SIDE CHANNEL COMPRESSOR FOR A FUEL CELL SYSTEM, FUEL CELL SYSTEM, AND USE OF A SIDE CHANNEL COMPRESSOR

Abstract

The invention relates to a side channel compressor (1) for a fuel cell system (2) for delivering and/or compressing a gaseous medium, in particular hydrogen or a gas containing hydrogen, comprising a housing (3) and an impeller wheel (4) which can be driven by an electric motor and which is accommodated in the housing (3), thus forming at least one side channel (5) disposed axially in relation to the impeller wheel (4), wherein the side channel (5) is connected, via an axial gap (6) remaining between the housing (3) and the impeller wheel (4), to an annular channel (7) which is disposed radially in relation to the impeller wheel (4). According to the invention, the annular channel (7) is connected to an outlet (10) of the side channel compressor (1) via at least one housing bore (8, 9).

The invention also relates to a fuel cell system (2) having a side channel compressor (1) according to the invention, and to the use of a side channel compressor (1) according to the invention as a recirculation fan in a fuel cell system (2).

Claims

1. A side channel compressor (1) for a fuel cell system (2) for delivering and/or compressing a gaseous medium, the side channel compressor (1) comprising a housing (3) and an impeller wheel (4) which can be driven by an electric motor and which is accommodated in the housing (3), thus forming at least one side channel (5) disposed axially in relation to the impeller wheel (4), wherein the side channel (5) is connected, via an axial gap (6) remaining between the housing (3) and the impeller wheel (4), to an annular channel (7) which is disposed radially in relation to the impeller wheel (4), wherein the annular channel (7) is connected to an outlet (10) of the side channel compressor (1) via at least one housing bore (8, 9).

2. The side channel compressor (1) according to claim 1, wherein the annular channel (7) has a flow cross-section that varies in a circumferential direction.

3. The side channel compressor (1) according to claim 1, wherein the impeller wheel (4) is configured to be closed on an outer peripheral side.

4. The side channel compressor (1) according to claim 1, wherein the at least one housing bore (8) is configured as a blind hole and/or is substantially radially or tangentially aligned in relation to the impeller wheel (4).

5. The side channel compressor (1) according to claim 1, wherein the at least one housing bore (8) is connected to the outlet (10) via a further housing bore (9) having a reduced diameter compared to the at least one housing bore (8).

6. The side channel compressor (1) according to claim 1, wherein the at least one housing bore (8, 9) is disposed at a geodetically lowest point of the housing (3) in a use layer.

7. The side channel compressor (1) according to claim 1, wherein side channels (5) disposed on both sides of the impeller wheel (4) are connected to the annular channel (7) via a respective axial gap (6).

8. The side channel compressor (1) according to claim 1, wherein the impeller wheel (4) is connected to a rotor (11) of an electric motor (12).

9. A fuel cell system (2) having a side channel compressor (1) according to claim 1, wherein the side channel compressor (1) is disposed in a recirculation path (14) of the fuel cell system (2) for delivering and/or compressing anode exhaust gas of a fuel cell stack (15) of the fuel cell system (2).

10. A use of a side channel compressor (1) according to claim 1 as a recirculation fan in a fuel cell system (2).

11. The side channel compressor (1) according to claim 1, wherein the gaseous medium is hydrogen or a gas containing hydrogen.

12. The side channel compressor (1) according to claim 2, wherein the flow cross-section increases continuously in a rotational direction of the impeller wheel (4) and decreases abruptly in a region of the at least one housing bore (8, 9).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be explained in more detail in the following with reference to the accompanying drawings. The figures show:

[0021] FIG. 1 a schematic longitudinal section through a side channel compressor according to the invention,

[0022] FIG. 2 an enlarged section of FIG. 1 in the region of the annular channel,

[0023] FIG. 3 a schematic cross-section through the side channel compressor of FIG. 1, and

[0024] FIG. 4 a schematic view of a fuel cell system in a vehicle comprising a side channel compressor as the recirculation fan.

DETAILED DESCRIPTION

[0025] The side channel compressor 1 according to the invention shown in FIG. 1 comprises a housing 3 in which an impeller wheel 4 is accommodated. The impeller wheel 4 is connected to a rotor 11 of an electric motor 12, so that it is driven in a rotational motion. The side channel compressor 1 shown in FIG. 1 can in particular be used as a recirculation fan in a fuel cell system 2 (see FIG. 4).

[0026] As can in particular be seen in FIG. 2, the side channel compressor 1 comprises side channels 5 disposed on both sides of the impeller wheel 4 and an annular channel 7 which is disposed radially outward in relation to the impeller wheel 4. When the side channel compressor 1 is used as a recirculation fan in a fuel cell system 2 analogous to FIG. 4, recirculated aqueous anode gas enters the side channels 5. Due to the circulation flow prevailing there (see arrows 16) and due to the centrifugal forces (see arrow 17), the liquid water contained in the anode gas is displaced into the annular channel 7 via axial gaps 6.

[0027] Because the flow cross-section of the annular channel 7 varies in the circumferential direction, and in particularas shown in FIG. 3increases continuously towards a housing bore 8 configured as a blind hole in the direction of rotation (see arrow 13) of the impeller wheel 4, the water is supplied to the housing bore 8. Because the flow cross-section of the annular channel 7 is significantly smaller in the direction of rotation behind the housing bore 8 than before the housing bore 8, the water collects in the housing bore 8 and the flow in the annular channel 7 is abruptly decelerated. This builds up a back-pressure that prevents a return flow of water into the annular channel 7. Instead, the water is supplied to an outlet 10 to which the housing bore 8, which is designed as a blind hole, is connected via a further housing bore 9. The back-pressure allows the water to dissipate against an increased pressure level.

[0028] Because FIG. 3 shows only the side channel compressor 1 and not the installation situation of the side channel compressor 1, it cannot be seen from this figure that the housing bores 8, 9 and the outlet 10 are preferably disposed in the region of the geodetically lowest location of the side channel compressor 1. In a shutdown event, water in the side channel compressor 1 is thus supplied to the housing bores 8, 9 and the outlet 10 in a gravity-powered manner. Thus, at low outside temperatures, the impeller wheel 4 can be prevented from freezing.

[0029] As shown by way of example in FIG. 4, the side channel compressor 1 can be used in particular as a recirculation fan in a fuel cell system 2. The fuel cell system 2 of FIG. 4 serves to generate electrical energy of an electromotively driven vehicle. For this purpose, the fuel cell system 2 comprises a fuel cell stack 15, which is supplied with air as an oxidizer via a cathode path 18 and with hydrogen as a fuel via an anode path 19. The air is drawn from the environment and compressed using a compressor 20 disposed in the cathode path 18. Air exiting the fuel cell stack 15 is supplied to an exhaust turbine 21 for energy recovery. Water contained in the exhaust gas is separated and used in a humidification device 22 in order to humidify the compressed air. In order to cut off the air supply to the fuel cell stack 15 in the shutdown event, a shut-off valve 23 is disposed in the cathode path 18.

[0030] To supply hydrogen to the fuel cell stack 15, it is connected to several pressurized gas tanks 24 of a tank system for hydrogen via the anode path 19. Depleted anode gas exiting the fuel cell stack 15 is also recirculated via a recirculation path 14 and mixed with the fresh hydrogen. In the present case, the recirculation is caused both passively with the aid of a jet pump 25 disposed in the anode path 19 as well as actively with the aid of a side channel compressor 1 disposed in the recirculation path 14. In the present case, the latter is configured according to the present invention. To interrupt the hydrogen supply, a further shut-off valve 26 is disposed in the anode path 19.