Patent ID: 8722269

Claim:
A scavenging method of a fuel cell system, wherein: the fuel cell system includes: a fuel cell stack in which a cathode gas and an anode gas are respectively supplied to a cathode gas passage and an anode gas passage so as to generate electric power; a scavenging gas supply device for supplying a scavenging gas to the fuel cell stack; and a scavenging switching valve for performing switching between first scavenging for performing scavenging by supplying the scavenging gas to the cathode gas passage, and second scavenging for performing scavenging by supplying the scavenging gas to the anode gas passage; and the method comprises the steps of: performing the first scavenging; controlling the pressure of the scavenging gas by making the pressure of the scavenging gas at the upstream side with respect to the scavenging switching valve be lower than the pressure of the scavenging gas during the first scavenging; and switching the scavenging switching valve after the pressure of the scavenging gas at the upstream side with respect to the scavenging switching valve is lower than the pressure of the scavenging gas during the first scavenging.