EP0903465A1 - Compressor wheel-shaft connection for high speed turbomachinery - Google Patents

Abstract

The device has a hub cone (9) and shaft cone (11), each with average diameter (23, 24). The diameters are located at an axial distance (25) to the center of gravity (14) of the compressor impeller (4), which corresponds to at least half the average diameter. The passage bore (8) in the hub (6) is formed at least partially as a cylindrical bore (16) on the shaft side of the hub cone.

Description

Technical field

The invention relates to a compressor wheel attachment for high-speed turbomachinery according to the preamble of claim 1.

State of the art

Compressor wheels of turbomachinery are either non-positive or positive connected to their drive shaft. With increasing pressure conditions and consequently with increasing operating torques and high peripheral speeds is a positive torque transmission, i.e. a form-fitting Shaft-hub connection of the compressor wheel advantageous.

A positive compressor wheel attachment is known from EP 05 22 630 B1, which is realized by means of a multi-spline shaft. With this solution it is Lifespan of the shaft-hub connection due to the insertion through the keyways Notches restricted. In addition, additional centering elements are required which increase the cost of the compressor wheel. As a result of the manufacturing-related Such a shaft-hub connection must have inaccuracies of multi-spline shafts always be balanced as a unit, the parts being identical for the purpose Reassembly must be marked accordingly. So the stake is of the compressor wheel with another, not balanced together with this Wave not possible. However, this is a crucial disadvantage when servicing.

Positive compressor wheel attachments using a thread are both from US 3,961,867 and also from WO 93/022778. Are disadvantageous manufacturing inaccuracies of the thread. Furthermore require the high operating torques generated by compressor wheels high tightening or loosening torques. Especially with larger compressor wheels the loosening torques required for disassembly reach double the Operating torque. Such forces can only be achieved using special tools or be applied by means of a transmission gear. However, this increases clearly the effort required to dismantle compressor wheels. A there is another disadvantage of fastening the compressor wheel by means of a thread in that when assembling the compressor wheel the first with the shaft thread touching areas of the hub thread up to their End position must travel a relatively long way on the shaft thread. Because the threads involved have little play, the result is a relatively strong one Pressure between the individual thread parts, i.e. in an area without any Lubrication. As a result, so-called erosion or Deformation of the threads so that different results are obtained with each new assembly can be achieved. Such a connection is therefore not sufficiently reproducible. In addition, these solutions are compressor wheels with a Blind bore that does not have compressor wheels with regard to its shaft-hub connection can be compared that have a through hole.

According to the "Information on the use of polygon connections", from FORTUNA-WERKE Maschinenfabrik AG, Stuttgart-Bad Cannstatt a spur pinion shaft and a compressor impeller for the blower of a cooling system known. Point to the non-rotatable connection of the compressor wheel on the shaft both components have a conical profile with a polygonal base, whereby the shaft cone is arranged on the shaft end. The wave and the Hub cone, i.e. the actual connection point between the shaft and the compressor wheel, are on the compressor side of the rear wall of the compressor wheel and thus in the center of mass arranged of the compressor wheel. This area of highest stress concentration inevitably experiences the largest when the turbocharger is in operation Widening, so that the security of the connection with increasing peripheral speed of the compressor wheel drops. High-speed turbo machines, such as for example turbochargers, reach peripheral speeds of 500 m / s and about that. Such peripheral speeds place significantly higher demands the torque transmission and the safety of the shaft-hub connection. These requirements can be met with the conventional state of the art Technology cannot be met.

Presentation of the invention

The invention tries to avoid all of these disadvantages. You have the task based on a safe and reproducible compressor wheel attachment for high-speed To create turbo machines, which also have an improved torque transmission owns.

According to the invention this is achieved in that both in the through hole of the compressor wheel arranged hub cone as well as the corresponding one Shaft cone each have an average diameter and these mean diameters at an axial distance from the center of mass of the compressor wheel are arranged, which is at least half the middle Corresponds to diameters. The through hole of the hub is on the shaft side of the hub cone is at least partially designed as a cylindrical bore.

With this arrangement, the hub and shaft cones, i.e. the real ones Fastening elements, outside the center of gravity of the compressor wheel. Therefore are essential in the fastening area of the compressor wheel to record minor stresses due to centrifugal forces or thermal expansion, so that the widening of the hub cone can be significantly reduced. This means that compressor wheel attachment can be secured even at high speeds will be realized. The cylindrical bore arranged on the shaft side serves as Centering seat for the compressor wheel.

The through bore of the hub on both sides of the hub cone is particularly advantageous at least partially formed as a cylindrical bore, the second, i.e. the cylindrical bore on the compressor side is an assembly aid.

In a first embodiment, the compressor wheel has one on its rear wall connecting sleeve on the shaft side for the shaft journal. Here are the hub cone in the mounting sleeve and the cylindrical bores on both sides, i.e. arranged on the shaft or compressor side of the hub cone. With this The distance can be particularly suitable for internally mounted turbochargers the fasteners from the center of gravity of the compressor wheel be further enlarged. This leads to an improved compressor wheel attachment, which allows higher speeds without risk.

On the shaft side of the hub, a flat surface is advantageous on the mounting sleeve and a corresponding plan stop is formed on the shaft. So that both clear axial positioning as well as good concentricity of the compressor wheel reached.

The shaft journal is formed at least in two parts and consists of the shaft cone as well as one with the centering seat, i.e. with the shaft-side cylindrical Bore, corresponding shaft collar. Alternatively to the two-part Training, the shaft journal is formed at least in three parts. He points to that additionally a cylindrical shaft end, which pre-rivets the compressor wheel serves to position it on the shaft journal. As a result of this There is no radial displacement when the compressor wheel is pre-centered of the shaft and the hub cone against each other, so that a Damage to the actual fasteners can be avoided. Ultimately, this leads to an improved shaft-hub connection and thus an increased service life of the compressor wheel.

At least in the through hole of the compressor wheel and in the shaft journal one mounting device each for an assembly / disassembly tool arranged. This allows the compressor wheel to be relative from the compressor side can be easily assembled or disassembled. The receiving device is particularly advantageous of the shaft journal in the shaft end, with a two-part shaft journal however arranged in the shaft cone. The receiving devices are as internal threads formed, the internal thread of the shaft end or the shaft cone is smaller than the internal thread of the hub. The assembly / disassembly tool is different as a differential screw with two external threads Incline trained. The one that corresponds to the smaller slope corresponds External thread with the internal thread of the hub and the one with the larger one Inclined external thread with the internal thread of the shaft end or the shaft cone.

The differential screw or its differential thread serves both as an assembly / disassembly tool as well as for axially securing the compressor wheel the wave. Accordingly, no additional assembly / disassembly tools are required.

In a second embodiment of the invention, the hub cone is on the compressor side the center of gravity of the compressor wheel. This will make it Compressor wheel less stressed by centrifugal forces or thermal expansion than with the arrangement of the hub cone in the center of mass. With this, in particular suitable for the external storage of turbochargers Widening of the hub cone is reduced even further and thus the fastening of the Compressor wheel can be further improved. In addition, a smaller axial length reached.

With this solution, at the hub, on the compressor side of the center of gravity, a plane surface is formed and the shaft has a corresponding plan stop on. In this area of the compressor wheel they occur in comparison other areas at the lowest temperatures, so that no large surface pressures are to be expected from axial thermal expansion. Therefore the service life of the shaft-hub connection can be increased.

Brief description of the drawing

In the drawing, several embodiments of the invention are based on the Compressor of an exhaust gas turbocharger shown.

Fig. 1

einen Teillängsschnitt durch einen innengelagerten Abgasturbolader, im Bereich des Verdichterrades;

Fig. 2

einen Schnitt II-II durch das Verdichterrad gemäss Fig. 1, im Bereich des Wellenkonus (vergrössert dargestellt);

Fig. 3

einen Teillängsschnitt durch einen innengelagerten Abgasturbolader, entsprechend einem zweite Ausführungsbeispiel;

Fig. 4

einen Teillängsschnitt durch einen aussengelagerten Abgasturbolader, im Bereich des Verdichterrades.

Show it:

Fig. 1

a partial longitudinal section through an internally mounted exhaust gas turbocharger, in the region of the compressor wheel;

Fig. 2

a section II-II through the compressor wheel according to Figure 1, in the region of the shaft cone (shown enlarged).

Fig. 3

a partial longitudinal section through an internally mounted exhaust gas turbocharger, according to a second embodiment;

Fig. 4

a partial longitudinal section through an externally mounted exhaust gas turbocharger, in the area of the compressor wheel.

Only the elements essential for understanding the invention are shown. The turbine side of the exhaust gas turbocharger, for example, is not shown and the internal combustion engine connected to the latter.

Way of carrying out the invention

The exhaust gas turbocharger mainly consists of a radial compressor Compressor 1 and an exhaust gas turbine, not shown, which on a common shaft 2 are arranged. The radial compressor 1 has a compressor housing 3, in which a compressor wheel 4 is rotatably mounted on the shaft 2. The compressor wheel 4 has one with a large number of blades 5 Hub 6 on. In the hub 6 is a central shaft 7 receiving the shaft 2 Through hole 8 introduced (Fig. 1). The through hole 8 is partially designed as a hub cone 9 with a polygonal base 10 (Fig. 2). The shaft journal 7 takes one corresponding to the hub cone 9 Wave cone 11, which in turn also has a polygonal Base area 12 has.

The hub 6 of the compressor wheel 4 is equipped on the shaft side with a rear wall 13. On the compressor side of the rear wall 13, the compressor wheel 4 has a center of mass 14. The through hole 8 is on both sides of the hub cone 9 formed as a cylindrical bore 15, 16. Both holes 15, 16 are coaxial to an axis 17 of the through hole 8.

Of course, the solution according to the invention can also be used with an exhaust gas turbocharger can be used with a compressor 1 designed as an axial compressor (not shown).

In a first embodiment, the exhaust gas turbocharger has an inner bearing, i.e. between the turbine or between its likewise not shown Housing and the compressor housing 3 is a bearing housing 18 with an axial / radial bearing 19 arranged in which the shaft 2 is rotatably mounted. To the Rear wall 13 of the hub 6 closes a fastening bushing 20 on the shaft side the shaft journal 7. While the mounting sleeve 20 with a flat surface 21 closes, the shaft 2 has a corresponding face stop 22. Either the hub cone 9 and the shaft cone 11 are in the mounting sleeve 20 arranged. They each have an average diameter 23, 24 and are at an axial distance 25 from the center of gravity 14 of the compressor wheel 4 arranged, which is at least half its average diameter 23, 24 corresponds. There is one of the cylindrical ones on each side of the hub cone 9 Bores 15, 16 formed.

The axial / radial bearing 19 consists of a on the bearing housing 18 by means of screws 26 fixed and therefore fixed bearing body 27 and a non-rotatable with the shaft 2 connected bearing comb 28. That becomes the compressor wheel 4 Axial / radial bearing 19 from an intermediate element designed as an auxiliary bearing disc 29 completed, which compressor side another stop 30 for has the mounting sleeve 20. Between the bearing housing 18 and the Compressor housing 3, an intermediate wall 31 is arranged and by means of fastening screws 32 fixed to the bearing housing 18. The intermediate wall 31 takes the Fastening sleeve 20 of the hub 6 of the compressor wheel 4 and is opposite this is sealed, for example, by means of a labyrinth seal (not shown).

The shaft journal 7 is in three parts and consists of a cylindrical shaft end 33, the shaft cone 11 and a cylindrical one adjoining the shaft 2 Wave collar 34. The shaft cone has on the shaft end 33 side 11 its smallest diameter (Fig. 1).

Both the shaft end 33 of the shaft journal 7 and the hub 6 are on their end on the compressor side, each with an internal thread Receiving device 35, 36 for an assembly / disassembly tool designed as a differential screw 37 of the compressor wheel 4 provided. This is the internal thread 35 of the shaft end 33 is formed smaller than the internal thread 36 of the Hub 6. The differential screw 37 has two external threads 38, 39 different Size and different slope. The larger external thread 38 has the smaller pitch and corresponds to the internal thread 36 of the hub 6, while the one with the larger pitch is smaller External thread 39 cooperates with the internal thread 35 of the shaft end 33. In addition, the differential screw 37 has a hexagon socket Recording 40 for an actuator, not shown.

Of course, it is possible to use the larger external thread 38 with the larger and to provide the smaller external thread 39 with the smaller pitch, which at the assembly opposite to the solution shown in Fig. 1 Rotation of the assembly / disassembly tool 37 requires. Of course can also be another assembly / disassembly tool 37 for the compressor wheel 4th are used, for example a hydraulic device.

When installing the compressor wheel 4, the differential screw 37 is first about a third screwed into the compressor wheel 4. Then will the compressor wheel 4 pushed over the cylindrical shaft end 33 until the differential screw 37 with its smaller external thread 39 on the internal thread 35 of the shaft end 33 abuts. Then the differential screw 37 with the help of Actuating element rotated until the compressor wheel 4 with its flat surface 21 is present at stop 30. At this point, the reverse thrust serving as the tread of the axial / radial bearing 19 auxiliary bearing plate 29 between the face stop 22 of the shaft 2 and the face surface 21 of the compressor wheel 4 trapped. During the winding of the compressor wheel 4 over the different Slope of the external thread 38, 39 can be realized by the different Diameter of the external thread 38, 39 incorrect installation of the Differential screw 37 and thus damage to the thread from the outset be excluded. The differential screw 37 also remains in operation of the exhaust gas turbocharger in the through hole 8 and forms an additional axial securing for the compressor wheel 4. For this purpose the actuating element after assembly of the compressor wheel 4 from the hexagon socket 40 of the Differential screw 37 removed. The disassembly of the compressor wheel 4 is in in reverse order.

According to a second exemplary embodiment, the exhaust gas turbocharger also has an internal storage. In contrast to the first embodiment, the shaft journal is 7, however, only formed in two parts and consists of the shaft cone 11 and from the corresponding with the shaft-side cylindrical bore 16 Wavy collar 34 (Fig. 3). In this case, the one designed as an internal thread Receiving device 35 arranged inside the shaft cone 11, which is why an appropriately adapted assembly / disassembly tool 37 ', i.e. a extended differential screw is used. This will be an alternative Fastening variant for the compressor wheel 4 provided, the Assembly / disassembly takes place analogously to the first embodiment.

In a third exemplary embodiment, the exhaust gas turbocharger has an upstream the compressor wheel 4 arranged external bearing, of which only one bearing housing 18 'are shown with a seal 41. Both the hub cone 9 and the shaft cone 11 are formed on the compressor-side end of the compressor wheel 4. The two cylindrical bores 15, 16 of the hub 6 are on the shaft side the hub cone 9 is arranged. They have the same diameter and go into each other at the center of gravity 14 of the compressor wheel 4. Of the Shaft journal 7 is in three parts and consists of a cylindrical shaft end 33 ' for receiving a mounting / securing element designed as a threaded bush 37 '', the shaft cone 11 and a cylindrical one adjoining the shaft 2 Wavy collar 34 '. In contrast to the first embodiment corresponds the shaft collar 34 'therefore has two cylindrical bores 15, 16 the hub 6. On the shaft side of the hub cone 9, the hub 6 has a flat surface 21 ' on, which with a correspondingly designed plan stop 22 'of the shaft collar 34 'cooperates (Fig. 4).

For assembly, the compressor wheel 4 is first pushed onto the shaft journal 7 and then by means of the threaded bush 37 '' on the shaft cone 11 raised. When the flat surface 21 'in contact with the plan stop 22' comes, the required shaft-hub connection is established.

Reference list

1

compressor

2nd

wave

3rd

Compressor housing

4th

Compressor wheel

5

Blade

6

hub

7

Shaft journal

8th

Through hole

9

Hub cone

10th

polygonal base, from 9

11

Shaft cone

12th

polygonal base, from 11

13

Back wall, from 6

14

Center of gravity, from 4

15

cylindrical bore

16

cylindrical bore, centering seat

17th

axis

18th

Bearing housing

19th

Axial / radial bearings

20th

Mounting sleeve

21

Flat area

22

Planning stop

23

medium diameter, from 9

24th

medium diameter, from 11

25th

Distance, axial

26

screw

27

Bearing body

28

Storage comb

29

Intermediate element, auxiliary bearing washer

30th

attack

31

Partition

32

Fastening screw

33

cylindrical shaft end, from 7

34

cylindrical shaft collar

35

Holding device, internal thread

36

Holding device, internal thread

37

Assembly / disassembly tool, differential screw

38

larger external thread, from 37 or 37 '(with a smaller pitch)

39

smaller external thread, from 37 or 37 '(with a larger pitch)

40

Recording, hexagon socket

41

poetry

18 '

Bearing housing

21 '

Flat area

22 '

Planning stop

33 '

cylindrical shaft end

34 '

cylindrical shaft collar

37 '

Assembly / disassembly tool, differential screw (extended)

37 ''

Mounting / securing element, threaded bush

Claims (11)

Compressor wheel attachment for high-speed turbomachinery, with a compressor wheel (4) attached to a shaft (2), which consists of a hub (6) with several blades (5) and a rear wall (13) and one on the compressor side of the rear wall (13) Center of mass (14), the hub (6) being provided with a central through bore (8) for receiving a shaft journal (7) of the shaft (2) and the through bore (8) at least partially as a hub cone (9) with a polygonal base area ( 10), the shaft journal (7) has a shaft cone (11) which interacts with the hub cone (9) and the latter has a polygon-like base surface (12) corresponding to the base area (10) of the hub cone (9), characterized in that a) both the hub cone (9) and the shaft cone (11) each have an average diameter (23, 24) and these average diameters (23, 24) at an axial distance (25) from the center of gravity (14) of the compressor wheel (4 ) are arranged, which corresponds to at least half the average diameters (23, 24), b) the through bore (8) of the hub (6) on the shaft side of the hub cone (9) is at least partially designed as a cylindrical bore (16), Compressor wheel attachment according to claim 1, characterized in that the through bore (8) of the hub (6) on both sides of the hub cone (9), is at least partially designed as a cylindrical bore (15, 16). Compressor wheel attachment according to claim 2, characterized in that the hub (6) of the compressor wheel (4) on the shaft side to the rear wall (13) has a connecting sleeve (20) for the shaft journal (7), wherein the hub cone (9) in the mounting sleeve (20) and the cylindrical bores (15, 16) arranged on both sides of the hub cone (9) are. Compressor wheel attachment according to claim 3, characterized in that on the shaft side of the hub (6) a flat surface (21) on the mounting sleeve (20) is formed and the shaft (2) has a corresponding plan stop (22). Compressor wheel attachment according to claim 4, characterized in that the shaft journal (7) is formed at least in two parts and from the shaft cone (11) and one with the shaft-side cylindrical bore (16) corresponding shaft collar (34). Compressor wheel attachment according to claim 4, characterized in that the shaft journal (7) is constructed in at least three parts and consists of the shaft cone (11), one corresponding to the shaft-side cylindrical bore (16) Wave collar (34) and a cylindrical shaft end (33) exists. Compressor wheel attachment according to claim 5 or 6, characterized in that that in the shaft journal (7) and in the through hole (8) at least each have a receiving device (35, 36) for a preferably as Differential screw with two external threads (38, 39) different Incline mounting / dismounting tool (37, 37 ') of the compressor wheel (4) is arranged. Compressor wheel attachment according to claim 7, characterized in that both receiving devices (35, 36) are designed as internal threads, the receiving device (35) of the shaft journal (7) in the shaft end (33) arranged and smaller than that in the through bore (8) of the hub (6) arranged receiving device (36) is formed. Compressor wheel attachment according to claim 7, characterized in that both receiving devices (35, 36) are designed as internal threads, the receiving device (35) of the shaft journal (7) in the shaft cone (11) arranged and smaller than that in the through bore (8) of the hub (6) arranged receiving device (36) is formed. Compressor wheel attachment according to claim 1, characterized in that the hub cone (9) upstream of the center of mass (14) of the compressor wheel (4) is arranged. Compressor wheel attachment according to claim 10, characterized in that that on the compressor side of the center of mass (14) there is a flat surface (21 ') is formed on the hub (6) and the shaft (2) a corresponding Has plan stop (22 ').

Images