Power generation system and series hybrid moving body

Abstract

This power generation system is provided with a power generator, an internal combustion engine that includes a combustion chamber and an intake port for guiding air to the combustion chamber and that drives the power generator, a fuel injector for supplying hydrogen gas to the intake port of the internal combustion engine, and a fuel supply path for fluidly connects at least one hydrogen fuel tank storing a hydrogen storage alloy to the fuel injector.

Description

Power generation system and series hybrid vehicle

[0001] The present disclosure relates to a power generation system and a series hybrid vehicle.

[0002] Patent Document 1 discloses a vehicle including a hydrogen generation system and an engine to which hydrogen gas generated by the hydrogen generation system is supplied as fuel. In the hydrogen generation system, hydrogen gas is generated by a dehydrogenation reaction in a reactor to which methylcyclohexane (MCH) is supplied from an MCH tank. The generated hydrogen gas is directly supplied to the combustion chamber of the engine by a direct injection valve, and when the amount of hydrogen supplied by the direct injection valve is insufficient, it is further supplied to the intake port of the engine by a port injection valve.

[0003] Japanese Patent Application Laid-Open No. 2009-114878

[0004] However, in the vehicle disclosed in Patent Document 1, it is necessary to mount a hydrogen generation system on the vehicle, which increases the vehicle weight and occupied space. Also, when the user increases or decreases the accelerator opening, if each valve and pump is not quickly controlled to increase or decrease the output of the engine, the output of the engine will not meet the requirements and become unstable.

[0005] One aspect of the present disclosure aims to stably operate an internal combustion engine while compactifying a hydrogen supply source used as fuel for the internal combustion engine.

[0006] A power generation system according to one aspect of the present disclosure includes a generator, an internal combustion engine including a combustion chamber and an intake port that guides air to the combustion chamber and drives the generator, a fuel injector that supplies hydrogen gas to the intake port of the internal combustion engine, and a fuel supply path that fluidly connects at least one hydrogen fuel tank incorporating a hydrogen storage alloy to the fuel injector.

[0007] A series hybrid mobile body according to one aspect of the present disclosure comprises a power generation system, a battery charged by the generator of the power generation system, an electric motor powered by the battery, a mobile body control circuit configured to control the electric motor, and a propulsion unit driven by the electric motor to generate a thrust force for moving the mobile body.

[0008] According to one aspect of this disclosure, it is possible to make the hydrogen supply source used as fuel for the internal combustion engine more compact while enabling stable operation of the internal combustion engine.

[0009] Figure 1 is a schematic diagram of a series hybrid mobile body equipped with a power generation system according to an embodiment. Figure 2 is a graph showing the hydrogen release pressure of the hydrogen storage alloy in Figure 1. Figure 3 is a flowchart relating to the operating modes of the mobile body in Figure 1. Figure 4 is a flowchart relating to the emergency stop of the mobile body in Figure 1.

[0010] Embodiments will be described below with reference to the drawings.

[0011] Figure 1 is a schematic diagram of a series hybrid mobile body 1 equipped with a power generation system 10 according to an embodiment. The power generation system 10 is mounted on the series hybrid mobile body 1 as a power source. The mobile body 1 may be a manned vehicle or an unmanned vehicle. The mobile body 1 is, for example, a vehicle equipped with wheels 13 that serve as drive wheels, such as a two-wheeled, three-wheeled, or four-wheeled vehicle, but it may also be a robot. The wheels 13 are an example of a propulsion system that generates thrust to move the mobile body 1. The mobile body 1 may also be a ship, an aircraft, etc. In that case, a propeller or the like can be used as a propulsion system. The power generation system 10 may be mounted on a robot as a power source for the robot.

[0012] The power generation system 10 includes a generator 21 and an internal combustion engine 22 that drives the generator 21. The internal combustion engine 22 includes a cylinder 31, a piston 32, a crankshaft 33, a connecting rod 34, an intake valve 35, an exhaust valve 36, a spark plug 37, etc. The cylinder 31 has a combustion chamber 31a, an intake port 31b that guides intake air into the combustion chamber 31a, and an exhaust port 31c that guides exhaust air from the combustion chamber 31a to the outside. The combustion chamber 31a is defined by a piston 32 that is slidably housed in the cylinder 31. The cylinder 31 is fitted with a spark plug 37 that ignites the hydrogen gas in the combustion chamber 31a.

[0013] An intake passage 41 is fluidly connected to the intake port 31b of the internal combustion engine 22. The intake passage 41 guides air purified by the air cleaner to the intake port 31b. A throttle valve 42 is located in the intake passage 41. The amount of intake air supplied to the internal combustion engine 22 is regulated by the throttle valve 42. The throttle valve 42 is driven by a valve motor 43. The intake port 31b is opened and closed by an intake valve 35. The exhaust port 31c is opened and closed by an exhaust valve 36.

[0014] A fuel injector 44 is positioned in the intake passage 41. The fuel injector 44 injects hydrogen gas as fuel into the region between the throttle valve 42 and the intake port 31b in the intake passage 41. That is, the fuel injector 44 supplies hydrogen gas to the intake port 31b. The fuel injector 44 may also be attached to a throttle body having a throttle valve 42 to inject combustion gas into the intake passage 41. That is, the fuel injector 44 does not need to inject hydrogen gas directly into the combustion chamber 31a, but rather injects hydrogen gas upstream of the combustion chamber 31a.

[0015] The piston 32 is mechanically connected to the crankshaft 33 via a connecting rod 34. The driven shaft 21a of the generator 21 is connected to the crankshaft 33 so as to rotate at a constant ratio to the rotational speed of the crankshaft 33. Specifically, the driven shaft 21a of the generator 21 is coupled to the crankshaft 33 of the internal combustion engine 22 on the same axis. The driven shaft 21a of the generator 21 may also be connected to the crankshaft 33 via a power relay mechanism such as a gear pair having a constant reduction ratio. The internal combustion engine 22 is provided with a rotational speed sensor 45 for detecting the rotational speed of the crankshaft 33.

[0016] The generator 21 generates electricity when its driven shaft 21a is driven by the internal combustion engine 22. In this embodiment, in addition to its power generation function, the generator 21 also functions as a starter motor to start the internal combustion engine 22. The generator 21 is connected to the inverter 12. The inverter 12 is electrically connected to the battery 11. The battery 11 can store the electricity generated by the generator 21 using the mechanical energy generated by the internal combustion engine 22. The generator 21 is provided with a temperature sensor 48 for detecting the temperature of the generator 21. The battery 11 is provided with a battery state sensor 60 for detecting the battery state, including the remaining charge or temperature of the battery 11.

[0017] The mobile unit 1 is equipped with an electric motor 14 that drives the wheels 13. That is, the electric motor 14 is used as a traction motor. The electric motor 14 is electrically connected to the battery 11 via an inverter 15. The electric motor 14 drives the wheels 13 with power supplied from the battery 11 via the inverter 15, thereby causing the mobile unit 1 to move.

[0018] The power generation system 10 includes a plurality of replaceable hydrogen fuel tanks 23. There may be only one hydrogen fuel tank 23 instead of a plurality. In this embodiment, the power generation system 10 includes a first hydrogen fuel tank 23A and a second hydrogen fuel tank 23B as the plurality of hydrogen fuel tanks 23. The hydrogen fuel tanks 23A and 23B each contain a hydrogen storage alloy H that has absorbed hydrogen as fuel for the internal combustion engine 22. The hydrogen fuel tanks 23A and 23B are fluidly connected to the fuel injector 44 via a fuel supply passage 24. The hydrogen fuel tanks 23A and 23B are connected to the fuel supply passage 24 in a parallel configuration.

[0019] The power generation system 10 includes a valve system 26 capable of individually shutting off the fluid connection between the first hydrogen fuel tank 23A and the fuel supply line 24, and the fluid connection between the second hydrogen fuel tank 23B and the fuel supply line 24. The valve system 26 includes a first shut-off valve 26A that can open and close the discharge port of the first hydrogen fuel tank 23A relative to the fuel supply line 24, and a second shut-off valve 26B that can open and close the discharge port of the second hydrogen fuel tank 23B relative to the fuel supply line 24. The shut-off valves 26A and 26B may be solenoid valves. The valve system 26 may also include a three-way valve interposed between the discharge port of the first hydrogen fuel tank 23A, the discharge port of the second hydrogen fuel tank 23B, and the fuel supply line 24.

[0020] A pressure regulating valve 25 is located in the fuel supply line 24. The pressure regulating valve 25 adjusts the pressure of the hydrogen gas supplied from the hydrogen fuel tank 23 and flowing through the fuel supply line 24 so that the pressure of the hydrogen gas reaches a predetermined specified pressure P1. The pressure regulating valve 25 may be a valve that adjusts the pressure mechanically, but it may also be a valve that adjusts the pressure by electrical control.

[0021] The fuel injector 44 is a fuel injection valve, and hydrogen gas at a specified pressure P1 is supplied to the fuel injector 44 from the pressure regulating valve 25. Therefore, the flow rate of hydrogen gas supplied from the fuel injector 44 to the intake port 31b is determined by the opening time of the fuel injector 44. The specified pressure P1 set in the pressure regulating valve 25 is less than the pressure required to directly inject hydrogen gas into the combustion chamber 31a. The specified pressure P1 is greater than standard atmospheric pressure. The specified pressure P1 can be, for example, a value between 0.2 MPa and 0.4 MPa.

[0022] The fuel supply line 24 is equipped with a pressure sensor 27 that detects the pressure of the hydrogen gas flowing downstream of the pressure regulating valve 25. The fuel supply line 24 is also equipped with a flow sensor 28 that detects the flow rate of the hydrogen gas flowing upstream of the pressure regulating valve 25.

[0023] The fuel supply line 24 does not have a pressurizing pump. That is, the hydrogen gas released by the hydrogen storage alloy H reaches the pressure regulating valve 25 without being pressurized. Because the hydrogen pressure released by the hydrogen storage alloy H is utilized without using a pressurizing pump, the power generation system 10 can be made more compact and the energy consumption of the power generation system 10 can be reduced.

[0024] The internal combustion engine 22 is not equipped with a fuel injector that directly injects hydrogen gas into the combustion chamber 31a. The only hydrogen gas supplied to the combustion chamber 31a of the internal combustion engine 22 is the hydrogen gas that passes through the intake port 31b and is supplied to the combustion chamber 31a. As the piston 32 moves toward the side that increases the volume of the combustion chamber 31a, a negative pressure is created in the combustion chamber 31a, and hydrogen gas flows into the combustion chamber 31a from the intake port 31b opened by the intake valve 35. Therefore, even if the injection pressure of hydrogen gas by the fuel injector 44 is low, hydrogen gas can be supplied from the fuel injector 44 to the intake port 31b. As a result, it is not necessary to pressurize the hydrogen gas from the hydrogen fuel tank 23, and the internal combustion engine 22 can be operated stably even when using hydrogen storage alloy H, which has a relatively low hydrogen release pressure.

[0025] The power generation system 10 includes an engine controller 51, a fuel supply controller 52, a mobile unit controller 53, and a generator controller 54. Two, three, or all of the engine controller 51, fuel supply controller 52, mobile unit controller 53, and generator controller 54 may be integrated into a single controller. In this embodiment, the engine controller 51, fuel supply controller 52, mobile unit controller 53, and generator controller 54 as a whole may be referred to as controller 50.

[0026] The engine controller 51 includes an engine control circuit 51a. Specifically, the engine controller 51 includes a processor, system memory, storage memory, and an interface. The processor may include a CPU. The system memory may include volatile memory. The storage memory may include non-volatile memory. The storage memory may be a hard disk, flash memory, or a combination thereof. The storage memory stores the control program. An example of the engine control circuit 51a is a configuration in which the processor executes the control program read from the storage memory to the system memory.

[0027] The engine control circuit 51a receives detection signals from the rotational speed sensor 45 and the pressure sensor 27. The engine control circuit 51a controls the spark plug 37, valve motor 43, and fuel injector 44. For example, based on the rotational speed detected by the rotational speed sensor 45, the engine control circuit 51a controls the spark plug 37, valve motor 43, and fuel injector 44 so that the rotational speed of the crankshaft 33 remains constant. This allows the internal combustion engine 22 to be operated in an efficient rotational speed range, thereby increasing the energy efficiency of the power generation system 10. Furthermore, the rotational speed of the generator 21 can be kept constant without the need to install any special equipment between the internal combustion engine 22 and the generator 21, enabling stable power generation.

[0028] The fuel supply controller 52 includes a fuel supply control circuit 52a. Specifically, the fuel supply controller 52, like the engine controller 51, includes a processor, system memory, storage memory, and an interface. The storage memory stores the control program. One example of a configuration in which the processor executes the control program read from the storage memory to the system memory is the fuel supply control circuit 52a.

[0029] The fuel supply control circuit 52a receives detection signals from the pressure sensor 27, the flow sensor 28, the pressure sensor 46, and the temperature sensor 47. The fuel supply control circuit 52a can control the valve system 26 and communicate with the engine control circuit 51a. For example, the fuel supply control circuit 52a sends a command to the engine control circuit 51a based on the pressure detected by the pressure sensor 27. For example, if the pressure detected by the pressure sensor 27 is lower than a specified pressure P1, the fuel supply control circuit 52a sends an output limit command to the engine control circuit 51a. The fuel supply control circuit 52a may also control the valve system 26 based on the flow rate detected by the flow sensor 28. The fuel supply control circuit 52a may calculate the remaining amount of hydrogen absorbed by the hydrogen storage alloy H based on the pressure detected by the pressure sensor 46 and the temperature detected by the temperature sensor 47.

[0030] The mobile controller 53 includes a mobile control circuit 53a. Specifically, the mobile controller 53, like the engine controller 51 and fuel supply controller 52, includes a processor, system memory, storage memory, and an interface. The storage memory stores the control program. One example of a configuration in which the processor executes the control program read from the storage memory to the system memory is the mobile control circuit 53a.

[0031] The mobile control circuit 53a receives the detection signal from the accelerator sensor 49. The accelerator sensor 49 detects the amount of acceleration request corresponding to the amount of operation of the accelerator control device, such as the accelerator pedal and accelerator grip, operated by the driver of the mobile vehicle 1. If the mobile vehicle 1 is an unmanned vehicle, the mobile control circuit 53a calculates the amount of acceleration request according to its own control program. The mobile control circuit 53a can control the inverter 15 to control the electric motor 14 and can communicate with the engine control circuit 51a. When the amount of acceleration request detected by the accelerator sensor 49 increases, the mobile control circuit 53a controls the inverter 15 to increase the driving force of the electric motor 14.

[0032] The generator controller 54 includes a generator control circuit 54a. Specifically, the generator controller 54 includes a processor, system memory, storage memory, and an interface. The processor may include a CPU. The system memory may include volatile memory. The storage memory may include non-volatile memory. The storage memory may be a hard disk, flash memory, or a combination thereof. The storage memory stores the control program. One example of a configuration in which the processor executes the control program read from the storage memory to the system memory is the generator control circuit 54a.

[0033] The generator control circuit 54a receives detection signals from the battery state sensor 60 or the temperature sensor 48. The generator control circuit 54a can control the inverter 12 to control the generator 21 and can communicate with the engine control circuit 51a. The generator control circuit 54a adjusts the amount of power generated by the generator 21 by controlling the inverter 12 based on the detection signals from the battery state sensor or the temperature sensor 48. For example, if the remaining charge detected by the battery state sensor 60 exceeds a predetermined threshold, the generator control circuit 54a may control the inverter 12 to reduce the amount of power generated by the generator 21 compared to when it is below the threshold. If the temperature of the generator 21 detected by the temperature sensor 48 exceeds a predetermined threshold, the generator control circuit 54a may control the inverter 12 to reduce the amount of power generated by the generator 21 compared to when it is below the threshold.

[0034] Figure 2 is a graph showing the hydrogen release pressure of the hydrogen storage alloy H shown in Figure 1. As shown in Figure 2, the amount of hydrogen stored per unit weight of the hydrogen storage alloy H, the temperature of the hydrogen storage alloy H, and the pressure of the hydrogen released from the hydrogen storage alloy H have a predetermined correlation with each other. This correlation can be customized by the design of the hydrogen storage alloy H.

[0035] The pressure of hydrogen released from hydrogen storage alloy H increases with increasing hydrogen storage capacity per unit weight of hydrogen storage alloy H. The pressure of hydrogen released from hydrogen storage alloy H also increases with increasing temperature of hydrogen storage alloy H. For example, if the specified pressure P1, which is the target pressure at which the pressure regulating valve 25 reduces pressure, is set to 0.3 MPa, the hydrogen release pressure from hydrogen storage alloy H can exceed the specified pressure P1 for most of the hydrogen storage capacity range of hydrogen storage alloy H.

[0036] In the power generation system 10, a hydrogen fuel tank 23 incorporating such a hydrogen storage alloy H is used, which allows for a more compact hydrogen supply source for use as fuel for the internal combustion engine 22. Furthermore, since the internal combustion engine 22 that drives the generator 21 has smaller output fluctuations compared to the internal combustion engine that drives the drive wheels of a mobile body, it prevents the hydrogen gas supply pressure required by the internal combustion engine 22 from becoming excessively high.

[0037] Furthermore, the hydrogen gas supply pressure required to supply hydrogen gas to the intake port 31b of the internal combustion engine 22 is significantly lower than the hydrogen gas supply pressure required to directly inject hydrogen gas into the combustion chamber 31a of the internal combustion engine 22. Therefore, by using hydrogen storage alloy H, the internal combustion engine 22 can stably burn hydrogen gas even when the pressure of the hydrogen gas released from the hydrogen fuel tank 23 is low.

[0038] Furthermore, as shown in the graph in Figure 2, the remaining amount of hydrogen absorbed by the hydrogen storage alloy H can be estimated from the hydrogen release pressure of the hydrogen storage alloy H and the temperature of the hydrogen storage alloy H. Therefore, the power generation system 10 includes a pressure sensor 46 for detecting the pressure of the hydrogen gas released from the hydrogen fuel tank 23 and a temperature sensor 47 for detecting the temperature of the hydrogen fuel tank 23. The pressure sensor 46 detects, for example, the pressure of the hydrogen gas flowing in the portion of the fuel supply line 24 between the hydrogen fuel tank 23 and the pressure regulating valve 25. The temperature sensor 47 indirectly detects the temperature of the hydrogen storage alloy H by, for example, detecting the temperature of the hydrogen fuel tank 23.

[0039] The fuel supply controller 52 has pre-stored a first correlation between the pressure detected by the pressure sensor 46, the temperature detected by the temperature sensor 47, and the remaining amount of hydrogen absorbed by the hydrogen storage alloy H. The fuel supply controller 52 refers to the first correlation and estimates the remaining amount of hydrogen absorbed by the hydrogen storage alloy H based on the pressure detected by the pressure sensor 46 and the temperature detected by the temperature sensor 47. The fuel supply controller 52 displays the estimated remaining amount on the display of the mobile unit 1.

[0040] The first correlation can be, for example, a calculation formula that takes the pressure detected by the pressure sensor 46 and the temperature detected by the temperature sensor 47 as inputs and outputs the remaining amount of hydrogen absorbed by the hydrogen storage alloy H. The first correlation may also be a table showing the relationship between the pressure detected by the pressure sensor 46, the temperature detected by the temperature sensor 47, and the remaining amount of hydrogen absorbed by the hydrogen storage alloy H.

[0041] The fuel supply controller 52 may pre-store a second correlation between the pressure detected by the pressure sensor 27 and the opening time of the fuel injector 44. The fuel supply controller 52 may refer to the second correlation and estimate the remaining amount of hydrogen stored in the hydrogen storage alloy H based on the pressure detected by the pressure sensor 27 and the opening time of the fuel injector 44. The second correlation can be, for example, a calculation formula that takes the pressure detected by the pressure sensor 27 and the opening time of the fuel injector 44 as inputs and outputs the remaining amount of hydrogen stored in the hydrogen storage alloy H. The second correlation can also be a table showing the relationship between the pressure detected by the pressure sensor 27, the opening time of the fuel injector 44, and the remaining amount of hydrogen stored in the hydrogen storage alloy H.

[0042] Figure 3 is a flowchart relating to the operating modes of the mobile unit 1 in Figure 1. As shown in Figure 3, in step S1, the engine control circuit 51a acquires state information of the power generation system 10. In step S2, the engine control circuit 51a determines whether the state information satisfies predetermined conditions. If it is determined that the state information does not satisfy the predetermined conditions, the engine control circuit 51a sets the operating mode of the internal combustion engine 22 to the first mode in step S3. On the other hand, if it is determined that the state information satisfies the predetermined conditions, the engine control circuit 51a sets the operating mode of the internal combustion engine 22 to the second mode in step S4.

[0043] The second mode is a mode in which the output of the internal combustion engine 22 is lower than that of the first mode under the same conditions. For example, the first mode may be called the normal mode and the second mode may be called the output suppression mode. That is, even if the acceleration request amount detected by the accelerator sensor 49 is the same, the output of the internal combustion engine 22 in the second mode is set to be lower than that of the internal combustion engine 22 in the first mode. For example, when the engine control circuit 51a refers to a control map in which the intake air amount and fuel supply amount are determined based on the acceleration request amount and engine speed, the output limiting mode may be realized by multiplying the control map by a correction coefficient of less than 1.

[0044] The above-described state information may be the hydrogen release pressure of the hydrogen fuel tank 23 detected by the pressure sensor 46. The state information may be the hydrogen temperature in the hydrogen fuel tank 23 detected by the temperature sensor 47. The state information may be the estimated hydrogen amount of the hydrogen fuel tank 23. The estimated hydrogen amount of the hydrogen fuel tank 23 can be calculated from the hydrogen release pressure of the hydrogen fuel tank 23 detected by the pressure sensor 46 and the hydrogen temperature in the hydrogen fuel tank 23 detected by the temperature sensor 47 by referring to the graph in FIG. 2.

[0045] When the engine control circuit 51a determines in step S2 that the hydrogen release pressure of the hydrogen fuel tank 23 is not less than a predetermined threshold value, it may be configured to set the operation mode to the first mode in step S3, while when it determines in step S2 that the hydrogen release pressure of the hydrogen fuel tank 23 is less than the threshold value, it may be configured to set the operation mode to the second mode in step S4. When the engine control circuit 51a determines in step S2 that the estimated hydrogen amount of the hydrogen fuel tank 23 is not less than a predetermined threshold value, it may be configured to set the operation mode to the first mode in step S3, while when it determines in step S2 that the estimated hydrogen amount of the hydrogen fuel tank 23 is less than the threshold value, it may be configured to set the operation mode to the second mode in step S4.

[0046] When the engine control circuit 51a determines in step S2 that the hydrogen temperature of the hydrogen fuel tank 23 is not less than a predetermined threshold value, it may be configured to set the operation mode to the first mode in step S3, while when it determines in step S2 that the hydrogen temperature of the hydrogen fuel tank 23 is less than the threshold value, it may be configured to set the operation mode to the second mode in step S4. With such a configuration, when the remaining hydrogen amount in the hydrogen fuel tank 23 decreases, power generation can be continued while reducing the efficiency of the internal combustion engine 22 and the power generation capacity of the generator 21, and the remaining hydrogen in the hydrogen fuel tank 23 can be effectively utilized.

[0047] Also, the state information may be the temperature of the generator 21 detected by the temperature sensor 48. The state information may be the battery state detected by the battery state sensor 60. When it is determined in step S2 that the temperature of the generator 21 is not equal to or higher than a predetermined threshold value, the engine control circuit 51a sets the operation mode to the first mode in step S3. On the other hand, when it is determined in step S2 that the temperature of the generator 21 is equal to or higher than the threshold value, the operation mode may be set to the second mode in step S4. When it is determined in step S2 that the remaining amount of the battery 11 is not less than a predetermined threshold value, the engine control circuit 51a sets the operation mode to the first mode in step S3. On the other hand, when it is determined in step S2 that the remaining amount of the battery 11 is less than the threshold value, the operation mode may be set to the second mode in step S4.

[0048] When it is determined in step S2 that the temperature of the battery 11 is not equal to or higher than a predetermined threshold value, the engine control circuit 51a sets the operation mode to the first mode in step S3. On the other hand, when it is determined in step S2 that the temperature of the battery 11 is equal to or higher than the threshold value, the operation mode may be set to the second mode in step S4. With such a configuration, power generation can be appropriately continued while taking into account the state of the generator 21 or the battery 11.

[0049] FIG. 4 is a flowchart regarding the emergency stop of the moving body 1 in FIG. 1. As shown in FIG. 4, in S11, the fuel supply control circuit 52a acquires the flow rate of hydrogen gas in the fuel supply passage 24 detected by the flow rate sensor 28. In step S12, the fuel supply control circuit 52a acquires the flow rate of hydrogen gas in the fuel injector 44. Specifically, the fuel supply control circuit 52a acquires the pressure detected by the pressure sensor 27 and the opening time of the fuel injector 44, and calculates the injection amount of hydrogen gas by the fuel injector 44 as the flow rate from the acquired pressure and opening time.

[0050] The fuel supply control circuit 52a determines whether the hydrogen gas flow rate obtained in step S11 and the hydrogen gas injection amount calculated in step S12 are mismatched. Specifically, the fuel supply control circuit 52a determines that a mismatch has occurred if the difference obtained by subtracting the hydrogen gas injection amount calculated in step S12 from the hydrogen gas flow rate obtained in step S11 exceeds a predetermined allowable value. For example, if a hydrogen gas leak occurs somewhere in the fuel supply passage 24, the difference will exceed the allowable value. If it is determined in step S13 that no mismatch has occurred, the process returns to step S11. On the other hand, if it is determined that a mismatch has occurred, the fuel supply control circuit 52a closes the shut-off valves 26A and 26B in step S14 and stops the internal combustion engine 22 in step S15.

[0051] As described above, the embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to the embodiments described above and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments to create new embodiments. For example, some components or methods in one embodiment may be applied to other embodiments, and some components in an embodiment can be separated from other components in that embodiment and extracted as appropriate. In addition, the components described in the attached drawings and detailed description include not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology.

[0052] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0053] [Embodiment] The embodiments described above are specific examples of the following embodiments.

[0054] (Aspect 1) A power generation system comprising: a generator; an internal combustion engine that drives the generator, including a combustion chamber and an intake port for introducing air into the combustion chamber; a fuel injector that supplies hydrogen gas to the intake port of the internal combustion engine; and a fuel supply passage that fluidly connects a hydrogen fuel tank containing a hydrogen storage alloy to the fuel injector.

[0055] According to Embodiment 1, since a hydrogen fuel tank incorporating a hydrogen storage alloy is used, the hydrogen supply source used as fuel for the internal combustion engine can be made more compact. Furthermore, since the output fluctuation of the internal combustion engine that drives the generator is smaller than that of the internal combustion engine that drives the drive wheels of a mobile body, the hydrogen gas supply pressure required by the internal combustion engine does not become high. Moreover, the hydrogen gas supply pressure required when supplying hydrogen gas to the intake port of the internal combustion engine is significantly lower than the hydrogen gas supply pressure required when directly injecting hydrogen gas into the combustion chamber of the internal combustion engine. Therefore, by using a hydrogen storage alloy, the internal combustion engine can stably burn hydrogen gas even when the pressure of the hydrogen gas released from the hydrogen fuel tank is low. Thus, the hydrogen supply source used as fuel for the internal combustion engine can be made more compact while the internal combustion engine can be operated stably.

[0056] (Aspect 2) The power generation system according to aspect 1, further comprising: an intake passage for guiding air to the intake port; a throttle valve disposed in the intake passage; a valve motor for driving the throttle valve; and an engine control circuit for controlling the valve motor and the fuel injector, wherein the engine control circuit controls the valve motor and the fuel injector so that the rotational speed of the internal combustion engine remains constant.

[0057] According to embodiment 2, the internal combustion engine can be operated in an efficient rotational speed range, thereby increasing the energy efficiency of the power generation system. Furthermore, the rotational speed of the generator can be kept constant without installing any special equipment between the internal combustion engine and the generator, enabling stable power generation.

[0058] (Aspect 3) The power generation system according to aspect 1 or 2, wherein the driven shaft of the generator is connected to the crankshaft of the internal combustion engine so as to rotate at a constant ratio to the rotational speed of the crankshaft of the internal combustion engine.

[0059] According to embodiment 3, by operating the internal combustion engine at a constant rotational speed, the generator can generate electricity stably, and hydrogen gas can be appropriately supplied to the internal combustion engine even when using a hydrogen storage alloy with a low hydrogen release pressure.

[0060] (Aspect 4) The power generation system according to any one of aspects 1 to 3, further comprising a pressure regulating valve for reducing the pressure of hydrogen gas flowing through the fuel supply line.

[0061] According to embodiment 4, since a pressurizing pump is not used by utilizing the hydrogen release pressure of the hydrogen storage alloy, the power generation system can be made more compact and the energy consumption of the power generation system can be reduced.

[0062] (Aspect 5) The power generation system according to any one of aspects 1 to 4, wherein the internal combustion engine is not provided with a fuel injector for directly injecting hydrogen gas into the combustion chamber.

[0063] According to embodiment 5, since it is no longer necessary to pressurize the hydrogen gas from the hydrogen fuel tank, the power generation system can be made more compact and the energy consumption of the power generation system can be reduced.

[0064] (Aspect 6) The power generation system according to any one of aspects 1 to 5, further comprising: an intake passage for guiding air to the intake port; a throttle valve disposed in the intake passage; a valve motor for driving the throttle valve; and an engine control circuit for controlling the valve motor and the fuel injector, wherein the engine control circuit acquires the pressure of the fuel supply passage, and when it determines that the acquired pressure is less than a predetermined specified pressure, changes the operating mode of the internal combustion engine to an output limiting mode.

[0065] According to embodiment 6, even if the amount of hydrogen absorbed in the hydrogen storage alloy decreases and the release hydrogen pressure drops, power generation can be continued, and the amount of unused hydrogen remaining in the hydrogen storage alloy can be reduced.

[0066] (Aspect 7) The power generation system according to any one of aspects 1 to 6, wherein the at least one hydrogen fuel tank includes a plurality of hydrogen fuel tanks, including a first hydrogen fuel tank and a second hydrogen fuel tank, and the power generation system further comprises a valve system capable of individually shutting off the fluid connection between the first hydrogen fuel tank and the fuel supply line, and the fluid connection between the second hydrogen fuel tank and the fuel supply line, and a fuel supply control circuit that controls the valve system to switch between the first hydrogen fuel tank and the second hydrogen fuel tank which supply hydrogen gas to the fuel supply line in accordance with the pressure of the hydrogen gas supplied from the hydrogen fuel tank to the fuel supply line.

[0067] According to embodiment 7, hydrogen gas can be stably supplied to the internal combustion engine from the fuel supply line by using multiple hydrogen fuel tanks.

[0068] (Aspect 8) The power generation system according to any one of aspects 1 to 7, further comprising a controller including an engine processing circuit for determining the operating mode of the internal combustion engine based on the required power, a fuel supply processing circuit, and a power generation processing circuit for controlling the generator, wherein the controller determines the operating mode based on at least one of the following: the hydrogen discharge pressure of the hydrogen fuel tank, the estimated amount of hydrogen in the hydrogen fuel tank, the hydrogen temperature of the hydrogen fuel tank, the temperature of the generator, and the state of the battery charged by the generator.

[0069] According to embodiment 8, the operating mode of the internal combustion engine changes based on at least one of the conditions regarding hydrogen in the hydrogen fuel tank, the temperature of the generator, and the state of the battery, so the internal combustion engine can be operated appropriately by considering the entire system.

[0070] (Aspect 9) A series hybrid mobile body comprising: a power generation system according to any one of aspects 1 to 8; a battery charged by the generator of the power generation system; an electric motor powered by electricity from the battery; a mobile body control circuit configured to control the electric motor; and a propulsion unit driven by the electric motor to generate a thrust force for moving the series hybrid mobile body.

[0071] According to embodiment 9, the fuel system can be made compact while still providing the required propulsion force for the mobile body.

[0072] 1 Mobile unit 10 Power generation system 11 Battery 13 Wheels, propulsion system 14 Electric motor 21 Generator 21a Driven shaft 22 Internal combustion engine 23 Hydrogen fuel tank 23A First hydrogen fuel tank 23B Second hydrogen fuel tank 24 Fuel supply passage 25 Pressure regulating valve 26 Shut-off valve 31a Combustion chamber 31b Intake port 33 Crankshaft 41 Intake passage 42 Throttle valve 43 Valve motor 44 Fuel injector 50 Controller 51a Engine control circuit 52a Fuel supply control circuit 53a Mobile unit control circuit 54a Generator control circuit H Hydrogen storage alloy

Claims

1. A power generation system comprising: a generator; an internal combustion engine that drives the generator, including a combustion chamber and an intake port for introducing air into the combustion chamber; a fuel injector that supplies hydrogen gas to the intake port of the internal combustion engine; and a fuel supply passage that fluidly connects at least one hydrogen fuel tank containing a hydrogen storage alloy to the fuel injector.

2. The power generation system according to claim 1, further comprising: an intake passage for guiding air to the intake port; a throttle valve disposed in the intake passage; a valve motor for driving the throttle valve; and an engine control circuit for controlling the valve motor and the fuel injector, wherein the engine control circuit controls the valve motor and the fuel injector so that the rotational speed of the internal combustion engine remains constant.

3. The power generation system according to claim 1, wherein the driven shaft of the generator is connected to the crankshaft of the internal combustion engine such that it rotates at a constant ratio to the rotational speed of the crankshaft of the internal combustion engine.

4. The power generation system according to claim 1, further comprising a pressure regulating valve for reducing the pressure of hydrogen gas flowing through the fuel supply line.

5. The power generation system according to claim 1, wherein the internal combustion engine is not provided with a fuel injector for directly injecting hydrogen gas into the combustion chamber.

6. The power generation system according to claim 1, further comprising: an intake passage for guiding air to the intake port; a throttle valve disposed in the intake passage; a valve motor for driving the throttle valve; and an engine control circuit for controlling the valve motor and the fuel injector, wherein the engine control circuit acquires the pressure of the fuel supply passage, and when it determines that the acquired pressure is less than a predetermined specified pressure, changes the operating mode of the internal combustion engine to an output limiting mode.

7. The power generation system according to claim 1, wherein the at least one hydrogen fuel tank includes a plurality of hydrogen fuel tanks, including a first hydrogen fuel tank and a second hydrogen fuel tank, and the power generation system further comprises: a valve system capable of individually shutting off the fluid connection between the first hydrogen fuel tank and the fuel supply line, and the fluid connection between the second hydrogen fuel tank and the fuel supply line; and a fuel supply control circuit that controls the valve system to switch between the first hydrogen fuel tank and the second hydrogen fuel tank which supply hydrogen gas to the fuel supply line in accordance with the pressure of the hydrogen gas supplied from the hydrogen fuel tank to the fuel supply line.

8. The power generation system according to claim 1, further comprising a controller including an engine processing circuit for determining the operating mode of the internal combustion engine based on the required power, a fuel supply processing circuit, and a power generation processing circuit for controlling the generator, wherein the controller determines the operating mode based on at least one of the following: the hydrogen discharge pressure of the hydrogen fuel tank, the estimated amount of hydrogen in the hydrogen fuel tank, the hydrogen temperature of the hydrogen fuel tank, the temperature of the generator, and the state of the battery charged by the generator.

9. A series hybrid mobile body comprising: a power generation system according to any one of claims 1 to 8; a battery charged by the generator of the power generation system; an electric motor powered by electricity from the battery; a mobile body control circuit configured to control the electric motor; and a propulsion unit driven by the electric motor to generate a thrust force for moving the series hybrid mobile body.

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