Fuel cell vehicles

Abstract

To provide a fuel cell vehicle that can transition to a drivable state regardless of the surrounding environment. [Solution] A fuel cell vehicle capable of performing a warm-up operation of the fuel cell by generating electricity from the fuel cell, comprising: a battery for driving; a charging unit that supplies electricity generated by the fuel cell during the warm-up operation to the battery and charges the battery; a detection unit that detects the amount of charge stored in the battery; and a charging continuation unit that, when the conditions for ending the warm-up operation are met, if the amount of charge detected by the detection unit is less than a first amount of charge, continues to charge the battery using the warm-up operation.

Description

Technical Field

[0001] The present invention relates to a fuel cell vehicle.

Background Art

[0002] Patent Document 1 discloses a fuel cell vehicle. Such a fuel cell vehicle can perform a warm-up operation of the fuel cell. During the warm-up operation of the fuel cell, the temperature of the fuel cell is increased by utilizing the self-heat generated by the power generation of the fuel cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to prevent the moisture in the fuel cell from freezing during the stop of the operation of the fuel cell vehicle due to key-off or the like, the warm-up operation of the fuel cell is executed during the stop of the operation.

[0005] By the way, a fuel cell vehicle includes a battery for running. In the battery for running, the electric power generated by the power generation of the fuel cell is stored, and the electric power is mainly used for the running of the vehicle.

[0006] The discharge capacity of such a battery changes depending on the environment around the fuel cell vehicle. For example, the discharge capacity of the battery in a low-temperature environment is lower than the discharge capacity of the battery in a normal-temperature environment. If the discharge capacity of the battery is insufficient during the stop of the operation of the fuel cell vehicle, there is a possibility that the next start of the fuel cell vehicle becomes difficult.

[0007] Therefore, for a fuel cell vehicle, it is desirable to sufficiently secure the power storage amount of the battery while considering the influence accompanying the change in the discharge capacity of the battery.

[0008] This invention was made in view of the above circumstances, and aims to provide a fuel cell vehicle that can transition to a drivable state regardless of the surrounding environment. [Means for solving the problem]

[0009] The present invention has been made to solve at least some of the aforementioned problems and can be realized in the following embodiments or application examples.

[0010] (1) The fuel cell vehicle relating to this application example is a fuel cell vehicle capable of performing a warm-up operation of the fuel cell by generating electricity from the fuel cell, and comprises a battery for driving, a charging unit that supplies electricity generated by the fuel cell during the warm-up operation to the battery and charges the battery, a detection unit that detects the amount of charge stored in the battery, and a charging continuation unit that, when the conditions for ending the warm-up operation are met, if the amount of charge detected by the detection unit is less than a first amount of charge, continues to charge the battery using the warm-up operation.

[0011] In the fuel cell vehicle according to this application example, even if the conditions for ending the fuel cell warm-up are met, if the amount of stored energy detected by the detection unit is less than the first stored energy level, battery charging using the fuel cell warm-up will continue. In other words, in the fuel cell vehicle according to this application example, the battery's stored energy level can be kept high by utilizing the fuel cell warm-up. Furthermore, this allows the fuel cell vehicle to transition to a drivable state regardless of the surrounding environment.

[0012] (2) In a fuel cell vehicle according to the application example of (1) above, the charging continuation unit may terminate the charging of the battery using the warm-up operation when the conditions for terminating the warm-up operation are met and the amount detected by the detection unit becomes equal to or greater than the second stored amount. This makes it possible to maintain the amount of stored energy in the high-voltage battery at or above the second stored amount while suppressing excessive consumption of fuel gas required for power generation by the fuel cell.

[0013] (3) The fuel cell vehicle according to the application example of (1) above is equipped with a temperature detection unit that detects the temperature of the fuel cell, and the start condition for the warm-up operation may be that the temperature detected by the temperature detection unit falls below a first temperature. This makes it possible to maintain a high battery charge even in so-called low-temperature environments where the temperature of the fuel cell falls below the first temperature. In other words, the fuel cell vehicle can transition to a drivable state even when the surrounding environment is a low-temperature environment.

[0014] (4) In the fuel cell vehicle according to the application example of (1) above, the condition for ending the warm-up operation may be that the temperature detected by the temperature detection unit is 2 or higher. This makes it possible to remove the water generated during power generation using the residual heat of the fuel cell itself after the warm-up operation of the fuel cell is completed. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing an example of the mechanical configuration of the vehicle according to this embodiment. [Figure 2] This block diagram shows an example of the electrical configuration of the vehicle according to this embodiment. [Figure 3] This is a flowchart illustrating an example of the operation of the vehicle according to this embodiment. [Modes for carrying out the invention]

[0016] 1. This embodiment Figure 1 is a schematic diagram showing an example of the mechanical configuration of vehicle 1 in this embodiment. In Figure 1, the gas system and the like in vehicle 1 are shown with dashed lines, and the electrical system is shown with solid lines.

[0017] Vehicle 1 is a fuel cell vehicle (FCV). Vehicle 1 is equipped with a driving system 10. The driving system 10 is a system for driving vehicle 1. The driving system 10 is started, for example, by turning the key on. The operation of the driving system 10 is stopped, for example, by turning the key off.

[0018] The running system 10 includes a fuel cell system 12. The fuel cell system 12 is a system that reacts hydrogen with oxygen to generate electricity. The fuel cell system 12 includes a fuel cell 14, an air supply passage 16, an air compressor 18, a hydrogen tank 20, a hydrogen supply passage 22, a regulating valve 24, an air discharge passage 26, a hydrogen discharge passage 28, a discharge valve 30, a hydrogen circulation passage 32, a pump 34, etc.

[0019] <​​​​​​​​​​​​​​​​​​​​Furthermore, in the fuel cell 14, water is produced by a chemical reaction between oxygen in the air and hydrogen gas. In addition, since the chemical reaction between oxygen in the air and hydrogen gas is an exothermic reaction, the fuel cell 14 generates its own heat when generating electricity.

[0025] The oxygen in the air supplied to the fuel cell 14 decreases due to a chemical reaction with hydrogen gas. On the other hand, the amount of moisture in the air increases as water is produced by a chemical reaction between the oxygen in the air and hydrogen gas. The air with increased moisture content is discharged into the atmosphere through the air discharge passage 26. This air with increased moisture content can also be described as the air that has passed through the fuel cell 14.

[0026] The air discharge passage 26 forms an air discharge channel. One end of the air supply passage 16 is connected to the cathode side of the fuel cell 14.

[0027] A portion of the hydrogen gas supplied to the fuel cell 14 is consumed by reacting with oxygen in the air. On the other hand, the remaining hydrogen gas supplied to the fuel cell 14 is discharged into the hydrogen discharge channel 28. The remaining hydrogen gas supplied to the fuel cell 14 can be described as hydrogen gas that was not consumed by reacting with oxygen in the air, or as hydrogen gas that passed through the fuel cell 14.

[0028] The hydrogen discharge channel 28 forms a hydrogen gas discharge channel. One end of the hydrogen discharge channel 28 is connected to the anode side of the fuel cell 14.

[0029] The discharge valve 30 is an electrically controllable solenoid valve and is installed in the hydrogen discharge passage 28. When the discharge valve 30 is open, the hydrogen gas that has passed through the fuel cell 14 is discharged into the atmosphere via the hydrogen discharge passage 28.

[0030] The area downstream of the control valve 24 in the hydrogen supply passage 22 and the area upstream of the discharge valve 30 in the hydrogen discharge passage 28 are connected by a hydrogen circulation passage 32. The hydrogen circulation passage 32 forms a circulation path for hydrogen gas.

[0031] Pump 34 is an electrically controllable pump located in the hydrogen circulation path 32. When pump 34 is operating, the hydrogen gas that has passed through the fuel cell 14 is returned to the hydrogen supply path 22.

[0032] The driving system 10 also includes an inverter 36, a motor 38, a first DC / DC converter 40, a high-voltage battery 42, a second DC / DC converter 44, and a low-voltage battery 46, among other components.

[0033] The inverter 36 is electrically connected to the fuel cell 14, and the motor 38 is electrically connected to the inverter 36. Furthermore, a first DC / DC converter 40 is electrically connected between the fuel cell 14 and the inverter 36, and a high-voltage battery 42 is electrically connected to the first DC / DC converter 40. Specifically, the connection between the fuel cell 14 and the inverter 36 refers to the electrical circuit connecting the fuel cell 14 and the inverter 36.

[0034] The high-voltage battery 42 is a large-capacity secondary battery. The high-voltage battery 42 is, for example, a lithium-ion battery with a maximum voltage set to approximately 200V. The power stored in the high-voltage battery 42 is mainly used for driving the vehicle 1, that is, for driving the motor 38. The power stored in the high-voltage battery 42 is also used for charging the low-voltage battery 46, etc.

[0035] The first DC / DC converter 40 controls the charging power to the high-voltage battery 42 and the output power of the high-voltage battery 42. Specifically, the first DC / DC converter 40 controls the charging power from the fuel cell 14 to the high-voltage battery 42. The first DC / DC converter 40 also controls the output power from the high-voltage battery 42 to the inverter 36.

[0036] The inverter 36 converts either the DC power output from the fuel cell 14 or the DC power output from the high-voltage battery 42 via the first DC / DC converter 40 into three-phase AC power and supplies it to the motor 38.

[0037] The second DC / DC converter 44 is electrically connected to the high-voltage battery 42, and the second DC / DC converter 44 is electrically connected to the low-voltage battery 46.

[0038] The low-voltage battery 46 is a secondary battery whose maximum voltage is set lower than that of the high-voltage battery 42. The low-voltage battery 46 is, for example, a lead-acid battery whose maximum voltage is set to about 12V. The power stored in the low-voltage battery 46 is used to supply power to auxiliary devices such as sensors, and to the control unit 54, memory unit 56, etc., which will be described later, when the driving system 10 is stopped, that is, when power generation is not taking place.

[0039] The second DC / DC converter 44 controls the charging power to the low-voltage battery 46. Specifically, the second DC / DC converter 44 controls the charging power from the high-voltage battery 42 to the low-voltage battery 46.

[0040] Figure 2 is a block diagram showing an example of the electrical configuration of vehicle 1 in this embodiment. In addition to the driving system 10, vehicle 1 includes a first temperature sensor 48, a second temperature sensor 50, a battery monitor 52, a control unit 54, and a storage unit 56.

[0041] Furthermore, the control unit 54 is electrically connected to each of the following via control system circuits such as a bus: the air compressor 18, the control valve 24, the discharge valve 30, the pump 34, the inverter 36, the first DC / DC converter 40, the second DC / DC converter 44, the first temperature sensor 48, the second temperature sensor 50, the battery monitor 52, and the memory unit 56.

[0042] The first temperature sensor 48 is installed on the fuel cell 14 and detects the temperature of the fuel cell 14. The second temperature sensor 50 is installed on the vehicle body (not shown) of the vehicle 1 and detects the temperature of the atmosphere (air temperature).

[0043] The battery monitor 52 is installed on the high-voltage battery 42 and detects the charge state of the high-voltage battery 42. Specifically, the battery monitor 52 detects the State of Charge (SOC) of the high-voltage battery 42. In other words, the battery monitor 52 detects the amount of charge stored in the high-voltage battery 42.

[0044] The control unit 54 is a control unit such as an ECU (Electronic Control Unit). The control unit 54 includes a processor such as a CPU (Central Processing Unit). The storage unit 56 is, for example, an HDD (Hard Disk Drive), ROM (Read Only Memory), RAM (Random Access Memory), SSD (Solid State Drive), or any combination thereof.

[0045] The memory unit 56 stores programs and data for realizing various functions of the vehicle 1. The memory unit 56 also stores information input from the first temperature sensor 48, the second temperature sensor 50, and the battery monitor 52 in data format.

[0046] Furthermore, the control unit 54 functions as a warm-up unit 58, a charging unit 60, a charging continuation unit 62, etc., by executing a program stored in the memory unit 56.

[0047] The warm-up unit 58 performs a warm-up operation of the fuel cell 14. Specifically, when the start condition is met, the warm-up unit 58 starts the fuel cell system 12 to begin the warm-up operation of the fuel cell 14. On the other hand, when the end condition is met, the warm-up unit 58 stops the operation of the fuel cell system 12 to end the warm-up operation of the fuel cell 14. In other words, once the start condition is met, the warm-up unit 58 continues to perform the warm-up operation of the fuel cell 14 until the end condition is met.

[0048] The warm-up operation of the fuel cell 14 is a process in which the fuel cell 14 generates electricity, causing it to self-heat and raise its temperature.

[0049] The conditions for starting the warm-up operation of the fuel cell 14 are met when the temperature detected by the first temperature sensor 48 while the driving system 10 is stopped, that is, when the temperature of the fuel cell 14 falls below the first temperature.

[0050] Furthermore, the start condition for warming up the fuel cell 14 may be met when the temperature detected by the second temperature sensor 50 while the driving system 10 is stopped, that is, when the ambient temperature falls below the first temperature. The first temperature should be set to a temperature below 0 degrees Celsius, the temperature at which water freezes, for example, a temperature of about minus 20 degrees Celsius.

[0051] The condition for ending the warm-up operation of the fuel cell 14 is met when the temperature detected by the first temperature sensor 48, i.e., the temperature of the fuel cell 14, reaches or exceeds the second temperature while the driving system 10 is stopped.

[0052] The second temperature is higher than the first temperature. Furthermore, the second temperature is also the temperature at which the waste heat from the fuel cell 14 can be used to remove the water generated during power generation after the warm-up period of the fuel cell 14 is complete. The second temperature should be set to 100 degrees Celsius or higher; for example, it can be set to around 200 degrees Celsius.

[0053] The charging unit 60 controls the first DC / DC converter 40 and charges the high-voltage battery 42 by supplying the power generated by the fuel cell 14 to the high-voltage battery 42. Specifically, the charging unit 60 charges the high-voltage battery 42 by supplying the power generated by the fuel cell 14 during the warm-up operation of the fuel cell 14 to the high-voltage battery 42.

[0054] The charging unit 60 starts charging the high-voltage battery 42 when the conditions for starting the warm-up operation of the fuel cell 14 are met. On the other hand, the charging unit 60 stops charging the high-voltage battery 42 when the conditions for ending the warm-up operation of the fuel cell 14 are met. In other words, the charging unit 60 continues to charge the high-voltage battery 42 from the time the conditions for starting the warm-up operation of the fuel cell 14 are met until the conditions for ending the warm-up operation are met.

[0055] When the conditions for ending the warm-up operation of the fuel cell 14 are met, if the amount of charge stored in the high-voltage battery 42 is less than the first amount, the charging continuation unit 62, in cooperation with the warm-up operation unit 58 and the charging unit 60, will continue (extend) both the warm-up operation of the fuel cell 14 and the charging of the high-voltage battery 42.

[0056] In other words, when the conditions for ending the warm-up operation of the fuel cell 14 are met, the charging continuation unit 62 refers to the detection result from the battery monitor 52, and if the amount of charge stored in the high-voltage battery 42 is less than the first amount of charge, it continues to charge the high-voltage battery 42 using the warm-up operation of the fuel cell 14. The first amount of charge is, for example, an amount of charge equivalent to 60 percent of the State of Charge (SOC).

[0057] Furthermore, when the conditions for ending the warm-up operation of the fuel cell 14 are met and the amount of charge stored in the high-voltage battery 42 reaches the second amount or more, the charging continuation unit 62 terminates both the warm-up operation of the fuel cell 14 and the charging of the high-voltage battery 42, and terminates the charging of the high-voltage battery 42 using the warm-up operation of the fuel cell 14.

[0058] The second energy storage capacity may be the same as the first energy storage capacity, or it may be larger than the first energy storage capacity. A larger value for the second energy storage capacity is preferable.

[0059] Figure 3 is a flowchart showing an example of the operation of vehicle 1 in this embodiment. In step S1, the control unit 54 determines whether the conditions for starting the warm-up operation of the fuel cell 14 have been met. If the answer in step S1 is "NO", that is, if the conditions for starting the warm-up operation of the fuel cell 14 have not been met, the control unit 54 returns to step S1. On the other hand, if the answer in step S1 is "YES", that is, if the conditions for starting the warm-up operation of the fuel cell 14 have been met, the control unit 54 proceeds to step S2.

[0060] In step S2, the warm-up unit 58 of the control unit 54 starts the warm-up operation of the fuel cell 14 and proceeds to step S3. In step S3, the charging unit 60 of the control unit 54 starts charging the high-voltage battery 42 and proceeds to step S4.

[0061] In step S4, the control unit 54 determines whether the conditions for ending the warm-up operation of the fuel cell 14 have been met. If the answer in step S4 is "NO," that is, if the conditions for ending the warm-up operation of the fuel cell 14 have not been met, the control unit 54 returns to step S4. On the other hand, if the answer in step S4 is "YES," that is, if the conditions for ending the warm-up operation of the fuel cell 14 have been met, the control unit 54 proceeds to step S5.

[0062] In step S5, the control unit 54 determines whether the amount of charge stored in the high-voltage battery 42 is equal to or greater than the second amount of charge. If the answer in step S5 is "NO", that is, if the amount of charge stored in the high-voltage battery 42 is less than the second amount of charge, the control unit 54 returns to step S4. On the other hand, if the answer in step S5 is "YES", that is, if the amount of charge stored in the high-voltage battery 42 is equal to or greater than the second amount of charge, the control unit 54 proceeds to step S6.

[0063] In step S6, the warm-up unit 58 of the control unit 54 finishes warming up the fuel cell 14 and proceeds to step S7. In step S7, the charging unit 60 of the control unit 54 finishes charging the high-voltage battery 42, and the control unit 54 returns to the previous step. Note that the flowchart shown in Figure 3 is just one example, and the order of each step can be changed arbitrarily if the same effect can be achieved.

[0064] In such a vehicle 1, even if the conditions for ending the warm-up of the fuel cell 14 are met, if the amount of stored energy detected by the battery monitor 52 is less than the first stored energy, charging of the high-voltage battery 42 using the warm-up of the fuel cell 14 will continue. In other words, with such a vehicle 1, the amount of stored energy in the high-voltage battery 42 can be kept high. Furthermore, this ensures that the amount of stored energy necessary to start the driving system 10 is secured in the vehicle 1. In short, the vehicle 1 can transition to a state where it can be driven regardless of the surrounding environment.

[0065] Furthermore, in such a vehicle 1, when the conditions for ending the warm-up operation of the fuel cell 14 are met and the amount of stored energy detected by the battery monitor 52 reaches or exceeds the second stored energy level, charging of the high-voltage battery 42 using the warm-up operation of the fuel cell 14 is terminated. In other words, with such a vehicle 1, it is possible to maintain the amount of stored energy in the high-voltage battery 42 at or above the second stored energy level while suppressing excessive consumption of fuel gas (hydrogen gas) required for the warm-up operation of the fuel cell 14.

[0066] Furthermore, in such a vehicle 1, the start condition for warming up the fuel cell 14 is met when the temperature detected by the first temperature sensor 48 falls below a first temperature. In addition, in vehicle 1, the high-voltage battery 42 is charged when the warm-up of the fuel cell 14 begins. In other words, with such a vehicle 1, the amount of charge stored in the high-voltage battery 42 can be kept high even in environments where the first temperature sensor 48 detects a temperature below a first temperature (so-called low-temperature environments). Also, in vehicle 1, even if the surrounding environment of vehicle 1 is a low-temperature environment where the battery's discharge capacity decreases significantly, the amount of charge necessary to start the driving system 10 is secured. Therefore, vehicle 1 can transition to a drivable state even if the surrounding environment of vehicle 1 is a low-temperature environment.

[0067] Furthermore, in such a vehicle 1, the condition for ending the warm-up operation of the fuel cell 14 is met when the temperature detected by the first temperature sensor 48 reaches or exceeds the second temperature. In other words, with such a vehicle 1, after the warm-up operation of the fuel cell 14 is completed, that is, after the self-heating of the fuel cell 14 has ended, the residual heat of the fuel cell 14 itself can be used to remove the water generated during power generation.

[0068] 2. Variations This concludes the description of this embodiment. However, the specific configuration shown in this embodiment is merely an example, and the embodiments of the present invention are not limited to the configuration shown in this embodiment.

[0069] For the warm-up operation of the fuel cell 14 to be started, it may also be required that the warm-up operation of the fuel cell 14 has not been performed while the driving system 10 is stopped. In this case, the warm-up operation start condition for the fuel cell 14 is met when the warm-up operation of the fuel cell 14 has not been performed while the driving system 10 is stopped, and the temperature detected by the first temperature sensor 48 falls below the first temperature while the driving system 10 is stopped. In other words, the high-voltage battery 42 is charged only once using the warm-up operation of the fuel cell 14 while the driving system 10 is stopped. Therefore, in this case, it is possible to maintain a high charge level in the high-voltage battery 42 while suppressing excessive consumption of fuel gas (hydrogen gas) required for the warm-up operation of the fuel cell 14. [Explanation of Symbols]

[0070] 1 vehicle 12 Fuel cell systems 14 Fuel Cell 42 High-voltage batteries 58 Warm-up Operation Section 60 Live parts 62 Charging continuation section 48. First temperature sensor 50 Second temperature sensor 52 Battery Monitor

Claims

1. A fuel cell vehicle capable of performing a warm-up operation of the fuel cell by generating electricity from the fuel cell, A battery for driving, A charging unit that supplies the electricity generated by the fuel cell during the warm-up operation to the battery and charges the battery, A detection unit for detecting the amount of charge stored in the aforementioned battery, A fuel cell vehicle comprising: a charging continuation unit that, when the conditions for ending the warm-up operation are met, if the amount of stored energy detected by the detection unit is less than a first amount of stored energy, continues charging the battery using the warm-up operation.

2. The fuel cell vehicle according to claim 1, wherein the charging continuation unit terminates charging of the battery using the warm-up operation when the conditions for terminating the warm-up operation are met and the amount of stored energy detected by the detection unit becomes equal to or greater than the second amount of stored energy.

3. The fuel cell is equipped with a temperature detection unit for detecting the temperature of the fuel cell, The fuel cell vehicle according to claim 1, wherein the condition for starting the warm-up operation is met when the temperature detected by the temperature detection unit falls below a first temperature.

4. The fuel cell vehicle according to claim 3, wherein the condition for ending the warm-up operation is met when the temperature detected by the temperature detection unit reaches a second temperature or higher.

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