Turbocharger

Abstract

A turbocharger, with a turbine and compressor housing connected to a bearing housing. An inflow housing of the turbine and bearing housing are connected via a fastening device mounted to a flange of the inflow housing with a first section and partially overlaps a flange of the bearing housing with a second section. Between the inflow housing and the bearing housing, flanges of a nozzle ring and of a sealing cover are clamped. Adjoining surfaces contacting one another in a region of a first, second, and/or a third contact clamping region are hardened.

Claims

1. A turbocharger, comprising: a shaft a turbine for expanding a first medium, having: a turbine housing; and a turbine rotor; a compressor for compressing a second medium utilising energy extracted in the turbine during expansion of the first medium, having: a compressor housing; and a compressor rotor that is coupled to the turbine rotor via the shaft; a bearing housing arranged between and connected to the turbine housing and the compressor housing, and in which the shaft is mounted; a fastening device configured to connect an inflow housing of the turbine housing and the bearing housing such that the fastening device is mounted to a flange of the inflow housing with a first section and overlaps a flange of the bearing housing with a second section at least in sections; and respective flanges of a nozzle ring and a sealing cover are clamped between the flange of the inflow housing and the flange of the bearing housing such that: a first contact clamping region is formed between the flange of the inflow housing and the flange of the nozzle ring; a second contact clamping region is formed between the flange of the nozzle ring and the flange of the sealing cover; and a third contact clamping region is formed between the flange of the sealing cover and the flange of the bearing housing; wherein, adjoining surfaces contacting one another in a region of the first contact clamping region, the second contact clamping region, and the region of the third contact clamping region are hardened, wherein a surface of the flange of the inflow housing in the first contact clamping region is hardened by coating; wherein a surface of the flange of the nozzle ring is hardened by nitriding; wherein a surface of the flange of the sealing cover is hardened by nitriding; wherein a surface of the flange of the bearing housing is hardened by a coating; and wherein a surface of the second section of the fastening device is hardened by nitriding.

2. The turbocharger according to claim 1, wherein the surface of the flange of the inflow housing in the first contact clamping region is hardened by a cobalt-chromium coating.

3. The turbocharger according to claim 1, wherein the surface of the flange of the nozzle ring in the first and/or the second contact clamping region is hardened by gas nitriding.

4. The turbocharger according to claim 1, wherein the surface of the flange of the sealing cover in the second and/or the second contact clamping region is hardened by salt bath nitriding.

5. The turbocharger according to claim 1, wherein the surface of the flange of the bearing housing in the third contact clamping region is hardened by a cobalt-chromium coating.

6. The turbocharger according to claim 1, wherein between the second section of the fastening device and the flange of the bearing housing a fourth contact clamping region is formed, whose adjoining surfaces contacting one another are hardened.

7. The turbocharger according to claim 6, wherein a surface of the flange of the bearing housing in the fourth contact clamping region is hardened by coating and a surface of the second section of the fastening device is hardened by nitriding.

8. The turbocharger according to claim 1, wherein a surface hardness in the region of the hardened surfaces is at least 40 HRC.

9. The turbocharger according to claim 7, wherein the fourth contact clamping region is hardened by coating with a cobalt-chromium coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a cross section through a turbocharger; and

(3) FIG. 2 is a cross section through a turbocharger in the region of an inflow housing and of a bearing housing of the turbocharger.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(4) The invention relates to a turbocharger.

(5) A turbocharger 1 comprises a turbine 2 for expanding a first medium, in particular for expanding exhaust gas of an internal combustion engine. Furthermore, the turbocharger 1 comprises a compressor 3 for compressing a second medium, in particular charge air, utilizing energy extracted in the turbine 2 during the expansion of the first medium.

(6) Here, the turbine 2 comprises a turbine housing 4 and a turbine rotor 5. The compressor 3 comprises a compressor housing 6 and a compressor rotor 7. The compressor rotor 7 is coupled to the turbine rotor 5 via a shaft 8, which is mounted in a bearing housing 9. The bearing housing 9 is positioned between the turbine housing 4 and the compressor housing 5 and is connected both to the turbine housing 4 and the compressor housing 5.

(7) The turbine housing 4 of the turbine 2 comprises an inflow housing 11 and an outflow housing 12. By way of the inflow housing 11, the first medium to be expanded in the region of the turbine 2 can be fed to the turbine rotor 5. By way of the outflow housing 12, first medium expanded in the region of the turbine rotor 5 flows away from the turbine 2.

(8) In addition to the inflow housing 11 and the outflow housing 12, the turbine housing 4 comprises an insert piece 13. The insert piece 13 runs, in particular, in the region of the inflow housing 11, namely adjacently to the turbine rotor 5 adjoining moving blades 14 of the turbine rotor 5 radially outside.

(9) The turbine housing 4, furthermore, comprises a nozzle ring 15. The nozzle ring 15 is also referred to as turbine guide apparatus.

(10) Furthermore, FIG. 1 shows a sealing cover 16 in the connecting region of inflow housing 11 and bearing housing 9. The sealing cover 16 is also referred to as a bearing housing cover or heat shield.

(11) The inflow housing 11 of the turbine 2 is connected to the bearing housing 2 via a fastening device 17 in such a manner that the fastening device 17 is mounted to a flange 18 of the inflow housing 11 with a first section 19, namely by way of multiple fasteners 20, and that the fastening device 17 overlaps a flange 26 of the bearing housing 9 with a second section 21 at least in sections. The fastening device 17 is also referred to as clamping claw. Seen in the circumferential direction, the fastening device 17 can be segmented.

(12) Each fastener 20 comprises a threaded bolt 22 screwed into the flange 18 of the inflow housing 11 and a nut 23 acting on the other end of the threaded bolt 22, wherein by tightening the nut 23 a defined preloading force can be exerted via the fastening device 17 on the inflow housing 11 and on the bearing housing 9. By way of this, corresponding flanges 24, 25 of nozzle ring 15 and sealing cover 16 are clamped between inflow housing 11 and bearing housing 9.

(13) In the above manner, multiple contact clamping regions are formed in the connecting region between the inflow housing 11 of the turbine 2 and the bearing housing 9, namely between the flange 18 of the inflow housing 11 and the flange 24 of the nozzle ring 15. A first contact clamping region 27 is formed between the flange 24 of the nozzle ring 15 and the flange 25 of the sealing cover 16, a second contact clamping region 28, a third contact clamping region between the flange 25 of the sealing cover 16 and the flange 26 of the bearing housing 9 and a fourth contact clamping region 30 between the flange 26 of the bearing housing 9 and the second section 21 of the fastening device 17.

(14) In terms of one aspect of the present invention, adjoining surfaces contacting one another in the region of the first contact clamping region 27, and/or in the region of the second contact clamping region 28, and/or in the third contact clamping region 29 are hardened.

(15) Preferentially, the adjoining surfaces contacting one another in the region of at least two contact clamping regions, particularly preferably in the region of all three contact clamping regions from the group of contact clamping regions comprising the first contact clamping region 27, the second contact clamping region 28, and the third contact clamping region 29 are hardened.

(16) In an advantageous further development of the invention it can be provided that adjoining surfaces contacting one another in the region of the fourth contact clamping region 30 are also hardened.

(17) The hardening of the adjoining surfaces is preferentially effected in such a manner that the surface hardness of the respective surfaces amounts to at least 40 HRC.

(18) In a preferred exemplary embodiment of the invention it is provided that a surface of the flange 18 of the inflow housing 11 of the turbine 2 in the first contact clamping region 27 is hardened by coating, preferentially by way of a cobalt-chromium coating, which is applied onto the flange 18 of the inflow housing 11 by spraying-on. The surface of the flange 24 of the nozzle ring 15 in the first contact clamping region 27 and in the second contact clamping region 28 is hardened by nitriding in each case, preferentially by gas nitriding. The surface of the flange 25 of the sealing cover 16 in the region of the second contact clamping region 28 and the third contact clamping region 29 is preferentially likewise hardened by nitriding, in particular by way of salt bath nitriding. The surface of the flange 26 of the bearing housing 9 in the third contact clamping region 29 is hardened by a coating, preferentially by a cobalt-chromium coating, which is applied to the flange 26 of the bearing housing 9 in the third contact clamping region 29 by spraying-on. The surface of the flange 26 of the bearing housing 9 in the fourth contact clamping region 29 is preferentially embodied likewise by such a cobalt-chromium coating, wherein the surface of the second section 21 of the fastening device 17 in the fourth contact clamping region 30 is preferentially hardened by nitriding. Although this hardening of the surfaces in the contact clamping regions is preferred, the surfaces can also be hardened by other hardening methods.

(19) With the invention, the wear of the above contact clamping regions 27, 28, 29, and 30 can be reduced. Because of this, the connection of inflow housing 11 of the turbine 2 and bearing housing 9 is altogether subject to less wear. The risk of unintentional loosening of this connection and the risk of an exhaust gas leakage into the surroundings can thus be reduced.

(20) 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.