An exhaust-gas turbocharger (1) with a compressor wheel (2); with a turbine wheel (3); and with a shaft (4) on which the compressor wheel (2) and the turbine wheel (3) are arranged in a rotationally secured manner. The turbine wheel (3) has a through-opening (5) in which a first end region (6) of the shaft (4) is arranged, and the turbine wheel (3) is braced between an end-side stop (7) connected to the end region (6) and a compressor wheel-side shaft sleeve (8) fixed on the shaft (4).

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an exhaust-gas turbocharger.

Description of the Related Art

In the case of an exhaust-gas turbocharger of the generic type, the turbine wheel is brazed or welded to the shaft, possibly causing problems under certain circumstances during mounting owing to thermal distortion and moreover being relatively complicated.

It is therefore the object of the present invention to provide an exhaust-gas turbocharger of the type specified in the preamble of claim1in which the turbine wheel can be securely connected to the shaft in a technically simple manner without a material bond.

BRIEF SUMMARY OF THE INVENTION

This object is achieved by the features of claim1.

According to the invention, the turbine wheel, in particular in the form of a TiAl turbine wheel, is provided with a through-opening or through-bore and can accordingly be pushed onto the shaft up to a stop fixed on the shaft. A shaft sleeve can then be slid onto the shaft, by means of which the turbine wheel can be securely fixed on the shaft in a different manner.

Here, one end side of the shaft sleeve serves as an abutment on the turbine wheel and the other end side of the sleeve functions as a shaft shoulder for a shaft assembly arranged on the shaft. The large length of this shaft assembly makes it possible to achieve a good tension rod effect.

Consequently, the arrangement according to the invention of the exhaust-gas turbocharger requires neither a brazing nor a welding operation.

In addition to the advantages already mentioned above, there results the advantage that the rotor formed by the shaft assembly and the shaft can be machined if required after mounting the shaft sleeve.

Furthermore, the arrangement according to the invention allows the production of a heat throttle and there results a simple handling of the entire arrangement during its mounting.

There further results the advantage that the dimensions of the exhaust-gas turbocharger or of its rotor are not changed, with the result that the rotor according to the invention can be mounted in existing model ranges.

The subclaims contain advantageous developments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Here, the single FIGURE of the drawing shows a longitudinal section through an exhaust-gas turbocharger according to the invention, and, to simplify the illustration, only half of the components of the exhaust-gas turbocharger arranged above the turbocharger axis A are illustrated without compressor and turbine housings.

Accordingly, the exhaust-gas turbocharger1has a compressor wheel2and a turbine wheel3which are each arranged in a rotationally secured manner on a shaft4.

According to the invention, to avoid the need for a brazed or welded connection, the turbine wheel3has a through-opening5. By pushing the turbine wheel3onto the shaft4, a first end region6of the shaft4is arranged inside the through-opening5.

The FIGURE further shows that the turbine wheel3is arranged between a non-threaded end-side stop7permanently fixed on the end region6and a shaft sleeve8which is arranged on the shaft4on the compressor wheel side.

To secure against rotation, the turbine wheel3can be provided, for example, with a polygon arrangement (not shown in further detail in the FIGURE) which provides complementary polygon shapes in the through-opening5and on the end region6of the shaft4. Alternatively, there could be provided an end-side positive-locking device, for example in the form of a pin-hole arrangement in which retaining pins22, of which only one is shown inFIG. 1, are provided either in an end of the turbine wheel3or the adjacent side of the end stop7and pin-holes in which the pins of the pin arrangement engage are provided in the respective other part.

In order to brace the turbine wheel3, different possibilities according to the principles of the present invention are provided.

One alternative is screwing the shaft sleeve8on the shaft4or pressing the shaft sleeve8by means of a press fit on the shaft4. With this option, the turbine wheel3is braced between the stop7and an end face8A of the shaft sleeve8. In this case, the other end side or end face8B of the shaft sleeve8forms a shaft shoulder for a shaft assembly9which, in the case of the example illustrated, comprises the compressor wheel2, a sealing bush10adjoining the latter in the direction of the turbine wheel3, a bearing collar11adjoining the latter, a bush13in turn adjoining the latter and a bearing collar12which in turn adjoins the latter and which in the final mounting state bears against the end face8B, as is evident in detail from the FIGURE.

As an alternative to the aforementioned bracing of the turbine wheel3on the shaft4, it is possible for the shaft sleeve8to be applied loosely to the shaft4and braced via the aforementioned shaft assembly9. For this purpose, a shaft nut14can be provided which bears against an outwardly directed end face2A of the compressor wheel2and can thus brace the turbine wheel3via the compressor wheel2and the aforementioned shaft assembly9and also the shaft sleeve8applied loosely on the shaft4. Particularly with this arrangement there is also a very good tension rod effect and hence a very secure bracing both of the turbine wheel3and the compressor wheel2which likewise has a through-opening16such that it can also be pushed onto the shaft4.

In addition to the aforementioned advantages of simplified mounting and avoidance of a material bond, the aforementioned design according to the invention of the exhaust-gas turbocharger1affords the possibility of providing a heat throttle15in the end region6of the shaft4.

The above-described embodiment is particularly advantageous if the material of the compressor wheel3is titanium aluminide.

In addition to the written disclosure above, reference is hereby explicitly made, to supplement the disclosure of the invention, to the graphic representation of the single FIGURE.

LIST OF REFERENCE SIGNS

1Exhaust-gas turbocharger2Compressor wheel2A Outer end face of the compressor wheel23Turbine wheel4Shaft5Through-opening6First end region of the shaft47Stop8Shaft sleeve8A,8B End faces or end sides of the shaft sleeve9Shaft assembly10Sealing bush11,12Bearing collars13Bush between the bearing collars14Shaft nut15Heat throttle16Through-opening of the compressor wheel217Second end region of the shaft418Axial bearing arrangement19Sealing bush portion of the shaft sleeve820Bearing housing21Heat shieldA Turbocharger axis