The invention relates to a shaft assembly of an exhaust-gas turbocharger according to the preamble of claim 1.
A shaft assembly of said type according to the prior art has the problem of static overdeterminacy, which leads to bending stresses or constraining forces in the shaft assembly. This in turn results in an undesired reduction in the elasticity of the shaft assembly, which in turn can lead to imbalances. Furthermore, in real vehicle operation, an exhaust-gas turbocharger is subjected to high accelerations and temperatures. This leads to the occurrence of extreme forces in the screw connection of the compressor wheel, as a result of which retroactive settling can likewise occur.
As a result of said processes, the imbalance of the rotor or of the shaft assembly is in turn varied, which can cause undesired noises in the vehicle.
It is therefore an object of the present invention to provide a shaft assembly of an exhaust-gas aftertreatment system according to the preamble of claim 1, which shaft assembly permits a reduction in imbalances occurring during operation and in associated disturbing noises.
Said object is achieved by means of the features of claim 1.
Since the shaft nut has turned recesses, the expansion length of the shaft assembly is increased, which alone contributes considerably to the achievement of the aims stated in the introduction.
The subclaims relate to advantageous refinements of the invention.
In one particularly preferred embodiment, the shaft nut has a housing region which, by means of the enlargement of the outer diameter, provides an enlarged contact surface with the compressor wheel, which permits a reduced contact pressure and the realization of a greater preload force.
By means of turned recesses in the passage recess of the sealing sleeve, it is made possible for the sealing sleeve to tilt slightly about its center of gravity and to rest evenly on both sides. This yields the advantage of the largest possible contact surface in the screw connection and therefore a reduced contact pressure. As a result of the central position of the centering or of the central region between the turned recesses or the inner regions which are enlarged in terms of inner diameter, the influence of the sealing sleeve on possible imbalances remains unchanged.
It is preferable also for the compressor wheel to be designed to be axially as short as possible, that is to say that part of the compressor wheel which projects axially beyond the blade leading edges is designed to be as short as possible.
In particular if aluminum alloys are used for the material of the compressor wheel, it should be taken into consideration that the coefficient of thermal expansion of aluminum (approximately 2.33) is twice that of steel. In this way, the stress in the shaft assembly can be reduced by the shortening of the compressor wheel in relation to known compressor wheels.
The shaft, or the rotor constructed from the shaft and the turbine wheel, is provided preferably with two waisted portions which result in good flexibility of the shaft. The thermal expansion of the components in the shaft assembly can also be compensated, which allows plasticizing and therefore imbalance variation to be avoided.
The compressor wheel can nevertheless still be centered in the best possible fashion, as far as over the support regions, at its points with the least bore flaring.
Further details, advantages and features of the invention will emerge from the following description of exemplary embodiments on the basis of the appended drawing, in which:
The perspective sectional view of
Arranged in the interior of the bearing housing 4 is a shaft 5, to the turbine-side end of which is fastened a turbine wheel 2 and to the opposite end of which is fastened a compressor wheel 12 in a housing interior space 11 of the compressor housing 10. The shaft 5, which with the turbine wheel 2 and compressor wheel 12 fastened thereto forms a rotor of the exhaust-gas turbocharger, is supported in the bearing housing 4 by means of two floating sleeve bearings 6, 7 which are supplied with lubricant via two oil supply lines 8, 9 formed in the bearing housing 4.
As can be seen from the perspective illustration of
The perspective illustration of
As can be seen in detail from the sectional illustration of the sealing sleeve 14 in
The side view from
To supplement the disclosure, in addition to the above written disclosure of the invention, reference is hereby explicitly made to the diagrammatic illustration thereof in
1 Exhaust-gas Turbocharger
1A Shaft Assembly
2 Turbine wheel
3 Compressor
4 Bearing Housing
5 Shaft
6, 7 Floating Sleeve Bearing
8, 9 Oil Supply Lines
10 Compressor Housing
11 Housing Interior Space
12 Compressor Wheel
13 Compressor Spiral
14 Sealing Sleeve
15 Shaft Nut
16 Free End Region of the Shaft
17 Internal Thread
18 Turned Recess
19 Portion
20 Transition Region
21 Contact Surface
22, 23, 24 Regions
25 Sleeve Housing
26 Passage Recess
27, 28 End Regions of the Passage Recess
29 Central Region
30, 31 Transition Regions
32 Bearing Region
33, 34 Waisted Portions
35, 36 Support Regions
37 Stop Disk
38 Shaft Region
39 Turbine Housing
40 Plane of Start of Hub
41 Blade Leading Edge Plane
R Blade Root Rounding
Number | Date | Country | Kind |
---|---|---|---|
102009060056.6 | Dec 2009 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US10/60207 | 12/14/2010 | WO | 00 | 6/11/2012 |