fuel cell system

Abstract

To provide a fuel cell system capable of efficiently discharging, to the outside, residual water generated in a supply passage through which gas is supplied into a fuel cell.SOLUTION: A fuel cell system includes: a fuel cell including a plurality of fuel battery cells; a supply passage through which gas is supplied to the fuel battery cells; a branch connection to branch the supply passage into respective gas passages of the fuel battery cells; a shield part to selectively shield respective gas passages; and a control section supplying scavenging gas to the gas passages to perform scavenging control to discharge moisture in the gas passages. The control section shields at least part of the gas passages by the shield part and supplies scavenging gas to the gas passages.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] In a fuel cell, power generation is performed by an electrochemical reaction between an anode gas such as hydrogen gas and a cathode gas such as oxygen (air), and water is generated along with the electrochemical reaction. The generated water (residual water) remaining in the flow paths of the anode gas and the cathode gas (hereinafter collectively referred to as "reaction gas"), pipes, and components provided in the flow paths hinders the supply of the anode gas and the cathode gas during power generation, and is a factor that deteriorates the power generation performance. Further, when the fuel cell is used below the freezing point, not only is the supply of gas hindered due to the freezing of the residual water, but there is also a risk that the components may be damaged due to the expansion of the residual water when the residual water freezes during stoppage.

[0003] On the other hand, Patent Document 1 discloses a technique for removing moisture present in the hydrogen electrode together with unreacted hydrogen by communicating an off-gas discharge flow path provided in the fuel cell with the outside when power generation of the fuel cell stops, and discharging the off-gas from the off-gas discharge flow path to the outside.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, depending on the form of the flow path for supplying gas to the fuel cell, even when a reaction gas having a flow rate corresponding to the maximum power generation is supplied to the gas flow path, the flow velocity of the reaction gas cannot be sufficiently increased, and the residual water in the fuel cell may not be sufficiently discharged.

[0006] The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a fuel cell system capable of efficiently discharging residual water generated in a supply channel for supplying a reaction gas into a fuel cell to the outside.

Means for Solving the Problems

[0007] In order to solve the above problems, according to one aspect of the present disclosure, a fuel cell including a plurality of fuel cells, a supply channel for supplying gas to the plurality of fuel cells, a branch portion for branching the supply channel into respective gas channels of the plurality of fuel cells, provided at the branch portion a shielding portion for selectively shielding each gas channel, and a control portion for performing scavenging control to supply scavenging gas to the gas channel to discharge moisture in the gas channel, the shielding portion is rotationally controlled by the control portion and includes a closing member capable of supplying gas or scavenging gas to the gas channel through an opening, The opening has at least a first opening formed to be openable without entirely shielding all of the gas flow paths, and a second opening provided at a position different from the first opening and formed to be openable without shielding only one of the gas flow paths. the control portion controls the rotational position of the closing member to control the number of openings or the opening area of the gas channel with respect to the opening, During power generation, the gas is supplied to all of the gas flow paths through the first opening, and during scavenging, the unshielded part of the gas flow path is through the second opening A fuel cell system is provided that supplies scavenging gas to the gas channel.

Advantages of the Invention

[0008] As described above, according to the present disclosure, residual water generated in the supply channel for supplying the reaction gas into the fuel cell can be efficiently discharged to the outside.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0011] <1. Example of overall configuration of fuel cell system> First, an example of the overall configuration of a fuel cell system according to a first embodiment of the present disclosure will be described. Fig. 1 is a schematic diagram showing an example of the overall configuration of a fuel cell system 1 according to this embodiment. The fuel cell system 1 is, for example, a system mounted on a fuel cell vehicle, but is not limited to this example.

[0012] The fuel cell system 1 includes a cathode gas (oxidizing gas) path 11, an anode gas (fuel gas) path 20, a fuel cell 10 having a plurality of fuel cell cells, and a control unit 50 that controls the entire system. The fuel cell system 1 generates electricity by supplying an anode gas and a cathode gas to the fuel cell 10 and causing an electrochemical reaction between the anode gas and the cathode gas within the fuel cell. The fuel cell system 1 also includes a refrigerant path (not shown) that supplies a refrigerant to the fuel cell 10 to cool it, and a power system (not shown) that charges and discharges power for the system. The power system includes a current sensor that detects the value of the current generated by the fuel cell 10. In this embodiment, an example will be described in which hydrogen gas is used as the anode gas and air (oxygen) is used as the cathode gas.

[0013] The fuel cell 10 is configured as a polymer electrolyte fuel cell, for example, and has a stack structure in which a plurality of fuel cells are stacked. Each fuel cell has an oxygen electrode on one side of an electrolyte made of an ion exchange membrane and a hydrogen electrode on the other side. Further, the fuel cell has a pair of separators arranged so as to sandwich the oxygen electrode and the hydrogen electrode. Hydrogen gas is supplied to the hydrogen gas flow path of one separator, and air is supplied to the air flow path of the other separator, and the fuel cell 10 generates electricity by the supplied hydrogen gas and air reacting with each other.

[0014] The cathode gas path 11 includes an air supply flow path 12 through which air supplied to the fuel cell 10 flows and an air discharge flow path 18 through which the oxidized off-gas discharged from the fuel cell 10 flows. The air supply flow path 12 includes a compressor 15 that takes in air via an air filter 13. The air supply flow path 12 branches at a branch portion (not shown) and is connected to the respective air flow paths of the plurality of fuel cells. Further, the respective air flow paths of the plurality of fuel cells merge at a merging portion (not shown) and are connected to the air discharge flow path 18. The oxidized off-gas flowing through the air discharge flow path 18 is discharged into the atmosphere.

[0015] The anode gas path 20 includes a hydrogen supply source 21, a hydrogen supply flow path 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 10 flows, a circulation flow path 28 for returning the hydrogen off-gas discharged from the fuel cell 10 to the hydrogen supply flow path 22, a circulation pump 25 for pumping the hydrogen off-gas in the circulation flow path 28 to the hydrogen supply flow path 22, and a discharge flow path 31 branched and connected from the circulation flow path 28.

[0016] The hydrogen supply source 21 is composed of, for example, a high-pressure tank or a hydrogen storage alloy, etc., and stores high-pressure hydrogen gas. The hydrogen supply flow path 22 is provided with a pressure regulating valve 23 that regulates the pressure of the hydrogen gas supplied to the fuel cell 10. The pressure regulating valve 23 may be, for example, a pressure reducing valve that reduces the pressure of the hydrogen gas to a preset pressure. A shut-off valve for switching the supply of hydrogen gas to the fuel cell 10 may be provided upstream of the pressure regulating valve 23. Also, an upstream pressure sensor 24 for detecting the pressure of the hydrogen gas in the hydrogen supply flow path 22 is provided on the downstream side of the pressure regulating valve 23 and upstream of the confluence of the hydrogen supply flow path 22 and the circulation flow path 28. Further, a temperature sensor for detecting the temperature of the hydrogen gas in the hydrogen supply flow path 22 may be provided in the hydrogen supply flow path 22. The hydrogen supply flow path 22 branches at a branching portion (not shown) and is connected to the respective hydrogen gas flow paths of a plurality of fuel cell cells. Also, the respective hydrogen gas flow paths of the plurality of fuel cell cells merge at a confluence portion (not shown) and are connected to the circulation flow path 28.

[0017] The circulation pump 25 is driven by the control unit 50 to circulate the hydrogen gas in the circulation flow path 28 to the fuel cell 10. A gas-liquid separator 27 is provided in the circulation flow path 28. The gas-liquid separator 27 recovers moisture from the hydrogen off-gas. A discharge flow path 31 is connected to the gas-liquid separator 27, and a purge valve 33 is provided in the discharge flow path 31. The purge valve 33 is driven to open and close by the control unit 50 to discharge the moisture recovered by the gas-liquid separator 27 and the hydrogen off-gas in the circulation flow path 28 to the outside. The discharged hydrogen off-gas is discharged into the atmosphere. A downstream pressure sensor 29 is provided on the downstream side of the purge valve 33.

[0018] The control unit 50 is configured to include one or more processors such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and one or more storage devices that store software programs, control parameters, acquired information, and the like. The storage device may include storage elements such as a RAM (Random Access Memory) and a ROM (Read Only Memory), or may include a storage medium such as a CD-ROM or a storage device.

[0019] The control unit 50 performs scavenging control to supply scavenging gas to the air flow path and the hydrogen gas flow path of a plurality of fuel cells, and discharge moisture (residual water) remaining in the air flow path and the hydrogen gas flow path to the outside. Specifically, at an arbitrary timing when scavenging is determined to be necessary, the control unit 50 opens the back pressure regulating valve 17 provided in the air discharge flow path 18 of the cathode gas path 11, and supplies air (scavenging gas) into the fuel cell 10 through the air supply flow path 12, and discharges the residual water adhering to the air flow path in the fuel cell 10 by utilizing the pressure of the air. Further, at an arbitrary timing when scavenging is determined to be necessary, the control unit 50 opens the purge valve 33 provided in the discharge flow path 31 of the anode gas path 20, and supplies hydrogen gas (scavenging gas) into the fuel cell 10 through the hydrogen supply flow path 22, and discharges the residual water adhering to the hydrogen gas flow path in the fuel cell 10 by utilizing the pressure of the hydrogen gas.

[0020] In the fuel cell system 1 according to the present embodiment, when executing scavenging control, the control unit 50 controls a shielding unit that selectively shields at least a part of the gas flow paths among the respective gas flow paths of a plurality of fuel cells, shields at least a part of the gas flow paths, and supplies scavenging gas to the gas flow paths of the fuel cells. Thereby, the flow velocity of the scavenging gas is increased, and the residual water adhering to the gas flow path can be efficiently discharged to the outside. Hereinafter, the shielding unit will be described in detail.

[0021] <2. Configuration Example of Shielding Unit> Figs. 2 to 5 are explanatory views showing a configuration example of a shielding portion 80 provided in the fuel cell system 1 according to the present embodiment. The shielding portion 80 according to the present embodiment is provided in the air supply manifold 75i and the hydrogen supply manifold 77i. Fig. 2 is a perspective view schematically showing the fuel cell 10. Fig. 3 is a cross-sectional view of a fuel cell 71 constituting the fuel cell 10. Fig. 4 is a schematic view showing a configuration example of the oxygen electrode 63 of the fuel cell 71. Fig. 5 is an explanatory view showing a configuration example of a closing member 81 constituting the shielding portion 80.

[0022] As shown in Fig. 2, the fuel cell 10 includes a plurality of fuel cells 71a to 71f and an end plate 73. For ease of understanding of the description, hereinafter, the fuel cell 10 will be described as including six fuel cells 71a to 71f, but the number of fuel cells is not particularly limited. In the following description, when no particular distinction is required, the plurality of fuel cells 71a to 71f are collectively referred to as the fuel cell 71.

[0023] The fuel cell 10 has a stack structure in which a plurality of fuel cells 71 are stacked and arranged on the end plate 73. The end plate 73 has a function of holding a plurality of fuel cells 71 in cooperation with a case or a frame (not shown). The fuel cell 10 has an air supply manifold 75i, a refrigerant supply manifold 79i, a hydrogen supply manifold 77i, an air discharge manifold 75o, a refrigerant discharge manifold 79o, and a hydrogen discharge manifold 77o provided so as to penetrate all the fuel cells 71. The air supply manifold 75i and the hydrogen supply manifold 77i each have a function as a branch portion of the present disclosure.

[0024] An air supply manifold 75i is connected to an air supply passage 12, and air pumped by a compressor 15 is supplied to the air supply manifold 75i. Further, a plurality of air passages provided in respective fuel cell cells 71 are connected to the air supply manifold 75i, and the air pumped by the compressor 15 is supplied to the respective air passages via the air supply manifold 75i. Further, each air passage is connected to an air discharge manifold 75o, and the air supplied to the air passage becomes oxidation off-gas by an electrochemical reaction and is discharged to the air discharge manifold 75o.

[0025] A hydrogen supply manifold 77i is connected to a hydrogen supply passage 22, and hydrogen gas supplied from a hydrogen supply source 21 is supplied to the hydrogen supply manifold 77i. Further, a plurality of hydrogen gas passages provided in respective fuel cell cells 71 are connected to the hydrogen supply manifold 77i, and the hydrogen gas supplied from the hydrogen supply source 21 is supplied to the respective hydrogen gas passages via the hydrogen supply manifold 77i. Further, each hydrogen gas passage is connected to a hydrogen discharge manifold 77o, and the hydrogen gas supplied to the hydrogen gas passage becomes hydrogen off-gas by an electrochemical reaction and is discharged to the hydrogen discharge manifold 77o. The hydrogen discharge manifold 77o is connected to a circulation passage 28, and a part of the discharged hydrogen off-gas is returned to the hydrogen supply passage 22, and the other part is released into the atmosphere.

[0026] A refrigerant supply manifold 79i is connected to a refrigerant circulation passage (not shown), and refrigerant pumped by a refrigerant pump or the like is supplied to the refrigerant supply manifold 79i. Further, a plurality of refrigerant passages provided in respective fuel cell cells 71 are connected to the refrigerant supply manifold 79i, and the refrigerant pumped by a refrigerant pump or the like is supplied to the respective refrigerant passages via the refrigerant supply manifold 79i. Further, each refrigerant passage is connected to a refrigerant discharge manifold 79o, and the refrigerant supplied to the refrigerant passage is discharged to the refrigerant discharge manifold 79o. The refrigerant discharge manifold 79o is connected to the refrigerant circulation passage, and the discharged refrigerant circulates through the refrigerant circulation passage.

[0027] The hydrogen supply manifold 77i is provided with a first shielding portion 80a, and the air supply manifold 75i is provided with a second shielding portion 80b. Since the first shielding portion 80a and the second shielding portion 80b may have the same configuration, hereinafter, they will simply be referred to as the shielding portion 80, and the configuration of the shielding portion 80 provided in the air supply manifold 75i will be described.

[0028] The shielding portion 80 includes a closing member 81 provided in the air supply manifold 75i and a motor 83 that axially rotates the closing member 81. The closing member 81 is disposed in the air supply manifold 75i so as to penetrate through a plurality of fuel cell cells 71. The end of the closing member 81 on the end plate 73 side is connected to a motor 83 attached to the end plate 73, and the closing member 81 is disposed in the air supply manifold 75i so as to be axially rotatable. The motor 83 is a motor whose rotation angle can be controlled by the control unit 50. The motor 83 may be, for example, a stepping motor.

[0029] The closing member 81 is a hollow cylindrical member and has an opening 81a on its circumferential surface. The air supply manifold 75i is formed in a cylindrical shape as a whole, and the cylindrical closing member 81 rotates axially inside. The air supplied to the air supply manifold 75i flows through the internal space of the closing member 81 and is supplied to the air flow path 74 (see FIG. 5) of each fuel cell cell 71 through the opening 81a. That is, among the plurality of air flow paths provided in each fuel cell cell 71, the air flow paths that do not face the opening 81a are shielded by the closing member 81. Note that the state shielded by the closing member 81 does not have to be a completely airtight state, and it may be a state in which the air flow is obstructed.

[0030] FIG. 3 is a cross-sectional view of one fuel cell 71 at a position where a hydrogen supply manifold 77i and an air supply manifold 75i where a shielding portion 80 is disposed are provided. Each fuel cell 71 includes a hydrogen electrode 61, an oxygen electrode 63, and a cooling plate 65. The hydrogen electrode 61 and the oxygen electrode 63 are arranged with the electrolyte membrane 69 interposed therebetween. Further, a first separator 67a and a second separator 67b are arranged so as to sandwich the hydrogen electrode 61, the electrolyte membrane 69, and the oxygen electrode 63. Further, a cooling plate 65 and a third separator 67c are arranged on the outer surface of the second separator 67b.

[0031] The hydrogen electrode 61 has a plurality of hydrogen gas flow paths 76 connected to a hydrogen supply flow path 22 via a hydrogen supply manifold 77i. The hydrogen gas supplied to each hydrogen gas flow path 76 passes through a reaction region 72 (see FIG. 2) and is discharged to a circulation flow path 28 via a hydrogen discharge manifold 77o. The oxygen electrode 63 has a plurality of air flow paths 74 connected to an air supply flow path 12 via an air supply manifold 75i. The air supplied to each air flow path 74 passes through a reaction region 72 (see FIG. 2) and is discharged to an air discharge flow path 18 via an air discharge manifold 75o. Further, the cooling plate 65 has a plurality of refrigerant flow paths 78 connected to a refrigerant circulation flow path via a refrigerant supply manifold 79i. The refrigerant supplied to each refrigerant flow path 78 passes through a reaction region 72 (see FIG. 2) and is returned to the refrigerant circulation flow path via a refrigerant discharge manifold 79o.

[0032] The plurality of stacked fuel cells 71 are each configured as shown in FIG. 3, and a plurality of hydrogen gas flow paths 76 of each fuel cell 71 open to the hydrogen supply manifold 77i, a plurality of air flow paths 74 of each fuel cell 71 open to the air supply manifold 75i, and a plurality of refrigerant flow paths 78 of each fuel cell 71 open to the refrigerant supply manifold 79i.

[0033] FIG. 4 is a plan view schematically showing a configuration example of the oxygen electrode 63 constituting the fuel cell 71. A plurality of air flow paths 74 provided in the oxygen electrode 63 are each formed such that both ends thereof open to the air supply manifold 75i and the air discharge manifold 75o. That is, each air flow path 74 is provided independently without merging in the middle. Therefore, by shielding the end portion of each air flow path 74 that opens to the air supply manifold 75i among both end portions, air is not supplied to the shielded air flow path 74. Although not shown, a plurality of hydrogen gas flow paths 76 provided in the hydrogen electrode 61 are formed in the same manner. In FIG. 4, an example in which the air electrode 63 has six air flow paths 74 is shown, but actually more air flow paths are formed.

[0034] FIG. 5 is an explanatory view showing a developed hollow cylindrical closing member 81. FIG. 5 schematically shows the air flow paths 74 (74a to 74f) of six fuel cells 71 (71a to 71f) that open to the air supply manifold 75i. In FIG. 5, for ease of understanding the explanation, illustration of the components of the fuel cell 71 other than the air flow path 74 is omitted. Further, FIG. 5 shows an example in which each fuel cell 71 (71a to 71f) has three air flow paths 74 (74a to 74f). The angle shown in FIG. 5 indicates the rotation angle with the rotational phase of the circumferential center line of the first opening 81a in the non-energized state of the motor 83 being set to 0°. In the following description, when no particular distinction is required, the air flow paths 74a to 74f are collectively referred to as the air flow path 74.

[0035] The closing member 81 has a first opening 81a and a second opening 81b. The first opening 81a is disposed at a position where the rotational phase of the circumferential center line is 0°. The first opening 81a is formed to have a size that can be opened without shielding all the air flow paths 74a to 74f of all the fuel cells 71a to 71f. The second opening 81b is disposed at a position where the rotational phase of the circumferential center line is 180°. The second opening 81b is formed to have a size that can be opened without shielding only one of the three air flow paths 74a to 74f of each fuel cell 71a to 71f.

[0036] Referring to FIGS. 5 to 7, the operation of the shielding portion 80 will be described.

[0037] FIG. 5 shows the rotational position of the closing member 81 when the fuel cell system 1 is started and the fuel cell 10 generates power. In this case, the first opening 81a is opened without shielding all the air flow paths 74a to 74f of all the fuel cells 71a to 71f, enabling the supply of air to all the air flow paths 74a to 74f. Therefore, power generation using all the fuel cells 71a to 71f is not hindered.

[0038] FIGS. 6 and 7 show examples of the rotational position of the closing member 81 when discharging moisture adhering in the air flow paths 74a to 74f. FIG. 6 shows the rotational position of the closing member 81 rotated 165° from the rotational position of the closing member 81 shown in FIG. 5. In the state shown in FIG. 6, the second opening 81b is opened without shielding only the air flow path 74 in the right column among the three air flow paths 74a to 74f of each fuel cell 71a to 71f, and shields the remaining two columns of air flow paths.

[0039] Further, FIG. 7 shows the rotational position of the closing member 81 rotated 180° from the rotational position of the closing member 81 shown in FIG. 5. In the state shown in FIG. 7, the second opening 81b is opened without shielding only the air flow path 74 in the central column among the three air flow paths 74a to 74f of each fuel cell 71a to 71f, and shields the remaining two columns of air flow paths. Although not shown, by further rotating the closing member 81 by 15°, the second opening 81b is opened without shielding only the air flow path 74 in the left column among the three air flow paths 74a to 74f of each fuel cell 71a to 71f, and shields the remaining two columns of air flow paths.

[0040] Thus, when scavenging control is performed by supplying air (scavenging gas) pumped by the compressor 15 to the fuel cell 10, the total opening area of the air flow path 74 through which the scavenging gas is supplied can be reduced. Therefore, when the flow rate or pressure of the scavenging gas is the same, the flow velocity of the scavenging gas passing through the air flow path 74 through which the scavenging gas is supplied can be increased. As a result, the certainty of discharging the moisture adhering to the inner peripheral surface of the air flow path 74 by the scavenging gas can be enhanced.

[0041] Note that in the shielding part 80 according to the above embodiment, the air supply manifold 75i is circular, and the closing member 81 is cylindrical. However, as long as the closing member 81 can rotate axially within the air supply manifold 75i, the shapes of the air supply manifold 75i and the closing member 81 are not limited to cylindrical. Further, even when all of the plurality of air flow paths 74 shown in FIG. 4 are not independent, the air flow paths 74 may be formed such that there are a plurality of groups of air flow paths 74 communicating with each other. In this case, by shielding the inlet of the air flow path 74 so that air (scavenging gas) is not supplied to some of the groups of air flow paths 74 among the plurality of groups of air flow paths 74, the air flow rate of the air in the air flow path to which air is supplied can be increased.

[0042] <3. Modification Example> So far, the configuration example of the shielding part 80 has been described. However, the shielding part 80 of the fuel cell system 1 according to the present embodiment can be variously modified. Some of the modification examples will be described below.

[0043] (3-1. First Modification Example) FIGS. 8 to 10 are diagrams for explaining a first modification example of the shielding part, and are explanatory diagrams showing a hollow cylindrical closing member 81 developed. The shielding part according to the first modification example is different from the closing member 81 of the shielding part 80 according to the above embodiment in the configuration of the closing member 81. FIGS. 8 to 10 are diagrams corresponding to FIGS. 5 to 7 above.

[0044] The blocking member 81 has a first opening 81a, a second opening 81c, a third opening 81d, and a fourth opening 81e. The first opening 81a is disposed at a position where the rotational phase of the circumferential center line is 0°. The first opening 81a is formed to have a size that can be opened without blocking all the air flow paths 74a to 74f of all the fuel cells 71a to 71f.

[0045] The second opening 81c is disposed at a position where the rotational phase of the circumferential center line is 120°. The second opening 81c is formed to have a size that can be opened without blocking only one of the three air flow paths 74a and 74b of the two fuel cells 71a and 71b. The third opening 81d is disposed at a position where the rotational phase of the circumferential center line is 165°. The third opening 81d is formed to have a size that can be opened without blocking only one of the three air flow paths 74c and 74d of the two fuel cells 71c and 71d. The fourth opening 81e is disposed at a position where the rotational phase of the circumferential center line is 210°. The fourth opening 81e is formed to have a size that can be opened without blocking only one of the three air flow paths 74e and 74f of the two fuel cells 71e and 71f.

[0046] FIG. 8 shows the rotational position of the blocking member 81 when the fuel cell system 1 is started and the fuel cell 10 generates power. In this case, the first opening 81a is opened without blocking all the air flow paths 74a to 74f of all the fuel cells 71a to 71f, enabling the supply of air to all the air flow paths 74a to 74f. Therefore, power generation using all the fuel cells 71a to 71f is not hindered.

[0047] FIGS. 9 and 10 show examples of the rotational position of the blocking member 81 when discharging moisture adhering in the air flow paths 74a and 74b. FIG. 9 shows the rotational position of the blocking member 81 rotated 230° from the rotational position of the blocking member 81 shown in FIG. 8. In the state shown in FIG. 9, the second opening 81c is opened without blocking only the air flow path 74 in the right column among the three air flow paths 74a and 74b of the two fuel cells 71a and 71b, and blocks the remaining two columns of air flow paths.

[0048] Further, FIG. 10 shows the rotational position of the closing member 81 rotated 245° from the rotational position of the closing member 81 shown in FIG. 8. In the state shown in FIG. 10, the second opening 81c opens without shielding only the air flow path 74 in the central row among the three air flow paths 74a and 74b of the two fuel cell cells 71a and 71b, and shields the remaining two rows of air flow paths. Although not shown, by further rotating the closing member 81 by 15°, the second opening 81c opens without shielding only the air flow path 74 in the left column among the three air flow paths 74a and 74b of the two fuel cell cells 71a and 71b, and shields the remaining two rows of air flow paths. Similarly, by adjusting the rotation angle of the closing member 81, any two of the air flow paths 74c to 74f of the other fuel cell cells 71c to 71f can be opened without shielding and the remaining air flow paths can be shielded.

[0049] Thereby, when performing scavenging control by supplying air (scavenging gas) pumped by the compressor 15 to the fuel cell 10, the total opening area of the air flow paths 74 to which the scavenging gas is supplied can be reduced. According to the configuration of the shielding portion according to the first modification, the total opening area of the air flow paths 74 to which the scavenging gas is supplied can be further reduced compared to the shielding portion 80 according to the above-described embodiment. Therefore, when the flow rate or pressure of the scavenging gas is the same, the flow velocity of the scavenging gas passing through the air flow paths 74 to which the scavenging gas is supplied can be increased. Thereby, the certainty of discharging the moisture adhering to the inner peripheral surface of the air flow path 74 by the scavenging gas can be further enhanced.

[0050] (3-2. Second Modification) FIGS. 11 to 13 are diagrams for explaining a second modification of the shielding portion, and are explanatory diagrams showing the hollow cylindrical closing members 81A to 81C developed. The shielding portion according to the second modification is different from the shielding portion 80 according to the above-described embodiment in that three closing members 81A to 81C are used. FIGS. 11 to 13 are diagrams corresponding to FIGS. 5 to 7 described above.

[0051] The three blocking members 81A to 81C each have a first opening 81Aa, 81Ba, 81Ca and a second opening 81Af, 81Bf, 81Cf. The first openings 81Aa, 81Ba, 81Ca are arranged at positions where the rotational phase of the circumferential center line is 0°. The first opening 81Aa of the blocking member 81A is formed to have a size that can be opened without blocking all of the air flow paths 74a, 74b of the two fuel cell cells 71a, 71b. The second opening 81Af of the blocking member 81A is arranged at a position where the rotational phase of the circumferential center line is 120°. The second opening 81Af is formed to have a size that can be opened without blocking only one of the three air flow paths 74a, 74b of the two fuel cell cells 71a, 71b.

[0052] The first opening 81Ba of the blocking member 81B is formed to have a size that can be opened without blocking all of the air flow paths 74c, 74d of the two fuel cell cells 71c, 71d. The second opening 81Bf of the blocking member 81B is arranged at a position where the rotational phase of the circumferential center line is 120°. The second opening 81Bf is formed to have a size that can be opened without blocking only one of the three air flow paths 74c, 74d of the two fuel cell cells 71c, 71d. Further, the first opening 81Ca of the blocking member 81C is formed to have a size that can be opened without blocking all of the air flow paths 74e, 74f of the two fuel cell cells 71e, 71f. The second opening 81Cf of the blocking member 81C is arranged at a position where the rotational phase of the circumferential center line is 120°. The second opening 81Cf is formed to have a size that can be opened without blocking only one of the three air flow paths 74e, 74f of the two fuel cell cells 71e, 71f.

[0053] FIG. 11 shows the rotational positions of the closing members 81A to 81C when the fuel cell system 1 is started and the fuel cell 10 generates power. In this case, all the first openings 81Aa to 81Ca of all the closing members 81A to 81C are opened without shielding all the air flow paths 74a to 74f of all the fuel cells 71a to 71f, enabling the supply of air to all the air flow paths 74a to 74f. Therefore, power generation using all the fuel cells 71a to 71f is not hindered.

[0054] FIGS. 12 and 13 show examples of the rotational positions of the closing members 81A to 81C when discharging moisture adhering in the air flow paths 74a and 74b. FIG. 12 shows a state where the closing member 81A is rotated 230° and the closing members 81B to 81C are rotated 90° from the rotational positions of the closing members 81A to 81C shown in FIG. 11. In the state shown in FIG. 12, the second opening 81Af of the closing member 81A is opened without shielding only the air flow path 74 in the right column among the three air flow paths 74a and 74b of the two fuel cells 71a and 71b, and shields the remaining two columns of air flow paths. The air flow paths 74c to 74f of the other fuel cells 71c to 71f are shielded by the closing members 81B to 81C.

[0055] Further, FIG. 13 shows a state where the closing member 81A is rotated 245° and the closing members 81B to 81C are rotated 90° from the rotational positions of the closing members 81A to 81C shown in FIG. 11. In the state shown in FIG. 13, the second opening 81Af of the closing member 81A is opened without shielding only the air flow path 74 in the central column among the three air flow paths 74a and 74b of the two fuel cells 71a and 71b, and shields the remaining two columns of air flow paths. The air flow paths 74c to 74f of the other fuel cells 71c to 71f are shielded by the closing members 81B to 81C. Although not shown, by further rotating the closing member 81A by 15°, the second opening 81Af of the closing member 81A is opened without shielding only the air flow path 74 in the left column among the three air flow paths 74a and 74b of the two fuel cells 71a and 71b, and shields the remaining two columns of air flow paths.

[0056] Similarly, by adjusting the rotation angles of the three closing members 81A to 81C respectively, any two of the air flow paths 74c to 74f of the other fuel cell cells 71c to 71f can be opened without shielding, and the remaining air flow paths can be shielded. Further, by adjusting the rotation angles of the three closing members 81A to 81C respectively, any four or six of the air flow paths 74a to 74f of all the air flow paths 74 of the fuel cell cells 71a to 71f can be opened without shielding, and the remaining air flow paths can be shielded.

[0057] According to the configuration of the shielding part according to the second modification example, the total opening area of the air flow path 74 to which the scavenging gas is supplied can be made smaller than that of the shielding part 80 according to the above embodiment. Therefore, when the flow rate or pressure of the scavenging gas is the same, the flow velocity of the scavenging gas passing through the air flow path 74 to which the scavenging gas is supplied can be made faster. Thereby, the certainty of discharging the moisture adhering to the inner peripheral surface of the air flow path 74 by the scavenging gas can be further enhanced. Further, according to the configuration of the shielding part according to the second modification example, the degree of freedom in adjusting the total opening area of the air flow path to which the scavenging gas is supplied is increased. Therefore, even when the flow rate or pressure of the scavenging gas is the same, for example, according to the remaining water amount, the flow velocity of the scavenging gas passing through the air flow path 74 to which the scavenging gas is supplied can be adjusted.

[0058] (3-3. Third Modification Example) Figs. 14 to 17 are diagrams for explaining a third modification example of the shielding part. Fig. 14 is a diagram schematically showing a cross section of the fuel cell 10 along the axial direction of the air supply manifold 75i. Figs. 15 to 17 are explanatory diagrams showing operation examples of the shielding part 90 according to the third modification example, and are explanatory diagrams showing the belt-shaped closing member 91 developed.

[0059] The shielding part 90 according to the third modification example includes a belt-shaped closing member 91, two rotors 85a and 85b provided on the first end plate 73a, and two rotors 85c and 85d provided on the second end plate 73b. At least one of the total four rotors 85a to 85d is connected to a motor (not shown), and the rotors 85a to 85d are rotated by driving the motor by the control unit 50, so that the closing member 91 rotates.

[0060] The belt-shaped closing member 91 has a first opening 91a, a second opening 91b, a third opening 91c, and a fourth opening 91d. The first opening 91a, the second opening 91b, the third opening 91c, and the fourth opening 91d are provided at different positions in the length direction of the belt-shaped closing member 91, respectively. Among these, the first opening 91a is formed to have a size that can be opened without shielding all the air flow paths 74a to 74f of all the fuel cell cells 71a to 71f.

[0061] The second opening 91b is formed to have a size that can be opened without shielding only the air flow paths 74 of the upper row of any two of the three air flow paths 74a to 74f of each of the six fuel cell cells 71a to 71f. The third opening 91c is formed to have a size that can be opened without shielding only the air flow paths 74 of the middle row of any two of the three air flow paths 74a to 74f of each of the six fuel cell cells 71a to 71f. The fourth opening 91d is formed to have a size that can be opened without shielding only the air flow paths 74 of the lower row of any two of the three air flow paths 74a to 74f of each of the six fuel cell cells 71a to 71f.

[0062] FIG. 15 shows the position of the closing member 91 when the fuel cell system 1 is activated and the fuel cell 10 generates power. In this case, the first opening 91a is opened without shielding all the air flow paths 74a to 74f of all the fuel cell cells 71a to 71f, enabling the supply of air to all the air flow paths 74a to 74f. Therefore, power generation using all the fuel cell cells 71a to 71f is not hindered.

[0063] FIGS. 16 and 17 show examples of the rotational positions of the closing member 91 when discharging moisture adhering to the air flow path 74. In the state shown in FIG. 16, the first opening 91a is opened without shielding all three air flow paths 74a and 74b of the two fuel cell cells 71a and 71b, and the second opening 91b is opened without shielding only the upper row air flow path 74 among the three air flow paths 74e and 74f of the two fuel cell cells 71e and 71f. The other air flow paths 74 are shielded by the closing member 91.

[0064] Also, in the state shown in FIG. 17, the second opening 91b is opened without shielding only the upper row air flow path 74 among the three air flow paths 74c and 74d of the two fuel cell cells 71c and 71d, and the third opening 91c is opened without shielding only the middle row air flow path 74 among the three air flow paths 74e and 74f of the two fuel cell cells 71e and 71f. The other air flow paths 74 are shielded by the closing member 91. In addition, although not shown, by adjusting the rotational position of the closing member 91, any one of the air flow paths 74 of the fuel cell cell 71 can be opened without shielding, and the remaining air flow paths can be shielded.

[0065] Thereby, when performing scavenging control by supplying air (scavenging gas) pumped by the compressor 15 to the fuel cell 10, the total opening area of the air flow paths 74 to which the scavenging gas is supplied can be reduced. Therefore, when the flow rate or pressure of the scavenging gas is the same, the flow velocity of the scavenging gas passing through the air flow paths 74 to which the scavenging gas is supplied can be made faster. Thereby, the certainty of discharging the moisture adhering to the inner peripheral surface of the air flow path 74 by the scavenging gas can be further enhanced.

[0066] Note that the opening provided in the closing member 91 of the shielding portion 90 according to the third modification example is not limited to the above example. FIGS. 18 to 19 show examples of the closing member 91 with different forms of the opening. As shown in FIGS. 18 to 19, apart from the first opening 91a that opens all the air flow paths 74 when generating power, one second opening 91e having a size that allows two of the three air flow paths 74 of any two fuel cell units 71 to be opened without being shielded may be provided. According to the closing member 91 having such a second opening 91e, when supplying air (scavenging gas) pumped by the compressor 15 to the fuel cell 10 for scavenging control, the scavenging gas can be supplied to the air flow path 74 while selecting two fuel cell units 71. In the closing member 91 of the shielding portion 90 according to the third modification example, apart from the examples shown in FIGS. 18 to 19, openings may be formed at appropriate positions and sizes.

[0067] (3-4. Fourth Modification Example) FIGS. 20 to 21 are diagrams for explaining a fourth modification example of the shielding portion. FIGS. 20 to 21 are diagrams schematically showing a cross-section of the fuel cell 10 along the axial direction of the air supply manifold 75i, and are explanatory diagrams showing an operation example of the shielding portion 95 according to the fourth modification example.

[0068] The shielding portion 95 according to the fourth modification example includes a closing member 98 disposed in the air supply manifold 75i and an actuator 96 that moves the closing member 98 forward and backward. The form of the closing member 98 is not particularly limited as long as it can shield the air flow path 74 of at least one fuel cell unit 71 at an appropriate position in the air supply manifold 75i. The actuator 96 is controlled to be driven by the control unit 50 to move the closing member 98 forward and backward. The actuator 96 shown in FIGS. 20 to 21 is an actuator of a type that expands and contracts a telescopic pole 99 with the closing member 98 attached to its tip. The means for expanding and contracting the pole 99 may be an appropriate means such as a motor, a hydraulic mechanism, or a pneumatic mechanism.

[0069] Figure 20 shows the position of the blocking member 98 when the fuel cell system 1 is started and the fuel cell 10 generates power. In this case, the blocking member 98 opens without shielding all the air flow paths 74a to 74f of all the fuel cell cells 71a to 71f, enabling the supply of air to all the air flow paths 74a to 74f. Therefore, power generation using all the fuel cell cells 71a to 71f is not hindered.

[0070] Figure 21 shows an example of the position of the blocking member 98 when discharging moisture adhering to the air flow path 74. In the state shown in Figure 21, the blocking member 98 shields all three air flow paths 74c and 74d of two fuel cell cells 71c and 71d, while the other air flow paths 74 are opened without being shielded by the blocking member 98. Although not shown, by appropriately changing the position of the blocking member 98, the air flow paths 74 to be shielded can be changed. Thereby, when performing scavenging control by supplying air (scavenging gas) pumped by the compressor 15 to the fuel cell 10, the total opening area of the air flow paths 74 to which the scavenging gas is supplied can be reduced. Therefore, when the flow rate or pressure of the scavenging gas is the same, the flow velocity of the scavenging gas passing through the air flow paths 74 to which the scavenging gas is supplied can be increased. Thereby, the certainty of discharging the moisture adhering to the inner peripheral surface of the air flow path 74 by the scavenging gas can be further enhanced.

[0071] Note that the size of the blocking member 98 is not limited to the above example. By appropriately selecting the size of the blocking member 98, the number of air flow paths 74 that can be shielded at one time can be set.

[0072] <4. Example of Scavenging Control Process> Next, an example of the scavenging control process executed by the control unit 50 will be described with reference to the flowchart shown in Figure 22. In the following description, the hydrogen gas flow path and the air supply flow path are not distinguished and are described as a gas flow path, and hydrogen gas and air are not distinguished and are described as scavenging gas.

[0073] First, the control unit 50 determines whether or not to start scavenging control (step S11). For example, the control unit 50 determines to start scavenging control when, for example, the fuel cell system 1 is stopped, when the temperature drops while the fuel cell system 1 is stopped, or when the fuel cell system 1 is started up. The timing to perform scavenging control is not limited to the above example, and scavenging control may be performed during a period when the charge capacity of the secondary battery is high and it is predicted that no power generation will be performed by the fuel cell 10. The control unit 50 repeats the determination in step S11 until it determines to start scavenging control.

[0074] When the control unit 50 determines to start scavenging control (S11 / Yes), it calculates the amount of residual water remaining in the gas flow path of the fuel cell 10 (step S13). The amount of residual water can be estimated, for example, based on the voltage during power generation after the previous execution of scavenging control and the temperature of the fuel cell 71. In this case, the amount of residual water in the gas flow path of each fuel cell 71 may be estimated based on the voltage and temperature for each fuel cell 71.

[0075] Next, the control unit 50 sets the position of the closing member according to the position, number, or area of the gas flow path to which the scavenging gas is supplied (step S15). For example, the greater the amount of residual water, the smaller the number or area of the gas flow path to which the scavenging gas is supplied may be, thereby increasing the flow rate of the scavenging gas. Alternatively, the scavenging gas may be supplied in descending order of the amount of residual water, or may be supplied sequentially from the end side. Furthermore, since the amount of residual water is more likely to increase as the outside temperature decreases, the position of the closing member may be set so that the number or area of the gas flow path to which the scavenging gas is supplied decreases as the outside temperature decreases. This increases the flow rate of the scavenging gas passing through the gas flow path, making it easier to discharge the residual water.

[0076] Next, the control unit 50 supplies scavenging gas to the gas flow path (step S17). For example, when supplying scavenging gas to the air flow path of the fuel cell 71, the back pressure regulating valve 17 is opened and the compressor 15 is driven to supply air to the fuel cell 10. Further, when supplying scavenging gas to the hydrogen gas flow path of the fuel cell 71, the purge valve 33 is closed and the circulation pump 25 is driven to supply hydrogen gas from the hydrogen supply source 21 to the fuel cell 10. As a result, the residual water in the gas flow path to which the scavenging gas is supplied is discharged to the outside of the fuel cell 10.

[0077] Next, the control unit 50 determines whether or not the scavenging time of the gas flow path currently supplied with the scavenging gas has elapsed the set time (step S19). For example, the scavenging time can be set based on the residual water amount and the flow velocity of the scavenging gas. However, instead of setting the scavenging time, the end time of scavenging of the gas flow path currently supplied with the scavenging gas may be determined based on the change in the differential pressure between the upstream pressure and the downstream pressure of the fuel cell 10 while the scavenging gas is being supplied. The control unit 50 repeats the determination in step S19 until the set time elapses.

[0078] When the set time has elapsed (S19 / Yes), the control unit 50 determines whether or not the scavenging of all the gas flow paths has been completed (step S21). If there is a gas flow path for which scavenging has not been completed (S21 / No), the control unit 50 returns to step S15, switches the position of the blocking member, and executes scavenging control. When the scavenging of all the gas flow paths has been completed (S21 / Yes), the control unit 50 stops the supply of the scavenging gas and terminates the scavenging control process (step S23).

[0079] As described above, according to the fuel cell system 1 according to the present embodiment, during power generation, when performing scavenging control without preventing power generation using all the fuel cells 71, the flow velocity of the scavenging gas supplied to the gas flow path can be increased. Therefore, the certainty of discharging the residual water in the gas flow path to the outside of the fuel cell 10 can be enhanced. At that time, by setting the number or area of the gas flow paths to which the scavenging gas is simultaneously supplied according to the amount of moisture remaining in each gas flow path and the outside air temperature, the residual water can be efficiently discharged.

[0080] As described above, the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the technology of the present disclosure is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present disclosure pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and these are also naturally understood to belong to the technical scope of the present disclosure.

[0081] For example, the shielding portion 80 according to the above embodiment is provided in the air supply manifold 75i and the hydrogen supply manifold 77i. However, the present disclosure is not limited to such examples. For example, the shielding portion may be provided in the air discharge manifold 75 o and the hydrogen discharge manifold 77 o or may be provided at an appropriate position where a part of the plurality of air flow paths 74 or the plurality of hydrogen gas flow paths 76 can be selectively shielded.

Explanation of Reference Numerals

[0082] 1... fuel cell system, 11... air supply flow path, 20... hydrogen supply flow path, 50... control unit, 71... fuel cell, 74... hydrogen gas flow path, 75i... air supply manifold (branch portion), 76... air flow path, 77i... oxygen supply manifold (branch portion), 80... shielding portion

Claims

1. A fuel cell including a plurality of fuel cells, A supply flow path for supplying gas to the plurality of fuel cells, A branch portion that branches the supply flow path into the gas flow paths of each of the plurality of fuel cells, A shielding portion provided in the branch portion that selectively shields each of the gas flow paths, A control unit that performs scavenging control to supply scavenging gas to the gas flow path to discharge moisture in the gas flow path, and includes: The shielding portion is rotationally controlled by the control unit and includes a closing member capable of supplying the gas or the scavenging gas to the gas flow path through an opening, The opening includes at least a first opening formed to have a size that can be opened without shielding all of the gas flow path, and a second opening provided at a position different from the first opening and formed to have a size that can be opened without shielding only one of the gas flow paths. And, The control unit controls the rotational position of the closing member to control the number of openings or the opening area of the gas flow path with respect to the opening, so that during power generation, the gas is supplied to all of the gas flow paths through the first opening, and during scavenging, the scavenging gas is supplied to the unshielded gas flow path through the second opening. A fuel cell system.

2. The fuel cell system according to claim 1, wherein the closing member is a hollow cylindrical member having the opening on the circumferential surface, or a belt-shaped member having the opening at different positions in the length direction.

3. The control unit sets the rotational position of the closing member so that the number of openings or the opening area of the gas flow path becomes smaller as the amount of moisture remaining in each of the gas flow paths is larger. The fuel cell system according to claim 1 or 2.

4. The control unit sets the rotational position of the closing member so that the number of openings or the opening area of the gas flow path becomes smaller as the outside air temperature is lower. The fuel cell system according to claim 1 or 2.

5. A discharge flow path for discharging the gas from the plurality of fuel cells, A confluence portion that combines the gas flow paths of each of the plurality of fuel cells and connects to the discharge flow path, and further includes: The fuel cell system according to any one of claims 1 to 4, wherein the shielding portion is provided in the confluence portion instead of the branch portion.

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