Method for Reducing the Carbon Corrosion in a Fuel Cell Stack, and Motor Vehicle

Abstract

A method for reducing the carbon corrosion in a fuel cell stack of a fuel cell system includes the steps of detecting a corrosion value which is representative of the extent of the carbon corrosion probably occurring in the fuel cell stack during an inactive phase of the fuel cell stack, and initiating a protective measure for reducing the carbon corrosion in the fuel cell stack on the basis of the corrosion value.

Claims

1.-10. (canceled)

11. A method for reducing the carbon corrosion in a fuel cell stack of a fuel cell system, comprising the acts of: detecting a corrosion value in the fuel cell stack representative of a degree of carbon corrosion in the fuel cell stack during an inactive phase of the fuel cell stack; comparing the detected corrosion value to a value corresponding to a predetermined carbon corrosion threshold value; and initiating a protective measure to reduce the carbon corrosion in the fuel cell stack if the detected corrosion value exceeds the corrosion threshold value.

12. The method according to claim 11, wherein in the protective measure, a time interval until fuel is initially fed into an anode chamber of the fuel cell stack during an inactive phase of the fuel cell stack is shortened if the detected corrosion value exceeds the corrosion threshold value.

13. The method according to claim 12, wherein further feed of fuel during the inactive phase of the fuel cell system is prevented if the detected corrosion value exceeds a predetermined deactivation corrosion threshold value.

14. The method according to claim 11, further comprising the act of: detecting a leak-tightness of a cathode chamber of the fuel cell stack, wherein the leak-tightness of the cathode chamber corresponds to the detected corrosion value.

15. The method according to claim 14, wherein the leak-tightness of the cathode chamber is detected on the basis of a pressure profile after shutting-off of the cathode chamber.

16. The method according to claim 11, further comprising the act of: detecting an electrical voltage of at least one fuel cell of the fuel cell stack during feed of fuel into an anode chamber of the fuel cell stack during an inactive phase of the fuel cell stack, wherein the detected voltage corresponds to the detected corrosion value.

17. The method according to claim 11, wherein the fuel cell stack is provided in a motor vehicle, and the detected corrosion value is detected during a phase of non-use of the motor vehicle.

18. The method according to claim 11, wherein the fuel cell stack is provided in a motor vehicle, and a leak-tightness of the fuel cell stack is checked after shut-down procedures of the motor vehicle have been completed and before a control unit of the fuel cell system is deactivated.

19. The method according to claim 11, wherein the fuel cell stack is provided in a motor vehicle, and a leak-tightness of the fuel cell stack is checked while electrical power for the motor vehicle is being provided exclusively by at least one electrical energy store.

20. A motor vehicle, comprising: a fuel cell system having at least one fuel cell stack, wherein the fuel cell system is configured to detect a corrosion value in the fuel cell stack representative of a degree of carbon corrosion in the fuel cell stack during an inactive phase of the fuel cell stack; compare the detected corrosion value to a value corresponding to a predetermined carbon corrosion threshold value; and initiate a protective measure to reduce the carbon corrosion in the fuel cell stack if the detected corrosion value exceeds the corrosion threshold value.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0034] FIG. 1 shows an embodiment of a fuel cell system designed to carry out the present invention.

DETAILED DESCRIPTION OF THE DRAWING

[0035] The fuel cell stack 300 in FIG. 1 is in this case schematically divided into two parts, wherein one part jointly forms the anode chamber A and a second part jointly forms the cathode chamber K. The fuel cell stack 300 is illustrated in highly simplified form here. In reality, the fuel cell stack 300 generally comprises several hundred individual cells which each have a cathode and an anode that are separated by an ion-permeable separator.

[0036] The cathode subsystem comprises:

[0037] an oxidant conveyor 410 which draws in and compresses the oxidant (in this case air);

[0038] downstream of the oxidant conveyor 410, a charge-air cooler 420 which cools the compressed oxidant;

[0039] a bypass 460 which branches off upstream of the fuel cell stack 300 and opens into the exhaust-gas line downstream of the fuel cell stack;

[0040] a first cathode-side stack shut-off valve 430 or cathode shut-off valve, which is arranged upstream of the fuel cell stack 300; and

[0041] a second cathode-side stack shut-off valve 440, which is arranged downstream of the fuel cell stack 300.

[0042] The cathode-side stack shut-off valves 430, 440 are arranged immediately adjacent to the fuel cell stack 300. Here, an anode purge line 239 opens in between the first stack shut-off valve 430 and the fuel cell stack 300, which anode purge line in this case begins at an anode purge valve or purge valve 238.

[0043] The anode purge valve 238 is formed here at or adjacent to the water separator 232. The anode purge valve 238 may also be referred to as anode-side stack shut-off valve 238 downstream of the fuel cell stack 300.

[0044] Here, the anode subsystem furthermore comprises inter alia:

[0045] at least one fuel source (illustrated here by “H2”);

[0046] at least one anode-side (first) stack shut-off valve 211, which is arranged upstream of the fuel cell stack 300 and which is designed to shut off the fluidic connection between the fuel source and the rest of the anode subsystem;

[0047] at least one ejector 234 which is designed to introduce recirculated gas into the anode feed line; and

[0048] at least one fuel recirculation conveyor which is arranged in the recirculation line and conveys the gas for recirculation.

[0049] It is likewise possible, in particular in an embodiment without recirculation, for the anode-side stack shut-off valve 211 to be provided immediately adjacent to the anode inlet of the fuel cell stack 300.

[0050] The cathode-side stack shut-off valves 430, 440 form, together with a subregion of the fuel cell 300, a cathode chamber K which is separated in gas-tight fashion with respect to the rest of the components of the cathode subsystem. Likewise, the anode-side stack shut-off valves 211, 238 in this case form an anode chamber A together with a subregion of the fuel cell 300, which may be closed off with respect to other regions of the anode subsystem and/or of the cathode subsystem.

[0051] Not illustrated is the control unit for carrying out the method disclosed here. It is in particular a control unit which may be configured to carry out the method disclosed here even during a phase of non-use of the motor vehicle.

[0052] The above description of the present invention serves merely for illustrative purposes and not for the purposes of limiting the invention. In the context of the invention, various alterations and modifications are possible without departing from the scope of the invention and its equivalents.