Centrifugal compressor for a fuel cell system

Abstract

A centrifugal compressor (10, 50) for a fuel cell system, comprising: a compressor housing (11, 51, 105), a compressor shaft (12), and a bearing arrangement comprising an axial foil bearing (15), wherein the compressor shaft (12) is axially mounted in the compressor housing (11, 51, 105) via the axial foil bearing (15), wherein the compressor housing (11, 51, 105) comprises at least one integrally formed first cooling channel (25, 53, 102) and wherein the axial foil bearing (15) comprises a bearing disk (17, 52, 108) having at least one integrally formed second cooling channel (28, 54, 103, 104) for supplying cooling air for the axial foil bearing (15), wherein the first cooling channel (25, 53, 102) is in fluidic contact with the second cooling channel (28, 54, 103, 104) such that cooling air flows from the first cooling channel (25, 53, 102) to the second cooling channel (28, 54, 103, 104).

Description

[0001] Description

[0002] title

[0003] Radial compressor for a fuel cell system

[0004] The present invention relates to a radial compressor for a fuel cell system, a fuel cell system, a method for manufacturing a compressor housing or a bearing disk for such a radial compressor, and the use of a compressor housing and / or a bearing disk in such a radial compressor and / or in such a fuel cell system.

[0005] State of the art

[0006] Compressors for fuel cell systems are generally known from the prior art. Fuel cell systems require a cathode-side air supply to maintain the chemical reaction within the fuel cell. This air supply is provided by one or more compressors. Depending on the fuel cell's power output, corresponding airflows are required, which are conveyed by the compressor. Friction in this process generates heat, which accelerates wear.

[0007] Disclosure of the invention

[0008] According to a first aspect of the present disclosure, a radial compressor for a fuel cell system is provided, comprising a compressor housing, a compressor shaft and a bearing arrangement comprising an axial foil bearing, wherein the compressor shaft is axially supported in the compressor housing via the axial foil bearing, wherein the compressor housing comprises at least one integrally formed first cooling channel and wherein the axial foil bearing comprises a bearing disk with at least one integrally formed second cooling channel for supplying cooling air to the axial foil bearing, wherein the first cooling channel is in fluidic contact with the second cooling channel, such that cooling air flows from the first cooling channel to the second cooling channel.

[0009] The term fuel cell system, as used here, refers to a fuel cell for generating electricity and / or heat. The fuel cell preferably comprises a plurality of cells connected in series. In this context, the fuel cell is preferably a solid oxide fuel cell. The fuel cell system is preferably used as a fuel cell electric drive for an electrically powered vehicle. The fuel cell system preferably uses hydrogen as the energy carrier. A so-called fuel cell stack generates the electrical energy that the vehicle requires for movement.

[0010] In this context, the term radial compressor refers to an electric radial compressor that supplies the cathode of the fuel cell with oxygen or air. The air is drawn in from the environment and supplied to the fuel cell at the required pressure for power generation. The electric radial compressor preferably comprises a compressor wheel (turbine).

[0011] The term compressor housing refers to the enclosure containing the compressor components, such as the compressor shaft, stator, rotor, etc. The compressor housing can be a single piece or multiple pieces. It may have a circumferential rib in which the first cooling channel is located.

[0012] The term compressor shaft, in this context, refers to a drive shaft on which a rotor of an electric motor drive and a compressor wheel are mounted. The compressor shaft is preferably supported by a thrust bearing and a radial bearing. The term bearing arrangement, in this context, refers to a bearing arrangement for supporting the compressor shaft in the compressor housing. The bearing arrangement preferably comprises a thrust bearing and a radial bearing.

[0013] In this context, the term "cooling channel" refers to a flow channel through which cooling air flows, intended for cooling the axial foil bearing. The cooling channel can be supplied with cooling air, in particular via a compressed air supply. The compressed air can, for example, be taken from the stream of compressed ambient air for the fuel cell. Alternatively, the compressed air can originate from another compressed air source. The compressed air can also be cooled. This cooling can be achieved, for example, via a water cooling system located within the compressor housing. Compressed air can be introduced into the compressor housing via an interface and directed to the first cooling channel, which is integrally integrated within the compressor housing. The term "cooling channel" preferably refers to a channel integrated within a bearing disk or a compressor housing. The compressor housing may, for this purpose, have a circumferential web.The circumferential web can be in contact with a bearing disc or a flange plate.

[0014] The term "integrally formed" means in this case that the cooling channel is part of the bearing disc or the compressor housing and not a separate channel of another component.

[0015] The term "bearing disc" refers to a disc that is rigidly connected to the compressor housing or a flange plate and on whose surface a film of the axial foil bearing is arranged. The integrally formed second cooling channel can be located in the bearing disc that is arranged on the bearing flange. Preferably, the integrally formed cooling channel is located in the bearing disc that is arranged on the compressor housing. For this purpose, the bearing disc can have a circumferential web that extends perpendicular to an end face of the bearing disc. The circumferential web can be in contact with a second bearing disc. The term "axial foil bearing" preferably refers to a hydrodynamic axial foil bearing.The axial foil bearing comprises a first bearing disk with a first foil arranged on it and a second bearing disk with a second foil arranged on it. The foil can be made of copper, aluminum, or steel. The axial foil bearing further includes a rotating disk that is rigidly connected to a compressor shaft. During operation, an air film or gas film forms between the rotating disk and the first foil, as well as between the rotating disk and the second foil, which carries the axial load.

[0016] In this context, the term "cooling air supply" means that compressed air or cooled compressed air is supplied to the axial foil bearing, thus reducing the temperature in the axial foil bearing.

[0017] The invention is based on the finding that axial foil bearings used for the axial support of the compressor shaft run hot during operation and thus wear out more quickly. To cool the axial foil bearing, a first cooling channel in the compressor housing and a

[0018] A second cooling channel is integrally integrated into one of the axial foil bearing's bearing discs to direct a cooling airflow into the bearing. This has a beneficial effect on the radial compressor's service life and efficiency. By arranging the first cooling channel in the compressor housing and one of the bearing discs, an expensive air distribution ring is eliminated. The cooling function is thus integrated into the compressor housing and the bearing disc. This results in overall benefits for the radial compressor's efficiency and operating costs.

[0019] According to a preferred embodiment, in a radial compressor, the first cooling channel can have a cross-section whose circumference is completely enclosed by the compressor housing, and / or the second cooling channel can have a cross-section whose circumference is completely enclosed by the bearing disk. In other words, with the exception of an inlet and an outlet, the first and second cooling channels have no areas open to the environment and are completely confined by the compressor housing or the bearing disk.

[0020] In this way, the cooling airflow can be designed efficiently and reliably. No separate arrangement of additional components, as required with partial enclosures, is necessary to implement the cooling duct routing.

[0021] According to a preferred further development, in a radial compressor the first cooling channel can have a cooling channel cross-section whose circumference is only partially surrounded by the compressor housing, and / or the

[0022] The second cooling channel can have a cooling channel cross-section whose circumference is only partially surrounded by the bearing disc.

[0023] In other words, the cooling channel cross-section is not completely limited by the compressor housing or either of the two bearing discs. For example, one side is limited by the second bearing disc or a flange plate.

[0024] This method advantageously allows for simpler manufacturing of the cooling channel, as it eliminates the need for slides in a casting tool for the compressor housing or the bearing disc. This has a positive impact on manufacturing costs.

[0025] According to a preferred embodiment, a radial compressor can further comprise a third cooling channel, which is arranged between the compressor housing and the bearing disk and is particularly annular in shape; wherein the third cooling channel has at least one inlet for the cooling air and at least one outlet for the cooling air; wherein the inlet is fluidically connected to the first cooling channel and the outlet is fluidically connected to the second cooling channel. The annular design of the third cooling channel enables a uniform distribution of the cooling air, which enters the third cooling channel through, for example, a single first cooling channel and exits the third cooling channel into two second cooling channels. For example, a plurality of second cooling channels can be distributed around the circumference of the third cooling channel. This allows for optimal cooling of the axial foil bearing.The third cooling channel can preferably be bounded by the compressor housing, the first bearing disk, and the second bearing disk. Alternatively, the third cooling channel can be bounded by the compressor housing, the first bearing disk, the second bearing disk, and a flange plate. This allows the third cooling channel to be manufactured in the simplest possible way. This has a positive effect on manufacturing costs and simultaneously on the efficiency of the radial compressor. The inlet of the third cooling channel corresponds to the first cooling channel, or the outlet of the first cooling channel. The outlet of the third cooling channel corresponds to the inlet of a second cooling channel, or to a second cooling channel.

[0026] Furthermore, according to a preferred further development, the third cooling channel of a radial compressor can have a plurality of outlets, wherein the plurality of outlets is distributed over a circumference of the third cooling channel.

[0027] The large number of outlets of the third cooling channel indicates a large number of second cooling channels.

[0028] This allows for improved cooling air supply, which has a positive effect on the efficiency of the radial compressor.

[0029] In a preferred embodiment of a radial compressor, the dimensions of the outlets can be identical to achieve uniform cooling, or the dimensions of the outlets can differ to achieve targeted airflow in a specific area. The dimensions preferably refer to the width and height of the outlet cross-sections. The dimensions preferably refer to the dimensions of the secondary cooling channels.

[0030] In this way, the cooling of the axial foil bearing can be advantageously optimized overall, according to the cooling requirements.

[0031] Furthermore, according to a preferred further development, in a radial compressor, at least one inlet and at least one outlet can be arranged offset from each other.

[0032] The inlet refers to the first cooling channel.

[0033] The staggered arrangement allows for a uniform flow through the third cooling channel.

[0034] In this way, the cooling of the axial foil bearing can be advantageously optimized.

[0035] In a preferred further development, in a radial compressor, a first boundary surface of the third cooling channel can be formed by the bearing disk and a second boundary surface of the third cooling channel can be formed by the compressor housing, with the first boundary surface and the second boundary surface being opposite each other.

[0036] In other words, the compressor housing and the bearing disk are designed and arranged in such a way that a third cooling channel is formed between them. This third cooling channel can be at least partially annular.

[0037] This has a positive effect on manufacturing costs, as it eliminates the need for complex casting tools with slides or extensive machining. A further aspect of the present disclosure relates to a method for manufacturing a compressor housing and / or a bearing disk for a radial compressor, as described above, wherein the first cooling channel and the second cooling channel are produced by primary forming.

[0038] The bearing disk and / or the compressor housing can be manufactured by primary forming, for example, aluminum casting. The first and second cooling channels can be formed by cores or slides with complete encirclement. Alternatively, the first and second cooling channels can also be advantageously manufactured without cores or slides with partial encirclement. The third cooling channel results from the arrangement of the bearing disk and the compressor housing relative to each other.

[0039] Another aspect of the present disclosure relates to a method for manufacturing a compressor housing and / or a bearing disk for a radial compressor described above, wherein the first cooling channel and the second cooling channel are manufactured by machining or ECM processes.

[0040] The bearing disc and / or the compressor housing can, for example, be provided as a semi-finished product in a preliminary step using a primary forming process.

[0041] Another aspect concerns a fuel cell system comprising at least one fuel cell with a radial compressor as described above.

[0042] Another aspect concerns the use of a bearing disc and / or a compressor housing in a radial compressor described in more detail and / or in a fuel cell system described in more detail above.

[0043] Advantages described in detail with respect to the radial compressor for a fuel cell system according to the first aspect of the invention apply equally to the method for manufacturing a compressor housing and / or a bearing disk for a radial compressor described in more detail above, to the fuel cell system, and to the use of a bearing disk and / or a compressor housing according to the further aspects of the invention.

[0044] A radial compressor according to the invention is explained below with reference to the drawings. The drawings schematically show:

[0045] Figure 1 shows a section view of a radial compressor.

[0046] Figure 2 shows a section view of a radial compressor and

[0047] Figure 3 shows a sectional view of a third cooling channel.

[0048] Figure 1 schematically shows a section of a radial compressor 10 in a sectional view along the longitudinal axis or axis of rotation 30. The radial compressor 10 serves to supply air to a fuel cell system for a vehicle. The radial compressor 10 comprises a compressor shaft 12. The compressor shaft 12 is driven by an electric motor. The electric motor includes a rotor 20, which is arranged on the compressor shaft 12. The electric motor also includes a stator 21. The electric motor is arranged in a compressor housing 11 of the radial compressor 10. A compressor wheel 13 is arranged on the compressor shaft 12. The compressor wheel 13 draws in ambient air and compresses it. The compressed ambient air is then supplied to a cathode of the fuel cell system. The compressor shaft 12 is supported in the compressor housing 11 by a bearing arrangement 14 comprising an axial foil bearing 15 and a radial bearing 19.The axial foil bearing 15 comprises a first bearing disk 16 on which a first foil is arranged. The bearing disk 16 is rigidly connected to a flange plate 23. The flange plate 23 is rigidly connected to the compressor housing 11. The axial foil bearing 15 comprises a second bearing disk 17 on which a second foil is arranged. The second bearing disk 17 is rigidly connected to the compressor housing 11. The axial foil bearing 15 comprises a rotating disk 18, which is rigidly connected to the compressor shaft 12.During operation, an air film forms between the rotating disk 18 and the first film, as well as between the rotating disk 18 and the second film, which carries the axial load. A first cooling channel 25 is integrally arranged in the compressor housing 11. For this purpose, the compressor housing 11 has a circumferential web 32, which in this case is in contact with the first bearing disk 16. The first cooling channel 25 is arranged in this circumferential web 32. Alternatively, the circumferential web 32 could also be arranged at the level of the bearing flange, so that the circumferential web 32 would be in contact with the flange plate 23. The first cooling channel 25 serves to supply cooling air to the axial film bearing 15. The cooling channel 25 is completely enclosed by the compressor housing 11. The cooling channel 25 is supplied with cooling air or compressed air.The cooling air can, for example, be diverted from a stream of compressed ambient air and fed to an inlet 26 of the first cooling channel 25. The air can be fed to the inlet 26, for example, via an outer wall of the compressor housing. The cooling air can also be cooled by water cooling (not shown) on its way to the inlet 26. The cooling air flows through an outlet 27 of the cooling channel 25 to a second cooling channel 28. The second cooling channel 28 is integrally arranged in the second bearing disk 17. The second bearing disk 17 has a circumferential web 33 for this purpose. In an installed state, the second bearing disk 17 is in contact with the first bearing disk 16. The second cooling channel 28 is completely enclosed within the web 33. The first cooling channel 25 and the second cooling channel 28 are fluidically in contact.The second cooling channel 28 has an inlet 29 and an outlet 31. In this case, there is a free space or cavity between the cooling channels 25 and 28. Alternatively, the cooling channels could be in direct contact. The cooling air exits the outlet 31 of the second cooling channel 28 to cool the axial foil bearing 15. After passing the axial foil bearing 15, the cooling air can exit the compressor housing 11 through a gap 34. It should be noted that several cooling channels can be arranged around the circumference of the axial foil bearing 15.

[0049] Fig. 2 shows a sectional view of a section of a radial compressor 50. In contrast to the radial compressor 10 in Fig. 1, the first cooling channel 53 is not completely enclosed by the compressor housing 51 or its circumferential web. The cross-section of the first cooling channel 53 is only bounded on three sides by the compressor housing 51. The fourth side is bounded by the first bearing disk 55. Furthermore, the second cooling channel 54 is not completely enclosed by the second bearing disk 52 or its circumferential web. The fourth side is bounded by the first bearing disk 55.

[0050] Fig. 3 shows a sectional view perpendicular to the axis of rotation of the radial compressor, revealing a third cooling channel 100. The third cooling channel 100 is bounded by the compressor housing 105 and the second bearing disk 108. The third cooling channel is annular in shape. In this case, the third cooling channel 100 extends over 180° of the circumference 107. Optionally, the

[0051] The third cooling channel 100 also extends over the entire circumference 107, i.e., over 360°. The first cooling channel of the compressor housing 105 serves as the inlet 102 for the third cooling channel 100. The second bearing disk 108 has two secondary cooling channels 103 and 104, which function as

[0052] Outlets 104 and 108 serve the third cooling channel 100. Outlets 104 and 108 are offset from inlet 102, allowing the cooling airflow 106 to distribute itself around the circumference 107 and cool the axial foil bearing as effectively as possible.

Claims

Claims 1. Radial compressor (10, 50) for a fuel cell system, comprising a compressor housing (11, 51, 105), a compressor shaft (12) and a bearing arrangement comprising an axial foil bearing (15), wherein the compressor shaft (12) is axially supported in the compressor housing (11 , 51 , 105) via the axial foil bearing (15), characterized by that the compressor housing (11 , 51 , 105) includes at least one integrally formed first cooling channel (25, 53, 102), wherein the axial foil bearing (15) is a bearing disk (17, 52, 108) with at least one integrally formed second cooling channel (28, 54, 103, 104) for supplying cooling air to the axial foil bearing (15), wherein the first cooling channel (25, 53, 102) is in fluidic contact with the second cooling channel (28, 54, 103, 104), so that cooling air flows from the first cooling channel (25, 53, 102) to the second cooling channel (28, 54, 103, 104).

2. Radial compressor (10, 50) according to claim 1 , characterized by that the first cooling channel (25, 53, 102) has a cooling channel cross-section whose circumference is completely separated from the Compressor housing (11, 51, 105) is surrounded and / or that the second cooling channel (28, 54, 103, 104) has a cooling channel cross-section whose circumference is completely surrounded by the bearing disk (17, 52, 108).

3. Radial compressor (10, 50) according to claim 1 , characterized by that the first cooling channel (25, 53, 102) has a cooling channel cross-section whose circumference is partially surrounded by the compressor housing (11, 51, 105) and / or that the second cooling channel (28, 54, 103, 104) has a cooling channel cross-section whose circumference is partially surrounded by the bearing disc (17, 52, 108).

4. Radial compressor (10, 50) according to one of the preceding claims, further comprising a third cooling channel (100) which is arranged between the compressor housing (11, 51, 105) and the bearing disk (17, 52, 108) and is in particular annular in shape, wherein the third cooling channel (100) has at least one inlet (102) for the cooling air and at least one outlet (103, 104) for the cooling air, wherein the inlet is fluidly connected to the first cooling channel (25, 53, 102) and the outlet is fluidly connected to the second cooling channel (28, 54, 103, 104).

5. Radial compressor (10, 50) according to claim 4, characterized by that the third cooling channel (100) has a plurality of outlets (103, 104), wherein the plurality of outlets (103, 104) is distributed over a circumference (107) of the third cooling channel (100).

6. Radial compressor (10, 50) according to claim 5, characterized by that the dimensions of the outlets (103, 104) are identical in order to achieve uniform cooling or that the dimensions of the outlets (103, 104) differ in order to achieve a targeted air supply in a specific area.

7. Radial compressor (10, 50) according to one of claims 4 to 6, characterized by that the at least one inlet (102) and the at least one outlet (103, 104) are arranged offset from each other.

8. Radial compressor (10, 50) according to one of claims 4 to 7, characterized by that a first boundary surface of the third cooling channel (100) is formed by the bearing disk (108) and a second boundary surface of the third cooling channel is formed by the compressor housing (105), wherein the first boundary surface and the second boundary surface opposite.

9. Method for manufacturing a compressor housing (11, 51, 105) and / or a bearing disk (17, 52, 108) for a radial compressor (10, 50) according to one of the preceding claims, characterized by that the first cooling channel (25, 53, 102) and the The second cooling channel (28, 54, 103, 104) is produced by primary forming.

10. Method for manufacturing a compressor housing (11, 51, 105) and / or a bearing disk (17, 52, 108) for a radial compressor (10, 50) according to any one of the preceding claims 1 to 8, characterized by that the first cooling channel (25, 53, 102) and the second cooling channel (28, 54, 103, 104) are manufactured by machining or ECM processes.

11. Fuel cell system comprising at least one fuel cell with a radial compressor (10, 50) according to any one of claims 1 to 8.

12. Use of a bearing disk (17, 52, 108) and / or a compressor housing (11, 51, 105) in a radial compressor (10, 50) according to any one of claims 1 to 8 and / or a fuel cell system according to claim 11.

Images