ROTOR ASSEMBLY FOR AN EXHAUST GAS TURBOCHARGER

Abstract

In a rotary assembly for an exhaust gas turbocharger, with a turbine wheel, a compressor wheel which is non-rotatably connected with the turbine wheel by means of a shaft, and an intermediate component of the rotary assembly, which is arranged on the shaft between the compressor wheel and the turbine wheel, at least one of the surfaces of the intermediate component and at least one of a third surface of the compressor wheel and a fourth surface of the shaft comprises projections which are harder than a base of the surface arranged on the opposite side with which they are engaged thereby to increase a permissible operating torque of the exhaust gas turbocharger.

Claims

1. A rotary assembly for an exhaust gas turbocharger, with a turbine wheel, a compressor wheel (5) which is non-rotatably connected with the turbine wheel by means of a shaft (3), and an intermediate component (8) of the rotary assembly, which is arranged on the shaft (3) between the compressor wheel (5) and the turbine wheel, wherein, for increasing a permissible operating torque of the exhaust gas turbocharger (2), at least one of the surfaces (10; 11) of at least one of the intermediate component (8) and a third surface (12) of the compressor wheel (5) or a fourth surface (13) of the shaft (3) comprises projections which are harder than a base of the surface (12; 13; 10; 11) arranged in axial engagement on the opposite side.

2. The rotary assembly according to claim 1, wherein the elevations are made by means of a laser.

3. The rotary assembly according to claim 1, the surface (10; 11; 12; 13) is in the form of an annular surface.

4. The rotary assembly according to claim 1, wherein the intermediate component (8) is one of an oil slinger ring and an axial bearing.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0012] The single FIGURE shows in a longitudinal section a cut-out of a rotary assembly for an exhaust gas turbocharger in the area of a compressor wheel of the rotary assembly.

DESCRIPTION OF PARTICULAR EMBODIMENTS

[0013] FIG. 1 shows, in a longitudinal section, a cut-out of a rotary assembly 1 for an exhaust gas turbocharger 2. The rotary assembly 1 comprises a shaft 3 as well as a turbine wheel (not shown in detail). The turbine wheel is at least partially to be accommodated in a compartment of a through-flow exhaust gas guide section (not shown in detail) of the exhaust gas turbocharger. The exhaust gas guide section comprises at least one supply duct (not shown in detail), via which exhaust gas of the combustion engine may be supplied to the compartment and thus flows to the turbine wheel. The turbine may be e. g. a radial turbine, wherein the exhaust gas flows to the turbine wheel at least essentially in the radial direction and impinges on it. Caused by the impingement of the exhaust gas on the turbine wheel, the turbine wheel rotates and with it the entire rotary assembly 1 about an axis of rotation 4. The turbine wheel could also be a turbine wheel of a so-called mixed-flow turbine, wherein in the case of a mixed-flow turbine, the incoming flow may impinge on the turbine wheel radially as well as semi-axially or axially.

[0014] The shaft 3 is at least mainly disposed in a bearing housing (not shown in detail) of the exhaust gas turbocharger and rotatably supported about the axis of rotation 4 relative to the bearing housing by means of a bearing device (not shown in detail). For driving the rotary assembly 1, the turbine wheel is non-rotatably connected with the shaft 3.

[0015] A compressor wheel 5 of an air guide section (not shown in detail) of the exhaust gas turbocharger is non-rotatably connected with the shaft 3, so that the compressor wheel 5 is driven via the turbine wheel by means of the shaft 3. Air to be supplied to the combustion engine may thus be compressed by means of the compressor wheel 5, so that the combustion engine may be operated particularly efficiently.

[0016] The compressor wheel 5 is non-rotatably connected with the turbine wheel by means of a force-locking and form-locking connection. Generally, the shaft 3 is formed integrally with the turbine wheel. To obtain the non-rotatable connection, the compressor wheel 5 is slipped onto the shaft 3 which has a smaller diameter in the shaft section 6 formed for accommodating the compressor wheel 5 than in the remaining area, and is clamped with the turbine wheel by means of a locking element 7, generally in the form of a nut.

[0017] Generally, at least one intermediate component 8 is arranged between the turbine wheel and the compressor wheel 5. In the illustrated exemplary embodiment, the intermediate component 8 is formed as an oil slinger ring. However, it could also be configured as an axial bearing, or the two components could be clamped between the turbine wheel and the compressor wheel, respectively.

[0018] In order to prevent lubricant leaking from the bearing section from penetrating into the air guide section, the so-called oil slinger ring 8 is provided which is arranged at a wheel rear side 9 of the compressor wheel 5. The oil slinger ring 8 is formed on the shaft 3, i. e. surrounding it, and extending coaxially with it.

[0019] During operation of the exhaust gas turbocharger, the rotary assembly 1 rotates at very high speeds, and these may result in a relative movement between the individual components of the rotary assembly 3, 5, 8, if an operating torque exceeds a clamping torque of the rotary assembly 1.

[0020] For increasing a permissible operating torque, a first surface 10 in the form of an annular surface 10 of the oil slinger ring 8 is provided with a surface structure which increases the surface roughness of the first annular surface 10 and exhibits a higher strength. In other words this means that the first annular surface 10 comprises axial projections which are harder than a base on which the projections are formed. Thus, the first annular surface 10 comprises a surface on the base of which elevations are formed which are harder than the base itself. This may be achieved in various ways, e. g. by means of a metal-cutting method. Preferably, the elevations are formed by means of a laser by laser structuring.

[0021] To further increase the permissible operating torque, additional surfaces, a second surface 11 in the form of an annular surface of the oil slinger ring 8, which is formed at the end of the slinger ring 8 facing away from the first annular surface 10, or at a third surface 12 in contact with the oil slinger ring 8 in the form of an annular surface of the compressor wheel rear side 9. Or a fourth surface 13 in contact with the second annular surface 11 in the form of an annular surface of the shaft 3 may comprise the projections. It is to be noted that the annular surface 10, 11, 12, 13 comprising the projections is arranged opposite an annular surface 12, 13, 10, 11 the base of which is softer than the projections. This makes it possible to press the projections into the base upon clamping the impeller, whereby a form-locking and force-locking connection is achieved.