WO2019020289A1

WO2019020289A1 - Turbomachine, in particular for a fuel cell system

Info

Publication number: WO2019020289A1
Application number: PCT/EP2018/066419
Authority: WO
Inventors: Andreas Wengert; Tobias Reinhard OTT
Original assignee: Robert Bosch Gmbh
Priority date: 2017-07-26
Filing date: 2018-06-20
Publication date: 2019-01-31
Also published as: DE102017212815A1

Abstract

The invention relates to a turbomachine (10), in particular for a fuel cell system (1). The turbomachine (10) comprises a shaft (14), an impeller wheel (15) and an axial bearing disk (30). The impeller wheel (15) and the axial bearing disk (30) are mounted on the shaft (14). A running surface (31) for axial mounting is formed on the axial bearing disk (30). The running surface (31) forms an axial bearing (35) with a corresponding bearing surface (86) A flow device (50) is arranged on the axial bearing disk (30). The flow device (50) is in a coolant fluid path (60).

Description

Description title

Turbomachinery, in particular for a fuel cell system. PRIOR ART Turbomachines designed as turbocompressors for a fuel cell system are known from the prior art, for example from the published patent application DE 10 2012 224 052 A1. The known turbocompressor has one of a

Drive device driven shaft on. On the shaft, a compressor and an exhaust gas turbine are arranged.

In a more detailed embodiment, a turbomachine designed as a turbocompressor is known from the published patent application DE 10 2008 044 876 A1. The known

Turbocompressor has an impeller arranged on a shaft. The impeller is designed as a radial runner, so is flowed through on its front by a working fluid along a flow path, wherein the flow path comprises an axial flow end and a radial flow end.

Furthermore, it is known from EP 2 006 497 A1 that the shaft of turbomachinery can be axially supported by means of an axial bearing disk.

The subject matter of the present invention is the configuration of the axial bearing washer in such a way that the cooling of the turbomachine is optimized.

Disclosure of the invention

The turbomachine according to the invention has an optimized thrust bearing, the cooling of the turbomachine, for example, the bearings and / or the

Drive device, serves. Preferably, the turbomachine is in one

Fuel cell system arranged. For this purpose, the turbomachine comprises a shaft, an impeller and the thrust washer. The impeller and the thrust washer are arranged on the shaft. At the

Axiallagerscheibe is designed a tread for axial storage. The tread forms a thrust bearing with a corresponding bearing surface. Preferably, the normal direction of the tread is identical to the axis of the shaft. At the axial bearing disc, a flow device is arranged. The flow device is located in a cooling fluid path.

As a result of the flow device, the axial bearing disk thus has a further function, namely a cooling function. The rotating flow device generates a flow, which is advantageously designed so that the cooling fluid path takes into account all critical tribo points of the turbomachine. The cooling fluid path serves to cool the turbomachine. A cooling fluid is purged by the flow device through the cooling fluid path and thereby carries the heat from the components of

Turbomachine off. Friction heat, which is to be cooled by the cooling fluid path or by the cooling fluid, is generated in particular at the tribological sites, such as bearings or drive devices. Preferably, the same medium can be used as cooling fluid, which flows as working fluid through the impeller.

In particular, the ambient air can be used for this purpose.

In advantageous developments, the impeller is designed as a radial rotor. The impeller is flowed through on its front by a working fluid along a flow path. The flow path includes an axial flow end and a radial flow end. Functionally occur on the impeller fluidically resulting

Axial forces, which are stored by the thrust washer. A

Axiallagerscheibe is thus a particularly suitable especially for radial runners

Component for the thrust bearing. If the impeller is designed as a radial runner, the turbomachine has a very high efficiency. In particular, for use in an air supply line of a fuel cell system, such a radial runner is well suited.

In advantageous developments, the cooling fluid path and the radial open

Flow end into an outlet. The outlet is preferably formed in a housing of the turbomachine and constitutes a common outlet of the working fluid and the cooling fluid from the turbomachine. For this purpose, working fluid and cooling fluid may be, for example, the ambient air. To cool the turbomachine is not the compressed by the impeller and thus heated working fluid used, but the cooling fluid, which flows through a separate inlet in the cooling fluid path. Thus, the turbomachine preferably has a parallel connection of the flow path and the cooling fluid path, which unite in front of the fuel cell.

In alternative advantageous embodiments, the flow path and the cooling fluid path do not unite. As a result, the pressure level of the working fluid compressed at the radial flow end is not lowered by the cooling fluid; the cooling fluid need not be promoted against the pressure of the radial flow end.

In advantageous developments, the axial bearing disk faces the rear side of the rotor wheel. As a result, the thrust washer is space-saving within the

Turbomachine arranged. Furthermore, in the area of the back and the

Axiallagerscheibe measures are then taken to Axialkraftreduzierung, for example, a pressure divider are arranged; As a result, the fluidically resulting axial force acting on the shaft is reduced, and with it also the frictional heat generated in the axial bearing.

In advantageous embodiments, the running surface faces the rear side of the running wheel. The normal direction of the tread thus points to the back of the wheel.

Preferably, the flow device thereby generates a flow in the

Cooling fluid path, which leads in the direction of the impeller. The cooling fluid can be mixed there with the working fluid or separated from it from the turbomachine. Preferably, the flow device is opposite to one of the tread

Gengenseite the thrust washer arranged. This is particularly advantageous if the thrust bearing only needs to support one direction, so that the thrust washer must have only one tread. The back or the opposite side of

Axiallagerscheibe has accordingly space for a further function, namely that for cooling. Furthermore, this makes it possible to flow the cooling fluid path very efficiently in the direction of the impeller, namely in a U-shaped cross-section around the axial bearing disk.

In advantageous embodiments, the flow device comprises a plurality of blades. Preferably, the flow device comprises three to six blades. The blades can be made straight, but also curved. The blades are preferred curved concavely in the direction of rotation, so that a very advantageous flow is generated radially outward. The cooling fluid path thus passes radially around the thrust washer, when viewed in section in a U-shape. In advantageous developments, the impeller is designed as a compressor, wherein the axial flow end represents the flow input and the radial flow end represents the flow output of the flow path. The compressor points

Preferably, an electromagnetic drive device. In particular, when used in a fuel cell system, this is a very efficient embodiment of a turbomachine.

Advantageously, the drive device is located in the cooling fluid path, preferably upstream of the flow device. In particular, in an electromagnetic drive device, not only the frictional heat is removed from the drive device, but also increases the efficiency of the drive device, which improves the efficiency of the entire turbomachine. For this purpose, not the entire drive device must be arranged in the cooling fluid path, but the cooling fluid path must be designed so that it can dissipate the largest possible amount of heat through the cooling fluid from the drive device. For this purpose, the cooling fluid path may, for example, pass between a rotor and a stator of the drive device.

In preferred embodiments, the shaft is supported by means of at least one radial bearing. The radial bearing is located in the cooling fluid path, so that the radial bearing is effectively cooled or even lubricated. Wear and potential cavitation erosion in the radial bearing are thereby minimized or avoided. The shaft can also be supported radially by means of two radial bearings. Advantageously, then both radial bearings are arranged in the cooling fluid path. Again, not the entire radial bearing must be arranged in the cooling fluid path, but the cooling fluid path be designed so that the cooling fluid can dissipate the largest possible amount of heat from the radial bearing. For this purpose, the cooling fluid path may, for example, pass between a bearing sleeve of the radial bearing and the shaft.

In advantageous uses, the turbomachine is arranged in a fuel cell system. The turbomachine is designed as a turbo compressor or the impeller as a compressor. The fuel cell system includes a fuel cell, an air supply pipe for supplying an oxidant into the fuel cell, and an exhaust pipe for discharging the oxidizer from the fuel cell. The compressor is arranged in the air supply line. The air supply line serves to the inflow of the working fluid or oxidant in the fuel cell, and the exhaust pipe is used to remove the oxidant or the reacted

Oxidizing agent or a mixture thereof from the fuel cell. The

Turbocompressor is designed according to one of the embodiments described above. Preferably, the impeller is designed as a radial runner and cooling fluid path and flow path are connected in parallel and open into one another in a common outlet. As the oxidizing agent and the cooling fluid, the ambient air is preferably used. The cooling of as many components of the turbomachine increases their efficiency and service life.

In advantageous developments, the fuel cell system has an exhaust gas turbine with a further impeller. The further impeller is also arranged on the shaft. The exhaust gas turbine is arranged in the exhaust pipe. Preferably, the further impeller of the exhaust gas turbine is arranged opposite to the impeller of the turbocompressor, so that the respective effective resulting axial forces on the two wheels partially compensate each other. The reacted working fluid or oxidizing agent flowing out of the fuel cell can be used very effectively as a power source for the exhaust gas turbine; As a result, the required drive power of the

Drive device for the turbo compressor reduced. Advantageously, while the exhaust pipe is separated from the cooling fluid path, so that the cooling fluid path no

heated medium is supplied. The fuel cell system may preferably be adapted to a

Drive drive device of a motor vehicle.

Brief description of the drawings

Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures. Show it: 1 schematically shows a section through a turbomachine according to the invention, wherein only the essential areas are shown. schematically a section through a turbomachine according to the invention, wherein only the essential areas are shown. a plan view of a thrust washer, only the essential areas are shown.

Detailed description of the invention

1 shows a fuel cell system 1 known from DE 10 2012 224 052 A1. The fuel cell system 1 comprises a fuel cell 2, an air supply line 3, an exhaust pipe 4, a compressor 1 1, an exhaust gas turbine 13, a bypass valve 5 for pressure reduction and a feed line not shown in detail for fuel to the fuel cell 2. The bypass valve 5, for example, a control valve his. As a bypass valve 5, for example, a wastegate valve can be used.

The fuel cell 2 is a galvanic cell that converts chemical reaction energy of a fuel supplied via the not shown fuel supply line and an oxidizing agent into electric energy shown in FIG

Embodiment is intake air, which is supplied via the air supply line 3 of the fuel cell 2. The fuel may preferably be hydrogen or methane or methanol. Accordingly, the exhaust gas is water vapor or water vapor and carbon dioxide. The fuel cell 2 is set up, for example

Drive drive device of a motor vehicle. For example, the electrical energy generated by the fuel cell 2 drives an electric motor of the

Motor vehicle on.

The compressor 1 1 is arranged in the air supply line 3. The exhaust gas turbine 13 is arranged in the exhaust pipe 4. The compressor 1 1 and the exhaust gas turbine 13 are mechanically connected via a shaft 14. The shaft 14 is of a drive device 20 electrically driven. The exhaust gas turbine 13 serves to support the drive device 20 for driving the shaft 14 or the compressor 11. The compressor 1 1, the shaft 14 and the exhaust gas turbine 13 together form a turbomachine 10. FIG. 2 shows schematically a longitudinal section of a turbomachine 10, in particular for use in a fuel cell system 1. The turbomachine 10 is designed in this embodiment as a turbocompressor 10 and has an arranged on the shaft 14 impeller 15, which acts as a compressor 1 1 and compressor.

In addition, the turbomachine 10 optionally has the exhaust gas turbine 13, which comprises a further impeller 13a arranged on the shaft 14. Preferably, the further impeller 13 a and the impeller 15 are positioned on the opposite ends of the shaft 14.

Advantageously, the turbomachine 10 is arranged in the fuel cell system 1, so that the impeller 15 of the compressor 1 1 is arranged in the air supply line 3 and so that the further impeller 13a of the exhaust gas turbine 13 is arranged in the exhaust pipe 4.

The impeller 15 is executed in the embodiment of Figure 2 as a radial rotor, so in the case of use as turbo compressor or compressor 1 1 flows axially and flows radially. The impeller 15 has on its front side 15a to a flow path 16, which comprises an axial flow end 18 and a radial flow end 1. As is usual with a radial runner, the direction of a working fluid flowing through the impeller 15 changes by approximately 90 ° in the sectional view. In the case of execution as a turbo compressor, the impeller 15 at the axial flow end 18 of the

Working fluid flows axially, the working fluid then passes through the flow path 16 on the front side 15 a and is thereby compressed and then occurs at the radial

Flow end 17 radially out of the impeller 15. On its front side 15a, the impeller 15 is at the pressure of the working fluid

applied. This pressure is not constant, but rises from

Inner diameter to the outer diameter on; this applies to the use of

Turbomachine 10 both as a turbocompressor and as a turbine. When using the turbomachine 10 as a turbine, only the direction of the flow path 16 is reversed, namely from the radial flow end 17 to the axial flow end 18; however, the qualitative pressure ratios on the front side 15a are the same as those of the first embodiment Turbo Compressor. The rear side 15b of the impeller 15 is constantly acted upon by the high pressure of the radial flow end 17. This results in a resulting fluidic force on the impeller 15, which acts in FIG. 2 to the left. Through various measures, this axial force can be reduced. However, a thrust bearing 35 is still required. The thrust bearing 35 comprises an axial bearing washer 30 arranged on the shaft 14. The axial bearing washer 30 can be pressed onto the shaft 14, for example, or, as shown in FIG. 2, by means of a nut 49 with the impeller 15 interposed against a shoulder of the shaft 14 be tense. The thrust bearing 30 has a preferably hardened and ground running surface 31 for the thrust bearing 35, which cooperates with a bearing surface 86, which is formed in the embodiment of Figure 2 on a housing 8 of the turbomachine 10. The housing 8 can also be designed in several parts or the bearing surface 86 may be formed on another connected to the housing 8 component.

Preferably, the turbomachine 10 is designed so that the fluidically resulting axial force always acts in one direction, so undergoes no sign reversal.

Consequently, only one bearing surface 86 is required because in the

opposite direction no axial bearing is necessary.

The drive device 20 of the turbomachine 10 embodied as a turbocompressor is designed as an electric motor, arranged between the compressor 11 and the exhaust gas turbine 13 and comprises a rotor 21 and a stator 22. The rotor 21 is likewise arranged on the shaft 14. The stator 22 is stationarily positioned in the only partially illustrated housing 8 of the turbocompressor 10. The housing 8 can also be designed in several parts. The shaft 14 is rotatably mounted on both sides of the drive device 20 by means of a respective radial bearing 41, 42. The drive device 20 is positioned between the two radial bearings 41, 42. At the outer ends of the shaft 14, the impeller 15 is disposed at one end and the other impeller 13 a, which forms the exhaust gas turbine 13 at the other end.

According to the invention, the axial bearing disk 30 now has a flow device 50 on a counter side 32 facing away from the running surface 31. The

Flow device 50 is designed to suck cool, non-compressed working fluid from a region of turbomachine 10 remote from impeller 15 in such a way that that thereby the two radial bearings 41, 42 and the drive device 20 are cooled.

3 shows a section through a turbomachine 10 with a sketched cooling fluid path 60. The cooling fluid path 60 leads from an inlet 81 formed in the housing 8 via the two radial bearings 41, 42, the drive device 20 and the thrust washer 30 to one another The inlet 81 is formed adjacent to the compressor wheel 13 a, but preferably should not receive the working fluid flowing through it. The outlet 82 is formed at the other end of the shaft 14 adjacent to the radial flow end 17 of the impeller 15. There, the cooling fluid, which has flowed through the cooling fluid path 60, with the compressed by the impeller 15 working fluid, which flows out of the radial flow end 17, mix, or be performed separately from this from the turbomachine 10.

The flow device 50 preferably has a plurality of blades. FIG. 4 shows a plan view of the opposite side 32 of the axial bearing disk 30. Six curved blades 51 are arranged on the opposite side 32. Upon rotation of the shaft 14 - and with it the thrust washer 30 - is generated by the blades 51, an air flow or flow of the cooling fluid from radially inward to radially outward. Accordingly, the cooling fluid around the thrust washer 30 - seen in the section of Figure 3 as a U-shape - deflected, and thereby passes to the side of the tread 31 and the bearing surface 86, and from there to the outlet 82, where it in further developments of the invention can mix with the compressed by the impeller 15 working fluid.

The blades 51 in the embodiment of Figure 4 have a curved shape, but may alternatively have a straight shape.

The mode of operation of the turbomachine 10 according to the invention, in particular for use in a fuel cell system 1, is as follows:

In order to operate the fuel cell 2, on the one hand, the fuel and the oxidizing agent, preferably air from the environment, must be provided. On the driven by the drive device 20, rotating shaft 14, the impeller 15 is mounted, which promotes the required air mass flow through the air supply line 3 in the direction of the fuel cell 2. For storage of the shaft 14 are in the Turbomachine 10 bearings provided, namely preferably the two radial bearings 41, 42 and the thrust bearing 35. The resulting in the bearings 35, 41, 42 frictional heat must be dissipated by a suitable cooling. For this purpose, for example, air, which is passed through the turbomachine 10 is suitable.

In order to optimize this cooling air flow, according to the invention, the already heated, compressed air from the impeller 15 should not be used, but cooled, uncompressed air should be sucked in from the opposite direction, so that the cooling becomes more effective. For this purpose, the thrust washer 30 on the opposite side 32 blades 51. This makes it possible to suck in fresh air from the environment through the inlet 81 and to guide it through the turbomachine 10.

This results in the following advantages: Already heated air of the compressor 1 1 or impeller 15 need not be used for cooling the turbomachine 10.

- Decoupling the intended for the fuel cell 2 amount of air from the

Amount of cooling air.

- Improvement in the efficiency of the turbomachine 10.

Claims

Claims 1. Turbomachine (10), in particular for a fuel cell system (1), having a shaft (14), an impeller (15) and a thrust washer (30), the impeller (15) and the thrust washer (30) being mounted on the shaft (14). are arranged, wherein on the Axiallagerscheibe (30) has a running surface (31) is formed for axial mounting, wherein the running surface (31) with a corresponding bearing surface (86) a

Thrust bearing (35) forms,

characterized in that

a flow device (50) is arranged on the axial bearing disk (30), wherein the flow device (50) lies in a cooling fluid path (60).

2. Turbomachine (10) according to claim 1

characterized in that

the impeller (15) is designed as a radial runner, wherein the impeller (15) on its front side (15a) by a working fluid along a flow path (16) can be flowed through, wherein the flow path (16) has an axial flow end (18) and a radial flow end (17).

3. Turbomachine (10) according to claim 2

characterized in that

the cooling fluid path (60) and the radial flow end (17) open into an outlet (82).

4. Turbomachine (10) according to one of claims 1 to 3

characterized in that

the thrust washer (30) faces the rear side (15b) of the impeller (15).

5. turbomachine (10) according to claim 4

characterized in that

the running surface (31) faces the rear side (15b) of the impeller (15).

6. Turbomachine (10) according to one of claims 1 to 5

characterized in that the flow device (50) is arranged on a gene side (32) of the axial bearing disk (30) opposite the running surface (31).

7. Turbomachine (10) according to one of claims 1 to 6

characterized in that

the flow device (50) comprises a plurality of blades (51).

8. Turbomachine (10) according to one of claims 1 to 7

characterized in that the impeller (15) as a compressor (1 1) with a drive device (20) is executed, wherein the axial flow end (18) the

Flow input and the radial flow end (17) represent the flow output of the flow path (16).

9. turbomachine (10) according to claim 8

characterized in that

the drive device (20) lies in the cooling fluid path (60), preferably

upstream of the flow device (50).

10. Turbomachine (10) according to one of claims 1 to 9

characterized in that

the shaft (14) is supported by means of at least one radial bearing (41, 42) and that the radial bearing (41, 42) lies in the cooling fluid path (60).

1 1. Fuel cell system (1) with a fuel cell (2), an air supply line (3) for supplying an oxidizing agent in the fuel cell (2) and a

Exhaust line (4) for discharging the oxidizing agent from the fuel cell (2), characterized in that the fuel cell system (1) comprises a turbomachine (10) according to one of claims 1 to 10, wherein the impeller (15) as a compressor (1 1) is executed and wherein the compressor (1 1) in the

Air supply line (3) is arranged.

12. The fuel cell system (1) according to claim 11, wherein the fuel cell system (1) has an exhaust gas turbine (13) with a further impeller (13a), wherein the further impeller (13a) is arranged on the shaft (14), wherein the exhaust gas turbine (13) in the exhaust pipe (4) is arranged.