1. Field of the Invention
The present invention relates to a fuel cell system.
2. Description of Related Art
In recent years, fuel cells, which generate electricity by using hydrogen (fuel gas) supplied to anodes and air containing oxygen (oxidizer gas) supplied to cathodes, has been developed and are expected as electric power sources for vehicles (e.g., fuel cell electric vehicles), etc.
As the electricity generation by such the fuel cell progresses, water vapor (water) is generated at the cathode of each MEA (Membrane Electrode Assembly) of the fuel cell, and part of the generated water permeates the MEA and then cross-leaks to the anode channel (fuel gas channel). Also, part of the cross-leaked water remains in the anode channel and adheres to the surface of the MEA, etc. The water adhering to the surface of the MEA obstructs the supply of hydrogen (fuel gas) to the anode (catalysts forming the anode). Consequently, the voltage (output) of the fuel cell can fall below a target voltage and electricity generation status of the fuel cell can degenerate to a poor condition.
In a technique proposed to solve the above problem, when the electricity generation status of a fuel cell has degenerated to a poor condition as above, gas and moisture remaining in the anode channel are purged (discharged) to the outside by temporarily raising the gas pressure in the anode channel and then briefly opening a purge valve (discharge valve) placed downstream of the anode channel (see JP 2008-112585 A).