| CPC H01M 8/04761 (2013.01) [H01M 8/0438 (2013.01); H01M 8/04097 (2013.01); H01M 8/04156 (2013.01); H01M 8/04201 (2013.01); H01M 2250/20 (2013.01)] | 1 Claim |
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1. A fuel cell system comprising:
a fuel cell stack;
a fuel gas supply path through which a fuel gas is supplied to the fuel cell stack;
an injector provided in the fuel gas supply path;
an ejector provided in the fuel gas supply path and provided between the injector and the fuel cell stack;
a circulation path through which a fuel off gas discharged from the fuel cell stack is supplied to the ejector;
a pressure difference detection unit configured to detect a pressure difference between an ejector inlet port pressure that is a pressure in the circulation path between the fuel cell stack and the ejector, and an ejector outlet port pressure that is a pressure in the fuel gas supply path between the ejector and the fuel cell stack; and
a control device,
wherein the control device is configured to
calculate a required circulation flow rate that is a flow rate required for the fuel off gas to be supplied from the fuel cell stack to the ejector, based on a required load for the fuel cell stack,
calculate an estimated circulation flow rate that is an estimated value of a flow rate of the fuel off gas supplied from the fuel cell stack to the ejector, based on the required load and the pressure difference, and
increase a flow rate of the fuel gas to be supplied from the injector to the fuel cell stack when the estimated circulation flow rate is lower than the required circulation flow rate;
the fuel system further comprising:
a gas-liquid separator provided in the circulation path to separate liquid water contained in the fuel off gas and store the liquid water;
an exhaust-drainage path connected to the gas-liquid separator; and
an exhaust-drainage valve provided in the exhaust-drainage path,
wherein the control device is configured to:
specify a required upper limit value and a required lower limit value which correspond to the ejector outlet port pressure based on the required load,
stop driving the injector when the ejector outlet port pressure is equal to or more than the required upper limit value with the injector in a driven state, and
start driving the injector when the ejector outlet port pressure is equal to or less than the required lower limit value with the injector in a stopped state, and
wherein the control device switches the exhaust-drainage valve to an open state to exhaust a nitrogen gas contained in the fuel off gas in the gas-liquid separator to outside when the estimated circulation flow rate is lower than the required circulation flow rate and the required upper limit value specified based on the required load is equal to or more than a predetermined upper limit pressure value.
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