Fuel cell unit

Abstract

To preferably avoid a decrease in power generation capacity caused by water retention in a first gas flow path and a second gas flow path, without reducing the degree of freedom in designing a power generation portion.SOLUTION: When a control unit 9 generates electricity in a fuel battery cell 10, the control unit controls switching valves 7a to 7d to operate a suction pump 3 while allowing air to flow into an air intake port 11b and air to be exhausted from an exhaust port 11c, and when a pre-defined "first condition" is satisfied, the control unit continues operating the suction pump 3 while controlling the switching valves 7a to 7d to regulate the flow of air into the air intake port 11b and the exhaust of air from the exhaust port 11c, and then, when a pre-defined "second condition" is satisfied, the control unit controls the switching valves 7a to 7d to allow air to flow into the air intake port 11b and air to be exhausted from the exhaust port 11c.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fuel cell unit configured to generate electricity by reacting a first gas that is caused to flow through a first gas flow path in a first separator and a second gas that is caused to flow through a second gas flow path in a second separator via a membrane electrode assembly, the fuel cell unit including a power generation unit formed by laminating and integrating a first separator, a second separator, a membrane electrode assembly, and the like.

Background Art

[0002] As this type of fuel cell unit, a unit including a fuel cell stack in which a plurality of fuel cells (power generation cells) configured by sandwiching an electrolyte membrane / electrode structure (MEA with a resin frame: hereinafter, simply referred to as "MEA" including the frame material) between a pair of separators (a first metal separator and a second metal separator) are laminated and integrated between a pair of end plates is disclosed in the following patent documents.

[0003] In this fuel cell stack, oxidant gas supply communication holes, oxidant gas discharge communication holes, fuel gas supply communication holes, and fuel gas discharge communication holes are opened in each separator and each MEA in the fuel cell. When oxidant gas is supplied to the first metal separator through each oxidant gas supply communication hole, the oxidant gas that has passed through the oxidant gas flow path of the first metal separator is discharged through each oxidant gas discharge communication hole, and fuel gas is supplied to the second metal separator through each fuel gas supply communication hole, and the fuel gas that has passed through the fuel gas flow path of the second metal separator is discharged through each fuel gas discharge communication hole. In this fuel cell, cooling medium supply communication holes and cooling medium discharge communication holes are opened in each separator and each MEA, and a configuration in which cooling medium is supplied to a cooling medium flow path formed on the joint surface of both separators is adopted, but the description of the configuration related to the cooling medium is omitted.

[0004] In this case, in this type of fuel cell stack, water is generated on the cathode side due to the reaction of both reaction gases during power generation. This water may also back-diffuse towards the anode electrode. When water accumulates in the reaction gas flow path, the flow of the reaction gas is obstructed, leading to a decrease in power generation capacity due to insufficient supply of reaction gas. Therefore, in this fuel cell stack, the first metal separator is configured such that the midpoint between the upper and lower oxidant gas discharge ports is located below the center in the direction of gravity in the oxidant gas flow path, and the second metal separator is configured such that the midpoint between the upper and lower fuel gas discharge ports is located below the center in the direction of gravity in the fuel gas flow path. Compared to a configuration where the midpoints of both discharge ports are at the same height as the center of the flow path, this makes it possible to smoothly discharge water in the flow path to the lower discharge port, thus avoiding a decrease in power generation capacity caused by water accumulation. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-121562 (pp. 5-16, Figures 1-10) [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the fuel cell stack disclosed in the above-mentioned patent document has the following problems that need to be solved. Specifically, in the above-mentioned fuel cell stack, the two separators are configured such that the midpoint located in the center of the upper discharge port and the lower discharge port is located below the center in the direction of gravity in the flow path of the reaction gas, thereby enabling the water in the flow path to be smoothly discharged to the lower discharge port. In other words, in the above-mentioned fuel cell stack, each separator is designed and manufactured based on the technical idea of ​​suppressing the accumulation of water in the flow path by making it easy for the generated water to move due to its own weight.

[0007] However, if at least a portion of the reaction gas flow path formed in the separator contains sections where the reaction gas needs to rise or move horizontally, water is likely to accumulate in those sections. This accumulated water hinders the movement of the reaction gas, resulting in a decrease in power generation efficiency. Furthermore, attempting to form the flow path without sections requiring the rise or horizontal movement of the reaction gas reduces the design flexibility regarding the shape of the power generation unit, potentially making circuit design difficult.

[0008] This invention has been made in view of the aforementioned problems to be solved, and its main objective is to provide a fuel cell unit that can suitably avoid a decrease in power generation capacity caused by the accumulation of water in the first gas flow path or the second gas flow path without reducing the design freedom of the power generation section. [Means for solving the problem]

[0009] To achieve the above objective, the fuel cell unit according to claim 1 comprises a power generation unit formed by stacking and integrating a plurality of flat plate-shaped laminates, each including at least a first separator constituting a first gas flow path for passing a first gas containing an oxidant, a second separator constituting a second gas flow path for passing a second gas containing hydrogen, and a membrane electrode assembly, wherein the fuel cell unit is configured to generate electricity by reacting the first gas, which is moved through the first gas flow path from a first air intake port in the first separator toward a first exhaust port in the first separator, and the second gas, which is moved through the second gas flow path from a second air intake port in the second separator toward a second exhaust port in the second separator, via the membrane electrode assembly, and further comprising a suction pump for drawing in the first gas from the first exhaust port, A first pipe connecting the first air intake port and the second air intake port, and a second pipe connecting the first exhaust port and the second exhaust port, Inflow of the first gas into the first air intake 、 Exhaust of the first gas from the first exhaust port. , the inflow of the second gas into the second air intake port, the exhaust of the second gas from the second exhaust port, the inflow of the first and second gases into the first and second piping, and the inflow of the first and second gases into the suction pump. It comprises a valve mechanism capable of allowing / regulating and a control unit that controls the operation of the suction pump and the valve mechanism, The valve mechanism has a first switching state in which the first gas flows into the first air inlet and the second gas flows into the second air inlet while restricting the inflow of the first gas and the second gas into the first and second pipes, and a second switching state in which the inflow of the first gas and the second gas into the suction pump is restricted, and the inflow of the first gas and the second gas into the first and second pipes, and the The device is configured to be switchable between a third switching state in which the inflow of the second gas into the second air inlet is restricted while the first gas is allowed to flow into the first air inlet, and a fourth switching state in which the inflow of the first gas into the first air inlet and the inflow of the second gas into the second air inlet is restricted while the inflow of the first gas into the first piping, the inflow of the first gas into the second air inlet, and the inflow of the first gas into the second piping are permitted.The control unit controls the valve mechanism when generating electricity in the power generation unit. The system is switched to the first switching state, thereby restricting the inflow of the first gas and the second gas into the first and second pipes, To the world's No. 1 air intake The Inflow of the first gas 、 Exhaust of the first gas from the first exhaust port, The inflow of the second gas into the second air intake port and the exhaust of the second gas from the second exhaust port. The suction pump is operated while allowing this to happen. Se, Yo When the first specified condition is met, the operation of the suction pump is continued while the valve mechanism is controlled. The system then transitions to the second switching state described above. Restricting at least one of the inflow of the first gas into the first air intake and the exhaust of the first gas from the first exhaust port. In addition, the inflow of the first gas and the second gas into the suction pump is restricted. Subsequently, when the second predetermined condition is met, the valve mechanism is controlled The system is switched to the third switching state, thereby restricting the inflow of the first gas and the second gas into the first and second piping, and the inflow of the second gas into the second air inlet, Allow the inflow of the first gas into the first air intake port and the exhaust of the first gas from the first exhaust port. When the predetermined third condition is met, the valve mechanism is controlled to switch to the second switching state while continuing the operation of the suction pump, thereby restricting the inflow of the first gas and the second gas into the suction pump; and thereafter, when the predetermined fourth condition is met, the valve mechanism is controlled to switch to the fourth switching state, thereby restricting the inflow of the first gas into the first air inlet and the inflow of the second gas into the second air inlet, while allowing the inflow of the first gas into the first piping, the inflow of the first gas into the second air inlet, and the inflow of the first gas into the second piping. .

[0011] Claim 2 The fuel cell unit described is, 1st article In the fuel cell unit, the control unit determines that the first condition is met when power generation in the power generation unit is completed.

[0012] Claim 3 The fuel cell unit described is, 1 In the fuel cell unit described above, the control unit determines that the third condition is met when power generation in the power generation unit is completed.

[0013] Claim 4 The fuel cell unit described is, 1st article The fuel cell unit includes a first pressure difference detection unit that detects the pressure difference occurring at the first air intake port and the first exhaust port, and the control unit determines that the first condition is met when the pressure difference detected by the first pressure difference detection unit exceeds a predetermined first upper limit value.

[0014] Claim 5 The fuel cell unit described is, 1In the fuel cell unit described, a second pressure difference detection unit that detects a pressure difference generated at the second air supply port and the second exhaust port is provided, and when the pressure difference detected by the second pressure difference detection unit exceeds a preset second upper limit value, the control unit determines that the third condition is satisfied.

[0015] Claim 6 The fuel cell unit described in claim 1st article In the fuel cell unit described, when the power generation efficiency in the power generation unit falls below a preset state, the control unit determines that the first condition is satisfied.

[0016] Claim 7 The fuel cell unit described in claim 1 In the fuel cell unit described, when the power generation efficiency in the power generation unit falls below a preset state, the control unit determines that the third condition is satisfied.

Advantages of the Invention

[0017] In the fuel cell unit according to claim 1, when the control unit performs power generation in the power generation unit, it controls the valve mechanism to allow the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port in the first separator, and operates the suction pump in a state where the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port are allowed. When a preset first condition is satisfied, while continuing the operation of the suction pump, the valve mechanism is controlled to regulate at least one of the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port. Then, when a preset second condition is satisfied, the valve mechanism is controlled to allow the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port.

[0018] Therefore, according to the fuel cell unit described in claim 1, when the first condition is satisfied and the operation of the suction pump is continued while restricting at least one of the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port, the negative pressure between the suction pump and the first air supply port or between the suction pump and the first exhaust port is increased. When the second condition is satisfied in this state and the inflow of the first gas into the first air supply port and the exhaust of the first gas from the first exhaust port are permitted, the first gas in the first gas flow path is rapidly exhausted from the first exhaust port. Along with this, the water staying in the first gas flow path can be drained from the first exhaust port. Thereby, even in the first gas flow path where it is difficult for water to move toward the first exhaust port by its own weight, the staying water can be surely drained. Therefore, it is possible to suitably avoid a decrease in the power generation ability caused by the retention of water in the first gas flow path without causing a decrease in the degree of freedom in the design related to the first separator.

[0019] Also, claim 1In the fuel cell unit described, when the power generation unit generates electricity, the control unit controls the valve mechanism to restrict the inflow of the first and second gases into the first and second pipes, while allowing the first gas to flow into the first air inlet and the second gas to flow into the second air inlet of the second separator, and when the first condition is met, the control unit controls the valve mechanism to restrict the inflow of the first and second gases to the suction pump, and thereafter, when the second condition is met, the control unit controls the valve mechanism to restrict the inflow of the first and second gases into the first and second pipes. Furthermore, the system transitions to a third switching state in which the first gas flows into the first air inlet while restricting the inflow of the second gas into the second air inlet, and when the predetermined third condition is met, the valve mechanism is controlled while continuing the operation of the suction pump to transition to the second switching state described above, and thereafter, when the predetermined fourth condition is met, the valve mechanism is controlled to transition to a fourth switching state in which the inflow of the first gas into the first air inlet and the inflow of the second gas into the second air inlet is restricted, while allowing the inflow of the first gas into the first piping, the inflow of the first gas into the second air inlet, and the inflow of the first gas into the second piping.

[0020] Therefore, Claim 1 According to the fuel cell unit described, when the first condition is met, the water in the first gas flow path is suitably drained. Furthermore, when the third condition is met, the operation of the suction pump is continued, and the system transitions to the second switching state, increasing the negative pressure between the suction pump and the first exhaust port. In this state, when the fourth condition is met, the system transitions to the fourth switching state, causing the second gas in the second gas flow path to be rapidly exhausted from the second exhaust port. Consequently, any water that had accumulated in the second gas flow path is drained from the second exhaust port. This ensures that even in a second gas flow path where water is difficult to move towards the second exhaust port due to its own weight, the accumulated water can be reliably drained. Therefore, a reduction in power generation capacity caused by water accumulation in the second gas flow path can be suitably avoided without reducing the design flexibility of the second separator.

[0021] Furthermore, claims 2 In the fuel cell unit described, the control unit determines that the first condition is met when power generation in the power generation unit has finished. 3 In the fuel cell unit described, the control unit determines that the third condition is met when power generation in the power generation unit has finished. Therefore, the claim 2,3 According to the fuel cell unit described, even if water accumulates in the first or second gas flow path during power generation, this water is reliably drained when power generation ends. Therefore, when power generation starts again, the passage of the first gas through the first gas flow path is not obstructed, nor is the passage of the second gas through the second gas flow path obstructed, allowing power generation to start smoothly.

[0022] Furthermore, claims 4 In the fuel cell unit described, the control unit determines that the first condition is met when the pressure difference detected by the first pressure difference detection unit, which detects the pressure difference occurring at the first air intake port and the first exhaust port, exceeds a predetermined first upper limit. 5 In the fuel cell unit described above, the control unit determines that the third condition is met when the pressure difference detected by the second pressure difference detection unit, which detects the pressure difference occurring at the second air intake and the second exhaust port, exceeds a predetermined second upper limit.

[0023] Therefore, Claim 4,5 According to the fuel cell unit described, when a large amount of water remains in the first gas flow path and the resistance of the first gas to passing through the first gas flow path increases, the detected pressure difference exceeds the first upper limit and the first condition is met, so the water in the first gas flow path is suitably drained. Similarly, when a large amount of water remains in the second gas flow path and the resistance of the second gas to passing through the second gas flow path increases, the detected pressure difference exceeds the second upper limit and the third condition is met, so the water in the second gas flow path is suitably drained. Thus, a sufficient amount of the first gas and the second gas required for suitable power generation can be reliably reacted.

[0024] Furthermore, claims 6 In the fuel cell unit described, the control unit determines that the first condition is met when the power generation efficiency in the power generation unit falls below a predetermined state. 7 In the fuel cell unit described, the control unit determines that the third condition is met when the power generation efficiency in the power generation unit falls below a predetermined state.

[0025] Therefore, Claim 6,7 According to the fuel cell unit described, when a large amount of water accumulates in the first gas flow path, increasing the resistance to the passage of the first gas and making it difficult to supply a sufficient amount of the first gas to the first separator, thus reducing the power generation capacity, the first condition is met and the water is drained from the first gas flow path. When a large amount of water accumulates in the second gas flow path, increasing the resistance to the passage of the second gas and making it difficult to supply a sufficient amount of the second gas to the second separator, thus reducing the power generation capacity, the third condition is met and the water is drained from the second gas flow path. Therefore, before the power generation capacity decreases further, the system can be restored to a state where it is possible to supply a sufficient amount of the first and second gases necessary for power generation, thereby enabling suitable power generation. [Brief explanation of the drawing]

[0026] [Figure 1] This diagram shows the configuration of fuel cell unit 1 and is an explanatory diagram for explaining the gas flow during power generation. [Figure 2] This is another diagram showing the configuration of the fuel cell unit 1, and is an explanatory diagram for describing the state immediately before transitioning to wastewater treatment of the air passage or hydrogen gas passage. [Figure 3] This is yet another diagram showing the configuration of fuel cell unit 1, and is an explanatory diagram for illustrating the state in which the air passage has transitioned to wastewater treatment. [Figure 4] This is yet another diagram showing the configuration of fuel cell unit 1, and is an explanatory diagram for illustrating the state when the hydrogen gas flow path has transitioned to wastewater treatment. [Modes for carrying out the invention]

[0027] The following describes an embodiment of the fuel cell unit with reference to the attached drawings.

[0028] The fuel cell unit 1 shown in Figures 1-4 is an example of a "fuel cell unit" and is configured to generate electricity by reacting gases for power generation (air (atmosphere: oxygen), which is an example of a "first gas containing an oxidizer," and hydrogen gas, which is an example of a "second gas containing hydrogen"). Specifically, the fuel cell unit 1 is composed of a pretreatment device 2, a suction pump 3, a supply source 4, a posttreatment device 5, piping 2-11, 4-12, 11-3, 12-5, 6a, 6b, switching valves 7a-7d, pressure sensors 8a-8d, a control unit 9, and a fuel cell cell 10.

[0029] In this case, the fuel cell cell 10 is an example of a "power generation unit formed by stacking and integrating multiple flat plate-shaped stacked objects," and includes a power generation stack consisting of a separator 11, which is an example of a "first separator," a separator 12, which is an example of a "second separator," and an MEA 13, which is an example of a "membrane electrode assembly (membrane electrode assembly for fuel cell)," as well as a separator (not shown) for passing a cooling fluid (air or coolant), and end plates (not shown) disposed at both ends in the stacking direction of each stacked object. In this example, each plate-shaped object, such as separators 11, 12, MEA 13, cooling separators, and end plates, corresponds to a "stacked object."

[0030] Furthermore, the separator 11 has grooves (not shown) for allowing air (atmosphere) to pass through, and the separator 12 has grooves (not shown) for allowing hydrogen gas to pass through. The MEA 13 is sandwiched between the two separators 11 and 12 and stacked together, so that the grooves of the separator 11 and one surface of the MEA 13 form an air passage 11a (an example of a "first gas passage"), and the grooves of the separator 12 and the other surface of the MEA 13 form a hydrogen passage 12a (an example of a "second gas passage"). The MEA 13 is also composed of an electrolyte membrane, a catalyst layer, and a gas diffusion layer.

[0031] In reality, a fuel cell cell 10 is configured with multiple power generation stacks and cooling separators depending on the power generation capacity required for the fuel cell unit 1. However, to facilitate understanding of the configuration and operation of the fuel cell unit 1, only one power generation stack is shown in the diagram, and the diagrams and explanations of the cooling separators and end plates are omitted.

[0032] On the other hand, the pretreatment device 2 is equipped with a filter and the like that removes foreign matter from the air (atmosphere) supplied to the fuel cell cell 10 (separator 11) and purifies it. However, the pretreatment device 2 may be unnecessary when the supplied air does not contain foreign matter to be removed, or when various industrial gases containing an oxidizer are used instead of air (atmosphere). The suction pump 3 is an example of a "suction pump" and, in accordance with the control of the control unit 9, sucks air from the air passage 11a through the exhaust port 11c (an example of a "first exhaust port") of the separator 11, thereby supplying new air treated by the pretreatment device 2 into the air passage 11a through the air inlet 11b (an example of a "first air inlet").

[0033] The supply source 4 consists of a hydrogen tank capable of storing hydrogen produced elsewhere, a conversion device for vaporizing liquefied hydrogen produced elsewhere, and a hydrogen gas generator capable of generating hydrogen gas, and is configured to supply hydrogen gas to the fuel cell cell 10 (separator 12). In this example, the fuel cell unit 1 employs a configuration in which the hydrogen gas supplied from the supply source 4 to the fuel cell cell 10 is humidified in the supply source 4 so that the humidity of the hydrogen gas is within a suitable humidity range.

[0034] The aftertreatment device 5 is a recovery device that removes (recovers) hydrogen contained in the gas (exhaust gas containing unreacted hydrogen in the fuel cell cell 10) supplied from the air intake port 12b (an example of a "second air intake port") of the separator 12 to the hydrogen flow path 12a and exhausted from the exhaust port 12c (an example of a "second exhaust port"), and exhaust port 12c Mix air (atmosphere) with the exhaust gas so that the hydrogen concentration of the exhaust gas falls below a predetermined value (exhaust port). 12c It consists of a mixing device (which dilutes the exhaust gas), etc. However, this post-treatment device 5 may be unnecessary when the hydrogen concentration of the exhaust gas is sufficiently low.

[0035] Piping 2-11 is connected to the pretreatment device 2 and the fuel cell cell 10 (separator 11) so that air can be supplied from the pretreatment device 2 to the air inlet 11b. Piping 4-12 is connected to the supply source 4 and the fuel cell cell 10 (separator 12) so that hydrogen gas can be supplied from the supply source 4 to the air inlet 12b. Piping 11-3 is connected to the suction pump 3 and the fuel cell cell 10 (separator 11) so that air can be drawn from the exhaust port 11c to the suction pump 3. Piping 12-5 is connected to the aftertreatment device 5 and the fuel cell cell 10 (separator 12) so that exhaust gas can be guided from the exhaust port 12c to the aftertreatment device 5. Piping 6a is an example of "the first piping that connects the first air inlet and the second air inlet", with one end connected to piping 2-11 and the other end connected to piping 4-12. Piping 6b is an example of "a second pipe connecting the first exhaust port and the second exhaust port," with one end connected to piping 12-5 and the other end connected to piping 11-3.

[0036] The switching valve 7a is located at the connection point between the above-mentioned pipe 2-11 and pipe 6a, and, according to the control of the control unit 9, allows / restricts the inflow of air into the air intake port 11b and the inflow of air into pipe 6a. The switching valve 7b is located at the connection point between the above-mentioned pipe 11-3 and pipe 6b, and, according to the control of the control unit 9, allows / restricts the suction of air from the exhaust port 11c to the suction pump 3 and the suction of air from pipe 6b to the suction pump 3. The switching valve 7c is located at the connection point between the above-mentioned pipe 4-12 and pipe 6a, and, according to the control of the control unit 9, allows / restricts the inflow of hydrogen gas from the supply source 4 to the air intake port 12b and pipe 6a, and the inflow of air from pipe 6a to the supply source 4 and the air intake port 12b. The switching valve 7d is located at the connection point between the piping 12-5 and piping 6b, and, in accordance with the control of the control unit 9, allows / regulates the inflow of hydrogen gas from the exhaust port 12c to the aftertreatment device 5, and the inflow of air, etc., from the exhaust port 12c to piping 6b.

[0037] In this example, the fuel cell unit 1 is composed of the above-mentioned switching valves 7a to 7d, forming a "valve mechanism." In Figures 1 to 4, the ports of the switching valves 7a to 7d that are blocked by the control unit 9 are shown in black. The switching control of each switching valve 7a to 7d by the control unit 9 will be explained in detail later.

[0038] The pressure sensors 8a and 8b, in conjunction with the control unit 9, constitute a "first pressure difference detection unit that detects the pressure difference occurring at the first air intake port and the first exhaust port." Pressure sensor 8a detects the pressure between the switching valve 7a and the air intake port 11b in the piping 2-11 (i.e., the pressure at the air intake port 11b), and pressure sensor 8b detects the pressure between the exhaust port 11c and the switching valve 7b in the piping 11-3 (i.e., the pressure at the exhaust port 11c). The control unit 9 then determines the pressure difference based on the pressures detected by both pressure sensors 8a and 8b. Alternatively, instead of pressure sensors 8a and 8b, a configuration can be adopted in which the pressure difference between the air intake port 11b and the exhaust port 11c is directly detected by a single differential pressure sensor (not shown).

[0039] The pressure sensors 8c and 8d, in conjunction with the control unit 9, constitute a "second pressure difference detection unit that detects the pressure difference occurring at the second air intake and the second exhaust port." Pressure sensor 8c detects the pressure between the switching valve 7c and the air intake port 12b in the piping 4-12 (i.e., the pressure at the air intake port 12b), and pressure sensor 8d detects the pressure between the exhaust port 12c and the switching valve 7d in the piping 12-5 (i.e., the pressure at the exhaust port 12c). The control unit 9 then determines the pressure difference based on the pressures detected by both pressure sensors 8c and 8d. Alternatively, instead of pressure sensors 8c and 8d, a configuration can be adopted in which the pressure difference between the air intake port 12b and the exhaust port 12c is directly detected by a single differential pressure sensor (not shown).

[0040] The control unit 9 provides overall control over the fuel cell unit 1. Specifically, the control unit 9 controls the suction pump 3 to draw in air and the supply source 4 to supply hydrogen gas. The control unit 9 also controls the flow of air and hydrogen gas by switching the switching valves 7a to 7d according to the operating state of the fuel cell unit 1 and the pressure detected by the pressure sensors 8a to 8d.

[0041] This fuel cell unit 1 is configured to operate in a "normal operation mode" that generates electricity by reacting air (oxygen) and hydrogen, as well as an "air channel drainage operation mode" that forcibly drains water generated in the air channel 11a from the fuel cell cell 10 (separator 11), and a "hydrogen channel drainage operation mode" that forcibly drains water generated in the hydrogen channel 12a from the fuel cell cell 10 (separator 12).

[0042] First, when generating power in the fuel cell cell 10 in "normal operation mode," the control unit 9 controls the suction pump 3 to start drawing in air and controls the supply source 4 to start supplying hydrogen gas. In this case, as shown in Figure 1, the control unit 9 controls the switching valve 7a to restrict the inflow of air from pipe 2-11 to pipe 6a while allowing the inflow of air from pipe 2-11 to the air inlet 11b, and controls the switching valve 7c to restrict the inflow of hydrogen gas from pipe 4-12 to pipe 6a while allowing the inflow of hydrogen gas from pipe 4-12 to the air inlet 12b, and controls the switching valve 7d to restrict the inflow of hydrogen gas from pipe 12-5 to pipe 6b while allowing the inflow of hydrogen gas from pipe 12-5 to the aftertreatment device 5, and controls the switching valve 7b to restrict the inflow of hydrogen gas from pipe 6b to pipe 11-3 while allowing the suction of air from pipe 11-3 to the suction pump 3 (an example of "a state in which the inflow of the first gas to the first air inlet and the exhaust of the first gas from the first exhaust port are permitted" and "a first switching state").

[0043] As a result, the air purified in the pretreatment device 2 is supplied to the air inlet 11b of the fuel cell cell 10 (separator 11) via piping 2-11, passes through the air passage 11a from the air inlet 11b towards the exhaust port 11c, and is then drawn from the exhaust port 11c to the suction pump 3 via piping 11-3. In addition, the hydrogen gas humidified in the supply source 4 is supplied to the air inlet 12b of the fuel cell cell 10 (separator 12) via piping 4-12, passes through the hydrogen passage 12a from the air inlet 12b towards the exhaust port 12c, and then flows from the exhaust port 12c to the aftertreatment device 5 via piping 12-5. As a result, electricity is generated in the fuel cell cell 10 by the reaction of air (oxygen) and hydrogen via the MEA 13.

[0044] In this case, when power generation is taking place in the fuel cell 10, water is generated on the cathode electrode side of the MEA 13 due to the reaction between oxygen and hydrogen. Furthermore, in this example, where humidified hydrogen gas from the supply source 4 is supplied to the fuel cell 10 (separator 12) for the purpose of improving power generation efficiency, the temperature of the hydrogen gas decreases due to heat exchange with the fuel cell 10 (separator 12), which is at a low temperature (room temperature) immediately after operation starts, and heat exchange with the air passing through the air channel 11a and the refrigerant passing through the cooling separator. As a result, moisture in the hydrogen gas condenses in the hydrogen channel 12a, and water may also be generated in the hydrogen channel 12a. Moreover, as described in the aforementioned patent document, water generated on the cathode electrode side may reverse diffuse to the anode electrode side (into the hydrogen channel 12a) (permeating through the MEA 13 and entering the hydrogen channel 12a), or water generated on the anode electrode side may reverse diffuse to the cathode electrode side (into the air channel 11a) (permeating through the MEA 13 and entering the air channel 11a).

[0045] Here, most of the water generated in the air channel 11a is moved through the air channel 11a along with the air passing through it and is drained out of the exhaust port 11c along with the exhaust, and most of the water generated in the hydrogen channel 12a is moved through the hydrogen channel 12a along with the hydrogen gas passing through it and is drained out of the exhaust port 12c along with the exhaust. However, for example, when the amount of air and hydrogen gas supplied to the fuel cell cell 10 per unit time is large and they are reacting favorably, the amount of water generated in the air channel 11a and hydrogen channel 12a increases, and some of the generated water may remain in the air channel 11a and hydrogen channel 12a. Therefore, when the supply of air and hydrogen gas is stopped in order to stop power generation in such a state, water will remain in the air channel 11a and hydrogen channel 12a.

[0046] On the other hand, when power generation by the fuel cell unit 1 is started, control is performed to gradually increase the supply of air and hydrogen gas to the fuel cell cell 10 until a state is reached in which oxygen and hydrogen can undergo a suitable reaction. In this case, if water was present in the air passage 11a or the hydrogen passage 12a at the end of the previous power generation, it is difficult to drain this water from the exhaust ports 11c and 12c because the amount of air and hydrogen gas supplied at the start of power generation is small. As a result, the passage of air is obstructed by the water in the air passage 11a, and the passage of hydrogen gas is obstructed by the water in the hydrogen passage 12a. Therefore, the time required to reach a state in which a suitable reaction can be obtained becomes longer.

[0047] Therefore, in the fuel cell unit 1 of this example, when power generation in "normal operation mode" ends, as an example, it operates in "air channel drainage operation mode" to drain the water in the air channel 11a, and then operates in "hydrogen channel drainage operation mode" to drain the water in the hydrogen channel 12a before stopping. Specifically, when the control unit 9 is instructed to end power generation by operation of an operation unit (not shown) or by a control signal from an external device (not shown), it first controls the supply source 4 to stop the supply of hydrogen gas to the fuel cell cell 10 while continuing the operation of the suction pump 3. As a result, the reaction between hydrogen and oxygen in the fuel cell cell 10 stops and power generation ends (an example of "when a predetermined first condition is met" and "when a predetermined third condition is met").

[0048] Next, the control unit 9 switches to the "airflow channel drainage operation mode". In this "airflow channel drainage operation mode", the control unit 9 continues to operate the suction pump 3 and, as shown in Figure 2, controls the switching valve 7a to restrict the inflow of air into the piping 6a and the air intake port 11b, and controls the switching valve 7b to restrict the inflow of air and hydrogen gas from the piping 6b to the piping 11-3, and the exhaust (inflow) of air from the exhaust port 11c to the piping 11-3. As a result, the inflow (suction) of air from the piping 11-3 to the suction pump 3 is restricted ("a state in which both the inflow of the first gas into the first air intake port and the exhaust of the first gas from the first exhaust port are restricted": an example of the "second switching state"). In this example, in the "second switching state" described above, the control unit 9 controls the switching valve 7c to restrict the inflow of hydrogen gas into the piping 6a and the hydrogen flow path 12a, and controls the switching valve 7d to restrict the exhaust of hydrogen gas from the hydrogen flow path 12a and the inflow of hydrogen gas, etc., into the piping 6b. As a result, the suction pump 3 is kept running, and the negative pressure between the suction pump 3 and the switching valve 7b in the piping 11-3 gradually increases (accumulation of negative pressure).

[0049] Next, when a predetermined amount of time has elapsed since switching each of the switching valves 7a to 7d to the "second switching state" (an example of when the "second condition" is met), the control unit 9 continues to operate the suction pump 3 and, as shown in Figure 3, controls switching valve 7a to restrict the inflow of air into piping 6a while allowing the inflow of air into the air intake port 11b, and controls switching valve 7b to restrict the inflow of air and hydrogen gas from piping 6b to piping 11-3 while allowing the exhaust (inflow) of air from exhaust port 11c to piping 11-3 (an example of the "third switching state"). In this example, in this "third switching state," the control unit 9 maintains the same state for switching valves 7c and 7d as in the "second switching state."

[0050] In this case, as described above, the suction pump 3 is allowed to continue operating after the switching valves 7a to 7d are switched to the "second switching state," causing the negative pressure between the suction pump 3 and the switching valve 7b in the piping 11-3 to rise. Therefore, when each of the switching valves 7a to 7d is switched to the "third switching state," the air between the switching valve 7b in the piping 11-3 and the separator 11 (exhaust port 11c) in the fuel cell cell 10 is rapidly drawn towards the suction pump 3. Consequently, the air in the air passage 11a is rapidly exhausted from the exhaust port 11c towards the piping 11-3, and the air in the piping 2-11 is rapidly drawn into the air passage 11a from the air intake port 11b. As a result, any water that had been stagnant in the air passage 11a is drained out of the exhaust port 11c along with the air, and the dry air newly drawn in from the air intake port 11b thoroughly dries the air passage 11a.

[0051] On the other hand, when a predetermined amount of time has elapsed since the switching valves 7a to 7d were switched to the "third switching state" as described above (when the time required for the drainage of water in the air passage 11a has elapsed), the control unit 9 switches to the "hydrogen passage drainage operation mode". Specifically, the control unit 9 continues to operate the suction pump 3 and switches the switching valves 7a to 7d back to the "second switching state". At this time, the negative pressure between the suction pump 3 and the switching valve 7b in the piping 11-3 gradually increases, similar to the operation in the "second switching state" before switching to the "third switching state".

[0052] Next, when a predetermined amount of time has elapsed since switching each of the switching valves 7a to 7d to the "second switching state" (an example of when the "fourth condition" is met), the control unit 9 continues to operate the suction pump 3 and, as shown in Figure 4, controls the switching valve 7a to restrict the inflow of air into the separator 11 (air inlet 11b) while allowing the inflow of air into the piping 6a, and controls the switching valve 7c to restrict the inflow (backflow) of air from the air supply source 4 that flows into the piping 4-12 via the piping 6a while allowing the inflow into the separator 12 (air inlet 12b). Furthermore, the control unit 9 controls the switching valve 7d to restrict the inflow of air that has passed through the separator 12 (hydrogen flow path 12a) and is exhausted from the exhaust port 12c to the aftertreatment device 5, while allowing its inflow into the piping 6b. It also controls the switching valve 7b to restrict the inflow (backflow) of air flowing into the piping 11-3 via the piping 6b to the separator 11 (exhaust port 11c), while allowing suction to the suction pump 3 (an example of the "fourth switching state").

[0053] In this case, as described above, the suction pump 3 is allowed to continue operating after the switching valves 7a to 7d are switched to the "second switching state," causing the negative pressure between the suction pump 3 and the switching valve 7b in the piping 11-3 to rise. Therefore, when each of the switching valves 7a to 7d is switched to the "fourth switching state," the gas in the piping 6b (such as air that flowed into the piping 6b when it was previously switched to the "fourth switching state") is rapidly drawn between the switching valve 7b and the suction pump 3 in the piping 11-3. Consequently, the gas in the piping 12-5 (hydrogen gas exhausted from the exhaust port 12c just before the end of power generation) is rapidly drawn into the piping 6b, the gas (hydrogen gas) in the hydrogen flow path 12a is rapidly exhausted from the exhaust port 12c towards the piping 12-5, and furthermore, the gas (hydrogen gas) in the piping 4-12 is rapidly drawn into the hydrogen flow path 12a from the air intake port 12b. Furthermore, the air in pipe 6a is rapidly drawn into pipe 4-12, and the air in pipe 2-11 is rapidly drawn into pipe 6a. As a result, the water that had been stagnant in the hydrogen flow path 12a is drained out of the exhaust port 12c along with the hydrogen gas, and the air that was drawn into pipe 4-12 via pipe 6a is drawn in from the air intake port 12b, and the inside of the hydrogen flow path 12a is thoroughly dried by this dry air.

[0054] After this, the control unit 9 terminates its operation in this "hydrogen channel drainage operation mode" when a predetermined time has elapsed since the switching valves 7a to 7d were switched to the "fourth switching state" (when the time required for the drainage of water in the hydrogen channel 12a has elapsed). Specifically, the control unit 9 stops the suction pump 3 and, as an example, switches each of the switching valves 7a to 7d back to the aforementioned "first switching state," thereby terminating the series of controls. As a result, the fuel cell unit 1 enters a stopped state (non-power generation state) when there is no water present in the air channel 11a and the hydrogen channel 12a.

[0055] Although an example has been described in which the system operates in "air channel drainage mode" to drain the air channel 11a and then operates in "hydrogen channel drainage mode" to drain the hydrogen channel 12a, it is also possible to operate in "hydrogen channel drainage mode" to drain the hydrogen channel 12a and then operate in "air channel drainage mode" to drain the air channel 11a. Furthermore, if necessary, drainage in "air channel drainage mode" (transition from "second switching state" to "third switching state") can be performed multiple times in a row, or drainage in "hydrogen channel drainage mode" (transition from "second switching state" to "fourth switching state") can be performed multiple times in a row. This allows for the efficient drainage of water in the air channel 11a and the hydrogen channel 12a without placing a high load on the suction pump 3 for an extended period in the "second switching state."

[0056] On the other hand, while we have described the process of draining water from the air channel 11a and the hydrogen channel 12a at the end of power generation (before stopping), depending on the operating state of the fuel cell unit 1, a large amount of water may be present in the air channel 11a or the hydrogen channel 12a even while power generation is in progress, making it difficult for air and hydrogen gas to pass through. In this state, the supply of air and / or hydrogen gas may be insufficient, preventing a favorable reaction and potentially making it difficult to generate the required amount of electricity. Therefore, the fuel cell unit 1 in this example is configured to allow draining of water from the air channel 11a and the hydrogen channel 12a as needed, even while operating in "normal operation mode" (when power generation is in progress).

[0057] For example, when a large amount of water accumulates in the air passage 11a during power generation, the resistance to air passage through the air passage 11a increases. As a result, the difference between the pressure on the exhaust port 11c side of the separator 11 (the negative pressure generated at the exhaust port 11c due to the suction of the suction pump 3) and the pressure on the intake port 11b side (the negative pressure extending to the intake port 11b via the air passage 11a) increases in proportion to the amount of water in the air passage 11a (the magnitude of the resistance to air passage).

[0058] Therefore, in the fuel cell unit 1 of this example, the control unit 9 determines that the "first condition" has been met when the difference between the pressure detected by the pressure sensor 8a installed in the piping 2-11 connected to the air intake port 11b (i.e., the negative pressure at the air intake port 11b) and the pressure detected by the pressure sensor 8b installed in the piping 11-3 connected to the exhaust port 11c (i.e., the negative pressure at the exhaust port 11c) exceeds a predetermined "first upper limit" (when the resistance of air passage through the air channel 11a becomes such that it may be difficult to pass the amount of air necessary for power generation), and operates in the aforementioned "air channel drainage operation mode" to drain the water in the air channel 11a, and then returns to the "normal operation mode". Note that the operation in the "air channel drainage operation mode" is the same as the operation in the "air channel drainage operation mode" at the end of power generation, so a redundant explanation will be omitted. As a result, the resistance of air passage through the air channel 11a becomes sufficiently small, making it possible to pass a sufficient amount of air necessary for power generation.

[0059] Furthermore, when a large amount of water accumulates in the hydrogen channel 12a during power generation, the resistance to hydrogen gas passage through the hydrogen channel 12a increases. As a result, the difference between the pressure on the exhaust port 12c side of the separator 12 (positive pressure generated at the exhaust port 11c) and the pressure on the intake port 12b side (positive pressure extending to the intake port 12b) increases in proportion to the amount of water in the hydrogen channel 12a (the magnitude of the passage resistance).

[0060] Therefore, in the fuel cell unit 1 of this example, when the difference between the pressure detected by the pressure sensor 8c installed in the piping 4-12 connected to the air intake port 12b (i.e., the positive pressure at the air intake port 12b) and the pressure detected by the pressure sensor 8d installed in the piping 12-5 connected to the exhaust port 12c (i.e., the positive pressure at the exhaust port 12c) exceeds a predetermined "second upper limit" (when the resistance of hydrogen gas passage through the hydrogen channel 12a becomes such that it may be difficult to pass the amount of hydrogen gas necessary for power generation), the control unit 9 considers that the "third condition" has been met and operates in the aforementioned "hydrogen channel drainage operation mode" to drain the water in the hydrogen channel 12a, and then returns to the "normal operation mode". Note that the operation in the "hydrogen channel drainage operation mode" is the same as the operation in the "hydrogen channel drainage operation mode" at the end of power generation, so redundant explanations are omitted. As a result, the resistance of hydrogen gas passage through the hydrogen channel 12a becomes sufficiently small, making it possible to pass a sufficient amount of hydrogen gas necessary for power generation.

[0061] Furthermore, as described above, when a large amount of water accumulates in the air channel 11a, increasing the resistance to air passage (i.e., when a sufficient amount of air necessary for the reaction is no longer supplied), or when a large amount of water accumulates in the hydrogen channel 12a, increasing the resistance to hydrogen gas passage (i.e., when a sufficient amount of hydrogen gas necessary for the reaction is no longer supplied), the power generation efficiency of the fuel cell cell 10 decreases. Therefore, in the fuel cell unit 1 of this example, when the power generation efficiency of the fuel cell cell 10 falls below a predetermined state during operation in "normal operation mode" (during power generation), as an example, the unit operates in "air channel drainage operation mode" to drain the water in the air channel 11a, and also operates in "hydrogen channel drainage operation mode" to drain the water in the hydrogen channel 12a, similar to the operation at the end of power generation described above. This ensures that a sufficient amount of air and hydrogen gas is supplied to the fuel cell cell 10, thereby increasing the power generation efficiency.

[0062] Furthermore, the phrase "when it falls below a predetermined state" refers, for example, to a situation where the actual amount of power generated per unit time falls below a predetermined percentage of the amount of power generated per unit time that would be expected from the amount of hydrogen gas supplied per unit time from the supply source 4 to the fuel cell cell 10 (separator 12) (such as the opening rate of a supply valve not shown in the supply source 4) or the amount of air drawn in per unit time from the fuel cell cell 10 (separator 11) by the suction pump 3 (such as the rotation speed of the suction pump 3).

[0063] Thus, in this fuel cell unit 1, when generating power in the fuel cell cell 10, the control unit 9 controls the valve mechanism (in this example, switching valves 7a to 7d) to allow air (atmosphere) to flow into the air intake port 11b of the separator 11 and air to be exhausted from the exhaust port 11c of the separator 11, and operates the suction pump 3 while allowing air to flow into the air intake port 11b and air to be exhausted from the exhaust port 11c of the separator 11. When the predetermined first condition is met, the control unit 9 continues to operate the suction pump 3 and controls the valve mechanism to restrict at least one (in this example, both) of the air to flow into the air intake port 11b and air to be exhausted from the exhaust port 11c. Subsequently, when the predetermined second condition is met, the control unit 9 controls the valve mechanism to allow air to flow into the air intake port 11b and air to be exhausted from the exhaust port 11c.

[0064] Therefore, with this fuel cell unit 1, when the "first condition" is met and the operation of the suction pump 3 continues, the inflow of air into the air intake port 11b and the exhaust of air from the exhaust port 11c are restricted, thereby increasing the negative pressure between the suction pump 3 and the exhaust port 11c. In this state, when the "second condition" is met and the inflow of air into the air intake port 11b and the exhaust of air from the exhaust port 11c are permitted, the air in the air passage 11a is rapidly exhausted from the exhaust port 11c, and as a result, the water that had been stagnant in the air passage 11a can be drained from the exhaust port 11c. This ensures that even in an air passage 11a where water is difficult to move toward the exhaust port 11c due to its own weight, the stagnant water can be reliably drained. Thus, a decrease in power generation capacity caused by water stagnation in the air passage 11a can be suitably avoided without reducing the design flexibility of the separator 11.

[0065] Furthermore, in this fuel cell unit 1, when the fuel cell cell 10 generates electricity, the control unit 9 controls the "valve mechanism" to restrict the inflow of air and hydrogen gas into the pipes 6a and 6b, while allowing air to flow into the air inlet 11b and hydrogen gas to flow into the air inlet 12b of the separator 12, transitioning to a "first switching state". When the "first condition" is met, the control unit 9 controls the "valve mechanism" to restrict the inflow of air and hydrogen gas to the suction pump 3, transitioning to a "second switching state". After the "second condition" is met, the control unit 9 controls the inflow of air and hydrogen gas into the pipes 6a and 6b. Furthermore, while restricting the inflow of hydrogen gas into the air inlet 12b, the system transitions to a "third switching state" in which air is introduced into the air inlet 11b. When the predetermined "third condition" is met, the operation of the suction pump 3 is continued, and the "valve mechanism" is controlled to transition to the "second switching state" described above. Subsequently, when the predetermined "fourth condition" is met, the "valve mechanism" is controlled to restrict the inflow of air into the air inlet 11b and the inflow of hydrogen gas into the air inlet 12b, while allowing the inflow of air into the piping 6a, the inflow of air into the air inlet 12b, and the inflow of air into the piping 6b.

[0066] Therefore, with this fuel cell unit 1, not only is the water in the air channel 11a suitably drained when the "first condition" is met, but when the "third condition" is met, the operation of the suction pump 3 is continued and the unit is moved to the "second switching state," increasing the negative pressure between the suction pump 3 and the exhaust port 11c. In this state, when the "fourth condition" is met and the unit is moved to the "fourth switching state," hydrogen gas etc. in the hydrogen channel 12a is rapidly exhausted from the exhaust port 12c, and consequently, the water that had been stagnant in the hydrogen channel 12a is drained from the exhaust port 12c. As a result, even in the hydrogen channel 12a where water is difficult to move toward the exhaust port 12c due to its own weight, the stagnant water can be reliably drained, thus suitably avoiding a decrease in power generation capacity caused by water stagnation in the hydrogen channel 12a without reducing the design flexibility of the separator 12.

[0067] Furthermore, in this fuel cell unit 1, the control unit 9 determines that the "first condition" and the "third condition" have been met when power generation in the fuel cell cell 10 has finished. Therefore, with this fuel cell unit 1, even if water accumulates in the air passage 11a or the hydrogen passage 12a during power generation, this water is reliably drained when power generation ends. As a result, when power generation starts again, the passage of air through the air passage 11a is not obstructed, and the passage of hydrogen gas through the hydrogen passage 12a is not obstructed, allowing power generation to start smoothly.

[0068] Furthermore, in this fuel cell unit 1, the control unit 9 determines that the "first condition" is met when the pressure difference detected by pressure sensors 8a and 8b, which detect the pressure difference occurring at the air intake port 11b and the exhaust port 11c, exceeds a predetermined "first upper limit". Also, in this fuel cell unit 1, the control unit 9 determines that the "third condition" is met when the pressure difference detected by pressure sensors 8c and 8d, which detect the pressure difference occurring at the air intake port 12b and the exhaust port 12c, exceeds a predetermined "second upper limit".

[0069] Therefore, with this fuel cell unit 1, when a large amount of water remains in the air channel 11a and the resistance to air passage through the air channel 11a increases, the detected "pressure difference" exceeds the "first upper limit" and the "first condition" is met, so the water in the air channel 11a is suitably drained. Similarly, when a large amount of water remains in the hydrogen channel 12a and the resistance to hydrogen gas passage through the hydrogen channel 12a increases, the detected "pressure difference" exceeds the "second upper limit" and the "third condition" is met, so the water in the hydrogen channel 12a is suitably drained. Thus, a sufficient amount of air and hydrogen gas necessary for suitable power generation can be reliably reacted.

[0070] Furthermore, in this fuel cell unit 1, the control unit 9 determines that the "first condition" is met when the power generation efficiency of the fuel cell cell 10 falls below a "pre-defined power generation efficiency". Also, in this fuel cell unit 1, the control unit 9 determines that the "third condition" is met when the power generation efficiency of the fuel cell cell 10 falls below a "pre-defined power generation efficiency".

[0071] Therefore, with this fuel cell unit 1, when a large amount of water accumulates in the air passage 11a, increasing the resistance to air passage and making it difficult to supply a sufficient amount of air to the separator 11, thus reducing the power generation capacity, the "first condition" is met and the water is drained from the air passage 11a. Similarly, when a large amount of water accumulates in the hydrogen passage 12a, increasing the resistance to hydrogen gas passage and making it difficult to supply a sufficient amount of hydrogen gas to the separator 12, thus reducing the power generation capacity, the "third condition" is met and the water is drained from the hydrogen passage 12a. Thus, before the power generation capacity decreases further, the system can be restored to a state where a sufficient amount of air and hydrogen gas necessary for power generation can be supplied, allowing for efficient power generation.

[0072] The configuration of the "fuel cell unit" is not limited to the example of the configuration of fuel cell unit 1 described above.

[0073] For example, the explanation described a configuration in which the control unit 9 determines that the "second condition" has been met when a "pre-defined time" has elapsed after switching each of the switching valves 7a to 7d to the "second switching state." However, instead of such a configuration (or in addition to such a configuration), a configuration can also be adopted in which the "second condition" is determined to be met when the pressure (negative pressure) between the suction pump 3 and the switching valve 7b in the piping 11-3 reaches a pre-defined pressure, or when the load applied to the suction pump 3 reaches a pre-defined load amount (when the operating current of the suction pump 3 reaches a specified current value).

[0074] Furthermore, while the explanation described an example in which the suction pump 3 is kept running in the "second switching state" to increase the negative pressure between the suction pump 3 and the switching valve 7b in the piping 11-3 (accumulating negative pressure), by connecting a sealed pressure-resistant container (buffer tank: not shown) between the suction pump 3 and the switching valve 7b in the piping 11-3, it becomes possible to accumulate sufficient negative pressure in the "second switching state". By adopting such a configuration, when switching to the "third switching state" or the "fourth switching state", it becomes possible to draw a large amount of air into the sealed pressure-resistant container which is under negative pressure, and move a sufficient amount of air at high speed, thereby ensuring reliable drainage.

[0075] Furthermore, although the explanation described an example of a fuel cell unit 1 configured to allow drainage from both the air channel 11a and the hydrogen channel 12a, it is also possible to adopt a configuration that allows drainage only from the air channel 11a (a configuration that does not allow drainage from the hydrogen channel 12a).

[0076] Specifically, as an example, by eliminating the piping 6a, 6b and switching valves 7a to 7d in the fuel cell unit 1 described above, and by installing an on-off valve as a "valve mechanism" in either piping 2-11 or 11-3, the on-off valve can be opened to allow air to flow in from the air intake port 11b and exhaust from the exhaust port 11c, and closed to restrict air to flow in from the air intake port 11b and exhaust from the exhaust port 11c. In this case, by providing an on-off valve in piping 2-11, the "inflow of the first gas into the first air intake port" can be restricted when the "first condition" is met, and by providing an on-off valve in piping 11-3, the "exhaust of the first gas from the first exhaust port" can be restricted when the "first condition" is met, thereby enabling efficient drainage from the air passage 11a.

[0077] Furthermore, although the configuration of the fuel cell unit 1 equipped with a hydrogen gas supply source 4 was explained as an example, it is also possible to create a "fuel cell unit" that does not have a supply source 4, but instead obtains hydrogen gas from an external "hydrogen gas supply source" to generate electricity. Also, although the configuration of the fuel cell unit 1 equipped with a post-treatment device 5 that processes exhaust gas containing unreacted hydrogen was explained as an example, it is also possible to omit the post-treatment device 5 and instead have various external treatment devices process the exhaust gas from the fuel cell cell 10 (separator 12). [Explanation of symbols]

[0078] 1 Fuel cell unit 2 Pre-treatment device 3. Suction pump 4 Source 5. Post-processing equipment 2-11, 4-12, 11-3, 12-5, 6a, 6b Piping 7a~7d Switching valve 8a~8d Pressure Sensor 9. Control Unit 10 fuel cell cells 11,12 Separator 11a Airflow channel 11b,12b Air supply port 11c, 12c exhaust port 12 Separators 12a Hydrogen channel 13 MEA

Claims

1. A fuel cell unit comprising a power generation unit formed by stacking and integrating a plurality of flat plate-shaped laminates, each including at least a first separator constituting a first gas flow path for passing a first gas containing an oxidizing agent, a second separator constituting a second gas flow path for passing a second gas containing hydrogen, and a membrane electrode assembly, wherein the unit is configured to generate electricity by reacting the first gas, which is moved through the first gas flow path from a first air intake port in the first separator toward a first exhaust port in the first separator, with the second gas, which is moved through the second gas flow path from a second air intake port in the second separator toward a second exhaust port in the second separator, via the membrane electrode assembly, A suction pump for drawing the first gas from the first exhaust port, A first pipe connecting the first air intake port and the second air intake port, and a second pipe connecting the first exhaust port and the second exhaust port, A valve mechanism capable of allowing / regulating the inflow of the first gas into the first air intake, the exhaust of the first gas from the first exhaust port, the inflow of the second gas into the second air intake, the exhaust of the second gas from the second exhaust port, the inflow of the first and second gases into the first and second piping, and the inflow of the first and second gases into the suction pump, The system comprises a control unit that controls the operation of the suction pump and the valve mechanism, The valve mechanism is A first switching state in which the inflow of the first gas and the second gas into the first and second piping is restricted, while the first gas is allowed to flow into the first air inlet and the second gas is allowed to flow into the second air inlet, A second switching state that restricts the inflow of the first gas and the second gas into the suction pump, A third switching state in which the inflow of the first gas and the second gas into the first and second piping, and the inflow of the second gas into the second air inlet are restricted, while the first gas is allowed to flow into the first air inlet, The system is configured to be switchable to a fourth switching state that restricts the inflow of the first gas into the first air inlet and the inflow of the second gas into the second air inlet, while allowing the inflow of the first gas into the first piping, the inflow of the first gas into the second air inlet, and the inflow of the first gas into the second piping. The control unit, When generating power in the power generation unit, the valve mechanism is controlled to switch to the first switching state, restricting the inflow of the first gas and the second gas into the first and second piping, while operating the suction pump in a state that allows the inflow of the first gas into the first air intake, the exhaust of the first gas from the first exhaust port, the inflow of the second gas into the second air intake, and the exhaust of the second gas from the second exhaust port. When the predetermined first condition is met, the valve mechanism is controlled to switch to the second switching state while continuing the operation of the suction pump, thereby restricting at least one of the inflow of the first gas into the first air intake and the exhaust of the first gas from the first exhaust port, and restricting the inflow of the first gas and the second gas into the suction pump, and thereafter when the predetermined second condition is met, the valve mechanism is controlled to switch to the third switching state, thereby restricting the inflow of the first gas and the second gas into the first and second piping, and the inflow of the second gas into the second air intake, while allowing the inflow of the first gas into the first air intake and the exhaust of the first gas from the first exhaust port. A fuel cell unit that, when a predetermined third condition is met, continues the operation of the suction pump while controlling the valve mechanism to transition to the second switching state, thereby restricting the inflow of the first gas and the second gas into the suction pump; and thereafter, when a predetermined fourth condition is met, controls the valve mechanism to transition to the fourth switching state, thereby restricting the inflow of the first gas into the first air inlet and the inflow of the second gas into the second air inlet, while allowing the inflow of the first gas into the first piping, the inflow of the first gas into the second air inlet, and the inflow of the first gas into the second piping.

2. The fuel cell unit according to claim 1, wherein the control unit determines that the first condition has been met when power generation in the power generation unit has finished.

3. The fuel cell unit according to claim 1, wherein the control unit determines that the third condition has been met when power generation in the power generation unit has finished.

4. It includes a first pressure difference detection unit that detects the pressure difference occurring at the first air intake port and the first exhaust port, The fuel cell unit according to claim 1, wherein the control unit determines that the first condition is met when the pressure difference detected by the first pressure difference detection unit exceeds a predetermined first upper limit.

5. The system includes a second pressure difference detection unit that detects the pressure difference occurring at the second air intake port and the second exhaust port, The fuel cell unit according to claim 1, wherein the control unit determines that the third condition is met when the pressure difference detected by the second pressure difference detection unit exceeds a predetermined second upper limit.

6. The fuel cell unit according to claim 1, wherein the control unit determines that the first condition is met when the power generation efficiency in the power generation unit falls below a predetermined state.

7. The fuel cell unit according to claim 1, wherein the control unit determines that the third condition is met when the power generation efficiency in the power generation unit falls below a predetermined state.

Images