JP2021026948A - Fuel gas-supply unit - Google Patents

Abstract

To increase the rate of filling a second fuel tank lower than a first fuel tank in heat dissipation property when filling a fuel gas.SOLUTION: A fuel gas-supply unit comprises: two fuel tanks for storing a hydrogen gas; a first main stop valve for switching fuel gas supply from the first fuel tank to a fuel cell stack and shutoff of the supply; a second main stop valve for switching fuel gas supply from the second fuel tank to the fuel cell stack and shutoff of the supply; and FCECU. The two fuel tanks include: a first fuel tank; and a second fuel tank lower than the first fuel tank in heat dissipation property. FCECU controls the first and second main stop valves in such a way that an internal pressure of the first fuel tank is lower than an internal pressure of the second fuel tank when the fuel cell stack generates electric power.SELECTED DRAWING: Figure 2

Description

The present invention relates to a fuel gas supply device.

The fuel cell system includes a fuel cell stack that generates power by a chemical reaction between the fuel gas and the oxidant gas, and a fuel gas supply device that supplies the fuel gas to the fuel cell stack. The fuel gas supply device includes a fuel tank in which fuel gas is stored. The fuel gas supply device supplies fuel gas from the fuel tank to the fuel cell stack when power is generated by the fuel cell stack.

The fuel gas supply device described in Patent Document 1 includes a plurality of fuel tanks, a receptacle, and a filling flow path connecting the receptacle and each fuel tank. The filling flow path branches from the receptacle to each fuel tank. The receptacle is a fuel gas filling port. When the filling rate of the fuel tank decreases, the fuel tank is filled with fuel gas. When the fuel tank is filled with fuel gas, the fuel gas is supplied to the filling flow path from a nozzle attached to the receptacle. The fuel gas is supplied to each fuel tank via the filling flow path, whereby the fuel gas is filled in each fuel tank.

JP-A-2019-96396

When the fuel tank is filled with fuel gas, the temperature of the fuel tank rises. At this time, the temperature of the fuel tank having high heat dissipation is lower than that of the fuel tank having low heat dissipation. Since the fuel gas has a low gas density due to thermal expansion, if the internal pressure of each fuel tank is the same, the fuel tank having high heat dissipation has a higher filling rate than the fuel tank having low heat dissipation. If the fuel gas is filled when the fuel tank with high heat dissipation is fully filled, the fuel tank with low heat dissipation will not be fully filled and the fuel tank with low heat dissipation can be sufficiently filled with fuel gas. It cannot be said that there is.

An object of the present invention is to provide a fuel gas supply device capable of improving the filling rate of a second fuel tank having lower heat dissipation than the first fuel tank when filling the fuel gas.

The fuel gas supply device that solves the above problems is a fuel gas supply device that supplies fuel gas to the fuel cell stack, and includes a first fuel tank in which the fuel gas is stored and a fuel gas in which the fuel gas is stored. A second fuel tank having lower heat dissipation than the first fuel tank, a first main stop valve for switching between supply and cutoff of the fuel gas from the first fuel tank to the fuel cell stack, and the second. It is supplied from a second main stop valve that switches between supply and interruption of the fuel gas from the fuel tank to the fuel cell stack, and a filling device that fills the first fuel tank and the second fuel tank with the fuel gas. The internal pressure of the first fuel tank is the first when the fuel gas is flowing, the filling path is branched from the filling path to the first fuel tank and the second fuel tank, and the fuel cell stack is generating power. (2) The first main stop valve and a pressure control unit that controls the second main stop valve so as to be lower than the internal pressure of the fuel tank are provided.

At the time of power generation of the fuel cell stack, control is performed so that the internal pressure of the first fuel tank is lower than that of the second fuel tank. Therefore, at the time when the filling device starts filling the first fuel tank and the second fuel tank with fuel gas, the internal pressure of the first fuel tank is lower than that of the second fuel tank. The fuel gas supplied from the filling device to the filling path is filled in the first fuel tank and the second fuel tank according to the difference between the internal pressure of the first fuel tank and the internal pressure of the second fuel tank. When the internal pressure of the first fuel tank is lower than the internal pressure of the second fuel tank, the fuel gas is likely to be supplied to the first fuel tank. With the passage of time, the internal pressure of the first fuel tank and the internal pressure of the second fuel tank become the same, so that the internal pressure of the first fuel tank rises more than the internal pressure of the second fuel tank when the fuel gas is filled. .. The temperature of the fuel tank rises more as the internal pressure rises. Therefore, compared to the case where the fuel gas filling is started from the state where the internal pressure of the first fuel tank and the internal pressure of the second fuel tank are the same, the temperature of the first fuel tank and the temperature of the second fuel tank are different when the fuel gas is filled. The difference between the two can be reduced. Since the difference between the filling rate of the first fuel tank and the filling rate of the second fuel tank due to the thermal expansion of the fuel gas can be reduced, the filling rate of the second fuel tank can be improved.

Regarding the fuel gas supply device, the pressure control unit has the first main stop valve and the second main stop valve so that the internal pressure of the first fuel tank is lower than the internal pressure of the second fuel tank by a predetermined value or more. May be controlled. By setting a predetermined value, the difference between the internal pressure of the first fuel tank and the internal pressure of the second fuel tank can be adjusted.

Regarding the fuel gas supply device, the pressure control unit supplies the fuel gas to the fuel cell stack only from the first fuel tank until the internal pressure of the first fuel tank reaches a predetermined threshold value. The first main stop valve and the second main stop valve are controlled so that the fuel gas is supplied from the second fuel tank to the fuel cell stack when the internal pressure of the first fuel tank reaches the threshold value. The first main stop valve and the second main stop valve may be controlled. Since the fuel gas needs to be supplied only from the first fuel tank until the internal pressure of the first fuel tank reaches a predetermined threshold value, the control performed by the pressure control unit can be simplified.

According to the present invention, when filling fuel gas, it is possible to improve the filling rate of the second fuel tank, which has lower heat dissipation than the first fuel tank.

Block diagram showing a fuel cell system. The flowchart which shows the process performed by FCECU. The figure which shows the relationship between the operating time of a vehicle and the internal pressure of each fuel tank. The figure which shows the relationship between the charge differential pressure and the temperature of each fuel tank. The figure which shows the relationship between the time and the internal pressure of each fuel tank when hydrogen gas is filled from the state where the internal pressure of a 1st fuel tank and the internal pressure of a 2nd fuel tank are the same. The figure which shows the relationship between the time and the temperature of each fuel tank when hydrogen gas is filled from the state where the internal pressure of a 1st fuel tank and the internal pressure of a 2nd fuel tank are the same. The figure which shows the relationship between the time and the internal pressure of each fuel tank when hydrogen gas is filled from the state where the internal pressure of a 1st fuel tank is lower than that of a 2nd fuel tank. The figure which shows the relationship between the time and the temperature of each fuel tank when hydrogen gas is filled from the state where the internal pressure of a 1st fuel tank is lower than that of a 2nd fuel tank.

Hereinafter, an embodiment of the fuel gas supply device will be described.
As shown in FIG. 1, the fuel cell system 10 includes a fuel cell stack 11, an air supply system 12 that supplies air to the fuel cell stack 11, and a fuel gas supply device 20 that supplies fuel gas to the fuel cell stack 11. , Equipped with. The fuel cell system 10 of the present embodiment is mounted on a vehicle such as an industrial vehicle or a passenger car. Industrial vehicles are, for example, forklifts and towing tractors. The fuel cell stack 11 is a stack of a plurality of fuel cell cells. The fuel cell is, for example, a polymer electrolyte fuel cell. The fuel cell stack 11 generates electricity by a chemical reaction between the fuel gas and the oxidant gas. In the present embodiment, power generation is performed using hydrogen gas as a fuel gas and oxygen in the air as an oxidant gas.

The fuel cell system 10 is a system that supplies the electric power generated by the fuel cell stack 11 to the load 13. The load 13 is, for example, an in-vehicle electric power device such as a motor for driving a vehicle or an auxiliary machine. The electric power generated by the fuel cell system 10 is supplied to the load 13 via the electric power conversion device. The power converter includes at least one of an inverter and a converter.

The air supply system 12 includes a compressor that compresses and discharges air sucked from the atmosphere, and an intercooler that cools the air discharged from the compressor.
The fuel gas supply device 20 includes two fuel tanks 21, 31 for storing hydrogen gas, a supply flow path 41 for connecting the fuel tanks 21, 31 and the fuel cell stack 11, a receptacle 51, a receptacle 51, and fuel. A filling flow path 52 for connecting the tanks 21 and 31 and an FCECU 61 are provided.

The fuel tanks 21 and 31 include a first fuel tank 21 and a second fuel tank 31. The heat dissipation of the first fuel tank 21 and the second fuel tank 31 is different. The "heat dissipation" is an index indicating the ease with which the temperatures of the two fuel tanks 21 and 31 drop with the passage of time. When the first fuel tank 21 and the second fuel tank 31 are brought to the same tank temperature of room temperature or higher and the same time elapses, the low temperature fuel tanks 21 and 31 dissipate heat as compared with the high temperature fuel tanks 21 and 31. It can be said that the sex is high. The heat dissipation of the fuel tanks 21 and 31 is the material of the fuel tanks 21 and 31, the size of the fuel tanks 21 and 31 = the capacity of the fuel tanks 21 and 31, the shape of the fuel tanks 21 and 31 and the like. Can vary depending on the characteristics of. The heat dissipation of the fuel tanks 21 and 31 includes the positional relationship between the members arranged around the fuel tanks 21 and 31 and the fuel tanks 21 and 31, and the presence or absence of a heat radiation member that dissipates heat from the fuel tanks 21 and 31. It may also change depending on the surrounding environment of the fuel tanks 21 and 31. The second fuel tank 31 has lower heat dissipation than the first fuel tank 21. The capacity of the first fuel tank 21 and the capacity of the second fuel tank 31 may be the same or different.

The filling rate of the fuel tanks 21 and 31 is determined by the internal pressure and temperature of the fuel tanks 21 and 31. If the internal pressures of the two fuel tanks 21 and 31 are the same and the temperatures are the same, the filling rates of the two fuel tanks 21 and 31 are the same. Even if the internal pressures of the two fuel tanks 21 and 31 are the same, the filling rates of the two fuel tanks 21 and 31 are different when the temperatures are different. The higher the temperature of hydrogen gas, the lower the gas density. Therefore, if the internal pressures of the two fuel tanks 21 and 31 are the same, the fuel tanks 21 and 31 having the higher temperature will be the fuel tanks 21 and 31 having the lower temperature. The filling rate is lower than.

The supply flow path 41 includes a first supply path 42 connected to the first fuel tank 21, a second supply path 43 connected to the second fuel tank 31, and a first supply path 42 and a second supply path 43. A connection path 44 connected to the confluence is provided. The first supply path 42 and the second supply path 43 can be regarded as branching from the connection path 44 to the fuel tanks 21 and 31. The connection path 44 is connected to the fuel cell stack 11.

The filling flow path 52 includes a filling path 53 connected to the receptacle 51 and two branch paths 54 and 55 branching from the filling path 53. The first branch path 54, which is one of the branch paths 54 and 55, connects the filling path 53 and the first fuel tank 21. Of the branch paths 54 and 55, the second branch path 55, which is different from the first branch path 54, connects the filling path 53 and the second fuel tank 31.

The FCECU 61 is an electronic control unit that includes a CPU and a storage unit as hardware. Various programs for controlling the fuel cell system 10 are stored in the storage unit. The CPU executes various processes by referring to the storage unit. The CPU may be configured as one or more processors operating according to a computer program, one or more dedicated hardware circuits such as an ASIC, or a circuit including a combination thereof. The storage unit includes a memory such as a RAM and a ROM. The memory stores program code or instructions configured to cause the CPU to execute processing. Memory, or computer-readable medium, includes anything that can be accessed by a general purpose or dedicated computer.

The fuel gas supply device 20 includes a first main stop valve 22, a first pressure control valve 23, a first pressure sensor 24, a first temperature sensor 25, a second main stop valve 32, and a second pressure control valve. It includes 33, a second pressure sensor 34, a second temperature sensor 35, a third pressure sensor 45, and an injector 46.

The first main check valve 22 is opened and closed to switch between releasing and shutting off hydrogen gas from the first fuel tank 21. By switching the opening and closing of the first main check valve 22, it can be said that the supply and cutoff of hydrogen gas from the first fuel tank 21 to the fuel cell stack 11 can be switched. As the first main check valve 22, for example, a solenoid valve whose opening and closing is controlled by the FCECU 61 can be used. The first main check valve 22 is provided in the first supply path 42 or the first fuel tank 21.

The first pressure regulating valve 23 adjusts the pressure of the hydrogen gas released from the first fuel tank 21. The first pressure regulating valve 23 is a regulator that reduces the pressure of hydrogen gas released from the first fuel tank 21. The first pressure regulating valve 23 is provided in the first supply path 42. The first pressure regulating valve 23 is provided downstream of the first main stop valve 22 in the direction in which hydrogen gas flows.

The first pressure sensor 24 is provided between the first main stop valve 22 and the first pressure regulating valve 23 in the direction in which hydrogen gas flows. The first pressure sensor 24 measures the pressure between the first main stop valve 22 and the first pressure regulating valve 23. The pressure measured by the first pressure sensor 24 with the first main check valve 22 open can be regarded as the internal pressure P1 of the first fuel tank 21. The measured value of the first pressure sensor 24 is output to the FCECU 61. The first temperature sensor 25 measures the temperature T1 of the first fuel tank 21. The measured value of the first temperature sensor 25 is output to the FCECU 61. The temperature T1 of the first fuel tank 21 is the internal temperature of the first fuel tank 21.

The second main check valve 32 is opened and closed to switch between releasing and shutting off hydrogen gas from the second fuel tank 31. By switching the opening and closing of the second main check valve 32, it can be said that the supply and cutoff of hydrogen gas from the second fuel tank 31 to the fuel cell stack 11 can be switched. As the second main check valve 32, for example, a solenoid valve whose opening and closing is controlled by the FCECU 61 can be used. The second main check valve 32 is provided in the second supply path 43 or the second fuel tank 31.

The second pressure adjusting valve 33 adjusts the pressure of the hydrogen gas released from the second fuel tank 31. The second pressure regulating valve 33 is a regulator that reduces the pressure of the hydrogen gas released from the second fuel tank 31. The second pressure regulating valve 33 is provided in the second supply path 43. The second pressure regulating valve 33 is provided downstream of the second main stop valve 32 in the direction in which hydrogen gas flows.

The second pressure sensor 34 is provided between the second main stop valve 32 and the second pressure regulating valve 33 in the direction in which hydrogen gas flows. The second pressure sensor 34 measures the pressure between the second main stop valve 32 and the second pressure regulating valve 33. The pressure measured by the second pressure sensor 34 with the second main check valve 32 open can be regarded as the internal pressure P2 of the second fuel tank 31. The measured value of the second pressure sensor 34 is output to the FCECU 61. The second temperature sensor 35 measures the temperature T2 of the second fuel tank 31. The measured value of the second temperature sensor 35 is output to the FCECU 61. The temperature T2 of the second fuel tank 31 is the internal temperature of the second fuel tank 31.

The injector 46 is provided in the connecting path 44. When the injector 46 is opened, it injects hydrogen gas and supplies hydrogen gas to the fuel cell stack 11. As the injector 46, for example, an electromagnetically driven injector 46 is used.

The third pressure sensor 45 is provided in the connecting path 44. The third pressure sensor 45 is provided upstream of the injector 46 in the direction in which hydrogen gas flows. The third pressure sensor 45 measures the pressure P3 upstream of the injector 46 in the direction in which the hydrogen gas flows. The measured value of the third pressure sensor 45 is output to the FCECU 61.

The fuel gas supply device 20 includes a check valve 56. A check valve 56 is provided in each of the filling path 53, the first branch path 54, and the second branch path 55. The check valve 56 allows the flow of hydrogen gas from the receptacle 51 toward the fuel tanks 21 and 31, while restricting the flow of hydrogen gas from the fuel tanks 21 and 31 toward the receptacle 51. To do.

A vehicle ECU 71 is connected to the FCE ECU 61. The vehicle ECU 71 is an electronic control unit that controls the vehicle. The hardware configuration of the vehicle ECU 71 is, for example, the same as that of the FCE ECU 61. A start switch 72 for switching between a vehicle start state and a vehicle stop state is connected to the vehicle ECU 71. The vehicle ECU 71 switches between the started state and the stopped state of the vehicle by operating the start switch 72 by the passenger of the vehicle. The activated state is a state in which the vehicle can be driven and an in-vehicle electric power device such as an auxiliary machine can be driven by the operation of the passenger of the vehicle. The stopped state is a state in which the vehicle is not driven or the in-vehicle electric power device is not driven even if the vehicle is operated by the passenger of the vehicle. The FCECU 61 and the vehicle ECU 71 can communicate with each other by a communication protocol such as CAN: Controller Area Network or LIN: Local Interconnect Network.

Next, a filling device 81 for filling the fuel tanks 21 and 31 with hydrogen gas will be described. The filling device 81 includes a plug 82 connected to the receptacle 51, a control unit 83 for controlling the filling device 81, and a pressure sensor 84. The control unit 83 controls the supply and stop of the hydrogen gas from the plug 82. When the fuel tanks 21 and 31 are filled with hydrogen gas, the plug 82 is connected to the receptacle 51, and the hydrogen gas is supplied to the filling flow path 52 via the receptacle 51. The hydrogen gas supplied to the filling flow path 52 is filled in the first fuel tank 21 and the second fuel tank 31. The hydrogen gas supplied to the filling flow path 52 is filled in the fuel tanks 21 and 31 according to the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31. The pressure sensor 84 measures the supply pressure, which is the pressure of the hydrogen gas supplied from the filling device 81 to the fuel tanks 21 and 31.

When the plug 82 is connected to the vehicle, the control unit 83 starts filling the fuel tanks 21 and 31 with hydrogen gas. When the pressure measured by the pressure sensor 84 reaches a predetermined set pressure, the control unit 83 ends the filling of hydrogen gas. In the present embodiment, the full filling of the fuel tanks 21 and 31 means that the measured value of the pressure sensor 84 becomes the set pressure.

Next, the control performed by the FCECU 61 will be described.
When the state of the vehicle is switched from the stopped state to the started state by the operation of the start switch 72 by the passenger of the vehicle, the vehicle ECU 71 gives a power generation request command to the FCE ECU 61. Upon receiving the power generation request command, the FCECU 61 controls the air supply system 12 so that air is supplied to the fuel cell stack 11. The FCECU 61 controls the fuel gas supply device 20 so that hydrogen gas is supplied to the fuel cell stack 11. Hereinafter, the control of the fuel gas supply device 20 performed by the FCECU 61 when the vehicle is in the activated state will be described.

As shown in FIG. 2, the FCECU 61 performs the processes of steps S1 to S4 when it receives the power generation request command. When the FCECU 61 finishes the processing of steps S1 to S4, the FCECU 61 repeats the processing of steps S2 to S4 from the next control cycle. That is, the process of step S1 is performed only once when the power generation request command is received, and the process excluding the process of step S1 is repeatedly performed in the subsequent control cycle.

The FCECU 61 opens the first main check valve 22 and the second main check valve 32 in step S1. The first main check valve 22 and the second main check valve 32 are closed when the vehicle is stopped.

Next, in step S2, the FCECU 61 determines whether or not the measured value of the first pressure sensor 24 is lower than the measured value of the second pressure sensor 34 by a predetermined value or more. That is, the FCECU 61 determines whether or not the internal pressure P1 of the first fuel tank 21 is lower than the internal pressure P2 of the second fuel tank 31 by a predetermined value or more. If the determination result in step S2 is affirmative, the FCECU 61 performs the process in step S3. If the determination result in step S2 is negative, the FCECU 61 performs the process in step S4. The measured value of the first pressure sensor 24 and the measured value of the second pressure sensor 34 measured in step S2 are stored in the RAM of the FCECU 61.

The FCECU 61 opens the second main check valve 32 in step S3. If the second main check valve 32 is already open at the time of processing in step S3, the FCECU 61 maintains the state in which the second main check valve 32 is open. As a result, hydrogen gas is released from both the first fuel tank 21 and the second fuel tank 31.

The FCECU 61 closes the second main check valve 32 in step S4. If the second main check valve 32 is already closed at the time of processing in step S4, the FCECU 61 maintains this state. As a result, hydrogen gas is released from the first fuel tank 21. It can be said that the opening / closing of the second main check valve 32 is switched depending on the determination result in step S2. The FCECU 61 controls the internal pressure P1 of the first fuel tank 21 to be lower than the internal pressure P2 of the second fuel tank 31 by a predetermined value or more at the time of power generation of the fuel cell stack 11. By executing the processes of steps S2 to S4, the FCECU 61 functions as a pressure control unit. When the second main check valve 32 is closed in step S4, the internal pressure P2 of the second fuel tank 31 cannot be measured by the second pressure sensor 34 until the determination result in step S2 becomes affirmative in the subsequent control cycle. .. When the second main check valve 32 is closed, the internal pressure P2 of the second fuel tank 31 does not change. Therefore, in the determination in step S2, the second pressure before the second main stop valve 32 is closed in step S4. The determination may be made using the measured value of the sensor 34. That is, the determination may be made using the measured value of the second pressure sensor 34 stored in the RAM of the FCECU 61.

By controlling the injector 46, the FCECU 61 supplies hydrogen gas supplied to the connection path 44 from both the first fuel tank 21 and the second fuel tank 31 or only the first fuel tank 21 to the fuel cell stack 11. To do.

When the processes of steps S2 to S4 are repeated, the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 follows a predetermined value. The predetermined value of this embodiment is a predetermined fixed value.

Hereinafter, the predetermined value will be described in detail.
FIG. 3 shows the relationship between the operating time of the vehicle when the fuel gas supply device 20 of the present embodiment is used and the internal pressures of the fuel tanks 21 and 31. The operating time of the vehicle can also be regarded as the power generation time of the fuel cell stack 11.

As shown in FIG. 3, when the vehicle starts operation at time T0, hydrogen gas is supplied only from the first fuel tank 21. At time T10, the internal pressure P1 of the first fuel tank 21 becomes lower than the internal pressure P2 of the second fuel tank 31 by a predetermined value or more, and hydrogen gas is supplied from both the first fuel tank 21 and the second fuel tank 31. Will be. After time T10, the supply of hydrogen gas from the first fuel tank 21 and the supply of hydrogen gas from both the first fuel tank 21 and the second fuel tank 31 are the internal pressures P1 and the second of the first fuel tank 21. The switching is performed depending on whether or not the difference between the fuel tank 31 and the internal pressure P2 becomes a predetermined value or more. As a result, the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 is maintained substantially constant.

It is assumed that the fuel tanks 21 and 31 are filled with hydrogen gas at time T20, which is the time when the internal pressure P1 of the first fuel tank 21 becomes the internal pressure P11, and hydrogen is filled in the fuel tanks 21 and 31 until the specified internal pressure is reached. Suppose it is filled with gas. The specified internal pressure is, for example, the internal pressure when the fuel tanks 21 and 31 are fully filled. Assuming that the difference between the specified internal pressure and the internal pressures P1 and P2 of the fuel tanks 21 and 31 at time T20 is the differential pressure, the differential pressure ΔP1 of the first fuel tank 21 is larger than the differential pressure ΔP2 of the second fuel tank 31. large. The difference between the differential pressure ΔP1 and the differential pressure ΔP2 is the same as the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31, and can be regarded as a predetermined value.

FIG. 4 shows the relationship between the filling differential pressure and the temperatures T1 and T2 of the fuel tanks 21 and 31. The filling differential pressure is the difference between the internal pressures P1 and P2 of the fuel tanks 21 and 31 before filling and the internal pressures P1 and P2 of the fuel tanks 21 and 31 after filling when the fuel tanks 21 and 31 are filled with hydrogen gas. Is. That is, it is the internal pressure increased by filling with hydrogen gas. As can be seen from FIG. 4, the temperature of the second fuel tank 31, which has lower heat dissipation than that of the first fuel tank 21, tends to rise when filled with hydrogen gas, as compared with the first fuel tank 21. Further, the temperature of each of the fuel tanks 21 and 31 rises as the filling differential pressure increases.

The temperature T1 of the first fuel tank 21 when the first fuel tank 21 is filled with hydrogen gas having a differential pressure ΔP1 and the second fuel tank when the second fuel tank 31 is filled with hydrogen gas having a differential pressure ΔP2. It is the same as the temperature T2 of 31. The predetermined value of the present embodiment is the temperature T1 of the first fuel tank 21 when the internal pressure P1 of the first fuel tank 21 starts filling with hydrogen gas from the state of the internal pressure P11 and is filled with hydrogen gas until the specified internal pressure is reached. And the temperature T2 of the second fuel tank 31 can be said to be the same value. If the internal pressure P11 is the internal pressure P1 of the first fuel tank 21 when the filling rate of the first fuel tank 21 is 20%, hydrogen gas is filled from the state where the filling rate of the first fuel tank 21 is 20%. When started, it can be said that the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 become the same when the internal pressures P1 and P2 of the fuel tanks 21 and 31 reach the specified internal pressure. The internal pressure P11 is a value arbitrarily determined depending on the usage environment of the vehicle and the type of the vehicle, and is, for example, a pressure at which the fuel tanks 21 and 31 are easily filled with hydrogen gas. In a vehicle that is predicted to be easily filled when the filling rate of the fuel tanks 21 and 31 is 20% to 50%, a predetermined value can be obtained from the internal pressure P11 when the filling rate is 20% to 50%. Good.

The difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 when the hydrogen gas is filled can change depending on the magnitude of the predetermined value. If the predetermined value is made excessively small, the difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 when the hydrogen gas is filled may not be sufficiently reduced. The predetermined value is filled with hydrogen gas in consideration of the internal pressure P1 of the first fuel tank 21 and the heat dissipation of the fuel tanks 21 and 31 at the filling rate predicted to be filled with hydrogen gas. When this is done, the difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 is set to be small.

Even when hydrogen gas filling is started from a state where the internal pressure P1 of the first fuel tank 21 is equal to or higher than the internal pressure P11 or lower than the internal pressure P11, the internal pressures P1 and P2 of the two fuel tanks 21 and 31 are the same. The difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 can be reduced as compared with the case where the filling of hydrogen gas is started from. Further, even if the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 is less than a predetermined value, the internal pressure P1 of the first fuel tank 21 is larger than the internal pressure P2 of the second fuel tank 31. If it is low, the difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 when the hydrogen gas is filled can be reduced. That is, even when the hydrogen gas filling is completed before the time T10 shown in FIG. 3 or after the time T20, the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 at the end of the filling are completed. The difference can be reduced.

The FCECU 61 controls the internal pressure P1 of the first fuel tank 21 to be lower than the internal pressure P2 of the second fuel tank 31 during power generation of the fuel cell stack 11. However, as shown in FIG. 3, at the start of power generation of the fuel cell stack 11, the internal pressure P1 of the first fuel tank 21 may exceed the internal pressure P2 of the second fuel tank 31.

The operation of this embodiment will be described.
In FIG. 5, as a comparative example, the first fuel tank 21 and the first fuel tank 21 and the first when hydrogen gas is supplied to the filling flow path 52 from the state where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are the same. 2 Changes in the internal pressures P1 and P2 of the fuel tank 31 are shown. Further, in FIG. 6, as a comparative example, the first fuel tank 21 is a case where hydrogen gas is supplied to the filling flow path 52 from the same state where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are the same. And the changes in the temperatures T1 and T2 of the second fuel tank 31 are shown.

As shown in FIG. 5, when hydrogen gas is supplied to the filling flow path 52 from the same state where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are the same, the internal pressure P1 of the first fuel tank 21 And the internal pressure P2 of the second fuel tank 31 rises in the same manner.

As shown in FIG. 6, when the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 rise in the same manner, the heat dissipation of the first fuel tank 21 and the heat dissipation of the second fuel tank 31 become Due to the difference between the two, the difference between the temperature T1 of the first fuel tank 21 and the temperature T2 of the second fuel tank 31 becomes large with the passage of time. It can be said that the gas density of the second fuel tank 31 becomes lower than the gas density of the first fuel tank 21 due to the thermal expansion of the hydrogen gas. When the filling of hydrogen gas is completed, the temperature difference between the two fuel tanks 21 and 31 becomes smaller. As the temperature difference becomes smaller, the internal pressures P1 and P2 of the two fuel tanks 21 and 31 decrease. At this time, the internal pressure of the second fuel tank 31, whose temperature is significantly lowered, is significantly lower than that of the first fuel tank 21. That is, even if the internal pressures P1 and P2 of the two fuel tanks 21 and 31 are the same at the end of filling, the filling rate of the second fuel tank 31 is the second due to the difference in heat dissipation between the two fuel tanks 21 and 31. 1 It is lower than the filling rate of the fuel tank 21.

As shown in FIG. 7, in the fuel gas supply device 20 of the present embodiment, the internal pressure P1 of the first fuel tank 21 is lower than the internal pressure P2 of the second fuel tank 31 at the time when the filling of hydrogen gas is started. The hydrogen gas supplied from the filling device 81 to the filling path 53 is filled in the first fuel tank 21 and the second fuel tank 31 according to the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31. .. Since the internal pressure P1 of the first fuel tank 21 is lower than the internal pressure P2 of the second fuel tank 31, when hydrogen gas is supplied to the filling path 53, the hydrogen gas is likely to be supplied to the first fuel tank 21. With the passage of time, the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 become the same. When filled with hydrogen gas, the internal pressure P1 of the first fuel tank 21 rises more than that of the second fuel tank 31.

FIG. 8 shows the relationship between the time and the temperature when the internal pressures P1 and P2 of the fuel tanks 21 and 31 change as shown in FIG. The greater the rise in the internal pressures P1 and P2 of the fuel tanks 21 and 31, the greater the rise in the temperature of the fuel tanks 21 and 31. Therefore, the temperature T1 of the first fuel tank 21 rises significantly as compared with the case where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 start filling with hydrogen gas from the same state. On the other hand, since the first fuel tank 21 has higher heat dissipation than the second fuel tank 31, when the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 become the same, the second fuel tank 31 becomes available. The temperature will rise more slowly than that. As a result, the temperatures T1 and the first of the first fuel tank 21 at the end of filling are compared with the case where the filling of hydrogen gas is started from the same state of the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31. 2 The difference in temperature T2 of the fuel tank 31 becomes small. That is, even if the filling of hydrogen gas is completed and the temperatures of the two fuel tanks 21 and 31 decrease, the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 is small. Therefore, even if the filling of the hydrogen gas is completed when the first fuel tank 21 reaches the specified internal pressure, the filling rate of the second fuel tank 31 becomes high.

It is also conceivable to provide a flow rate control mechanism in the first branch path 54 to limit the flow rate of hydrogen gas to the first fuel tank 21 when the filling device 81 fills the hydrogen gas. In this case, the filling rate of the first fuel tank 21 and the filling rate of the second fuel tank are limited by limiting the rise of the internal pressure P1 of the first fuel tank 21 to the rise of the internal pressure P2 of the second fuel tank 31 when the hydrogen gas is filled. The difference from the filling rate of 31 can be reduced. As a result, even when the filling rate of hydrogen gas is started from the same state of the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31, the filling rate of the second fuel tank 31 is improved. It is possible.

However, when the flow rate control mechanism is provided in the first branch passage 54, the amount of hydrogen gas filled in the first fuel tank 21 is adjusted by controlling the flow rate control mechanism during filling of the hydrogen gas by the filling device 81. There is a need to. When the filling device 81 fills the hydrogen gas, the vehicle is stopped. When the vehicle is stopped, the FCECU 61 is in sleep mode. The sleep mode is a state in which some or all functions are restricted. Therefore, in order to control the flow rate control mechanism, it is necessary to wake up the FCECU 61, which causes an increase in power consumption. Further, by providing the flow rate control mechanism, the number of parts is increased.

Further, even when the filling of hydrogen gas is started from the state where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are the same, hydrogen is hydrogen until the second fuel tank 31 is fully filled. By filling the gas, the filling rate of the second fuel tank 31 can be improved. However, if the second fuel tank 31 is filled with hydrogen gas until it is fully filled, the first fuel tank 21 will be overfilled with hydrogen gas.

On the other hand, in the present embodiment, the FCECU 61 controls the first main stop valve 22 and the second main stop valve 32 during the power generation of the fuel cell stack 11, and the internal pressure P1 of the first fuel tank 21 is set to the second fuel tank 31. By making the internal pressure lower than P2, the filling rate of the second fuel tank 31 can be improved when filling hydrogen gas. Therefore, it is not necessary to control the flow rate control mechanism by the FCECU 61 during the filling of hydrogen gas by the filling device 81. Further, in the present embodiment, the filling rate of the second fuel tank 31 is improved by reducing the difference between the filling rate of the first fuel tank 21 and the filling rate of the second fuel tank 31, so that the second fuel Even if the filling rate of the tank 31 is improved, the first fuel tank 21 is unlikely to be overfilled.

The effect of this embodiment will be described.
(1) By lowering the internal pressure P1 of the first fuel tank 21 to be lower than the internal pressure P2 of the second fuel tank 31 during power generation of the fuel cell stack 11, the temperature T1 of the first fuel tank 21 is filled with hydrogen gas. The difference between the temperature T2 and the temperature T2 of the second fuel tank 31 can be reduced. Therefore, the difference in filling rate between the first fuel tank 21 and the second fuel tank 31 due to the thermal expansion of hydrogen gas can be reduced. Compared with the case where the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are filled with hydrogen gas from the same state, the filling rate of the second fuel tank 31 can be improved. More specifically, when the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 are filled with hydrogen gas from the same state, the hydrogen gas is filled when the first fuel tank 21 is fully filled. When the filling rate of the first fuel tank 21 is completed, the filling rate of the second fuel tank 31 becomes lower than the filling rate of the first fuel tank 21 by the difference between the filling rate of the first fuel tank 21 and the filling rate of the second fuel tank 31. On the other hand, by reducing the difference between the filling rate of the first fuel tank 21 and the filling rate of the second fuel tank 31, the filling rate of the first fuel tank 21 and the filling rate of the second fuel tank 31 can be reduced. Insufficient filling of the second fuel tank 31 due to the difference can be suppressed.

(2) The FCECU 61 controls so that the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 becomes a predetermined value or more. By setting a predetermined value, the difference between the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 can be adjusted.

The embodiment can be modified and implemented as follows. The embodiments and the following modifications can be implemented in combination with each other to the extent that they are technically consistent.
○ The FCECU 61 supplies hydrogen gas to the fuel cell stack 11 only from the first fuel tank 21 until the measured value of the first pressure sensor 24, that is, the internal pressure P1 of the first fuel tank 21 reaches a predetermined threshold value. The first main stop valve 22 and the second main stop valve 32 may be controlled as such. The threshold value is, for example, a value set so that it can be detected that the hydrogen gas in the first fuel tank 21 is exhausted. For example, the threshold value is set to a value obtained by adding a margin to the internal pressure P1 when the hydrogen gas in the first fuel tank 21 is exhausted. The FCECU 61 closes the second main check valve 32 until the measured value of the first pressure sensor 24 reaches the threshold value. When the measured value of the first pressure sensor 24 reaches the threshold value, the FCECU 61 opens the second main stop valve 32 and controls so that hydrogen gas is supplied from the second fuel tank 31 to the fuel cell stack 11. It can be said that the FCECU 61 preferentially uses the hydrogen gas of the first fuel tank 21, and when the hydrogen gas of the first fuel tank 21 is exhausted or is exhausted, the hydrogen gas of the second fuel tank 31 is used. Since hydrogen gas only needs to be supplied from the first fuel tank 21 until the measured value of the first pressure sensor 24 reaches a predetermined threshold value, the control performed by the FCECU 61 can be simplified.

○ The fuel gas supply device 20 may include three or more fuel tanks. In this case, the relationship between the first fuel tank and the second fuel tank may be established for all combinations of two fuel tanks out of the three or more fuel tanks. For example, the fuel gas supply device 20 is provided with three fuel tanks, the fuel tank having the highest heat dissipation is the high heat dissipation fuel tank, the fuel tank having the second highest heat dissipation is the medium heat dissipation fuel tank, and the fuel tank has the lowest heat dissipation. It is assumed that the fuel tank is a low heat dissipation fuel tank. In this case, in the combination of the high heat dissipation fuel tank and the medium heat dissipation fuel tank, the high heat dissipation fuel tank becomes the first fuel tank and the medium heat dissipation fuel tank becomes the second fuel tank. The FCECU 61 controls the internal pressure of the high heat dissipation fuel tank to be lower than the internal pressure of the medium heat dissipation fuel tank during power generation of the fuel cell stack 11. In the combination of the medium heat dissipation fuel tank and the low heat dissipation fuel tank, the medium heat dissipation fuel tank becomes the first fuel tank and the low heat dissipation fuel tank becomes the second fuel tank. The FCECU 61 controls the internal pressure of the medium heat dissipation fuel tank to be lower than the internal pressure of the low heat dissipation fuel tank during power generation of the fuel cell stack 11. Similarly, in the combination of the high heat dissipation fuel tank and the low heat dissipation fuel tank, the high heat dissipation fuel tank becomes the first fuel tank and the low heat dissipation fuel tank becomes the second fuel tank. That is, the first fuel tank and the second fuel tank indicate any two fuel tanks among the plurality of fuel tanks, and do not indicate that there are two fuel tanks. When the fuel gas supply device 20 includes three or more fuel tanks, it can be said that during power generation of the fuel cell stack 11, control is performed so that the internal pressure of the fuel tanks decreases in descending order of heat dissipation.

○ The predetermined value may be a variable value that changes according to the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31. The lower the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31, the larger the temperature that rises when hydrogen gas is filled until it is fully filled. Therefore, as the internal pressure P1 of the first fuel tank 21 and the internal pressure P2 of the second fuel tank 31 become lower, the predetermined values are increased to increase the temperature T1 and the temperature T1 of the first fuel tank 21 when the hydrogen gas is filled. 2 The difference in temperature T2 of the fuel tank 31 can be reduced.

○ The fuel cell stack 11 may be mounted on a mobile device or used as a stationary power source.

11 ... Fuel cell stack, 20 ... Fuel gas supply device, 21 ... 1st fuel tank, 22 ... 1st main check valve, 31 ... 2nd fuel tank, 32 ... 2nd main stop valve, 53 ... Filling path, 54, 55 ... branch path, 61 ... FCECU functioning as a pressure control unit, 81 ... filling device.

Claims (3)

A fuel gas supply device that supplies fuel gas to the fuel cell stack.
The first fuel tank in which the fuel gas is stored and
A second fuel tank in which the fuel gas is stored and has lower heat dissipation than the first fuel tank,
A first main check valve for switching between supply and interruption of the fuel gas from the first fuel tank to the fuel cell stack,
A second main check valve that switches between supplying and shutting off the supply of the fuel gas from the second fuel tank to the fuel cell stack.
A filling path through which the fuel gas supplied from the filling device for filling the first fuel tank and the second fuel tank with the fuel gas flows.
A branch path that branches from the filling path to the first fuel tank and the second fuel tank, and
A pressure control unit that controls the first main stop valve and the second main stop valve so that the internal pressure of the first fuel tank becomes lower than the internal pressure of the second fuel tank during power generation of the fuel cell stack. A fuel gas supply device equipped with. The pressure control unit controls the first main stop valve and the second main stop valve so that the internal pressure of the first fuel tank becomes lower than the internal pressure of the second fuel tank by a predetermined value or more. The fuel gas supply device described in. The pressure control unit is the first main stop valve so that the fuel gas is supplied to the fuel cell stack only from the first fuel tank until the internal pressure of the first fuel tank reaches a predetermined threshold value. And the first main stop valve is controlled so that the fuel gas is supplied from the second fuel tank to the fuel cell stack when the internal pressure of the first fuel tank reaches the threshold value. The fuel gas supply device according to claim 1, wherein the second main stop valve is controlled.