BIPOLAR PLATE, FUEL CELL SYSTEM, AND METHOD FOR MANUFACTURING A BIPOLAR PLATE

Abstract

The present invention relates to a bipolar plate (100, 200, 403, 405, 407, 409, 500) for a fuel cell, wherein the bipolar plate (100, 200, 403, 405, 407, 409, 500) comprises at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) for transporting operating fluids of the fuel cell, wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises an inlet opening for introducing fluid into the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) and an outlet opening for fluid exiting the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501), wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises a first region (107, 211, 503) and at least one second region (109, 213, 507), and wherein the at least one second region (109, 213, 503) has a cross-section which is reduced compared to the first region (107, 211, 507) in order to adjust a volumetric flow of fluid which exits the outlet opening.

Claims

1. A bipolar plate (100, 200, 403, 405, 407, 409, 500) for a fuel cell, wherein the bipolar plate (100, 200, 403, 405, 407, 409, 500) comprises at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) for transporting operating fluids for the fuel cell, wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises an inlet opening for introducing fluid into the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) and an outlet opening for fluid exiting the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501), wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises a first region (107, 211, 507) and at least one second region (109, 213, 503), and wherein the at least one second region (109, 213, 503) has a reduced cross-section compared to the first region (107, 211, 507) in order to adjust a volumetric flow of fluid exiting the outlet opening.

2. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) in the at least one second region (109, 213, 503) is narrowed by a depression and/or by a material accumulation toward a flow region of the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501).

3. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises a roof region, a bottom region, and two flanks connecting the roof region and the bottom region on respective sides of the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501), and wherein at least one flank and/or the roof region and/or the bottom region in the at least one second region (109, 213, 503) is narrowed relative to the first region (107, 211, 507) toward a flow region of the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501).

4. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) comprises a coolant channel for directing coolant, a hydrogen channel for directing hydrogen, and/or an air channel for directing air.

5. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the bipolar plate (100, 200, 403, 405, 407, 409, 500) comprises a plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) and respective fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) of at least a portion of the plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) have a different cross-section relative to one another in the at least one second region (109, 213, 503).

6. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the bipolar plate (100, 200, 403, 405, 407, 409, 500) comprises a plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) and respective second regions of at least a portion of the plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) differ from one another in their position along the bipolar plate (100, 200, 403, 405, 407, 409, 500).

7. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein the bipolar plate (100, 200, 403, 405, 407, 409, 500) comprises a plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) and respective second regions of the plurality of fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) are shaped in such a way that volumetric flows of fluid flowing out of the respective fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) differ from one another at most by a predetermined variance.

8. The bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1, wherein respective fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) arranged at an edge of the bipolar plate (100, 200, 403, 405, 407, 409, 500) have a narrower cross-section than fluid channels in a center of the bipolar plate (100, 200, 403, 405, 407, 409, 500).

9. A method (300) of manufacturing a bipolar plate (100, 200, 403, 405, 407, 409, 500), wherein the method comprises: a provisioning step (301) in which a bipolar plate (100, 200, 403, 405, 407, 409, 500) with at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) extending between an inlet opening and an outlet opening is provided, a processing step (303) in which a cross-section of the at least one fluid channel (101, 103, 105, 201, 203, 205, 207, 209, 501) in a second region (109, 213, 503) is narrowed compared to a cross-section of a first region (107, 211, 507) in order to adjust a volumetric flow of fluid exiting the outlet opening.

10. The method (300) according to claim 9, wherein in the processing step (303), various fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) for directing various fluids are processed in a concerted manner in order to adjust a predetermined distribution pattern.

11. The method (300) according to claim 9, wherein in the processing step (303), various fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) for directing various fluids are narrowed by material accumulations in order to adjust fluid flows through respective fluid channels (101, 103, 105, 201, 203, 205, 207, 209, 501) independently of one another.

12. A fuel cell system (400) comprising at least one bipolar plate (100, 200, 403, 405, 407, 409, 500) according to claim 1.

13. The fuel cell system (400) according to claim 12, wherein the fuel cell system comprises a plurality of bipolar plates (100, 200, 403, 405, 407, 409, 500), wherein respective bipolar plates (100, 200, 403, 405, 407, 409, 500) differ in their fluid channel geometries in order to adjust a volumetric flow through the entire fuel cell system (400).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Shown are:

[0053] FIG. 1 a possible embodiment of the bipolar plate according to the invention,

[0054] FIG. 2 a further possible embodiment of the bipolar plate according to the invention,

[0055] FIG. 3 a possible embodiment of the method according to the invention,

[0056] FIG. 4 a possible embodiment of the fuel cell system according to the invention,

[0057] FIG. 5 a further possible embodiment of the bipolar plate according to the invention.

DETAILED DESCRIPTION

[0058] FIG. 1 shows a bipolar plate 100. The bipolar plate 100 comprises a first fluid channel 101, a second fluid channel 103, and a third fluid channel 105 for directing a fluid, such as a coolant.

[0059] In order to achieve even supply of fluid to an active field of a fuel cell, the second fluid channel 103 comprises a first region 107 and a second region 109. The second region 109 is narrowed in its cross-section compared to the first region 107. To this end, a roof region of the fluid channel 103 was narrowed or compressed in the second region 109.

[0060] Due to the narrowing of the second fluid channel 103, a volumetric flow flowing through the second fluid channel 103 is reduced compared to a volumetric flow flowing through the first fluid channel 101 and the third fluid channel 105. Accordingly, for example, a compressor-related oversupply of fluid to the second fluid channel 103 can be compensated through the narrowing in the second region 109 so that the respective volumetric flows exiting the first fluid channel 101, the second fluid channel 103, and the third fluid channel 105 differ from one another by at most a predetermined variance.

[0061] Due to the matched volumetric flows exiting the first fluid channel 101, the second fluid channel 103, and the third fluid channel 105, the bipolar plate 100 supplies fluid particularly evenly to an active field of a fuel cell so that local temperature peaks and/or power peaks and corresponding fuel cell stresses are avoided.

[0062] Alternatively, the narrowing in the second region 109 of the second fluid channel 103 may be used to enhance differences in respective volumetric flows flowing through the first fluid channel 101, the second fluid channel 103, and the third fluid channel 105. For example, in the case that fluid flows particularly strongly through fluid channels located at respective edges, i.e., the first fluid channel 101 and the third fluid channel 105, the narrowing in the second region 109 can result in fluid flowing through the first fluid channel 101 and the third fluid channel 105 even more strongly, and respective regions supplied with fluid by the first fluid channel 101 and the third fluid channel 105 are supplied with fluid particularly strongly in order to, for example, compensate for particularly high thermal stress in these regions of the fuel cell.

[0063] FIG. 2 shows a bipolar plate 200. The bipolar plate 200 comprises a first fluid channel 201, a second fluid channel 203, a third fluid channel 205, a fourth fluid channel 207, and a fifth fluid channel 209.

[0064] While the first fluid channel 201, the second fluid channel 203, and the third fluid channel 205 are used to direct a first fluid, such as a coolant, the fourth fluid channel 207 and the fifth fluid channel 209 are configured for directing further fluids, such as hydrogen and air.

[0065] Here, the fourth fluid channel 207 comprises a first region 211 and a second region 213. The second region 213 is reduced by narrowings 215 in its cross-section compared to the cross-section of the first region 211.

[0066] The narrowings 215 may be produced by deformation of a flank of the first fluid channel 201, wherein the thereby produced enlargement in the volume of the first fluid channel 201 has an only little or not significant effect on a volumetric flow of fluid flowing through the first fluid channel 201.

[0067] In order to eliminate an effect of the narrowings 215 on the volumetric flow flowing through the first fluid channel 201, the narrowings may optionally be formed by material accumulations on the flank of the first fluid channel 201 or on the flank of the fourth fluid channel 207 so that a volume of the first fluid channel 201 is unchanged compared to a volume of the, for example, third fluid channel 205, on which no narrowings are arranged.

[0068] FIG. 3 shows a method 300 for manufacturing a bipolar plate. The method 300 comprises a provisioning step 301, in which a bipolar plate comprising at least one fluid channel extending between an inlet opening and an outlet opening is provided, and a processing step 303, in which a cross-section of the at least one fluid channel is narrowed in some regions in order to adjust a volumetric flow of fluid exiting the outlet opening.

[0069] FIG. 4 shows a fuel cell system 400. The fuel cell system 400 comprises a fuel cell stack 401 comprising a plurality of bipolar plates 403 to 409, each comprising a plurality of fluid channels having cross-sections narrowed at least partially in some regions. In this case, the narrowed cross-sections of the respective bipolar plates 403 to 409 are concerted in such a way that a predetermined distribution pattern of fluids flowing through the fuel cell system 400 is adjusted.

[0070] In particular, a first bipolar plate 403 may have a particularly large number of fluid channels with narrowings and a second bipolar plate 405 may have a particularly small number of fluid channels with narrowings so that a particularly small quantity of fluid is supplied to regions of the fuel cell system 400 supplied with fluid by the first bipolar plate 403 and a particularly large quantity of fluid is supplied to regions of the fuel cell system 400 supplied with fluid by the second bipolar plate 405. This can in particular alleviate or rectify the problem that an uneven media distribution arises in a fuel cell stack consisting of fuel cells having the same channel geometries.

[0071] FIG. 5 shows a bipolar plate 500 with a fluid channel 501. The fluid channel is compressed at its flanks 505 in a second region 503. Correspondingly, a volumetric flow flowing through a first region 507 into the second region 503 is throttled or reduced due to a cross-section that is reduced in the second region 503 compared to the first region 507.

[0072] Due to its reduced cross-section, the second region 503 causes an adaptation of a volumetric flow exiting the fluid channel 501 to further volumetric flows exiting the bipolar plate 500 so that a homogeneous distribution pattern of volumetric flows arises in an active field of a fuel cell system supplied with fluid by the bipolar plate 500, the throttling, i.e., the reduction of the cross-section of the fluid channel 501 in the second region 503, an adjustment of a volumetric rate flowing through the fluid channel 501 takes place independently of further volumetric flows flowing through further fluid channels of the bipolar plate 500. Accordingly, manufacturing tolerances of the fluid channel 501 can be compensated. Furthermore, a particularly homogeneous distribution pattern of volumetric flows flowing to the active field can be achieved.

[0073] The homogeneous distribution pattern of volumetric flows flowing to the active field is achieved by means of the bipolar plate 500, a particularly even stress on the active field and, as a result, a service life of the fuel cell system is maximized.