Fuel cell system and method for switching off a fuel cell stack

Patent metadata

Field	Value
Publication number	US-2017317364-A1
Application number	US-201515520818-A
Country	US
Kind code	A1
Filing date	Sep 30, 2015
Priority date	Oct 21, 2014
Publication date	Nov 2, 2017
Grant date	—

Abstract

The invention relates to a fuel cell system ( 100 ) comprising a fuel cell stack ( 10 ) comprising anode chambers ( 11 ) and cathode chambers ( 12 ), an anode supply ( 20 ) comprising an anode supply path ( 21 ) for supplying an anode operating gas to the anode chambers ( 11 ), and an anode exhaust path ( 22 ) for discharging an anode exhaust gas from the anode chambers ( 11 ), and a cathode supply ( 30 ) comprising a cathode supply path ( 31 ) for supplying a cathode operating gas to the cathode chambers ( 12 ) and a cathode exhaust path ( 32 ) for discharging a cathode exhaust gas from the cathode chambers ( 12 ), and comprising a negative-pressure generation means ( 40 ) for generating a negative pressure in the cathode chambers ( 12 ). It is provided that the negative-pressure generation means ( 40 ) is designed as an ejector which is connected to a compressor ( 33 ) arranged in the cathode supply path ( 31 ) on the pressure input side, and to the cathode chambers ( 12 ) of the fuel cell stack ( 10 ) on the suction side, in a fluid-conducting manner.

First claim

1 . A fuel cell system, comprising:
a fuel cell stack including anode chambers and cathode chambers; an anode supply including an anode supply path for supplying an anode operating gas to the anode chambers and an anode exhaust path for discharging an anode exhaust gas from the anode chambers; and a cathode supply including a cathode supply path for supplying a cathode operating gas to the cathode chambers and a cathode exhaust path for discharging a cathode exhaust gas from the cathode chambers, and including an ejector for generating a negative pressure in the cathode chambers; wherein the ejector is connected in a fluid-conducting manner on a pressure input side to a compressor arranged in the cathode supply path, on an output side to the cathode exhaust path, and on a suction side to the cathode chambers of the fuel cell stack.

2 . (canceled)

3 . The fuel cell system according to claim 1 wherein the cathode supply includes a turbine arranged in the cathode exhaust path and the ejector is connected in a fluid-conducting manner on the output side to the cathode exhaust path on the low-pressure side of the turbine.

4 . The fuel cell system according to claim 1 wherein the fuel cell system furthermore includes a flushing line, which branches off from the anode supply path or the anode exhaust path and leads to the cathode supply path or the cathode exhaust path.

5 . The fuel cell system according to claim 1 wherein the fuel cell system furthermore includes a valve for regulating a gas mass flow, the valve is arranged upstream of the suction side of the ejector.

6 . The fuel cell system according to claim 1 wherein the cathode supply includes a wastegate line that connects the cathode supply path to the cathode exhaust path, and the ejector is arranged in the wastegate.

7 . The fuel cell system according to claim 1 wherein the ejector is arranged in the cathode exhaust path.

8 . A method, comprising:
switching off a fuel cell stack of a fuel cell system, the switching including: separating cathode chambers of the fuel cell stack from an environments; generating a negative pressure in the cathode chambers in order to remove a cathode operating gas from the cathode chambers by an ejector; and introducing a fuel into the cathode chambers in order to react the fuel with residual oxygen present in the cathode chambers.

9 . The method according to claim 8 wherein the ejector is operated by a compressed cathode operating gas as propellant.

10 . The method according to claim 8 , wherein an overpressure prevailing in the cathode chambers is reduced by discharging the cathode operating gas, in particular to ambient pressure, prior to separating the cathode chambers from the environment.

11 . A fuel cell system, comprising:
a cathode chamber; a cathode supply path coupled to the cathode chamber to supply a cathode operating gas to the cathode chamber; a compressor coupled to the cathode supply path to compress the cathode operating gas within the cathode supply path; and an ejector having a pressure input connector coupled to the cathode supply path and a suction input connector coupled to the cathode chamber such that compressed cathode operating gas travelling through the ejector can draw a vacuum in the cathode chamber.

12 . The fuel cell system of claim 11 , further comprising:
an anode chamber; and a fuel flushing path coupled to the anode chamber and to the cathode chamber.

Assignees

• Volkswagen Ag

Inventors

• Lucas Christian
• Ermatschenko Natalja
• Grundei Daniel

Classifications

• H01M8/04228

  during shut-down · CPC title

• H01M8/04111

  using a compressor turbine assembly · CPC title

• H01M8/04231 Primary

  Purging of the reactants · CPC title

• H01M8/04201

  Reactant storage and supply, e.g. means for feeding, pipes · CPC title

• H01M8/04179

  by purging or increasing flow or pressure of reactants · CPC title