CN107808974B

CN107808974B - Device for improving compression uniformity of bolt packaged fuel cell assembly

Info

Publication number: CN107808974B
Application number: CN201710990012.7A
Authority: CN
Inventors: 吴承伟; 刘行; 刘博�; 陈雪松; 张伟; 熊月娇; 王佳庆
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2017-10-23
Filing date: 2017-10-23
Publication date: 2020-04-28
Anticipated expiration: 2037-10-23
Also published as: CN107808974A

Abstract

The invention belongs to the technical field of fuel cell stack packaging, and provides a device for improving the compression uniformity of a bolt packaged fuel cell assembly, wherein the packaged thin-shell device is assembled between an end plate and a bolt, the section shape of the packaged thin-shell device is in an arch shape, and the bending direction of the packaged thin-shell device is opposite to the bending deformation direction of the end plate; the outer edge region of the device has a parallel gap with the outer edge of the end plate before applying the sealing force, and a sealing gasket is arranged in the gap for preventing looseness and ensuring the close fit of the device and the end plate. The device reduces the bending deformation of the end plate towards its outer edge under the action of the sealing force. The whole device can be simply installed on the fuel cell, and the compression uniformity of the internal components of the cell is effectively improved, so that the safety and stability of service of the cell are improved.

Description

Device for improving compression uniformity of bolt packaged fuel cell assembly

Technical Field

The invention belongs to the technical field of fuel cell stack packaging, and relates to a structural design of a device for improving the pressure uniformity of a bolt packaged fuel cell assembly.

Background

The Proton Exchange Membrane Fuel Cell (hereinafter abbreviated as PEMFC) stack is composed of multi-stage single cells, and the common packaging methods include bolt packaging and steel strip packaging. For bolted cell stacks, the end plates and bolts are the packaging components that apply the packaging force. The structure of the end plate, the number and distribution form of bolts, the applied bolt tightening torque and the like need to be reasonably designed to ensure that components such as Membrane Electrode Assemblies (MEA) and sealing elements are uniformly compressed after being packaged, so that negative phenomena such as local stress concentration and poor contact among the components are effectively prevented. The sealing force applied by the bolts can cause the end plates to flex toward the outer edges, which is particularly the case in large automotive stacks. This situation can lead to an uneven distribution of pressure transmitted through the end plate structure to the cell's internal components: larger at the seal and outer edge of the MEA, but smaller in the central region of the MEA. In more serious cases, the sealing member may be locally damaged by the excessive pressure in the partial region, and the uneven pressure of the MEA may cause problems such as local increase of contact resistance, inhibition of mass transfer, and local temperature increase (formation of hot spot region), thereby affecting the operation performance of the PEMFC. Therefore, in order to ensure stable and efficient operation of the cell during service, it is necessary to reduce the bending deformation of the end plate under the action of the sealing force, so as to improve the pressure environment of the MEA and the sealing member and realize uniform pressure.

Disclosure of Invention

In view of the problems of the prior art, the present invention provides a packaged thin shell device.

The technical scheme of the invention is as follows:

an apparatus for improving the uniformity of compression of a bolt-on-fuel cell assembly is an encapsulated thin shell device 1. Under the action of the packaging force, the device can effectively reduce the bending deformation of the end plate towards the outer edge of the end plate, so that the compression uniformity inside the battery is improved, and the applied bolt torque is the packaging force. The packaging thin-shell device 1 is made of aluminum alloy metal through stamping, the size of the packaging thin-shell device is determined according to the compression condition, the impedance and the air tightness of a single cell assembly in the process of applying bolt torque to the fuel cell assembly, and the thickness of the packaging thin-shell device is preferably 2 mm.

The thin-shell packaging device 1 is assembled between an end plate 3 and a bolt 4, the cross section size of the thin-shell packaging device is consistent with that of the end plate 3, the cross section shape of the thin-shell packaging device is arched, and the bending direction of the thin-shell packaging device is opposite to that of the end plate. The central area of the device is inwards concave towards the end plate 3, the inwards concave area 11 is contacted with the middle area of the end plate 3 before bolt torque is applied, a parallel gap is formed between the outer edge area 12 of the device and the outer edge of the end plate 3 before packaging force is applied, and a packaging gasket 2 is arranged in the gap and used for preventing looseness and ensuring the close fit of the device and the end plate; between the peripheral region 12 and the concave region 11 is a curved transition region 13.

The bolts 4 are rotated and a bolt torque is applied, during which the bending deformation of the encapsulating shell device 1 increases and the curved transition zone 13 and the concave zone 11 are both bent in the direction opposite to the bending direction of the shell, while the peripheral zone 12 is pressed against the end plate in contact with the encapsulating gasket 2, and the encapsulating force is transmitted via the gasket 2 to the peripheral zone of the end plate 3. The other end of the end plate 3 is sequentially provided with an insulating plate 5 and a current collecting plate 6, each single cell 10 is arranged between the two current collecting plates 6, each single cell forms a compact integral structure under the action of packaging force by means of friction force between components, and each single cell consists of a bipolar plate 7, a membrane electrode 8 and a sealing element 9. Concentric circular bolt holes are formed in the outer edge region 12 of the packaging thin-shell device 1, and the edges of the packaging gasket 2, the end plate 3, the insulating plate 5 and the current collecting plate 6 are used for assembling the bolts 4 to pass through so as to assemble all the components together; the positions and sizes of the circular bolt holes are determined according to the bolt holes on the single cells 10.

The thickness of the packaging washer 2 is slightly smaller than the gap size, and a circular bolt hole for assembling a bolt is also machined.

The use process of the device is as follows:

1) the fuel cell components are first assembled.

2) The recessed area 11 is in contact with the middle area of the end plate 3 before the bolt torque is applied; gradually increasing the applied bolt torque, and transmitting the packaging force to the central area of the end plate 3 through the concave area 11 of the packaging thin-shell device; as the bolt torque increases, the bending deformation of the encapsulating thin-shell device 1 increases, its peripheral area 13 comes into contact with the encapsulating washer 2, and the encapsulating force is transmitted through the washer 2 to the peripheral area of the end plate 3. Therefore, more packaging force can be transmitted to the central area of the end plate through the packaging thin shell, and the end plate can be prevented from being bent and deformed greatly towards the outer edge under the action of the packaging force applied by the outer edge bolt.

3) The bolt torque was adjusted to the final design value. The assembly of the encapsulating thin-shell device 1, the encapsulating washer 2, the end plate 3 and the bolt 4 is checked for fit. The internal cell assembly was tested for compression and for characteristics such as impedance and gas tightness of the battery. If the battery has problems or abnormalities in the detection and the assembly operation is confirmed to be correct, the structural design size of the packaging thin-shell device needs to be changed and adjusted, and the processes 1) and 2) are repeated. And if the detection is qualified, finishing the packaging and assembling process of the battery.

The invention has the beneficial effects that: firstly, from the manufacturing point of view, the processing cost is relatively low, and the uniformity of the compression inside the battery can be simply and effectively improved. And secondly, for the fuel cell which is processed and formed, if the problem that the components are not uniformly pressed exists, the problem can be improved by additionally installing the device without greatly changing the original design structure.

Drawings

Fig. 1 is a schematic diagram of the structure of a fuel cell 1/8.

Fig. 2 is a schematic structural diagram of the packaging thin-shell device 1/4.

Figure 3 is a cross-sectional view of a fuel cell assembly having an encapsulated thin shell device according to the present invention.

Fig. 4 is a schematic cross-sectional view of a fuel cell assembly of a conventional non-encapsulated thin-shell device.

In the figure: 1 packaging the thin-shell device; 2, packaging a gasket; 3, end plates; 4, bolts; 5, insulating plates; 6 a collector plate; 7 a bipolar plate; 8 Membrane Electrode Assembly (MEA); 9 a seal member; 10 single cells; 11 a recessed area; 12 a peripheral edge region; 13 bending the transition region.

Detailed Description

Taking a certain model of proton exchange membrane fuel cell product as an example, the specific implementation mode of the invention is as follows:

1) the fuel cell modules are placed in the positional relationship shown in fig. 1, and the package sheet means 1 is located between the end plate 3 and the bolts 4. The recessed region 11 of the device contacts the middle region of the end plate before the bolt torque is applied and the peripheral region 12 of the device has a parallel gap with the outer edge of the end plate in which the packing washer is mounted. The concentric holes of the thin shell device 1, the packing washer 2, the end plate 3, the insulating plate 5 and the current collecting plate 6 are ensured, and the bolts 4 are inserted into the holes. Between the two current collector plates are individual cells 10 which form a tight integral structure under the sealing force by virtue of the friction between the components. Each unit cell is composed of a bipolar plate 7, an MEA 8, and a seal member 9.

2) As shown in fig. 3, with increasing applied bolt torque, the potting force is first transmitted through the recessed area 11 of the potting shell arrangement to the central area of the end plate 3. As the bolt torque increases, the bending deformation of the encapsulating thin-shell device 1 increases, its peripheral area 13 comes into contact with the encapsulating washer 2, and the encapsulating force is transmitted through the washer 2 to the peripheral area of the end plate 3. Therefore, more packaging force can be transmitted to the central area of the end plate through the packaging thin shell, and the end plate can be prevented from being bent and deformed greatly towards the outer edge under the action of the packaging force applied by the outer edge bolt.

The cross section of the device of the invention is in a bow shape, and the bending direction of the device is opposite to the bending deformation direction of the end plate. Thus, the amount of bending deformation of the end plate under the sealing force is reduced. For the type of fuel cell product listed, after installation of the encapsulated thin shell device, the pressure in the central region of the MEA rises significantly, while the pressure in the peripheral region and on the seal decreases accordingly. The uniformity of the distribution of the contact pressure of the MEA with the seal member as a whole is improved. And the added packaging thin-shell device does not excessively increase the weight of the whole battery.

The embodiments of the invention should be considered in all respects as illustrative and not restrictive examples, applicable to other plate fuel cell stacks of similar construction. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A device for improving the compression uniformity of a bolt packaged fuel cell assembly is characterized in that the device is a packaged thin-shell device (1), and can effectively reduce the bending deformation of an end plate (3) towards the outer edge of the end plate and improve the compression uniformity in a cell; the size of the packaging thin-shell device (1) is determined according to the compression condition, the impedance and the airtight characteristic of the single cell assembly in the process of applying bolt torque to the fuel cell assembly;

the packaging thin-shell device (1) is assembled between the end plate (3) and the bolt (4), and the cross section sizes of the packaging thin-shell device (1) and the end plate (3) are consistent; the central area of the device is inwards concave towards the end plate (3), the inwards concave area (11) is contacted with the middle area of the end plate (3) before bolt torque is applied, a parallel gap is formed between the outer edge area (12) of the device and the outer edge of the end plate (3) before packaging force is applied, and a packaging gasket (2) is installed in the gap and used for preventing looseness and ensuring the close fit of the device and the end plate; rotating the bolt (4) to apply bolt torque, in the process, the bending deformation of the packaging thin shell device (1) is increased, the bending transition area (13) and the concave area (11) are bent towards the direction opposite to the bending direction of the thin shell, meanwhile, the outer edge area (12) is pressed towards the end plate and is contacted with the packaging gasket (2), and the packaging force is transmitted to the outer edge area of the end plate (3) through the packaging gasket (2); the other end of the end plate (3) is sequentially provided with an insulating plate (5) and a collector plate (6), and each single cell (10) is arranged between the two collector plates (6); concentric circular bolt holes are formed in the edge region (12) of the packaging thin-shell device (1), the edges of the packaging gasket (2), the end plate (3), the insulating plate (5) and the current collecting plate (6) and used for assembling bolts (4) and assembling all the parts together; the positions and the sizes of the circular bolt holes are determined according to the bolt holes on the single cells (10).

2. The device for improving the compression uniformity of a bolt-packaged fuel cell assembly according to claim 1, wherein said packaging thin-shell device (1) is made by stamping aluminum alloy metal.

3. The device for improving the compression uniformity of a bolt-packaged fuel cell assembly according to claim 2, wherein the thickness of the packaging thin shell device (1) is 2 mm.

4. An arrangement for improving the compression uniformity of a bolt-on fuel cell assembly according to claim 1 or 2, characterized in that the thickness of the packing washer (2) is smaller than the gap dimension and is also machined with circular bolt holes for bolts to fit through.