Stop method for fuel cell system and fuel cell system

Abstract

A stop method for a fuel cell system including a fuel cell unit in which hydrogen is supplied to an anode, and air is supplied to a cathode so as to generate electrical power via an electrochemical reaction. The stop method includes the steps of stopping supply of hydrogen to the anode, electrically connecting the anode and the cathode via an electrical load, and supplying air to the anode.

Description

BACKGROUND OF THE INVENTION [0001] Priority is claimed on Japanese Patent Application No. 2003-422921, filed Dec. 19, 2003, the contents of which are incorporated herein by reference. [0002] 1. Field of the Invention [0003] The present invention relates to a stop method for a fuel cell system and a fuel cell system which are adapted for cold start-up. [0004] 2. Description of Related Art [0005] In recent years, fuel cell powered vehicles have been proposed, each of which includes a fuel cell system as a driving source of the vehicle. As a type of fuel cell system for such vehicles, a fuel cell system is known which includes a predetermined number of cell units stacked one on the other, each of which includes an anode, a cathode, and an electrolyte membrane sandwiched therebetween. When hydrogen is supplied to the anode and air (or oxygen) is supplied to the cathode, electrical power generation is performed via an electrochemical reaction of hydrogen and oxygen which is accompanied b...

AI Technical Summary

Benefits of technology

[0013] According to the above stop method for a fuel cell system, because air is supplied to the anode while not supplying hydrogen thereto upon stoppage of the fuel cell, water remaining at the anode can be discharged while significantly reducing the amount of consumed hydrogen. As a result, start-up performance of the fuel cell system can be improved due to discharge of water remaining in the gas flow paths upon stoppage of the fuel cell system.

[0026] In this case, when supply of hydrogen is stopped, by electrically connecting the anode and the cathode via the electrically powered auxiliaries, additional circuit, etc., for electrically connecting the anode and the cathode becomes unnecessary. Accordingly, the number of devices in the fuel cell system will not increase, and thereby complexity of the fuel cell system can be avoided.

Problems solved by technology

Conventionally, supplying air to the anode had a possibility of causing another problem that hydrogen and oxygen existing in the anode area produce a potential difference inside the anode, a potential difference inside the cathode, and a potential difference between the anode and the cathode, and thereby cause oxidation in the cathode area.

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