FUEL CELL SYSTEM

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of changing air flow channels even in the case a pressure loss is small at a bypass channel, in a system equipped with a bypass channel bypassing a cooling unit. SOLUTION: The fuel cell system 1 is provided with a bypass tube 31 communicating an upstream side and a downstream side of the cooling unit 22 out of an air supply tube 23, a bypass valve 32 fitted to the air supply tube 23 for adjusting an air volume flowing in the cooling unit 22, a check valve 33 fitted in free opening and closing to the bypass tube 31 and opening when a difference between an internal pressure and a back pressure of the bypass tube 31 exceeds a given value, a back pressure guide tube 34 guiding in the internal pressure at a downstream side of the cooling unit 22 of the air supply tube 23 as a back pressure of the check valve 33, an atmospheric air opening tube 35 communicating the back pressure guide tube 34 with the outside, and a relief valve 351 fitted to the atmospheric air opening tube 35 for opening and closing the atmospheric air opening tube 35. COPYRIGHT: (C)2009,JPO&INPIT