EXHAUST GAS TURBOCHARGER FOR A MOTOR VEHICLE
The invention relates to an exhaust gas turbocharger (1) for a motor vehicle with a shaft (2) carrying a compressor wheel and a turbine wheel which is mounted in a bearing housing (3), wherein in the region of the mounting in the bearing housing (3) at least one shaft sealing ring (4) is provided which is held in a shaft-sided circumferential groove (5). It is substantial to the invention here that at least two axially adjacent shaft sealing rings (4, 4′) are provided which are held in corresponding shaft-sided circumferential grooves (5, 5′), that an outer diameter (D) of the shaft (2) surrounding the shaft-sided circumferential grooves (5, 5′) is different in size.
The present invention relates to an exhaust gas turbocharger for a motor vehicle with a shaft carrying a compressor wheel and a turbine wheel according to the preamble of Claim 1.
Exhaust gas turbochargers are usually operated with a high rotational speed which as a rule requires hydrodynamic oil lubrication of the axial and radial bearings. Since with exhaust gas turbochargers a rotor is in contact with various media, namely with cold fresh air on a compressor side, an engine oil in the bearing region and a hot exhaust gas flow on a turbine side, effective sealing in the region of the rotating rotor, that is in the region of the shaft, to the neighbouring static components is indispensable. Here, the use of shaft sealing rings has established itself, which shaft sealing rings more preferably with a narrower design of the shaft sealing ring compared to a groove width, enforce a diversion of a media flow around the shaft sealing ring preloaded on the bearing housing. Since an axial gap between the shaft sealing ring and a circumferential groove turned into the shaft, that is into the rotor, is generally embodied very narrow, a major reduction of an oil leakage into the turbine or compressor housing and a severe reduction of an exhaust gas or a fresh air flow in the bearing housing (so-called blow-by) occurs. If in addition a plurality of shaft sealing rings are employed axially adjacent to one another the length of the gap is extended accordingly, as a result of which the sealing effect can be additionally intensified. Through ever increasing requirements in terms of emission reduction two and more shaft sealing rings are therefore increasingly employed both on a turbine as well as a compressor side. However, the assembly of the individual shaft sealing rings is often problematic because of a usually constant shaft diameter and time and again results in defectively assembled shaft sealing rings, which are not immediately discovered upon delivery to the customer and can then result in subsequent failures of the exhaust gas turbocharger.
The present invention therefore deals with the problem of stating an improved or at least an alternative embodiment for an exhaust gas turbocharger of the generic type which more preferably is characterized by simplified assembly.
According to the invention this problem is solved through the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.
The present invention is based on the general idea of designing an outer diameter of a rotor in an exhaust gas turbocharger, that is an outer diameter of a shaft carrying a turbine wheel and a compressor wheel adjacent to shaft-sided circumferential grooves, in which shaft sealing rings are held, differently in size, as a result of which on the one hand the assembly of the shaft sealing rings, more preferably with an outer diameter increasing in assembly direction of the shaft sealing rings can be facilitated and on the other hand a clearly improved sealing effect can be achieved. Here, the shaft carries a compressor wheel on the compressor side in the known manner and a turbine wheel on the turbine side and is mounted in the bearing housing of the exhaust gas turbocharger, wherein according to the invention at least two shaft sealing rings axially adjacent to each other are provided which are held in respective shaft-sided circumferential grooves. These at least two shaft sealing rings axially adjacent to each other can be provided on the turbine and/or compressor side, wherein at the same time an outer diameter of the shaft surrounding the shaft-sided circumferential grooves can be different in size so that more preferably a respective radial depth of two groove flanks belonging to a circumferential groove can be different in magnitude. The establishment of different size outer diameters in the region of the circumferential grooves according to the invention can be simply realised in terms of production through appropriate turning tools so that simplified assembly and increased tightness on the one hand can be achieved easily in terms of production and on the other hand cost-effectively.
This solution can be applied on the turbine side and/or the compressor side. With an advantageous further development of the solution according to the invention the outer diameter of the shaft increases in assembly direction of the shaft sealing rings in the region of the circumferential grooves in a sawtooth-like manner. Such an embodiment more preferably offers a major advantage when a pressure from the turbine side is higher than an oil pressure in the bearing housing, wherein through the sawtooth-like embodiment of the outer diameter of the shaft, a blow-by gas flow from the turbine side can be clearly reduced.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the respective figure description by means of the drawings.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combinations stated but also in other combinations or by themselves, without leaving the context of the present invention.
Preferred exemplary embodiment of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference characters refer to same or similar or functionally same components.
Here it shows, in each case schematically,
According to
Looking at
Through the shaft tapering against the assembly direction 6, clearly simplified assembly of the shaft sealing rings 4, 4′ can be achieved so that the exhaust gas turbocharger 1 according to the invention is easier to assemble and more preferably producible with less scrap. Preferentially the outer diameter D of the shaft 2 tapers towards a bearing side. Through the different overlap lengths U between the shaft sealing rings 4, 4′ and the circumferential grooves 5, 5′ an overall sealing section consisting of the individual overlap lengths U1, U2, U3 and U4 can be increased wherein according to the case shown in
According to
According to
With the configuration of the shaft 2 according to the invention the assembly of the shaft sealing rings 4, 4′ can more preferably be facilitated since it is easier to pass the shaft sealing ring 4′ over the groove 5 of the shaft sealing ring 4, which with constant outer diameter D in the past usually caused problems and time and again resulted in defectively installed shaft sealing rings 4, 4′. At the same time, a labyrinth length, determined from the sums of the overlap lengths U1-U4, can be extended and thus the sealing effect increased as a result.
From
According to
In both detail views “X” and “Y” it is clearly visible that the bearing bush 8 has two chamfers 10, 10′ which facilitate assembly. The circumferential grooves 5, 5′ with the exhaust gas turbocharger according to
Claims
1.-7. (canceled)
8. An exhaust gas turbocharger comprising:
- a shaft carrying at least on of a compressor wheel and a turbine wheel, wherein the shaft is mounted in a bearing housing, wherein at least one shaft sealing ring is provided and is retained in a shaft-sided circumferential groove, wherein at least two shaft sealing rings are positioned axially adjacent to each other and are retained in the corresponding shaft-sided circumferential grooves; and
- an outer diameter (D) of the shaft surrounding the shaft-sided circumferential grooves is a different in size.
9. The exhaust gas turbocharger according to claim 1, wherein the shaft outer diameter (D) increases steadily in an assembly direction of the shaft sealing rings.
10. The exhaust gas turbocharger according to claim 1, wherein the shaft outer diameter (D) increases unsteadily in an assembly direction of the shaft sealing rings.
11. The exhaust gas turbocharger according to claim 1, wherein the shaft outer diameter (D) increases step-like in an assembly direction of the shaft sealing rings.
12. The exhaust gas turbocharger according to claim 1, wherein the shaft outer diameter (D) increases sawtooth-like in an assembly direction of the shaft sealing rings.
13. The exhaust gas turbocharger according to claim 1, wherein a transition from a groove wall to a groove base is rounded.
14. The exhaust gas turbocharger according to claim 1, wherein at least one shaft sealing ring is provided on at least one of the compressor side and the turbine side.
15. The exhaust gas turbocharger according to claim 1, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
16. The exhaust gas turbocharger according to claim 2, wherein a transition from a groove wall to a groove base is rounded.
17. The exhaust gas turbocharger according to claim 2, wherein at least one shaft sealing ring is provided on at least one of the compressor side and the turbine side.
18. The exhaust gas turbocharger according to claim 2, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
19. The exhaust gas turbocharger according to claim 3, wherein a transition from a groove wall to a groove base is rounded.
20. The exhaust gas turbocharger according to claim 3, wherein at least one shaft sealing ring is provided on at least one of the compressor side and the turbine side.
21. The exhaust gas turbocharger according to claim 3, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
22. The exhaust gas turbocharger according to claim 4, wherein a transition from a groove wall to a groove base is rounded.
23. The exhaust gas turbocharger according to claim 4, wherein at least one shaft sealing ring is provided on at least one of the compressor side and the turbine side.
24. The exhaust gas turbocharger according to claim 4, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
25. The exhaust gas turbocharger according to claim 5, wherein at least one shaft sealing ring is provided on at least one of the compressor side and the turbine side.
26. The exhaust gas turbocharger according to claim 5, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
27. The exhaust gas turbocharger according to claim 6, wherein the circumferential grooves are arranged at least one of directly on the shaft and on a ring element joined with the shaft in a rotationally fixed manner.
Type: Application
Filed: Oct 30, 2009
Publication Date: May 6, 2010
Inventors: Thomas Berger (Ditzingen), Aurelia Kraemer (Ludwigsburg), Michael Just (Ludwigshafen), Senol Soeguet (Stuttgart)
Application Number: 12/609,722