1. Field of the Invention
The present invention relates to a fuel cell system.
Priority is claimed on Japanese Patent Application No. 2005-177592, filed Jun. 17, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
In a known fuel cell system having a plurality of sensors for detecting operation states of a fuel cell, when a specific sensor (e.g., an air flow rate sensor, a hydrogen inlet pressure sensor, or a cooling water inlet pressure sensor) has an abnormal state, a substitutional value with respect to a signal value output from the sensor in the abnormal state is computed based on a signal value output from another sensor (e.g., an air temperature sensor, a hydrogen outlet pressure sensor, or a cooling water outlet pressure sensor) in a normal state, and the operation of the fuel cell is continued in accordance with the computed substitutional value (see, for example, Japanese Unexamined Patent Application, First Publication No. 2004-179127).
In the fuel cell system relating to the above conventional technique, the fuel cell is operated in accordance with signal values output from the plurality of sensors, and only a substitutional value for the signal value output from a sensor in the abnormal state is computed based on a signal value output from another sensor in the normal state. Therefore, if the sensor necessary for computing the substitutional value enters an abnormal state, it is difficult to continue the operation of the fuel cell. For example, when the fuel cell system is provided for supplying electric power to a driving source of a vehicle, it may be difficult to run the vehicle.
In addition, if redundant or excessive sensors are provided for computing a substitutional value for a target sensor, the structure of the fuel cell system is complicated, thereby increasing the cost necessary for implementing the structure.