Bearing device for a shaft, in particular of a turbocharger device

Abstract

A bearing device for a shaft has at least two axially spaced-apart, radial anti-friction bearings with rolling bodies. In each of the anti-friction bearings, an inner race is formed for the rolling bodies on an inner bearing element which is connected fixedly to the shaft. An outer race is formed for the rolling bodies on an outer bearing sleeve having at least two bearing sleeve elements which are guided coaxially with respect to one another in a guide device. Each of the anti-friction bearings is assigned a separate bearing sleeve element with in each case one anti-friction bearing running surface. The guide device converts a rotation of at least one of the bearing sleeve elements about the shaft longitudinal axis into a spacing change of the two bearing sleeve elements. The axial spacing between the bearing sleeve elements can be adjusted and/or fixed and/or prestressed with spring element.

Claims

1. A bearing device for a shaft, comprising: at least two rolling bearings spaced apart in an axial direction and having rolling elements; an inner bearing element fixedly connected to, or integrally formed with, the shaft; an outer bearing sleeve formed with at least two bearing sleeve elements; each of said rolling bearings having an inner running surface for said rolling elements formed on said inner bearing element and having an outer running surface formed on said outer bearing sleeve; each of said rolling bearings being assigned a separate bearing sleeve element each formed with one outer running surface for said rolling elements; said at least two bearing sleeve elements being disposed coaxially with respect to one another and said two bearing sleeve elements having mutually facing oblique end faces disposed to slide on one another upon being rotated relative to one another for converting a rotation of at least one of said bearing sleeve elements about a longitudinal axis of the shaft into a change in a spacing between said two bearing sleeve elements; and wherein said two bearing sleeve elements are preloaded by a spring element and said spring element is resiliently compressible and/or expandable substantially in a circumferential direction of said two bearing sleeve elements and said spring element braces said two bearing sleeve elements relative to one another in the circumferential direction.

2. The bearing device according to claim 1, wherein said two bearing sleeve elements are shaped to enable said two bearing sleeve elements to be moved relative to one another relative to a third shaped element, in a combined coaxial rotary movement and an axial translational movement, at least in a partial range of a movement thereof.

3. The bearing device according to claim 2, wherein the suitable shaping is a bayonet joint.

4. The bearing device according to claim 1, wherein said spring element is at least one wire spring.

5. The bearing device according to claim 1, wherein said spring element is at least one wire spring having a first end connected to a first of said bearing sleeve elements and a second end connected to a second of said bearing sleeve elements.

6. The bearing device according to claim 1, wherein said spring element is at least one wire spring formed as a circular ring segment, said ring segment having ends with fixing elements formed to engage on an outer contour of one of said two bearing sleeve elements in each case.

7. The bearing device according to claim 6, wherein said fixing elements are the ends of said ring segment bent radially inward.

8. The bearing device according to claim 1, configured as a bearing for a shaft of a turbocharger device of an internal combustion engine.

9. A method for producing a bearing device according to claim 1, the method comprising: mounting rolling elements of a first radial rolling bearing on an inner bearing element on the shaft; subsequently mounting an outer bearing sleeve to cause one bearing sleeve element to be in engagement with the rolling elements; subsequently mounting the rolling elements of the second radial rolling bearing in an axially shortened state of the outer bearing sleeve; and subsequently pulling the first and second bearing sleeve elements apart axially by rotating the sleeve elements relative to one another about a longitudinal axis of the shaft, and subsequently bracing the first and second bearing sleeve elements relative to one another in a circumferential direction by using a spring element which is resiliently compressible and/or expandable substantially in a circumferential direction of said two bearing sleeve elements.

10. The method according to claim 9, which comprises connecting the first and second bearing sleeve elements to one another with the spring element.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention is shown and then described below with reference to an illustrative embodiment in figures of a drawing, in which:

(2) FIG. 1 shows part of the turbocharger device having a shaft and a bearing device in a longitudinal section,

(3) FIG. 2 shows a shaft with two inner bearing elements and two unmounted sets of rolling elements and corresponding bearing sleeve elements in a longitudinal section,

(4) FIG. 3 shows an assembly similar to that shown in FIG. 2, wherein a first set of rolling elements is arranged on an inner bearing element on the shaft,

(5) FIG. 4 shows an assembly like that in FIGS. 2 and 3, wherein, in addition, bearing sleeve elements at a shorter axial distance from one another than in the final state have been mounted,

(6) FIG. 5 shows an assembly like that in FIG. 4, wherein, in addition, a second set of rolling elements has been mounted,

(7) FIG. 6 shows an assembly like that in FIG. 5, wherein two separate elements of the bearing device, each having one bearing sleeve element, have been moved axially relative to one another in such a way that the two rolling bearings are adjusted axially relative to one another,

(8) FIG. 7 shows a three-dimensional view of a shaft having a bearing device according to the invention without a spring element,

(9) FIG. 8 shows an assembly like that in FIG. 7, wherein, in addition, the spring elements are shown, and

(10) FIG. 9 shows a side view of a shaft having a bearing device, wherein a mounted spring element can also be seen.

DESCRIPTION OF THE INVENTION

(11) FIG. 1 shows parts of a turbocharger device of an internal combustion engine in a longitudinal section, wherein the right-hand side shows a turbine wheel 1, which is secured on a rotatably mounted shaft 2. The turbine wheel 1 is located in an exhaust gas flow of an internal combustion engine and is driven by said flow.

(12) The shaft 2 is supported radially in a bearing assembly 3 and, in this arrangement, passes through a housing 4, in which lubricating devices for the bearing device 3 are provided, for example. A compressor impeller (not shown in the drawing), which compresses the intake air in the intake flow of the internal combustion engine, is provided on the opposite side of the housing 4 from the turbine wheel 1.

(13) During operation of the turbocharger device, the bearing device 3 is exposed to large temperature fluctuations, wherein, in particular, large temperature differences can occur between the exhaust gas side and the compressor side.

(14) FIG. 2 shows the shaft 2 with various offsets, wherein inner bearing elements 5, 6 in the form of axial segments of the shaft 2 are provided at two points, wherein a running surface/raceway for the rolling elements of a rolling bearing is provided in each of the inner bearing elements 5, 6. In cross section, therefore, a groove-type recess can be seen, which in each case runs around in the circumferential direction of the shaft 2.

(15) The left-hand side of FIG. 2 shows a cage 7 with rolling elements 8, 9 in the form of balls as well as two bearing sleeve elements 10, 11 and a further bearing cage as well as further rolling elements 13, 14. A spring element 15 is furthermore shown in the unmounted state.

(16) To assemble the bearing device, as can be seen from a comparison of FIG. 2 and FIG. 3, the bearing cage 7 with the corresponding rolling elements 8, 9 is first of all mounted on the inner bearing element 5 of the shaft 2. In the simplest case, the bearing ring 7 is simply pushed on. The rolling elements 8, 9 can be designed as balls but can also be in any other known form of rolling elements.

(17) FIG. 4 shows that, after the bearing cage 7, the two bearing sleeve elements 10, 11 as a combined interconnected component are pushed onto the shaft 2 until the first bearing sleeve element 10 is situated above the first inner bearing element 5 in such a way that the rolling elements 8, 9 can run on the running surfaces/raceways of the bearing, which are formed by the inner bearing ring and the first bearing sleeve element.

(18) In FIG. 5, it can be seen that, after the two bearing sleeve elements 10, 11, the second bearing cage 12 with the corresponding rolling elements 13, 14 is mounted on the shaft 2, such that the rolling elements 13, 14 come to rest on the inner running surface/raceway of the second inner bearing element 6. For this purpose, the second bearing sleeve element 11 is moved closer to the first bearing sleeve element 10 than would correspond to its end position.

(19) The two bearing sleeve elements 10, 11 can be moved axially relative to one another, one inside the other or on a common guide sleeve, in the manner of a telescope and, in the illustration in FIG. 5, mounted together and pushed together axially, thus allowing the second bearing cage 12 with the bearing elements 13, 14 to be moved easily to its position in the region of the second inner bearing element 6.

(20) In the next step, as can be seen in FIG. 6, the two bearing sleeve elements 10, 11 are pushed apart axially until the second bearing sleeve element 11 comes to rest with its running surface/raceway above rolling elements 13, 14. Moreover, it is possible to apply to the second bearing element 11 an axial preload such that the rolling elements of both rolling bearings rest without play or with a defined play on the corresponding running surfaces. The two bearing sleeve elements 10, 11 can thereupon be connected to one another, for example, e.g. by means of known joining techniques, such as brazing, welding, adhesive bonding, clamping, latching by means of latching elements or screwing.

(21) As a preferred option, it is also possible, for example, to configure the two bearing sleeve elements 10, 11 in such a way, by means of a screwed joint or thread-type complementary shaping in the region of their axial overlap, that they can be moved axially relative to one another by screwing relative to one another.

(22) For example, the bearing sleeve elements can have mutually facing oblique end faces which slide on one another in a screw-like manner during a rotary movement. If the screw profile is self locking, it is possible for the spacing in the axial direction to be set by means of this profile.

(23) In principle, there is the advantageous possibility, with or without a guide sleeve of this kind, of bracing the two bearing sleeve elements 10, 11 relative to one another in the axial direction by means of a spring element 15. In the illustrative embodiment shown, the bearing sleeve elements 10, 11 are, as can be seen in FIG. 7, capable of being screwed relative to one another and are each provided with shoulders 10a, 11a, which can be braced with respect to one another, by means of a spring element 15 extending and flexing in the circumferential direction, by a spring force is acting in the circumferential direction and/or in the axial direction. The ends of the bearing sleeve elements are helically beveled and matched to one another in complementary fashion, thus ensuring that the ends slide on one another during a screwing movement and that a relative rotary movement of the bearing sleeve elements is converted into an axial movement.

(24) FIG. 8 shows a spring 15 in the unmounted state, wherein the spring is in the form of a circular ring segment with two bent ends 15a, 15b projecting radially inward and radially with respect to the shaft. The radially inward-bent ends 15a, 15b project over the shoulders 10a, 11a of the bearing sleeve elements 10, 11 and brace the latter relative to one another in the circumferential direction of the shaft 2.

(25) FIG. 9 shows the two bearing sleeve elements 10, 11 in a side view, wherein the spring element 15 can be seen between them, said spring allowing a further rotation of the two bearing sleeve elements only by overcoming the spring force, the coupling of the screwing movement with an axial relative movement between the bearing sleeve elements thus also ensuring an axial preload. This provides a stable bearing assembly, which allows a permanent setting of two rolling bearings relative to one another in the axial direction, e.g. for use in turbocharger devices, in such a way that the rolling elements rest without play on the running surfaces and low-wear and low-friction running of the shaft is hence achieved, even at high speeds of rotation and at varying temperatures.