WO2019020288A1

WO2019020288A1 - Turbomachine, in particular for a fuel cell system

Info

Publication number: WO2019020288A1
Application number: PCT/EP2018/066415
Authority: WO
Inventors: Felix WIEDMANN
Original assignee: Robert Bosch Gmbh
Priority date: 2017-07-26
Filing date: 2018-06-20
Publication date: 2019-01-31
Also published as: DE102017212819A1

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 arranged on the shaft (14). A running surface (31) for axial mounting is formed on the axial bearing disk (30). The running surface (31) forms together with a corresponding bearing surface (81), an axial bearing (35). The axial bearing disk (30) comprises a first cover disk (34) and a second cover disk (35) that is arranged over said latter. Both cover disks (34, 35) are joined together by multiple ribs (36). The running surface (31) is formed on the first cover disk (34).

Description

Description title

Turbomachine, in particular for a Brennstoffzellensvstem 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 is an axial

Flowing and a radial flow end comprises.

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 object of the present invention is the optimization of such thrust washers.

Disclosure of the invention

The turbomachine according to the invention has a strength and weight-optimized thrust washer. 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. The thrust washer has a first cover plate and a second cover disc opposite thereto. The two cover plates are connected by a plurality of ribs. The tread is formed on the first cover plate. Preferably, the

Normal direction of the tread identical to the axis of the shaft.

The two cover plates are made comparatively thin, preferably with a maximum thickness of 2 mm. Therefore, the weight is the whole

Reduces axial bearing, and thus the rotation of the shaft

centrifugally induced stresses, which reduces the load on the thrust washer. The ribs, preferably a number of at least 20 ribs, give the thrust washer the necessary strength and rigidity, so that the deformation of the tread - and thus also potential wear - is minimized. For storage, the running surface cooperates with the bearing surface, which is formed, for example, stationary on a housing of the turbomachine or on a component connected to the housing.

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. As a result, the turbomachine has a very high efficiency. Functionally occur on the impeller but then fluidly resulting axial forces, which are supported by the thrust washer. An optimized

Axiallagerscheibe is therefore very effective especially for radial runners.

In particular, the stiffness of the tread is very important to unwanted

To avoid warping and thereby reduce wear on the tread and storage space can. Advantageously, the impeller is designed as a compressor, wherein the axial

Flow end of the flow inlet and the radial flow end of the

Represent flow output of the flow path. The compressor preferably has an electromagnetic drive device. By minimizing the weight of the thrust bearing disc, therefore, the required power of the drive device is reduced. 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, measures for reducing the axial force can then be made in the region of the rear side and the axial bearing disk, for example, a pressure divider can be arranged; This reduces the fluidic axial force acting on the shaft.

In advantageous embodiments, the ribs are designed to extend radially outward. As a result, the axial bearing disc is comparatively easy to manufacture, for example, as a castable executable. Nevertheless, weight and stiffness are approximate

designed rotationally symmetric, so that the concentricity of the thrust bearing is optimized. Preferably, the two cover plates are designed to be rotationally symmetrical. In advantageous developments, the axial bearing disk has on its inner periphery a hub with an inner bore formed therein. Preferably, the

Axial bearing washer pressed against the inner bore on the shaft. The hub is therefore provided with the smallest possible diameter, but preferably has comparatively much material for increasing the strength. However, since this material is only exposed to a relatively low peripheral speed, the corresponding centrifugal forces are minimized.

In advantageous developments, a further running surface is formed on the second cover disk. The other tread is opposite to the tread. Consequently, the further running surface of the bearing of the thrust washer serves in the

opposite direction to the tread of the first cover plate. The thrust bearing is thus acting in both directions. The bearing forces can be reduced in amount, since not necessarily a single axial effective direction of the force must be maintained, but a sign change is allowed.

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 passage for supplying an oxidant into the fuel cell, and an exhaust passage for discharging the oxidant from the fuel cell. The compressor is arranged in the air supply line. The air supply line is used In this case, the inflow of the working fluid or oxidant in the fuel cell, and the exhaust pipe is used for removal of 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. The minimized weight of the thrust washer contributes to increasing the efficiency of the entire turbo compressor. Furthermore, this increases the maximum possible acceleration of the impeller and thus the functionality of the turbocompressor. 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 turbocompressor is reduced. 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 shows schematically a fuel cell system with a turbocharger compressor

2 shows schematically a section through a turbomachine according to the invention, wherein only the essential areas are shown. FIG. 3 is a perspective view of an axial bearing disk of a turbomachine.

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 electrically driven by a drive device 20. 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.

2 schematically shows 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 on the shaft 14 arranged further impeller 13 includes a. 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. For this purpose, the impeller 15 has on its front side 15a a flow path 16, which comprises an axial flow end 18 and a radial flow end 17. 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 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 81 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 81 may be formed on a further connected to the housing 8 component.

In the embodiment of Figure 2, the thrust bearing 35 acts in both directions. Therefore, a further running surface 32 is formed on the axial bearing disk 30, opposite and opposite to the running surface 31, which has a further bearing surface 82

interacts. The further bearing surface 82 is formed on the housing 8, but may alternatively also be formed on a further component connected to the housing 8.

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 now the thrust washer 30 weight and strength optimized. FIG. 3 shows a perspective view of the axial bearing disk 30 of the turbomachine 10. The axial bearing disk 30 comprises two cover disks: a first cover disk 34 and a second cover disk 35. The two cover disks 34, 35 are arranged opposite one another and by a multiplicity of radial ribs 36 connected with each other. On its inner circumference, the thrust washer 30 has a hub 37 with an inner bore 38 formed therein. At the inner bore 38 is the

Thrust washer 30 arranged on the shaft 14, for example, pressed onto this.

The hub 37 and the two shrouds 34, 35 are preferably

formed rotationally symmetrical. The ribs 36 extend radially outward, so are arranged in a star shape. On the outer end face of the first cover plate 34 is the Tread 31 is formed. And in advantageous developments, the further running surface 32 is formed on the outer end face of the second cover disk 35, so that the axial bearing disk 30 is suitable for supporting both axial directions. The ribs 36, which advantageously have a number of at least 20, give the thrust washer 30 a very high strength with minimum weight. The use of only a single cover plate would have insufficient rigidity for the two treads 31, 32; only with a very thick - and thus very heavy - cover disc this would be possible. However, the use of the two relatively thin cover plates 34, 35 reduces the mass of the thrust washer 30 and thus the centrifugally induced stresses in the hub 37 significantly, which in particular reduces the stress on the hub 37 and thus increases the life of the thrust washer 30.

Claims

claims

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). wherein a running surface (31) for axial bearing is formed on the axial bearing disk (30), wherein the running surface (31) forms a thrust bearing (35) with a corresponding bearing surface (81),

characterized in that

the axial bearing disk (30) has a first cover disk (34) and a second cover disk (35) opposite thereto, wherein the two cover disks (34, 35) are interconnected by a plurality of ribs (36), wherein the running surface (31) adjoins the first cover plate (34) is formed.

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).

Turbomachine (10) according to claim 2

characterized in that the impeller (15) as a compressor (1 1) is carried out, wherein the axial flow end (18) represent the flow input and the radial flow end (17) the flow output of the flow path (16).

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).

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

characterized in that

the number of ribs (36) is at least 20.

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

characterized in that

the ribs (36) are designed to extend radially outward. 7. Turbomachine (10) according to one of claims 1 to 6

characterized in that

the two cover plates (34, 35) are rotationally symmetrical.

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

characterized in that

the axial bearing disk (30) has on its inner circumference a hub (37) with an inner bore (38) formed therein.

9. turbomachine (10) according to claim 8

characterized in that

the thrust washer (30) on the inner bore (38) is pressed onto the shaft (14).

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

characterized in that

a further running surface (32) is formed on the second cover disk (35), wherein the further running surface (32) is opposite to the running surface (31).

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

characterized in that

the two cover disks (34, 35) each have a maximum thickness of 2 mm.

12. A fuel cell system (1) having a fuel cell (2), an air supply line (3) for supplying an oxidizing agent in the fuel cell (2) and an exhaust pipe (4) for discharging the oxidizing agent from the fuel cell (2), characterized in that the Fuel cell system (1) a turbomachine (10) according to one of claims 1 to 1 1, wherein the impeller (15) is designed as a compressor (1 1) and wherein the compressor (1 1) in the

Air supply line (3) is arranged.

13. Fuel cell system (1) according to claim 12, 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.