CN104126063A - Exhaust-gas turbocharger - Google Patents

Abstract

The invention relates to an exhaust-gas turbocharger (1) having a shaft (2), which has a first centric bore (4) on an end face (3), having a turbine wheel (5), which has a second centric bore (7) in the wheel rear side (6) thereof, having a connection piece (8), which engages into the first and second bores (4, 7); and having an integral connection device (9) for connecting the shaft (2) to the turbine wheel (5), wherein the connection piece (8) is hollow in form.

Description

exhaust turbocharger

The invention relates to an exhaust-gas turbocharger according to the preamble of claim 1 .

An exhaust-gas turbocharger of this type is known from DE 10 2009 034420 A1. In order to connect the turbine wheel of this known exhaust-gas turbocharger to a steel shaft, it is provided that a hole is made both in the wheel rear side of the turbine wheel and in the end face of the shaft, in which hole A metallic centering pin is inserted, the coefficient of thermal expansion of which substantially corresponds to the coefficient of thermal expansion of the ceramic turbine wheel. Furthermore, a brazed connection is provided to connect the shaft to the turbine wheel.

The disadvantage of this arrangement is that the centering pin forms a thermal bridge and therefore a large amount of heat is introduced into the shaft from the turbine wheel.

It is therefore an object of the present invention to provide an exhaust-gas turbocharger of the type indicated in the preamble of claim 1 which makes it possible to achieve thermal throttling between the turbine wheel and the shaft .

This object is achieved by the features of claim 1 .

It is provided according to the invention that the connection inserted in the holes in the turbine wheel and the shaft is in hollow form. Thus, a kind of air space is formed in the connection which acts as a thermal throttle. The connecting piece can in this case be in the form of a perforated sleeve or a clamping sleeve.

The connection thus performs the task of heat confinement and of a centering element between the turbine wheel and the shaft.

The dependent claims relate to advantageous developments of the invention.

In particular, the connecting piece can be in the form of a cylindrical part or a part with an angular cross-section. In the latter case, in addition to the one-piece connection, there is also a form fit between the turbine wheel and the shaft.

In principle, a soldered connection, an adhesive bonded connection or another welded connection is conceivable as a one-piece connection.

Claims 9 and 10 define a rotor according to the invention for an exhaust-gas turbocharger as an object that can be marketed independently.

Further details, advantages and features of the invention will become apparent from the following description of several exemplary embodiments with reference to the accompanying drawings, in which:

Figure 1 shows a greatly simplified schematic basic representation of an exhaust-gas turbocharger according to the invention, and

FIG. 2 shows a partial section through the shaft and the turbine wheel of the rotor of an exhaust-gas turbocharger according to the invention, taken in the region of the attachment point between the turbine wheel and the shaft.

FIG. 1 shows an exhaust-gas turbocharger 1 with a shaft 2 in a greatly simplified schematic representation. A turbine wheel of a turbine 4 is arranged at one end of this shaft 2 . The other end of the shaft 2 is equipped with a compressor wheel 10 of a compressor 11 . A bearing housing 12 for mounting the shaft 2 is arranged between the compressor 11 and the turbine 4 . Of course, the exhaust-gas turbocharger according to the invention also has all other components of such a supercharger, but these are not shown or explained because they are not necessary for explaining the principles of the invention.

As shown in detail in FIG. 2 , the shaft 2 has a first central bore 4 on the end face 3 facing the turbine wheel 5 .

The turbine wheel 5 has a second central bore 7 in its wheel rear side 6 . These holes 4 and 7 are arranged in alignment with the longitudinal axis L of the exhaust-gas turbocharger 1 . In the illustrated embodiment, the wheel rear side 6 of the turbine wheel 5 is in the form of a shoulder protruding axially in the direction towards the shaft 2 . However, it is also possible that the impeller rear side 6 is formed with a smooth surface.

As shown in FIG. 2 , a connecting piece 8 is provided which, in the assembled state shown in FIG. 2 , engages into the first hole 4 and the second hole 7 . For connecting the turbine wheel 5 to the shaft 2 there is also provided a one-piece connection 9 which, as explained in the preamble, can be in the form of a soldered connection, for example.

FIG. 2 shows that the connecting piece 8 is in the form of a hollow sleeve with an annular space 13 accommodating an air cushion as a heat choke. The connecting element 8 thus acts both as a centering element and as a thermal restriction, which reduces the heat introduced into the shaft 2 from the turbine wheel 5 . In this respect, it is of course possible to adapt the length and diameter of the connecting piece 8 to the respective application in order to achieve the greatest possible thermal throttling effect. Furthermore, it is also conceivable in principle to extend the bores 4 and 7 beyond the length of the connecting piece 8 in order to lengthen the air space 13 beyond the connecting piece 8 .

Correspondingly, the connecting piece 8 can be in the form of a perforated sleeve or a hollow clamping sleeve.

It can have a cylindrical cross-section or an angular cross-section in order to achieve a form-fit connection in addition to the one-piece connection.

The turbine wheel is preferably formed from titanium aluminide (TiAl). The shaft 2 is preferably in the form of a steel shaft.

In addition to the above written disclosure of the invention, express reference is hereby made to Figures 1 and 2 to supplement this disclosure.

List of reference symbols

1 exhaust turbocharger

2 axis

3 end faces

4 The first center hole

5 turbine wheel

6 rear side of the impeller

7 Second center hole

8 connectors

9 One-piece connection device

10 compressor impeller

11 compressor

12 bearing housing

L Supercharger longitudinal axis

Claims (10)

1. An exhaust turbocharger (1) - having a shaft (2) with a first central hole (4) on an end face (3); - having a turbine wheel (5) having a second central hole (7) in its wheel rear side (6); - having a connecting piece (8) engaging into the first and second holes (4, 7); and - having an integral connection (9) for connecting the shaft (2) to the turbine wheel (5), in - The connecting piece (8) is of hollow form. 2. The exhaust-gas turbocharger as claimed in claim 1, wherein the connecting piece (8) is in the form of a perforated sleeve. 3. The exhaust-gas turbocharger as claimed in claim 1, wherein the connecting piece (8) is in the form of a hollow clamping sleeve. 4. The exhaust-gas turbocharger as claimed in one of claims 1 to 3, wherein the connecting piece (8) has a cylindrical cross-section. 5. The exhaust-gas turbocharger as claimed in one of claims 1 to 3, wherein the connecting piece (8) has an angular cross-section. 6. The exhaust-gas turbocharger as claimed in one of claims 1 to 5, wherein the turbine wheel (5) is formed from TiAl material. 7. The exhaust-gas turbocharger as claimed in one of claims 1 to 6, wherein the shaft (2) is formed from steel. 8. The exhaust-gas turbocharger as claimed in one of claims 1 to 7, wherein the one-piece connection (9) is a soldered connection, an adhesive bonded connection or a welded connection. 9. A rotor of a compressor (1) of an exhaust turbocharger, - having a shaft (2) with a first central hole (4) on an end face (3); - having a turbine wheel (5) having a second central hole (7) in its wheel rear side (6); - having a connecting piece (8) engaging into the first and second holes (4, 7); and - having an integral connection (9) for connecting the shaft (2) to the turbine wheel (5), in - The connecting piece (8) is of hollow form. 10. A rotor according to claim 9, characterized by one of claims 2 to 8.