FR2780117A1 - Roller bearing for steering column of vehicle - Google Patents

Abstract

The bearing has an outer ring (29) and an inner ring (33) and a row of roller bodies (35) which are located between an inner track of the outer ring and an outer track of an inner ring. A cage is provided for holding the roller bodies in place between the two rings. An equalization ring (37) is provided which is in contact with the inner and outer rings. The cage has means for securing the equalization ring.

Description

Rolling bearing.

  The invention relates to the field of rolling bearings, in

  especially those used in the steering columns.

  Generally, steering column roller bearings have an outer ring, an inner ring, each ring having a toroidal raceway, and a row of balls

  arranged between the two raceways in contact with the latter.

  Generally used for the manufacture of such bearings, stamped sheet metal rings, said rings then being heat treated

  to give them the necessary hardness.

  A cage is arranged in the bearing to maintain a regular circumferential space between the balls. The cage is usually

  made of molded synthetic material.

  The steering columns are generally equipped with a pair of angular contact bearings mounted in opposition and operating at zero clearance thanks to an axial prestressing force exerted on the inner rings by an axially elastic member, spring, elastic washer, etc. The outer bearing rings are secured to the housing of the steering column and the inner rings are mounted on the column shaft by means of a tolerance ring which ensures easy mounting of the bearing on the shaft without initial tightening and then realize the connection between the inner ring and the shaft, even when the sections of the shaft and the inner ring have a very different profile. For example, the tolerance ring can allow, by suitable shapes, to mount an inner ring having a shape of revolution on a shaft with a square section. The deformation of the tolerance ring makes it possible to compensate for geometric defects and dimensional dispersions of the inner ring and the shaft. Finally, the tolerance ring allows the axial stressing force to be transmitted to the inner ring. The tree may have, depending on the case, a

  circular or polygonal cross section, for example square.

  The tolerance ring is in the form of an elastic ring opened at a point on its circumference by a slot extending axially and radially over the entire thickness of the ring, which

  provides the required radial elasticity.

  The tolerance ring is manufactured by molding a synthetic material such as a polyamide which can be loaded with elements capable of improving its mechanical characteristics, for example glass fibers. The bore of the tolerance ring is of circular or polygonal section, square for example, depending on the section of the shaft. In the free state, the tolerance ring has a radial clearance

  relatively large compared to the tree.

  The bearings, fitted with their tolerance ring, are placed on the shaft and in their housing. The axial prestressing force is then exerted on the tolerance ring by means of one or more elastic members which exert on said tolerance ring a force tending to bring the inner and outer rings axially one from the other. We thus compensate for the internal clearances of the bearings by ensuring permanent contact without clearance and under preload between the rings of the

bearing and balls.

  Furthermore, by wedge effect between the bore of the inner ring and the conical outer shape of the tolerance ring, the latter tightens on the shaft thus ensuring a connection without play between these elements. One of the problems to be solved in this type of rolling bearing is to ensure that the assembly constituted by the bearing proper cannot be dismantled, that is to say the inner and outer rings, the balls

  and the cage, and the tolerance ring.

  Document DE-A-38 08 556 proposes a steering column bearing in which non-demountability is ensured by means of a tolerance ring provided with an axial extension provided with hooks

  coming to cooperate with a radial portion of the outer ring.

  The main drawback of such a bearing is that part of the tolerance ring must pass between the inner ring of the bearing and the steering column shaft, which increases

  the axial size of this assembly.

  The object of the present invention is to propose another means

  ensuring the non-dismantling of the rolling bearing.

  The present invention also relates to a rolling bearing of small radial size, suitable for steering columns. The steering column rolling bearing device according to the invention is of the type comprising an outer ring, an inner ring, a row of rolling elements arranged between an inner race of the outer ring and a race outside of the inner ring, a rolling element holding cage mounted between said two rings and provided with cells in which the rolling elements are arranged, and an annular tolerance ring in contact with an inner surface of revolution of the inner ring and with the periphery of the steering column shaft. The cage

  comprises means for axial retention of the tolerance ring.

  In one embodiment of the invention, the means of

  axial retainers are active before mounting in the steering column.

  Advantageously, the cage comprises at least one protuberance directed radially inwards. The protuberance can have the form

  a continuous bead or a plurality of hooks.

  In one embodiment of the invention, the tolerance ring comprises at least one retaining surface arranged on its periphery and

  able to cooperate with the axial retaining means.

  In one embodiment of the invention, the axial retaining means are able to cooperate with a lock washer

  immobilization of the bearing on the shaft, and with the tolerance ring.

  In another embodiment of the invention, the axial retaining means are able to cooperate only with a locking washer for immobilizing the bearing on the shaft, the tolerance ring being retained by means of the washer- brake. A washer of

  prestress can be placed between the tolerance ring and the washer-

  brake. Advantageously, the cage comprises means for axially retaining the outer ring. There is thus a non-removable rolling bearing before its final installation between a steering column housing and a shaft and therefore no longer risking an untimely separation of its components, while retaining a very small radial size and an economical construction, in the extent that the inner and outer rings remain unchanged, while no additional parts

is necessary.

  The invention will be better understood and other advantages

  will appear on reading the detailed description of some modes of

  embodiment taken by way of nonlimiting examples and illustrated by the appended drawings, in which: FIG. I is a view in axial section of a steering column shaft disposed in its housing, according to the prior art; Figure 2 is a sectional view along II-II of Figure 4 of a rolling bearing according to the invention, during assembly; Figure 3, similar to Figure 2, shows the rolling bearing in the assembled state; Figure 4 is a radial sectional view along line IV-IV of Figure 3; and Figures 5 and 6 are views similar to Figure 3, showing

  other embodiments of the invention.

  As can be seen in Figure 1, a steering column shaft i is disposed in a housing 2 and fixed in rotation therein by two identical bearings 3 and 4. Only bearing 4 will be described in

what follows.

  The bearing 4 comprises an outer ring 5 provided with an inner toroidal raceway 6. The outer ring 5 is extended by a cylindrical portion 7 whose free end is folded outwardly forming a radial rim 8. The portion cylindrical 7 is provided with several inwardly projecting protrusions 9 obtained

  by deforming said cylindrical portion 7.

  The bearing 4 also comprises an inner ring 10 of toroidal shape whose outer surface forms a raceway 1 1. Between the raceways 6 and 11, are arranged a row of rolling elements 12, for example balls. A cage 13, made of synthetic material, makes it possible to maintain a

  regular circumferential spacing between the rolling elements 12.

  A tolerance ring 14, made of synthetic material, possibly added with a filler improving its mechanical properties, for example fiberglass, is disposed in contact with the periphery 1a of the shaft 1. The tolerance ring 14 comprises an inner surface 15 of shape adapted to the periphery 1a of the shaft 1, an outer surface 16 of cylindrical revolution, a bearing surface 17 disposed on the side of the rolling elements 12 and of a shape adapted to the inner surface 18 of the ring inner 10 which has a meridian cross-section in the form of an arc of a circle whose convexity is directed towards the shaft, and a radial surface 19 opposite the bearing surface 17. The tolerance ring 14 thus forms a ring which is opened by a slot 20 in order to allow its adaptation to the periphery 1a of the shaft 1 and to the internal surface 18 of the internal ring 10. The tolerance ring is therefore an int ermediary providing the interface and the link between the

  inner ring 10 and the shaft 1 on which said ring is mounted.

  An annular elastic washer 21 is disposed on the periphery 1a of the shaft 1 in contact with the radial surface 19 of the tolerance ring 14. The elastic washer 21 has circumferential undulations so as to have an axial elasticity allowing it

  press on the tolerance ring 14.

  A lock washer 22 is disposed between the shaft 1 and the cylindrical portion 7 of the outer ring 4. The lock washer 22 comprises a

  radial portion 23 in contact with the elastic washer 21 on the side thereof

  ci opposite to the tolerance ring 14, the radial portion 23 extending inwards by an oblique portion 24 cut into teeth or tongues, directed opposite the elastic washer 21 and of diameter, in the free state, slightly lower than that of the shaft 1 to form an automatic locking means allowing the lock washer 22 to move in the direction of the elastic washer 21 but preventing any disassembly movement in the opposite direction, by bracing effect. The radial portion 23 is extended on the side opposite to the oblique portion 24 by a cylindrical portion 25 extending between the elastic washer 21 and the protrusions 9 of the cylindrical portion 7 of the outer ring 4. The cylindrical portion 25 ends in a rim 26 radial directed outwards and whose periphery is of diameter slightly greater than the fictitious circle circumscribed by the protrusions 9 to avoid any

  separation of the outer ring 4 and the lock washer 22.

  The radial rim 8 of the outer ring 4 is designed to come into contact with a front surface 27 of the housing 2. The outer ring 5 is thus locked axially in one direction, while it is locked in the other direction by the washer. -brake 22 whose teeth of the oblique portion 24 come into hooking contact on the periphery 1a of the shaft 1. The prestressing of the outer 5 and inner 10 rings of the bearing 4

  is provided by the elastic washer 21 and the tolerance ring 14.

  Although such a bearing is entirely satisfactory from a technical point of view, it nevertheless requires an additional operation to be carried out during the manufacture of the outer ring, namely the formation of the radial protrusions 9. On the other hand, the presence of the washer -brake is mandatory. As seen in Figures 2 to 4, the rolling bearing 28 comprises an outer ring 29 provided with an inner toroidal raceway 30. The outer ring 29 is extended by a cylindrical portion 31 whose free end is folded outwardly forming a radial rim 32. The bearing 28 also includes an inner ring 33 of toroidal shape whose outer surface forms a raceway 34. Between the raceways 30 and 34, are arranged a row of elements rollers 35, for example balls. The raceway 30 is disposed on one side of a radial plane passing through the center of the rolling elements 35, while the raceway 34 is disposed on the other side of said plane. A cage 36, made of synthetic material, makes it possible to maintain regular circumferential spacing

between the rolling elements 35.

  A tolerance ring 37, made of synthetic material, optionally added with a filler improving its mechanical properties, for example fiberglass, is disposed in contact with the periphery of the shaft, not shown. The tolerance ring 37 includes an inner surface 38 of a shape adapted to the periphery of the shaft, an outer surface 39 of cylindrical revolution, a bearing surface 40 disposed on the side of the rolling elements 35 and of a shape adapted to the inner surface 41 of the inner ring 33 which has an axial cross section in the form of an arc of a circle whose convexity is directed towards the shaft, and a radial surface 42 opposite the bearing surface 40. The tolerance ring 37 forms a ring which is opened by a slot 43 in order to allow its adaptation to the periphery of the tree and to the surface

  inner 41 of inner ring 33.

  The cage 36 includes an annular part 44 disposed between the outer 29 and inner 33 rings on the side of the raceway 30, a dimpled part, not visible in the figures, hidden by the rolling elements 35 arranged in these dimples, and another part annular 45 disposed on the side opposite to the first annular part 44 and surrounded by the cylindrical part 31 of the outer ring 29. The annular part 45 extends axially beyond the inner ring 33 and comprises a bore 46 which extends axially opposite the rolling elements 35 by a chamfer 47. A chamfer 47 is provided with a plurality of radial protrusions 48 circumferentially regularly spaced and projecting radially inwards. The radial protrusions 48 are provided with an entry surface 49 arranged on the side opposite to the rolling elements 35 and a blocking surface 50 arranged on the side of the rolling elements 35, the entry surfaces 49 and blocking 50 being oblique. Between the external cylindrical surface 39 of the tolerance ring 37 and the bearing surface 40, there is provided a continuous bead 51 projecting radially outwards and of external diameter such that it interferes with the protrusions 48 of the cage 36 The bead 51 is formed on one side by an extension of the concave surface 40, and on the other side by an oblique surface 52 connecting to the outer cylindrical surface 39. The locking surface 50 of the cage 36 and the oblique surface 52 of the tolerance ring 37 have substantially equal slopes so as to be able to cooperate with each other and ensure the axial locking of the tolerance ring 37 relative to the cage 36. Advantageously, hooks 44a oriented radially outwards and located at the end of the first annular part 44 of the cage 36 ensure the axial retention of the outer ring by the cage. In FIG. 2, the tolerance ring 37 is not yet definitively mounted with axial retention on the cage 36. The tolerance ring 37 is therefore presented in the bore of the cylindrical part 31 of the outer ring 29 by centering it on the axis of the rolling bearing 28, then it is pushed axially in the direction of the rolling elements 35. The bead 51 thus comes into contact through the concave surface 40 with the entry surface 49 of the protrusions 48 of the cage 36, this which causes a tightening of the tolerance ring 37 thanks to its slot 43. Then the bead 51 crosses the protrusions 48 and the oblique surface 52 is in contact with the locking surface 50, which causes the axial retention of the ring tolerance 37 with respect to the cage 36 and consequently with the rolling elements 35 and the inner ring 33. Advantageously, the hooks 44a oriented radially outwards and located at the end of the first part ie annular 44 of the cage 36 ensure the axial retention of the outer ring by the cage. The rolling bearing is then in the state illustrated in Figure 3 o the cage provides axial retention and

  the non-demountability of all the elements.

  It can therefore be seen that it is possible to produce a rolling bearing of very small radial size, which cannot be dismantled even during its transport and its handling with a view to its installation in a steering column, and this independently of a locking washer, which allows to consider providing a steering column shaft with two rolling bearings, one of which would not have a lock washer and

  preload or lower costs.

  The embodiment illustrated in FIG. 5 is similar to that of FIGS. 2 to 4, except that the cage 36 comprises an additional cylindrical part 53 extending beyond the annular part 45 opposite the rolling elements 35 radially close to the bore of the cylindrical part 31 of the outer ring 29. At the end of the cylindrical part 53, are arranged a plurality of protrusions 54 directed radially inwards, circumferentially regularly distributed and forming hooks. These protrusions 54 are provided to cooperate with the radial rim 26 of a lock washer 22 of the

  type illustrated in FIG. 1 which is arranged in the rolling bearing 28.

  An annular elastic washer 21 is disposed axially between the lock washer 22 and the rear radial surface 42 of the tolerance ring 37. In this way, thanks to the cage 36, not only is the axial retention, before assembly, of the ring tolerance 37, but also the axial retention, before assembly, of the lock washer and consequently of the washer

  elastic, without adding any additional parts.

  The embodiment illustrated in FIG. 6 is similar to that of FIG. 5, except that the cage 36 is devoid of the protrusions 48 of FIGS. 2 and 3, and that the tolerance ring 37 is devoid of bead 51, the axial retention of the tolerance ring 37 being ensured only by means of the lock washer 22 and the elastic washer 21 by cooperation between the radial rim 26 and the protrusions 54. The outer cylindrical surface 39 of the tolerance ring 37 connects directly to the concave surface 40. A cage 36 of simplified shape is thus used. The mounting of the tolerance ring 37 is slightly easier insofar as the tolerance ring 37 does not have to cross the protrusions 48 and can therefore be disposed without thrust, the axial retention being nevertheless ensured by means of

  the spring washer and the lock washer.

  Thanks to the invention, there is a cage for retaining the rolling elements of a rolling bearing capable of ensuring the axial retention of other elements of the rolling bearing, in particular a tolerance ring, and possibly d '' a lock washer and an elastic washer, without increasing the radial size and without

increased number of pieces.

O10

Claims (10)

  1. Rolling bearing device (28) of a steering column, of the type comprising an outer ring (29), an inner ring (33), a row of rolling elements (35) arranged between an inner raceway of the outer ring and an outer raceway of the inner ring, a cage (36) for holding the rolling elements mounted between said two rings and provided with cells in which the rolling elements are arranged, and an annular tolerance ring (37 ) in contact with an inner surface of revolution of the inner ring and with the periphery of the steering column shaft, characterized in that the cage comprises axial retaining means of the tolerance ring.   2. Device according to claim 1, characterized in that the said axial retaining means are active before mounting in the steering column.   3. Device according to claim 1 or 2, characterized in that the cage comprises at least one protuberance (48) directed radially towards the inside.   4. Device according to claim 3, characterized in that   the protuberance has the shape of a continuous bead.   5. Device according to claim 3, characterized in that   the protuberance has the form of a plurality of hooks.   6. Device according to any one of claims   above, characterized in that the tolerance ring comprises at least one retaining surface (52) arranged on its periphery and capable of   cooperate with the axial retaining means.   7. Device according to any one of the claims   above, characterized in that the axial retaining means are able to cooperate with a bearing immobilizing lock washer   on the shaft, and with the tolerance ring.   8. Device according to any one of claims 1 to 5,   characterized by the fact that the axial retaining means are able to cooperate only with a locking washer for immobilizing the bearing on the shaft, the tolerance ring being retained by   through the lock washer.   9. Device according to claim 7 or 8, characterized in that it comprises a prestressing washer arranged between the ring tolerance and the lock washer.   10. Device according to any one of the claims   previous, characterized in that the cage includes means (44a)   axial retaining ring.