(12) United States Patent ao) Patent No.: Us 7,829,233 B2
Kizaki (45) Date of Patent: Nov. 9,2010
§ 371 (c)(1),
(2), (4) Date: Nov. 19, 2007 (87) PCT Pub. No.: WO2007/018132 PCT Pub. Date: Feb. 15, 2007
(65) Prior Publication Data
US 2009/0047553 Al Feb. 19, 2009
(30) Foreign Application Priority Data
Aug. 9,2005 (JP) 2005-231368
(51) Int. CI.
(52) U.S. CI 429/443; 429/444; 429/448
(58) Field of Classification Search 429/22,
429/25, 24, 34, 13, 17, 12; 702/58; 340/635 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
5,763,765 A * 6/1998 Lamontetal 73/40.7
A high-precision gas leak judgment comparable to that when the fuel cell is operating normally is achieved even when a fuel cell is restarted. A gas leak judgment unit (for example ECU 13) forjudging gas leak in a closed space formed in a fuel gas system refers to a gas leak judgment value based on pressure change in the closed space detected by a pressure sensor to judge gas leak and, in addition, varies the fuel gas leak judgment level in response to nitrogen concentration in a fuel electrode. The varying of gas leak judgment level in response to the nitrogen concentration takes into account a temporary rise in the nitrogen concentration in the fuel electrode that occurs when a fuel cell stack is restarted and, in this case, it is preferable that the gas judgment value be altered in response to the nitrogen concentration.
5 Claims, 5 Drawing Sheets