FUEL CELL SYSTEM WITH A VIBRATION GENERATOR, AND METHOD FOR OPERATING A FUEL CELL SYSTEM WITH A VIBRATION GENERATOR

Abstract

A fuel cell system (200), wherein the fuel cell system (200) has: a) a fuel cell stack (10), b) an anode gas path (20) which fluidically communicates with the fuel cell stack (10) and which serves for supplying anode gas from an anode gas store (22) to the fuel cell stack (10), c) a cathode gas path (30) which fluidically communicates with the fuel cell stack (10) and which serves for supplying cathode gas from a cathode gas store (32) to the fuel cell stack (10), d) a cooling fluid path (40) which fluidically communicates with the fuel cell stack (10) and which serves for supplying cooling fluid from a cooling fluid store (42) to the fuel cell stack (10), e) a vibration generator (60) which is in data-transmitting communication with a control unit (50) and which serves for setting the fuel cell stack (10) into a vibrating state, and f) the control unit (50) for actuating the vibration generator (60) in order to set the fuel cell stack (10) into the vibrating state by means of the vibration generator (60).

Claims

1. A fuel cell system (200), wherein the fuel cell system (200) comprises: a) a fuel cell stack (10), b) an anode gas pathway (20) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with anode gas from an anode gas reservoir (22), c) a cathode gas pathway (30) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with cathode gas from a cathode gas reservoir (32), d) a cooling fluid pathway (40) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with cooling fluid from a cooling fluid reservoir (42), e) a vibration generator (60) for setting the fuel cell stack (10) in a vibrating state, and f) a control unit (50) in data communication with the vibration generator (60) and for actuating the vibration generator (60), in order to set the fuel cell stack (10) in the vibrating state by means of the vibration generator (60).

2. The fuel cell system (200) as claimed in claim 1, wherein the fuel cell system (200) comprises, as the vibration generator (60), a voltage transformer (62) in electrical communication with the fuel cell stack (10) for conversion of the output voltage of the fuel cell stack (10), where the voltage transformer (62) is designed for actuation upstream of the control unit (50) in such a way that the fuel cell stack (10) can be set in the vibrating state by drawing of a pulsed current by the voltage transformer (62) from the fuel cell stack (10).

3. The fuel cell system (200) as claimed in claim 1, wherein the fuel cell system (200) comprises, as vibration generator (60), a component (64) of the anode gas pathway (20) and/or of the cathode gas pathway (30) and/or of the cooling fluid pathway (40) for control of the flow of the anode gas and/or of the cathode gas and/or of the cooling fluid, where the component (64) is designed to be actuated by the control unit (50) in such a way that the component (64) is switchable between at least a first switching state and a second switching state, such that the fuel cell stack (10) can be set in the vibrating state by the switching of the component (64).

4. The fuel cell system (200) as claimed in claim 3, wherein the component (64) is one of the following components: a valve, a compressor.

5. The fuel cell system (200) as claimed in claim 1, wherein the fuel cell system (200), as vibration generator (60), comprises a knocker component (66) disposed on the fuel cell stack (10) for impacting with the fuel cell stack (10), wherein the knocker component (66) is mechanically connected to the fuel cell stack (10) and is designed to be actuated by the control unit (50) in such a way that the fuel cell stack (10) is set in the vibrating state by the impacting with the fuel cell stack (10).

6. The fuel cell system (200) as claimed in claim 1, wherein the fuel cell system (200) has a water content sensor (202) in data communication with the control unit (50) for ascertaining the water content of the fuel cell stack (10), and in that the control unit (50) of the fuel cell system (200) is also designed to control the vibration generator (60) for setting the fuel cell stack (10) in the vibrating state as a function of the water content of the fuel cell stack (10) ascertained by the water content sensor (202).

7. A method of operating a fuel cell system (200) that includes a fuel cell stack (10), an anode gas pathway (20) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with anode gas from an anode gas reservoir (22), a cathode gas pathway (30) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with cathode gas from a cathode gas reservoir (32), a cooling fluid pathway (40) in fluid communication with the fuel cell stack (10) for supply of the fuel cell stack (10) with cooling fluid from a cooling fluid reservoir (42), a vibration generator (60) for setting the fuel cell stack (10) in a vibrating state, and a control unit (50) in data communication with the vibration generator (60) and for actuating the vibration generator (60), in order to set the fuel cell stack (10) in the vibrating state by means of the vibration generator (60), the method comprising the following steps: a) actuating (300) the vibration generator (60) by means of the control unit (50), b) setting (302) the fuel cell stack (10) in the vibrating state by means of the vibration generator (60).

8. The method as claimed in claim 7, wherein the control unit (50) actuates (310) a voltage transformer (62), and the voltage transformer (62) draws current (311) in pulsed form from the fuel cell stack (10), such that the drawing of pulsed current sets (302) the fuel cell stack (10) in the vibrating state.

9. The method as claimed in claim 7, wherein the control unit (50) actuates (320) a component (64) of the anode gas pathway (20) and/or of the cathode gas pathway (30) and/or of the cooling fluid pathway (40) for control of the flow of the anode gas and/or of the cathode gas and/or of the cooling fluid, and the component (64) is switched (321) between at least a first switching state and a second switching state, such that the switching sets (302) the fuel cell stack (10) in the vibrating state.

10. The method as claimed in claim 7 in conjunction with a fuel cell system (200), wherein the control unit (50) actuates (330) a knocker component (66) disposed on the fuel cell stack (10) for impacting with the fuel cell stack (10) and the knocker component (66) impacts with (331) the fuel cell stack (10), such that the impacting sets (302) the fuel cell stack (10) in the vibrating state.

11. The method as claimed in claim 7, wherein a water content sensor (202) ascertains (350) the water content of the fuel cell stack (10) and communicates it (351) to the control unit (50), wherein the control unit (50) controls (352) the actuating (300) of the vibration generator (60) and the setting (302) of the fuel cell stack (10) in the vibrating state by means of the vibration generator (60) depending on the water content ascertained by the water content sensor (202).

12. The method as claimed in claim 7, wherein the vibration generator (60) sets (302) the fuel cell stack (10) in the vibrating state with a frequency of 500 Hz to 50 kHz, especially with a frequency of 16 kHz to 25 kHz.

13. The method as claimed in claim 7, wherein the vibration generator (60) sets (302) the fuel cell stack (10) in the vibrating state with a frequency of 50 Hz to 200 kHz.

14. The method as claimed in claim 7, wherein the vibration generator (60) sets (302) the fuel cell stack (10) in the vibrating state at particular time intervals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The figures show, in schematic form:

[0051] FIG. 1 a fuel cell system of the invention with a vibration generator,

[0052] FIG. 2a fuel cell system of the invention with a DC-DC transformer as vibration generator,

[0053] FIG. 3a fuel cell system of the invention with a valve as vibration generator,

[0054] FIG. 4a fuel cell system of the invention with multiple components as vibration generators,

[0055] FIG. 5a fuel cell system of the invention with a knocker component as vibration generator,

[0056] FIG. 6a fuel cell system of the invention with a water content sensor,

[0057] FIG. 7a method of the invention,

[0058] FIG. 8a method of the invention, and

[0059] FIG. 9a method of the invention.

[0060] In the figures that follow, identical reference numerals are used even by different working examples of the same technical features.

DETAILED DESCRIPTION

[0061] FIGS. 1 to 6 show various embodiments of an inventive fuel cell system 200. In FIGS. 1 to 6, a fuel cell stack 10 is connected by means of an anode gas pathway 20 to an anode gas reservoir 22, by means of a cathode gas pathway 30 to a cathode gas reservoir 32, and by means of a cooling fluid pathway 40 to a cooling fluid reservoir 42. In this way, the fuel cell stack 10 is supplied with anode gas, cathode gas and cooling fluid. During the operation of the fuel cell system 200, hydrogen molecules that have been split at the catalyst layer to give protons migrate from an anode side of a fuel cell of the fuel cell system 200 to a cathode side, in order to combine with the reduced oxygen molecules to give water molecules. These water molecules can combine, for example, to give water droplets and make channels of a gas diffusion layer and/or channels of a bipolar plate impervious to fluid. Wires for data communication, for example an electrical wire, for the sake of clarity, may be illustrated by a dashed and dotted line.

[0062] Moreover, FIG. 1 shows a control unit 50 that actuates a vibration generator 60. If the vibration generator 60 is actuated by the control unit 50, the vibration generator 60 sets the fuel cell stack 10 in a vibrating state. A vibrating state may be understood to mean a state of the fuel cell stack 10 in which it performs vibrations owing to the vibration generator 60. The vibration generator 60 can especially set bipolar plates and/or membranes and/or gas diffusion layers of the fuel cell stack 10 in the vibrating state. The vibration generator 60 can also cause the anode gas and/or the cathode gas and/or the cooling fluid to vibrate, and hence set the fuel cell stack 10 in the vibrating state. The setting of the fuel cell stack 10 in the vibrating state allows excess water, for example, to be discharged from the gas diffusion layers of the fuel cells of the fuel cell stack 10. The inventive fuel cell system 200 can therefore ensure efficient, uniform and undisrupted operation of the fuel cell system 200 in a particularly simple, inexpensive, safe and reliable manner. Moreover, the lifetime of the fuel cell system 200 can be prolonged.

[0063] FIG. 2 shows a working example of a fuel cell system 200 having a control unit 50, wherein the control unit is connected to a DC-DC transformer 62 and actuates the DC-DC transformer 62 in order to set the fuel cell stack 10 in a vibrating state. The DC-DC transformer 62 is connected by electrical wires to the fuel cell stack 10 and can convert the DC output voltage of the fuel cell stack 10 to a DC voltage compatible for a battery of a motor vehicle. The DC-DC transformer may also be connected to a battery (not shown). The control unit 50 actuates the DC-DC transformer in such a way that it draws in a pulsed manner from the fuel cell stack 10. This pulsed withdrawal of current allows the fuel cell stack 10, especially the bipolar plates and/or gas diffusion layers and/or membranes of the fuel cell stack 10, to be set in the vibrating state. Advantageously, the pulsed drawing of current can be effected with a frequency of 20 kHz.

[0064] The embodiment in FIG. 3 shows a control unit 50 which actuates a component of an anode gas pathway, for example a valve 64. The valve 64 is actuated by the control unit 50 in such a way that the valve 64 is switched between at least a first switching state and a second switching state, especially repeatedly switched back and forth. This alters the flow of the anode gas in the anode gas pathway, and the anode gas can be caused to vibrate. These vibrations can propagate in the direction in the anode gas pathway 20 toward the fuel cell stack 10, and set the fuel cell stack 10, especially bipolar plates, gas diffusion layers and membranes, in the vibrating state. Advantageously, a valve is used in the direct proximity of the fuel cell stack 10, such that the vibrations of the anode gas undergo a minimum level of damping.

[0065] In the embodiment in FIG. 4, a control unit 50 as in FIG. 3 controls a component 64.1 of the anode gas pathway, and additionally a component 64.3 of the cathode gas pathway and a component of the cooling fluid pathway 64.2. The fuel cell system 200 consequently has multiple vibration generators 60. It is possible here for the component 64.1 in the anode gas pathway to be a recirculation pump, the component 64.3 in the cathode gas pathway to be an air compressor, and the component 64.2 to be a valve. The fuel cell stack 10 may be set in a vibrating state by any individual vibration generator 64.1, 64.2 and 64.3. The vibration generators 64.1, 64.2 and 64.3 are advantageously actuated synchronously by the control unit 50. In other words, the vibrating states are additive, and the fuel cell system 10 experiences an enhanced vibrating state. The energy expenditure of each vibration generator 60 can thus be reduced, and the components of any pathway are subjected only to minor stress.

[0066] FIG. 5 shows, in a further embodiment, a fuel cell system 200 with a knocker component 66 which is actuated by a control unit 50. The knocker component 50 is disposed on a fuel cell stack 10 and preferably impacts with bipolar plates of the fuel cell stack 10. The knocker component 66 may be an actuator which is actuated via the control unit 50 and performs mechanical movements as impacts. Proceeding from the bipolar plates, it is thus particularly advantageously also possible to set other components of the fuel cell stack 10, such as membranes and/or gas diffusion layers, in the vibrating state.

[0067] FIG. 6 shows an embodiment of a fuel cell system 200 with a water content sensor 202. The water content sensor 200 is disposed in the fuel cell stack 10 and ascertains the water content of the fuel cell stack 10, especially of gas diffusion layers and/or of membranes. Moreover, the water content sensor 202 is connected to a control unit 50 and transmits the water content of the fuel cell stack to the control unit 50. The control unit 50 is also connected to a vibration generator 60. Depending on the water content ascertained by the water content sensor 202, the control unit 50 can actuate the vibration generator in such a way that there is an appropriate water content in the fuel cell stack 10. This means that essentially no and especially no channels of bipolar plates and/or of gas diffusion layers are impermeable to fluid, i.e. blocked. It is thus ensured that the anode gas and cathode gas can flow freely and enter into chemical reactions in the fuel cell stack 10. If the water content sensor 202 ascertains an excessively high water content, the fuel cell stack 10 can, for example, be set in a vibrating state with elevated frequency and/or amplitude.

[0068] FIG. 7 shows a method of the invention wherein, in the method, a vibration generator 60 is actuated 300 by means of a control unit 50, and hence a fuel cell stack 10 is set 302 in the vibrating state by means of the vibration generator 60.

[0069] FIG. 8 shows a method of the invention wherein a control unit 50 actuates 310, 320, 330 a voltage transformer 62 or the component 64 or the knocker component 66, and the voltage transformer 62 or component 64 or knocker component 66 draws 311 current in a pulsed manner from the fuel cell stack 10, or is switched 321 between at least a first switching state and a second switching state, or impacts 331 with the fuel cell stack 10, such that the fuel cell stack 10 is set 302 in the vibrating state.

[0070] FIG. 9 shows a method of the invention wherein a water content sensor 202 ascertains 350 the water content of a fuel cell stack 10 and communicates it 351 to a control unit 50, wherein the control unit 50 controls 352 actuating 300 of a vibration generator 60 by means of the control unit 50 and setting 302 of the fuel cell stack 10 in a vibrating state by means of the vibration generator 60, depending on the water content ascertained by the water content sensor 202.