FR2798171A1 - Ball bearing unit for steering column of a motor vehicle has a washer to block the bearing on the shaft and an outer ring containing a series of inner circumferential projections - Google Patents

Abstract

The ball bearing unit (1) consists of an outer ring (4) and an inner ring (6) both providing rolling paths (5,7) for a series of balls (8) placed between them. A tolerance ring (9) is provided to ensure the liaison between the inner ring (6) and the shaft (3) of the steering column. A blocking washer (11) is provided to block the bearing on the shaft and the outer ring (4) contains a series of inner circumferential projections (13a), on its free end away from the rolling path (5), for the reception of a spring clip (14), which forms an axial stop for the blocking washer. A wavy washer (12) is provided to take up any axial play between the inner and outer rings of the bearing.

Description

Rolling bearing of steering column for motor vehicles. The present invention relates to the field of rolling bearings, especially for steering columns of motor vehicles.

The steering columns generally comprise a shaft whose end is integral with a driving wheel actuated by the driver of the vehicle and the other end is secured to mechanical members for ensuring the angular positioning of the vehicle wheels. The shaft of the steering column is mounted in a housing of fixed tubular shape via two rolling bearings, generally angular contact ball bearings, mounted in opposition.

These rolling bearings generally comprise an outer ring secured to the housing, an inner ring in contact with the shaft, each ring being provided with a toroidal race, and a row of rolling elements arranged between the two raceways and in contact with them. A cage can also be provided to maintain the regular circumferential spacing of the rolling elements. The cage is made, for example of molded synthetic material. Given the low speed of rotation of this type of bearing, the presence of a cage is not mandatory, the rolling elements can be provided substantially contiguous in the circumferential direction.

The bearing rings are made of pressed sheet metal and undergo a hardening heat treatment.

The outer rings of the rolling bearings are secured to the housing of the steering column and the inner rings are mounted on the column shaft via a so-called radially deformable tolerance ring, for example made of molded synthetic material. . The tolerance ring makes it possible to easily assemble the bearing on the shaft without initial clamping and then to be able to make the connection between the inner ring and the shaft, even when their respective sections have very different profiles, for example a inner ring having a form of revolution and a square section tree. The tolerance ring also makes it possible to compensate for deformations of the geometrical defects and dimensional dispersions of the rings and the shaft, and to transmit the axial prestressing force to the inner ring.

The tree may have a circular or polygonal cross section, for example square. The bore of the tolerance ring is adapted to the straight section of the shaft. The tolerance ring may be in the form of an elastic ring interrupted by a radial slot.

The assembly works with zero clearance due to an axial biasing force exerted on the tolerance rings by an axially elastic member which may be, for example, a spring, an elastic washer, etc.

The axial prestressing force can be exerted on the tolerance ring of only one of the two rolling bearings, the tolerance ring of the second rolling bearing being immobilized axially in the direction of this effort. The tolerance ring of the first rolling bearing can slide axially on the shaft, the axial force tends to bring axially closer to each other the inner rings of the two rolling bearings. This axial force can be exerted by an elastic washer, corrugated type or tongues with axial elasticity.

This compensates for the internal clearances of the bearings and ensures permanent contact without play and under preload between the rings and rolling elements of the rolling bearing.

Rolling bearings known for steering columns comprise an additional piece in the form of a lock washer for positioning the tolerance ring on the shaft of the steering column. The lock washer serves to close the entire rolling bearing and to lock it axially on the shaft while maintaining an axial preload on the tolerance ring in order to obtain a play without play of the rolling bearing.

Conventionally, the various parts of such a rolling bearing are only joined when they are mounted in the steering column device. There is therefore a risk of loss of elements during handling and assembly of the assembly in the steering column device. In addition, several different parts stocks must be managed.

For these various reasons, it is sought to form a releasable assembly comprising the rings, the rolling elements, the tolerance ring and the lock washer so as to assemble said assembly before mounting in the steering column device and thus to deliver rolling bearings ready to be mounted without the risk of losing parts.

Document FR 9705259 discloses a rolling bearing whose outer ring comprises a cylindrical portion provided with a plurality of bosses projecting radially inwards with respect to the bore of said cylindrical portion and arranged axially at the level of a cylindrical portion of the lock washer. The bosses define a diameter smaller than that of a radial flange of the lock washer and guarantee its retention in the axial direction.

However obtaining the bosses requires a recovery operation of the outer ring that complicates the manufacture and increases costs. The lock washer is forced back into the outer ring with elastic deformation during the passage of the boss or bosses and then resumes its original shape. It follows that the possibilities of radial interference, and therefore subsequent axial restraint, are severely limited under pain of being unable to assemble said parts. Small tearing material is, in addition, likely to occur during the re-entry force and pollute the interior of the bearing thereafter. After its introduction the lock washer can be placed in an inclined position relative to the bearing which is detrimental to its retention by the bosses.

The present invention aims to overcome these disadvantages.

Another object of the invention is to provide a rolling bearing forming a very compact non-removable assembly which can be mounted in a single operation in the steering column device.

The rolling bearing, according to the invention, is in particular intended for a steering column of a motor vehicle, and is of the type comprising an outer ring provided with a raceway, an inner ring provided with a raceway, a row of rolling elements arranged between the raceways of said rings, a tolerance ring ensuring the connection of the inner ring with the shaft of the steering column, and a lock washer for locking the bearing axially on the shaft. The outer ring comprises an axial retaining means of the lock washer. The outer ring is provided with a plurality of pins coming from a portion located towards the free end of said outer ring, axially opposite the raceway, said studs projecting radially inwardly to form an axial stop for an electric ring itself forming an axial stop for the lock washer. This ensures the axial retention of the elastic ring and the other elements in the outer ring.

Advantageously, the portion from which the spikes are derived is a rounded portion.

The pins may be formed from a surface of the rounded portion having a convex profile in axial section.

In one embodiment of the invention, the elastic ring is in contact with an outer surface of revolution of the lock washer, said surface having a convex profile in axial section.

Advantageously, said pins form for the elastic ring an axial abutment in the direction opposite to the raceway.

In one embodiment of the invention, the outer ring comprises additional pins axially offset relative to the first pins, the additional pins forming for the elastic ring an axial stop in the direction of the raceway.

Advantageously, the additional pins come from a rounded portion of said outer ring.

The additional pins are arranged axially at a distance from the first pins substantially equal to the thickness of the ring in the axial direction.

Advantageously, the pins and, if appropriate, the additional pins are circumferentially distributed.

Advantageously, the rolling bearing comprises an axial prestressing means, such as a spring washer axially disposed between the tolerance ring and the lock washer.

The elastic ring may be circular or polygonal section.

In one embodiment of the invention, the elastic ring is open.

The invention also relates to a method of manufacturing a rolling bearing as described above, in which the outer ring is formed by cutting and stamping a sheet blank, and then the outer ring comprising a portion axial which extends the opposite of the raceway, is punched locally the portion so as to discharge axially and radially of the material, the displaced material forming the first pins projecting radially inwardly relative to the bore of the axial portion.

Punching can be advantageously done on a surface having a convex profile in axial section.

An economical rolling bearing is obtained, the pins of the outer ring can be punched in masked time compared to other cutting and stamping operations. The mounting of the lock washer is carried out without radial interference with other elements and therefore without special effort, and without risk of permanent deformation or tearing of the metal particles that could come to pollute the bearing. The elastic ring is mounted last, and can be expected without disadvantage strong radial interference between the ring and the washer that holds. The ring offers to the washer that it retains a surface of contact and retaining almost continuous. A possible setting inclined position of the washer does not present a risk of disassembly.

In the free state, the elastic ring has a diameter greater than that of the bore in which it is mounted. The elastic ring is slightly preloaded resulting in great stability in space and time, further improved in case of double row of pins.

The invention will be better understood on studying the detailed description of some embodiments taken as non-limiting examples and illustrated by the accompanying drawings, in which FIG. 1 is a half-view in axial section of a rolling bearing according to a first embodiment of the invention; Figure 2 is a partial rear view of the outer ring of the rolling bearing of Figure 1; Figure 3 is a view similar to Figure 1 showing a rolling bearing according to a second embodiment of the invention; Figure 4 is a partial rear view of the outer ring of the rolling bearing of Figure 3; and Figures 5 and 6 are views in axial section of the outer ring of the rolling bearing of Figure 1 during manufacture. As can be seen in Figure 1, the rolling bearing 1 is disposed between a fixed housing 2 shown in fine lines and comprising a bore 2a and a front surface 2b, and a rotating shaft 3 also shown in fine lines.

The rolling bearing 1 comprises an outer ring 4 made of pressed sheet metal, defining a raceway 5, an inner ring 6, made of pressed sheet metal, defining a raceway 7, and a row of rolling elements 8, for example balls , arranged between the inner race 5 of the outer race 4 and the outer race 7 of the inner race 6.

The outer ring 4 comprises a cylindrical portion 4a extending from the raceway 5 and having a bore 4b, a rounded portion 4c extending from the free end of the cylindrical portion 4a, outwardly on an angle of 90 and having a convex surface 4d taken in axial section, and a radial flange 4e extending from the free end of the rounded portion 4c, outwardly and having a front surface 4f. The convex surface 4d is connected to the bore 4b and the front surface 4f.

The cylindrical portion 4a is in contact with the bore 2a of the housing 2 and the radial flange 4e is in contact with the front surface 2b of the housing 2 and serves as an axial positioning stop. The inner ring 6 comprises a cylindrical portion 6a fitted on the shaft 3 with a certain radial clearance and a toroidal portion 6b whose outer surface forms the path 7.

The rolling bearing 1 comprises an elastic tolerance ring 9 made of synthetic material, for example polyamide, and forming a ring interrupted by a radial slot 10. The radial slot 10 allows the tolerance ring 9 to adapt to variations diametrical dimensions of the shaft 3 and the inner ring 6, due to manufacturing tolerances and thus ensure elasticity of the connection between the inner ring 6 and the shaft 3. The tolerance ring 9 also makes it possible to compensate the housing coaxiality defects with respect to the shaft. The tolerance ring 9 comprises a bore 9a in contact with the shaft 3, a toroidal surface portion 9b of shape corresponding to the toroidal portion 6b of the inner ring 6 and in contact therewith, and the opposite of the toroidal surface 9b, a radial surface 9c.

The rolling bearing 1 also comprises a lock washer 11 comprising a radial portion 1 <B> 1 </ B> a, an oblique flange 11b extending from the radial portion 11a radially inwards and axially to the opposite of the tolerance ring 9, and a cylindrical portion 11c extending from the periphery of the radial portion 11a to the rolling elements 8 and arranged radially between the cylindrical portion 4a of the outer ring 4 and the tolerance ring 9 The junction between the radial portion 11a and the cylindrical portion 11c is provided by a rounded portion 11d having an outer surface 11e convex in axial section, on the opposite side to the rolling elements 8.

The oblique flange 11b which can be cut into tongues clamps on the shaft 3 which moves the lock washer 11 in the direction of the raceway 5 by sliding on the shaft 3 but prevents reverse axial movement by buttressing of the oblique flange 11b on the shaft 3. It is therefore possible, during assembly, to arrange the brake washer 11 in a determined axial position on the shaft 3 to apply axial prestressing to the inner ring 6 via the ring tolerance 9. The toroidal surface 9b of the tolerance ring 9 in contact with the inner ring 6 causes a wedge effect between the shaft 3 and the toroidal portion 6b of the inner ring 6 which ensures a satisfactory connection between the shaft 3 and the inner ring 6 and also prevents any inadvertent radial displacement of the tolerance ring 9 as the rolling bearing is not mounted on the shaft.

The rolling bearing 1 also comprises an elastic spring biasing washer 12, of corrugated type, arranged axially between the radial surface 9c of the tolerance ring 9 and the radial portion 11a of the lock washer 11, the spring washer 12 being surrounded radially. by the cylindrical portion 11c.

The outer ring 4 is provided with a row of pins 13 circumferentially regularly distributed, disposed on the convex surface 4d of the rounded portion 4c adjacent to the bore 4b. The pins 13 project radially inwards, their free radial ends 13a forming a fictitious circle of diameter much smaller than that of the bore 4b but slightly greater than the outer diameter of the brake washer 11. Axially, the pins 13 are are substantially at the same level as the oblique flange 11b of the lock washer 11.

The rolling bearing 1 comprises an elastic ring 14 open at a point of its circumference and of toroidal shape. The elastic ring 14 is disposed in the bore 4b of the cylindrical portion 4a and is retained axially in said bore by contact with the pins 13. In the mounted state, the elastic ring 14 has a smaller internal diameter than the outer diameter of the cylindrical portion 11c of the lock washer 11. The resilient ring 14 thus prevents axial movement disassembly of the lock washer 11 and holds together the rolling bearing parts. The elastic ring 14 can be made by cutting a wire which is then rolled on itself. A curing heat treatment may be provided to impart to said ring 14 the desired characteristics of hardness and elasticity. The elastic ring 14 has in the free state diametral dimensions such that it is slightly prestressed in the bore 4b, once set up in the said bore 4b.

Alternatively, the elastic ring 14 could be of polygonal section.

The contact between the lock washer 11 and the elastic ring 14 is done through the convex surface 11e of the rounded portion 11d, so that an axial force exerted by the lock washer 11 on the elastic ring 14 when it is in abutment against the pins 13 tends to open the elastic ring 14 by corner effect.

The rolling bearing 1 is assembled in the following way: the row of rolling elements 8 is placed on the path 5 of the outer ring 4, the inner ring 7 is brought into contact with the rolling elements 8, brings the tolerance ring 9 into contact with the inner ring 6, the elastic washer 12 is inserted axially and then the lock washer 11 into the outer ring 4, while exerting an axial bearing on the lock washer in the direction of the raceway 5, the elastic ring 14 is placed in the bore 4b by passing it through the row of pins 13, and the said axial support is released. The lock washer 11 presses on the elastic ring 14 which itself is retained by the row of pins 13. An axial thrust exerted by the lock washer 11 on the elastic ring 14 tends by wedge effect, to open the said ring and to increase the tightening on the outer ring 4, which increases the reliability and efficiency of the device and allows to handle safely the assembly thus formed without risk of accidental disassembly.

The embodiment illustrated in Figures 3 and 4 is similar to that of Figure 1 except that the outer ring 4 comprises a row of additional pins 15 projecting radially inwardly relative to the bore 4b and arranged axially between the pins 13 and the rolling elements 8, substantially at the level of the cylindrical portion 11c of the lock washer 11 and the spring washer 12. An axial space serving as a housing for the elastic ring 14 is left between the pins 13 and the additional pins 15 which thus serve to prevent any axial displacement of the ring 14 towards the rolling elements 8 and more particularly a possible crossing of the ring 14. It can be seen in FIG. 3 that two additional pins 15 are arranged on one side and the other of a pin 13. Of course other arrangements may be envisaged: an additional pin 15 by pin 13, a pin additional 15 for two pins 13, etc.

As can be seen in Figures 5 and 6, the pins 13 of an outer ring 4 are obtained by punching. The outer ring 4 during manufacture is arranged in a matrix of which a portion 16 matches the shape of the outer surface of the cylindrical portion 4a and the surface of the radial flange 4e opposite the front surface 4f at least locally. A punching tool 17 is axially supported on the front surface 4f at least locally.

The punching tool 17 comprises a number of punches 18 axially movable relative to said punching tool, each punch being disposed in a hole 19 of said tool.

Each punch is moved axially towards the raceway 5 and comes into contact with the convex surface 4d of the rounded portion 4c. The displacement of the punches 18 being continued, causes the plastic deformation of the rounded portion 4c by thinning it near the radial flange 4e, the displaced material being found at the junction between the rounded portion 4c and the cylindrical portion 4a and thus forming In other words, axial punching is carried out which causes a discharge of axial and radial material inwards.

The additional pins 15 may similarly be formed using a tool, not shown, slightly closer to the axis of the outer ring 4 and moving material of the outer ring 4 from an area of the rounded portion 4c close of the cylindrical portion 4a axially towards the rolling elements 8 in the bore 4a.

Advantageously, the punching operation can be done in masked time with other forming operations of the outer ring 4.

Thanks to the invention, a rolling bearing is obtained compact axially and radially and can be handled by an operator before final installation without risk of losing parts. As the elastic ring is mounted last after the lock washer, it can provide a significant diametral interference between said elastic ring and the lock washer, resulting in an improvement in the axial retention.

The elastic ring is a retaining member for the lock washer acting on its entire circumference. It will therefore be understood that it remains effective even if the lock washer tends to incline relative to the axis of the bearing.

Finally, the zones of contact between the elastic ring and the lock washer being designed so that if the lock washer exerts an axial force on the elastic ring, it abuts against the pins and said axial force tends to opening the ring and increasing the tightening of said elastic ring in the bore of the outer ring of the groove, which enhances the reliability and effectiveness of the retainer.

Claims (12)

1. Rolling bearing (1), especially for steering column of motor vehicles, of the type comprising an outer ring (4) provided with a raceway, an inner ring (6) provided with a raceway, a row of rolling elements (8) arranged between the races of said rings, a tolerance ring (9) connecting the inner ring with the steering column shaft, and a lock washer (11) for locking the bearing axially on the shaft, characterized in that the outer ring (4) is provided with a plurality of pins coming from a portion located towards the free end of said outer ring, axially opposite the raceway, said pins projecting radially inwardly to form an axial stop for a ring (14) elastic itself forming axial stop for the lock washer. 2. Bearing according to claim 1, characterized in that the portion from which the pins are derived is a rounded portion. 3. Bearing according to claim 2, characterized in that the spikes are formed from a surface of the rounded portion having a convex profile in axial section. 4. Bearing according to any one of the preceding claims, characterized in that the ring (14) elastic is in contact with an outer surface of revolution of the lock washer, said surface having a convex profile in axial section. 5. Bearing according to any one of the preceding claims, characterized in that said pins form for the elastic ring an axial stop in the direction opposite to the raceway. 6. Bearing according to any one of the preceding claims, characterized in that the outer ring (4) comprises additional pins axially offset relative to the first pins, the additional pins forming for the elastic ring an axial stop in the direction of the raceway. 7. Bearing according to claim 6, characterized in that the additional pins are derived from a rounded portion of said outer ring. 8. Bearing according to claim 6 or 7, characterized in that the additional pins are arranged axially at a distance from the first pins substantially equal to the thickness of the ring in the axial direction. 9. Bearing according to any one of the preceding claims, characterized in that the ring (14) elastic is circular section. 10. Bearing according to any one of the preceding claims, characterized in that the ring (14) elastic is polygonal section. 11. Bearing according to any one of the preceding claims, characterized in that the elastic ring is open. 12. A method of manufacturing a rolling bearing according to any one of the preceding claims, wherein the outer ring is formed by cutting and stamping a sheet blank, and the outer ring comprises an axial portion which extends it. in contrast to the raceway, said portion is punched locally so as to axially and radially discharge the material, the displaced material forming the first pins projecting radially inwardly relative to the bore of the axial portion. .