Injected metal bead channel seal achieved through stamped plate features on fuel cell bipolar plates

Patent metadata

Field	Value
Publication number	US-9847536-B2
Application number	US-201514681504-A
Country	US
Kind code	B2
Filing date	Apr 8, 2015
Priority date	Apr 8, 2015
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A fuel cell system with reduced leakage and a method of assembling a fuel cell system. Bipolar plates within the system include reactant channels and coolant channels that are fluidly coupled to inlet and outlet flowpaths, all of which are formed within a coolant-engaging or reactant-engaging surface of the plate. One or more seals are also formed on the fluid-engaging surface to help reduce leakage by maintaining fluid isolation of the reactants and coolant as they flow through their respective channels and flowpaths that are defined between adjacently-placed plates. The seal—with its combination of in-plane and out-of-plane dimensions—forms a substantially hollow volume, into which a plug is placed to reduce the tendency of the seal to form a shunted flow of the coolant or reactant around the intended active area of the plate. A fluid port intersection is integrally formed with the seal and is formed to be fluidly cooperative with the volume, and is capable of accepting the introduction of a fluent precursor of the plug material such that upon curing, the precursor material forms a substantially rigid insert that continuously fills both the volume and intersection, thereby increasing the resistance of the plug to movement and the seal to shunted flow. In one form, the geometry of the fluent material injection site is such that it promotes plug anchoring within its intended location, while also providing a manufacturing aid to visually inspect for plug installation, as well as to serve as a bipolar plate stacking alignment locator and verification.

First claim

I claim:

1. A fuel cell system defining a plurality of fuel cells arranged in a stacked configuration, each of the cells within the system comprising:
a membrane electrode assembly; and
a bipolar plate placed in fluid cooperation with the membrane electrode assembly, the plate defining a fluid-engaging surface and comprising:
at least one of reactant channels and coolant channels defined in the fluid-engaging surface;
inlet and outlet flowpaths defined in the fluid-engaging surface such that both are in fluid communication with a respective one of the reactant and coolant channels;
at least one seal disposed on the fluid-engaging surface such that upon cooperative engagement with an adjacently-placed one of the plates, the seal provides substantial fluid isolation of a fluid that is being conveyed through a respective one of the reactant and coolant channels, the seal defining a substantially hollow volume and a fluent material introduction aperture formed therein; and
a plug disposed within at least a portion of the volume that is adjacent the aperture, the plug defined by at least a portion of fluent material being introduced through the aperture such that upon curing the plug forms a substantially rigid insert that substantially blocks leakage flow through the volume,

wherein the plug is defined by differing material hardness values at various locations within the at least one seal.

2. The fuel cell system of claim 1 , wherein the cooperative engagement between the seal on a first of the stacked plates and an adjacently-placed second of the stacked plates comprises contact between the seal disposed on the first plate and a substantially planar surface of the second plate.

3. A vehicle comprising the fuel cell system of claim 1 .

4. A fuel cell bipolar plate defining a substantially planar fluid-engaging surface, the plate comprising:
at least one of reactant channels and coolant channels defined in the fluid-engaging surface;
inlet and outlet flowpaths defined in the fluid-engaging surface such that both are in fluid communication with a respective one of the reactant and coolant channels;
at least one seal disposed on the fluid-engaging surface such that upon cooperative engagement with an adjacently-placed one of the plates, the seal provides substantial fluid isolation of a fluid that is being conveyed through a respective one of the reactant and coolant channels, the seal defining a substantially hollow volume and a fluent material introduction aperture formed therein; and
a plug disposed within at least a portion of the volume that is adjacent the aperture, the plug defined by at least a portion of fluent material being introduced through the aperture such that upon curing the plug forms a substantially rigid insert that substantially blocks leakage flow through the volume,
wherein the plug is defined by differing material hardness values at various locations within the seal.

5. The plate of claim 4 , wherein the fluid-engaging surface defines (a) an active region corresponding to the reactant and flowpath channels, and (b) a manifold region corresponding to the inlet and outlet flowpaths.

6. The plate of claim 5 , wherein the seal comprises a plurality of seals, each forming a substantially peripheral path around one of the reactant and flowpath channels and the inlet and outlet flowpaths within respective active and manifold regions.

7. The plate of claim 4 , wherein the seal is integrally formed as a part of the fluid-engaging surface.

8. The plate of claim 7 , wherein the seal defines a substantially peripheral path around at least one of an active region and a manifold region that are defined within the fluid-engaging surface.

9. The plate of claim 8 , wherein the aperture is defined in an intersection that is formed in the seal such that the intersection defines a laterally projecting additional volume in the seal.

10. The plate of claim 4 , wherein the plate is formed of a laminate of at least two sheets such that a lower sheet defines a substantially planar lower surface and an upper plate defines the fluid-engaging surface so that the volume is defined by cooperative engagement of the two sheets.

11. A method of sealing a bipolar plate within a fuel cell system, the method comprising:
placing at least a pair of plates on top of one another in a stacked configuration, at least one of the plates defining a fluid-engaging surface thereof and comprising:
at least one of reactant channels and coolant channels defined therein;
inlet and outlet flowpaths defined therein such that each are in fluid communication with a respective one of the reactant and coolant channels; and
at least one seal disposed on the fluid-engaging surface such that upon cooperative engagement between the pair of plates, the seal provides substantial fluid isolation of a reactant or coolant that is being conveyed through a respective one of the reactant and coolant channels, the seal defining a substantially hollow volume therein; and

introducing a fluent material into an aperture formed in the volume such that the volume occupies a substantial cross-sectional entirety defined by the volume at least in a region within the seal that is adjacent a location within the seal where the fluent material is introduced; and
curing the material such that it forms a substantially rigid plug in the seal region, the plug defining differing material hardness values at various locations within the seal region.

12. The method of claim 11 , wherein the fluid-engaging surface defines a coolant path.

13. The method of claim 11 , wherein the fluid-engaging surface defines (a) an active region corresponding to the reactant and flowpath channels, and (b) a manifold region corresponding to the inlet and outlet flowpaths.

14. The method of claim 13 , wherein the seal comprises a plurality of seals, each forming a substantially peripheral path around one of the reactant and flowpath channels and the inlet and outlet flowpaths within respective active and manifold regions.

15. The method of claim 14 , wherein the aperture is defined in an intersection that is fluidly cooperative with the volume.

16. The method of claim 11 , further comprising establishing visual indicia of a presence of the fluent material within the volume.

17. The method of claim 16 , wherein the visual indicia is defined by the fluent material being formed with a pigment that provides a color contrast relative to the seal.

18. The method of claim 16 , wherein establishing visual indicia comprises using a computer controlled vision system.

19. The method of claim 11 , further comprising establishing visual indicia with the aperture to indicate alignment of the at least a pair of the plates within the stacked configuration.

20. The method of claim 19 , wherein placing at least a pair of plates on top of one another in a stacked configuration comprises laser welding the plates together into a bipolar plate assembly prior to introducing the fluent material.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Freese V Charles E

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/028

  Sealing means characterised by their material · CPC title

• H01M8/0271

  Sealing or supporting means around electrodes, matrices or membranes · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M8/0286

  Processes for forming seals · CPC title