Fuel cell system

1. A fuel cell system comprising: a fuel cell stack; a hydrogen-gas supply device configured to supply hydrogen gas filled in a hydrogen tank into the fuel cell stack along with pressure reduction of the hydrogen gas; an air supply duct configured to supply air into the fuel cell stack; and an air exhaust duct configured to exhaust surplus air from the fuel cell stack, the fuel cell system, wherein

the hydrogen-gas supply device is disposed inside a heat exchange chamber capable of communicating with the air supply duct and the air exhaust duct,

the air exhausted from the fuel cell stack is introduced into the heat exchange chamber when a temperature of the hydrogen-gas supply device reaches or falls below a predetermined temperature, and

air introduced into the heat exchange chamber and cooled down by the hydrogen-gas supply device is supplied into the fuel cell stack when a temperature of the air exhausted from the fuel cell stack reaches or exceeds a predetermined temperature.

2. The fuel cell system according to claim 1 , wherein the fuel cell stack is an air-cooled fuel cell stack using air as both a reactant gas and a cooling medium.

3. The fuel cell system according to claim 1 , wherein

the heat exchange chamber includes: a first switch valve for opening and closing a first communication part communicating with the air supply duct; a second switch valve for opening and closing a second communication part communicating with the air exhaust duct; and a third communication part communicating with an outside at an upstream portion of the heat exchange chamber in a direction of a flow of the hydrogen gas, and

an air blowing fan capable of switching an air blowing direction thereof is arranged in the third communication part.

4. The fuel cell system according to claim 3 , wherein

a temperature sensor configured to detect a temperature of air is arranged in each of the air supply duct and the air exhaust duct,

a temperature sensor configured to detect a temperature of the hydrogen tank is arranged in the hydrogen-gas supply device, and

the first switch valve, the second switch valve, and the air blowing fan are operated selectively based on the temperatures detected by the temperature sensors.

5. The fuel cell system according to claim 4 , wherein in a case of filling hydrogen gas into the hydrogen tank, at least one of the first switch valve and the second switch valve is opened and the ambient air is introduced into the heat exchange chamber by means of the air blowing fan when the temperature of the hydrogen tank reaches or exceeds a predetermined value.

6. The fuel cell system according to claim 3 , wherein

a hydrogen purge pipe for exhausting surplus hydrogen gas is connected to the fuel cell stack, and

a downstream end portion of the hydrogen purge pipe is connected to the air exhaust duct at a portion downstream of the second communication part in a direction of a flow of the air in the air exhaust duct.

7. The fuel cell system according to claim 3 , wherein the air blowing fan has an explosion-proof structure.

8. The fuel cell system according to claim 1 , wherein

the heat exchange chamber includes a hydrogen-gas concentration sensor configured to detect a hydrogen-gas concentration therein, and

ambient air is introduced into the heat exchange chamber and flowed into the air exhaust duct when the hydrogen-gas concentration detected by the hydrogen-gas concentration sensor reaches or exceeds a predetermined concentration.

9. The fuel cell system according to claim 1 , wherein

the heat exchange chamber includes a lower chamber part in such a cross-sectional shape as to be open on an upper side, and an upper chamber part for closing the opening in the lower chamber part, and

the upper chamber part is formed by a floor of a vehicle.