1. Field of the Invention
The invention relates to a fuel cell system.
2. Description of Related Art
Fuel cells that generate electricity by an electrochemical reaction between a fuel gas and an oxidant gas are drawing attention as an energy source. The fuel cells are generally used in the form of a fuel cell stack obtained by stacking a plurality of unit cells. Then, in a fuel cell stack, an end plate is disposed at each of two opposite ends in the stacking direction in which the unit cells are stacked.
In a fuel cell system that includes such a fuel cell stack, a plurality of pipes for conveying the fuel gas, the oxidant gas and a cooling medium to the fuel cell stack are connected to the fuel cell stack. This piping structure is required to be compactly constructed in order to improve the ease of connecting the pipes and to reduce the size of the fuel cell system. To that end, a technology that integrates portions of the pipes that are connected to a fuel cell stack has been proposed (see, e.g., Japanese Patent Application Publication No. 2010-55867 (JP-A-2010-55867)).
A conceivable manner of constructing a compact piping structure connected to a fuel cell stack is a manner in which a fuel gas channel for conveying the fuel gas along surfaces of an end plate in a direction parallel to the surfaces, are formed in the interior of the end plate, and the end plate is integrated or consolidated with an injector that injects the fuel gas into the fuel gas channel and a relief valve for preventing overpressure in the fuel gas channel. Furthermore, in conjunction with this manner of construction, a construction in which the injector is disposed in one of the two surfaces of an end plate and the relief valve is disposed in the other surface of the end plate is conceivable. However, if an end plate is constructed as described above, the relief valve may malfunction due to the dynamic pressure of the fuel gas injected from the injector, depending on the positional relation between the injector and the relief valve.