On-board fuel cell system and method of controlling the same

Abstract

An on-board fuel cell system adapted to be installed on a motor vehicle includes a main passage connecting a hydrogen-gas storage device with an inlet of a fuel cell, a circulation passage that connects an outlet of the fuel cell with a first point in the main passage, a pump disposed in the circulation passage, and a bypass passage that connects a second point between the outlet of the storage device and the first point, with a third point located in the circulation passage between the outlet of the fuel cell and the pump. During a normal operation condition of the system, the hydrogen gas flows from the storage device to the fuel cell through the main passage, and hydrogen gas discharged from the fuel cell returns to the main passage through the circulation passage. When the pressure of the hydrogen gas is lower than a reference pressure, the pump operates to draw the hydrogen gas out of the storage device and feed the hydrogen gas from the main passage to the circulation passage through the bypass passage, and to the fuel cell through the main passage.

1 . An on-board fuel cell system adapted to be installed on a motor vehicle, comprising: 
 a hydrogen-gas storage device capable of discharging a hydrogen gas stored therein at a predetermined pressure;    a fuel cell that is supplied with the hydrogen gas discharged from the hydrogen-gas storage device, so as to generate electric power;    a passage that connects an outlet of the hydrogen-gas storage device with an inlet of the fuel cell, and allows the hydrogen gas discharged from the hydrogen-gas storage device to flow therethrough to be supplied to the fuel cell;    at least one pressure reducing device disposed in the passage to reduce a pressure of the hydrogen gas discharged from the hydrogen-gas storage device; and    a relief valve that is able to permit and inhibit a flow of gas therethrough upon opening and closing of the relief valve, respectively; and    wherein, when a pressure of the hydrogen gas in the passage between the at least one pressure reducing device and the inlet of the fuel cell is higher than a reference pressure, the relief valve is opened so that the hydrogen gas is discharged from the passage to the outside of the vehicle.    
   
   
       2 . An on-board fuel cell system adapted to be installed on a motor vehicle, comprising: 
 a hydrogen-gas storage device capable of discharging a hydrogen gas stored therein at a predetermined pressure;    a fuel cell that is supplied with the hydrogen gas discharged from the hydrogen-gas storage device, so as to generate electric power;    a first passage that connects an outlet of the hydrogen-gas storage device with an inlet of the fuel cell, and allows the hydrogen gas discharged from the hydrogen-gas storage device to flow therethrough to be supplied to the fuel cell;    at least one pressure reducing device disposed in the first passage to reduce a pressure of the hydrogen gas discharged from the hydrogen-gas storage device;    a second passage that extends from a particular point located in the first passage between the at least one pressure reducing device and the inlet of the fuel cell, toward an outside of the vehicle; and    a relief valve that is disposed in the second passage, and is able to permit and inhibit flow of gas therethrough upon opening and closing thereof, respectively,    wherein when a pressure of the hydrogen gas that exists, in the second passage, between the relief valve and the particular point, is higher than a reference pressure, the relief valve is opened so that the hydrogen gas is discharged from the first passage to the outside of the vehicle through the second passage.    
   
   
       3 . The on-board fuel cell system according to  claim 2 , wherein an outlet of the second passage is positioned such that the hydrogen gas discharged from the second passage is directed toward a road surface.  
   
   
       4 . The on-board fuel cell system according to  claim 2 , wherein the hydrogen-gas storage device is a high pressure hydrogen gas tank.  
   
   
       5 . An on-board fuel cell system adapted to be installed on a motor vehicle, comprising: 
 a hydrogen-gas storage device capable of discharging a hydrogen gas stored therein at a predetermined pressure;    a fuel cell that is supplied with the hydrogen gas discharged from the hydrogen-gas storage device, so as to generate electric power;    a first passage that connects an outlet of the hydrogen-gas storage device with an inlet of the fuel cell, and allows the hydrogen gas discharged from the hydrogen-gas storage device to flow therethrough to be supplied to the fuel cell;    at least one pressure reducing device disposed in the first passage to reduce a pressure of the hydrogen gas discharged from the hydrogen-gas storage device;    a relief valve that is able to permit and inhibit a flow of gas therethrough from the first passage to the outside of the vehicle, upon the respective opening and closing of the relief valve; and    a passage portion which is closer to a particular point in the first passage than is the location of the relief valve, the particular point being located between the at least one pressure reducing device and the inlet of the fuel cell,    wherein when a pressure of the hydrogen gas in the passage portion is higher than a reference pressure, the relief valve is opened so that the hydrogen gas is discharged from the particular point in the first passage to the outside of the vehicle.