Fuel battery

Abstract

To provide a technique for suppressing deterioration of a power generation performance of a fuel battery.SOLUTION: A fuel battery comprises: first supply means of supplying an oxydant agent gas to a fuel battery stack; second supply means of supplying a cooling gas to a fuel battery stack; detection means of detecting an in-surface temperature of the fuel battery cell; and a control device that controls the first and second supply means. The control device starts a supply of the oxydant agent gas by the first supply means while stopping the supply of the cooling gas by the second supply means at a time of starting a low temperature of the fuel battery stack, executes a low-temperature starting processing for increasing a temperature of the fuel battery cell, uses a temperature increase speed of an in-surface temperature, and determines a stop of the low-temperature starting processing.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This specification discloses a fuel cell having a plurality of fuel cell stacks laminated along a specific direction.

Background Art

[0002] Patent Document 1 describes a control unit for controlling a fuel cell having a plurality of stacked fuel cells. When the control unit detects a decrease in the cell voltage, after stopping the power generation by the fuel cell, it switches the drive source of the load such as a motor from the fuel cell to the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above fuel cell is cooled, for example, by a cooling gas flowing between two adjacent fuel cells. However, when the fuel cell starts under low temperature conditions, the product liquid generated by the reaction of the fuel gas and the oxidant gas in the fuel cell cell stays. The retention of the product liquid is one of the causes of the decrease in the power generation performance of the fuel cell. This specification provides a technique for suppressing the decrease in the power generation performance of the fuel cell.

Means for Solving the Problems

[0005] The fuel cell disclosed in this specification has a plurality of fuel cell cells stacked along a certain direction, and is an air-cooled type cooled by a cooling gas flowing between two adjacent fuel cell cells. The fuel cell includes a first supply means for supplying an oxidant gas to the fuel cell stack, a second supply means for supplying the cooling gas to the fuel cell stack, a detection means provided in the fuel cell cell for detecting the in-plane temperature of the fuel cell cell, and a control device for controlling the first supply means and the second supply means. The control device executes a low-temperature start-up process for raising the temperature of the fuel cell cell by starting the supply of the oxidant gas by the first supply means while stopping the supply of the cooling gas by the second supply means when starting up at a low temperature, and is configured to determine the stop of the low-temperature start-up process by using the rate of temperature rise of the in-plane temperature detected by the detection means.

[0006] According to the above configuration, the temperature of the fuel cell cell is raised by the low-temperature start-up process executed during low-temperature start-up. The temperature rise of the fuel cell cell promotes the discharge of the generated liquid staying in the fuel cell cell. By promoting the discharge of the generated liquid, it is possible to suppress the deterioration of the power generation performance of the fuel cell caused by the retention of the generated liquid. And the low-temperature start-up process can be stopped at an appropriate timing using the rate of temperature rise of the in-plane temperature. Although not particularly limited, as an example of the detection means, temperature sensors may be provided in each of the low-temperature region and the high-temperature region in the plan view of the fuel cell cell.

[0007] Details of the technology disclosed in this specification and further improvements will be described in the following "Mode for Carrying Out the Invention".

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] (Configuration of System 2; Figure 1) System 2 (for example, a vehicle) includes a fuel cell 10, a battery 12, a load 14, an auxiliary machine 16, and a control device 18. Each of the units 12, 14, 16, and 18 is connected in parallel to each other via a power line 4. The load 14 is, for example, a motor. The auxiliary machine 16 is a device such as an air blower. The electric power generated by the fuel cell 10 is supplied to each of the units 14, 16, and 18 via the power line 4. Note that the fuel cell 10 disclosed in this specification can also be adopted in other systems other than System 2.

[0010] The control device 18 is a device that controls the fuel cell 10. The control device 18 is communicably configured with a voltage sensor 13 that detects the battery voltage, which is the output voltage of the battery 12, and a temperature sensor 19 that detects the outside air temperature.

[0011] (Configuration of Fuel Cell 10; Figures 2, 3, 4, 5) The fuel cell 10 includes a fuel cell stack 20, an oxidant supply device 22, a fuel supply device 24, and a cooling gas supply device 26. The fuel cell stack 20 has a plurality of fuel cells 30 (see Figure 3) stacked along a certain direction, and is an air-cooled device cooled by the cooling gas flowing between two adjacent fuel cells 30. The oxidant supply device 22 is a device that supplies oxidant gas to the fuel cell stack 20, and is, for example, a blower such as a fan. The oxidant gas is, for example, air containing oxygen. The fuel supply device 24 is a device that supplies fuel gas to the fuel cell stack 20, and is, for example, a blower. The fuel gas is, for example, hydrogen gas. The cooling gas supply device 26 is a device that supplies cooling gas to the fuel cell stack 20, and is, for example, a blower. The cooling gas is, for example, air.

[0012] As shown in FIG. 3, the fuel cell 30 includes a first separator 32, a second separator 34, and a resin frame 36. Each of the parts 32, 34, and 36 is laminated along the Y-axis direction among the XYZ coordinates shown in FIG. 3. Specifically, the resin frame 36 is sandwiched between the first separator 32 and the second separator 34 in the Y-axis direction.

[0013] The resin frame 36 includes a membrane electrode assembly. The membrane electrode assembly is an assembly in which an ion exchange membrane is sandwiched between two electrodes (i.e., a positive electrode and a negative electrode). The membrane electrode assembly conducts ions between a fuel gas and an oxidant gas, thereby generating electricity.

[0014] A fuel gas flows between the first separator 32 and the resin frame 36 along the negative X-axis direction. The fuel gas flows in from an intake port 32a formed at the end on the positive X-axis side of the first separator 32 and flows out from an exhaust port 32b formed at the end on the negative X-axis side of the first separator 32.

[0015] An oxidant gas flows between the second separator 34 and the resin frame 36 along the positive X-axis direction. The oxidant gas flows in from an intake port 34a formed at the end on the negative X-axis side of the second separator 34 and flows out from an exhaust port 34b formed at the end on the positive X-axis side of the second separator 34.

[0016] A cooling plate 40 that forms a flow path for a cooling gas is disposed between two adjacent fuel cells 30. The cooling plate 40 is a metal plate and is processed into a corrugated shape.

[0017] As shown in FIG. 4, the cooling gas passes between two adjacent fuel cells 30 along the positive Z-axis direction. The range R1 on the negative Z-axis side in the plan view of the fuel cell 30 is the upstream side of the flow path of the cooling gas, and the range R2 on the positive Z-axis side in the plan view of the fuel cell 30 is the downstream side of the flow path of the cooling gas. The upstream range R1 of the cooling gas is cooler than the downstream range R2 of the cooling gas. The range R1 is at a lower temperature compared to the range R2. A temperature sensor 50 for detecting the temperature on the low-temperature side is provided in the range R1, and a temperature sensor 52 for detecting the temperature on the high-temperature side is provided in the range R2.

[0018] In the fuel cell 30, a product liquid is generated by the reaction of the fuel gas and the oxidant gas. The product liquid is, for example, water. Usually, the product liquid is discharged from the exhaust port 34b of the second separator 34 to the outside of the fuel cell 30. However, when the operation of the fuel cell 10 continues under a low-temperature situation such as below the freezing point, the product liquid stays in the fuel cell 30. For example, because the product liquid freezes. The retention of the product liquid is one of the causes of the deterioration of the power generation performance of the fuel cell 10, and power generation in a state where the product liquid stays is not preferable.

[0019] The control device 18 executes the process of FIG. 5 in order to suppress the deterioration of the power generation performance under a low-temperature situation. The process of FIG. 5 is started, for example, triggered by the startup switch of the system 2 being turned on under a low-temperature situation. Whether it is a low-temperature situation or not is determined based on, for example, the outside air temperature measured by the temperature sensor 19. Note that the conditions for determining whether it is a low-temperature situation or not are not particularly limited.

[0020] In S20, the control device 18 detects the detected temperature by the temperature sensor 19, that is, the outside air temperature. In S22, the control device 18 detects the battery voltage by the voltage sensor. In S24, the control device 18 calculates the calorific value of the fuel cell stack 20 required for the low-temperature start-up process based on the detected temperature in S20. In S26, the control device 18 calculates the supply amount of the oxidant gas required for the low-temperature start-up process based on the calorific value calculated in S22 and the battery voltage detected in S22. In S28, the control device 18 controls the oxidant supply device 22 based on the supply amount calculated in S26. In the low-temperature start-up process, the fuel cell 30 is heated up by operating the oxidant supply device 22 while stopping the operation of the cooling gas supply device 26. For example, a comparative example is assumed in which the oxidant supply device 22 is controlled with a predetermined supply amount without executing the processes of S20 to S26. In this comparative example, the predetermined supply amount may be excessive or too small for the low-temperature situation. On the other hand, by calculating the supply amount in the processes of S20 to S26, the oxidant supply device 22 can be controlled with a supply amount suitable for the actual situation. In a modified example, the configuration of the above comparative example may be adopted.

[0021] In S30, the control device 18 determines whether the decrease in the power generation performance of the fuel cell 30 has recovered according to the temperature rise rate of the fuel cell 30. For example, when the rising rate of the detected temperature of the temperature sensor 50 in the range R1 exceeds a predetermined threshold value, the control device 18 determines that the decrease in the power generation performance has recovered. When the control device 18 determines that the decrease in the power generation performance has recovered (YES in S30), the low-temperature start-up process is terminated.

[0022] (Effect) According to the configuration of this embodiment, the fuel cell 30 is heated up by the low-temperature start-up process (S10 in FIG. 5) executed during low-temperature start-up. The heating of the fuel cell 30 promotes the discharge of the generated liquid staying in the fuel cell 30. By promoting the discharge of the generated liquid, it is possible to suppress the deterioration of the power generation performance of the fuel cell 10 caused by the retention of the generated liquid. Then, using the rising speed of the detected temperature of the temperature sensor 50, the power generation state of the fuel cell 30 is estimated, and when it is determined that the deterioration of the power generation performance has recovered (YES in S30), the low-temperature start-up process can be stopped. That is, the low-temperature start-up process can be stopped at an appropriate timing.

[0023] (Another aspect of the low-temperature start-up process; FIG. 6) In the low-temperature start-up process, the fuel cell 30 is heated up. However, a situation is assumed in which the temperature on the high-temperature side of the fuel cell 30 exceeds a predetermined allowable temperature THmax before the retention of the generated liquid is eliminated. In the aspect shown in FIG. 6, the control device 18 monitors not only the detected temperature T1 in the low-temperature range R1 by the temperature sensor 50 but also the detected temperature T2 in the high-temperature range R2 by the temperature sensor 52 in the low-temperature start-up process. At time t5, while the detected temperature T2 on the high-temperature side exceeds the allowable temperature THmax, the rising speed of the detected temperature T1 on the low-temperature side does not exceed a predetermined threshold for determining the recovery of the deterioration of the power generation performance. The control device 18 temporarily stops the operation of the oxidant supply device 22 or reduces the supply amount of the oxidant gas by the oxidant supply device 22 at time t5. As a result, the detected temperatures T1 and T2 decrease. Then, the control device 18 returns the supply amount of the oxidant gas by the oxidant supply device 22 at time t6 after a predetermined period has elapsed from time t5. As a result, the fuel cell 30 is heated up again, and before the detected temperature T2 on the high-temperature side exceeds the allowable temperature THmax, the rising speed of the detected temperature T1 on the low-temperature side exceeds a predetermined threshold. According to this aspect, the low-temperature start-up process can be executed within a range where the temperature of the fuel cell 30 does not exceed the allowable temperature THmax.

[0024] (Corresponding relationship) The fuel cell 10, the Y-axis direction, and the battery 12 are examples of "fuel cell", "specific direction", and "battery", respectively. The fuel cell stack 20 and the plurality of fuel cell cells 30 are examples of "fuel cell stack" and "plurality of fuel cell cells", respectively. The control device 18, the oxidant supply device 22, and the cooling gas supply device 26 are examples of "control device", "first supply means", and "second supply means", respectively. The temperature sensors 50 and 52 are examples of "detection means". The low-temperature start-up process in FIG. 5 is an example of "low-temperature start-up process".

[0025] Hereinafter, points to note regarding the technology shown in the embodiments will be described. The fuel cell 10 may not include the temperature sensor 52. In this modification, the temperature sensor 50 is an example of "detection means".

Explanation of Reference Numerals

[0026] 2: System, 4: Power line, 10: Fuel cell, 12: Battery, 13: Voltage sensor, 14: Load, 16: Auxiliary machine, 18: Control device, 19: Temperature sensor, 20: Fuel cell stack, 22: Oxidant supply device, 24: Fuel supply device, 26: Cooling gas supply device, 30: Fuel cell cell, 32: First separator, 32a: Intake port, 32b: Exhaust port, 34: Second separator, 34a: Intake port, 34b: Exhaust port, 36: Resin frame, 40: Cooling plate, 50: Temperature sensor, 52: Temperature sensor,

Claims

【Claim 1】 An air-cooled fuel cell stack having a plurality of fuel cells stacked along a certain direction and cooled by a cooling gas flowing between two adjacent fuel cells; First supply means for supplying an oxidant gas to the fuel cell stack; Second supply means for supplying the cooling gas to the fuel cell stack; Detection means provided in the fuel cell for detecting the in-plane temperature of the fuel cell; A control device for controlling the first supply means and the second supply means; Comprising: When starting the fuel cell stack at a low temperature, the control device executes a low-temperature start-up process of raising the temperature of the fuel cell by starting the supply of the oxidant gas by the first supply means while stopping the supply of the cooling gas by the second supply means; It is configured to determine the stop of the low-temperature start-up process by using the rate of temperature rise of the in-plane temperature detected by the detection means. Fuel cell.

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