Method for producing a bipolar plate

Abstract

A method for producing a bipolar plate for a fuel cell stack includes the following steps: providing two half-plates made of sheet metal, which form the bipolar plate when arranged on top of one another, wherein the half-plates are profiled via deformation of the sheet metal, and wherein, as a result of the profiling, the two half-plates arranged on top of one another contact at at least one contact region and do not contact at at least one non-contact region; carrying out at least one first cut in the non-contact region of at least one half-plate, before the half-plates are arranged on top of one another; Arranging the two half-plates on top of one another and connecting same; and carrying out at least a second cut in the contact region through both half-plates after they have been arranged on top of one another and connected.

Claims

1. A method for producing a bipolar plate for a fuel cell stack, the method comprising the steps of: (i) providing two half-plates made of sheet metal which result in the bipolar plate when placed over one another, wherein the two half-plates are profiled by forming the sheet metal, and wherein, by virtue of the profiling, the two half-plates placed over one another come into contact at at least one contact region and do not come into contact at at least one noncontact region; (ii) carrying out at least one first cut in the noncontact region of at least one half-plate before the half-plates are placed onto one another and connected; (iii) placing the two half-plates onto one another and connecting them; and (iv) carrying out at least one second cut in the contact region through both half-plates after they have been placed onto one another, wherein the at least one second cut in the contact region cuts out a port disposed through both half-plates; wherein step (iv) is carried out after the two half-plates have been connected to each other by welding and/or by adhesive bonding and/or by brazing; wherein the two half-plates are pressed onto one another during connection, wherein pressure is applied at at least one pressing region which is at least partially severed by the second cut to form the port.

2. The method as claimed in claim 1, wherein at least one first cut is carried out by mechanical cutting, wherein, during the mechanical cutting, the half-plate lies on a shaped supporting tool which corresponds to the profile of the half-plate, with the result that the half-plate is supported with full-surface contact on the supporting tool.

3. The method as claimed in claim 1, wherein the forming of the sheet metal for the profiling and a mechanical cutting for the at least one first cut are carried out in a common tool.

4. The method as claimed in claim 3, wherein the forming of the sheet metal for the profiling and the mechanical cutting for the at least one first cut are carried out in the common tool simultaneously.

5. The method as claimed in claim 1, wherein at least one first cut is carried out by thermal cutting.

6. The method as claimed in claim 5, wherein the thermal cutting is laser cutting.

7. The method as claimed in claim 6, wherein at least one second cut is carried out by mechanical cutting and/or at least one second cut is carried out by thermal cutting.

8. The method as claimed in claim 1, wherein at least one second cut is carried out by mechanical cutting and/or at least one second cut is carried out by thermal cutting.

9. A fuel cell stack, comprising a plurality of stacked bipolar plates, produced by the method as claimed in claim 1.

10. A vehicle, comprising a fuel cell stack as claimed in claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a bipolar plate according to an exemplary embodiment produced by the method according to the invention.

(2) FIG. 2 shows a sectional view of FIG. 1.

(3) FIGS. 3 and 4 show schematic illustrations for mechanical cutting by the method according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) A method according to the invention for producing a bipolar plate 1 is described with reference to FIGS. 1 to 4. The figures show the bipolar plate 1 and the method steps in schematically simplified form.

(5) FIG. 1 shows the bipolar plate 1. The bipolar plate 1 has a plurality of ports 2 in the form of cutouts in the upper and lower region. A plurality of the bipolar plates 1 are stacked to produce a fuel cell stack. Here, the individual ports 2 are aligned and thereby form ducts, six of them in the example shown. The ducts in the fuel cell stack are used for distributing the reactants and, where appropriate, cooling media to the individual bipolar plates 1.

(6) FIG. 2 shows a detail section through the bipolar plate 1. The bipolar plate 1 is composed of two half-plates 3. To produce the bipolar plate 1, the two half-plates 3 are, where appropriate, connected to one another, in particular welded.

(7) The individual half-plates 3 are made of sheet metal and profiled. This profiling of the half-plates 3 is produced by forming the sheet metal. The two outer sides of the bipolar plate 1 form the anode side 6 and cathode side 7. Here, the profiling is used to channel and distribute the reactants.

(8) The two half-plates 3 are profiled and placed over one another in such a way that contact regions 4 and noncontact regions 5 result. In the noncontact region 5, a cavity 8 remains between the two half-plates 3. Such a cavity 8 can remain unused or can be used for channeling media in the bipolar plate.

(9) FIG. 2 in particular shows the profile of the bipolar plate 1 in greatly enlarged and simplified form. In fact, the profiling of the half-plates 3 can be designed to be very fine and complex. The individual port 2 for example can extend over a plurality of the contact regions 4 and noncontact regions 5.

(10) As has already been described, the individual half-plates 3 are cut in the noncontact region 5 even before they have been placed onto one another and/or connected. These cuts are referred to as first cuts 11. After the two half-plates 3 have been connected, the half-plates 3 or the bipolar plate 1 are or is cut in the contact region 4. These cuts are referred to as second cuts 12.

(11) It is preferably provided that, after the two half-plates 3 have been connected, exclusively second cuts 12, that is to say cuts in the contact region 4, are carried out at least to cut out the ports 2. This makes it possible to avoid deformation of the bipolar plate 1 and/or an extreme burr formation.

(12) FIGS. 3 and 4 show how a mechanical cutting of the first cuts 11 can be carried out on a profiled half-plate 3. For this purpose, a profiled supporting tool 9 is used. The supporting tool 9 corresponds in its shape to the profiling of the half-plate 3. As a result, the half-plate 3 can bear with full-surface contact on the supporting tool 9.

(13) FIG. 3 shows a schematic plan view. Dashed lines are used to represent the full-surface bearing of the half-plate 3 on the supporting tool 9. It is only directly around the first cut 11 that there is situated a cutting region 10 in which the half-plate 3 does not bear with full-surface contact. Here, there is preferably provision that the half-plate 3 bears fully peripherally around the cutting region 10 with full-surface contact on the supporting tool 9. This makes it possible to substantially avoid unwanted deformations when carrying out the first cut 11.

(14) The second cut 12 illustrated in FIG. 3, for example by means of mechanical cutting or thermal cutting, is carried out only after the two half-plates 3 have been placed onto one another and connected.

(15) As the schematic sectional illustration in FIG. 4 shows, the cutting region 10 and the first cut 11 are situated in a noncontact region 5 of the half-plate 3. After the two half-plates 3 have been assembled, such a supporting tool 9 can no longer be used for making the first cut 11 since the cavity 8 is no longer accessible in this state.

(16) It is also possible to carry out the first cut 11 or the first cuts 11 only on one of the two half-plates 3.

(17) A profiled supporting tool 9 can also be used for the second cut 12, for example if the first cut 11 is carried out only on one of the two half-plates 3.

(18) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF REFERENCE SIGNS

(19) 1 Bipolar plate 2 Ports 3 Half-plates 4 Contact region 5 Noncontact region 6 Anode side 7 Cathode side 8 Cavities 9 Supporting tool 10 Cutting region 11 First cut 12 Second cut