DE102018212569A1 - turbomachinery - Google Patents

Abstract

Turbo machine (100) with a turbo housing (56) and an impeller (1) which is movably mounted about an axis of rotation (30) and which defines on the front side an inflow region (8) and an outflow region (9) of a working medium. On the back, the impeller (1) interacts with the turbo housing (56) and thus forms an axial gap (5). Furthermore, the turbo housing (56) has a shoulder (10), which shoulder (10) forms a sealing gap (18) with the impeller (1), the width of the sealing gap (18) approximately corresponding to the width of the axial gap (5). In addition, the impeller (1) and the turbo housing (56) delimit a leakage space (14), which is divided into a first leakage partial space (140) and a second leakage partial space (141) by the sealing gap (18).

Description

The present invention relates to a turbomachine which can be used, for example, in a waste heat recovery system for waste heat recovery from an internal combustion engine or as a compressor for a fuel cell system.

State of the art

From the published application DE 10 2014 226 951 A1 is an example of a turbomachine for a waste heat recovery system of an internal combustion engine, which comprises a housing and an impeller arranged on a drive shaft. The turbomachine has an inflow area and an outflow area and a working medium flows through it during operation. The working medium flows into the inflow area, along a front side formed on the impeller and then out of the outflow area, with a pressure drop on the front side between the inflow area and the outflow area. At the same time, an axial force acts on the impeller, which leads to high stress on an axial bearing. To reduce the axial force, a pressure divider is therefore arranged on a rear side of the impeller opposite the front side. The pressure divider lowers the pressure, which acts on at least part of the rear, compared to the pressure level of the inflow area. In this way, a resulting hydraulic force acting on the impeller can be set. The pressure divider can be designed as a throttle, steam-lubricated seal, labyrinth seal or as a media-tight seal.

In the case of a pressure divider designed as a throttle, the impeller cooperates with the housing of the turbomachine to form a gap, in particular to form an axial gap. On the one hand, due to manufacturing and / or assembly tolerances, the axial gap can widen and the associated leakage can reduce the efficiency of the turbomachine. On the other hand, manufacturing and / or assembly tolerances can lead to a reduction in the axial gap or even to contact of the impeller with the housing part, so that the thrust bearing and the impeller are exposed to high wear.

The object of the present invention is to provide a turbomachine which reduces the leakage at the axial gap and minimizes the overall wear of the components in the turbomachine, such as wear on the impeller.

Disclosure of the invention

The turbomachine according to the invention with the characterizing features of claim 1 has the advantage that the leakage at the axial gap is reduced without the use of an additional component as a pressure divider and thus an increase in the efficiency of the turbomachine is achieved.

For this purpose, the turbomachine has a turbo housing and an impeller movably mounted about an axis of rotation, which defines an inflow region and an outflow region of a working medium on a front side and interacts with the turbo housing on a rear side and thus forms an axial gap. In addition, the turbo housing has a shoulder on the back, which forms a sealing gap with the impeller. The width of the sealing gap approximately corresponds to the width of the axial gap. Furthermore, the impeller and the turbo housing delimit a leakage space, which is divided by the sealing gap into a first leakage part space and a second leakage part space.

For example, a pressure divider, here by forming a shoulder with a leakage space on the turbo housing, can be implemented. Furthermore, the axial force on the impeller can be reduced in that the pressure on the back of the impeller is reduced by the shoulder in comparison to the front of the impeller in the inflow area. In this way, wear on the impeller can be reduced and the functionality of the turbomachine can be optimized.

In a first advantageous development it is provided that the sealing gap has a width of less than 0.05 mm. The width of the axial gap advantageously has a value between 0.005 mm and 0.03 mm. In this way, the leakage at the sealing gap and the axial gap can be kept low and a higher efficiency of the turbomachine can be achieved.

In a further embodiment of the invention, it is advantageously provided that the second leakage sub-space is connected to a channel, which channel guides leakage out of the turbomachine. Leakage can thus be led out of the turbomachine in a simple and space-saving manner.

In an advantageous development, it is provided that the impeller has a recess at the level of the axial gap, so that the resulting acting force on the impeller can be adjusted via the dimension of the recess.

In a further embodiment of the invention, it is advantageously provided that the turbo housing forms an axial bearing for the impeller and that Thrust bearing is designed as a gas bearing. In this way, an efficient functioning of the impeller and thus the turbomachine is achieved.

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 has a fuel cell, an air supply line for supplying a working medium in the form of an oxidizing agent to the fuel cell and an exhaust gas line for removing the oxidizing agent 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 for removing the oxidizing agent or the reacted oxidizing agent or a mixture thereof from the fuel cell. The turbo compressor is designed according to one of the embodiments described above.

The described designs of the turbomachine are preferably used in a waste heat recovery system. The waste heat recovery system has a circuit carrying a working medium, which comprises a fluid pump, an evaporator, a turbomachine unit and a condenser in the flow direction of the working medium. The turbomachine unit further comprises a generator and the turbomachine according to the invention. The efficiency of the waste heat recovery system can be increased by using the turbomachine according to the invention.

list of figures

• 1 shows schematically a waste heat recovery system, only the essential areas are shown.
• 2 shows a section of a turbomachine unit of the waste heat recovery system from the 1 in a perspective view, only the essential areas are shown.
• 3 shows a first embodiment of a turbomachine according to the invention of the turbomachine unit in area A from the 2 in longitudinal section, only the essential areas are shown.
• 4 shows a second embodiment of a turbomachine according to the invention of the turbomachine unit in area A from the 2 in longitudinal section, only the essential areas are shown.
• 5 shows schematically a known fuel cell system, only the essential areas are shown.

Description of the embodiments

1 shows schematically a waste heat recovery system 44 an internal combustion engine 40 , where only the essential areas are shown.

The waste heat recovery system 44 has a circuit carrying a working medium 32 on a fluid pump in the direction of flow of the working medium 33 , an evaporator 34 , a turbo machine 100 and a capacitor 35 includes. The condenser 35 can, for example, to a cooling system of an internal combustion engine 40 be coupled.

Parallel to the turbo machine 100 is a bypass line 36 connected. By means of a bypass valve 37 the mass flow of the working medium can be transferred to the turbomachine as required 100 and / or the bypass line 36 be divided.

The turbo machine 100 is part of a turbomachine unit here 1000 , The turbo machine unit 1000 additionally includes a generator 42 , optionally also the bypass valve 37 and the bypass line 36 , The generator 42 converts that into the turbo machine 100 generated mechanical energy in electrical energy and thus feeds consumers, not shown, or a storage medium.

The waste heat recovery system is optional 44 continue - as in 1 shown - a tank 41 have, by means of a metering valve 38 Working medium in the cycle 32 can be initiated, or in the excess working medium from the circuit 32 can be traced back. Alternatively, the tank 41 thereby also in the cycle 32 be arranged.

How the waste heat recovery system works

The fluid working medium is supplied by the fluid pump 33 under pressure to the evaporator 34 and on to the turbo machine 100 promoted. The evaporator 34 is to an exhaust pipe of the internal combustion engine 40 connected, so uses the thermal energy of the exhaust gas of the internal combustion engine 40 and thus evaporates the working medium of the circuit 32 , The gaseous working medium is then in the turbomachine 100 relaxed with the release of mechanical energy. In the condenser 35 the working medium is completely liquefied and thus reaches the fluid pump again 33 ,

Preferably, the turbomachine 100 and the generator 42 a common wave 12 on so in the generator 42 in a simple way using one on the shaft 12 arranged rotor 61 and a stator 59 electrical energy can be generated (see 2 ).

The bypass line 36 is parallel to the turbo machine 100 arranged. Depending on the operating conditions of the internal combustion engine 40 and the waste heat recovery system 44 and the resulting variables, for example temperatures of the working medium, become the working medium of the turbomachine 100 fed or through the bypass line 34 on the turbo machine 100 past.

2 shows a section of the turbomachine unit 1000 from the 1 in a perspective view, only the essential areas are shown. The turbo machine unit 1000 includes the turbo machine 100 and the generator 42 , The turbo machine 100 is designed as a radial turbine, the flow output here from the radial turbine from the generator 42 leads away.

The turbo machine unit 1000 has a housing 55 on. In the execution of the 2 is the housing 55 Made in several parts and includes a turbo housing 56 , a generator housing 57 and a stator plate 58 , The turbo housing 56 essentially surrounds the turbomachine 100 , The generator housing 57 surrounds the stator 59 , The stator plate 58 is between the turbo housing 56 and the generator housing 57 clamped and fixed together with the generator housing 57 the stator 59 inside the case 55 ,

A warehouse 60 to support the shaft 12 is radial through the generator housing 57 positioned and axially between the generator housing 57 and the stator plate 58 positioned, i.e. between the turbo machine 100 and the generator 42 arranged. Another camp 600 is on the other side of the generator 42 arranged.

The generator housing 57 is made in two parts, with an inner body 570 and an outer jacket 571 ,

The flow path of the working medium in the execution of the 2 is the following: from the evaporator 34 coming, the gaseous working medium flows radially into the turbomachine 100 in and axially out of this through an outflow area 9 again in the representation of the 2 to the right. This is in the turbo machine 100 an impeller 1 driven. Then the working medium after exiting the turbomachine 100 in the condenser 35 completely liquefied.

In advantageous designs, the impeller 1 the 2 arranged upside down so that the outflow towards the generator 42 he follows. The flow of the working medium from the turbomachine unit 1000 is then preferably carried out in the radial direction between the turbo housing 56 and generator housing 57 , The outflow area 9 can do this from the turbo housing 56 and / or the generator housing 57 be limited. The warehouse 60 is in these versions advantageously on the right edge of the turbomachine unit 1000 arranged.

In advantageous developments, the turbomachine unit has 1000 then insulation between the turbomachine 100 and the generator 42 on. This can be done, for example, by a material of the housing 55 done with low thermal conductivity, or by an additional coating of the housing 55 or by another component of the housing 55 , The insulation can also trap air within the housing 55 include. The insulation has the task of being relatively hot, due to the outflow area 9 from the turbo machine 100 outflowing working medium thermally from the generator 42 to separate, so the efficiency of the generator 42 is not reduced.

3 shows an enlarged view A of the turbomachine 100 from the 2 , It shows a first embodiment of the turbomachine according to the invention 100 in longitudinal section. The turbo machine 100 has the turbo housing 56 on.

The impeller 1 is in the turbo housing 56 about an axis of rotation 30 arranged rotatably and here in one piece with the shaft 12 trained, the shaft 12 the turbo housing 56 interspersed. The illustration is shown in simplified form and on the longitudinal section above the axis of rotation 30 limited and can be used to complete the longitudinal section about the axis of rotation 30 be mirrored.

The impeller 1 has a front 20 and a back 21 on. The front 20 is arched and defines an inflow area 8th and the outflow area 9 for the working medium, in the representation of 3 from above and to the left. The backside 21 is flat and with one step 28 executed. Furthermore form the back 21 of the impeller 1 and the turbo housing 56 an axial gap 5 from which is a thrust bearing 27 for the impeller 1 forms. The axial gap 5 has a width between 0.005 mm and 0.03 mm.

Furthermore limit the back 21 of the impeller 1 and the turbo housing 56 a leakage room 14 , which is indicated by a paragraph 10 into a first leakage compartment 140 and a second leakage compartment 141 is divided. The second leakage compartment 141 is with one in the turbo housing 56 trained channel 16 connected, via which in the leakage room 14 collected leakage from the turbomachine 100 towards the capacitor 35 can be directed.

Paragraph 10 is here as a peripheral ridge on the housing part 2 trained and forms with the back 21 of the impeller 1 a sealing gap 11 out. The sealing gap 11 has a width of less than 0.05 mm. The width of the sealing gap 11 corresponds approximately to the width of the axial gap 5 , which results in low leakage and the functioning of the turbomachine 100 and thus improves their efficiency.

The working medium flow path is as follows: From the evaporator 34 coming, the gaseous working medium flows into the inflow area 8th the turbo machine 100 , On one edge 18 of the turbo housing 2 in the inflow area 8th between the impeller 1 and the turbo housing 2 the gaseous working medium is divided into two flow paths, one leading flow path at the front 20 and the other flow path at the back 21 of the impeller 1 past.

On the front side 20 the gaseous working medium flows in an arc along the impeller 1 towards the outflow area 9 and is powered by the impeller 1 or the wave 12 relaxed. Then the gaseous working medium from the turbomachine 100 towards the capacitor 35 passed and completely liquefied there.

At the back 21 the gaseous working medium flows into the first leakage subspace 140 and reaches the heel with high pressure 10 , Through the sealing gap 11 the working medium is relaxed and flows into the second leakage sub-area 141 on. There it flows into the axial gap 5 between the impeller 1 and the turbo housing 56 so the thrust bearing 27 is designed as a gas warehouse. On the other hand, the working medium flows over the channel 16 out of the turbo machine 100 towards the capacitor 35 ,

3 still shows a pressure curve 230 of the working medium on the front 20 of the impeller 1 , This decreases continuously to a constant value, ie the gaseous working medium is removed from the inflow area 8th to the outflow area 9 depressurized. At the back 21 of the impeller 1 is a pressure curve 231 of the working medium until the paragraph is reached 10 constant and then suddenly drops to a constant value. The backside 21 of the impeller 1 is therefore relieved of pressure somewhat earlier than the front 20 of the impeller 1 so the impeller 1 is relieved of force. To fulfill the thrust bearing function and a contact between the impeller 1 and the turbo housing 56 prevent the turbo housing 56 at the axial gap 5 advantageously stepped (see reference numerals 26 ) or includes the turbo housing 56 another channel 25 what pressure in the axial gap 5 can be generated.

4 also shows an enlarged view A of the turbomachine 100 from the 2 , It shows a second exemplary embodiment of the turbomachine according to the invention 100 in longitudinal section, with the longitudinal section only above the axis of rotation for simplification 30 is shown and to complete the longitudinal section about the axis of rotation 30 can be mirrored. The structure and mode of operation of the second exemplary embodiment largely corresponds to the first exemplary embodiment from FIG 3 ,

Here are the impeller 1 and the wave 12 executed as individual components that are firmly connected. The backside 21 of the impeller 1 is largely flat, also has an arcuate area 7 on which by an edge 6 is brought back into a flat form. The arcuate area 7 closes downstream of the axial gap 27 and leads the gaseous working medium after passing through the axial gap 27 into a cavity 15 that of the wave 12 and the turbo housing 56 is limited. The cavity 15 is with the capacitor 35 connected.

Furthermore, the channel 16 , which in the second leakage compartment 141 flows out again with the condenser 35 connected. In an alternative embodiment, the channel 16 a connecting channel 160 on the the channel 16 with the cavity 15 connects and so the working medium from the second leakage sub-area 141 over the channel 16 and the connecting channel 160 towards the capacitor 35 is dissipated.

At the level of the axial gap 27 points the impeller 1 a recess 24 on. The working medium flows into the inflow area 8th the turbomachine over the edge 18 of the turbo housing 56 in the first leakage compartment 140 , the gaseous working medium on the paragraph 10 depressurized. After entering the second leakage compartment 141 the working medium continues to flow into the axial gap 5 , in which the pressure of the working medium at the level of the recess 24 increases again until the end of the axial extent of the recess 24 and then relax again. In the first exemplary embodiment, however, the pressure of the working medium remains in the entire axial gap 5 constant.

On the front side 20 of the impeller 1 is a pressure drop between the inflow region in both exemplary embodiments 8th and the outflow area 9 available. At the same time acts on the impeller 1 an axial force here by training the paragraph 10 on the turbo housing 56 is reduced. Depending on the width of the axial gap 5 and with it the width of the sealing gap 11 and through the recess 24 in the impeller 1 can the resulting force on the impeller 1 be adjusted according to the operation and the life of the impeller 1 increase.

In an alternative embodiment, the recess 24 in the wheel 1 also be executed in the first embodiment.

4 still shows a pressure curve 233 of the working medium on the front 20 of the impeller 1 , This decreases continuously to a constant value, ie the gaseous working medium is removed from the inflow area 8th to the outflow area 9 depressurized. At the back 21 of the impeller 1 is a pressure curve 232 of the working medium until the paragraph is reached 10 constant and then suddenly drops to a constant value. When the recess is reached 24 the pressure of the working medium rises again in the impeller, whereby after passing through the recess 24 the pressure returns to the constant value before it passes through the recess 24 reduced and then remains constant. So the resulting force on the impeller 1 can be varied.

The turbomachine according to the invention 100 can also, as in 5 shown as a compressor 51 in a fuel cell system 46 be trained.

5 shows one from the DE 10 2012 224 052 A1 known fuel cell system 46 , The fuel cell system 46 includes a fuel cell 47 , an air supply line 48 , an exhaust pipe 49 acting as a compressor 51 trained turbo machine 100 , an exhaust gas turbine 52 , a bypass valve 50 for lowering the pressure and a supply line, not shown, for fuel to the fuel cell 47 , The bypass valve 50 can be a control valve, for example. As a bypass valve 50 For example, a wastegate valve can be used.

The fuel cell 47 is a galvanic cell that converts chemical reaction energy of a fuel supplied via the fuel supply line, not shown, and an oxidizing agent into electrical energy, which in the embodiment shown here is intake air, via the air supply line 48 the fuel cell 47 is fed. The fuel may preferably be hydrogen or methane or methanol. Accordingly, water vapor or water vapor and carbon dioxide are generated as exhaust gas. The fuel cell 47 is set up, for example, to drive a drive device of a motor vehicle. For example, it drives through the fuel cell 47 generated electrical energy to an electric motor of the motor vehicle.

The compressor 51 is in the air supply line 48 arranged. The exhaust gas turbine 52 is in the exhaust pipe 49 arranged. The compressor 51 and the exhaust gas turbine 52 are about a wave 12 mechanically connected. The wave 12 is from a drive device 54 electrically driven. The exhaust gas turbine 52 serves to support the drive device 54 to drive the shaft 12 or the compressor 51 , The compressor 51 , the wave 12 and the exhaust gas turbine 52 together form a turbo compressor 1000 ,

In an alternative embodiment, the exhaust gas turbine 52 in the fuel cell system 46 also omitted and the compressor 51 is multistage.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102014226951 A1 [0002]
• DE 102012224052 A1 [0046]

Claims (8)

Turbo machine (100) with a turbo housing (56) and an impeller (1) movably mounted about an axis of rotation (30), which defines an inflow area (8) and an outflow area (9) of a working medium on a front side (20) and on a rear side (21) cooperates with the turbo housing (56) and thus forms an axial gap (5), characterized in that the turbo housing (56) has a shoulder (10) on the rear side (21), which shoulder (10) with the impeller ( 1) forms a sealing gap (18), the width of the sealing gap (18) approximately corresponding to the width of the axial gap (5) and that the impeller (1) and the turbo housing (56) delimit a leakage space (14) which is defined by the sealing gap (18) is divided into a first leakage compartment (140) and a second leakage compartment (141). Turbo machine (100) after Claim 1 , characterized in that the sealing gap (18) has a width of less than 0.05 mm. Turbo machine (100) after Claim 1 or 2 , characterized in that the width of the axial gap (5) has a value between 0.005 mm and 0.03 mm. Turbomachine (100) according to one of the preceding claims, characterized in that the second leakage partial space (141) is connected to a channel (16), which channel (16) directs leakage from the turbomachine (100). Turbo machine (100) according to one of the preceding claims, characterized in that at the height of the axial gap (5) the impeller (1) has a recess (24) so that the resulting force acting on the impeller (1) over the dimension of the recess (24) is adjustable. Turbo machine (100) according to any one of the preceding claims, characterized in that the turbo housing (56) forms an axial bearing (27) for the impeller (1) and the axial bearing (27) is designed as a gas bearing. Fuel cell system (46) with a fuel cell (47), an air supply line (48) for supplying a working medium in the form of an oxidizing agent into the fuel cell (47) and an exhaust gas line (49) for removing the oxidizing agent from the fuel cell (47), characterized in that that the fuel cell system (46) has a turbomachine (100) designed as a compressor (51) according to one of the preceding claims in the air supply line (48) and an exhaust gas turbine (52) is arranged in the exhaust line (49) and the turbomachine (100) and the exhaust gas turbine (52) form a turbomachine unit (1000). Waste heat recovery system (44) with a circuit (32) carrying a working medium, the circuit (32) comprising a fluid pump (33), an evaporator (34), a turbomachine unit (1000) and a condenser (35) in the direction of flow of the working medium, wherein the turbomachine unit (1000) comprises a generator (42), characterized in that the turbomachine unit (1000) is a turbomachine (100) according to one of the Claims 1 to 6 includes.

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