EP1222400B1 - Method and device for the indirect cooling of a flow regime in radial slits formed between the rotors and stators of turbomachines - Google Patents

Description

Technical area

The invention relates to a method and a device for indirect cooling the flow formed in between rotors and stators of turbomachinery Radial gaps, according to the preamble of claim 1 and the preamble of claim 7, but in particular for the indirect cooling of the flow in the radial gap between the compressor wheel and the housing of a centrifugal compressor.

State of the art

For sealing rotating systems are non-contact in turbomachinery Gaskets, especially labyrinth seals widely used. In the fluid flowed through Separating gap between rotating and stationary parts occurs as a result of Forming flow boundary layers on a high friction loss. This leads to a heating of the fluid in the separating gap and thus also to the heating the components surrounding the separation gap. The high material temperatures have a reduction in the life of the corresponding components result.

A simply constructed centrifugal compressor without one formed in the separation gap Sealing geometry is known from DE 195 48 852 A1. Also, it ensures the result resulting from flow shear layers on the rear wall of the compressor wheel Frictional heat for heating the compressor wheel and thus for a reduction of its life.

From EP 0 518 027 B1 is an air cooling for radial compressor with a sealing geometry known on the back of the compressor wheel. This is between the individual sealing elements an additional annular space on the housing wall side of the Radial compressor formed. In this annulus, a cold gas is introduced, which is higher than the pressure prevailing at the outlet of the compressor wheel having. The supplied air acts as impingement cooling. She shares in the Sealing area and flows mainly radially inwards and outwards. This should also have a barrier effect against the flow through the Separating gap achieved with hot compressor air from the exit of the compressor wheel become. The air injected in this way, however, provides for a thrust increase and for additional friction losses in the flow boundary layers.

In addition to this direct cooling is from DE 196 52 754 A1 also an indirect Cooling the rear wall of the compressor wheel or flowing through the separation gap Medium known. This is on or in the back wall and with this the separating gap forming housing part with the lubricating oil system of the Turbocharger connected supply and distribution arranged. As a cooling medium used for bearing lubrication oil, including the lubricating oil circuit of Turbocharger is tapped. A disadvantage of this cooling is the relatively high oil requirement and the heat to be dissipated by the oil cooler. This leads to a increased volume of the radiator. In addition, there is an accident with Damage to the corresponding components an increased risk of deflagration.

With the US 4815184 is also a water cooling of the bearing housing of a turbocharger known. However, this cooling is used to eliminate the risk of coking of remaining after the shutdown of the turbocharger in the bearing housing Lubricating oil. In contrast to the solutions of the prior art described above Technology is thus the supply of the cooling medium not during continuous operation but rather when switching off the turbocharger required. Therefore, this can Type of cooling of the bearing housing no indication of indirect cooling of the Flow formed in between rotors and stators of turbomachinery To give radial gaps. Moreover, this solution is explicitly not concerned with the cooling of the partition.

From US 2,384,251 an indirect cooling of the diffuser is known in which a Cooling medium is pumped through a surrounding the diffuser annular space. Also This document is not concerned with the cooling of the curtain wall and gives no indication of indirect cooling of the flow in between rotors and stators of turbomachinery formed radial gaps.

Presentation of the invention

The invention seeks to avoid all these disadvantages. It's up to you underlying, with respect to its cooling effect improved cooling method the flow formed in between rotors and stators of turbomachinery To create radial gaps. In addition, a simple, inexpensive and robust device for implementing the method can be specified.

According to the invention, this is achieved by using a method according to The preamble of claim 1, water as a cooling fluid for the radial gap adjacent stator part is used.

The water used as a cooling medium has a slightly higher density than the known lubricating oils and about twice as large specific heat capacity. Since the dissipated via a cooling medium heat flow proportional The product of density and specific heat capacity is obtained when used of water a distinct advantage over oil cooling. At the same Mass flow and the same temperature of the water can thus from the through the radial gap flowing medium on the stator part to be cooled a greater amount of heat to be withdrawn. The cooling effect on the at the radial gap adjacent areas of the rotor is therefore also larger. In reverse is used to derive the same amount of heat to the lubricating oil a smaller mass flow of cooling water needed, whereby the supply and discharge device can be dimensioned correspondingly smaller for the cooling medium.

For this purpose, at least one inside the radial gap adjacent stator Recess formed or disposed on the stator at least one cavity. The recess or the cavity is both with a supply line and connected to a discharge line for the cooling fluid. About these lines is the cooling fluid introduced or discharged again. Depending on the rotor side Wall thickness, which should be kept as low as possible, can through the the radial gap immediately adjacent water flow in the interior of the stator an improved cooling effect can be achieved. But instead of the recess formed in the stator of the cavity described on the stator, so can with equally good cooling effect a simpler and more cost-effective production will be realized.

In one of an internal combustion engine, a charge air cooler and an exhaust gas turbocharger existing system will either fresh water from outside the Systems or advantageously used in the system existing water as cooling fluid. In the latter case, this can be found in a cooling water circuit of the intercooler cooling water used, which branched off upstream of the intercooler becomes. The stationary stator part is a housing part of a radial compressor, which is the radial gap to the rotor, i. to the rotating compressor wheel an exhaust gas turbocharger limited.

As a recess of the stator part, a tube cast in the latter is formed, whereby a simple and robust cooling device is created. Alternatively is arranged in the stator at least one groove, wherein in each groove at least one inserted as a recess serving pipe and shed. Far easier in the production of course is a stator with at least one corresponding, cast-in core, which is removed to form the recess.

An additional benefit is achieved by removing the cooling fluid prior to water cooling of the radial gap adjacent stator for indirect cooling of the Main flow of the working medium downstream of the diversion of the leakage flow receiving diffuser and the diffuser delimiting the bearing housing Diffuser plate is used. This can also be done in this downstream Effective cooling of the material of the turbomachine can be achieved. In addition, the heat flow from the diffuser to the radial gap is adjacent Stator part reduced.

Particularly advantageous, in addition to the water cooling, a second cooling fluid is used and introduced into the radial gap, preferably using air comes. Due to the double cooling of the radial gap, the temperature of the thermally heavily loaded rotor are further lowered. These are at the radial gap at least one feed channel and a discharge device for the second Cooling fluid arranged.

By the supply of the second cooling fluid partially or completely turned off is, the cooling effect in a simple manner during operation of the turbomachine expected conditions or the current temperature conditions be adjusted.

Short description of the drawing

In the drawing, several Ausführungsbeispiete the invention with reference to a shown connected to an internal combustion engine exhaust gas turbocharger.

Fig. 1

eine schematische Darstellung des mit der Brennkraftmaschine verbundene Abgasturboladers;

Fig. 2

einen Teillängsschnitt durch den Radialverdichter des Abgasturboladers;

Fig. 3

eine Darstellung gemäss Fig. 2, jedoch in einem zweiten Ausführungsbeispiel;

Fig. 4

eine Darstellung gemäss Fig. 2, jedoch in einem dritten Ausführungsbeispiel;

Fig. 5

eine Darstellung gemäss Fig. 2, jedoch in einem vierten Ausführungsbeispiel;

Fig. 6

eine Darstellung gemäss Fig. 2, jedoch in einem weiteren Ausführungsbeispiel;

Fig. 7

eine Darstellung gemäss Fig. 2, jedoch in einem nächsten Ausführungsbeispiel.

Show it:

Fig. 1

a schematic representation of the engine connected to the exhaust gas turbocharger;

Fig. 2

a partial longitudinal section through the radial compressor of the exhaust gas turbocharger;

Fig. 3

a representation according to FIG 2, but in a second embodiment.

Fig. 4

a representation according to FIG 2, but in a third embodiment.

Fig. 5

a representation according to FIG. 2, but in a fourth embodiment;

Fig. 6

a representation according to FIG. 2, but in a further embodiment;

Fig. 7

a representation according to FIG. 2, but in a next embodiment.

Only the elements essential to the understanding of the invention are shown. The flow direction of the working means is indicated by arrows.

Way to carry out the invention

FIG. 1 shows, in a schematic illustration, one with a diesel engine trained internal combustion engine 1 cooperating exhaust gas turbocharger 2. The latter consists of a centrifugal compressor 3 and an exhaust gas turbine 4, which have a common shaft 5. The centrifugal compressor 3 is via a charge air line 6 and the exhaust gas turbine 4 via an exhaust pipe 7 with the internal combustion engine 1 connected. In the charge air line 6, i. between the centrifugal compressor 3 and the internal combustion engine 1, a charge air cooler 8 is arranged. The intercooler 8 has a cooling water circuit 9 with a not shown Supply and removal.

The centrifugal compressor 3 is equipped with a compressor housing 10 in which designed as a compressor wheel and connected to the shaft 5 rotor 11 is arranged is. The compressor wheel 11 has one with a plurality of blades 12 occupied hub 13. Between the hub 13 and the compressor housing 10th a flow channel 14 is formed. Downstream of the blades 12 connects the flow channel 14 a radially arranged, bladed diffuser 15, which in turn opens into a spiral 16 of the centrifugal compressor 3. The compressor housing 10 consists mainly of an air inlet housing 17, a Air outlet housing 18, a diffuser plate 19 and as an intermediate wall to a Bearing housing 21 of the exhaust gas turbocharger 2 formed stator 20 (FIG. 2).

The hub 13 has on the turbine side a rear wall 22 and a mounting sleeve 23 for the shaft 5 on. The fastening sleeve 23 is from the intermediate wall 20th received the compressor housing 10. Of course, another suitable Compressor wheel shaft connection can be selected. Likewise is also the Use of a bladed diffuser possible.

Between the rotating compressor wheel 11, i. its back wall 22 and the fixed intermediate wall 20 of the compressor housing 10 exists inevitably a separating gap which is formed as a radial gap 24 in a centrifugal compressor 3 is. The radial gap 24 takes a the compressor housing 10 opposite the bearing housing 21 sealing labyrinth seal 25. In the partition 20 of the compressor housing 10, a circumferential recess 26 is formed and with both a supply and with a discharge line 27, 28 for a Cooling fluid 29 connected (Fig. 2, Fig. 3). To the highest possible cooling effect to achieve adjacent compressor wheel 11, the intermediate wall 20 is the compressor wheel side the recess 26 formed as thin as possible. This is in the production the intermediate wall 20 a thin-walled and closed at both ends Poured tube 30 whose interior forms the recess 26 (Fig. 2).

During operation of the exhaust gas turbocharger 2, the compressor wheel 11 sucks as a working medium 31 ambient air, as a main flow 32 through the flow channel 14 and the diffuser 15 enters the spiral 16, there further compressed and finally via the charge air line 6 for charging with the exhaust gas turbocharger 2 connected internal combustion engine 1 is used. But before that happens in the intercooler 8 a corresponding cooling of the heated during the compression process Working medium 31.

On their way from the flow channel 14 to the diffuser 15 acts in the radial compressor 3 heated main flow 32 of the working medium 31 as a leakage flow 33 and the radial gap 24, whereby the compressor 11 in addition is heated. However, because the operating temperature in the outer region of the compressor wheel 11 is the largest, especially there occurs a large material load on. In the immediately adjacent to this critical area arranged recess 26 of the intermediate wall 20 is used as cooling fluid 29 from the cooling water circuit 9 of the intercooler 8 branched cooling water introduced. It comes thus to an indirect cooling of the radial gap 24 located in the leakage flow 33 and thus also the compressor wheel 11. In this case, the diversion takes place the cooling fluid 29 upstream of the intercooler 8, so that with the relatively cold cooling water effective cooling can be achieved. After the cooling process is the now heated cooling fluid 29 via the discharge line 28 downstream of the intercooler 8 fed back into the cooling water circuit 9 (Fig. 1). Naturally can instead of the system of internal combustion engine 1, intercooler 8 and Exhaust gas turbocharger 2 existing cooling water and fresh water from outside supplied to the system as cooling fluid 29 (not shown).

In a second embodiment, in which the radial gap 24 is not by means of a labyrinth seal 25, but with a between the mounting sleeve 23 and the intermediate wall 20 arranged sealing ring 34 is sealed, the formation of the recess 26 by one in the intermediate wall 20th cast-in core, which then has to be removed again (Fig. 3).

According to a third embodiment 20 is a groove in the intermediate wall 35 trained. In the groove 35 two tubes 36 are inserted and potted, wherein the two tubes 36 have a connecting line 37. Again form the Interiors of the tubes 36, the recess 26 (Fig. 4). Of course, in the groove 35 are arranged only a single tube 36. Likewise, in the intermediate wall 20 two or more grooves 35 are formed, which also can accommodate more than two tubes 36 (not shown).

As an alternative to the recess 26 in the intermediate wall 20 is in a fourth embodiment formed on the intermediate wall 20, a cavity 38, which on the turbine side is completed by a cover 39 (Fig. 5). Like the recess 26 is also the cavity 38 with a supply and with a discharge line 27, 28 connected for the cooling fluid 29. With this variant can be the realization the cooling of the compressor wheel 11 required manufacturing costs reduce advantageous. The lid 39 and thus also the cavity 38 can with the same function of course arranged on the compressor side of the intermediate wall 21 be (not shown).

In the latter embodiments, the indirect cooling of the located in the radial gap 24 leakage flow 33 and thus also the compressor wheel 11 substantially analogous to that described in the first embodiment Process.

In a further embodiment, the intermediate wall 20 is radially outward formed extended so that they are essential areas of the diffuser 15th covered. For this purpose, the intermediate wall 20 has a corresponding outer ring 43 on. In the interior of the outer ring 43, a circumferential cavity 44 is formed. The supply line 27 for the cooling fluid 29 engages the outer ring 43 and opens into the cavity 44, which other end with the recess 26th the intermediate wall 20 is connected (Fig. 6).

In this solution, the cooling fluid 29, starting from the supply line 27 first introduced into the cavity 44 of the outer ring 43, where it is the indirect Cooling of the diffuser 15 and the diffuser plate 19 is used. Only then does the Introduction of the cooling fluid 29 in the recess 26 of the intermediate wall 20. There the indirect cooling of the leakage flow 33, which has already been described above, takes place. The recirculation of the cooling fluid 29 into the cooling water circuit 9 also becomes realized via the discharge line 28.

Of course, the intermediate wall 20, as in the US 4815184, also directly into the Pass over diffuser plate 19 and with the recess 26 of the intermediate wall 20 connected cavity 44 may be disposed in the diffuser plate 19 (not shown).

In a next embodiment, in addition to the previously described indirect Cooling a direct cooling of the leakage flow 33 is provided. To are several tangential to the rear wall 22 of the compressor wheel 11 in the radial gap 24 opening feed channels 40 for a second cooling fluid 41 both the Bearing housing 21 and the diffuser plate 19 arranged penetrating (Fig. 7). The feed channels 40 are downstream of the intercooler 8 with the charge air line 6 connected, so that is used as the second cooling fluid 41 cooled charge air (Fig. 1).

Due to the tangential introduction of the second cooling fluid 41 is a pure film cooling realized the entire rear wall 22 of the compressor 11. The second Cooling fluid 41 replaces the hot leakage flow 33, so that at the Rear wall 22 of the compressor wheel 11 forming boundary layer already from the beginning is mainly formed by the cooled charge air. The following Derivation of the second cooling fluid 41 via a in the intermediate wall 20 of the Compressor housing 10 attacking, not shown discharge device 42. This combination of indirect and direct cooling has a special one Cooling effect, because the two cooling options complement each other in their effect and thus for a very high temperature reduction in the compressor 11th to care. Of course, other cooling media 41 may be used as the second cooling fluid 41 be, with an external supply of compressed air is possible (not shown).

FIG. 1 additionally shows the arrangement of a control valve 45 in the feed channel 40 for the second cooling fluid 41. With the help of this control valve 45, the quantitative Supply of the second cooling fluid 41 are regulated, so that an adjustment the cooling effect on the expected conditions or on the current temperature conditions during operation of the exhaust gas turbocharger 2 allows becomes. In this case, the control valve 45 also by hand as well as not shown Measuring and control unit are operated. questionable quantities are the temperature of the charge air after the intercooler 8 or the Temperature of the intermediate wall 20 itself. Of course, in this way the supply of the second cooling fluid 41 not only partially but also completely prevented become. In the latter case, then only indirect cooling, i. a water cooling takes place.

Of course, the cooling configurations described above can be arbitrary be combined with each other, regardless of whether in the radial gap 24, a labyrinth seal 25 is arranged or not. When using the partition wall cooling alone is from the outset any increase in the compressor thrust and the air leakage into the bearing housing 21 of the exhaust gas turbocharger 2 avoided.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

turbocharger

3

centrifugal compressors

4

exhaust turbine

5

wave

6

Turbo pipe

7

exhaust pipe

8th

Intercooler

9

Cooling water circuit

10

compressor housing

11

Rotor, compressor wheel

12

blade

13

hub

14

flow channel

15

diffuser

16

spiral

17

Air intake housing

18

Air outlet housing

19

diffuser plate

20

Stator part, intermediate wall

21

bearing housing

22

rear wall

23

mounting sleeve

24

Radial gap, separating gap

25

labyrinth seal

26

recess

27

supply line

28

discharge line

29

cooling fluid

30

pipe

31

working medium

32

mainstream

33

leakage flow

34

sealing ring

35

groove

36

pipe

37

connecting line

38

cavity

39

cover

40

feed

41

second cooling fluid, charge air

42

removal device

43

outer ring

44

cavity

45

Control valve

Claims (10)

1. Method for cooling the flow in radial gaps formed between rotors and stators of turbomachines, a leakage flow (33) branching off from a main flow (32) of a working medium (31) of the turbomachine and flowing into the radial gap (24), in which method a first cooling fluid (29) is admitted to a stator part (20) adjacent to the radial gap (24), characterized in that the main flow (32) of the working medium (31) is directed into a diffuser (15) downstream of the branching-off point of the leakage flow (33), and in that the first cooling fluid (29), before it is admitted to the stator part (20) adjacent to the radial gap (24), is used for the indirect cooling of the diffuser (15) and a diffuser plate (19), water being used as first cooling fluid (29), and in that a second cooling fluid (41) is directed into the radial gap (24).
2. Method according to Claim 1, characterized in that the feeding of the second cooling fluid (41) is partly shut off, and air is preferably used as second cooling fluid.
3. Method according to Claim 1 or 2, characterized in that the first cooling fluid (29) is introduced into a recess (26) formed in the stator part (20) or into a cavity (38) arranged at the stator part (20).
4. Method according to Claim 3, characterized in that fresh water from outside a system consisting of an internal combustion engine (1), a charge-air cooler (8) and an exhaust-gas turbocharger (2) is used as first cooling fluid (29).
5. Method according to Claim 3, characterized in that water present in a system consisting of an internal combustion engine (1), a charge-air cooler (8) and an exhaust-gas turbocharger (2) is used as first cooling fluid (29) .
6. Method according to Claim 5, characterized in that cooling water present in a cooling-water circuit (9) of the charge-air cooler (8) is used as first cooling fluid (29) and the latter is branched off upstream of the charge-air cooler (8).
7. Arrangement for carrying out the method according to Claim 1, in which a fixed stator part (20) is arranged so as to define the radial gap (24) relative to the rotor (11), characterized in that at least one recess (26) is formed in the interior of the stator part (20) or at least one cavity (38) is arranged at the stator part (20), and the recess (26) or the cavity (38) is connected to both a feed line (27) and a discharge line (28) for a cooling fluid (29) and in that at least one feed passage (40) as well as a discharge device (42) for a second cooling fluid (41) are arranged at the radial gap (24).
8. Arrangement according to Claim 7, characterized in that at least one integrally cast tube (30) is arranged in the stator part (20).
9. Arrangement according to Claim 7, characterized in that at least one groove (35) is arranged in the stator part (20), and at least one tube (36) is inserted and encapsulated in each groove (35).
10. Arrangement according to Claim 7, characterized in that the fixed stator part (20) is designed as part of a compressor casing (10) of a radial compressor (3), and this part bounds the radial gap (24) relative to a rotating compressor impeller (11) of an exhaust-gas turbocharger (2).

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