Hydrogen supply systems and hydrogen engine vehicles

Abstract

To stably supply hydrogen gas to a hydrogen engine and to suppress the amount of energy consumed by a hydrogen supply device.SOLUTION: A hydrogen supply device 30 comprises a liquid hydrogen pump 32 that boosts the pressure of liquid hydrogen stored in a liquid hydrogen tank 31, a vaporizer 37 that converts the liquid hydrogen discharged from the liquid hydrogen pump 32 into hydrogen gas, a pressure chamber 45 in which the hydrogen gas flowing out from the vaporizer 37 is filled and that supplies the filled hydrogen gas to a hydrogen engine 10, and a pump control unit 80. The pump control unit 80 regulates a discharge flow rate from the liquid hydrogen pump 32 on the basis of the hydrogen flow rate supplied to the hydrogen engine 10, the actual pressure in the pressure chamber 45, and the rotation speed of the hydrogen engine 10 so that the actual pressure in the pressure chamber 45 becomes a target pressure, and changes the target pressure of the pressure chamber 45 according to the rotation speed of the hydrogen engine 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to the structure of a hydrogen supply device that supplies hydrogen gas to a hydrogen engine and the structure of a hydrogen engine vehicle equipped with the hydrogen supply device.

Background Art

[0002] Patent Document 1 discloses a hydrogen supply device including a liquid hydrogen tank, a hydrogen pump, an evaporator, and a pressure hydrogen tank. This hydrogen supply device pressurizes the liquid hydrogen stored in the liquid hydrogen tank with the hydrogen pump, vaporizes it in the evaporator, stores hydrogen gas in the pressure hydrogen tank, and supplies the hydrogen gas stored in the pressure hydrogen tank to a fuel cell.

[0003] Further, Patent Document 2 discloses a liquefied gas vaporizer that vaporizes liquid hydrogen using a heat exchanger using helium gas and supplies it to equipment such as a gas turbine.

[0004] Further, Patent Document 3 discloses an engine that burns hydrogen gas vaporized in a heat exchanger and air in a combustion chamber disposed outside a cylinder, and causes the combustion gas to flow into the cylinder to drive a piston.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, hydrogen engine vehicles, equipped with hydrogen engines that directly burn hydrogen gas instead of gasoline, have been used. Many hydrogen engine vehicles supply hydrogen gas to the hydrogen engine after depressurizing high-pressure hydrogen gas stored in a hydrogen gas tank. However, the capacity of hydrogen gas that can be stored in a hydrogen gas tank is not very large, which has resulted in a short driving range for hydrogen engine vehicles. For this reason, a method is being considered in which liquid hydrogen stored in a liquid hydrogen tank is vaporized and supplied to the hydrogen engine instead of using a hydrogen gas tank.

[0007] In this case, since hydrogen engine vehicles run solely on the driving force of the hydrogen engine, the amount of hydrogen gas consumed fluctuates more significantly than in fuel cell vehicles equipped with a fuel cell and a drive battery. For this reason, methods that control the operation of the hydrogen pump by the pressure of a pressurized hydrogen tank, as in the conventional technology described in Patent Document 1, sometimes fail to suppress fluctuations in the pressure of the hydrogen gas supplied to the hydrogen engine.

[0008] Furthermore, the required supply pressure to a hydrogen engine decreases as the engine speed decreases and increases as the engine speed increases. Therefore, maintaining the hydrogen gas pressure at the high pressures associated with high engine speeds to suppress pressure fluctuations increases the energy consumption of the hydrogen supply system. In addition, the constant high pressure applied to the hydrogen engine increases the required strength, which may lead to an increase in the weight of the hydrogen engine.

[0009] Therefore, this disclosure aims to stably supply hydrogen gas to a hydrogen engine while suppressing the energy consumption of the hydrogen supply device. [Means for solving the problem]

[0010] The hydrogen supply system of this disclosure comprises a liquid hydrogen pump for pressurizing liquid hydrogen stored in a liquid hydrogen tank, a vaporizer for converting the liquid hydrogen discharged from the liquid hydrogen pump into hydrogen gas, a pressure chamber filled with the hydrogen gas flowing out of the vaporizer and for supplying the filled hydrogen gas to a hydrogen engine, and a pump control unit for adjusting the discharge flow rate of the liquid hydrogen pump, wherein the pump control unit adjusts the discharge flow rate of the liquid hydrogen pump so that the actual pressure in the pressure chamber becomes a target pressure based on the hydrogen flow rate supplied to the hydrogen engine, the actual pressure in the pressure chamber, and the rotational speed of the hydrogen engine, and changes the target pressure in the pressure chamber according to the rotational speed of the hydrogen engine. The pump control unit changes the target pressure in the pressure chamber so that when the rotational speed of the hydrogen engine is low, the target pressure in the pressure chamber is lower than when the rotational speed of the hydrogen engine is high; the pump control unit sets the target pressure in the pressure chamber to a first set pressure when the rotational speed of the hydrogen engine is at idle speed; sets the target pressure in the pressure chamber to a second set pressure higher than the first set pressure when the rotational speed of the hydrogen engine is higher than the idle speed; sets the target pressure in the pressure chamber to a third set pressure higher than the first set pressure and less than or equal to the second set pressure when the hydrogen engine stops; and stops the liquid hydrogen pump when the actual pressure in the pressure chamber reaches the third set pressure. child and It is characterized by.

[0011] In this way, the discharge flow rate of the liquid hydrogen pump is adjusted so that the actual pressure in the pressure chamber becomes the target pressure based on the hydrogen flow rate supplied to the hydrogen engine, the actual pressure in the pressure chamber, and the rotational speed of the hydrogen engine. Furthermore, the target pressure in the pressure chamber is changed according to the rotational speed of the hydrogen engine. This allows for a stable supply of hydrogen gas to the hydrogen engine while suppressing the energy consumption of the hydrogen supply device. Along with, There is no need to maintain the pressure in the pressure chamber at a high pressure level corresponding to the high rotational speed of the hydrogen engine, This reduces the energy consumption of the hydrogen supply device. Furthermore, since high-pressure hydrogen gas is stored in the pressure chamber when the hydrogen engine is stopped, the next start-up of the hydrogen engine becomes easier.

[0016] The hydrogen engine vehicle of this disclosure is a hydrogen engine vehicle comprising a hydrogen engine for driving the vehicle and a hydrogen supply device for supplying hydrogen gas to the hydrogen engine, wherein the hydrogen supply device includes a liquid hydrogen pump for pressurizing liquid hydrogen stored in a liquid hydrogen tank, a vaporizer for converting the liquid hydrogen discharged from the liquid hydrogen pump into hydrogen gas, a pressure chamber filled with the hydrogen gas flowing out of the vaporizer and for supplying the filled hydrogen gas to the hydrogen engine, and a pump control unit for adjusting the discharge flow rate of the liquid hydrogen pump, wherein the pump control unit changes the target pressure of the pressure chamber so that when the rotational speed of the hydrogen engine is low, the target pressure of the pressure chamber is lower than when the rotational speed of the hydrogen engine is high, and adjusts the discharge flow rate of the liquid hydrogen pump so that the actual pressure of the pressure chamber becomes the target pressure based on the hydrogen flow rate supplied to the hydrogen engine, the actual pressure of the pressure chamber, and the rotational speed of the hydrogen engine. The pump control unit sets the target pressure in the pressure chamber to a first set pressure when the hydrogen engine is rotating at idle speed, sets the target pressure in the pressure chamber to a second set pressure higher than the first set pressure when the hydrogen engine is rotating at a set speed higher than the idle speed, sets the target pressure in the pressure chamber to a third set pressure higher than the first set pressure and less than or equal to the second set pressure when the hydrogen engine stops, and stops the liquid hydrogen pump when the actual pressure in the pressure chamber reaches the third set pressure. do 、 thing of It is characterized by. [Effects of the Invention]

[0018] This disclosure enables a stable supply of hydrogen gas to a hydrogen engine while suppressing the energy consumption of the hydrogen supply device. [Brief explanation of the drawing]

[0019] [Figure 1] This is a system diagram showing the configuration of a hydrogen engine vehicle according to an embodiment. [Figure 2] Figure 1 shows a functional block diagram of the engine control unit and pump control unit of the hydrogen engine vehicle. [Figure 3] Figure 2 is a map showing the change in the set pressure in the pressure chamber as a function of the rotational speed of the hydrogen engine, stored in the target pressure setting unit. [Figure 4] This flowchart shows the operation of the pump control unit when the hydrogen engine is shut down. [Figure 5] This is a system diagram showing the configuration of the hydrogen supply device according to the embodiment. [Figure 6] It is a functional block diagram of the pump control unit of the hydrogen supply device shown in FIG. 5.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the hydrogen engine vehicle 100 according to the embodiment will be described with reference to the drawings. As shown in FIG. 1, the hydrogen engine vehicle 100 includes a hydrogen engine 10 for driving the vehicle and a hydrogen supply device 30. In FIGS. 1 and 5, thick solid lines indicate liquid flow paths, and double lines indicate gas flow paths. Also, the dashed-dotted line indicates the signal flow.

[0021] As shown in FIG. 1, the hydrogen engine 10 is a reciprocating internal combustion engine including a plurality of cylinders 11 and pistons 12 that move up and down within the cylinders 11, and has the same structure as a gasoline engine. In FIG. 1, only one of the plurality of cylinders 11 is illustrated. An intake port 13 through which air flows into the interior of the cylinder 11 and an exhaust port 14 for discharging combustion gas within the cylinder 11 are provided at the upper portion of the cylinder 11. An intake valve 15 and an exhaust valve 16 are respectively attached to the intake port 13 and the exhaust port 14. An injector 17 for injecting hydrogen gas into the cylinder 11 is attached above the side surface of the cylinder 11. A hydrogen gas introduction pipe 23 for introducing hydrogen gas supplied from the hydrogen supply device 30 is connected to the injector 17. The hydrogen gas supplied from the hydrogen gas introduction pipe 23 is injected from the injector 17 into the interior of the cylinder 11 and burns inside the cylinder 11. The combustion gas moves the piston 12 up and down to rotate a crankshaft (not shown) connected to the lower end of the piston 12.

[0022] The hydrogen engine vehicle 100 is equipped with an accelerator 19, a throttle position sensor 20, a flow rate sensor 22, a rotational speed sensor 24, a start switch 25, and an engine control unit 70. The throttle position sensor 20 detects the throttle position of the accelerator 19. The throttle position signal detected by the throttle position sensor 20 is input to the engine control unit 70. Further, a flow rate sensor 22 for detecting the actual flow rate of the hydrogen gas flowing into the hydrogen engine 10 is attached to the hydrogen gas introduction pipe 23. The signal of the actual flow rate detected by the flow rate sensor 22 is input to the engine control unit 70. The rotational speed sensor 24 detects the rotational speed of the hydrogen engine 10. The rotational speed of the hydrogen engine 10 detected by the rotational speed sensor 24 is input to the engine control unit 70. Also, the hydrogen engine vehicle 100 is equipped with a cooling water pump 18 for circulating cooling water through the hydrogen engine 10. The cooling water pump 18 operates according to the command of the engine control unit 70. When the start switch 25 is turned on, the hydrogen engine 10 starts, and when the start switch 25 is turned off, the hydrogen engine 10 stops.

[0023] The engine control unit 70 adjusts the hydrogen flow rate supplied to the hydrogen engine 10. As shown in FIG. 1, the engine control unit 70 is a computer including a CPU 71 which is a processor for performing information processing therein and a memory 72 for storing programs and control data. The engine control unit 70 calculates the target flow rate of the hydrogen gas to be supplied to the hydrogen engine 10 based on the throttle position of the accelerator 19 detected by the throttle position sensor 20 and the rotational speed of the hydrogen engine 10 input from the rotational speed sensor 24, and adjusts the operation of the injector 17 to adjust the flow rate of the hydrogen gas to the hydrogen engine 10. Also, the engine control unit 70 adjusts the operation of the cooling water pump 18. Details of the configuration of the engine control unit 70 will be described later.

[0024] The hydrogen supply device 30 pressurizes and vaporizes the liquid hydrogen stored in the liquid hydrogen tank 31 and supplies it to the hydrogen engine 10 as hydrogen gas at supply pressure. The hydrogen supply device 30 comprises a liquid hydrogen tank 31, a liquid hydrogen pump 32, a vaporizer 37, a pressure chamber 45, a pressure reducing valve 50, a heater 65, and a pump control unit 80. When the start switch 25 is turned on, the hydrogen supply device 30 starts, and when the start switch 25 is turned off, the hydrogen supply device 30 stops.

[0025] The liquid hydrogen tank 31 is an insulated container that stores cooled liquid hydrogen inside. The pressure inside the liquid hydrogen tank 31 is approximately the same as atmospheric pressure or slightly higher than atmospheric pressure.

[0026] The liquid hydrogen pump 32 is a reciprocating pump in which an in-tank piston 33, located inside the liquid hydrogen tank 31, moves up and down. The liquid hydrogen pump 32 increases the pressure of the liquid hydrogen stored in the liquid hydrogen tank 31 to a pressure higher than the supply pressure of the hydrogen gas supplied to the hydrogen engine 10. A motor 35 and a drive cam 34, which converts the rotational motion of the motor 35 into vertical reciprocating motion, are located outside the liquid hydrogen tank 31. The casing of the in-tank piston 33 has an intake port for drawing in liquid hydrogen and an outlet port for discharging liquid hydrogen, and a liquid hydrogen discharge pipe 36 is connected to the outlet port. The liquid hydrogen discharge pipe 36 extends from inside the liquid hydrogen tank 31 to outside the liquid hydrogen tank 31 and is connected to a vaporizer 37. When the motor 35 rotates, the drive cam 34 causes the in-tank piston 33 to reciprocate vertically, increasing the pressure of the liquid hydrogen stored in the liquid hydrogen tank 31 and discharging it from the liquid hydrogen discharge pipe 36 to the vaporizer 37.

[0027] The vaporizer 37 is a heat exchanger between high-pressure liquid hydrogen discharged from the liquid hydrogen pump 32 and heated helium gas, vaporizing the liquid hydrogen to produce high-pressure hydrogen gas. The vaporizer 37 consists of a casing 61 through which heated helium gas flows, and a tube 62 installed inside the casing 61 through which high-pressure liquid hydrogen flows.

[0028] The heater 65 is a heat exchanger between the helium gas that has passed through the vaporizer 37 and the cooling water of the hydrogen engine 10, and it heats the helium gas whose temperature has decreased after passing through the vaporizer 37. The heater 65 consists of a casing 66 through which the helium gas flows and a tube 67 installed inside the casing 66 through which the cooling water of the hydrogen engine 10 flows.

[0029] The casing 61 of the vaporizer 37 and the casing 66 of the heater 65 are connected by a heating gas duct 63 and a return duct 64. A fan 52 is attached to the heating gas duct 63, and when the fan 52 is driven, helium gas circulates between the casing 66 of the heater 65 and the casing 61 of the vaporizer 37. The fan 52 is driven by a command from the pump control unit 80, which will be described later. In addition, the cooling water for the hydrogen engine 10 is pressurized by the cooling water pump 18 and circulates between the hydrogen engine 10 and the tube 67 of the heater 65 through a supply pipe 68 and a return pipe 69. The cooling water pump 18 is operated by a command from the engine control unit 70.

[0030] The high-temperature cooling water of the hydrogen engine 10 flows through the tube 67 of the heater 65, heating the helium gas. The heated helium gas flows from the heating gas duct 63 into the casing 61 of the vaporizer 37, where it exchanges heat with the high-pressure, low-temperature liquid hydrogen that flows from the liquid hydrogen discharge pipe 36 into the tube 62 of the vaporizer 37. Through heat exchange, the liquid hydrogen is heated and vaporizes, becoming high-pressure hydrogen gas which flows out into the high-pressure hydrogen gas supply pipe 38.

[0031] A pressure chamber 45 is connected to the high-pressure hydrogen gas supply pipe 38 via a hydrogen gas filling pipe 39 and a hydrogen gas outlet pipe 41. The hydrogen gas outlet pipe 41 is connected downstream of the hydrogen gas filling pipe 39. A check valve 40 is installed on the hydrogen gas filling pipe 39. A gate valve 42 is installed on the hydrogen gas outlet pipe 41. A pressure sensor 46 is installed on the pressure chamber 45 to detect the actual pressure in the pressure chamber 45. The capacity of the pressure chamber 45 is the capacity for 30 to 60 seconds of the maximum hydrogen consumption flow rate of the hydrogen engine 10. This suppresses sudden fluctuations in the pressure of the pressure chamber 45 even if the hydrogen consumption of the hydrogen engine 10 fluctuates rapidly.

[0032] If the hydrogen pressure in the high-pressure hydrogen gas supply pipe 38 is higher than the hydrogen pressure in the pressure chamber 45, the check valve 40 opens and hydrogen gas is filled into the pressure chamber 45 from the hydrogen gas filling pipe 39. On the other hand, if the hydrogen pressure in the high-pressure hydrogen gas supply pipe 38 is lower than the hydrogen pressure in the pressure chamber 45, the hydrogen gas filled into the pressure chamber 45 flows out into the high-pressure hydrogen gas supply pipe 38 through the hydrogen gas outlet pipe 41 and the gate valve 42. The gate valve 42 is opened and closed by a command from the pump control unit 80, which will be explained later.

[0033] Downstream of the hydrogen gas outlet pipe 41 of the high-pressure hydrogen gas supply pipe 38, a pressure reducing valve 50 is provided to reduce the high-pressure hydrogen gas to the supply pressure. The pressure reducing valve 50 is operated by a command from the pump control unit 80, which will be described later. The hydrogen gas, reduced to the supply pressure by the pressure reducing valve 50, flows out into the hydrogen gas supply pipe 53 connected downstream of the pressure reducing valve 50. A pressure sensor 51 for detecting the hydrogen gas supply pressure is attached to the hydrogen gas supply pipe 53. The hydrogen gas supply pipe 53 is connected to the hydrogen gas inlet pipe 23 and supplies hydrogen gas to the injector 17 of the hydrogen engine 10.

[0034] The pump control unit 80 is a computer equipped with a CPU 81, which is a processor that performs information processing, and a memory 82 that stores programs and control data. The pump control unit 80 is connected to the engine control unit 70, and receives data from the engine control unit 70. The pump control unit 80 also receives a signal of the actual pressure in the pressure chamber 45 detected by the pressure sensor 46.

[0035] The pump control unit 80 adjusts the pressure reducing valve 50 so that the hydrogen gas pressure detected by the pressure sensor 51 becomes a predetermined supply pressure. The pump control unit 80 also adjusts the operation of the fan 52. Furthermore, the pump control unit 80 adjusts the discharge flow rate of the liquid hydrogen pump 32 so that the actual pressure in the pressure chamber 45 becomes the target pressure, based on the hydrogen flow rate supplied to the hydrogen engine 10, the actual pressure in the pressure chamber 45 detected by the pressure sensor 46, and the rotational speed of the hydrogen engine 10 detected by the rotational speed sensor 24, and also changes the target pressure in the pressure chamber 45 according to the rotational speed of the hydrogen engine 10.

[0036] Next, we will describe the details of the engine control unit 70 and the pump control unit 80 with reference to Figure 2.

[0037] The engine control unit 70 comprises two functional blocks: a target flow rate calculation unit 75 and an injector PID control unit 76. Each functional block can be realized by the CPU 71 executing a program stored in the memory 72.

[0038] The target flow rate calculation unit 75 of the engine control unit 70 calculates the target flow rate of hydrogen gas supplied to the hydrogen engine 10 based on the opening degree of the accelerator 19 input from the opening degree sensor 20 and the rotational speed of the hydrogen engine 10 input from the rotational speed sensor 24. The target flow rate may be calculated, for example, as a flow rate proportional to the opening degree of the accelerator 19, or a map of the opening degree, rotational speed, and target flow rate may be stored in the memory 72 and calculated by referring to the map. In addition to the opening degree of the accelerator 19 and the rotational speed of the hydrogen engine 10, the target flow rate may also be calculated considering, for example, the speed of the hydrogen engine vehicle 100. The target flow rate calculation unit 75 outputs the calculated target flow rate to the injector PID control unit 76 and also to the pump PID control unit 86 of the pump control unit 80. Furthermore, the target flow rate calculation unit 75 outputs the rotational speed of the hydrogen engine 10 to the target pressure setting unit 89 of the pump control unit 80.

[0039] The injector PID control unit 76 calculates an injector drive command using PID control based on the difference between the target flow rate of hydrogen gas input from the target flow rate calculation unit 75 and the actual flow rate of hydrogen gas detected by the flow rate sensor 22, and outputs it to the injector 17. The injector 17 operates according to the drive command from the injector PID control unit 76. The injector PID control unit 76 also outputs the actual flow rate of hydrogen gas input from the flow rate sensor 22 to the pump PID control unit 86 of the pump control unit 80.

[0040] The pump control unit 80 comprises four functional blocks: a pressure feedback control unit 85, a pump PID control unit 86, an adder 87, and a target pressure setting unit 89. Each functional block is realized by the CPU 81 executing a program stored in memory 82.

[0041] The hydrogen supply device 30 only needs to generate hydrogen gas at the same flow rate as the actual flow rate of hydrogen gas consumed by the hydrogen engine 10. Since the amount of hydrogen gas generated is proportional to the flow rate of liquid hydrogen discharged from the liquid hydrogen pump 32, the flow rate of liquid hydrogen discharged from the liquid hydrogen pump 32 should be controlled to a flow rate proportional to the actual flow rate of hydrogen gas consumed by the hydrogen engine 10. However, if the flow rate of hydrogen gas generated by the hydrogen supply device 30 is less than the flow rate of hydrogen gas consumed by the hydrogen engine 10, the actual pressure in the pressure chamber 45 will decrease. Conversely, if the flow rate of hydrogen gas generated by the hydrogen supply device 30 is greater than the flow rate of hydrogen gas consumed by the hydrogen engine 10, the actual pressure in the pressure chamber 45 will increase. When the actual pressure in the pressure chamber 45 fluctuates, the hydrogen gas supply pressure downstream of the pressure reducing valve 50 fluctuates. Also, if the actual pressure in the pressure chamber 45 falls below the supply pressure, hydrogen gas cannot be supplied to the hydrogen engine 10.

[0042] Therefore, the pump control unit 80 calculates a PID command value using the pump PID control unit 86 to adjust the rotation speed of the motor 35 of the liquid hydrogen pump 32 so that the flow rate of liquid hydrogen discharged from the liquid hydrogen pump 32 corresponds to the flow rate of hydrogen gas supplied to the hydrogen engine 10. In addition, the pressure feedback control unit 85 calculates a pressure feedback command value to adjust the rotation speed of the motor 35 of the liquid hydrogen pump 32 so that the actual pressure in the pressure chamber 45 becomes the target pressure. Then, the adder 87 adds the PID command value and the pressure feedback command value to generate a motor rotation speed command and adjust the rotation speed of the motor 35. As a result, hydrogen gas is supplied to the hydrogen engine 10 in a manner that matches the flow rate of hydrogen gas consumed by the hydrogen engine 10, and the actual pressure in the pressure chamber 45 is adjusted to the target pressure, enabling a stable supply of hydrogen gas to the hydrogen engine 10.

[0043] Furthermore, the pump control unit 80 changes the target pressure of the pressure chamber 45 so that when the rotational speed of the hydrogen engine 10 is low, the target pressure of the pressure chamber 45 is lower than when the rotational speed of the hydrogen engine 10 is high. This eliminates the need to constantly maintain the pressure in the pressure chamber 45 in a high-pressure state corresponding to high rotational speeds, thereby reducing the energy consumption of the hydrogen supply device 30. The details of the pump control unit 80 will be described below.

[0044] The pump PID control unit 86 outputs a PID command value for the rotational speed of the motor 35 of the liquid hydrogen pump 32 based on the difference between the target flow rate and the actual flow rate of hydrogen gas input from the engine control unit 70. Since this PID command value is calculated based on the same difference between the target value and the actual flow rate of hydrogen gas as the injector PID control unit 76, it becomes a command value synchronized with the injector drive command. Therefore, the PID command value can make the flow rate of liquid hydrogen discharged from the liquid hydrogen pump 32 correspond to the flow rate of hydrogen gas supplied to the hydrogen engine 10.

[0045] The target pressure setting unit 89 sets the target pressure in the pressure chamber 45 based on the rotational speed of the hydrogen engine 10 input from the engine control unit 70 and outputs it to the pressure feedback control unit 85. The target pressure setting unit 89 internally stores a map 90 of target pressures for different rotational speeds of the hydrogen engine 10, as shown in Figure 3. It then refers to the map 90 and outputs the target pressure corresponding to the input rotational speed of the hydrogen engine 10.

[0046] Now, let's explain the map 90 shown in Figure 3. In Figure 3, R1 represents the idling speed R1 of the hydrogen engine 10. R3 represents the maximum rotational speed R3 of the hydrogen engine 10. R2 represents the set rotational speed R2, which is set between the idling speed R1 and the maximum rotational speed R3. The set rotational speed R2 may be set, for example, as an intermediate value between the idling speed R1 and the maximum rotational speed R3. As shown in Figure 3, when the rotational speed of the hydrogen engine 10 is at the idling speed R1, the target pressure becomes the lowest first set pressure P1. When the rotational speed of the hydrogen engine 10 is higher than the set rotational speed R2, the target pressure becomes the second set pressure P2. When the rotational speed of the hydrogen engine 10 is between the idling speed R1 and the set rotational speed R2, the target pressure increases as the rotational speed of the hydrogen engine 10 increases. The first set pressure P1 is slightly higher than the required supply pressure to the hydrogen engine 10 when the hydrogen engine 10 is at idle speed R1. The second set pressure P2 is slightly higher than the supply pressure to the hydrogen engine 10 when the hydrogen engine 10 is at maximum speed R3. For example, the first set pressure P1 and the second set pressure P2 may be about 10% higher than the required supply pressure to the hydrogen engine 10 in each state.

[0047] The pressure feedback control unit 85 outputs a pressure feedback control command value based on the difference between the target pressure input from the target pressure setting unit 89 and the actual pressure in the pressure chamber 45 detected by the pressure sensor 46. The pressure feedback command value is a command that increases the rotation speed of the motor 35 of the liquid hydrogen pump 32 to increase the discharge flow rate when the actual pressure in the pressure chamber 45 is lower than the target pressure, and conversely decreases the rotation speed of the motor 35 of the liquid hydrogen pump 32 to decrease the discharge flow rate when the actual pressure in the pressure chamber 45 is higher than the target pressure.

[0048] The adder 87 generates a rotational speed command for the motor 35 by adding the PID command value and the pressure feedback command value. When adding the two command values, they may be simply added together or added with weights. For example, if the hydrogen consumption of the hydrogen engine 10 does not fluctuate much, the weight of the pressure feedback command value may be made greater than the weight of the PID command value. Conversely, if the hydrogen consumption of the hydrogen engine 10 fluctuates greatly, the weight of the PID command value may be increased to improve responsiveness.

[0049] Next, we will explain how to control the rotational speed of the motor 35 of the pump control unit 80 configured in this way.

[0050] When the hydrogen engine 10 is rotating at idle speed R1, the pump control unit 80 sets the target pressure to the lowest first set pressure P1 and drives the motor 35 at a low rotational speed. When the accelerator 19 is pressed and the flow rate of hydrogen gas supplied to the hydrogen engine 10 increases, the pump control unit 80 increases the rotational speed of the motor 35 by an amount corresponding to the increase in the hydrogen gas flow rate. Furthermore, when the rotational speed of the hydrogen engine 10 increases due to the pressing of the accelerator 19, the pump control unit 80 refers to the map 90 shown in Figure 3 and increases the target pressure of the pressure chamber 45. Then, the pump control unit 80 increases the rotational speed of the motor 35 by an amount corresponding to the increase in the hydrogen gas flow rate, as well as an amount to increase the actual pressure in the pressure chamber 45.

[0051] Conversely, when the accelerator pedal 19 is no longer pressed, the hydrogen gas flow rate decreases, and the rotational speed of the hydrogen engine 10 drops from the set rotational speed R2 to the idling rotational speed R1. In this case, the pump control unit 80 reduces the rotational speed of the motor 35 by an amount that corresponds to the decrease in the hydrogen gas flow rate, as well as by an amount that reduces the actual pressure in the pressure chamber 45.

[0052] In this way, the PID command value and the pressure feedback command value are added together to generate a rotation speed command for the motor 35, and the rotation speed of the motor 35 of the liquid hydrogen pump 32 is adjusted to adjust the discharge flow rate of the liquid hydrogen pump 32. As a result, hydrogen gas is supplied to the hydrogen engine 10 in a manner that matches the flow rate of hydrogen gas consumed by the hydrogen engine 10, and the actual pressure in the pressure chamber 45 is set as the target pressure, enabling a stable supply of hydrogen gas to the hydrogen engine 10. Furthermore, since the pressure in the pressure chamber 45 is changed according to the rotation speed of the hydrogen engine 10, it is not necessary to maintain the pressure in the pressure chamber 45 in a high-pressure state corresponding to the high rotation speed of the hydrogen engine 10, and the energy consumption of the hydrogen supply device 30 can be reduced.

[0053] Next, with reference to Figure 4, the operation of the pump control unit 80 when the hydrogen engine vehicle 100 stops will be explained. When the rotational speed of the hydrogen engine 10 is the idling speed R1, the pump control unit 80 adjusts the rotational speed of the motor 35 of the liquid hydrogen pump 32 so that the actual pressure in the pressure chamber 45 becomes the first set pressure P1.

[0054] If the start switch 25 is turned off in this state, the pump control unit 80 determines YES in step S101 in Figure 4 and proceeds to step S102 in Figure 4. The pump control unit 80 then sets the set pressure of the pressure chamber 45 to a third set pressure P3 that is higher than the first set pressure P1 and less than or equal to the second set pressure P2. Here, the third set pressure P3 may be set to the same pressure as the second set pressure P2.

[0055] As a result, the rotational speed of the motor 35 increases, and the actual pressure in the pressure chamber 45 increases accordingly. Immediately after the hydrogen engine 10 is stopped, the temperature of the cooling water in the hydrogen engine 10 is high, so the liquid hydrogen that flows from the liquid hydrogen pump 32 into the vaporizer 37 is vaporized into hydrogen gas. In step S103 of Figure 4, the pump control unit 80 waits until the actual pressure in the pressure chamber 45 reaches the third set pressure P3. If the pump control unit 80 determines YES in step S103 of Figure 4, it proceeds to step S104 of Figure 4 to stop the motor 35 of the liquid hydrogen pump 32, and in step S105 of Figure 4 to close the gate valve 42.

[0056] This allows high-pressure hydrogen gas to be stored in the pressure chamber 45 when the hydrogen engine 10 is stopped, making it easier to start the hydrogen engine 10 again.

[0057] Furthermore, if the actual pressure in the pressure chamber 45 is higher than the third set pressure P3 when the start switch 25 is turned off, the pump control unit 80 may stop the motor 35 of the liquid hydrogen pump 32 and close the gate valve 42 without changing the target pressure setting.

[0058] In the above explanation, it was assumed that the pump control unit 80 receives the target flow rate of hydrogen gas, the actual flow rate of hydrogen gas detected by the flow sensor 22, and the rotational speed of the hydrogen engine 10 from the engine control unit 70, but this is not limited to this configuration. For example, the pump control unit 80 may be configured to receive signals of the actual flow rate of hydrogen gas and the rotational speed directly from the flow sensor 22 and the rotational speed sensor 24 without going through the engine control unit 70.

[0059] Furthermore, although the above description has assumed that the pump control unit 80 includes a pump PID control unit 86 that outputs a PID command value for the rotational speed of the motor 35 of the liquid hydrogen pump 32 based on the difference between the target flow rate and the actual flow rate of hydrogen gas input from the engine control unit 70, the system is not limited to this configuration. For example, based on one input from the engine control unit 70, either the target flow rate or the actual flow rate of hydrogen gas, a proportional command value may be calculated by proportional control, as shown in the hydrogen supply device 130 in Figures 5 and 6, and a rotational speed command for the motor 35 may be generated using this value and a pressure feedback command value.

[0060] Next, with reference to Figures 5 and 6, we will describe a hydrogen supply device 130 with a different configuration from the hydrogen supply device 30 described earlier. Parts identical to those in the hydrogen supply device 30 described earlier are denoted by the same reference numerals, and their descriptions are omitted.

[0061] As shown in Figure 5, the hydrogen supply device 130 is equipped with a flow sensor 92 attached to the hydrogen gas supply pipe 53 to detect the flow rate of hydrogen gas supplied to the hydrogen engine 10. The flow rate signal detected by the flow sensor 92 and the signal from the rotation speed sensor 24 are input to the pump control unit 180. The pump control unit 180 is a computer equipped with a CPU 181, which is a processor that performs information processing, and a memory 182 that stores programs and control data. Unlike the pump control unit 80 of the hydrogen supply device 30 of the embodiment described earlier, the pump control unit 180 is not connected to the engine control unit 70.

[0062] As shown in Figure 6, the pump control unit 180 is equipped with a pump proportional control unit 88 instead of the pump PID control unit 86 of the pump control unit 80 described earlier. The pump proportional control unit 88 calculates a proportional command value by multiplying the actual flow rate of hydrogen gas detected by the flow sensor 92 by a proportionality constant. Based on the proportional command value, the hydrogen supply device 130 can generate hydrogen gas in conjunction with fluctuations in the flow rate of hydrogen gas consumed by the hydrogen engine 10, and can adjust the actual pressure in the pressure chamber 45 to a target pressure, similar to the hydrogen supply device 30 described earlier. [Explanation of Symbols]

[0063] 10 Hydrogen engine, 11 Cylinder, 12 Piston, 13 Intake port, 14 Exhaust port, 15 Intake valve, 16 Exhaust valve, 17 Injector, 18 Cooling water pump, 19 Accelerator, 20 Opening sensor, 22, 92 Flow sensor, 23 Hydrogen gas inlet pipe, 24 Rotation speed sensor, 30, 130 Hydrogen supply device, 31 Liquid hydrogen tank, 32 Liquid hydrogen pump, 33 In-tank piston, 34 Drive cam, 35 Motor, 36 Liquid hydrogen discharge pipe, 37 Vaporizer, 38 High-pressure hydrogen gas supply pipe, 39 Hydrogen gas filling pipe, 40 Check valve, 41 Hydrogen gas outlet pipe, 42 Gate valve, 45 Pressure chamber, 46 Pressure sensor, 50 Pressure reducing valve, 51 Pressure sensor, 52 Fan, 53 Hydrogen gas supply pipe, 61, 66 Casing, 62, 67 Tube, 63 64 Heating gas duct, 65 Return duct, 68 Heater, 69 Supply pipe, 70 Engine control unit, 71, 81, 181 CPU, 72, 82, 182 Memory, 75 Target flow rate calculation unit, 76 Injector PID control unit, 80, 180 Pump control unit, 85 Pressure feedback control unit, 86 Pump PID control unit, 87 Adder, 88 Pump proportional control unit, 89 Target pressure setting unit, 100 Hydrogen engine vehicle.

Claims

1. A hydrogen supply device, A liquid hydrogen pump that pressurizes the liquid hydrogen stored in the liquid hydrogen tank, A vaporizer that converts the liquid hydrogen discharged from the aforementioned liquid hydrogen pump into hydrogen gas, A pressure chamber is filled with hydrogen gas that has leaked out of the aforementioned vaporizer, and the filled hydrogen gas is supplied to the hydrogen engine. The system includes a pump control unit that adjusts the discharge flow rate of the liquid hydrogen pump, The pump control unit adjusts the discharge flow rate of the liquid hydrogen pump so that the actual pressure in the pressure chamber becomes the target pressure, based on the hydrogen flow rate supplied to the hydrogen engine, the actual pressure in the pressure chamber, and the rotational speed of the hydrogen engine, and also changes the target pressure in the pressure chamber according to the rotational speed of the hydrogen engine. The pump control unit changes the target pressure in the pressure chamber so that when the rotational speed of the hydrogen engine is low, the target pressure in the pressure chamber is lower than when the rotational speed of the hydrogen engine is high. The pump control unit sets the target pressure in the pressure chamber to a first set pressure when the hydrogen engine is rotating at idle speed, sets the target pressure in the pressure chamber to a second set pressure higher than the first set pressure when the hydrogen engine is rotating at a set speed higher than the idle speed, sets the target pressure in the pressure chamber to a third set pressure higher than the first set pressure and less than or equal to the second set pressure when the hydrogen engine stops, and stops the liquid hydrogen pump when the actual pressure in the pressure chamber reaches the third set pressure. A hydrogen supply device characterized by the following features.

2. Hydrogen engines for vehicle propulsion, A hydrogen engine vehicle comprising a hydrogen supply device that supplies hydrogen gas to the hydrogen engine, The hydrogen supply device is A liquid hydrogen pump that pressurizes the liquid hydrogen stored in the liquid hydrogen tank, A vaporizer that converts the liquid hydrogen discharged from the aforementioned liquid hydrogen pump into hydrogen gas, A pressure chamber is filled with hydrogen gas that has leaked out of the vaporizer and supplies the filled hydrogen gas to the hydrogen engine, The pump control unit includes a pump control unit that adjusts the discharge flow rate of the liquid hydrogen pump, The pump control unit changes the target pressure in the pressure chamber so that when the rotational speed of the hydrogen engine is low, the target pressure in the pressure chamber is lower than when the rotational speed of the hydrogen engine is high, and adjusts the discharge flow rate of the liquid hydrogen pump so that the actual pressure in the pressure chamber becomes the target pressure based on the hydrogen flow rate supplied to the hydrogen engine, the actual pressure in the pressure chamber, and the rotational speed of the hydrogen engine. The pump control unit sets the target pressure in the pressure chamber to a first set pressure when the hydrogen engine is rotating at idle speed, sets the target pressure in the pressure chamber to a second set pressure higher than the first set pressure when the hydrogen engine is rotating at a set speed higher than the idle speed, sets the target pressure in the pressure chamber to a third set pressure higher than the first set pressure and less than or equal to the second set pressure when the hydrogen engine stops, and stops the liquid hydrogen pump when the actual pressure in the pressure chamber reaches the third set pressure. A hydrogen engine vehicle characterized by the following features.

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