Fuel cell system
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsShinji Aso, Shigeto Kajiwara, Naohisa Tsuchiya
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Abstract
An object of the present invention is to reduce the period of time required to stop a fuel cell system and to suppress freezing of a fuel cell. The fuel cell system includes a controller that controls operations of a fuel cell, and the controller operates the fuel cell in a dry condition according to a state quantity (e.g., impedance) of the fuel cell in operation. The controller can operate the fuel cell in a dry condition before a system stop command is issued. In addition, the controller can switch an operation of the fuel cell from a dry condition to a wet condition when a required output of the fuel cell or a vehicle speed of a vehicle equals or exceeds a predetermined value.
Claims4
A fuel cell system comprising:
- a fuel cell that can be operated in a dry condition, a normal condition and in a wet condition,
- wherein in the normal condition, the fuel cell is operated in a state where air stoichiometric ratio is set equal to or greater than 1 in order to achieve an optimal power generating efficiency,
- wherein the water content of the fuel cell is greater in the wet condition than the normal condition, and the water content of the fuel cell is greater in the normal condition than the dry condition;
- and
- a controller that controls operations of the fuel cell,
- wherein, in order to decrease the water content of the fuel cell in the normal condition, the controller is programmed to determine whether to operate the fuel cell in the dry condition before stopping a fuel cell system, and if the fuel cell is to be operated in the dry condition, the controller is further programmed to switch the fuel cell from operating in the normal condition to operating in the dry condition and thereby diminish power generating efficiency, and
- wherein during operating the fuel cell in the dry condition, the controller is further programmed to switch the fuel cell from operating in the dry condition to operating in the wet condition once a required output of the fuel cell cannot be satisfied by operating the fuel cell in the dry condition.
Dependencies are inferred from the claim text.