WO2011098276A1

WO2011098276A1 - Fuel cell arrangement and method for the production thereof

Info

Publication number: WO2011098276A1
Application number: PCT/EP2011/000629
Authority: WO
Inventors: Holger Stark
Original assignee: Daimler Ag
Priority date: 2010-02-15
Filing date: 2011-02-10
Publication date: 2011-08-18
Also published as: DE102010007981A1

Abstract

The invention relates to a fuel cell arrangement comprising an upper end plate (12), a lower end plate (13), a plurality of fuel cells (11) that are stacked between the upper end plate (12) and the lower end plate (13), at least one tensioning means (16) that acts between the upper end plate (12) and the lower end plate (13) for carrying out a tensile force between the upper end plate (12) and the lower end plate (13) along a tensioning direction, and a fixing element (31) for a mechanical coupling between the tensioning means (16) and at least one of the end plates (12, 13) and/or between two tensioning means (16). The fuel cell arrangement also comprises a coupling region in which the tensioning means (16) and the fixing element (17) are connected to each other. According to the invention, the fixing element (17) is designed as an eccentric element (20, 25, 31, 51) or contains an eccentric element (20, 25, 31, 51), said eccentric element (20, 25, 31, 51) being rotatably mounted such that the coupling region can be moved in the tensioning direction.

Description

Fuel cell assembly and method for its production

The invention relates to a fuel cell assembly having an upper end plate, a lower end plate, and a plurality of fuel cells stacked between the upper end plate and the lower end plate. Further comprising at least one tensioning means acting between the upper end plate and the lower end plate for applying a tensile force between the upper end plate and the lower end plate along a tensioning direction, a fastener for mechanically coupling between tensioning means and at least one of the end plates and / or between two tensioning means and a Coupling region in which the tensioning means and the fastener are connected together. Furthermore, the present invention relates to a method for producing a fuel cell assembly according to claim 9.

Devices for compressing fuel cell stacks are known and used in various types of fuel cells. Because of a

Fuel cell delivered voltage is determined by the electrochemical processes in the fuel cell are connected in series

Fuel cells used to provide a multiple of this voltage. The stacking of the individual fuel cells has proven to be a fuel cell stack. Especially in the area of the active area, in the middle of the stack, different operating conditions such as operating temperature and humidity cause a change in the absolute height of the plant

Fuel cell stack (the stack is breathing). Nevertheless, in order to ensure sufficient gas and cooling water tightness at all times, a certain stability of the stack must always be ensured, ie it must be ensured that a sufficiently great compression always acts on the seals in the cell stack. The provision of sufficient stability is of fundamental importance and especially in mobile applications, for example in the automotive sector, particularly important.

To increase the stability of fuel cell stacks, various solutions are known in the art. These solutions include applying an external force to the stack ends, as well as bonding the individual fuel cells. Furthermore, concepts are known in which tie rods are guided laterally on the outside of the stack through through holes in a compression end plate. The necessary force is generated in each case by means of springs, which are placed on the tie rod. As a rule, the end of the tie rod is threaded, so that the springs can be biased by a nut.

In the prior art devices are known which the

Clamp the fuel cell stack with tension bands. For example, DE 102006028498 A1 discloses such a fuel cell stack with tension bands. The tension straps each have a Einhängöffnung, with which they in a stretched state in corresponding hooks which laterally on an end plate of the

Fuel cell stack are, can be hung.

However, the known solutions have various disadvantages. bonded

Fuel cell stacks can be damaged by vibrations, for example, the use of tie rods requires comparatively much space and also has the disadvantage that the force is introduced into the end plates only selectively. To compensate for this, the plates used must be thick-walled in the region of the tensile layer. The known concepts, which use tensioning straps, are comparatively complex and expensive in assembly, since the straps are under tension

must be attached and often a large height is required to secure the pre-bent straps on the fuel cell stack.

The object of the invention is to provide a fuel cell assembly available, which has a space-saving, compact design and comparatively easy to assemble and thus is inexpensive.

This object is achieved by an arrangement according to claim 1 and a method for producing such an arrangement according to the independent claim 9. Advantageous embodiments of the invention are the subject of the dependent claims. The essential idea of the invention is to provide an arrangement in which the fastening element is either designed as an eccentric element or contains an eccentric element, wherein the eccentric element is designed such that its rotation allows the coupling region to be moved in the clamping direction and thus the bracing element stressed.

It is advantageous to arrange the straps laterally on the end plate. For this purpose, the plates are to be provided with appropriate fasteners. The

Tension bands can be attached to both the long sides and the narrow sides of the plates. The formation of at least one fastening element as an eccentric element or the fact that at least one fastening element comprises an eccentric element makes it possible to fasten the tensioning means without tension or under a comparatively low tension, since the eccentric element makes it possible to tighten the tensioning means after its assembly tighten. Advantageously, the fastening element is designed as an eccentric element, whereby the assembly is simplified. Further advantageously, the fastening element includes a

Eccentric element. This allows the use of prefabricated components and the better adaptation of the fastener to the given

Framework conditions, such as the height of the fuel cell stack or the material used for the tensioning agent. It is also possible to place the eccentric element between two tensioning means.

Advantageously, the fastening element is designed as an eccentric screw. For this purpose, a screw with an eccentric head is used. The eccentric screw is inserted into a corresponding hole located on the plate.

In a further preferred embodiment, the fastening element is as

Excenter rod formed. The tensioning means is fastened to the eccentric rod and tensioned by its rotation.

Advantageously, the upper end plate and / or the lower end plate includes at least one through hole through which the fastener is guided. Further advantageously, the length of the fastener is designed so that the

Fastener on both sides protrudes beyond the end plate. This first makes it possible for the tensioning means to be fastened on both sides of the fuel cell stack. In addition, the rotation of the eccentric causes the simultaneous Tension on both sides of the fuel cell stack. For clamping it is sufficient to have access to one side of the stack, which simplifies installation.

In a further preferred embodiment, the eccentric element includes a

Device which can receive a clamping tool. Such devices may be, for example, two holes for receiving a 2-pin key or a hexagon recess for receiving a hex wrench.

Preferably, the tensioning means includes a securing means, wherein the securing means is adapted to cause unwanted movement of the

Blocked eccentric element. This backup can be achieved with very simple means. For example, the eccentric can be locked by a locking screw or a locking pin so that it can not turn. It may be particularly advantageous for the eccentric element to be turned by no more than 180 degrees by turning to the left (counterclockwise). In this way, a locking screw with right-hand thread can not solve.

In a further preferred embodiment, the tensioning means is formed band or cord-shaped, wherein the tensioning means of different materials such. Cotton, metal, plastics or composite materials.

It is particularly advantageous if the tensioning means consists of an electrically insulating material or is coated with an electrically insulating material. As a result, short circuits in the fuel cell stack can be avoided.

Appropriately, the material used should have the lowest possible plastic deformability, especially over a longer period. Even a low material fatigue is advantageous. Depending on the type of fuel cell stack, a material having a suitable elongation and a suitable tensile strength is preferable.

Moreover, the invention relates to a method for producing a

Fuel cell assembly. Advantageously, it is possible to first compress the fuel cell stack to facilitate the bracing. The used

Eccentric elements are then brought into their "loading position", so they are arranged so that they tension the tensioning means as little as possible After the tensioning means have been fixed to the fastening element, the bracing of the Tensioning means by rotation of the eccentric element. The tightening is advantageously carried out with the aid of a clamping tool, which has a corresponding lever. The clamping force can be adjusted via the torque or the angle of rotation. Further advantageous, it is possible before attaching the

Verspannmittels to measure the height of the fuel cell stack and depending on the measured height to punch out or cut out the hole spacing of the two holes required in the tensioning means individually from the clamping band.

In a further preferred embodiment of the method, the eccentric element is removed from the fuel cell stack after the tensioning means has been braced. This is e.g. then possible if the fastening element is not formed as an eccentric element, but contains an eccentric element.

In the following the invention will be explained in more detail with reference to the drawing.

Showing:

1 is a schematic sectional view of a fuel cell stack 10.

2 shows a detailed view of two eccentric elements 20, 25.

Fig. 3 is a view of an end plate 12, 13 and an eccentric with

Locking screw 32.

4 shows a detailed view of FIG. 3.

Fig. 5 is an end plate 12, 13 with inserted eccentric rod 51st

6 shows a detailed view of FIG. 5 with a recognizable anti-rotation lock 62.

1 shows a schematic sectional view of a fuel cell stack 10. A plurality of fuel cells 11 together form a fuel cell stack which is bounded at its stack ends by a lower end plate 13 and an upper compression plate 14 and an upper end plate 12. Between the upper end plate 12 and the upper compression plate 14 spring elements 15 are arranged. These

Spring elements 15, which are supported on the upper end plate 12, bring the external force on the stack end, which generates the necessary compression on the seals in the cell stack 1 1. In addition, tensioning means 16 in the form of tension bands 16 and their fastening elements 17 are shown. Fig. 2 shows a schematic detail view of two eccentric elements 20, 25, which are eccentric discs. These each have a through hole 22, in the center of which the axis of rotation of the eccentric discs is arranged. Also recognizable are two receiving bores 21 for a clamping tool, in this case a two-pin wrench, and the support surface for a fastening screw 32. The two adjacent eccentric discs allow comparison between the loading position 20 and the achievable by a rotation of 180 ° position the maximum tension 25. The maximum between these positions

Adjustment path 26 thus represents the maximum possible tension along the

Clamping direction of the clamping band 16 is and is between the two

Positions representations shown. The tensioning means 16 is above a

Coupling region with the eccentric element in operative connection. This coupling region is also rotated by the amount of the

Adjustment path moves in the clamping direction.

Fig. 3 shows a view of an end plate 12 and an eccentric element with

Securing screw 32. This eccentric element is attached laterally to the end plate 12. The locking screw 32 is shown with a hexagonal recess and shown enlarged in the detail view of FIG. 4.

5 shows an end plate 12 with inserted eccentric rod 51. It can be seen that the eccentric rod 51 is guided through a bore in the end plate 12 and projects beyond the end plate 12 on both sides. As a result, the tension band 16 can be fastened.

FIG. 6 shows a detail view of FIG. 5, wherein a variant of an anti-rotation lock 62 can be seen. Perpendicular to the eccentric rod 51, a grub screw 62 or a locking pin 62 is placed, which the eccentric rod 51 in the desired

End position blocked. LIST OF REFERENCE NUMBERS

10 fuel cell stacks

11 fuel cells

12 upper end plate

13 lower end plate

14 compression plate

15 spring elements

16 tensioning agent

17 fasteners

20 eccentric disc in loading position

21 Mounting hole for clamping tool

22 through hole

23 bearing surface for fastening screw

25 eccentric disc with maximum tension

26 Maximum adjustment path

31 fastener

32 safety screw

51 eccentric rod

62 anti-rotation lock

Claims

claims

1. Fuel cell assembly with

an upper end plate (12),

a lower end plate (13),

a plurality of fuel cells (11) stacked between the upper end plate (12) and the lower end plate (13),

at least one between the upper end plate (12) and the lower one

End plate (13) acting tensioning means (16) for applying a tensile force between the upper end plate (12) and the lower end plate (13) along a clamping direction,

a fastening element (31) for mechanical coupling between

Tensioning means (16) and at least one of the end plates (12, 13) and / or between two tensioning means (16),

a coupling region in which the tensioning means (16) and the fastening element (17) are connected to one another, characterized in that the fastening element (17) is designed as an eccentric element (20, 25, 31, 51) or contains an eccentric element (20, 25 , 31, 51), wherein the eccentric element (20, 25, 31, 51) is rotatably mounted such that the coupling region in

Can move clamping direction.

2. Fuel cell assembly according to claim 1,

characterized in that

the fastening element (17) is designed as an eccentric screw.

3. Fuel cell assembly according to claim 1,

characterized in that

the fastening element (17) is designed as an eccentric rod (51).

4. Fuel cell assembly according to claim 3,

characterized in that

the upper end plate (12) and / or the lower end plate (13) includes at least one through bore through which the fastener (17) is guided.

5. Fuel cell arrangement according to one of claims 3 to 4,

characterized in that

the length of the fastener (17) is designed so that the

Fixing element (17) on both sides beyond the end plate (12, 13) protrudes.

6. Fuel cell arrangement according to one of claims 1 to 5,

characterized in that

the eccentric element (20, 25, 31, 51) contains a device which comprises

Can accommodate clamping tool.

7. Fuel cell arrangement according to one of claims 1 to 6,

characterized in that

the biasing means (16) includes securing means (62), the securing means (62) being adapted to block unwanted movement of the eccentric member (20, 25, 31, 51).

8. Fuel cell assembly according to one of claims 1 to 7, characterized

characterized in that the tensioning means (16) is formed band or cord-shaped.

9. A method for producing a fuel cell assembly according to any one of claims 1 to 8, comprising the steps:

Stacking a plurality of fuel cells (1) to a fuel cell stack (10),

Inserting the fastening elements (17) into the end plates and / or into the tensioning means (16), the eccentric elements (20, 25, 31, 51) being adjusted to their lowest position relative to the tensioning direction fixing the tensioning means (16) to the fastening element (17) clamping the tensioning means (16) by rotation of the eccentric element (20, 25, 31, 51)

10. The method according to claim 9,

characterized in that

the eccentric element (20, 25, 31, 51) after the bracing of the

Tensioning means (16) is removed.