Turbomachine

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a turbomachine.

2. Description of the Related Art

The fundamental construction of a turbocharger is known to the person skilled in the art addressed here. A turbocharger comprises a turbine, in which a first medium is expanded. Furthermore, a turbocharger comprises a compressor, in which a second medium is compressed, namely utilizing the energy extracted in the turbine during the expansion of the first medium. The turbine of the turbocharger comprises a turbine housing and a turbine rotor. The compressor of the turbocharger comprises a compressor housing and a compressor rotor. Between the turbine housing of the turbine and the compressor housing of the compressor a bearing housing is positioned, wherein the bearing housing on the one hand is connected to the turbine housing and on the other hand to the compressor housing. In the bearing housing, a shaft is mounted via which the turbine rotor is coupled to the compressor rotor.

From DE 101 37 899 C1 a turbine of a turbocharger designed as axial turbine is known, which comprises a diffuser which follows the turbine impeller and is limited by an inner shell and an outer shell. Seen in the flow direction of the exhaust gas, a collection chamber follows the diffuser, wherein the diffuser in the radial direction merges into the collection chamber with a mouth cross section or leads into the collection chamber. An exhaust gas flow line leads away from the collection chamber. On an exit-side or outlet-side end of the outer shell of the diffuser, an edge is formed which projects into or adjoins the collection chamber, namely adjoining the mouth cross section of the diffuser.

The flow is to pass preferably in an undisturbed manner from the diffuser into the collection chamber. In turbomachines known from practice, this proves to be difficult. In particular flow separations in the region of the exit-side end of the outer shell of the diffuser can occur which projects into the collection chamber or adjoins the collection chamber. This is disadvantageous.

There is therefore a need for a turbomachine with which a flow, emanating from a diffuser, can flow over into a collection chamber adjoining the diffuser in an undisturbed manner.

SUMMARY OF THE INVENTION

Starting out from this, it is an object of the present invention to create a new type of turbomachine.

According to an aspect of the invention, the exit-side end of the outer shell comprises a surface portion facing the collection chamber, which in the cross section extends in the radial direction. The surface section of the exit-side end of the outer shell facing the collection chamber and extending in the radial direction merges with a surface portion contoured circular segment-like in the cross section into a surface section of the exit-side end of the outer shell facing the diffuser.

Through the configuration of the turbomachine on the exit-side of the outer shell of the diffuser according to an aspect of the invention it can be ensured that a flow out of the diffuser can flow over into the collection chamber in an undisturbed manner. In particular, flow separations and swirls can be avoided. In this manner, flow losses can be minimized and the efficiency increased.

Preferentially, the surface portion contoured circular segment-like merges tangentially into the surface portion facing the collection chamber and/or into the surface portion facing the diffuser. Such a contouring of the outer shell of the diffuser at the exit-end is particularly preferred in order to minimize flow losses.

According to an advantageous further development, the surface portion of the exit-side end of the outer shell of the diffuser extending in the radial direction has a length L in the radial direction, for which the following is true: 0.1*X≤L≤X, wherein X is the dimension of the mouth cross section of the diffuser in the axial direction. According to a further advantageous further development, the surface portion of the exit-side end of the outer shell of the diffuser contoured circular segment-like has a radius R for which the following is true: 0.1*X≤R≤X, wherein X is the dimension of the mouth cross section of the diffuser in the axial direction. In particular when one, or preferentially both, these conditions are fulfilled, the flow can pass over from the diffuser particularly advantageously into the collection chamber to thereby minimize flow losses.

Preferentially, the turbomachine is an axial turbine, particularly preferably of a turbocharger. The invention is particularly advantageous when used on a turbomachine formed as axial turbine of a turbocharger.

Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Preferred further developments of the invention are obtained from the following. Exemplary embodiments of the invention are explained in more detail by way of the drawing without being restricted to this. There it shows:

The FIGURE is a schematized cross section by way of an extract through a turbomachine according to the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The FIGURE shows a highly schematized cross section by way of an extract, namely meridian section, of a turbomachine formed as an axial turbine 10 of an exhaust gas turbocharger, wherein an impeller 11 of the axial turbine 10 is subjected to axial inflow and axial outflow. Downstream of the turbine impeller 11, a diffuser 12 follows, which deflects the flow in the axial turbine 10 from axial to radial, wherein the diffuser 12 is limited by an inner shell 13 and an outer shell 14. Seen in the flow direction of the exhaust gas, the diffuser 12 is followed by a collection chamber 15. Exhaust gas which via the diffuser 12 enters or flows over into the collection chamber 15 can be discharged from the collection chamber 15 via an outflow line, which is not shown.

The diffuser 12 leads with a mouth cross section 16 into the collection chamber 15. As already explained, the diffuser 12, and thus the mouth cross section 16, is limited on the one hand by the inner shell 13 and on the other hand by the outer shell 14.

At the exit-side end 17 of the diffuser 12, and thus at the exit-side end 17 of the outer shell 14, the outer shell 14 has a defined contouring such that the exit-end of the outer shell 14 has a surface portion 18 facing the collection chamber, which in the cross section, namely in the meridian section of the FIGURE, extends in the radial direction, namely exclusively in the radial direction.

This surface portion 18 of the exit-side end 17 of the outer shell 14 facing the collection chamber 15 and extending exclusively in the radial direction in the meridian section merges with a surface portion 19 contoured circular segment-like in the cross section or meridian section into a surface portion 20 of the exit-side end 17 of the outer shell 14 facing the diffuser 12.

Here it is preferentially provided that the surface portion 19 of the exit-side end 17 of the outer shell 14 contoured circular segment-like merges into the surface portion 18 facing the collection chamber 15, which in the meridian section extends exclusively in the radial direction, and into the surface portion 20 facing the diffuser 12, which follows the contour of the diffuser, in each case tangentially, i.e., continuously.

The exit-side end 17 of the outer shell 14 of the diffuser 12 adjoins the collection chamber 15 or projects into the collection chamber 15 at least by a certain portion.

Seen in the meridian section, the exit-side end 17 of the outer shell 14, which limits the diffuser 12 on the outside, is characterized by two geometrical characteristic quantities, namely by a length L of the surface portion 18 extending in the radial direction and by a radius R of the surface portion 19 contoured circular segment-like.

Preferentially one, particularly preferably both, of the following conditions are true:

0.1*X≤L≤X

0.1*X≤R≤X

wherein

L is the length of the surface portion 18 extending in the radial direction,

R is the radius of the surface portion 19 contoured circular segment-like,

X is the dimension of the mouth cross section 16 of the diffuser in the axial direction.

The exit-side end 17 of the outer shell 14 of the diffuser 12 forms a bulge-like thickened portion which in the meridian section of the FIGURE has a thicker wall thickness than an adjoining portion of the outer shell 14.

With an exit-side end 17 of the outer shell 14 formed in such a manner, which limits the diffuser 12 in the region of the mouth cross section 16, a particularly advantageous and loss-free transfer of the flow from the diffuser into the collection chamber 15 adjoining the diffuser 12 can be ensured. By minimizing flow losses, the efficiency of the turbomachine can be increased.

The invention is preferentially employed in an axial turbine of a turbocharger. Although the invention in this application case is employed particularly advantageously, the invention can also be employed in other turbomachines having a diffuser and a collection chamber adjoining the diffuser, in which a flow, emanating from the diffuser in the radial direction, merges into the collection chamber adjoining or following the diffuser.

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

LIST OF REFERENCE NUMBERS

• • 10 Turbomachine
  • 11 Impeller
  • 12 Diffuser
  • 13 Inner shell
  • 14 Outer shell
  • 15 Collection chamber
  • 16 Mouth cross section
  • 17 Exit-side end
  • 18 Surface portion
  • 19 Surface portion
  • 20 Surface portion