Exhaust gas turbocharger with a rotor

Abstract

An exhaust gas turbocharger may include a bearing housing and a rotor. The rotor may have a shaft mounted in the bearing housing via two radial bearing bushes. Each radial bearing bush may have an inner surface facing the shaft. The inner surface may have a single chamfer, where the single chamfers of the two radial bearing bushes face one another, or two chamfers, where one of the two chamfers for each of the two radial bearing bushes facing one another are larger than the other of the two chamfers for each of the two radial bearing bushes facing away from one another.

Claims

1. An exhaust gas turbocharger comprising a bearing housing and a rotor having a shaft mounted in the bearing housing via two radial bearing bushes, wherein each radial bearing bush has an inner surface facing the shaft, the inner surface having at least (i) a single chamfer, wherein the single chamfers of the two radial bearing bushes face one another, and (ii) two chamfers, wherein one of the two chamfers for each of the two radial bearing bushes facing one another are larger than the other of the two chamfers for each of the two radial bearing bushes facing away from one another.

2. The exhaust gas turbocharger according to claim 1, wherein at least one radial bearing bush is fixed in an axial direction by at least one fixing element.

3. The exhaust gas turbocharger according to claim 2, wherein the at least one fixing element is formed as at least one of a circlip, a radial step of the rotor, and a thrust washer.

4. The exhaust gas turbocharger according to claim 2, wherein the fixing element includes a chamfer favoring an oil discharge out of an annular gap located between the radial bearing bushes and the shaft.

5. The exhaust gas turbocharger according to claim 1, wherein each radial bearing bush has at least one oil feed bore, which radially penetrates the respective radial bearing bush.

6. The exhaust gas turbocharger according to claim 5, wherein the at least one oil feed bore is centered with respect to the inner surface of the respective radial bearing bush and off center with respect to an outer surface of the respective radial bearing bush.

7. The exhaust gas turbocharger according to claim 5, wherein at least one radial bearing bush is fixed in an axial direction by at least one fixing element.

8. The exhaust gas turbocharger according to claim 7, wherein the at least one fixing element includes at least one chamfer favoring an oil discharge out of an annular gap located between the radial bearing bushes and the shaft.

9. A radial bearing bush for an exhaust gas turbocharger having a rotor with a shaft, the radial bearing bush comprising an outer surface and an inner surface facing the shaft, the inner surface having one of a single chamfer or two chamfers, which are different in size.

10. The radial bearing bush according to claim 9, further comprising at least one oil feed bore penetrating the radial bearing bush from the outer surface to the inner surface.

11. The radial bearing bush according to claim 10, wherein the at least one oil feed bore is centered with respect to the inner surface and off center with respect to the outer surface.

12. An exhaust gas turbocharger comprising a bearing housing and a rotor having a shaft mounted in the bearing housing via two radial bearing bushes, wherein each radial bearing bush has an inner surface facing the shaft, each inner surface of the respective radial bearing bush having a first chamfer facing the first chamfer of the other radial bearing bush, and wherein at least one radial bearing bush is fixed in an axial direction by at least one fixing element that includes at least one chamfer favoring an oil discharge out of an annular gap located between the radial bearing bushes and the shaft.

13. The exhaust gas turbocharger according to claim 12, wherein each radial bearing bush has a second chamfer facing away from the second chamfer of the other radial bearing bush, the first chamfer being larger than the second chamfer of the respective radial bearing bush.

14. The exhaust gas turbocharger according to claim 13, wherein each radial bearing bush has at least one oil feed bore, which radially penetrates the respective radial bearing bush.

15. The exhaust gas turbocharger according to claim 14, wherein the at least one oil feed bore is centered with respect to the inner surface of the respective radial bearing bush and off center with respect to an outer surface of the respective radial bearing bush.

16. The exhaust gas turbocharger according to claim 12, wherein each radial bearing bush has at least one oil feed bore, which radially penetrates the respective radial bearing bush.

17. The exhaust gas turbocharger according to claim 16, wherein the at least one oil feed bore is centered with respect to the inner surface of the respective radial bearing bush and off center with respect to an outer surface of the respective radial bearing bush.

18. The exhaust gas turbocharger according to claim 12, wherein the fixing element is formed as at least one of a circlip, a radial step of the rotor, or a thrust washer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There it shows, in each case schematically,

(2) FIG. 1 an exhaust gas turbocharger with a rotor, the shaft of which is mounted in the bearing housing via two radial bearing bushes according to the prior art,

(3) FIG. 2 a representation as in FIG. 1, however with radial bearing bushes having merely a single chamfer according to the invention,

(4) FIG. 3 a representation as in FIG. 1, however with radial bearing bushes having two different size chamfers according to the invention,

(5) FIG. 4 a representation as in FIG. 2, however with an additional fixing element.

DETAILED DESCRIPTION

(6) According to FIG. 1, an exhaust gas turbocharger 1 according to the prior art comprises a rotor 2, the shaft 3 of which is mounted in a bearing housing 6 via two radial bearing bushes 4 and 5. The two radial bearing bushes 4, 5 each have two chamfers 8 and 9 on their inner surface 7 facing the shaft 3, wherein the chamfers 8, 9 are formed identical in size. This produces a central axial spacing L.sub.0 of the two inner surfaces 7.

(7) According to FIGS. 2 to 4, an exhaust gas turbocharger 1 according to the invention likewise comprises a rotor 2, the shaft 3 of which is mounted in the bearing housing 6 via two radial bearing bushes 4, 5. In contrast with FIG. 1, the reference numbers are written without apostrophe in this case. Looking at FIG. 2 it is now evident that each of the two radial bearing bushes 4, 5 according to the invention merely has a single chamfer 9 on its inner surface 7 facing the shaft 3, which face one another in the installed state. The chamfer 8 located outside which is provided according to the prior art is not provided with the radial bearing bushes 4, 5 according to FIG. 2. This produces a central axial spacing L.sub.1 of the two inner surfaces 7, which is clearly larger than the axial spacing L.sub.0 in the case of the exhaust gas turbocharger 1 according to the prior art, so that the rotor 2 with the exhaust gas turbocharger 1 according to the invention according to FIG. 2 has a wider mounting and because of this the risk of a wobbling movement of the rotor 2 can be reduced.

(8) Alternatively to the embodiments of the radial bushes 4, 5 or of the exhaust gas turbocharger 1 according to the invention shown according to FIG. 2, the two radial bearing bushes 4, 5 according to FIG. 3 have two chamfers 8, 9 on their inner surface 7 facing the shaft 3, wherein the chamfers 9 facing one another in the installed state are larger than the chamfers 8 facing away from one another in the installed state. This results in a central axial spacing L.sub.2 of the two inner surfaces 7 of the radial bearing bushes 4, 5 which is larger than the central axial spacing L.sub.0 in the case of the exhaust gas turbocharger 1 according to the prior art, but smaller than the central axial spacing L.sub.1 in the case of the exhaust gas turbocharger 1 according to the invention according to FIG. 2. The central axial spacing L in this case always relates to the axial centre line of the respective inner surface 7 of the radial bearing bush 4, 5.

(9) Looking at FIGS. 2 to 3 it is evident that each radial bearing bush 4, 5 comprises an oil feed bore 10, which radially penetrates the radial bearing bush 4, 5 and conducts oil into an annular space located between the shaft 3 and the inner surface 7 of the respective radial bearing bush 4, 5 for establishing a lubricating film. The oil feed bore 10 in this case is preferentially arranged in the centre with respect to the inner surface 7 thus not in the centre with respect to the outer surface 11 of the respective radial bearing bush 4, 5.

(10) Looking at the exhaust gas turbocharger 1 according to FIG. 4, it is evident that the radial bearing bush 4, 5 are each fixed by a fixing element 12 in axial direction 13. The fixing element 12 can for example be designed as a circlip, as a radial step 14 of the rotor 2 or of the shaft 3 or as a thrust washer 15. At any rate, it limits an axial freedom of movement of the respective radial bearing bush 4, 5. On the fixing element 12, a chamfer 16 can be additionally provided which favours oil discharge out of an annular gap located between the radial bearing bush 4, 5 and the shaft 3 and because of this also leads to the establishment of a bearing lubricating oil film between the fixing element 12 and the face end of the respective radial bearing bush 4, 5.

(11) Obviously, not only the exhaust gas turbocharger 1 as a whole is to be protected with the present application but also the radial bearing bush 4, 5, which can for example be offered as replacement part.

(12) The radial bearing bushes 4, 5 and the exhaust gas turbocharger 1 according to the invention make possible a larger central axial spacing L of the two radial bearing bushes 4, 5 and the associated inner surfaces 7, as a result of which in particular a wobbling tendency of the rotor 2 can be reduced.