A fuel cell stack structure

Abstract

The present application relates to a kind of fuel cell stack structure, including stack core and the first current collector plate and the second current collector plate being closely arranged on the upper and lower surfaces of the stack core respectively, the stack structure further includes the disc spring end plate and the stack back end plate being sequentially arranged above the first current collector plate from bottom to top, disc spring is arranged in the disc spring end plate;When the stack back end plate is applied to the lower pressure, the stack back end plate applies the stack force to the stack spring, in turn, the stack force is applied to the stack core.Compared with prior art, the present application can solve the problem of uneven stress of stack core during compression, and solve the problem of end plate stress deformation caused by the original force applied to the end plate outside in prior art.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more particularly to a fuel cell stack structure. Background Technology

[0002] A proton exchange membrane fuel cell is a power generation device that directly converts the chemical energy present in fuel and oxidant into electrical energy.

[0003] In a typical proton exchange membrane fuel cell, the membrane electrode assembly (MEA) is generally placed between two conductive plates, each with a flow channel. These flow channels are formed on the surfaces in contact with the MEA through die casting, stamping, or mechanical milling, and there are usually more than one such channel. The single-plate assembly can be made of metal or graphite.

[0004] In a single-cell configuration of a proton exchange membrane fuel cell, there is only one membrane electrode assembly (MEA) and two monopolar plates. The two monopolar plates are located on opposite sides of the MEA: one is the anode monopolar plate for fuel, and the other is the cathode monopolar plate for oxidant. The antifreeze flow surfaces of both plates are bonded together to form a complete bipolar plate. This bipolar plate serves as both a current collector and a mechanical support for the MEA.

[0005] Existing fuel cell stacks consist of end plates, insulating plates, current collectors, and multiple individual cells. Multiple bipolar plates and membrane electrode assemblies are encapsulated together to form the core of the fuel cell stack. The core is wrapped inside by external support end plates, and the electrical energy generated by the chemical reaction is extracted through the current collectors at both ends of the inner core.

[0006] During the compression process, existing technologies apply the compression force to the end plates on the outside of the reactor stack. This compression method makes the end plates on the outside of the reactor stack the force-bearing surface, which can easily lead to deformation of the end plates under stress. This results in an unsatisfactory core compression bearing effect, which can easily cause uneven stress and off-center load. In severe cases, it can affect the airtightness of the core or even cause excessive local stress, leading to core collapse and rupture. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art and provide a fuel cell stack structure. This invention can solve the problem of uneven stress on the stack core during compression, and at the same time solve the problem of end plate deformation caused by the original force applied to the outer end plate of the stack in the prior art.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] This invention provides a fuel cell stack structure, including a stack core and a first current collector and a second current collector respectively closely disposed on the upper and lower surfaces of the stack core. The stack structure also includes a disc spring end plate and a stack rear end plate disposed sequentially above the first current collector from bottom to top, and the disc spring end plate is provided with a stack pressing disc spring.

[0010] When a downward pressure is applied to the rear end plate of the fuel cell stack, the rear end plate applies a pressure force to the pressure disc spring, thereby applying a pressure force to the fuel cell stack core.

[0011] Preferably, the disc spring end plate is provided with a disc spring mounting groove and a positioning groove for positioning the rear end plate of the fuel cell stack, and the stack disc spring is disposed in the disc spring mounting groove.

[0012] Preferably, the positioning groove has a circular cross-section, the disc spring mounting groove has an annular cross-section, and the positioning groove and the disc spring mounting groove are coaxially arranged.

[0013] Preferably, there are multiple stacked disc springs, and the multiple stacked disc springs are evenly distributed in the disc spring mounting groove along the center of the disc spring end plate.

[0014] Preferably, the rear end plate of the fuel cell stack includes an end plate positioning part, a disc spring compression part, and a pressing part integrally formed from bottom to top. The end plate positioning part, the disc spring compression part, and the pressing part 13 are all cylindrical and coaxially arranged. The cross-sectional area of ​​the end plate positioning part, the disc spring compression part, and the pressing part 13 increases sequentially.

[0015] When pressure is applied to the pressing part, the disc spring compression part compresses the stack disc spring provided in the disc spring mounting groove, thereby pressing the fuel cell stack core, and positioning it by the end plate positioning part extending into the positioning groove.

[0016] Preferably, the cross-sectional diameter of the disc spring compression section is smaller than the outer diameter of the cross-section of the disc spring mounting groove.

[0017] Preferably, the rear end plate and the front end plate of the fuel cell stack are provided with mounting portions on two opposite sides, and the two ends of the fuel cell stack locking rod are respectively fixed to the mounting portions of the rear end plate and the front end plate.

[0018] Preferably, when the bottom of the end plate positioning part contacts the bottom of the positioning groove, the downward pressure remains unchanged, the fuel cell stack locking rod is locked, and the downward pressure borne by the rear end plate of the fuel cell stack is transferred to the fuel cell stack locking rod.

[0019] Preferably, the depth of the positioning groove is determined according to the compression ratio of the stacked disc spring, and the specific process is as follows:

[0020] The load of the compression disc spring is determined, and the height corresponding to different compression amounts of the compression disc spring is obtained based on the load, thereby determining the depth of the positioning groove.

[0021] Preferably, the compression amount of the pressure disc spring is determined by measuring the distance between the bottom of the pressing part and the top of the disc spring end plate, thereby determining and controlling the magnitude of the downward pressure.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The fuel cell stack structure provided by the present invention provides a stacking disc spring by setting a stacking disc spring on the disc spring end plate, so that when a downward pressure is applied to the stack rear end plate, the stack rear end plate will directly act on the stacking disc spring, which solves the problem of deformation of the fuel cell stacking end plate under stress and the problem of fracture of a single bipolar plate due to stress in the prior art.

[0024] 2. The fuel cell stack structure provided by the present invention limits the depth of the disc spring mounting groove according to the compression rate of the stack disc spring, and during the continuous pressing of the press, when the end plate positioning part contacts the positioning groove, the compression deformation rate of the compression disc spring is limited, which can effectively ensure the airtightness of the stack core seal, while ensuring the consistency of the stack pressing force at each position of the stack core, and the deformation of the stack disc spring is controlled below 70%.

[0025] 3. The fuel cell stack structure provided by this invention employs a diagonal locking method to lock the stack locking rods while maintaining a constant stack compressive force. This allows the rear end plate of the stack to transfer the compressive force it bears to the surrounding stack locking rods, further ensuring the consistency of the stack compressive force at various locations within the stack core. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of a fuel cell stack structure provided by the present invention.

[0027] Figure 2 This is a schematic diagram of a fuel cell stack structure provided by the present invention.

[0028] The attached figures are labeled as follows: 1. Rear end plate of fuel cell stack; 11. End plate positioning part; 12. Disc spring compression part; 13. Pressing part; 2. Fuel cell stack locking rod; 31. First current collector plate; 32. Second current collector plate; 4. Front end plate of fuel cell stack; 5. Press disc spring; 6. Disc spring end plate; 61. Positioning groove; 62. Disc spring mounting groove; 7. Fuel cell stack core; 8. Bottom of press platform. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] This embodiment provides a fuel cell stack structure installed at the bottom 8 of a compressor platform. It includes a stack core 7, a first current collector 31 and a second current collector 32 respectively tightly disposed on the upper and lower surfaces of the stack core 7, and a disc spring end plate 6 and a stack front plate 4 respectively disposed above the first current collector 31 and below the second current collector 32. The disc spring end plate 6 has a positioning groove 61 and a disc spring mounting groove 62. A stack pressing disc spring 5 is disposed in the disc spring mounting groove 62. A stack rear end plate 1 is disposed above the disc spring end plate 6. The stack rear end plate 1 is positioned by the positioning groove 61. The stack rear end plate 1 presses the stack core 7 by compressing the stack pressing disc spring 5.

[0031] As an optional implementation, the positioning groove 61 has a circular cross-section, the disc spring mounting groove 62 has an annular cross-section, and the positioning groove 61 and the disc spring mounting groove 62 are coaxially arranged.

[0032] As an optional implementation, multiple stacked disc springs 5 ​​are provided, and the multiple stacked disc springs 5 ​​are evenly distributed in the disc spring mounting groove 62 along the center of the disc spring end plate 6.

[0033] As an optional implementation, the rear end plate 1 of the fuel cell stack includes an end plate positioning part 11, a disc spring compression part 12, and a pressing part 13 integrally formed from bottom to top. The end plate positioning part 11, the disc spring compression part 12, and the pressing part 13 are all cylindrical and coaxially arranged, and the cross-sectional area of ​​the end plate positioning part 11, the disc spring compression part 12, and the pressing part 13 increases sequentially.

[0034] The end plate positioning part 11 is inserted into the positioning groove 61 to achieve the positioning of the rear end plate 1 of the fuel cell stack. Under the action of the press, the disc spring compression part 12 compresses the stacking disc spring 5 provided in the disc spring mounting groove 62, thereby achieving the stacking of the fuel cell stack core 7.

[0035] Preferably, the cross-sectional diameter of the disc spring compression part 12 is smaller than the outer diameter of the cross-section of the disc spring mounting groove 62, so that when the disc spring compression part 12 compresses the disc spring 5, the pressing part 13 and the disc spring end plate 6 will not interfere with it.

[0036] Preferably, the depth of the positioning groove 61 is determined according to the compression ratio of the stacked disc spring 5, and the specific process is as follows:

[0037] The load of the compression disc spring 5 is determined. Based on the load, the height of the compression disc spring 5 corresponding to different compression amounts is obtained through experiments, and then the depth of the positioning groove 61 is determined.

[0038] The formula for calculating the load of the pressure-stabilized disc spring 5 is as follows:

[0039]

[0040] When f = h0, that is, when the disc spring is flat, the above equation simplifies to:

[0041]

[0042] In the formula, P is the load of a single disc spring, P C The calculated load of the disc spring under compression is given by: t is the thickness of the disc spring, D is the outer diameter of the disc spring, f is the deformation of a single disc spring, h0 is the calculated deformation of the disc spring under compression, E is the elastic modulus, μ is Poisson's ratio, and K1 and K4 are parameters.

[0043] Different pressure forces have different effects on the compression deformation rate of the pressure disc spring 5. In this embodiment, in order to ensure a pressure force of 36000N, the depth of the disc spring mounting groove 62 is designed to be 4mm.

[0044] Preferably, the compression amount of the stacking disc spring 5 is determined by measuring the distance between the bottom of the lower pressure section 13 and the top of the disc spring end plate 6, thereby determining a better control over the magnitude of the stacking force.

[0045] As an optional implementation, mounting portions are provided on both opposite sides of the fuel cell stack rear end plate 1 and the fuel cell stack front end plate 4, and the two ends of the fuel cell stack locking rod 2 are fixed to the mounting portions of the fuel cell stack rear end plate 1 and the fuel cell stack front end plate 4, respectively. In this embodiment, four fuel cell stack locking rods 2 are provided.

[0046] This embodiment provides a method for compressing a fuel cell stack structure as follows:

[0047] After all components of the fuel cell stack structure are installed, the press applies a pressing force of 25,000 N to 38,000 N to the pressing part 13, causing the disc spring compression part 12 to apply a pressing force to the pressing disc spring 5. Through continuous pressing, when the bottom of the end plate positioning part 11 contacts the bottom of the positioning groove 61, the press stops pressing, and the pressing force remains constant. At this point, the predetermined pressure has been reached, and the compression ratio of the fuel cell stack core 7's seal reaches the preset range of 15% to 35%, effectively ensuring the airtightness of the fuel cell stack core seal 7 and ensuring the consistency of the pressing force at various positions of the fuel cell stack core 7. Simultaneously, the deformation rate of the pressing disc spring 5 is controlled below 70%. At this point, with the pressing force remaining constant, the fuel cell stack locking rod 2 is locked using a diagonal locking method. The rear end plate 1 of the fuel cell stack transfers the pressing force it bears to the surrounding pressing rods 2, further ensuring the consistency of the pressing force at various positions of the fuel cell stack core 7.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A fuel cell stack structure, comprising a stack core (7) and a first current collector (31) and a second current collector (32) respectively tightly disposed on the upper and lower surfaces of the stack core (7), characterized in that, The fuel cell stack structure also includes a disc spring end plate (6) and a fuel cell stack rear end plate (1) arranged sequentially above the first current collector (31) from bottom to top. The disc spring end plate (6) is provided with a stacking disc spring (5). When a downward pressure is applied to the rear end plate (1) of the fuel cell stack, the rear end plate (1) applies a pressure force to the pressure disc spring (5), and then applies a pressure force to the fuel cell stack core (7); The disc spring end plate (6) is provided with a disc spring mounting groove (62) and a positioning groove (61) for positioning the rear end plate (1) of the fuel cell stack. The stack disc spring (5) is located in the disc spring mounting groove (62). The positioning groove (61) has a circular cross-section, the disc spring mounting groove (62) has an annular cross-section, and the positioning groove (61) and the disc spring mounting groove (62) are coaxially arranged. Multiple stacked disc springs (5) are provided, and the multiple stacked disc springs (5) are evenly distributed in the disc spring mounting groove (62) along the center of the disc spring end plate (6); The rear end plate (1) of the fuel cell stack includes an end plate positioning part (11), a disc spring compression part (12) and a pressing part (13) integrally formed from bottom to top. The end plate positioning part (11), the disc spring compression part (12) and the pressing part (13) are all cylindrical and coaxially arranged. The cross-sectional area of ​​the end plate positioning part (11), the disc spring compression part (12) and the pressing part (13) increases sequentially. When the pressing part (13) is pressured, the disc spring compression part (12) compresses the stacking disc spring (5) provided in the disc spring mounting groove (62), thereby pressing the stack core (7) and positioning it by extending the end plate positioning part (11) into the positioning groove (61); The cross-sectional diameter of the disc spring compression part (12) is smaller than the cross-sectional outer diameter of the disc spring mounting groove (62); The depth of the positioning groove (61) is determined according to the compression ratio of the stacked disc spring (5), and the specific process is as follows: The load of the pressurized disc spring (5) is determined, and the height corresponding to different compression amounts of the pressurized disc spring (5) is obtained based on the load, thereby determining the depth of the positioning groove (61).

2. The fuel cell stack structure according to claim 1, characterized in that, The rear end plate (1) and the front end plate (4) of the fuel cell stack are provided with mounting parts on their two opposite sides. The two ends of the fuel cell stack locking rod (2) are fixed to the mounting parts of the rear end plate (1) and the front end plate (4) of the fuel cell stack, respectively.

3. The fuel cell stack structure according to claim 2, characterized in that, When the bottom of the end plate positioning part (11) contacts the bottom of the positioning groove (61), the downward pressure remains unchanged, the fuel cell locking rod (2) is locked, and the downward pressure borne by the fuel cell rear end plate (1) is transferred to the fuel cell locking rod (2).

4. The fuel cell stack structure according to claim 1, characterized in that, By measuring the distance between the bottom of the pressing part (13) and the top of the disc spring end plate (6), the compression amount of the press disc spring (5) is determined, and the magnitude of the pressing force is determined and controlled.

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