Fuel cell system

Abstract

This fuel cell starts up quickly from low temperatures and begins generating electricity. [Solution] When the fuel cell stack 2 is in a low temperature state at startup to begin power generation, the fuel cell system 1 starts generating power in the power generation unit in the region between the one-end current collector plate 11 and the startup current collector plate 13 when the temperature of the region between the one-end current collector plate 11 and the startup current collector plate 13 reaches a temperature at which power generation is possible. Subsequently, when the temperature of the region between the one-end current collector plate 11 and the other-end current collector plate 12 reaches a temperature at which power generation is possible, the power generation unit in the region between the one-end current collector plate 11 and the other-end current collector plate 12 starts generating power. The fuel cell system 1 can start generating power before the entire fuel cell stack 2 reaches a temperature at which power generation is possible.

Description

Technical Field

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

Background Art

[0002] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The fuel cell system of the present invention comprises a fuel cell stack comprising a plurality of power generation units stacked on top of each other; a heater that heats the oxidizing gas and is positioned to be able to make thermal contact with the fuel cell stack; a plurality of current collectors that output the power generated by the fuel cell stack to the outside; power transmission members connected to the current collectors; a power extractor to which the power transmission members are connected; a power transmitter to which the power generated via the power extractor is transmitted; and a temperature detector that detects the temperature of the fuel cell stack.

[0008] The multiple current collector plates include one-end current collector plate attached to one end of the fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, another-end current collector plate attached to the other end of the fuel cell stack in the stacking direction of the power generation unit, and a starting current collector plate sandwiched between adjacent power generation units of the fuel cell stack in the stacking direction of the power generation unit.

[0009] The power extractor described above is capable of selectively combining multiple current collectors to transmit power to the power transmitter. When starting up the fuel cell stack to begin generating power, it selects either the starting current collector or the other end current collector based on the temperature of the fuel cell stack, and extracts the power generated by multiple power generation units located between the selected current collector and the one end current collector to the power transmitter. [Effects of the Invention]

[0010] The fuel cell system of the present invention can start generating electricity using multiple power generation units sandwiched between a heater-side current collector plate and a starting current collector plate, which have become capable of generating electricity due to the heat from the heater, before the entire fuel cell stack reaches a temperature at which it can generate electricity. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram illustrating the fuel cell system in the first embodiment of the present invention. [Figure 2]A schematic diagram illustrating a fuel cell system in a second embodiment of the present invention. [Figure 3] A schematic diagram illustrating a fuel cell system in a third embodiment of the present invention. [Figure 4] A schematic diagram illustrating various gas flow paths in a fuel cell system according to a third embodiment of the present invention. [Figure 5] A schematic diagram illustrating a fuel cell system according to a fourth embodiment of the present invention. [Figure 6] A schematic diagram illustrating the fuel cell system in the fifth embodiment of the present invention. [Figure 7] A schematic diagram illustrating the fuel cell system in the sixth embodiment of the present invention. [Figure 8] A schematic diagram illustrating a plan view of the fuel cell stack of the fuel cell system in the sixth embodiment of the present invention. [Figure 9] A schematic diagram illustrating the power transmission member of a fuel cell system in a sixth embodiment of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a schematic explanatory diagram showing a fuel cell system 1 in the first embodiment of the present invention.

[0013] The fuel cell system 1 is, for example, one installed in a vehicle such as an automobile, and generates electricity by supplying fuel gas and an oxidizer gas (for example, air).

[0014] The fuel cell system 1 in the first embodiment includes a fuel cell stack 2, a GPU (Gas Processing Unit) 3, a plurality of current collector plates 4, a power transmission member 5, a power extractor 6, a power transmission unit 7, a temperature sensor 8, an end plate 9, and a battery 10.

[0015] The fuel cell stack 2 is a cuboid-shaped solid oxide fuel cell stack (SOFC stack) formed by stacking a plurality of sheet-shaped power generation units (not shown). The fuel cell stack 2 stacks (lays) a plurality of power generation units, and in the stacking direction of the power generation units (the vertical direction in FIG. 1), an anode flow path (not shown) through which fuel gas flows and a cathode flow path (not shown) through which oxidant gas flows are alternately formed. The fuel cell stack 2 can generate electricity by supplying fuel gas and oxidant gas to these anode gas flow paths and cathode gas flow paths, respectively.

[0016] The GPU 3 corresponds to a heater and is constituted by integrating a combustor (not shown) that catalytically burns the fuel gas (anode off-gas) that has passed through the fuel cell stack 2 and a heat exchanger (not shown) that heats the oxidant gas supplied to the fuel cell stack 2 with the heat obtained by burning the fuel gas in the combustor.

[0017] The GPU 3 is arranged on one end side of the fuel cell stack 2 in the stacking direction of the power generation units so as to be in thermal contact with the fuel cell stack 2. More specifically, the GPU 3 is in contact with the one-end-side current collector plate 11 described later and is arranged so as to cover the end of the fuel cell stack 2 on one side in the stacking direction of the power generation units.

[0018] The current collector plate 4 is overlapped with the fuel cell stack 2 and outputs (extracts) the electric power generated by the fuel cell stack 2 to the outside, and is formed, for example, in a flat plate shape.

[0019] In the fuel cell system 1 of the first embodiment, the plurality of current collectors 4 include one end side current collector 11 attached to one end of the fuel cell stack 2 on the side where the GPU 3 of the fuel cell stack 2 is located in the stacking direction of the power generation units, the other end side current collector 12 attached to the other end of the fuel cell stack 2 in the stacking direction of the power generation units, and one starting current collector 13 sandwiched between adjacent power generation units of the fuel cell stack 2 in the stacking direction of the power generation units. The one end side current collector 11 is sandwiched and held between the GPU 3 and the fuel cell stack 2. The other end side current collector 12 is sandwiched and held between the end plate 9 and the fuel cell stack 2. The starting current collector 13 is disposed at a position shifted (closer) to one end side than the central position of the fuel cell stack 2 in the stacking direction of the power generation units.

[0020] The current collector 4 extracts the electric power generated by a plurality of power generation units between a pair of current collectors 4. For example, the one end side current collector 11 is the negative electrode, and the other end side current collector 12 and the starting current collector 13 are the positive electrodes. In the fuel cell system 1 of the first embodiment, power generation by a plurality of power generation units between the one end side current collector 11 and the starting current collector 13, or power generation by a plurality of power generation units between the one end side current collector 11 and the other end side current collector 12 is possible. That is, in the fuel cell system 1 of the first embodiment, prior to power generation by a plurality of power generation units between the one end side current collector 11 and the other end side current collector 12, which is power generation of the entire fuel cell stack 2, power generation by a plurality of power generation units between the one end side current collector 11 and the starting current collector 13 is possible.

[0021] The power transmission member 5 has one end connected to the current collector 4. In the fuel cell system 1 of the first embodiment, for example, it is a power cable.

[0022] The power extractor 6 is connected to the other end of the power transmission member 5 and selectively combines multiple current collectors to transmit power to the power transmitter 7. Specifically, the power extractor 6 combines one of the positive current collectors (the other end 12) and the starting current collector (the 13) with the negative current collector (the one end 11) to transmit the power generated by the fuel cell stack 2 to the power transmitter 7. The power extractor 6 is connected to the power transmitter 7 and, for example, is integrated with the power transmitter 7.

[0023] Here, when the fuel cell stack 2 starts generating power, if the fuel cell stack 2 is in a low-temperature state, the power extractor 6 selects either the starting current collector plate 13 or the other end current collector plate 12 based on the temperature of the fuel cell stack 2 detected by the temperature sensor 8, and extracts the power generated by the multiple power generation units located between the selected current collector plate and the one end current collector plate 11 to the power transmitter 7.

[0024] The power transmitter 7 receives the power generated via the power extractor 6. The power transmitted to the power transmitter 7 is then sent to the battery 10 for charging.

[0025] The temperature sensor 8 is equivalent to a temperature detector and is attached to the fuel cell stack 2, capable of detecting the temperature of the fuel cell stack 2. For example, the temperature sensor 8 detects the temperature of the oxidizer gas that has passed through the fuel cell stack 2.

[0026] The end plate 9 covers the other end of the fuel cell stack 2 that is away from the GPU3 in the stacking direction of the power generation unit. The end plate 9, together with the GPU3, sandwiches the fuel cell stack 2 in the stacking direction of the power generation unit and presses the fuel cell stack 2 in the stacking direction of the power generation unit. The end plate 9 is in contact with the current collector plate 12 on the other end.

[0027] In the fuel cell system 1 of the first embodiment, fuel gas is supplied to the GPU3 from the outside, heated in the GPU3 and then sent to the fuel cell stack 2, then flows from the fuel cell stack 2 to the GPU3, where it is mixed with oxidizer gas and burned before being discharged to the outside from the GPU3. Also in the fuel cell system 1 of the first embodiment, oxidizer gas is supplied to the GPU3 from the outside, heated in the GPU3 and then sent to the fuel cell stack 2, then flows from the fuel cell stack 2 to the GPU3, where it is mixed with fuel gas and burned before being discharged to the outside from the GPU3.

[0028] In the first embodiment of the fuel cell system 1, the fuel cell stack 2 is in thermal contact with the GPU 3. Specifically, the fuel cell stack 2 is connected in series with the GPU 3 along the stacking direction of the power generation units via a current collector plate 11 at one end. As a result, in the fuel cell system 1 of the first embodiment, the temperature of the power generation units close to the GPU 3 tends to rise due to heat transfer from the GPU 3.

[0029] In the first embodiment of the fuel cell system 1, when the fuel cell stack 2 is in a low-temperature state at startup to begin generating power, power generation begins in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13 when the temperature of the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13 reaches a temperature at which power generation is possible. Subsequently, when the temperature of the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12 reaches a temperature at which power generation is possible, the fuel cell system 1 of the first embodiment begins generating power in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12. When power is generated in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12, the startup current collector plate 13 is not used to extract the generated power.

[0030] In the first embodiment of the fuel cell system 1 described above, before the entire fuel cell stack 2 reaches a temperature at which it can generate electricity, power can be started by multiple power generation units sandwiched between the one-end current collector plate 11 and the starting current collector plate 13, which have become capable of generating electricity due to the heat from the GPU 3, and power can be supplied to the battery 10 via the power transmitter 7.

[0031] Therefore, the fuel cell system 1 of the first embodiment can selectively extract power from the power generation unit in the region where the heating rate of the fuel cell stack 2 is fast, making it possible to obtain reaction heat early and, overall, shorten the system startup time.

[0032] Furthermore, in the fuel cell system 1 of the first embodiment, since the starting current collector plate 13 is positioned offset to one end of the fuel cell stack 2 in the stacking direction of the power generation unit, power can be extracted from the fuel cell stack 2 more quickly compared to the case where the starting current collector plate 13 is located in the center of the fuel cell stack 2 in the stacking direction of the power generation unit.

[0033] Furthermore, the fuel cell system 1 of the first embodiment minimizes the number of starting current collector plates 13, thereby minimizing the heat dissipation path from the fuel cell stack 2. It also selectively extracts power from the power generation unit in the region with a fast heating rate even before the entire fuel cell stack 2 reaches a temperature at which it can start up (generate power), thus enabling early acquisition of reaction heat (heat generated by power generation).

[0034] Other embodiments of the present invention will be described below. Note that components identical to those in the embodiments described above are denoted by the same reference numerals, and redundant descriptions are omitted.

[0035] A second embodiment of the present invention will be described using Figure 2. The fuel cell system 21 of the second embodiment has substantially the same configuration as the fuel cell system 1 of the first embodiment described above, but as shown in Figure 2, the starting current collector plates 13 are arranged one by one at different positions in the stacking direction of the power generation units. The starting current collector plate 13a is located on one end side of the fuel cell stack 2 than the starting current collector plate 13b in the stacking direction of the power generation units. Figure 2 is a schematic explanatory diagram showing the fuel cell system 21 in the second embodiment of the present invention.

[0036] Then, when the fuel cell stack 2 starts generating power, if the fuel cell stack 2 is in a low-temperature state, the power extractor 6 selects one of either the other end current collector plate 12 or one of the multiple starting current collector plates 13 based on the temperature of the fuel cell stack 2 detected by the temperature sensor 8, and extracts the power generated by the multiple power generation units located between the selected current collector plate and the one end current collector plate 11 to the power transmitter 7. In other words, when the power extractor 6 selects one of either the other end current collector plate 12 or one of the multiple starting current collector plates 13, the higher the temperature of the fuel cell stack 2, the closer it is to the other end of the fuel cell stack 2.

[0037] In the fuel cell system 21 of this second embodiment, if the fuel cell stack 2 is in a low-temperature state when starting up to begin generating power in the fuel cell stack 2, the current collector plate paired with the current collector plate 11 at one end is switched so that as the temperature of the fuel cell stack 2 increases, power generation is performed using the current collector plate closer to the other end of the fuel cell stack 2.

[0038] In the fuel cell system 21 of the second embodiment, if the fuel cell stack 2 is in a low-temperature state at startup when power generation begins in the fuel cell stack 2, power generation begins in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13a when the temperature of the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13a reaches a temperature at which power generation can be achieved. Subsequently, when the temperature of the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13b reaches a temperature at which power generation can be achieved, the fuel cell system 21 of the second embodiment generates power in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13b. When power is generated in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the startup current collector plate 13b, the startup current collector plate 13a is not used to extract the generated power. Then, when the temperature of the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12 reaches a temperature at which power generation is possible, the fuel cell system 21 of the second embodiment starts generating power in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12. When power is generated in the power generation unit in the region sandwiched between the one-end current collector plate 11 and the other-end current collector plate 12, the starting current collector plates 13a and 13b are not used to extract the generated power.

[0039] In this second embodiment of the fuel cell system 21, substantially the same effects and advantages as those of the first embodiment of the fuel cell system 1 described above can be achieved.

[0040] Furthermore, the fuel cell system 21 of the second embodiment has multiple starting current collector plates 13, which increases the number of heat dissipation paths compared to the fuel cell system 1 of the first embodiment. However, having multiple starting current collector plates 13 allows for more efficient and selective extraction of power from the power generation unit in the region where the heating rate of the fuel cell stack 2 is fast.

[0041] A third embodiment of the present invention will be described using Figure 3. The fuel cell system 31 of the third embodiment has substantially the same configuration as the fuel cell system 1 of the first embodiment described above, but as shown in Figure 3, the fuel cell stack 2 consists of a first fuel cell stack 2a and a second fuel cell stack 2b. Figure 3 is a schematic explanatory diagram showing the fuel cell system 31 in the third embodiment of the present invention.

[0042] The GPU3 is positioned to allow thermal contact with the first fuel cell stack 2a and the second fuel cell stack 2b. The first fuel cell stack 2a and the second fuel cell stack 2b are positioned facing each other with the GPU3 in between. The first fuel cell stack 2a and the second fuel cell stack 2b are positioned so that one end of each can make thermal contact with the GPU3. Specifically, the first fuel cell stack 2a and the second fuel cell stack 2b are connected in series to the GPU3 along the stacking direction of the power generation unit via one-end current collector plates 11. Furthermore, the first fuel cell stack 2a and the second fuel cell stack 2b are positioned with the GPU3 in between and are arranged in series along the stacking direction of the power generation unit.

[0043] The first fuel cell stack 2a is equipped with a reforming catalyst (not shown) in its internal anode channel. The fuel gas supplied to the first fuel cell stack 2a is reformed within the first fuel cell stack 2a.

[0044] The second fuel cell stack 2b has a smaller heat capacity than the first fuel cell stack 2a. The second fuel cell stack 2b is supplied with fuel gas that has passed through the first fuel cell stack 2a.

[0045] Furthermore, in the third embodiment of the fuel cell system 31, the current collector plate 4 consists of a first current collector plate 4a and a second current collector plate 4b, the power transmission member 5 consists of a first power transmission member 5a and a second power transmission member 5b, the power extractor 6 consists of a first power extractor 6a and a second power extractor 6b, and the end plate 9 consists of a first end plate 9a and a second end plate 9b.

[0046] The first current collector plate 4a outputs the power generated by the first fuel cell stack 2a to the outside. The second current collector plate 4b outputs the power generated by the second fuel cell stack 2b to the outside.

[0047] The first current collector plate 4a consists of a one-end current collector plate 11, which is attached to one end of the first fuel cell stack 2a on the side where the GPU3 is located in the stacking direction of the power generation units; a other-end current collector plate 12, which is attached to the other end of the first fuel cell stack 2a in the stacking direction of the power generation units; and a single starting current collector plate 13, which is sandwiched between adjacent power generation units of the first fuel cell stack 2a in the stacking direction of the power generation units. The one-end current collector plate 11 of the first current collector plate 4a is sandwiched between the GPU3 and the first fuel cell stack 2a. The other-end current collector plate 12 of the first current collector plate 4a is sandwiched between the first end plate 9a and the first fuel cell stack 2a. The first end plate 9a covers the other end of the first fuel cell stack 2a that is away from the GPU3 in the stacking direction of the power generation units. The first end plate 9a, together with the GPU 3, sandwiches the first fuel cell stack 2a in the stacking direction of the power generation unit, and presses the first fuel cell stack 2a in the stacking direction of the power generation unit. The first end plate 9a is in contact with the other end current collector plate 12 of the first current collector plate 4a. The starting current collector plate 13 of the first current collector plate 4a is positioned at a location that is shifted (closer) to one end of the center position of the first fuel cell stack 2a in the stacking direction of the power generation unit.

[0048] The second current collector plate 4b consists of a one-end current collector plate 11, which is attached to one end of the second fuel cell stack 2b on the side where the GPU3 is located in the stacking direction of the power generation unit, and a other-end current collector plate 12, which is attached to the other end of the second fuel cell stack 2b in the stacking direction of the power generation unit. The one-end current collector plate 11 of the second current collector plate 4b is sandwiched and held between the GPU3 and the second fuel cell stack 2b. The other-end current collector plate 12 of the second current collector plate 4b is sandwiched and held between the second end plate 9b and the second fuel cell stack 2b. The second end plate 9b covers the other end of the second fuel cell stack 2b that is away from the GPU3 in the stacking direction of the power generation unit. The second end plate 9b, together with the GPU3, sandwiches the second fuel cell stack 2b in the stacking direction of the power generation unit and presses the second fuel cell stack 2b in the stacking direction of the power generation unit. The second end plate 9b is in contact with the other end current collector plate 12 of the second current collector plate 4b.

[0049] The first power transmission member 5a is connected to the first current collector plate 4a. The second power transmission member 5b is connected to the second current collector plate 4b.

[0050] The first power extractor 6a is connected to the first power transmission member 5a. The second power extractor 6b is connected to the second power transmission member 5b.

[0051] When the first fuel cell stack 2a starts generating power, if the first fuel cell stack 2a is in a low-temperature state, the first power extractor 6a selects either the starting current collector plate 13 or the other end current collector plate 12 of the first current collector plate 4a based on the temperature of the first fuel cell stack 2a detected by the temperature sensor 8, and extracts the power generated by the multiple power generation units located between the selected current collector plate and the one end current collector plate 11 to the power transmission unit 7. In other words, when the first power extractor 6a selects either the other end current collector plate 12 or the starting current collector plate 13 of the first current collector plate 4ab, it selects the starting current collector plate 13 if the overall temperature of the first fuel cell stack 2a is not high.

[0052] The second power extractor 6b transmits power to the GPU3 when power generation begins in the second fuel cell stack 2b.

[0053] Figure 4 is a schematic diagram illustrating the various gas flow paths of the fuel cell system 31 in the third embodiment. As shown in Figure 4, the gas flow paths of the fuel cell system 31 in the third embodiment are a fuel supply path 32, an anode gas path 33, an anode off gas path 34, an air supply path 35, a first cathode gas path 36, a second cathode gas path 37, a cathode off gas path 38, a combustion gas supply path 39, an exhaust path 40, and a POx path 41.

[0054] The fuel supply passage 32 is a passage connecting an external fuel tank (not shown) to the inlet of the anode flow path within the first fuel cell stack 2a, and supplies fuel gas to the first fuel cell stack 2a. The fuel gas supplied from the fuel supply passage 32 to the first fuel cell stack 2a is reformed within the first fuel cell stack 2a.

[0055] The anode gas passage 33 is a passage connecting the outlet of an anode flow path (not shown) in the first fuel cell stack 2a and the inlet of an anode flow path (not shown) in the second fuel cell stack 2b. The anode gas passage 33 supplies the fuel gas reformed in the first fuel cell stack 2a to the second fuel cell stack 2b.

[0056] The anode off-gas passage 34 is a passage that connects the outlet of the anode flow path (not shown) in the second fuel cell stack 2 to the combustion gas supply passage 39. The anode off-gas passage 34 supplies the anode off-gas (fuel gas) discharged from the second fuel cell stack 2b to the combustion gas supply passage 39.

[0057] The air supply passage 35 is a passage that sends outside air into the air passage (not shown) inside the GPU3, supplying oxidizer gas to the GPU3. As described above, the oxidizer gas supplied to the GPU3 is heated through heat exchange with the combustion gas burned inside the GPU3.

[0058] The first cathode gas passage 36 is a passage connecting the outlet of the air passage of the GPU 3 to the inlet of the cathode passage (not shown) in the second fuel cell stack 2b. The first cathode gas passage 36 supplies the oxidizer gas heated in the GPU 3 to the second fuel cell stack 2b. That is, the second fuel cell stack 2b is supplied with fuel gas from the anode gas passage 33 and oxidizer gas from the first cathode gas passage 36. This enables the second fuel cell stack 2b to generate electricity.

[0059] The second cathode gas passage 37 is a passage connecting the outlet of the cathode flow path in the second fuel cell stack 2b to the inlet of the cathode flow path (not shown) in the first fuel cell stack 2a. The second cathode gas passage 37 supplies oxidant gas to the first fuel cell stack 2a. That is, the first fuel cell stack 2a is supplied with fuel gas from the fuel supply passage 32 and oxidant gas from the second cathode gas passage 37. As a result, the first fuel cell stack 2a generates electricity.

[0060] The cathode-off gas passage 38 is a passage that connects the outlet of the cathode flow path in the first fuel cell stack 2a to the combustion gas supply passage 39. The cathode-off gas passage 38 supplies the cathode-off gas discharged from the first fuel cell stack 2a to the combustion gas supply passage 39.

[0061] The combustion gas supply passage 39 is a passage that connects the anode-off gas passage 34 and the cathode-off gas passage 38 to the inlet of the combustion gas flow path (not shown) of the GPU3. Within the combustion gas supply passage 39, the anode-off gas (oxidizer gas) supplied from the anode-off gas passage 34 and the cathode-off gas (fuel gas) supplied from the cathode-off gas passage 38 are mixed. The mixed gas in the combustion gas supply passage 39 is supplied as combustion gas to the combustion gas flow path of the GPU3. The combustion gas supplied to the GPU3 from the combustion gas supply passage 39 burns within the GPU3 and becomes harmless exhaust gas, which is discharged to the outside via the exhaust passage 40. In addition, the oxidizer gas flowing through the air flow path of the GPU3 is heated by heat exchange with the burnt combustion gas.

[0062] When the fuel cell system 31 of the third embodiment is started up, a combustion gas mixture of fuel gas and an oxidizer gas for burning the fuel gas is supplied to the combustion gas passage of the GPU 3, and the combustion gas generates heat through catalytic combustion. This warms up the fuel cell stack 2.

[0063] In addition, when the fuel cell system 31 of the third embodiment is started up, fuel and air may be supplied to the GPU 3 using the anode-off gas passage 34 and the cathode-off gas passage 38. Alternatively, a separate gas passage connected to the combustion gas supply passage 39 may be provided, and the fuel and air may be supplied to the GPU 3 from this gas passage via the combustion gas supply passage 39. Furthermore, the first cathode gas passage 36, the second cathode gas passage 37, the cathode-off gas passage 38, the combustion gas supply passage 39, the anode gas passage 33, and the anode-off gas passage 34 may be installed inside the housing of the GPU 3.

[0064] The exhaust passage 40 is a passage that connects the outlet of the combustion gas flow path of the GPU 3 to the outside of the fuel cell system 31, and discharges the exhaust gas emitted from the GPU 3 to the outside.

[0065] The POx channel 41 is a passage that branches off from the air supply channel 35 and connects to the fuel supply channel 32. During the warm-up of the fuel cell system 31 in the third embodiment, it supplies an oxidizer gas for the partial oxidation (POx) reaction to the anode channel of the first fuel cell stack 2a via the fuel supply channel 32. Since POx is an exothermic reaction, when the oxidizer gas is supplied from the POx channel 41 to the fuel gas flowing through the anode channel of the first fuel cell stack 2a and POx is performed, the warm-up of the fuel cell stack 2 is accelerated.

[0066] In this third embodiment of the fuel cell system 31, substantially the same effects and advantages as those of the first embodiment of the fuel cell system 1 described above can be achieved.

[0067] Furthermore, in the third embodiment of the fuel cell system 31, by arranging the starting current collector plate 13 of the first current collector plate 4a so as to sandwich a region where the fuel gas can be reformed and power generation can be performed early, it becomes possible to selectively extract power, reaction heat can be obtained early, and overall the system startup time can be further shortened.

[0068] A fourth embodiment of the present invention will be described using Figure 5. The fuel cell system 45 of the fourth embodiment has substantially the same configuration as the fuel cell system 31 of the third embodiment described above, but as shown in Figure 5, the first current collector plate 4a consists of a one-end current collector plate 11 as the first one-end current collector plate and a other-end current collector plate 12 as the first other-end current collector plate, and the second current collector plate 4b consists of a one-end current collector plate 11 as the second one-end current collector plate, a other-end current collector plate 12 as the second other-end current collector plate and a starting current collector plate 13 as the second starting current collector plate. Figure 5 is a schematic explanatory diagram showing the fuel cell system 45 in the fourth embodiment of the present invention.

[0069] The first power extractor 6a transmits power to the GPU3 when power generation begins in the first fuel cell stack 2a.

[0070] When the second fuel cell stack 2b starts generating power, if the second fuel cell stack 2b is in a low-temperature state, the second power extractor 6b selects either the other end current collector plate 12 of the second current collector plate 4b or the starting current collector plate 13 based on the temperature of the second fuel cell stack 2 calculated using the detection signal from the temperature sensor 8, and extracts the power generated by the multiple power generation units located between the selected current collector plate and the one end current collector plate 11 of the second current collector plate 4b to the power transmission unit 7. In other words, when the second power extractor 6b selects either the other end current collector plate 12 of the second current collector plate 4b or the starting current collector plate 13, it selects the starting current collector plate 13 if the overall temperature of the second fuel cell stack 2b is not high.

[0071] In this fourth embodiment of the fuel cell system 45, substantially the same effects and advantages as those of the third embodiment of the fuel cell system 31 described above can be achieved.

[0072] Furthermore, in the fourth embodiment of the fuel cell system 45, the starting current collector plate 13 is positioned so as to sandwich the vicinity of the GPU3, which heats up particularly quickly, within the second fuel cell stack 2b, which is heated by high-temperature air. This allows power to be extracted from the second fuel cell stack 2b early using the fuel reformed in the first fuel cell stack 2a, enabling early acquisition of reaction heat and overall shortening the system startup time.

[0073] A fifth embodiment of the present invention will be described using Figure 6. The fuel cell system 51 of the fifth embodiment has substantially the same configuration as the fuel cell system 31 of the third embodiment described above, but as shown in Figure 6, the second current collector plate 4b consists of a one-end current collector plate 11 as a second one-end current collector plate, a other-end current collector plate 12 as a second other-end current collector plate, and a starting current collector plate 13 as a second starting current collector plate. Figure 6 is a schematic explanatory diagram showing the fuel cell system 51 in the fifth embodiment of the present invention.

[0074] When the second fuel cell stack 2b starts generating power, if the second fuel cell stack 2b is in a low-temperature state, the second power extractor 6b selects either the other end current collector plate 12 of the second current collector plate 4b or the starting current collector plate 13 based on the temperature of the second fuel cell stack 2b calculated using the detection signal from the temperature sensor 8, and extracts the power generated by the multiple power generation units located between the selected current collector plate and the one end current collector plate 11 of the second current collector plate 4b to the power transmitter 7. In other words, when the second power extractor 6b selects either the other end current collector plate 12 of the second current collector plate 4b or the starting current collector plate 13, it selects the starting current collector plate 13 if the overall temperature of the second fuel cell stack 2b is not high.

[0075] In this fifth embodiment of the fuel cell system 51, substantially the same effects and advantages as those of the third embodiment of the fuel cell system 31 described above can be achieved.

[0076] Furthermore, in the fifth embodiment of the fuel cell system 51, by arranging the current collector plate 4 within the first fuel cell stack 2a and the second fuel cell stack 2b so as to sandwich the region where the fuel gas can be reformed and power generation can be performed at an early stage, it becomes possible to selectively extract power, obtain reaction heat at an early stage, and overall shorten the system startup time.

[0077] A sixth embodiment of the present invention will be described using Figures 7 to 9. Figure 7 is a schematic explanatory diagram showing the fuel cell system 61 in the sixth embodiment of the present invention. Figure 8 is a schematic explanatory diagram showing a plan view of the fuel cell stack 2 of the fuel cell system 61 in the sixth embodiment. Figure 9 is a schematic explanatory diagram showing the power transmission member 5 of the fuel cell system 61 in the sixth embodiment.

[0078] The fuel cell system 61 of the sixth embodiment has substantially the same configuration as the fuel cell system 1 of the first embodiment described above, but as shown in Figure 7, it has an auxiliary structure 62 in which the GPU 3 and the power transmitter 7 are integrated.

[0079] As shown in Figure 7, the auxiliary structure 62 is arranged in series with the fuel cell stack 2 along the stacking direction of the power generation unit. The fuel cell stack 2 is sandwiched between the end plates 9 in the stacking direction of the power generation unit. The auxiliary structure 62 is in contact with the current collector plate 11 at one end.

[0080] The end plate 9, together with the auxiliary structure 62, sandwiches the fuel cell stack 2 in the stacking direction of the power generation unit, and presses the fuel cell stack 2 in the stacking direction of the power generation unit. The end plate 9 is in contact with the current collector plate 12 on the other end.

[0081] Here, as shown in Figure 8, the fuel cell stack 2 has a first side surface 65 and a second side surface 66 that face each other and have a fuel gas flow path 63 through which fuel gas flows along the stacking direction of the power generation units and an oxidant gas flow path 64 through which oxidant gas flows along the stacking direction of the power generation units, respectively, and a third side surface 67 and a fourth side surface 68 that are perpendicular to the first side surface 65 and the second side surface 66 and face each other.

[0082] The fuel cell stack 2 has an open cathode structure in which an oxidizer gas flow path 64, which serves as a manifold, is formed between the casing 69 and a stack of multiple power generation units. The casing 69 is the outer enclosure of the fuel cell stack 2. The fuel gas flow path 63 is formed inside the stack of multiple power generation units.

[0083] As indicated by arrow P in Figure 8, the fuel gas flows from the fuel gas flow path 63a on the second side surface 66 to the fuel gas flow path 63b on the first side surface 65 via the anode flow path within the fuel cell stack 2.

[0084] As indicated by arrow Q in Figure 8, the oxidizer gas flows through the cathode channel within the fuel cell stack 2 from the oxidizer gas channel 64a on the first side surface 65 to the oxidizer gas channel 64b on the second side surface 66. Note that the flow direction of the fuel gas and oxidizer gas may be parallel flow, in addition to the counterflow shown in the figure.

[0085] Furthermore, in the fuel cell system 61 of the sixth embodiment, the power transmission member 5 is composed of an L-shaped member, as shown in Figures 8 and 9. More specifically, in the fuel cell system 61 of the sixth embodiment, the power transmission member 5 has a first side portion 70 located on the same plane as the current collector plate 4 to which it is connected, and a second side portion 71 along the stacking direction of the power generation unit. In the fuel cell system 61 of the sixth embodiment, the first side portion 70 of the power transmission member 5 is connected to the current collector plate 4, and the second side portion 71 is connected to the auxiliary structure 62. The first side portion 70 of the power transmission member 5 is formed to a length that allows it to protrude from the casing 69 of the fuel cell stack 2. The power transmission member 5 in the fuel cell system 61 of the sixth embodiment has rigidity and strength against compressive stress (pressure) along the stacking direction of the power generation unit, and is made of a metallic material that has conductivity, strength, and rigidity, for example.

[0086] As shown in Figures 8 and 9, the power transmission member 5 in the fuel cell system 61 of the sixth embodiment is connected to the current collector plate 4 on the third side surface 67 and the fourth side surface 68 relative to the fuel cell stack 2.

[0087] Furthermore, the power transmission member 5 in the fuel cell system 61 of the sixth embodiment is a plate-shaped member having rigidity and conductivity, and as shown in Figures 8 and 9, it is fixed to the power extractor 6 such that the current collector plate 4 is pressed against the auxiliary structure 62 along the stacking direction of the power generation unit.

[0088] In the fuel cell system 61 of the sixth embodiment, the power transmission member 5 is set so that its coefficient of linear expansion (coefficient of thermal expansion) is equal to that of the fuel cell stack 2.

[0089] In this sixth embodiment of the fuel cell system 61, substantially the same effects and advantages as those of the first embodiment of the fuel cell system 1 described above can be achieved.

[0090] Furthermore, in the fuel cell system 61 of the sixth embodiment, the power transmission member 5 presses the fuel cell stack 2 in the stacking direction of the power generation units, so the power transmission member 5 can partially take over the function of the end plate 9, which presses the fuel cell stack 2 in the stacking direction of the power generation units to bring adjacent power generation units into close contact. As a result, the fuel cell system 61 of the sixth embodiment can reduce the fastening load applied to the end plate 9, and the thickness of the end plate 9 can be reduced.

[0091] Furthermore, in the fuel cell system 61 of the sixth embodiment, the power transmission member 5 can be positioned without interfering with the fuel gas flow path 63 and oxidizer gas flow path 64 formed on the first side surface 65 and the second side surface 66 of the fuel cell stack 2.

[0092] In the fuel cell system 61 of the sixth embodiment, the expansion amounts of the power transmission member 5 and the fuel cell stack 2 can be made equal in the stacking direction of the power generation units, and the absorption mechanism that absorbs the difference in product dimensions due to thermal expansion between the power transmission member 5 and the fuel cell stack 2 in the stacking direction of the power generation units can be omitted. As a result, in the fuel cell system 61 of the sixth embodiment, the power transmission member 5 can be made smaller by the amount that the above absorption mechanism can be omitted, the thermal mass (thermal mass) can be reduced, and overall the system startup time can be shortened.

[0093] In addition, in the fuel cell system 61 of the sixth embodiment, if a protrusion corresponding to the first side portion 70 is provided on the current collector plate side, the power transmission member 5 may be made up of only the second side portion 71.

[0094] Although specific embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0095] For example, since the GPU3 and fuel cell stack2 only need to be in thermal contact, a configuration with space between them is acceptable. In other words, the GPU3 and fuel cell stack2 do not need to be in direct contact (connected) or via an intermediary component.

[0096] For example, in the fuel cell system 1 of the first embodiment, the starting current collector plate 13 may be positioned at the center of the fuel cell stack 2 in the stacking direction of the power generation unit.

[0097] For example, in the fourth and fifth embodiments, the temperature of the second fuel cell stack 2b may be detected by separately providing a temperature sensor that detects the temperature of the oxidizer gas that has passed through the second fuel cell stack 2b.

[0098] For example, in the fuel cell systems 1, 21, 31, 45, 51, and 61 of the first to sixth embodiments, the power transmitter 7 or auxiliary structure 62 may be capable of supplying current to the current collector plate 4 from the power transmitter 7 side. This allows each fuel cell system 1, 21, 31, 45, 51, and 61 to heat the fuel cell stack 2 from the inside with Joule heat generated when current flows through the current collector plate 4, thereby generally shortening the system startup time. [Explanation of Symbols]

[0099] 1…Fuel cell system 2…Fuel cell stack 3…GPU 4…Current collector plate 5...Power transmission component 6…Power extraction device 7…Power transmitter 8…Temperature sensor 9… End plate 10…Battery 11…One end side current collector plate 12... Current collector plate on the other end 13... Starting current collection plate

Claims

1. A fuel cell stack consisting of multiple power generation units stacked on top of each other, which generate electricity by supplying fuel gas and oxidizer gas, A heater that heats the oxidizing gas and is positioned to allow thermal contact with the fuel cell stack, Multiple current collectors that output the electricity generated by the fuel cell stack described above to the outside, A power transmission member connected to the above current collector plate, A power extractor to which the above power transmission member is connected, A power transmission device through which the power generated via the above power extractor is transmitted, It has a temperature detector for detecting the temperature of the fuel cell stack, The multiple current collector plates include one-end current collector plates attached to one end of the fuel cell stack on the side where the heater is located in the stacking direction of the power generation units, other-end current collector plates attached to the other end of the fuel cell stack in the stacking direction of the power generation units, and starting current collector plates sandwiched between adjacent power generation units in the stacking direction of the power generation units. The power extractor described above is capable of selectively combining a plurality of current collectors to transmit power to the power transmitter, and when the fuel cell stack is in a low-temperature state at startup to start generating power in the fuel cell stack, it selects either the startup current collector or the other end current collector based on the temperature of the fuel cell stack detected by the temperature detector, and extracts the power generated by the power generation unit located between the selected current collector and the one end current collector to the power transmitter.

2. The above-mentioned starting current collector plates are arranged one by one at different positions in the stacking direction of the above-mentioned power generation unit. The fuel cell system according to claim 1, characterized in that the power extraction device selects either the starting current collector plate or the other end current collector plate based on the temperature of the fuel cell stack detected by the temperature detector, so as to move sequentially away from one end of the fuel cell stack in the stacking direction of the power generation unit.

3. The fuel cell system according to claim 1 or 2, characterized in that only one starting current collector plate is placed on the fuel cell stack.

4. The fuel cell system according to claim 3, characterized in that the starting current collector plate is positioned at a location offset from the center of the fuel cell stack towards one end of the fuel cell stack in the stacking direction of the power generation unit.

5. The above fuel cell stack consists of a first fuel cell stack and a second fuel cell stack to which the fuel gas that has passed through the first fuel cell stack is supplied. The heater is arranged so as to be able to make thermal contact with the first fuel cell stack and the second fuel cell stack. The current collector plate described above consists of a plurality of first current collector plates that output power generated by the first fuel cell stack to the outside, and a plurality of second current collector plates that output power generated by the second fuel cell stack to the outside. The power transmission member described above consists of a first power transmission member connected to the first current collector plate and a second power transmission member connected to the second current collector plate. The above-mentioned power extractor consists of a first power extractor to which the first power transmission member is connected, and a second power extractor to which the second power transmission member is connected. The first fuel cell stack described above has a reforming catalyst placed in the internal fuel gas flow path. The plurality of first current collector plates are a first one-end current collector plate attached to one end of the first fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, a first other-end current collector plate attached to the other end of the first fuel cell stack in the stacking direction of the power generation unit, and a first starting current collector plate sandwiched between adjacent power generation units of the first fuel cell stack in the stacking direction of the power generation unit. The plurality of second current collector plates are a second one-end current collector plate attached to one end of the second fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, and a second other-end current collector plate attached to the other end of the second fuel cell stack in the stacking direction of the power generation unit. The fuel cell system according to claim 1, characterized in that the first starting current collector plate is positioned at a location offset from the central position of the first fuel cell stack towards one end of the fuel cell stack in the stacking direction of the power generation unit.

6. The above fuel cell stack consists of a first fuel cell stack and a second fuel cell stack to which the fuel gas that has passed through the first fuel cell stack is supplied. The first fuel cell stack is supplied with the oxidizer gas that has passed through the second fuel cell stack. The above-mentioned second fuel cell stack is supplied with oxidizer gas heated by the above-mentioned heater. The heater is arranged so as to be able to make thermal contact with the first fuel cell stack and the second fuel cell stack. The current collector plate described above consists of a plurality of first current collector plates that output power generated by the first fuel cell stack to the outside, and a plurality of second current collector plates that output power generated by the second fuel cell stack to the outside. The power transmission member described above consists of a first power transmission member connected to the first current collector plate and a second power transmission member connected to the second current collector plate. The above-mentioned power extractor consists of a first power extractor to which the first power transmission member is connected, and a second power extractor to which the second power transmission member is connected. The first fuel cell stack described above has a reforming catalyst placed in the internal fuel gas flow path. The plurality of first current collector plates are a first one-end current collector plate attached to one end of the first fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, and a first other-end current collector plate attached to the other end of the first fuel cell stack in the stacking direction of the power generation unit. The plurality of second current collector plates are a second one-end current collector plate attached to one end of the second fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, a second other-end current collector plate attached to the other end of the second fuel cell stack in the stacking direction of the power generation unit, and a second starting current collector plate sandwiched between adjacent power generation units of the second fuel cell stack in the stacking direction of the power generation unit. The fuel cell system according to claim 1, characterized in that the second starting current collector plate is positioned at a location offset from the center of the second fuel cell stack towards one end of the fuel cell stack in the stacking direction of the power generation unit.

7. The above fuel cell stack consists of a first fuel cell stack and a second fuel cell stack to which the fuel gas that has passed through the first fuel cell stack is supplied. The heater is arranged so as to be able to make thermal contact with the first fuel cell stack and the second fuel cell stack. The current collector plate described above consists of a plurality of first current collector plates that output power generated by the first fuel cell stack to the outside, and a plurality of second current collector plates that output power generated by the second fuel cell stack to the outside. The power transmission member described above consists of a first power transmission member connected to the first current collector plate and a second power transmission member connected to the second current collector plate. The above-mentioned power extractor consists of a first power extractor to which the first power transmission member is connected, and a second power extractor to which the second power transmission member is connected. The first fuel cell stack described above has a reforming catalyst placed in the internal fuel gas flow path. The plurality of first current collector plates are a first one-end current collector plate attached to one end of the first fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, a first other-end current collector plate attached to the other end of the first fuel cell stack in the stacking direction of the power generation unit, and a first starting current collector plate sandwiched between adjacent power generation units of the first fuel cell stack in the stacking direction of the power generation unit. The plurality of second current collector plates are a second one-end current collector plate attached to one end of the second fuel cell stack on the side where the heater is located in the stacking direction of the power generation unit, a second other-end current collector plate attached to the other end of the second fuel cell stack in the stacking direction of the power generation unit, and a second starting current collector plate sandwiched between adjacent power generation units of the second fuel cell stack in the stacking direction of the power generation unit. The first starting current collector plate is positioned in the stacking direction of the power generation unit at a location shifted from the center of the first fuel cell stack towards one end of the fuel cell stack. The fuel cell system according to claim 1, characterized in that the second starting current collector plate is positioned at a location offset from the center of the second fuel cell stack towards one end of the fuel cell stack in the stacking direction of the power generation unit.

8. An auxiliary structure in which the above-mentioned heater and the above-mentioned power transmission device are integrated, The power generation unit has an end plate that sandwiches the fuel cell stack with the auxiliary structure in the stacking direction of the power generation unit and presses the fuel cell stack in the stacking direction of the power generation unit, The above auxiliary structure is arranged in series with the fuel cell stack along the stacking direction of the power generation unit. The fuel cell system according to claim 1, characterized in that the power transmission member is fixed to the auxiliary structure such that it presses the current collector plate against the auxiliary structure along the stacking direction of the power generation unit.

9. The fuel cell stack has a rectangular parallelepiped shape and has a first and second side surface facing each other, through which a fuel gas flow path is formed along the stacking direction of the power generation unit and an oxidant gas flow path is formed along the stacking direction of the power generation unit, respectively, and a third and fourth side surface facing each other. The fuel cell system according to claim 8, characterized in that the power transmission member is connected to the current collector plate on the first side and the second side.

10. The fuel cell system according to claim 8, characterized in that the power transmission member has the same coefficient of linear expansion as the fuel cell stack.

11. The fuel cell system according to claim 1, characterized in that the power transmitter can supply current to the starting current collector plate from the power transmitter side.

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