Patent ID: 8541139

Claim:
A humidifier for a fuel cell, the humidifier comprising: a main humidifier that humidifies the air supplied to a cathode of the fuel cell stack; an auxiliary humidifier that humidifies the air together with the main humidifier; and a controller configured to operate the auxiliary humidifier; wherein the auxiliary humidifier includes: an inlet assembly provided in an air exhaust pipe, through which water-supersaturated exhaust gas is discharged from a fuel cell stack, to supply water condensed from the exhaust gas to the fuel cell stack, an outlet assembly provided in an air supply pipe, through which a reactant gas to be humidified and supplied to the fuel cell stack passes, to supply the water transferred through a pumping pipe to the air supply pipe such that the reactant gas is humidified, and the pumping pipe including a porous material disposed therein and electrodes for applying a voltage to both ends of the porous material and disposed between the inlet assembly and the outlet assembly such that the water is transferred through a capillary path in the porous material with a pumping force by electroosmosis when the electrodes apply a voltage, wherein the inlet assembly of the auxiliary humidifier is provided in the air exhaust pipe connected to a cathode outlet of the fuel cell stack and the outlet assembly of the auxiliary humidifier is provided in the air supply pipe connected to a cathode inlet of the fuel cell stack to humidify the air supplied to a cathode of the fuel cell stack, wherein the outlet assembly is provided in the air exhaust pipe in front or rear of the main humidifier for humidifying the air supplied to the cathode of the fuel cell stack, and wherein the controller applies a control signal that operates the auxiliary humidifier by applying a voltage to the electrodes when a humidification load exceeds a capacity of the humidification according to operating conditions of the main humidifier.