Patent ID: 6709779
Filing Date: 2004-03-23
Classification: H01M,Y02E

Abstract:
A cooling device using a cooling medium for a fuel cell stack, comprising:a heat exchanger which cools the cooling medium; a cooling passage through which the cooling medium is circulated between the fuel cell stack and the heat exchanger; a pump which pressurize the cooling medium in the cooling passage for circulation; a bypass passage which bypasses the fuel cell stack to directly circulate a part of the cooling medium discharged from the pump to the heat exchanger; an electrical conductivity reducing mechanism which reduces an electrical conductivity of the cooling medium passing through the bypass passage; a valve which regulates a bypass amount of the cooling medium passing through the bypass passage; a sensor which detects an electrical conductivity of the cooling medium; and a programmable controller programmed to: determine if the electrical conductivity is larger than a predetermined conductivity; control the valve to increase the bypass amount when the electrical conductivity is larger than the predetermined conductivity; determine if a predetermined condition related to an operation of the fuel cell stack holds; and control the valve to prevent the bypass amount from becoming zero when the electrical conductivity is not larger than the predetermined conductivity and the predetermined operation condition holds.