WO2009141232A1

WO2009141232A1 - Rolling bearing for a system for locking a motor vehicle steering column in position

Info

Publication number: WO2009141232A1
Application number: PCT/EP2009/055514
Authority: WO
Inventors: Jacques Delos; Bruno Montboeuf
Original assignee: Aktiebolaget Skf
Priority date: 2008-05-19
Filing date: 2009-05-07
Publication date: 2009-11-26
Also published as: FR2931218A1; DE112009001201T5

Abstract

The rolling bearing device is provided for a system for locking a motor vehicle steering column in position of the type comprising a locking shaft and a lever for controlling the said shaft. The device comprises first and second rings 32, 34, at least one row of rolling elements 36 which are arranged between raceways 40a, 46a of the said rings, and a holding cage 38 for maintaining a uniform circumferential spacing between the rolling elements. One of the rings 32 has a radial portion 40 provided with the raceway 40a, and an axial portion 42 comprising means 44 for axially retaining the device on the locking shaft. The holding cage 38 comprises means 60, 62 for axially retaining the first and second rings.

Description

Rolling bearing for a system for locking a motor vehicle steering column in position

The present invention relates to the field of rolling bearings, particularly the ones used in systems for locking steering columns o f motor vehicles in position.

Such locking systems are known per se and generally comprise a housing inside which the steering column is mounted, and a locking shaft which is connected to a control lever and which, by means of a cam system, makes it possible to clamp the steering column in the housing and immobilize it in the chosen position.

For further details on such locking systems, reference may be made, for example, to patents FR-B 1 -2 802 167 and US 5 , 377, 555.

In the locking systems disclosed in those documents, a rolling bearing is provided between the locking shaft and the housing inside which the steering column is mounted so as to facilitate the operation of the locking shaft. In those documents, a large number of parts are provided for fastening the rolling bearing, this resulting, furthermore, in a relatively large axial size. Therefore, the object of the present invention is to overcome these disadvantages.

More particularly, the present invention aims to provide a rolling bearing for a system for locking a motor vehicle steering column in position that is particularly simple, axially compact, economic to manufacture and easy to mount.

The present invention also aims to provide a rolling bearing in which the elements constituting it have a limited risk of coming apart.

The invention relates to a rolling bearing device for a system for locking a motor vehicle steering column in position of the type comprising a locking shaft and a lever for controlling the said shaft. The device comprises first and second rings, at least one row of rolling elements which are arranged between raceways of the said rings, and a holding cage for maintaining a uniform circumferential spacing between the rolling elements. According to a general feature, one of the rings has a radial portion provided with the associated raceway, and an axial portion comprising means for axially retaining the device on the locking shaft. The cage may comprise means for axially retaining the first and second rings. Hence, the operation of mounting the rolling bearing on the shaft of the system for locking the steering column in position can be carried out in a particularly straightforward manner. Specifically, this mounting operation takes place by way of the axial portion of one o f the rings which for this purpose comprises specific axial retention means. Moreover, the axial retention means make it possible to limit any possible risk of the rings, rolling elements and cage coming apart.

In one embodiment, the axial retention means comprise a threaded portion which leads out at at least one end of the axial portion and which is intended to engage with a corresponding threaded portion of the locking shaft.

Advantageously, the cage is produced in one piece. It may comprise a radial portion provided with housings or pockets for the rolling elements and internal and external axial portions each provided with means for axially retaining one of the rings. The axial retention means may comprise hooks extending radially in the direction of the rings.

In one embodiment, one of the rings comprises means whereby the said ring can be driven to rotate by a clamping tool. These driving means may comprise flats formed on the outer surface of the axial portion of the ring that comprises the means for axially retaining the device on the shaft. Alternatively, it is possible to provide passage holes formed on the radial portion of the said ring.

The invention also relates to a system for locking a motor vehicle steering column in position that comprises a locking shaft, a lever for controlling the said shaft, a housing inside which the steering column is mounted, and a rolling bearing device as defined above and provided between the said housing and the locking shaft.

The invention also relates to a steering column comprising a locking system as previously defined. The present invention will be better understood on studying the detailed description of embodiments which are given by way of non- limiting examples and which are illustrated by the appended drawings, in which:

- Figure 1 schematically represents a system for locking a steering column in position that comprises a rolling bearing according to a first embodiment of the invention,

- Figures 2 to 4 are a sectional view, a top view and an exploded perspective view, respectively, of the rolling bearing shown in Figure 1 , and - Figure 5 is a sectional view of a rolling bearing according to a second embodiment of the invention.

In Figure 1 , there is shown a system, referenced 10 overall, intended to allow a motor vehicle steering column 12, of axis 12a, to be maintained and locked in position. The system 10 primarily comprises a housing 14 in the form o f an inverted U inside which the steering column 12 is housed, a locking shaft 16, of axis 16a, and a control or operating lever 18 connected to the said shaft. The axis 16a is perpendicular to the axis 12a.

The steering column 12 is fastened by any suitable means, for example by welding, to a cradle 20 having two parallel legs 20a, 20b which can move inside two parallel legs 14a, 14b of the housing 14. The legs 14a, 14b of the housing 14 each comprise an oblong slot or opening 22, 24 for allowing access to holes (not referenced) made in the legs 20a, 20b of the cradle 20 which supports the steering column 12 and for allowing the shaft 16 to move in order to set the column 12 in the desired position. The diameter of the holes made in the legs 20a, 20b of the cradle 20 is substantially equal to the width of the openings 22, 24 provided on the legs 14a, 14b of the housing 14.

The locking shaft 16 extends between the legs of both the cradle 20 and the housing 14 by passing through the holes and the openings 22, 24 so as to project axially from either side of the said housing. The operating lever 18 is fastened securely to an axial end o f the locking shaft 16. A conventional cam means 26 with an axial action is arranged between the leg 14b of the housing 14 and the operating lever 18. A bearing 30 is fastened by way of one of its rings to the other projecting axial end of the shaft 16 and is mounted by its other ring to bear on the leg 14a of the housing 14. The bearing 30, o f axis 30a, is coaxial to the locking shaft 16.

The possible movement of the locking shaft 16 inside the openings 22, 24 in the legs 14a, 14b of the housing 14 makes it possible to adjust the position of the steering column 12 in terms of height. An upper position is represented by broken lines in the figure. The steering column 12 is then immobilized by means of the operating lever 18, the rotation of which actuates the cam means 26. An axial clamping force is thus exerted between the legs 14a, 14b of the housing and those of the cradle 20.

The bearing 30 for its part allows the locking shaft 16 to be able to turn freely with respect to the housing 14 while transmitting the axial clamping forces to the legs of both the said housing and the cradle 20. As illustrated more visibly in Figures 2 to 4, the bearing 30 comprises an external ring 32 and an internal ring 34 between which rolling elements 36, here in the form of balls, are housed, and a holding cage 38 for maintaining a uniform circumferential spacing o f the rolling elements 36. The term "internal ring" here is understood to mean the ring situated axially adjacent to the housing 14, and the term "external ring" is intended to mean the outwardly oriented ring.

The external ring 32 has a radial portion 40 which, in cross section, exhibits a concave internal profile capable of forming a toroidal raceway 40a for the row of rolling elements 36, this raceway being oriented axially inwards. The radial portion 40 is extended axially outwards, starting from a small-diameter edge, by an axial portion 42 provided with a threaded bore 44 capable of engaging with a corresponding thread 16b of the locking shaft 16 (Figure 1 ). The bore 44 passes axially right through the axial portion 42. In a variant, it could be possible to provide a bore 44 which leads out only at that end of the axial portion 42 situated adjacent to the internal ring 34. The external ring 32 may advantageously be formed by cutting and deep drawing or die stamping a sheet metal blank, the bore 44 then being tapped.

The internal ring 34 for its part consists of a washer 46 of U- shaped cross section so as to form a concave internal profile constituting a toroidal raceway 46a for the rolling elements 36, this raceway being oriented axially outwards. The internal ring 34 can be manufactured at lower cost by cutting and deep drawing or die stamping a thin sheet metal. On the opposite side axially to the raceway 46a, the internal ring 34 is intended to bear against the leg 14a of the housing. The external ring 32 is in this case rotating while the internal ring 34 is non-rotating. Of course, it could also be conceivable to provide a rotating internal ring and a non-rotating external ring.

The holding cage 38 of annular general shape is advantageously moulded in one piece from a synthetic material such as polyamide. In a variant, the cage 38 could be made of a metallic material, in particular steel.

The holding cage 38 comprises a radial portion 48 extended by internal 50 and external 52 axial portions. The radial portion 48 is situated axially between the internal ring 34 and the radial portion 40 of the external ring 32, and more precisely between the raceways 40a, 46a of the said rings. It comprises a plurality of pockets 54 which are formed across its thickness and which are intended to accommodate the rolling elements 36. The pockets 54 are uniformly spaced with respect to one another in the circumferential direction.

The internal axial portion 50 axially extends, on the opposite side to the external ring 32, a small-diameter free edge of the radial portion 48 and has a bore 56 whose diameter is greater than the diameter of the threaded bore 44 of the external ring 32. The internal axial portion 50 is situated in the vicinity of the small-diameter inner edge of the ring 34, leaving a slight radial clearance 58 between these two elements.

The internal axial portion 50 also comprises hooks 60 which extend radially outwards into the vicinity of the internal ring 34. The hooks 60 have a greater diameter than the inner edge of the ring 34 so that there is diametrical interference between these two parts at the hooks 60 and at the said inner edge. A slight axial clearance (not referenced) is provided between the hooks 60 and the inner edge of the ring 34.

The hooks 60 form means for axially retaining the internal ring 34 on the cage 38. The hooks 60 are uniformly distributed over the circumference of the axial portion 50 and situated axially on the opposite side to the external ring 32. Without any limitation being implied, there may be four hooks 60. Of course, it could be conceivable to provide a continuous or segmented radial bead in place of the hooks 60. The external axial portion 52 has an annular general shape and radially surrounds the external ring 32 and internal ring 34. Its axial dimension is substantially equal to the axial size of the internal ring 34 combined with the axial size of the radial portion 40 of the external ring 32 and the axial size of the rolling elements 36. The external axial portion 52 comprises, at the axial end situated adjacent to the external ring 32, hooks 62 which are provided on its internal bore and which extend radially inwards. The hooks 62 have a smaller diameter than the large-diameter outer edge of the radial portion 40 of the external ring 32 so that there is diameter interference between these two parts. The hooks 62 thus form means for axially retaining the external ring 32 on the holding cage 38. A slight axial clearance (not referenced) is provided between these hooks and the outer edge of the ring 32. The hooks 62 are uniformly spaced with respect to one another and there are four of them in this case. Of course, as an alternative, it could be possible to provide a continuous or segmented radial bead as a replacement for the hooks 62.

There is thus made available a bearing 30 forming an axial thrust bearing which can be handled, transported and mounted with a relatively small risk of the elements constituting it coming apart. In addition, the bearing 30 comprises in an integrated manner its own means for fastening to the locking shaft 16. This fastening involves screwing the axial portion 42 of the external ring 32 to the locking shaft 16 until the internal ring 34 bears against the leg 14a of the housing 14. In order to be able to transmit the clamping torque required between the thread 16b of the locking shaft 16 and the threads of the bore 44 once the bearing 30 has been placed in its final position on the said shaft, it is possible for example to deposit a drop of glue in order to immobilize the nut-forming external ring 32 on the thread 16b o f the shaft 16. As an alternative, or in an additional manner, it is also possible to machine the thread of the bore 44 such that it can be mounted with a high clamping torque on the thread 16b of the shaft 16.

Mounting the bearing 30 on the locking shaft 16 is particularly simple and takes place by simply screwing the external ring 32 until the internal ring 34 bears against the leg 14a of the housing 14.

Advantageously, the external surface of the axial portion 42 is formed in such a way as to obtain six identical faces which are parallel to the axis 30a of the bearing. A hexagonal nut head is thus formed. This makes it easier to screw the bearing 30 onto the locking shaft 16. The variant embodiment illustrated in Figure 5 , in which the identical elements bear the same references, differs from the above- described embodiment in that the annular portion 42 of the external ring 32 has a cylindrical outer surface, and in that two diametrically opposed holes 70 are provided on the radial portion 40 so as to allow the use of a pin spanner to clamp the external ring 32 on the locking shaft.

By virtue of the invention, there is provided a simple, compact bearing which is economic to manufacture and which is easy to mount, for example by simply screwing it onto a shaft of a position-locking system for a steering column.

Claims

1. Rolling bearing device for a system for locking a motor vehicle steering column in position of the type comprising a locking shaft and a lever for controlling the said shaft, the device comprising first and second rings (32, 34), at least one row of rolling elements

(36) which are arranged between raceways (40a, 46a) of the said rings, and a holding cage (38) for maintaining a uniform circumferential spacing between the rolling elements (36), one of the rings (32) having a radial portion (40) provided with the raceway (40a) and an axial portion (42) comprising means (44) for axially retaining the device on the locking shaft, characterized in that the holding cage (38) comprises means (60, 62) for axially retaining the first and second rings.

2. Device according to Claim 1 , in which the axial retention means comprise a threaded portion (44) which leads out at at least one end of the axial portion (42) and which is intended to engage with a corresponding threaded portion of the locking shaft.

3. Device according to Claim 1 or 2, in which the holding cage (38) has a radial portion (48) provided with pockets (54) for the rolling elements and internal (50) and external (52) axial portions each provided with means (60, 62) for axially retaining one of the rings.

4. Device according to any one of the preceding claims, in which the axial retention means comprise hooks (60, 62) extending radially in the direction of the rings.

5. Device according to any one of the preceding claims, in which one of the rings comprises means (42, 70) whereby the said ring can be driven to rotate by a clamping tool.

6. Device according to Claim 5, in which the driving means comprise flats formed on the outer surface of the axial portion (42).

7. Device according to Claim 5, in which the driving means comprise passage holes (70) formed on the radial portion (40).

8. System for locking a motor vehicle steering column in position that comprises a locking shaft, a lever for controlling the said shaft, a housing inside which the steering column is mounted, and a rolling bearing device according to any one of the preceding claims provided between the said housing and the locking shaft.

9. Motor vehicle steering column comprising a system according to Claim 8.