanism. By the control device, after the engine stops, a gaseous fuel supply stop control means is provided to execute a gaseous fuel supply stop process of operating the gaseous fuel supply control mechanism to cut off the communication between the gaseous fuel source and the gaseous supply passage and stop the supply of gaseous fuel to the fuel supply passage. After the execution of the gaseous fuel supply stop process by the gaseous fuel supply stop control means, a fuel discharge control means in the supply passage is realized to execute a fuel discharge process in the supply passage for discharging the gaseous fuel remaining in the fuel supply passage to the atmosphere. The fuel discharge control means in the supply passage operates the air bleeding 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, thereby executing the fuel discharge process in the supply passage. At the same time, when a predetermined discharge end condition is satisfied, the air bleeding mechanism is operated to end the opening of the fuel supply passage to the atmosphere, and the inert gas introduction control mechanism is operated to stop the introduction of inert gas into the fuel supply passage, thereby ending the fuel discharge process in the supply passage. A device for discharging residual gaseous fuel in a gaseous fuel engine unit is characterized in that it is configured as such.

10. The gaseous fuel supply control mechanism is composed of a gaseous fuel supply valve which is a pneumatic valve for opening and closing between the gaseous fuel source and the fuel supply passage, a gaseous fuel supply valve control circuit for introducing inert gas from the inert gas source as an operating pressure into the gaseous fuel supply valve, and a solenoid valve for gaseous fuel supply control for performing communication and interruption between the inert gas source and the gaseous fuel supply valve control circuit. The air bleeding mechanism is composed of a bleed valve which is a pneumatic valve for opening the fuel supply passage to the atmosphere, a bleed valve control circuit for introducing inert gas from the inert gas source as an operating pressure into the bleed valve, and a solenoid valve for bleed valve control for performing communication and interruption between the inert gas source and the bleed valve control circuit. At the same time, the inert gas introduction control mechanism is composed of an electromagnetic on-off valve provided in the inert gas introduction passage. The solenoid valve for gaseous fuel supply control is configured to be operable by the gaseous fuel supply stop control means of the control device. The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to claim 9, wherein the electromagnetic valve for bleed valve control 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.

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 via the electromagnetic on-off valve, The gas fuel supply valve control circuit via the gas fuel supply control electromagnetic valve, The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to claim 10, wherein the exhaust valve control circuit is respectively communicated via the bleed valve control electromagnetic valve.

12. The control device realizes cranking control means for rotating the starter motor of the engine after the fuel discharge process in the supply passage by the fuel discharge control means in the supply passage until a predetermined cranking end condition is satisfied. The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to any one of claims 9 to 11.

13. The fuel discharge control means in the supply passage ends the fuel discharge process in the supply passage with the passage of a predetermined discharge time or a decrease in the gaseous fuel concentration in the fuel supply passage below a predetermined threshold as the discharge end condition. The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to any one of claims 9 to 11.

14. A bleed flow path for discharging the gaseous fuel remaining in the fuel supply passage to the atmosphere is provided in communication with the fuel supply passage, The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to claim 13, wherein the fuel discharge control means in the supply passage determines that the gaseous fuel concentration in the fuel supply passage has decreased below the predetermined threshold when the gaseous fuel concentration in the bleed flow path has decreased below the predetermined threshold.

15. The exhaust device for residual gaseous fuel in the gaseous fuel engine unit according to claim 12, wherein the cranking control means ends the cranking process with the passage of a predetermined cranking time or a decrease in the gaseous fuel concentration in the exhaust system of the engine below a predetermined threshold 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 that vents the primary-side fuel supply passage to the atmosphere as the bleed valve, and a secondary-side bleed valve that vents the secondary-side fuel supply passage to the atmosphere. As the bleed valve control circuit, a primary-side bleed valve control circuit that introduces an operating pressure to the primary-side bleed valve and a secondary-side bleed valve control circuit that introduces an operating pressure to the secondary-side bleed valve are respectively provided. As the electromagnetic valve for bleed valve control, a primary-side electromagnetic valve for bleed valve control that connects and disconnects the communication between the inert gas source and the primary-side bleed valve control circuit, and a secondary-side electromagnetic valve for bleed valve control that connects and disconnects the communication between the inert gas source and the secondary-side bleed valve control circuit are respectively provided. The device for discharging residual gaseous fuel in the gaseous fuel engine unit according to claim 10 or 11, characterized in that.

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