Patent ID: 7390585
Filing Date: 2008-06-24
Classification: H01M,Y02E

Abstract:
1. A fuel cell system having a fuel cell for generating electric power using fuel gas and oxygen-bearing gas, comprising: a humidifying device for humidifying at least one of the fuel gas and oxygen-bearing gas which are supplied to the fuel cell; a water tank for storing water used in the humidifying performed by the humidifying device; a water passage through which water from the water tank flows to the humidifying device; wherein the water passage is provided with a base portion, an apex portion which is positioned higher than the base portion, and an orthogonal portion which is higher than the base portion and connects the base portion and the apex portion; a water removing device for supplying purge gas to the water passage so as to remove the water in the water passage; the water removing device comprising a supply port which is supplied with purge gas and is disposed on the apex portion; a water recirculating device for enabling the passage of water through the water passage, the water recirculating device being disposed on the water passage; a shutoff valve for blocking the water passage such that water from the water tank does not flow into the water recirculating device, the shutoff valve being provided between the water tank and the water recirculating device; a water suction outlet for introducing water from the water tank into the water passage, wherein the water suction outlet is connected to the base portion of the water passage, the base portion being positioned at the substantially same level as the water suction outlet; the shutoff valve being disposed in a higher position than the water suction outlet; a purge gas releasing device for releasing purge gas from the water passage, the purge gas releasing device connecting to the apex portion of the water passage and comprising a release pipe through which purge gas flows and a gas release valve positioned on the release pipe; a water passage temperature sensor for measuring a temperature of the water in the water passage further toward the water tank side than the shutoff valve; a purge gas release pipe temperature sensor disposed in the vicinity of the purge gas release valve; and a controller which is electrically connected to the water removing device, water recirculating device, shutoff valve, the purge gas releasing device, the water passage temperature sensor and the purge gas release pipe temperature sensor, so as to control shutdown and startup operations of the fuel cell system, the controller functioning to: control the shutoff valve to open and control the water removing device to start a supply of purge gas to the water passage when a shutdown operation of the fuel cell system begins; control the shutoff valve to block the water passage after a predetermined time period has elapsed following the start of the supply of purge gas and control the water removing device to halt the supply of purge gas after the water passage has been blocked by the shutoff valve; whereby purge gas is sealed between the shutoff valve and the water surface of the water which returns to the water passage from the water tank after the shutoff valve has blocked the water passage; control the purge gas releasing device to release purge gas from the water passage when a startup operation of the fuel cell system begins; compare a temperature detected by the purge gas pipe temperature sensor with a temperature detected by the water passage temperature sensor; and stop the release of purge gas by the purge gas releasing device when it is determined that the temperature detected by the purge gas pipe temperature sensor and the temperature detected by the water passage temperature sensor are substantially equal.