WO2008083651A1

WO2008083651A1 - Roller bearing device comprising a roller bearing with an outer ring operated under axial preload

Info

Publication number: WO2008083651A1
Application number: PCT/DE2007/002233
Authority: WO
Inventors: Gordana Michos
Original assignee: Schaeffler Kg
Priority date: 2007-01-12
Filing date: 2007-12-11
Publication date: 2008-07-17
Also published as: DE102007001918A1

Abstract

Roller bearing device comprising a roller bearing with an outer ring operated under axial preload, provided with a device (11) for compensating for the thermal changes to radial preload, comprising an expanding tapered ring (12) which may be axially displaced on the outer ring (4) of the roller bearing (2) which is axially preloaded by means of a tensioning element (18) which runs with the tapered surface (14) thereof on a further annular tapered surface (15).

Description

Rolling bearing device comprising a rolling bearing operated under radial prestress with an outer ring

description

Field of the invention

The invention relates to a rolling bearing device comprising a rolling bearing operated under radial prestress with an outer ring.

Background of the invention

Such a rolling bearing device is used, for example, where a shaft is rotatable relative to a housing to store. In this case, there is often a considerable difference in temperature between the shaft and the housing which is frequently cooled during operation, with this temperature gradient also having an effect on the temperatures of the inner and outer rings, between which a temperature difference is thus likewise given. In rolling bearing devices of the type in question with radial preload of the bearing, this temperature difference leads to a change in the set bearing preload, that is, the bearing preload decreases during operation or at a cooling of the rolling bearing unit again. The preload of the bearings is limited by the operating condition.

DE 1 813 409 A1 discloses a device for maintaining the axial bearing play in rolling bearing devices, comprising two wedge rings made of different materials which have different coefficients of expansion, that is to say they have a different temperature behavior. The two wedge rings are arranged in the region of the outer ring. Due to the different coefficients of expansion results in a different expansion behavior at a corresponding temperature, which results in an axial movement due to the tapered ring arrangement, from which an axial load of the outer ring is made possible. So here only axial bearing clearance can be varied.

Summary of the invention

The invention is therefore based on the problem to provide a rolling bearing device, which offers the possibility of compensation of thermally induced voltage changes in radially biased or radially loaded bearings.

To solve this problem is in a rolling bearing device of the type mentioned according to the invention for compensating thermally induced changes in the radial bias comprising an axially displaceable on the outer ring of the bearing, axially biased by a clamping element, expandable wedge ring, with its wedge surface on a further annular Wedge surface running, provided. In the rolling bearing device according to the invention, a bias voltage is generated on the outer ring on the expandable wedge ring, which in turn is radially biased with respect to the inner ring. If, due to a temperature difference between the warmer inner ring and the colder outer ring, an increase in the bearing preload arises due to the stronger thermally induced widening of the inner ring, the outer ring, because overlapped by the expandable wedge ring, can in turn expand somewhat, resulting in a corresponding widening of the wedge ring results. That is, the increase of the bearing preload caused by the temperature gradient is dissipated into the wedge ring so that, overall, a substantially constant bearing preload also results when a temperature gradient is applied, since any voltage increases can be dissipated via the wedge ring.

In order to allow widening of the wedge ring, the wedge ring is slotted axially at least once, so it is interrupted at at least one point in the circumferential direction. Conceivable, however, would be an embodiment of a wedge ring made of a correspondingly soft material that allows expansion.

With regard to the arrangement or design of the further annular wedge surface, different embodiments are conceivable. According to a first alternative of the invention, the further wedge surface may be provided on a further wedge ring which engages around the outside of the first wedge ring. This further wedge ring is fixed axially and radially, so that the first wedge ring with its wedge surface can slide along the wedge surface of the second wedge ring, wherein it moves axially relative to the outer ring.

An inventive alternative provides to provide the additional wedge surface on a subsequent to the rolling bearing housing component. This housing component may be of any nature, it may be a genuine housing portion, but it may also be a sleeve or the like. In any case, it is a component on which axially protrudes a wedge with a corresponding wedge surface, or on the radially projecting a wedge projecting towards the bearing with a corresponding wedge surface.

A third alternative of the invention provides to provide the wedge surface directly on the outer side of the outer ring itself, thus, therefore, to use the bearing ring as a wedge ring guide part.

As described above, the wedge ring is axially biased by a clamping element. About this clamping element it is opposed to a resistance that must be overcome during expansion, so that the axial movement of the wedge ring is possible. This clamping element can be designed according to a first embodiment of the invention as a spring element. It may be a plate spring, one or more coil springs or one or more leaf springs or the like. The tensioning element can also be designed as an annular disc made of a material with lower rigidity than steel.

Alternatively to the use of an axially prestressing spring element, the tensioning element can also be a piezoelectric actuator or a tensioning element consisting of a shape memory alloy or a hydraulic or pneumatic actuator. Using a piezoelectric actuator, the clamping of the wedge ring by electrical control of this piezoelectric actuator, which changes its shape due to voltage, over which the basic voltage can be built up. However, it is also conceivable to use a clamping element consisting of a shape memory alloy. As a shape memory alloy, for example, a NiTi or a CuZnAI alloy can be used. Such alloys are characterized by the fact that they make a shape change from reaching a certain temperature resulting from a structural change. It is therefore conceivable to use an existing of such a material clamping element, the at the usual operating temperature a certain, the Automatically takes tension-generating form. As a further embodiment, hydraulic or pneumatic actuators are conceivable, which also require a corresponding activation or supply of hydraulic fluid or a pressure medium, for example air.

Finally, the outer ring is suitably secured by an anti-rotation, so that it does not rotate with a rotation of the shaft in which the inner ring is entrained.

Brief description of the invention

Further advantages, features and details of the invention are described below with reference to embodiments with reference to the figures. The figures are schematic representations and show:

1 is a schematic diagram of a rolling bearing device according to the invention of a first embodiment, partly in section,

Fig. 2 is a schematic representation of a rolling bearing device according to the invention a second embodiment, partly in section, and

Fig. 3 is a schematic representation of a rolling bearing device according to the invention a third embodiment, partly in section.

Detailed description of the drawings

1 shows a schematic representation of a Wälzlagerein- direction 1 of a first embodiment. It comprises a roller bearing 2 comprising an inner ring 3 and an outer ring 4, wherein the inner ring 3 is arranged on a shaft 5 axially fixed against a stop point 6 rotatably. The outer ring 4 in turn is rotatably connected via a rotation 7 with a housing 8, so that in a shaft rotation, only the inner ring 3 and the rolling elements 19 move, but not the outer ring 4. The outer ring 4 is in turn arranged in a fixed position in the housing, which has a corresponding housing wall 9 and a cover plate 10, in which also the anti-rotation device 7 is arranged, for example a small dowel pin or the like.

Further provided is a device 11, can be compensated by the thermally induced voltage changes in the radial direction. This device 11 comprises a wedge ring 12 which is arranged axially displaceably on the outer side 13 of the outer ring 4. The wedge ring 12 is slotted axially at least once so that it can widen. With its wedge surface 14 it runs on the wedge surface 15 of a second wedge ring 16, which in turn is received in a fixed position in the housing 8 on a corresponding annular component 17. The two wedge surfaces 14, 15 thus run on each other. The first wedge ring 12 is further biased axially via a clamping element 18, here for example a plate spring, over this it is pressed with its wedge surface 14 against the wedge surface 15.

About the wedge ring 12, a radial stress is now placed on the outer ring 4. If now a temperature gradient between the inner ring 3 and the outer ring 4, which during operation, for example when using the

Rolling bearing device 1 in a motor or the like may well be the case, so the inner ring 3 expands, as it is warmer, slightly stronger than the colder outer ring 4. This causes the bias between see inner ring 3 and outer ring 4, which has been set in a defined, cold state of both rings, is increased, this bias, the outer ring 4 would be stored directly radially in the housing, complete would be absorbed by the outer ring 4 and would increase excessively, so that ultimately the wear increases significantly.

In the example shown, however, the increase in bias via the device 11 according to the invention can be compensated or reduced. For, on the one hand radially enough to the outer ring 4 is still sufficient space in which the outer ring 4 can expand. The increased bias voltage is now absorbed by the wedge ring 12 and derived therefrom. The load also slightly elongated outer ring 4 due to the expansion of the inner ring 3 is now in turn stretches the first wedge ring 12, which, as slotted, something expands. This radial enlargement causes the wedge surface 14 on the fixed wedge surface 15, starting from the example according to FIG. 1, to slide off to the right, that is to say the wedge ring 12 is pressed against the clamping element 18, compressing it. In this case, the spring force is designed so that at a temperature-induced increase in the bias both the spring force and the frictional force between the wedge surfaces 14, 15 and the outside 13 is overcome and it comes to the axial displacement of the wedge ring 12. This shift thus allows the radial expansion of the bearing ring, whereby an overload caused by the temperature increase due to bias increase of the bearing is advantageously avoided.

FIG. 2 shows a further embodiment of a roller bearing device 1, which fundamentally corresponds in construction to that of FIG. 1. While 19 cylindrical rollers are shown in Fig. 1 as rolling elements, it is in the rolling bearing 2 in Fig. 2 is a tapered roller bearing. As can be seen, here the rolling elements 19 are designed as oblique rollers, the inner ring 3 and the outer ring 4 have correspondingly executed Wälzkörperlaufbahnen on. As a result of the change in geometry of the outer ring 4, the anti-rotation 7 is also provided on the other side of the housing 8 here. However, here too the device 11 according to the invention for compensating or for reducing the increase in bias resulting from a temperature gradient is comprehensively send the first wedge ring 12 and the second wedge ring 16 with their respective wedge surfaces 14, 15 as well as the clamping element 18 is provided. Here too, therefore, a radial expansion of the outer ring 4 can take place, after this is made possible by reducing the increase in prestress via the first wedge ring 12 moving axially along the outer side 13 of the outer ring 4.

A further embodiment of a rolling bearing device 1 according to the invention is shown in FIG. 3. The local rolling bearing 2 is a ball bearing, the rolling elements 19 are thus designed spherical. Again, a device 11 is used to reduce or compensate for temperature-induced changes in bias used, but this includes only one wedge ring 12 with its wedge surface 14. The second wedge surface 15 is formed here on the outer side of the outer ring 4. If this results in a temperature-induced expansion of the outer ring 3, so here too the wedge ring 12 slides over the wedge surface 14 which runs on the wedge surface 15, to the right against the restoring force of the clamping element 18, which is compressed.

Instead of the clamping element 18 in the form of a spring or the like, it is also conceivable to load the wedge ring 12, for example, pneumatically or hydraulically, thus biasing it via a pneumatic or hydraulic control. The use of a piezoelectric actuator for generating the Keilringvorspannung or a clamping ring of a shape memory alloy is conceivable.

Overall, the rolling bearing device according to the invention allows for the degradation of bias changes generated by a temperature gradient, after allowing this allows the bearing outer ring radially seen slightly widen, while at the same time over the wedge ring a sufficient bias is applied to the bearing outer ring. However, this arrangement is useful not only with regard to a reduction of bias overshoots, but also to prevent any Slippage, since the rolling bearing, here the outer ring, is always acted upon by the wedge ring with a certain minimum force. Over the wedge ring so a minimum bias is applied continuously, optionally in addition to the system immanent bias.

LIST OF REFERENCE NUMBERS

1 rolling bearing device

2 rolling bearings

3 inner ring

4 outer ring

5 wave

6 stop point

7 anti-rotation lock

8 housing

9 housing wall

10 lens

11 setup

12 wedged ring

13 outside

14 wedge surface

15 wedge surface

16 wedged ring

17 ring component

18 clamping element

19 rolling elements

Claims

claims

1. rolling bearing device comprising a rolling bearing operated under radial prestress with an outer ring, characterized by means (11) for compensating for thermally induced changes in the radial bias comprising a on the outer ring (4) of the

Rolling (2) axially veschiebbaren about a clamping element (18) axially biased, expandable wedge ring (12) which runs with its wedge surface (14) on a further annular wedge surface (15).

2. Rolling bearing device according to claim 1, characterized in that the wedge ring (12) is slotted axially at least once.

3. Rolling bearing device according to claim 1 or 2, characterized in that the further wedge surface (15) on a further wedge ring (16) which surrounds the first wedge ring (12) on the outside, is provided.

4. Rolling bearing device according to claim 1 or 2, characterized in that the further wedge surface (15) is provided on a to the rolling bearing (2) adjoining housing member.

5. Rolling bearing device according to claim 1 or 2, characterized in that the wedge surface (15) is provided on the outer side of the outer ring (4) itself.

6. Rolling bearing device according to one of the preceding claims, characterized in that the clamping element (18) is a spring element or an annular disc made of a material having a lower rigidity than steel.

7. Rolling bearing device according to one of claims 1 to 5, characterized in that the clamping element (18) is a piezoelectric actuator or a shape memory alloy existing clamping element or a hydraulic or pneumatic actuator.

8. Rolling bearing device according to one of the preceding claims, characterized in that the outer ring (4) via an anti-rotation (7) is secured.