ANODE CIRCUIT

Abstract

The invention relates to an anode circuit (8) for a fuel cell (3) having at least one gas jet pump (6) for recirculating anode exhaust gas, which has at least one nozzle (18) through which the fuel gas (H 2) may flow as a fuel gas flow, and which has a fuel gas line (14), a recirculation line (7), and an outflow line (15). The anode circuit according to the invention is characterized in that a plurality of nozzles (18) with different geometries are arranged in a nozzle body (16), which is movable relative to the fuel gas line (14) in such a manner that in each case one of the nozzles (18) is selectively usable.

Claims

1. An anode circuit for a fuel cell having at least one gas jet pump for recirculating anode exhaust gas, comprising at least one nozzle through which the fuel gas is able to flow as a fuel gas flow, and which comprises a fuel gas line, a recirculation line, and an outflow line, wherein a plurality of nozzles having different geometries are arranged in a nozzle body which is movable relative to the fuel gas line such that one of the nozzles is selectively usable, respectively.

2. (canceled)

3. (canceled)

4. The anode circuit according to claim 1, wherein the fuel gas line and the outflow line are configured to be aligned.

5. The anode circuit according to claim 1, wherein the nozzle body tapers at the outer circumference thereof in the flow direction of the fuel gas flow.

6. The anode circuit according to claim 1, wherein the recirculation line is formed at an angle to the fuel gas line and/or outflow line.

7. The anode circuit according to claim 6, wherein the angle is approximately 90.

8. The anode circuit according to claim 1, characterized by its use in a fuel cell system which is to provide electric drive power in a motor vehicle.

9. The anode circuit according to claim 4, wherein the nozzle body tapers at the outer circumference thereof in the flow direction of the fuel gas flow.

10. The anode circuit according to claim 4, wherein the recirculation line is formed at an angle to the fuel gas line and/or outflow line.

11. The anode circuit according to claim 5, wherein the recirculation line is formed at an angle to the fuel gas line and/or outflow line.

12. The anode circuit according to claim 4, characterized by its use in a fuel cell system which is to provide electric drive power in a motor vehicle.

13. The anode circuit according to claim 5, characterized by its use in a fuel cell system which is to provide electric drive power in a motor vehicle.

14. The anode circuit according to claim 6, characterized by its use in a fuel cell system which is to provide electric drive power in a motor vehicle.

15. The anode circuit according to claim 7, characterized by its use in a fuel cell system which is to provide electric drive power in a motor vehicle.

Description

[0016] Here shows:

[0017] FIG. 1 a fuel cell system shown in principle in an at least partially electrically driven vehicle;

[0018] FIG. 2 a gas jet pump according to the invention in a sectional view in a first operating condition;

[0019] FIG. 3 the gas jet pump according to FIG. 2 in a second operating state; and

[0020] FIG. 4 a top view of the nozzle body used in the gas jet pump according to FIGS. 2 and 3.

[0021] The illustration in FIG. 1 schematically indicates a vehicle 1, for example a passenger vehicle or a commercial vehicle, which obtains at least some of its electric drive power from a fuel cell system designated by 2. The core of said fuel cell system 2 constitutes a fuel cell 3. Said fuel cell 3 is configured as a fuel cell stack consisting of a plurality of individual cells in a manner known in the art. Only as an example, a shared anode space 4 and a shared cathode space 5 are indicated here. The fuel cell 3 is to be configured, for example, as a PEM fuel cell. Hydrogen H.sub.2 is supplied to the fuel cell 3 from a hydrogen storage means which is not shown here, for example a pressure gas storage means. The hydrogen enters the anode space 4 of the fuel cell 3 as a fuel jet via a gas jet pump 6. Exhaust gas from the anode space 4 returns to the gas jet pump 6 via a recirculation line 7, and is taken in by the latter and fed back into the anode space 4 mixed with the fresh hydrogen. This so-called anode circuit 8 is generally known to those skilled in the art of fuel cell systems.

[0022] The anode circuit 8 may also have a water separator and/or a discharge valve 9 to discharge water and/or inert gases which accumulate in the anode circuit 8 over time from the anode circuit 8, for example from time to time or depending on the hydrogen concentration. In addition, it may include a recirculation fan as an enhancement to the gas jet pump 6, but this is not shown here similar to the water separator. Discharged gases enter an exhaust air line 11 of the fuel cell system 2 by using a line designated by 10.

[0023] Air is supplied to the cathode space 5 as an oxygen providing means via an air conveying device 12 and a gas/gas humidifier 13, which is indicated here by way of example. The exhaust air then passes through the exhaust air line 11 mentioned above, again through the gas/gas humidifier 13 into the environment. This is generally known and common practice for the one skilled in fuel cell systems. The one skilled herein also knows that other components such as charge-air-coolers, water separators, exhaust air turbines, and the like may also be provided. However, for the present invention this is of minor importance regarding the anode circuit 8, thus a detailed description thereof will be omitted.

[0024] FIG. 2 shows a cross section of the gas jet pump 6 which is schematically indicated in FIG. 1, which is referred as a jet pump. Here, a fuel gas line 14 is displayed and, in alignment hereto, an outflow line 15 configured as a Venturi tube through which the mixture of a fuel jet which is entering by the fuel gas line 14, and exhaust gas from the anode space 4 which is taken in via the recirculation line 7 flows back to the anode space 4. The particular feature of the gas jet pump 6 is a nozzle body designated by 16, which is rotatable about an axis of rotation 17, which is different from the central axis of the fuel gas line 14 and the outflow line 15 aligned hereto. A plurality of individual nozzles 18 are formed in said nozzle body 16. In the illustration of FIG. 2, a nozzle designated by 18.1 is located aligned to the fuel gas line 14 and the outflow line 15, which is provided here by way of example for an average hydrogen flow which flows to the anode space 4. The geometry thereof if configured in a way that it establishes good conditions for taking in the exhaust gas flow from the recirculation line 7 in said volume flow, in particular that a flow velocity above the speed of sound is realized, and thus the suction behavior of the gas jet pump 6 is optimized for said volume flow.

[0025] The same configuration of the gas jet pump 6 is shown again in the illustration of FIG. 3. The nozzle body 16 is correspondingly rotated about the axis of rotation 17, so that the nozzle designated by 18.1 is now arranged outside the area where the fuel gas flows, and that a nozzle designated by 18.2 for a correspondingly smaller volume flow of the dosed hydrogen has been pivoted into alignment between the fuel gas line 14 and the outflow line 15, and is now active inside the gas jet pump 6. The configuration of the nozzle body 16, which is configured as tapered in the flow direction, corresponds approximately to the drum of drum revolver, and is displayed in a top view in the illustration in FIG. 4. It may be rotated about the axis of rotation 17 accordingly, thus the nozzles 18.1-18.4, each configured with the same starting diameter matching the fuel gas line 14, process the individual volume flows in the desired manner. This means that in the exemplary embodiment shown here, four corresponding nozzles 18.1-18.4 are provided for four different orders of magnitude of volumetric flows. The configuration may be enhanced such that five, six, seven, or more individual nozzles 18 in the nozzle body 16, which is formed here in a rotationally symmetrical way, are configured, for example.

[0026] This finally results in an extraordinarily compact and efficient configuration of the gas jet pump 6, which allows a simple alignment to the dosed hydrogen flow as a fuel gas flow by pivoting the appropriate nozzle 18.1-18.4 into alignment between the fuel gas line 14 and the outflow line 15 according to the magnitude of this volume flow. This enables ideal flow conditions through the gas jet pump 6, and here in particular the part of the outflow line 15 configured as a Venturi tube, thus the best possible intake of the recirculated exhaust gas from the recirculation line 7 of the fuel cell system 2 or the anode circuit 8 is achieved by negative pressure effects and effects of impulse exchange. This is feasible without using a complex multiple piping, the use of a variety of valves and without the use of a nozzle needle.