Turbine housing for a turbocharger of an internal combustion engine, and turbocharger

Abstract

A turbine housing for a turbocharger of an internal combustion engine includes an annular duct for conducting an exhaust-gas mass flow to a turbine wheel to be disposed in the turbine housing and an exhaust-gas discharge duct for discharging the exhaust-gas mass flow from the turbine housing after impinging on the turbine wheel. An insulating element is respectively disposed in a region of an inner wall of the annular duct and in a region of an inner wall of the exhaust-gas discharge duct. A turbocharger having the turbine housing is also provided.

Claims

1. A turbine housing for a turbocharger of an internal combustion engine, the turbine housing comprising: a turbine wheel disposed in the turbine housing; an annular duct for conducting an exhaust-gas mass flow to said turbine wheel, said annular duct having an inner wall; an exhaust-gas discharge duct for discharging the exhaust-gas mass flow from the turbine housing after impinging on said turbine wheel, said exhaust-gas discharge duct having an inner wall; insulating elements, a first one of said insulating elements being disposed within said annular duct over a region of said inner wall of said annular duct and a second one of said insulating elements being disposed within said exhaust-gas discharge duct over a region of said inner wall of said exhaust-gas discharge duct; and a longitudinal axis and a sealing contour, said sealing contour being free of any insulating element between said exhaust-gas discharge duct and said annular duct relative to said longitudinal axis.

2. The turbine housing according to claim 1, which further comprises a wastegate valve seat, a bearing-housing connection flange and an exhaust-gas connection flange, the turbine housing being free of any insulating element in a region of at least one of said wastegate valve seat, said bearing-housing connection flange or said exhaust-gas connection flange.

3. The turbine housing according to claim 1, wherein at least one of said insulating elements is a layer applied at least partially to at least one of said inner wall of said annular duct or said inner wall of said exhaust-gas discharge duct.

4. The turbine housing according to claim 1, wherein at least one of said insulating elements is an inlay element inserted or at least partially molded in or at least partially encapsulated into the turbine housing.

5. The turbine housing according to claim 4, wherein said at least one insulating element is a multilayer element including a first layer facing an exhaust-gas mass flow during operation and exhibiting a material resistant to high temperatures, and a second insulating layer following said first layer.

6. The turbine housing according to claim 5, wherein said at least one insulating element includes a third layer following said second layer and facing at least one of said inner wall of said annular duct or said inner wall of said exhaust-gas discharge duct.

7. The turbine housing according to claim 6, wherein said third layer is firmly connected to the turbine housing.

8. The turbine housing according to claim 1, wherein at least one of said insulating elements includes a metal foam.

9. The turbine housing according to claim 1, which further comprises a sealing contour, a bearing-housing connection flange, an exhaust-gas connection flange, and local cooling in a region of at least one of said sealing contour, said bearing-housing connection flange or said exhaust-gas connection flange.

10. The turbine housing according to claim 1, which further comprises a wastegate valve seat and local cooling in a region of said wastegate valve seat.

11. The turbine housing according to claim 6, wherein, said first layer is a metal layer, said second layer is an insulating material layer, and said third layer is a metal layer.

12. The turbine housing according to claim 1, wherein said insulating elements are spaced apart from one another with respect to an exhaust-gas flow direction of the turbine housing.

13. A turbocharger for an internal combustion engine, the turbocharger comprising: a bearing housing; a rotor shaft rotatably mounted in said bearing housing; a turbine housing according to claim 1 being mechanically secured to said bearing housing; and said turbine wheel disposed for conjoint rotation on said rotor shaft.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a schematic sectional view of a turbocharger,

(2) FIG. 2 shows a schematic partial sectional view of a turbocharger according to an exemplary embodiment of the invention, and

(3) FIG. 3 shows a schematic illustration of a wastegate valve seat of the turbocharger according to the exemplary embodiment of the invention.

DESCRIPTION OF THE INVENTION

(4) FIG. 1 schematically shows a sectional illustration of an example of an exhaust-gas turbocharger 1, which comprises an exhaust-gas turbine 20, a fresh-air compressor 30 and a rotor bearing 40. The exhaust-gas turbine 20 is equipped with a wastegate valve 29 and an exhaust-gas mass flow AM is indicated by arrows. The fresh-air compressor 30 has an overrun air recirculation valve 39 and a fresh-air mass flow FM is likewise indicated by arrows. A turbocharger rotor 10, as it is known, of the exhaust-gas turbocharger 1 has a turbine rotor 12 (also referred to as turbine wheel), a compressor rotor 13 (also referred to as compressor wheel) and a rotor shaft 14 (also referred to as shaft). The turbocharger rotor 10 rotates about a rotor axis of rotation 15 of the rotor shaft 14 during operation. The rotor axis of rotation 15 and at the same time the turbocharger axis 2 (also referred to as longitudinal axis) are illustrated by the indicated centerline and identify the axial orientation of the exhaust-gas turbocharger 1. The turbocharger rotor 10 is supported with its rotor shaft 14 by means of two radial bearings 42 and one axial bearing washer 43. Both the radial bearings 42 and the axial bearing washer 43 are supplied with lubricant via oil supply ducts 44 of an oil connection 45.

(5) As a rule, a conventional exhaust-gas turbocharger 1, as illustrated in FIG. 1, has a multipart construction. Here, a turbine housing 21 that is arrangeable in the exhaust tract of the internal combustion engine, a compressor housing 31 that is arrangeable in the intake tract of the internal combustion engine, and, between the turbine housing 21 and compressor housing 31, a bearing housing 41 are arranged alongside one another with respect to the common turbocharger axis 2 and connected together in terms of assembly.

(6) A further structural unit of the exhaust-gas turbocharger 1 is represented by the turbocharger rotor 10, which has the rotor shaft 14, the turbine rotor 12, arranged in the turbine housing 21, having rotor blading 121, and the compressor rotor 13, arranged in the compressor housing 31, having rotor blading 131. The turbine rotor 12 and the compressor rotor 13 are arranged on the opposite ends of the common rotor shaft 14 and connected for conjoint rotation thereto. The rotor shaft 14 extends in the direction of the turbocharger axis 2 axially through the bearing housing 41 and is provided therein with rotary support in the axial and radial directions about its longitudinal axis, the rotor axis of rotation 15, wherein the rotor axis of rotation 15 lies on the turbocharger axis 2, i.e. coincides therewith.

(7) The turbine housing 21 has one or more exhaust-gas annular ducts, referred to as exhaust-gas channels 22 or spiral paths, that are arranged annularly around the turbocharger axis 2 and the turbine rotor 12 and narrow helically toward the turbine rotor 12. These annular ducts 22 each have their own or a common exhaust-gas feed duct 23, directed tangentially outward, with a manifold connection branch 24 for connecting to an exhaust-gas manifold (not illustrated) of an internal combustion engine, through which the exhaust-gas mass flow AM flows into the particular exhaust-gas channel 22. The exhaust-gas channels 22 furthermore each have a slit-type opening extending at least over a part of the inner circumference, referred to as the exhaust-gas inlet slit 25, which extends at least partly in a radial direction toward the turbine rotor 12 and through which the exhaust gas mass flow AM flows onto the turbine rotor 12.

(8) The turbine housing 21 furthermore has an exhaust-gas discharge duct 26, which extends away from the axial end of the turbine rotor 12 in the direction of the turbocharger axis 2 and has an exhaust-gas connection flange 27 (also exhaust connection branch) for connecting to the exhaust system (not illustrated) of the internal combustion engine. Via this exhaust-gas discharge duct 26, the exhaust-gas mass flow AM emerging from the turbine rotor 12 is discharged into the exhaust system of the internal combustion engine.

(9) Over a particular region, between the exhaust-gas inlet slit 25 and exhaust-gas discharge duct 26, the radial inner contour of the turbine housing 21 follows the outer contour of the turbine rotor 12 accommodated therein. This region of the inner contour of the turbine housing 21 is denoted turbine sealing contour 28 and has the effect that the exhaust-gas mass flow AM flows as completely as possible through, and not past, the rotor blading 121 of the turbine rotor 12. In this respect, it is necessary for as small a gap as possible to be ensured between the sealing contour 28 of the turbine housing 21 and the outer contour of the turbine rotor 12 during operation, this allowing free rotation of the turbine rotor 12 but limiting flow-around losses to a minimum.

(10) The wastegate valve 29 is a corresponding bypass-valve device on the turbine side. The wastegate valve 29 connects the exhaust-gas feed duct 23, upstream of the turbine rotor 12 in the direction of flow of the exhaust-gas mass flow AM, to the exhaust-gas discharge duct 26, downstream of the turbine rotor 12 in the direction of flow of the exhaust-gas mass flow AM, via a wastegate duct 291 in the turbine housing 21. The wastegate valve 29 can be opened or closed via a closing device, for example a wastegate flap 292.

(11) Further details of the turbocharger 1 are not explained more specifically.

(12) FIG. 2 shows a cross-sectional partial view of a turbocharger 1 according to an embodiment of the invention, on the basis of which the configuration of the turbine housing 21 is described in more detail. The turbine housing 21 is distinguished by selective cooling and thermal insulation. It should be noted that details of the turbocharger 1 illustrated in FIG. 1 differ from the turbocharger 1 explained on the basis of FIG. 1.

(13) The turbine housing 21 is produced from a light metal material such as gray cast iron, although other materials are also conceivable.

(14) According to FIG. 2, an inner wall 221 of the annular duct 22 is provided with a first insulating element 211. The insulating element 211 is matched to the shaping of the inner wall 221 of the annular duct 22, and at least partially lines the latter. The insulating element 211 is an inlay part, which has three layers 212 to 214. The first layer 212 faces the exhaust-gas mass flow AM during operation and represents an inner skin of the insulating element 211. The first layer 212 is produced from a metal material, for example a metal material that is resistant to high temperatures, for example as a metal sheet. The second layer 213 is in the form of an insulating layer and exhibits insulating material, for example ceramic. The third layer 214 faces the turbine housing 21, i.e. the inner wall 221. The third layer 214 can likewise consist of a metal material that is resistant to high temperatures. The first insulating element 211 is molded into the turbine housing 21. For example, only the third layer 214 is molded in. Alternatively, two or all of the layers 212 to 214 are molded in.

(15) In a similar manner to the first insulating element 211, a second insulating element 215 is provided, which is arranged in the region of the exhaust-gas discharge duct 26 on an inner wall 222 of the turbine housing 21. It has the same layers 212 to 214 and is in the form of an inlay part. The second insulating element 215 is likewise molded into the turbine housing 21.

(16) As is apparent from FIG. 2, the sealing contour 28 of the turbine housing 21 is free of any insulating element. Furthermore, in the region of a bearing-housing connection flange 217 and of the exhaust-gas connection flange 14, no further thermal insulation is provided, since there are high tolerance demands in this region, as described at the beginning. Furthermore, the region of the wastegate valve 29, in particular the wastegate duct 291, is also not provided with any insulation.

(17) In order to ensure sufficient cooling of the turbine housing 21, local cooling is provided in the abovementioned regions. This is water cooling, wherein cooling ducts 216 have been introduced into the turbine housing 21, water flowing as cooling medium through said cooling ducts 216 during operation, in order to absorb thermal energy.

(18) Thus, in the regions which have been machined and on which high tolerance demands are placed, no insulating elements are provided, but rather local cooling.

(19) As is apparent from FIGS. 2 and 3, local cooling is provided at a wastegate valve seat 293 of the wastegate valve 29. In this case, the cooling is internal water cooling 294 of the wastegate valve seat 293, which extends in a duct-like manner around the wastegate valve seat 293, such that water as cooling medium can absorb thermal energy. The water cooling 294 has a water inflow 295 and a water return flow 296. This is illustrated schematically in FIG. 3.

(20) The described turbocharger 1 is distinguished by the combination of selective insulation and water cooling of the turbine housing 21. As mentioned at the beginning, the mentioned advantages and functions can be achieved as a result. In particular a less thermally resistant material, for example a light metal material, can be used for the turbine housing 21, this having considerable price advantages compared with cast materials that are resistant to height temperatures. The combination of selective cooling and insulation results in increased turbine efficiency and thus an overall efficiency of the turbocharger 1 than for example in the case of peripherally cooled, for instance water-cooled, turbine housings. Furthermore, the component temperatures of the turbine housing 21 can be lowered to a required level. As a result of the provision of local cooling in the region of the bearing-housing connection flange 217, it is also possible for local cooling integrated into the bearing housing 41 to be dispensed with, since the latter is simultaneously cooled via the turbine housing 21.

(21) The insulating elements 211 and 215 are alternatively configured in some other way. For example, one or both insulating elements 211 and 215 exhibit(s) a metal foam, for example as second layer 213. In a further alternative, one or both insulating elements 211 and 215 is/are not molded into the turbine housing 21, but merely inserted. In this case, an insulating element 211 and/or 215 can be fixed mechanically during the assembly of the turbocharger 1, for example clamped. Furthermore, it is also conceivable for one or both insulating elements 211 and 215 to be applied as a coating to the corresponding inner walls of the turbine housing 21.

(22) It should be noted that the turbocharger 1 described on the basis of FIGS. 2 and 3 can be configured as per the turbocharger explained schematically on the basis of FIG. 1. This is not absolutely necessary, however. The turbocharger 1 according to FIGS. 2 and 3 can have alternative configurations.