Apparatus for manufacturing fuel cell stack

Abstract

To provide an apparatus for manufacturing a fuel cell stack that can be fastened with an appropriate load for each fuel cell stack.SOLUTION: An apparatus 1 for manufacturing a fuel cell stack 10 includes: pressurizing means 72 capable of pressurizing the fuel cell stack 10 before fastening, along a stacking direction 101; overall load detection means 74 that, when the pressurizing means 72 pressurizes, detects a load of the fuel cell stack 10; and calculation means 79 that calculates a load per unit time for a load detected by the overall load detection means 74. The pressurizing means 72 stops pressurizing in a case where the load per unit time calculated by the calculation means 79 is equal to or greater than a first predetermined value.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a manufacturing apparatus for a fuel cell stack including a laminate in which a plurality of power generation cells are stacked.

Background Art

[0002] A polymer electrolyte fuel cell includes an electrolyte membrane / electrode structure (MEA). Electrodes are provided on both sides of the polymer electrolyte membrane of the electrolyte membrane / electrode structure. A seal member is provided on the outer periphery of the electrolyte membrane / electrode structure. The seal member is a member for preventing leakage of fuel gas, refrigerant, and the like. The electrolyte membrane / electrode structure is sandwiched between separators to constitute a power generation cell. A required number of power generation cells are stacked to form a laminate in order to obtain a desired voltage. The laminate is used in the form of a fuel cell stack to which an end plate or the like is attached.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the manufacturing process of the fuel cell stack includes a stack fastening operation. The stack fastening operation includes, for example, pushing a lid into a stack case and seating it, and screwing the lid to the stack case. In such a stack fastening operation, conventionally, the pressurizing operation of the lid to the stack case is stopped based on the height of the lid after pushing, the pushing amount of the lid, or the magnitude of the load when pushing the lid.

[0005] The thicknesses of the components that make up the fuel cell stack may include variations. Therefore, even when the pressurization operation is stopped under the same conditions, the load received by the stack case may be different. That is, in the conventional stack fastening operation, it is difficult to control the load received by the stack case when the lid seats on the stack case.

[0006] Therefore, an object of the present invention is to provide a manufacturing apparatus for a fuel cell stack that can fasten each fuel cell stack with an appropriate load.

Means for Solving the Problems

[0007] The manufacturing apparatus for a fuel cell stack of the present invention is a manufacturing apparatus for a fuel cell stack for manufacturing a fuel cell stack, and includes a pressurizing means capable of pressurizing the fuel cell stack before fastening along the stacking direction, an overall load detecting means for detecting the load of the fuel cell stack when pressurized by the pressurizing means, and a calculating means for calculating the load per unit time for the load detected by the overall load detecting means. The pressurizing means stops pressurization when the load per unit time calculated by the calculating means becomes equal to or greater than a first predetermined value.

[0008] According to the above-described manufacturing apparatus for a fuel cell stack, it is possible to provide a manufacturing apparatus for a fuel cell stack that can fasten each fuel cell stack with an appropriate load.

[0009] The calculating means calculates the rate of change of the load per unit time, and the first predetermined value can be set to a value equal to or greater than the value of the load per unit time when the rate of change becomes a second predetermined value.

[0010] According to the above-described manufacturing apparatus for a fuel cell stack, the first predetermined value can be appropriately determined.

[0011] The fuel cell stack includes a stack case, and the first predetermined value is a value equal to or greater than the value of the load per unit time when the rate of change becomes the second predetermined value, and can be set to a value less than the value of the load per unit time when the limit load of the stack case is applied to the stack case.

[0012] According to the manufacturing apparatus of the fuel cell stack described above, it is possible to perform fastening with sufficient strength without applying a load exceeding the limit to the stack case.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a manufacturing apparatus for a fuel cell stack that can fasten each fuel cell stack with an appropriate load.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0015] (Fuel Cell Stack) A manufacturing apparatus 1 for a fuel cell stack 10 according to an embodiment of the present invention will be described. Before describing the manufacturing apparatus 1, the fuel cell stack 10 will be described. FIG. 1 is a perspective view of the fuel cell stack 10 according to the present embodiment. The fuel cell stack 10 includes a laminate 14. The laminate 14 includes a plurality of stacked power generation cells 12.

[0016] (Power Generation Cell and Stack) The power generation cell 12 has a structure in which an electrolyte membrane / electrode structure is sandwiched between conductive separators. A resin frame member is provided around the electrolyte membrane / electrode structure. Also, a seal member is provided at the outer peripheral end of the separator. The seal member is formed of a material having elasticity such as rubber. A stack 14 is formed by laminating a plurality of power generation cells 12. The stack 14 includes an electrode stack portion and a seal stack portion. The electrode stack portion is mainly the portion where the electrolyte membrane / electrode structures are laminated. The seal stack portion is the portion where the seal members are laminated.

[0017] FIG. 1 shows a first direction 101, a second direction 102, and a third direction 103. The first direction 101, the second direction 102, and the third direction 103 are orthogonal to each other. The first direction 101 is the direction in which the power generation cells 12 are laminated. The first direction 101 is referred to as the lamination direction 101.

[0018] At one end of the stack 14 in the lamination direction 101, a first insulator 18 and a first end plate 21 are arranged in this order toward the outside of the stack 14. At the other end of the stack 14 in the lamination direction 101, a second insulator 19 and a second end plate 22 are arranged in this order toward the outside of the stack 14. The material of the insulator is, for example, an insulating material such as polycarbonate and phenolic resin. A spacer may be arranged between the stack 14 and the end plate.

[0019] As shown in FIG. 1, the shape of the end plate is rectangular. A connecting bar 24 is arranged between the opposing sides of the first end plate 21 and the second end plate 22. Both ends of the connecting bar 24 are fixed to each end plate with bolts 26. By fixing both end plates via the connecting bar 24, the distance between the first end plate 21 and the second end plate 22 is fixed. Also, a fastening load in the lamination direction 101 is applied to each power generation cell 12.

[0020] FIG. 1 shows a fuel cell stack 10 fastened using a first end plate 21, a second end plate 22, and a connecting bar 24. The configuration of the fuel cell stack 10 is not limited to the configuration of FIG. 1. For example, the fuel cell stack 10 may be fastened using a stack case and a lid.

[0021] (Manufacturing apparatus for fuel cell stack) Referring to FIGS. 2A and 2B, a manufacturing apparatus 1 for the fuel cell stack 10 will be described. FIGS. 2A and 2B are diagrams showing the manufacturing apparatus 1 for the fuel cell stack 10 of the present embodiment. FIG. 2A shows the manufacturing apparatus 1 for the fuel cell stack 10 before seating. FIG. 2B shows the manufacturing apparatus 1 for the fuel cell stack 10 in a seated state.

[0022] As shown in FIGS. 2A and 2B, the manufacturing apparatus 1 for the fuel cell stack 10 mainly includes a pressurizing means 72, an overall load detecting means 74, a control unit 78, a pressure plate 81, a fixing member 60, and a holding table 80. As shown in FIGS. 2A and 2B, in the stacking direction 101, the direction indicated by the arrow 104 is defined as the upward direction 104. In the stacking direction 101, the direction indicated by the arrow 105 is defined as the downward direction 105. The holding table 80 is disposed in the downward direction 105 in the manufacturing apparatus 1. The pressure plate 81 is disposed in the upward direction 104 in the manufacturing apparatus 1. A laminate 14 as a part of the object to be pressurized is installed between the holding table 80 and the pressure plate 81. The object to be pressurized refers to an object that is disposed between the holding table 80 and the pressure plate 81 and is pressurized by the pressure plate 81.

[0023] (Pressurizing means) The pressurizing means 72 pressurizes the object to be pressurized in the downward direction 105 by bringing the pressure plate 81 closer to the holding table 80. The downward direction 105 is referred to as the pressurizing direction. The pressurizing means 72 can apply a load to the object to be pressurized. The pressurizing means 72 is, for example, a press mechanism such as a servo press.

[0024] (Pressure plate) The pressure plate 81 is a part that applies a load to the object to be pressed by being pressed by the pressing means 72. A fixing member 60 is disposed between the pressure plate 81 and the object to be pressed. The holding base 80 is a part where an object to be pressed such as the fuel cell stack 10 is installed.

[0025] The overall load detection means 74 is a means for detecting the overall load applied to the entire object to be pressed. The entirety of the object to be pressed includes the electrode laminate and the seal laminate. The overall load detection means 74 is constituted by, for example, a load cell. The overall load detection means 74 detects the load applied to the pressure plate 81 pressed against the object to be pressed, and outputs the detection result to the control unit 78.

[0026] (Control unit) The control unit 78 is a part that controls the operation of the manufacturing apparatus 1. The control unit 78 controls the pressing means 72, and adjusts the force for pressing the pressure plate 81, the speed for moving the pressure plate 81, the timing for stopping the pressure plate 81, and the like. The load detected by the overall load detection means 74 is input to the control unit 78. The control unit 78 includes a calculation means 79. The calculation means 79 calculates the load per unit time for the load detected by the overall load detection means 74. Further, the calculation means 79 calculates the rate of change of the load per unit time. When the load per unit time calculated by the calculation means 79 or the rate of change of the load per unit time calculated reaches a predetermined value or more, the control unit 78 can stop the pressing of the pressure plate 81 by the pressing means 72.

[0027] (Stack fastening operation) With reference to FIGS. 2A and 2B, the stack fastening operation will be specifically described. FIGS. 2A and 2B show an example in which the lid 27 is brought into contact with the stack case 25 from above. The contact of the lid 27 with the stack case 25 is referred to as seating.

[0028] FIG. 2A shows the state before seating in the stack fastening operation. In the stack fastening operation, the pressure plate 81 is moved by the pressing means 72 in the direction of arrow A1. The direction of arrow A1 is a direction parallel to the downward direction 105.

[0029] (Seating) Figure 2B shows the state after seating in the stack fastening operation. When the pressure plate 81 is further pushed in the direction of arrow A1, as shown in Figure 2B, the lid 27 seats on the stack case 25. Arrow A2 in Figure 2B indicates the portion where the lid 27 seats on the stack case 25.

[0030] (Screwing) In the stack fastening operation, after the lid 27 seats on the stack case 25, the lid 27 is screwed to the stack case 25 using screws such as the bolt 26 shown in Figure 1 above.

[0031] (Limit load) Here, there may be a case where the load that can be applied to the stack case after seating is restricted. This load is called the limit load. The pressurizing operation on the lid 27 via the pressure plate 81 by the pressurizing means 72 needs to be performed within the range where the lid 27 seats on the stack case 25 and a load exceeding the limit load is not applied to the stack case 25.

[0032] Conventionally, the stop of the pressurizing operation on the lid 27 has been performed based on the position of the lid 27 in the stacking direction 101, or the load applied to the lid 27, etc. Therefore, due to the influence of variations in the thickness of the members included in the laminate 14 or the parts involved in stack fastening, it is difficult to control the load applied to the stack case 25 during seating.

[0033] In the manufacturing apparatus 1 of the present embodiment, by using the contact load detection stop function, even when there are variations in the thickness of the parts, the load applied to the stack case 25 can be made constant and the stack fastening operation can be performed.

[0034] (Contact load detection stop function) Referring to FIG. 3, the contact load detection stop function will be described. FIG. 3 is a diagram for explaining the outline of determining the timing of stopping the pressurization by contact load detection. The X-axis in FIG. 3 indicates the time T from the start of the pressurization operation. The Y-axis in FIG. 3 indicates the load per unit time, that is, W / T.

[0035] In the manufacturing apparatus 1 of the present embodiment, the timing for stopping the pressurization operation of the pressurizing means 72 is determined by the load per unit time. The load per unit time when stopping the pressurization operation is defined as the threshold value TH. As shown in FIG. 3, the value of the threshold value TH is determined in advance. The value of the threshold value TH determined in advance is referred to as the first predetermined value. Then, when the load per unit time reaches the threshold value TH, the pressurization operation is stopped. In FIG. 3, the point where the load per unit time reaches the threshold value TH is shown as point P1.

[0036] As shown in FIG. 3, by determining the timing of stopping the pressurization by the load per unit time, a load exceeding the limit load is not applied to the stack case 25, and each fuel cell stack 10 can be fastened with an optimal load.

[0037] (Method for obtaining the load per unit time) The load per unit time (W / T) can be obtained as follows. While the pressurizing means 72 is pressurizing the pressure plate 81 under a predetermined condition, for example, at a constant speed, the overall load detection means 74 detects the entire load applied to the lid 27 or the like. The load applied to the pressure plate 81 detected by the overall load detection means 74 is input to the control unit 78. The control unit 78 includes a calculation means 79. The calculation means 79 calculates the load per unit time. In this way, the load per unit time can be obtained. Further, the control unit 78 may calculate the rate of change of the load per unit time.

[0038] (Method for obtaining the threshold value) Referring to FIG. 4, the method of determining the threshold value TH will be described. FIG. 4 is a diagram showing the relationship between the stack length of the fuel cell stack and the load per unit time applied to the fuel cell stack by the pressurizing means. The X-axis in FIG. 4 indicates the stack length [mm] of the fuel cell stack. The Y-axis in FIG. 4 indicates the load W [kN / 0.1 sec (seconds)] per unit time applied to the fuel cell stack. The load per unit time applied to the fuel cell stack is recorded every 0.1 seconds. Note that the numerical values on the Y-axis in FIG. 4 are for illustration purposes. The value of the load per unit time applied to the fuel cell stack varies depending on the configuration of the fuel cell stack and the like.

[0039] Arrow A10 in FIG. 4 indicates the direction of change in the stack length L of the fuel cell stack 10 when the pressurization of the fuel cell stack 10 by the pressurizing means 72 progresses. The direction indicated by arrow A10 is referred to as the pressurization direction A10. In the graph of FIG. 4, the X-axis is sequentially divided into a first region R1, a second region R2, and a third region R3 in the pressurization direction A10.

[0040] (First region) The first region R1 is the region from the start of pressurization to line L1 in FIG. 4. The first region R1 is a region where the stack length L of the power generation cells 12 mainly decreases due to compression. In the first region R1, the load per unit time is approximately constant. In the example shown in FIG. 4, the load per unit time is approximately constant at about 1.5 kN / second.

[0041] (Second region) The second region R2 is the region from line L1 to line L2 in FIG. 4. The second region R2 is a region where, due to compression, in addition to the power generation cells 12, the stack length L of the packing (not shown) disposed between the stack case 25 and the lid 27 decreases. This packing is disposed to suppress leakage of hydrogen and the like. In the second region R2, the load per unit time gradually increases as the stack length L decreases. The reason why the tendency of the change in the load per unit time is different between the first region R1 and the second region R2 is that compression of the packing occurs in the second region R2. In the second region R2, the load per unit time increases up to approximately 0.5 kN / second.

[0042] (Third region) The third region R3 is the region from the line L2 in FIG. 4 to the stop of pressurization. The third region R3 is the region from when the lid 27 is seated on the stack case 25 until the pressurization stops. P10 in FIG. 4 indicates the time of seating. P11 indicates the time of stopping pressurization. In the third region R3, the stacking length L does not decrease much. This is because the stack case 25 and the lid 27 are less compressible than the power generation cell 12 etc. Also, in the third region R3, the load per unit time rises steeply. This is because in the third region R3, the load is applied not to the power generation cell 12 etc., but to the stack case 25 and the lid 27 which are less likely to shrink.

[0043] (Overshoot) The pressurization between the seating P10 and the stop of pressurization P11 is called overshoot. The load applied during overshoot becomes the case load. The case load is the load applied to the stack case 25. The arrow A11 in FIG. 4 indicates the case load. For example, if the load at the time of seating P10 is 46.6 kN and the load at the time of stopping pressurization P11 is 51.3 kN, the case load is the difference, 4.7 kN.

[0044] In the manufacturing apparatus 1 of the present embodiment, when the value of the load per unit time reaches a predetermined value (threshold value), the pressurization is stopped. The threshold value is preferably the value at the time when a predetermined pressurization is performed after seating. Thereby, for example, even when there are thickness variations in the components included in the fuel cell stack 10, it is possible to suppress the fastening from becoming insufficient. In the example shown in FIG. 4, the threshold value is preferably set to a value of 0.5 kN / 0.1 second or more of the load per unit time at the seating P10.

[0045] Also, as described above, the load that may be applied to the stack case 25 after seating may be restricted (restricted load). The threshold value is preferably set to a value such that the load exceeding the restricted load is not applied to the stack case 25 due to overshoot. In the example shown in FIG. 4, when the restricted load of the stack case 25 is 10 kN, the point in time when the load applied to the stack case 25 becomes 4.7 kN is defined as the pressurization stop P11. In this case, the load per unit time as the threshold value is set to a value slightly exceeding 1.4 kN / 0.1 second.

[0046] The load per unit time at the time of seating can be determined by the change in the load per unit time. As shown in FIG. 4, the load per unit time rises steeply after seating P10. Therefore, the position where the load per unit time starts to change at a slope of 0.1 kN / 0.1 sec or more (second predetermined value) can be defined as the position where seating P10 has occurred.

[0047] Note that the present invention is not particularly limited to the above-described embodiments, and various modifications are possible without departing from the gist thereof.

Explanation of Reference Numerals

[0048] 1 Manufacturing apparatus 10 Fuel cell stack 12 Power generation cell 14 Laminate 18 First insulator 19 Second insulator 21 First end plate 22 Second end plate 24 Connecting bar 25 Stack case 26 Bolt 27 Lid 60 Fixing member 72 Pressurizing means 74 Total load detecting means 78 Control unit 79 Calculating means 80 Holding table 81 Pressurizing plate 101 First direction, lamination direction 102 Second direction 103 Third direction A10 Pressing direction R1 First region R2 Second region R3 Third region P10 Seating P11 Pressure stop

Claims

1. A fuel cell stack manufacturing apparatus for manufacturing a fuel cell stack, comprising: pressing means capable of pressing the fuel cell stack before fastening along the stacking direction; overall load detection means for detecting the load of the fuel cell stack when pressed by the pressing means; calculating means for calculating the load per unit time for the load detected by the overall load detection means; and the pressing means stops pressing when the load per unit time calculated by the calculating means becomes equal to or greater than a first predetermined value. A fuel cell stack manufacturing apparatus.

2. The calculating means calculates a rate of change of the load per unit time, wherein the first predetermined value is a value equal to or greater than the value of the load per unit time when the rate of change becomes a second predetermined value. The fuel cell stack manufacturing apparatus according to claim 1.

3. The fuel cell stack includes a stack case, wherein the first predetermined value is a value equal to or greater than the value of the load per unit time when the rate of change becomes a second predetermined value and less than the value of the load per unit time when the limit load of the stack case is applied to the stack case. The fuel cell stack manufacturing apparatus according to claim 2.

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