Patent Application
20090226304
The invention relates to an adjusting shaft arrangement of a VTG turbocharger or wastegate turbocharger according to claim 1.
The term “VTG turbocharger” refers to a turbocharger having variable turbine geometry (VTG) which requires an adjusting shaft arrangement. In the wastegate turbocharger, the turbine bypass is controlled by means of a valve which is moved by the adjusting shaft.
In known adjusting shaft arrangements of VTG turbochargers, the problem of an imperfect sealing effect of the gap seal in the region between the adjusting shaft and the bush may occur depending on the exhaust-gas positive pressure applied, which may lead to exhaust-gas and smoke emissions of the turbocharger to the outside.
An improved seal by means of a piston ring arranged centrally in the bush is known from WO2004/063535 A1, such that its sealing effect is combined with the gap sealing effect.
However, this arrangement has the crucial disadvantage that the slip-on bevel, required for fitting the piston ring, in the bush bore markedly reduces the effective gap sealing length, since, in the case of a symmetrical bush geometry and fitting which is not laterally oriented, a slip-on bevel also expediently becomes necessary at the other bush end face.
It is therefore the object of the present invention to provide an adjusting shaft arrangement of a VTG or wastegate turbocharger which firstly constitutes a combination of gap seal and piston ring seal, in order to markedly reduce its exhaust-gas and smoke emissions to the outside, and secondly makes possible an improved sealing effect at the same bush length.
This object is achieved by the features of claim 1. The subclaims concern advantageous developments of the invention.
According to the invention, a static seal is provided between the adjusting shaft and the bush, said seal at least considerably reducing, if not entirely preventing, exhaust-gas and smoke emissions of the turbocharger to the outside via the bush.
The seal is preferably designed as a piston ring.
In an especially preferred embodiment, the seal is arranged in a groove of a main body of the adjusting shaft between a fixing section and a free end.
The main body is of stepped design, resulting in two cylindrical sections having different outside diameters. The inner contour of the bush surrounding the main body is likewise of complementary stepped design, thereby resulting in turn in two regions having a cylindrical inside diameter of different size. The transition between both regions can be designed as a slip-on bevel for fitting the piston ring, such that as long an effective sealing gap as possible remains at both ends. In this case, the annular space, produced by the transition, between bush and adjusting shaft can serve as a collecting volume for particles. Due to the particle accumulations in the collecting volume, an accumulation in the sealing gap, which may lead to sluggishness of the adjusting shaft, is avoided. The outside diameter of the bush need not necessarily be of stepped design. It may also be constant over the entire bush length. Stepping of the bush outside diameter has the additional advantage that laterally transposed incorrect fitting is prevented.
Further details, advantages and features of the invention follow from the description of two exemplary embodiments below with reference to the accompanying drawing, in which:
A known adjusting shaft arrangement 1 of a VTG turbocharger is shown in
The adjusting shaft arrangement 1 has an adjusting shaft 2 which comprises a fixing section 3 and a free end 8. Furthermore,
The adjusting shaft 2 is connected to a lever 4 via the fixing section 3.
Furthermore, the adjusting shaft arrangement 1 has a bush 5, which is arranged on the basic body 6 of the adjusting shaft 2.
Finally, a seal 7 is provided which is arranged in the region of the basic body 6 between the bush 5 and the adjusting shaft 2. For this purpose, the basic body 6 has an encircling groove and the seal can preferably be designed as a piston ring which is arranged in the groove 9. A seal which markedly restricts the escape of smoke emissions or exhaust gases to the outside is therefore obtained between the bush 5 and the adjusting shaft 2 or its basic body 6.
In the adjusting shaft arrangement shown in
In contrast thereto, the first embodiment, shown in
Accordingly, the bush 5 has a larger inside diameter in the region of the section 10 than in the region which surrounds the section 11 of the adjusting shaft 2.
The seal 7 is also arranged in a groove of the basic body 6 in the embodiment according to the invention. Therefore reference may be made to the description of
As
A second embodiment which is provided for a wastegate turbocharger is shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 202005008606.1 | Jun 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP06/04906 | 5/23/2006 | WO | 00 | 1/28/2009 |
