DE102017212815A1 - Turbomachine, in particular for a fuel cell system - Google Patents

Abstract

Turbomachine (10), in particular for a fuel cell system (1). The turbomachine (10) comprises a shaft (14), an impeller (15) and a thrust washer (30). The impeller (15) and the thrust washer (30) are arranged on the shaft (14). On the thrust washer (30) has a running surface (31) is formed for axial storage. The running surface (31) forms a thrust bearing (35) with a corresponding bearing surface (86). On the thrust washer (30), a flow device (50) is arranged. The flow device (50) lies in a cooling fluid path (60).

Description

State of the 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 turbo-compressor has a shaft drivable by a drive device. On the shaft, a compressor and an exhaust gas turbine are arranged.

In a more detailed embodiment is designed as a turbo compressor turbomachine from the published patent application DE 10 2008 044 876 A1 known. The known turbo-compressor 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, from the EP 2 006 497 A1 It is known that the shaft of turbomachinery can be axially supported by means of a thrust washer.

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 axial bearing disk which serves to cool the turbomachine, for example the bearing points and / or the drive device. Preferably, the turbomachine is arranged in a fuel cell system.

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. On the thrust washer a tread for axial storage is formed. 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 flushed by the flow device through the cooling fluid path, thereby dissipating the heat from the components of the turbomachine. 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 fluidly resulting axial forces, which are supported by the thrust washer. An axial bearing disk is therefore a well-suited component for the axial bearing, in particular in radial runners. 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 flow end open 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. For cooling the turbomachine, therefore, not the working fluid compressed by the impeller and thus heated, but the cooling fluid, which flows into the cooling fluid path through a separate inlet, is used. 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 axial bearing disc is arranged to save space within the turbomachine. Furthermore, in the area of the rear side and the thrust washer then measures for Axialkraftreduzierung are taken, 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. In this case, the flow device preferably 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 arranged on one of the running surface opposite gengen side of the thrust washer. 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 rear side or the opposite side of the axial bearing disk accordingly has 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. Preferably, the blades are concavely curved 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 preferably has 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 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 serves for the inflow of the working fluid or oxidizing agent into the fuel cell, and the exhaust gas line serves to remove the oxidizing agent 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 counter to the impeller of the turbocompressor, so that the respective effective resulting axial forces on the two wheels partially compensate. The effluent from the fuel cell Reacted working fluid or oxidant 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. Advantageously, the exhaust gas line is separated from the cooling fluid path, so that no heated medium is supplied to the cooling fluid path.

The fuel cell system may preferably be configured to drive a drive device of a motor vehicle.

list of figures

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.

• 1 schematisch ein Brennstoffzellensystem mit einer als Turbokompressor ausgeführten Turbomaschine aus dem Stand der Technik,
• 2 schematisch einen Schnitt durch eine erfindungsgemäße Turbomaschine, wobei nur die wesentlichen Bereiche dargestellt sind.
• 3 schematisch einen Schnitt durch eine erfindungsgemäße Turbomaschine, wobei nur die wesentlichen Bereiche dargestellt sind.
• 4 eine Draufsicht auf eine Axiallagerscheibe, wobei nur die wesentlichen Bereiche dargestellt sind.

Show it:

• 1 1 is a schematic view of a fuel cell system with a turbomachine of the prior art, designed as a turbo-compressor;
• 2 schematically a section through a turbomachine according to the invention, wherein only the essential areas are shown.
• 3 schematically a section through a turbomachine according to the invention, wherein only the essential areas are shown.
• 4 a plan view of a thrust washer, only the essential areas are shown.

Detailed description of the invention

1 shows one from the DE 10 2012 224 052 A1 known fuel cell system 1 , The fuel cell system 1 includes a fuel cell 2 , an air supply line 3 , an exhaust pipe 4 , a compressor 11 , an exhaust gas turbine 13 , a bypass valve 5 for lowering the pressure and a feed line not shown in detail for fuel to the fuel cell 2 , The bypass valve 5 For example, it can be a control flap. 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 fuel supply line, not shown, and an oxidant into electrical energy, which in the embodiment shown here is intake air via the air supply line 3 the fuel cell 2 is supplied. 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 configured, for example, to drive a drive device of a motor vehicle. For example, it drives through the fuel cell 2 generated electrical energy while an electric motor of the motor vehicle.

The compressor 11 is in the air supply line 3 arranged. The exhaust gas turbine 13 is in the exhaust pipe 4 arranged. The compressor 11 and the exhaust gas turbine 13 are about a wave 14 mechanically connected. The wave 14 is from a drive device 20 electrically driven. The exhaust gas turbine 13 serves to support the drive device 20 to power the shaft 14 or of the compressor 11 , The compressor 11 , the wave 14 and the exhaust gas turbine 13 Together they 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 turbo machine 10 is in this embodiment as turbo compressor 10 executed and has one on the shaft 14 arranged impeller 15 on which as a compressor 11 or compressor acts. In addition, the turbomachine points 10 optionally the exhaust gas turbine 13 on which one on the shaft 14 arranged further impeller 13a includes. Preferably, the other impeller are 13a and the impeller 15 on the opposite ends of the shaft 14 positioned.

Advantageously, the turbomachine 10 in the fuel cell system 1 arranged so that the impeller 15 of the compressor 11 in the air supply line 3 is arranged and so that the further impeller 13a the exhaust gas turbine 13 in the exhaust pipe 4 is arranged.

The impeller 15 is in the execution of 2 designed as a radial runner, so in the case of use as turbo compressor or compressor 11 flows axially and flows radially. The impeller 15 points to this on his front 15a a flow path 16 on which an axial flow end 18 and a radial flow end 17 includes. As is common with a radial runner, the direction of one through the impeller changes 15 flowing working fluid in the sectional view by about 90 °. In the case of execution as turbo compressor is the impeller 15 at the axial flow end 18 flows axially from the working fluid, the working fluid then passes through the flow path 16 on the front side 15a and is compressed and then occurs at the radial flow end 17 radially out of the impeller 15 out.

On his front 15a is the wheel 15 subjected to the pressure of the working fluid. This pressure is not constant, but rises from Inner diameter to the outer diameter on; This applies to the use of turbomachinery 10 both as turbo compressor and as turbine. When using the turbomachine 10 as a turbine, only the direction of the flow path is reversed 16 around, namely from the radial flow end 17 to the axial flow end 18 ; the qualitative pressure conditions on the front 15a However, they are the same as the turbocharger compressor. The backside 15b of the impeller 15 is constant with the high pressure of the radial flow end 17 applied. This results in a resulting fluidic force on the impeller 15 which in the 2 works to the left.

Through various measures, this axial force can be reduced. However, it is still a thrust bearing 35 required. The thrust bearing 35 includes one on the shaft 14 arranged thrust washer 30 , The thrust washer 30 can do this, for example, on the wave 14 be pressed on, or - as in 2 shown - by means of a nut 49 with the intermediate wheel 15 against a shoulder of the shaft 14 be tense. The thrust washer 30 has a preferably hardened and ground tread 31 for the thrust bearing 35 on that with a storage area 86 cooperates in the execution of the 2 on a housing 8th the turbo machine 10 is trained. The housing 8th can also be executed in several parts or the storage area 86 can be on another with the case 8th be formed connected component.

Preferably, the turbomachine is 10 designed so that the fluidic axial force always acts in one direction, so undergoes no sign reversal. As a result, there is only one storage area 86 required, since in the opposite direction no axial bearing is necessary.

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

According to the invention now has the thrust washer 30 on one of the tread 31 facing away from the other side 32 a flow device 50 on. The flow device 50 is designed to cool, non-compressed working fluid from one impeller 15 distant area of the turbomachine 10 sucked so that thereby the two radial bearings 41 . 42 and the drive device 20 be cooled.

In addition shows 3 schematically a section through a turbomachine 10 with a sketched cooling fluid path 60 , The cooling fluid path 60 leads from one in the housing 8th trained inlet 81 over the two radial bearings 41 . 42 , the drive device 20 and the thrust washer 30 to one also in the case 8th trained outlet 82 , The inlet 81 is adjacent to the compressor wheel 13a designed, but preferably does not absorb the working fluid flowing through there. The outlet 82 is at the other end of the wave 14 adjacent to the radial flow end 17 of the impeller 15 educated. There, the cooling fluid, which is the cooling fluid path 60 through which flows through the impeller 15 compressed working fluid, which from the radial flow end 17 flows out, mix, or separate from this from the turbomachine 10 be guided.

The flow device 50 preferably has a plurality of blades. In addition shows 4 a plan view of the opposite side 32 the thrust washer 30 , At the opposite side 32 are six curved blades 51 arranged. Upon rotation of the shaft 14 - and with it the thrust washer 30 - gets through the blades 51 generates an air flow or flow of the cooling fluid from radially inward to radially outward. Accordingly, the cooling fluid becomes around the thrust washer 30 - on average the 3 as a U-shape - turned around, and thus reaches the side of the tread 31 or the storage area 86 , and from there to the outlet 82 , Where it is in developments of the invention with the by the impeller 15 compressed working fluid can mix.

The shovels 51 in the execution of 4 have a curved shape, but may alternatively have a straight shape.

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

To the fuel cell 2 To operate, on the one hand, the fuel and the oxidizing agent, preferably air from the environment, must be provided. On the of the drive device 20 driven, rotating shaft 14 is the wheel 15 attached, the required air mass flow through the air supply line 3 in the direction of the fuel cell 2 promotes. For storage of the shaft 14 are in the turbo machine 10 Storage locations provided, namely preferably the two radial bearings 41 . 42 and the thrust bearing 35 , The ones in the camps 35 . 41 . 42 The resulting frictional heat must be dissipated by suitable cooling. For this purpose, for example, air is suitable, through the turbomachine 10 is directed.

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

• - Bereits aufgeheizte Luft des Verdichters 11 bzw. Laufrads 15 muss nicht zur Kühlung der Turbomaschine 10 verwendet werden.
• - Entkopplung der für die Brennstoffzelle 2 vorgesehenen Luftmenge von der Kühlluftmenge.
• - Wirkungsgradverbesserung der Turbomaschine 10.

This results in the following advantages:

• - Already heated air of the compressor 11 or impeller 15 does not need to cool the turbomachine 10 be used.
• - Decoupling of the fuel cell 2 provided amount of air from the amount of cooling air.
• - Improvement in the efficiency of the turbomachine 10 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012224052 A1 [0001, 0023]
• DE 102008044876 A1 [0002]
• EP 2006497 A1 [0003]

Claims (12)

Turbomachine (10), in particular for a fuel cell system (1), having a shaft (14), an impeller (15) and an axial bearing disk (30), the impeller (15) and the axial bearing disk (30) being mounted on the shaft (14). wherein a running surface (31) for axial mounting is formed on the axial bearing disk (30), wherein the running surface (31) with a corresponding bearing surface (86) forms a thrust bearing (35), characterized in that on the axial bearing disk (30 ), a flow device (50) is arranged, wherein the flow device (50) lies in a cooling fluid path (60). Turbomachine (10) after 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) after Claim 2 characterized in that the cooling fluid path (60) and the radial flow end (17) open into an outlet (82). Turbomachine (10) after one of Claims 1 to 3 characterized in that the thrust washer (30) faces the rear side (15b) of the impeller (15). Turbomachine (10) after Claim 4 characterized in that the running surface (31) faces the rear side (15b) of the running wheel (15). Turbomachine (10) after one of Claims 1 to 5 characterized in that the flow device (50) on one of the running surface (31) opposite Gengenseite (32) of the thrust washer (30) is arranged. Turbomachine (10) after one of Claims 1 to 6 characterized in that the flow device (50) comprises a plurality of blades (51). Turbomachine (10) after one of Claims 1 to 7 characterized in that the impeller (15) is designed as a compressor (11) with a drive device (20), 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) after Claim 8 characterized in that the drive device (20) lies in the cooling fluid path (60), preferably upstream of the flow device (50). Turbomachine (10) after one of Claims 1 to 9 characterized in that the shaft (14) by means of at least one radial bearing (41, 42) is mounted and that the radial bearing (41, 42) in the cooling fluid path (60). Fuel cell system (1) with a fuel cell (2), an air supply line (3) for supplying an oxidizing agent into the fuel cell (2) and an exhaust line (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 10 wherein the impeller (15) is designed as a compressor (11) and wherein the compressor (11) in the air supply line (3) is arranged. Fuel cell system (1) after Claim 11 wherein the fuel cell system (1) comprises 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.

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