The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 2004
Filed:
Feb. 13, 2002
Stephen Raiser, Egelsbach, DE;
Hartmut Hinz, Kronberg, DE;
General Motors Corporation, Detroit, MI (US);
Abstract
An electrical isolation system is provided for a fuel cell stack as well as a method of operating the fuel cell stack. The stack comprises a plurality of fuel cells connected in series and a coolant circuit for cooling said fuel cells in operation using a liquid coolant having a restricted electrical conductivity. The stack is associated with a chassis having a chassis ground and comprising a plurality of coolant passages for said fuel cells. The coolant circuit comprises a plurality of conductive components such as an outer boundary wall of the fuel cell stack, a radiator and/or a pump at least one of which is connected to said chassis ground. A measuring circuit is provided for measuring the resistance between a selected one of the fuel cells and the chassis ground and a monitoring circuit provides a warning signal, or disengages the connection to the output terminals of the stack or shuts down the stack if the resistance reaches a critical value.