GB2136092A

GB2136092A - Device for the Automatic Positioning of Angular-contact Bearings or for a Driven Shaft

Info

Publication number: GB2136092A
Application number: GB08404792A
Authority: GB
Inventors: Dietmar Frase
Original assignee: SKF Kugellagerfabriken GmbH
Current assignee: SKF GmbH
Priority date: 1983-02-23
Filing date: 1984-02-23
Publication date: 1984-09-12
Also published as: GB8404792D0; FR2541393A1; DE3306267A1; GB2136092B; FR2541393B1

Abstract

A shaft (12) driven via a power-transmitting element (19) is provided with a bearing ring (4) axially displaceable relative to a further bearing ring (5), and which, as a result of the moment of reaction, receives via the power-transmitting element (19) a force for axial displacement. To ensure that an automatic positioning of the two rings of angular-contact bearings (2, 3) dependent on the magnitude of the torque is effected, circumferentially spaced rolling bodies (28) are arranged at the output end of the power-transmitting element (19). For wedging in one or in both circumferential directions, these rolling bodies (28) are installed in respective axial recesses, each provided with an angular contact surface for the rolling body (28) in one or in both directions of rotation, in at least one of two axially opposite end faces (26, 27) between the power-transmitting element (19) and the axially displaceable bearing ring (4) connected with the shaft (12) in a manner precluding relative rotation. <IMAGE>

Description

SPECIFICATION Device for the Automatic Positioning of Angular-Contact Bearings, Positioned Mutually in Pairs, of a Plain or Rolling Bearing Assembly for a Driven Shaft The present invention relates to a device for the automatic positioning of angular-contact bearings, positioned mutually in pairs, of a plain or rolling bearing assembly for a driven shaft, in accordance with the preamble of Claim 1.

In a known device of type indicated the force for the axial displacement controlled by the torque is produced by a power-transmitting element which via an internal thread is connected with a corresponding counter thread of the shaft (DE-PS 26 30 035). In this known device the torque of the power-transmitting element can be transmitted to the shaft from the thread pitch of the power-transmitting element only in one direction of rotation. Moreover, the known device occupies a relatively large amount of space in axial direction, which is not available in many applications.

The invention characterised in Claim 1 is based on the object of devising a device of the type indicated, which effects automatic positioning, dependent on the magnitude of the torque, of the two angular-contact bearings even if the torque changes its direction of rotation. Furthermore, the device is intended to take up relatively little space.

With the device of the invention it is achieved, even with varying direction of rotation, that the two angular-contact bearngs always receive sufficiently high mutual preloading automatically controlled by the corresponding force for axial displacement. In the case of low torque loads the two angular-contact bearings are stressed to a relatively small extent by the preloading, so that the angular-contact bearings have advantageously low bearing friction. However, in the case of high torque loads the two angular-contact bearings are stressed by a high preloading. This high preloading prevents the bearing rings of the two angular-contact bearings from being mutually displaced as a result of high radial and axial forces, e.g. tooth forces from gears, which can cause bearing noise in operation and undesirable displacement of the shaft in the two angularcontact bearings.

Advantageous developments of the invention are characterised in the sub-claims.

A compact device is developed with the features according to Claim 2, which, during temporary load removal or upon changing the direction of rotation, prevents the rolling bodies from sliding without loading on the outer flat end face of the axially displaceable bearing ring. Thus during load removal the elastic coupling ring presses via the axially displaceable bearing ring against the rolling bodies so that they are always loaded axially and thus effect a coupling connection between the load-transmitting element and the axially displaceable bearing ring.

Claim 3 characterises a further device likewise of particularly compact construction. Here the rolling bodies are installed between the two angular-contact bearings and are thus protected from dirt ingress or damage from the outside.

The additional development according to Claim 4 incorporates a structural simplification of the device.

With the development of the device according to Claim 5 it is achieved that the rolling bodies have a linear contact with the angular contact surfaces of their recess, so that they can transmit relatively high force without the danger of overloading between the power-transmitting element and the coupling element.

The design of the device according to Claim 6 has the result that the load-transmitting element is guided concentrically on the journal of the shaft and can thus carry out small rotational movements relative to the shaft, which can be caused by displacement of the rolling bodies in their recesses during operation.

With the development according to Claim 7, the shaft or the driven members connected thereto is prevented from being overloaded and correspondingly damaged by an inadmissibly high torque. The spring element, e.g. conical spring, which is relatively stiff in relation to the elasticity of the coupling ring, has the effect that the powertransmitting element is displaced axially as a result of the correspondingly high force for axial displacement against the force of the spring element and is moved away from the outer end face of the axially displaceable bearing ring acting as coupling element.The rolling bodies then emerge from their associated recess in the end face of the power-transmitting element and thus automatically release the connection, precluding relative rotation, between the driving powertransmitting element and the axially displaceable bearing ring of the relevant angular-contact bearing.

The additional developments according to Claims 8, 9 and 10 incorporate further constructional simplifications of the device.

The device according to the invention for the automatic positioning of angular-contact bearings, positioned mutually in pairs, of a plain or rolling bearing assembly for a driven shaft will be explained in more detail in the following description of two examples of embodiment, with reference to the drawings, wherein:: Figure 1 shows a longitudinal section through a bearing assembly of a shaft carrying a bevel gear; Figure 2 shows a longitudinal section through the elastically compressible coupling ring illustrated in Figure 1, which is installed between the axially displaceable bearing ring and a shoulder of the shaft; Figure 3 shows a cross-section along the line Ill-Ill through the coupling ring illustrated in Figure 2; Figure 4 shows a plan view of the inner end face, provided with axial recesses for the rolling bodies, of the power-transmitting element illustrated in Figure 1; Figure 5 shows a longitudinal section along the line V-V through the power-transmitting element shown in Figure 4;; Figure 6 shows a partly sectional view of the power-transmitting element along the line VI--VI in Figure 5, and Figure 7 shows a longitudinal section through a modified bearing assembly of a shaft having an external toothing.

In Figure 1 the reference numeral 1 designates a housing and the two angular-contact bearings of a rolling bearing assembly are designated 2 and 3. In the present case, the two angularcontact bearings 2, 3 are designed as single-row tapered roller bearings, each of which has respectively an inner bearing ring 4, 5, an outer bearing ring 6, 7 and tapered rollers 8 arranged therebetween. The lines of force action 9, 10 of these angular-contact bearings 2, 3 positioned mutually in pairs extend radially outwards mutually convergent. Here the two outer bearing rings 6, 7 are retained and supported at a certain axial distance apart by an annular rim 11 projecting radially inwards in the bore of the housing 1.

The driven shaft 12 is mounted by the two angular-contact bearings 2, 3. The shaft 12 carries at its output end a bevel gear 13. The inner bearing ring 5 of the angular-contact bearing 3 at the output end, which bearing abuts outwardly against a shoulder face 14 of the shaft 12, is seated with an interference fit on the circumferential surface of the shaft 12. However, the inner bearing ring 4 of the angular-contact bearing 2 at the input end is retained with a sliding fit on the circumferential surface of the shaft 12. It can thus be moved axially relative to the inner bearing ring 5 of the angular-contact bearing 3 at the output end and can also carry out small relative movements on the shaft 12.

An axially elastically compressible coupling ring 15, which may be made of spring steel, is arranged between the two inner rings 4, 5. This coupling ring 1 5 abuts at the input end against the nearest end face of the axially displaceable bearing ring 4 and at the output end against the shoulder face 16 of a radial shoulder of the shaft 12 (Figure 2). At both its axial ends the coupling ring 1 5 has peripherally arranged axially projecting retaining lugs 17, 1 8 which engage in form-locking manner in corresponding axial recesses respectively in the end face of the bearing ring 4 and in the shoulder face 16 (Figure 3).In this way, the coupling ring 1 5 is connected, in a manner precluding relative rotation, at its input end to the axially displaceable inner bearing ring 4 and at its output end to the shaft 12.

The annularly shaped power-transmitting element 1 9 is fitted and rotatably mounted on the input-end journal of the shaft 12. By means of a shaft nut 20 and a spring element 21, which in the present case is in the form of a conical spring, the power-transmitting element 1 9 is secured against removal from the shaft 12. On its periphery the power-transmitting element 1 9 has four axially continuous threaded holes 22 (Figures 4 and 5). By means of screws 23, which are screwed into these threaded holes 22, the flange of a drive unit 24 is securely connected with the power-transmitting element 1 9. A torque can thus be transmitted from the drive unit 24 to the power-transmitting element 1 9.

A sealing ring 25 fitted in the housing 1 slides on the circumferential surface of a shoulder of the power-transmitting element 1 9.

Four cylindrical rolling bodies 28 are disposed uniformly spaced apart on the periphery between the outer flat end face 26 of the axially displaceable bearing ring 4 and the output-side flat end face 27 of the power-transmitting element 1 9 lying axially and parallel opposite thereto. The axes of rotation of these rolling bodies 28 extend in radial direction. As shown particularly clearly in Figures 5 and 6, the rolling bodies 28 (indicated in chain line) are retained in respective recesses 31 in the end face 27, provided in one direction of rotation with an angular contact surface 29 and in the opposite direction of rotation with an angular opposed contact surface 30.In the present example of embodiment the rolling bodies 28, which are installed between the end face 27 and the end face 26, can produce a wedging connection necessary for torque transmission, by respectively abutting in one direction of rotation against the angular contact surfaces 29 and in the other direction of rotation against the angular contact surfaces 30. A torque is thus transmitted from the power-transmitting element 1 9 via the rolling bodies 28 to the axially displaceable inner bearing ring 4 and from the inner bearing ring 4 via the coupling ring 1 5 to the shaft 12.

As a result of the moment of reaction, the normal force 32 will be exerted via the respective angular contact surface 29 and 30 on to each rolling body 28, which normal force produces as a reaction at the flat end face 26 of the bearing ring 4 a force for the axial displacement 33 (Figure 6).

In the present case, the force for the axial displacement 33 produced by the rolling bodies 28 will be transmitted directly to the axially displaceable bearing ring 4. The magnitude of the force for the axial displacement 33 is dependent on the magnitude of the relevant peripheral force 34 of the torque. The greater the torque of the power-transmitting element 19, the greater will be the force for the axial displacement 33 of each rolling body 28. The angle of inclination a of both contact surfaces 29, 30 is sufficiently small so that in the contact between each rolling body 28 and the flat end face 26 of the bearing ring 4 a self-retaining friction occurs during transmission of a torque (without the rolling bodies slipping. If temporarily no torque is transmitted from the power-transmitting element 19, the rolling bodies 28 are loaded.axially by the coupling ring 1 5 which presses against the inner end face of the bearing ring 4. The rolling bodies 28 then receive through the coupling ring 1 5 a slight axial minimum loading which, when the shaft 12 is temporarily not being driven, prevents the rolling bodies 28 from slipping on the flat end face 26 of the bearing ring 4 and thereby being subject to wear.

In the event of inadmissibly high torque, a relatively great force for the axial displacement 33 will be produced by each rolling body 28. This considerable force for the axial displacement 33 urges the power-transmitting element 1 9 axially outwards against the force of the spring element 21. Finally, the rolling bodies 28 are moved out of their recesses 31 and thus automatically release the connection, precluding relative rotation, between the power-transmitting element 1 9 and the inner bearing ring 4 (overload protection).

With automatic positioning of the angularcontact bearings 2, 3 of the rolling bearing, positioned mutually in pairs, for the shaft 12 driven via the power-transmitting element 19, both the resultant force for the axial displacement 33 and the driving torque of the powertransmitting element 19 are respectively produced and transmitted by the four rolling bodies 28 which are spaced apart peripherally and wedged in peripheral direction.This force production and transmission is effected by the rolling bodies 28 wedged between respectively an axial recess 31 of the inner end face 27 of the power-transmitting element 19, which recess is provided with an angular contact surface 29, 30 for the relevant rolling body 28 in both directions of rotation, and the outer end face 26, lying axially opposite this end face 27, of the axially displaceable bearing ring 4 rotatable relative to the shaft 12.

Figure 7 illustrates a modified device. This device comprises, like the device in the abovedescribed example of embodiment, a housing 1 and two angular-contact bearings 2, 3 fixed in the bore of the housing 1. The two angular-contact bearings 2, 3 are provided respectively with an inner bearing ring 4, 5, an outer bearing ring 6, 7 and tapered rollers 8 disposed therebetween. The lines of force action 9, 10 of the two angularcontact bearings 2, 3 extend radially outwards mutually convergent. In the present example of embodiment, the power-transmitting element 1 9 is of sleeve-like design and is connected with the axially displaceable inner bearing ring 4 of one angular-contact bearing 2, which is seated on the circumferential surface of the power-transmitting element 1 9.At the input end of the powertransmitting element 19 a flanged ring 35, held in the bore of the inner bearing ring 4, is secured by screws 36 to the power-transmitting element 1 9.

The displaceable inner bearing ring 4 is retained axially and secured against separation from the power-transmitting element 1 9 by a shoulder face 37 of the flanged ring 35.

The flanged ring 35, which is rigidly coupled by screws 39 to a corresponding flange 38 of the drive unit 24, receives from the driving unit 24 the torque driving the shaft 12. The shaft nut 20 is screwed on at the journal end of the shaft 12, which nut secures axially on the shaft 12 the structural unit comprising the power-transmitting elements 19, the flanged ring 35 and the inner bearing ring 4. A washer 41 consisting of elastically compressible rubber or the like is disposed between the shaft nut 20 and the outer end face 40 of the flanged ring 35. Because of its inherent elasticity, this washer 41 allows with torsional resilience slight relative rotational movements between the shaft nut 20 and the end face 40 (without sliding friction).

The flanged ring 35 and the powertransmitting element 19 are secured for sliding rotational movement on the journal of the shaft 12. Lubrication grooves 42 in the bore of the power-transmitting element 1 9 and of the flange 35 retain the lubricant (grease) in the sliding clearance between the bore of the powertransmitting element 19 and the journal of the shaft 12.

The inner bearing ring 5 of the other angularcontact bearing 3 is seated with an an interference fit on the circumferential surface of a sleeve-like coupling element 43. This coupling element 43 has at its end nearest the angularcontact bearing at the input end a radially inward facing flange 44.

The recesses 31 are provided on the end face of the flange 48 of the power-transmitting element 1 9 facing the axially displaceable bearing ring 4. The end face of the flange 44 of the coupling element 43 cooperating therewith via the cylindrical rolling bodies 28 faces axially outwards, i.e. away from the axially displaceable bearing ring 4. The end face of the coupling element 43 likewise has peripherally spaced recesses 45. In each case a recess 31 of the end face of the power-transmitting element 1 9 lies axially opposite a recess 45 of the coupling element 43. The individual rolling bodies 28 are disposed in the recesses 31,45 lying opposite one another, so that these rolling bodies are also retained radially in these recesses 31,45.

During torque transmission through the powertransmitting element 19, the rolling bodies 28 are wedged between the angular contact surfaces facing the relevant circumferential direction of the two recesses 31,45. They thus transmit the torque from the power-transmitting element 19 to the coupling element 43. At the same time, the rolling bodies 28 produce a force for mutual axial displacement, which acts between the end face of the power-transmitting element 1 9 and the end face of the coupling element 43 and endeavours to urge these two end faces away from one another. The two inner bearing rings 4, 5 are thus loaded and positioned mutually axially inwards.

Upon changing direction of rotation, the circumferentially opposed angular contact surfaces of the two recesses 31,45 of each rolling body 28 are loaded. Once again a force for the mutual axial displacement is thereby transmitted through the rolling bodies 28 to the power-transmitting element 1 9 and the coupling element 43. The two bearing rings 4, 5 are mutually positioned with this force for axial displacement. The rolling bodies 28 can thus be shifted slightly from the angular contact surfaces of the previous direction of rotation to the circumferentially opposed angular contact surfaces 31,45 of each recess. The powertransmitting element 19 then undergoes a slight sliding rotation on the journal of the shaft 12.

The sleeve-like coupling element 43 is connected, in a manner precluding relative rotation, via an internal toothing 46 in its bore to an external toothing 47 of the shaft 12 engaging therein.

The above-described devices for the automatic positioning of angular-contact bearings, positioned mutually in pairs, of a plain or rolling bearing assembly for a driven shaft can be modified structurally. For example, the lines of force of the two angular-contact bearings may be so aligned that they extend radially outwards mutually divergent. In this case, in the example of embodiment illustrated in Figure 7 the axial recesses for the rolling bodies will then be incorporated in the opposite end faces of the relevant flanges. During torque transmission, the inner bearing rings of the two angular-contact bearings will thus be urged axially apart by the force for the axial displacement of the rolling bodies and mutually positioned.

Moreover, the two angular-contact bearings do not need to be designed as rolling bearings.

Instead, at least one of the two angular-contact bearings may be designed as a hydrodynamic or hydrostatic plain bearing with correspondingly tapered sliding surfaces.

In the example of embodiment illustrated in Figures 1 to 6, the rolling bodies 28 roll in peripheral direction between the flat end face 27 of the power-transmitting element 19 and the axially opposite flat end face 26 of the inner bearing ring 4, when they have left their recesses 31 as a result of overloading. In this case it can be advantageous to install the rolling bodies 28 in a per se known cage which is disposed between the two end faces 26, 27 situated axially opposite one another and which retains the rolling bodies 28 at a given circumferential distance apart between the two end faces 26, 27, even after they have left the associated recesses 31.

If the axial recesses are provided only with one angular contact surface in one direction of rotation, they may be provided alternately on the periphery with a contact surface for rolling bodies effective for one direction of rotation and for the direction of rotation opposite thereto. In this case, one part of the rolling bodies arranged on the periphery transmits exclusively the torque acting in one direction of rotation and the other part the torque acting in the other direction of rotation. Per se known spring elements (leaf springs etc.) may then be installed in each axial recess of one of the two end faces between the power-transmitting element and the bearing ring, connected in a manner precluding relative rotation, or the coupling element, which position without play the relevant rolling body in peripheral direction against its angular contact surface. For the case in which the rolling bodies are retained spaced apart in a cage, these spring elements may be installed in the cage so that the spring elements abut against the cage.

The torque produced by the rolling bodies 28 may also be transmitted directly to the shaft 12 through an axially displaceable bearing ring acting as coupling element, i.e. without a further coupling element 1 5. In this case, the axially displaceable inner bearing ring 4 may be connected, axially displaceably and in a manner precluding relative rotation, via an internal toothing in its bore to an external toothing of the shaft (splined shaft) engaging therein.

Claims

1. Device for the automatic positioning of angular-contact bearings, positioned mutually in pairs, of a plain or rolling bearing assembly for a shaft driven via a power-transmitting element, wherein one of the two angular-contact bearings is provided with a bearing ring which is axially displaceable relative to the corresponding bearing ring of the other angular-contact bearing and which, as a result of the moment of reaction, receives via the power-transmitting element a force for the axial displacement, characterised in that peripherally spaced rolling bodies (28) are arranged between the output-side end of the power-transmitting element (19) and the axially displaceable bearing ring (4), connected to the shaft (12) in a manner precluding relative rotation, or a coupling element (1 5, 43) connected with the axially displaceable bearing ring (4) and directing the torque to the shaft (12), which rolling bodies so as to be wedged in one or in both peripheral directions are installed in respective axial recesses (31, 45), each of which is provided with an angular contact surface (29, 30) for the respective rolling body (28) in one or both directions of rotation, in at least one of the two axially opposite end faces (26,27) of the power-transmitting element (19) and of the bearing ring (4) or of the coupling element (15, 43).

2. Device according to Claim 1, characterised in that the rolling bodies (28) are arranged between an outer flat end face (26) of the axially displaceable bearing (4) and an inner end face (27) of the power-transmitting element (19) lying parallel opposite thereto, and in that the coupling element is formed by an axially elastically compressible coupling ring (15) which at its input end is securely connected with the inner end face of the displaceable bearing ring (4) coupled via the rolling bodies (28) to the power-transmitting element (19) and sliding on the shaft (12), and which-at its driven end is securely connected with the shaft (12).

3. Device according to Claim 1, characterised in that the power-transmitting element (19) is of sleeve-like design and on its circumferential surface carries the axially displaceable bearing ring (4) of one angular-contact bearing (2) and at its end arranged between the two angular-contact bearings (2, 3) carries a radially outward facing flange (38) which on the corresponding side is provided with the end face provided with axial recesses (31) for the rolling bodies (28), and in that the corresponding bearing ring (5) of the other angular-contact bearing (3) is seated on the circumferential surface of a sleeve-like coupling element (43) which at its end nearest the angularcontact bearing (2) has a radially inward facing flange (44) with an end face situated axially opposite the end face of the power-transmitting element (19).

4. Device according to Claim 3, characterised in that the sleeve-like coupling element (43) is connected, in a manner precluding relative rotation, via an internal toothing (46) in its bore with an external toothing (47) of the shaft (12) engaging therein.

5. Device according to any of the preceding Claims, characterised in that the rolling bodies (28) are of cylindrical design and the axial recesses are formed by radially extending grooves (31) of V-shaped cross-section arranged uniformly on the periphery.

6. Device according to any of the preceding Claims, characterised in that the powertransmitting element (19) is of annular design and is arranged rotatably on the shaft (12).

7. Device according to any of the preceding Claims, characterised in that the powertransmitting element (19) is connected with a spring element (21) which is secured on the shaft (12) and which presses it via the rolling bodies (28) against the outer end face (26) of the axially displaceable bearing ring (4).

8. Device according to any of the preceding claims, characterised in that the two angularcontact bearings (2, 3) are arranged with radially outwards mutually convergent lines of force action (9, 10).

9. Device according to claims 3 and 8 or 4 and 8, characterised in that the recesses (31) are disposed on that end face of the flange (38) of the power-transmitting element (19) facing towards the axially displaceable bearing ring (4).

10. Device according to any of the preceding claims, characterised in that the rolling bodies (28) are installed in a cage which retains them at a mutual circumferential distance apart between the two axially opposite end faces (26, 27) of the power-transmitting element (19) and of the axially displaceable bearing ring (4) or coupling element (43).

11. A device substantially as herein described with reference to and as shown in Figures 1 to 6 or with reference to and as shown in Figure 7 of the accompanying drawings.