Hydrogen purging device and method for fuel cell system

Abstract

A hydrogen purging device for a fuel cell system includes a humidifier that humidifies dry air supplied from an air blower, using moist air discharged from a cathode of a stack and supplies the humidified air to the cathode. A water trap and a hydrogen recirculation blower are sequentially connected to an outlet of an anode, wherein a hydrogen outlet of the water trap and an inlet of the humidifier are connected by a cathode-hydrogen purging line for purging hydrogen to the cathode so that the hydrogen discharged from the anode of the fuel stack is purged to the cathode during idling or during normal driving.

What is claimed is: 
     
         1 . A hydrogen purging device for a fuel cell system, which includes a humidifier that humidifies dry air supplied from an air blower, using moist air discharged from a cathode of a stack and supplies the humidified air to the cathode, and a water trap and a hydrogen recirculation blower sequentially connected to an outlet of an anode,
 wherein a hydrogen outlet of the water trap and an inlet of the humidifier are connected by a cathode-hydrogen purging line for purging hydrogen to the cathode so that the hydrogen discharged from the anode of the fuel stack is purged to the cathode during idling section or during normal driving.   
     
     
         2 . The device of  claim 1 , wherein a valve that allows or stops the hydrogen purging to the cathode is disposed in the cathode-hydrogen purging line. 
     
     
         3 . A hydrogen purging method comprising:
 a first step of purging hydrogen from an anode of a fuel cell stack;   a second step of supplying the purged hydrogen to an inlet of a humidifier; and   a third step of passing the hydrogen supplied to the inlet of the humidifier through the humidifier with air and dispersing the hydrogen to the anode of the fuel cell stack.   
     
     
         4 . The method of  claim 3 , wherein the first to third steps are periodically performed during idling or during normal driving of a fuel cell vehicle. 
     
     
         5 . The method of  claim 4 , wherein hydrogen is purged to a cathode in accordance with the first to third steps when beginning idling idling section, and the hydrogen purging to the cathode is stopped in accordance with the first to third steps when a cell voltage drops to or below a reference voltage. 
     
     
         6 . The method of  claim 4 , wherein the hydrogen is purged to a cathode in accordance with the first to third steps when the amount of charge of cells is a predetermined level or more during the normal driving, and the hydrogen purging to the cathode is stopped in accordance with the first to third steps when a voltage differences of the cells are at or above a predetermined level.