Fuel cell unit

Abstract

To provide a technique which enables power generation with the use of a first fuel cell stack and a second fuel cell stack even when one of a first air compressor and a second air compressor fails.SOLUTION: A fuel cell unit comprises a first air compressor, a first fuel cell stack, a first supply pipe, a second air compressor, a second fuel cell stack, a second supply pipe, a connection pipe, an on-off valve, and a control device. When the first air compressor and the second air compressor are determined to be in the normal condition, the control device causes the on-off valve to operate in a closed state. When one of the first air compressor and the second air compressor is not determined to be in the normal condition, the control device causes the on-off valve to operate in an open state. As a result, air can be supplied from the other normal one of the first air compressor and the second air compressor to the first fuel cell stack and the second fuel cell stack.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel cell unit.

Background Art

[0002] Patent Document 1 discloses a fuel cell unit including a first air compressor, a first fuel cell stack, a first supply pipe for supplying air from the first air compressor to the first fuel cell stack, a second air compressor, a second fuel cell stack, a second supply pipe for supplying air from the second air compressor to the second fuel cell stack, a connection pipe connecting the first supply pipe and the second supply pipe, an on-off valve provided in the connection pipe, and a control device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fuel cell unit of Patent Document 1, when the required output from the load of the fuel cell system becomes equal to or less than a threshold value, the control device operates the on-off valve in an open state, operates the first air compressor, and stops the operation of the second air compressor. In the fuel cell unit of Patent Document 1, no consideration is given to the case where one of the first air compressor and the second air compressor fails.

[0005] This specification provides a technology capable of generating power using the first fuel cell stack and the second fuel cell stack even when one of the first air compressor and the second air compressor fails.

Means for Solving the Problems

[0006] In a first aspect of the present technology, the fuel cell unit may include a first air compressor, a first fuel cell stack, a first supply pipe that supplies air from the first air compressor to the first fuel cell stack, a second air compressor, a second fuel cell stack, a second supply pipe that supplies air from the second air compressor to the second fuel cell stack, a connection pipe that connects the first supply pipe and the second supply pipe, an on-off valve provided in the connection pipe, and a control device. The control device determines whether the first air compressor is normal and whether the second air compressor is normal. When it is determined that the first air compressor and the second air compressor are normal, the on-off valve is operated in a closed state. When it is determined that one of the first air compressor and the second air compressor is not normal, the on-off valve is operated in an open state, so that air can be supplied from the normal other one of the first air compressor and the second air compressor to the first fuel cell stack and the second fuel cell stack.

[0007] According to the above configuration, when the control device determines that one of the first air compressor and the second air compressor is not normal, the on-off valve is operated in an open state. In this case, for example, when the first air compressor fails, air is supplied from the second air compressor to the first fuel cell stack and the second fuel cell stack. Also, when the second air compressor fails, air is supplied from the first air compressor to the first fuel cell stack and the second fuel cell stack. Therefore, even when one of the first air compressor and the second air compressor fails, power can be generated using the first fuel cell stack and the second fuel cell stack.

[0008] In a second aspect, in the first aspect described above, the control device specifies a first required air quantity of the first fuel cell stack based on a first required output of the first fuel cell stack, and specifies a second required air quantity of the second fuel cell stack based on a second required output of the second fuel cell stack. When it is determined that the first air compressor is not normal and the second air compressor is normal, a subtracted air quantity obtained by subtracting the second required air quantity from the maximum air quantity that the second air compressor can supply is specified. When the subtracted air quantity is equal to or greater than the first required air quantity, the on-off valve may be operated in the open state. When the subtracted air quantity is less than the first required air quantity, the on-off valve may be operated in the closed state.

[0009] If the on-off valve is operated in the open state when the subtracted air quantity is less than the first required air quantity, the second air quantity may become less than the second required air quantity. According to the above configuration, even when the first air compressor fails, the second air quantity supplied to the second air compressor can be made equal to the second required air quantity.

[0010] In a third aspect, in the first aspect described above, the fuel cell unit may further include a flow rate adjustment unit that adjusts the air quantity supplied to the first fuel cell stack and the air quantity supplied to the second fuel cell stack, a first flow rate sensor that detects the first air quantity supplied to the first fuel cell stack, and a second flow rate sensor that detects the second air quantity supplied to the second fuel cell stack. When it is determined that the first air compressor is not normal, the second air compressor is normal, and the subtracted air quantity is equal to or greater than the first required air quantity, the on-off valve may be operated in the open state, and the operations of the second air compressor and the flow rate adjustment unit may be controlled so that the first air quantity supplied to the first fuel cell stack becomes equal to the first required air quantity and the second air quantity supplied to the second fuel cell stack becomes equal to the second required air quantity.

[0011] According to the above configuration, even when the first air compressor fails, by controlling the operation of the flow rate adjustment unit, the first air volume can be made equal to the first required air volume, and the second air volume can be made equal to the second required air volume.

[0012] In a fourth aspect, in any one of the above first or second aspects, the fuel cell unit may further include a flow rate adjustment unit that adjusts the air volume supplied to the first fuel cell stack and the air volume supplied to the second fuel cell stack, a first flow rate sensor that detects the first air volume supplied to the first fuel cell stack, and a second flow rate sensor that detects the second air volume supplied to the second fuel cell stack. The power generation characteristics of the first fuel cell stack may be greater than those of the second fuel cell stack. When the first air compressor is not normal, the second air compressor is normal, and the on-off valve is operating in the open state, and the subtracted air volume is less than or equal to the first required air volume, the control device may control the operation of the flow rate adjustment unit so that the first air volume supplied to the first fuel cell stack is greater than the second air volume supplied to the second fuel cell stack.

[0013] When the first air volume and the second air volume are the same, the power generation amount of the first fuel cell stack with relatively large power generation characteristics is greater than the power generation amount of the second fuel cell stack with relatively small power generation characteristics. According to the above configuration, when the first air compressor is not normal, the second air compressor is normal, and the on-off valve is operating in the open state, and the subtracted air volume is less than or equal to the first required air volume, the first air volume becomes greater than the second air volume. Therefore, compared with a configuration in which the second air volume is greater than the first air volume, the power generation amount of the fuel cell unit can be increased.

[0014] In the fifth aspect, in any one of the first to fourth aspects, the fuel cell unit may further include a first check valve provided between the first air compressor and a connection portion where the connection pipe is connected to the first supply pipe in the first supply pipe, and a second check valve provided between the second air compressor and a connection portion where the connection pipe is connected to the second supply pipe in the second supply pipe.

[0015] According to the above configuration, for example, when the first air compressor fails, it is possible to prevent the air supplied from the second air compressor from flowing to the first air compressor side. Similarly, when the second air compressor fails, it is possible to prevent the air supplied from the first air compressor from flowing to the second air compressor side. Therefore, the amount of air supplied to the first fuel cell stack and the second fuel cell stack can be increased.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0017] (Embodiment) As shown in FIG. 1, the fuel cell unit 2 includes a first stack unit 10A, a second stack unit 10B, a unit connection pipe 12, and a control device 14. The fuel cell unit 2 is mounted on, for example, a fuel cell vehicle. The first stack unit 10A and the second stack unit 10B have the same configuration. Hereinafter, the first stack unit 10A will be described in detail as an example, and the detailed description of the second stack unit 10B will be omitted. For the reference numerals of the configurations common to the first stack unit 10A and the second stack unit 10B, "A" is added to the end of the configuration related to the first stack unit 10A, and "B" is added to the end of the configuration related to the second stack unit 10B. Also, for the names of the configurations common to the first stack unit 10A and the second stack unit 10B, "first" is added to the beginning of the configuration related to the first stack unit 10A, and "second" is added to the beginning of the configuration related to the second stack unit 10B.

[0018] The first stack unit 10A includes a first air compressor 20A, a first fuel cell stack 22A, a first supply pipe 24A, a first discharge pipe 26A, and a first connection pipe 28A. Hereinafter, the air compressor will be referred to as "ACP". Also, the fuel cell stack will be referred to as "FC stack".

[0019] The first ACP 20A supplies air containing oxygen to the first FC stack 22A. The first FC stack 22A generates electric power by reacting oxygen contained in the air supplied from the first ACP 20A with hydrogen supplied from a fuel tank (not shown).

[0020] The first supply pipe 24A supplies air from the first ACP 20A to the first FC stack 22A. The upstream end of the first supply pipe 24A is connected to the first ACP 20A, and the downstream end of the first supply pipe 24A is connected to the first FC stack 22A. The first supply pipe 24A is provided with a first check valve 30A, a first shut-off valve 32A, and a first flow sensor 34A. The first check valve 30A is provided upstream of the first shut-off valve 32A. The first shut-off valve 32A opens and closes the flow path in the first supply pipe 24A. The first flow sensor 34A is provided upstream of the first check valve 30A and the first shut-off valve 32A. The first flow sensor 34A detects the amount of air supplied to the first FC stack 22A (hereinafter referred to as "the first air amount"). Hereinafter, the amount of air detected by the second flow sensor 34B of the second stack unit 10B is referred to as "the second air amount".

[0021] The first discharge pipe 26A recovers the air after the reaction discharged from the first FC stack 22A. The upstream end of the first discharge pipe 26A is connected to the first FC stack 22A, and the other end of the first discharge pipe 26A is connected to the discharge location of the air and water after the reaction (not shown). The first discharge pipe 26A is provided with a first flow control valve 36A.

[0022] The first connection pipe 28A connects the first supply pipe 24A and the first discharge pipe 26A. The upstream end of the first connection pipe 28A is connected to the first supply pipe 24A between the first check valve 30A and the first shut-off valve 32A. The downstream end of the first connection pipe 28A is connected to the first discharge pipe 26A downstream of the first flow control valve 36A. The first connection pipe 28A is provided with a first diverter valve 38A.

[0023] Note that the first stack unit 10A and the second stack unit 10B have the same configuration, but are configured such that the power generation characteristics of the first FC stack 22A are higher than those of the second FC stack 22B.

[0024] The unit connection pipe 12 connects the first supply pipe 24A of the first stack unit 10A and the second supply pipe 24B of the second stack unit 10B. One end of the unit connection pipe 12 is connected to the first supply pipe 24A on the upstream side of the first check valve 30A and on the downstream side of the connection portion between the first supply pipe 24A and the first connection pipe 28A. That is, the first check valve 30A is provided between the first air compressor 20A and the connection portion where the unit connection pipe 12 is connected to the first supply pipe 24A. The other end of the unit connection pipe 12 is connected to the second supply pipe 24B on the upstream side of the second check valve 30B and on the downstream side of the connection portion between the second supply pipe 24B and the second connection pipe 28B. An on-off valve 40 is provided in the unit connection pipe 12. The on-off valve 40 opens and closes the flow path in the unit connection pipe 12.

[0025] The control device 14 is configured by using a computer including a CPU, a ROM, and a RAM. The control device 14 controls the operations of the components of the fuel cell unit 2.

[0026] (First power generation process; Figure 2) Referring to Figure 2, the first power generation process executed by the control device 14 will be described. In the start state of the first power generation process, the first sealing valve 32A and the second sealing valve 32B are in the open state, and the on-off valve 40 is in the closed state. Also, when starting the power generation process, the control device 14 drives the first ACP 20A, the first FC stack 22A, the second ACP 20B, and the second FC stack 22B.

[0027] In S10, the control device 14 determines the first required air quantity of the first ACP 20A and the second required air quantity of the second ACP 20B. Specifically, the control device 14 uses the required output corresponding to the required power of the traveling motor (not shown) or the like to determine the first required output of the first FC stack 22A and the second required output of the second FC stack 22B. Next, the control device 14 uses each of the first required output and the second required output to determine the first required air quantity and the second required air quantity. The first required air quantity is the air quantity to be supplied to the first FC stack 22A, and the second required air quantity is the air quantity to be supplied to the second FC stack 22B. Next, the control device 14 drives the first ACP 20A so that the first air quantity becomes the first required air quantity, and drives the second ACP 20B so that the second air quantity becomes the second required air quantity.

[0028] In S20, the control device 14 determines whether the second ACP 20B is normal. When the control device 14 determines that the second ACP 20B is normal (YES in S20), it proceeds to S60. On the other hand, when the control device 14 determines that the second ACP 20B is not normal (failed) (NO in S20), it proceeds to S30.

[0029] In S30, the control device 14 determines whether the first subtracted air quantity is greater than or equal to the second required air quantity. The first subtracted air quantity is obtained by subtracting the first required air quantity from the first maximum air quantity, which is the maximum air quantity that the first ACP 20A can supply. When the control device 14 determines that the first subtracted air quantity is greater than or equal to the second required air quantity (YES in S30), it proceeds to S32. On the other hand, when the control device 14 determines that the first subtracted air quantity is less than the second required air quantity (NO in S30), it proceeds to S50.

[0030] In S32, the control device 14 shifts the on-off valve 40 to the open state. Thereby, the air from the first ACP 20A is supplied to the first FC stack 22A and the second FC stack 22B. Also, at the time of S32, when the second FC stack 22B is stopped, the control device 14 drives the second FC stack 22B.

[0031] In S34, the control device 14 adjusts the opening degrees of the first flow rate adjustment valve 36A and the second flow rate adjustment valve 36B so that the first air amount becomes the first required air amount and the second air amount becomes the second required air amount.

[0032] The processing contents of S40, S42, and S44 are the same as the processing contents of S10, S30, and S34, respectively. When it is determined as YES in S42, the control device 14 proceeds to S42, and when it is determined as NO in S40, the control device 14 proceeds to S50. Further, when S44 ends, the control device 14 returns to S40.

[0033] Also, in S50, the control device 14 shifts the on-off valve 40 to the closed state. As a result, the air from the first ACP 20A is supplied only to the first FC stack 22A. Further, at the time of S50, when the second FC stack 22B is being driven, the control device 14 stops the second FC stack 22B.

[0034] The processing content of S52 is the same as the processing content of S10. When S52 ends, the control device 14 returns to S30.

[0035] Also, when it is determined as NO in S20, in S60, the control device 14 determines whether the first ACP 20A is normal. When the control device 14 determines that the first ACP 20A is normal (YES in S60), it returns to S10. On the other hand, when the control device 14 determines that the first ACP 20A is not normal (failed) (NO in S60), it proceeds to S62.

[0036] In S62, the control device 14 executes a second power generation process (see FIG. 3). The second power generation process is a process for generating power using the first FC stack 22A and the second FC stack 22B in a state where the first ACP 20A is not normal.

[0037] (Second power generation process; FIG. 3) Referring to FIG. 3, the second power generation process executed in S62 of FIG. 2 will be described.

[0038] In S70, the control device 14 determines whether the second subtracted air quantity is greater than or equal to the first required air quantity. The second subtracted air quantity is obtained by subtracting the second required air quantity from the second maximum air quantity, which is the maximum air quantity that the second ACP 20B can supply. When the second subtracted air quantity is greater than or equal to the first required air quantity (YES in S70), the control device 14 proceeds to S72. On the other hand, when the second subtracted air quantity is less than the first required air quantity (NO in S70), the control device 14 proceeds to S100.

[0039] In S72, the control device 14 shifts the on-off valve 40 to the open state. Thereby, the air from the second ACP 20B is supplied to the first FC stack 22A and the second FC stack 22B. Also, at the time of S72, when the first FC stack 22A is stopped, the control device 14 drives the first FC stack 22A.

[0040] The processing content of S74 is the same as the processing content of S34 in FIG. 2. The processing contents of S80, S82, and S84 are the same as the processing contents of S10, S30, and S34 in FIG. 2, respectively. When it is determined as YES in S82, the control device 14 proceeds to S84, and when it is determined as NO in S82, the control device 14 proceeds to S90. Also, when S84 ends, the control device 14 returns to S80.

[0041] In S90, the control device 14 adjusts the opening degrees of the first flow rate adjustment valve 36A and the second flow rate adjustment valve 36B so that the air quantity supplied to the first FC stack 22A with high power generation characteristics increases. That is, the air supplied from the second ACP 20B is preferentially supplied to the first FC stack 22A rather than the second FC stack 22B. When S90 ends, the control device 14 returns to S80.

[0042] Also, when it is determined that NO at S70, at S100, the control device 14 shifts the on-off valve 40 to the closed state. Thereby, the air from the second ACP 20B is supplied only to the second FC stack 22B. Further, when the first FC stack 22A is driving at the time of S100, the control device 14 stops the first FC stack 22A.

[0043] The processing content of S102 is the same as the processing content of S10 in FIG. 2. When the processing of S102 ends, the control device 14 returns to S70.

[0044] (Effect of this embodiment) As described above, the fuel cell unit 2 includes a first ACP 20A, a first FC stack 22A, a first supply pipe 24A that supplies air from the first ACP 20A to the first FC stack 22A, a second ACP 20B, a second FC stack 22B, a second supply pipe 24B that supplies air from the second ACP 20B to the second FC stack 22B, a unit connection pipe 12 (an example of a "connection pipe") that connects the first supply pipe 24A and the second supply pipe 24B, an on-off valve 40 provided in the unit connection pipe 12, and a control device 14. The control device 14 determines whether the first ACP 20A is normal and whether the second ACP 20B is normal (S20, S60 in FIG. 2). When it is determined that the first ACP 20A and the second ACP 20B are normal (YES in S20 and YES in S60), the on-off valve 40 is operated in the closed state. When it is determined that one of the first ACP 20A and the second ACP 20B is not normal (NO in S20 or NO in S60), the on-off valve 40 is operated in the open state, whereby air can be supplied from the normal other one of the first ACP 20A and the second ACP 20B to the first FC stack 22A and the second FC stack 22B (S32, or S72 in FIG. 3).

[0045] According to the above configuration, when the control device 14 determines that one of the first ACP 20A and the second ACP 20B is abnormal, the control device 14 operates the on-off valve 40 in the open state. In this case, for example, when the first ACP 20A fails, air is supplied from the second ACP 20B to the first FC stack 22A and the second FC stack 22B. Also, when the second ACP 20B fails, air is supplied from the first ACP 20A to the first FC stack 22A and the second FC stack 22B. Therefore, even when one of the first ACP 20A and the second ACP 20B fails, power generation can be performed using the first FC stack 22A and the second FC stack 22B.

[0046] Further, the control device 14 specifies the first required air amount of the first FC stack 22A based on the first required output of the first FC stack 22A, and specifies the second required air amount of the second FC stack 22B based on the second required output of the second FC stack 22B. When it is determined that the first ACP 20A is abnormal and the second ACP 20B is normal (NO in S60 of FIG. 2), the control device 14 specifies a subtracted air amount obtained by subtracting the second required air amount from the second maximum air amount that the second ACP 20B can supply. When the subtracted air amount is equal to or greater than the first required air amount (YES in S70 of FIG. 3), the control device 14 operates the on-off valve 40 in the open state. When the subtracted air amount is less than the first required air amount (NO in S70), the control device 14 operates the on-off valve 40 in the closed state (S100).

[0047] If the on-off valve 40 is operated in the open state when the subtracted air amount is less than the first required air amount, the second air amount may become less than the second required air amount. According to the above configuration, even when the first ACP 20A fails, the second air amount supplied to the second ACP 20B can be made equal to the second required air amount.

[0048] Further, the fuel cell unit 2 further includes flow rate adjustment valves 36A and 36B (an example of a "flow rate adjustment unit") that adjust the amount of air supplied to the first FC stack 22A and the amount of air supplied to the second FC stack 22B, a first flow rate sensor 34A that detects the first amount of air supplied to the first FC stack 22A, and a second flow rate sensor 34B that detects the second amount of air supplied to the second FC stack 22B. When the control device 14 determines that the first ACP 20A is abnormal, the second ACP 20B is normal, and the subtracted air amount is equal to or greater than the first required air amount (NO in S60 of FIG. 2, YES in S70 of FIG. 3), the control device 14 operates the on-off valve 40 in the open state, and controls the operations of the second ACP 20B and the flow rate adjustment valves 36A and 36B so that the first amount of air supplied to the first FC stack 22A becomes the first required air amount and the second amount of air supplied to the second FC stack 22B becomes the second required air amount (S72).

[0049] According to the above configuration, even when the first ACP 20A fails, by controlling the operations of the flow rate adjustment valves 36A and 36B, the first amount of air can be made equal to the first required air amount and the second amount of air can be made equal to the second required air amount.

[0050] Further, the fuel cell unit 2 further includes flow rate adjustment valves 36A and 36B (an example of a "flow rate adjustment unit") that adjust the amount of air supplied to the first FC stack 22A and the amount of air supplied to the second FC stack 22B, a first flow rate sensor 34A that detects the first amount of air supplied to the first FC stack 22A, and a second flow rate sensor 34B that detects the second amount of air supplied to the second FC stack 22B. The power generation characteristics of the first FC stack 22A are greater than those of the second FC stack 22B. When the control device 14 determines that the first ACP 20A is abnormal, the second ACP 20B is normal, and the on-off valve 40 is operating in the open state (NO in S60 of FIG. 2, S72 in FIG. 3), and when the subtracted air amount is equal to or less than the first required air amount (YES in S82), the control device 14 controls the operations of the second ACP 20B and the flow rate adjustment valves 36A and 36B so that the first amount of air is greater than the second amount of air (S90).

[0051] When the first air amount and the second air amount are the same, the power generation amount of the first FC stack 22A with relatively large power generation characteristics is larger than the power generation amount of the second FC stack 22B with relatively small power generation characteristics. According to the above configuration, when the first ACP 20A is abnormal, the second ACP 20B is normal, and the on-off valve 40 is operating in the open state, if the subtraction air amount becomes equal to or less than the first required air amount, the first air amount becomes larger than the second air amount. Therefore, compared with the configuration in which the second air amount is larger than the first air amount, the power generation amount of the fuel cell unit 2 can be increased.

[0052] Also, the fuel cell unit 2 further includes a first check valve 30A provided between the first air compressor 20A and the connection portion where the unit connection pipe 12 is connected to the first supply pipe 24A in the first supply pipe 24A, and a second check valve 30B provided between the second air compressor 20B and the connection portion where the unit connection pipe 12 is connected to the second supply pipe 24B in the second supply pipe 24B.

[0053] According to the above configuration, for example, when the first ACP 20A fails, it is possible to prevent the air supplied from the second ACP 20B from flowing to the first ACP 20A side. Also, when the second ACP 20B fails, it is possible to prevent the air supplied from the first ACP 20A from flowing to the second ACP 20B side. Therefore, the air amount supplied to the first FC stack 22A and the second FC stack 22B can be increased.

[0054] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

[0055] (First Modification Example) In the above-described embodiment, two stack units 10A and 10B are arranged in parallel. The number of stack units arranged in parallel is not limited to two. For example, as shown in FIG. 4, four stack units 110A to 110D may be arranged in parallel. In FIG. 4, the same reference numerals are given to the components common to the embodiment. Also, for ease of viewing, the reference numerals for the respective components of the stack units 110B to 110D are omitted. The fuel cell unit 102 in FIG. 4 includes four stack units 110A to 110D and a unit connection pipe 112. The unit connection pipe 112 includes a first pipe 114 and a branch pipe 116A. One end of the branch pipe 116A is connected to the first supply pipe 24A, and the other end of the branch pipe 116A is connected to the first pipe 114. An on-off valve 140A for opening and closing the flow path in the branch pipe 116A is provided in the branch pipe 116A. For example, when the control device 14 determines that the first ACP 20A is not normal, the on-off valve 140A is set to the open state. Thereby, the air from the air compressors of the stack units 110B to 110D is supplied to the first FC stack 22A. In another modification example, the number of stack units arranged in parallel may be three, or may be five or more.

[0056] (Second Modification Example) When the control device 14 determines NO in S20, the control device 14 may execute the process of S32 regardless of whether the first subtracted air amount is the second required air amount. In this modification example, S30, S42, S44, S50, and S52 in FIG. 2 can be omitted. Also, when the control device 14 determines NO in S60, the control device 14 may execute the process of S72 in FIG. 3 regardless of whether the second subtracted air amount is the first required air amount. In this modification example, 70, S82, S84, S90, S100, and S102 in FIG. 3 can be omitted.

[0057] (Third Modification Example) The fuel cell unit 2 may not have the flow rate sensors 34A and 34B and the flow rate adjustment valves 36A and 36B. In this modification example, S34 and S44 in FIG. 2 and S74 and S84 in FIG. 3 can be omitted.

[0058] (Fourth Modification Example) Instead of the flow rate sensors 34A and 34B, the fuel cell unit 2 may include a pressure loss measurement unit for calculating the pressure loss of the first stack unit 10A and the pressure loss of the second stack unit 10B, respectively. The pressure loss measurement unit is, for example, a member for measuring AC impedance. In this case, the fuel cell unit 2 adjusts the opening degrees of the flow rate adjustment valves 36A and 36B based on the information detected by the pressure loss measurement unit.

[0059] (Fifth Modification Example) The power generation characteristics of the first FC stack 22A and the power generation characteristics of the second FC stack 22B may be the same. In this modification example, S90 in FIG. 3 can be omitted.

[0060] (Sixth Modification Example) When it is determined as NO in S70, the control device 14 may execute S72 and S90 instead of S100. That is, when the first ACP 20A fails, the control device 14 may always supply the air supplied from the second ACP 20B to the first FC stack 22A preferentially over the second FC stack 22B.

[0061] Also, the technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of purposes simultaneously, and achieving one of those purposes itself has technical utility.

Explanation of Reference Numerals

[0062] 2: Fuel cell unit, 10A: First stack unit, 10B: Second stack unit, 12: Unit connection pipe, 14: Control device, 20A: First air compressor, 20B: Second air compressor, 22A: First fuel cell stack, 22B: Second fuel cell stack, 24A: First supply pipe, 24B: Second supply pipe, 26A: First discharge pipe, 28A: First connection pipe, 28B: Second connection pipe, 30A: First check valve, 30B: Second check valve, 32A: First shut-off valve, 32B: Second shut-off valve, 34A: First flow sensor, 34B: Second flow sensor, 36A: First flow control valve, 36B: Second flow control valve, 38A: First diverter valve, 40: On-off valve

Claims

1. A fuel cell unit, comprising: a first air compressor; a first fuel cell stack; a first supply pipe for supplying air from the first air compressor to the first fuel cell stack; a second air compressor; a second fuel cell stack; a second supply pipe for supplying air from the second air compressor to the second fuel cell stack; a connection pipe connecting the first supply pipe and the second supply pipe; a on-off valve provided in the connection pipe; a control device, wherein the control device: determines whether the first air compressor is normal and whether the second air compressor is normal; when it is determined that the first air compressor and the second air compressor are normal, operates the on-off valve in a closed state; when it is determined that one of the first air compressor and the second air compressor is not normal, operates the on-off valve in an open state, so that air can be supplied from the normal other one of the first air compressor and the second air compressor to the first fuel cell stack and the second fuel cell stack. A fuel cell unit.

2. The control device: specifies a first required air amount of the first fuel cell stack based on a first required output of the first fuel cell stack; specifies a second required air amount of the second fuel cell stack based on a second required output of the second fuel cell stack; when it is determined that the first air compressor is not normal and the second air compressor is normal, specifies a subtracted air amount obtained by subtracting the second required air amount from the maximum air amount that the second air compressor can supply; when it is determined that the subtracted air amount is greater than or equal to the first required air amount, operates the on-off valve in the open state; when the subtracted air amount is less than the first required air amount, operates the on-off valve in the closed state. The fuel cell unit according to Claim 1.

3. a flow rate adjustment unit for adjusting the air amount supplied to the first fuel cell stack and the air amount supplied to the second fuel cell stack; a first flow rate sensor for detecting a first air amount supplied to the first fuel cell stack; a second flow rate sensor for detecting a second air amount supplied to the second fuel cell stack, and further comprising: wherein the control device: When it is determined that the first air compressor is not normal, the second air compressor is normal, and the subtracted air volume is equal to or greater than the first required air volume, the on-off valve is operated in the open state, and the first air volume supplied to the first fuel cell stack becomes the first required air volume, and the second air volume supplied to the second fuel cell stack becomes the second required air volume, and the operations of the second air compressor and the flow rate adjustment unit are controlled. The fuel cell unit according to claim 2.

4. A flow rate adjustment unit that adjusts the air volume supplied to the first fuel cell stack and the air volume supplied to the second fuel cell stack; A first flow rate sensor that detects the first air volume supplied to the first fuel cell stack; A second flow rate sensor that detects the second air volume supplied to the second fuel cell stack, and further includes: The power generation characteristics of the first fuel cell stack are greater than the power generation characteristics of the second fuel cell stack. The control device is: When the first air compressor is not normal, the second air compressor is normal, and the subtracted air volume is equal to or less than the first required air volume in a state where the on-off valve is operating in the open state, the first air volume supplied to the first fuel cell stack is greater than the second air volume supplied to the second fuel cell stack, and the operation of the flow rate adjustment unit is controlled. The fuel cell unit according to claim 2.

5. A first check valve provided between the first air compressor and the connection portion where the connection pipe is connected to the first supply pipe in the first supply pipe; A second check valve provided between the second air compressor and the connection portion where the connection pipe is connected to the second supply pipe in the second supply pipe; The fuel cell unit according to claim 1, further comprising:

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