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Method of forming a gasket assembly for a pem fuel cell assemblyRelated Patent Categories: Metal Working, Method Of Mechanical Manufacture, I.c. (internal Combustion) Engine Making, Seal Or Packing MakingMethod of forming a gasket assembly for a pem fuel cell assembly description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060236535, Method of forming a gasket assembly for a pem fuel cell assembly. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to proton-exchange membrane (PEM) fuel cells; more particularly, to gasketing for a PEM fuel cell; and most particularly, to an improved process for forming and using an elastomeric gasket to seal the edges of bipolar plates in a PEM fuel cell assembly. BACKGROUND OF THE INVENTION [0002] Proton-exchange membrane fuel cells are well known. In a PEM fuel cell, hydrogen atoms are ionized in an anode, migrate through a specialized membrane as hydrogen cations (protons), and combine with oxygen anions at a cathode to form water. Electrons from the hydrogen flow from the anode through an external circuit to the cathode, performing work in between. The membrane, typically with a catalyst coating sandwiched between layers of gas diffusion media (GDL), is know in the art as a membrane electrode assembly (MEA). A bipolar plate assembly is constructed by joining an individual anode and cathode plate. [0003] Fuel cell assemblies comprise a plurality of individual bipolar plate assemblies stacked together and connected in electrical series. When the MEA is captured between the anode and cathode they form an individual cell whereby the electrochemical reaction can take place. Such bipolar plates, when stacked together with the MEAs in between, form a fuel cell assembly. Openings through the bipolar plates near the edges form headers for inlet and exhaust of fuel and combustion gases as well as coolant. Other openings may be provided for alignment during assembly or for other specialized purposes. [0004] Bipolar plates typically are formed of a metals (such as titanium or stainless steel) or composites (such as a thermoset graphite-loaded vinyl ester polymer) and are easily damaged by twisting or other application of uneven stresses. The plates require a non-conductive seal or gasket along all outer edges and around all openings to prevent leaking of reactant gases and coolant and to electrically insulate the bipolar plates from each other. It is known to use separate die-cut or molded elastomeric gaskets, installed between the plates during assembly of a fuel cell stack. [0005] A problem exists in locating the gaskets properly with respect to the openings to be sealed. Further, individual gaskets are thin, very pliable, and thus are easily twisted and deformed. A misaligned or twisted gasket can cause leaks, broken bipolar plates, and stack failure. [0006] What is needed is a reliable method of forming and installing resilient gaskets in assembly of a fuel cell stack. [0007] It is a principal object of the present invention to improve the reliability of assembly of a fuel cell stack. [0008] It is a further object of the invention to reduce waste and cost in fuel cell manufacture. [0009] It is a still further object of the invention to improve ease of assembly of a fuel cell stack. SUMMARY OF THE INVENTION [0010] Briefly described, in a method of forming a gasket assembly for a fuel cell assembly, a thermoplastic carrier sheet is die-cut to have a size and shape matching that of a bipolar plate, including various cutouts known in the art for passage of reactant gases, spent gases, coolant, and placement of a membrane electrode assembly. A plurality of holes are also punched in the carrier sheet in the pattern of gasket beading to be formed subsequently. In a gasket mold, liquid gasket material fills the mold on both sides of the carrier sheet to form gasket elements on both sides, flowing through the holes in the sheet and thereby causing the gasket elements to become mechanically attached to the sheet and to each other. Different liquid gasket materials can be used to suit the performance demands of the local environment. Preferably, a pre-molded plastic carrier element having a flange portion substantially identical with the outer profile of the bipolar plate is then overmolded onto the sheet. Alternately, locator features are provided in the outer regions of the sheet to aid in accurately locating the gasket elements. [0011] During assembly of a fuel cell assembly, the plastic carrier element fits over a bipolar plate, automatically positioning the gasket correctly on the plate. The carrier sheet prevents the gasket from twisting or shifting. In a currently preferred embodiment, a membrane electrode assembly is attached as by ultrasonic welding within an appropriate opening in the carrier sheet. [0012] A gasket assembly in accordance with the invention provides the following benefits over prior art gasketing schemes: [0013] Eliminates need for bonding a gasket to a bipolar plate. [0014] Prevents twisting, stretching, and rolling of a gasket. [0015] Aligns the gasket to a bipolar plate so that the gasket is placed correctly in a gasket groove therein. [0016] Aligns adjacent bipolar plates, greatly simplifying stack assembly. [0017] Provides a positive stop, limiting compression of the gasket during assembly. [0018] Provides electrical isolation of the bipolar plates. [0019] Simplifies installation of membrane electrode assemblies during stack assembly. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Continue reading about Method of forming a gasket assembly for a pem fuel cell assembly... Full patent description for Method of forming a gasket assembly for a pem fuel cell assembly Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of forming a gasket assembly for a pem fuel cell assembly patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method of forming a gasket assembly for a pem fuel cell assembly or other areas of interest. ### Previous Patent Application: Method for manufacturing printed wiring board Next Patent Application: Method for fabricating a monolithic fluid injection device Industry Class: Metal working ### FreshPatents.com Support Thank you for viewing the Method of forming a gasket assembly for a pem fuel cell assembly patent info. 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