Apparatus for recirculation of a cathode gas in a fuel cell arrangement, method for shutting down such a fuel cell arrangement

1. Apparatus for recirculation of a cathode gas in a fuel cell arrangement having a cathode gas supply for supplying the cathode gas to a cathode area in the fuel cell arrangement, and a cathode gas outlet for carrying partially consumed cathode gas out of the cathode area; said apparatus comprising:

a recirculation guide for recirculating at least a portion of the partially consumed cathode gas from a junction point in the cathode gas outlet into a supply point in the cathode gas supply, wherein the junction and supply points are arranged within the recirculation guide; and

first and second blocking elements arranged outside of the recirculation guide, wherein the first blocking element is arranged in a flow direction upstream of the supply point and is configured to block the cathode gas supply, and the second blocking element is arranged in a flow direction downstream from the junction point and is configured to block the cathode gas outlet, wherein the first and second blocking elements are configured such that a closed circuit for the partially consumed cathode gas is formed when the first and second blocking elements are closed; wherein,

the first and second blocking elements each comprise at least one of a valve and a restrictor;

the first and second blocking elements are self-latching;

the first and second blocking elements are driven via a worm drive; and

the first and second blocking elements are driven by a common mechanical actuator.

2. The apparatus according to claim 1 , comprising a continuous-flow machine configured to recirculate the partially consumed cathode gas when the blocking apparatus is closed.

3. The apparatus according to claim 2 , wherein the continuous-flow machine is an electrically driven turbocharger.

4. The apparatus according to claim 2 , wherein the continuous-flow machine comprises a volumetric compressor.

5. The apparatus according to claim 4 , wherein the volumetric compressor is one of a screw-type compressor and a Roots compressor.

6. The apparatus according to claim 1 , further comprising a control apparatus which is configured and located to block the blocking apparatus and to activate the continuous-flow machine in a switched-off operating mode of said fuel cell arrangement.

7. The apparatus according to claim 6 , wherein the control apparatus is configured to maintain the switched-off operating mode for a time interval that is one of preset and a function of the remaining oxygen content in the partially consumed cathode gas.

8. The apparatus according to claim 1 , comprising at least one restrictor that has a restrictor valve, the restrictor being sealed by one of i) a circumferential seal on a sealing disc of the restrictor valve, and ii) an internally rubber-coated restrictor valve housing.

9. The apparatus according to claim 1 , wherein the blocking apparatus has a pressure maintenance mechanism that is arranged in the cathode gas outlet, in the flow direction downstream from the junction point, and is configured to block the cathode gas outlet.

10. A fuel cell apparatus for a vehicle, having a recirculation apparatus according to claim 1 .

11. The apparatus according to claim 1 , wherein the partially consumed cathode gas is circulated until the residual oxygen in the cathode gas is consumed, or has fallen below a limit value.