FR2816999A1 - Method for fitting bearing for steering column using an elastic packing ring to absorb radial and axial movements - Google Patents

Abstract

A method for fitting a bearing for a steering column has the outer bearing ring (11) gripped by an elastic packing ring (24) which grips the outer face of the ring as well as either edge, to absorb radial and axial movements. The packing ring is secured by an outer rigid clamping ring (4). The grip face of the packing ring has a ribbed surface texture to better grip the bearing ring and to provide additional flexibility. The fitting includes a space to allow for flexing of the packing ring. The fitting applies for both the bottom and top bearing of the steering column.

Description

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Steering column rolling bearing for motor vehicles. The present invention relates to the field of rolling bearings, in particular for steering columns of motor vehicles.

 The steering columns generally comprise a shaft, one end of which is secured to a drive wheel actuated by the driver of the vehicle and the other end of which is secured to mechanical members intended to ensure the angular positioning of the wheels of the vehicle, such as than a rack. The shaft of the steering column is mounted in a fixed tubular housing by means of two rolling bearings, generally with angular contact balls, mounted in opposition.

 The rack is attacked by a pinion linked directly to the steering column shaft or by means of an intermediate shaft and a universal joint.

 In a manner known per se, the steering column bearings comprise an outer ring, an inner ring, each ring comprising a toroidal raceway, balls being arranged between the two raceways in contact with the latter.

 A cage, generally made of molded synthetic material, holds the balls with regular circumferential spacing.

 One bearing is mounted towards the end of the column located on the side of the steering wheel and the other bearing is mounted at the other end of the column, on the side of the rack.

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 The outer rings of the bearings are secured to a tubular housing of the column secured to the chassis and the inner rings are mounted on the column shaft.

 In a steering column, the bearings must be able to support radial loads and axial loads, said loads arising from the loads exerted on the steering wheel and the reactions coming from the rack (and the cardan joint, if there is one).

 In addition, in this type of application where the bearings are very spaced in the axial direction and where the geometrical characteristics of the shaft and the tubular column housing are not always excellent, there may be misalignments between the two bearings which must then be able to absorb such defects while continuing to operate under satisfactory conditions and without affecting the service life of said bearings.

 Document FR-A-2 730 282 describes a steering column bearing comprising a casing in the form of a socket with a flange and a support, an outer ring in two parts, a solid inner ring, a row of balls, two elastic elements each between a part of the outer ring and the housing, and an element of limited axial resistance located inside the housing.

 The bearing structure is unsuitable for significant radial tightening or the transmission of significant axial forces, which in both cases would result in a modification of the preload in the bearing and of the contact angle between the balls and the raceways.

 The invention proposes a rolling bearing which overcomes the drawbacks of the prior art.

modifications importantes en ce qui concerne : - le jeu ou la précontrainte interne, - l'angle de contact, The invention provides an economical rolling bearing, capable of withstanding large axial and radial loads, a certain misalignment between the non-rotating housing and the rotating shaft, and a significant tightening on the shaft, without these elements causing

important modifications with regard to: - the play or the internal prestressing, - the contact angle,

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 which inevitably exist between the rolling elements and the raceways.

 The rolling bearing according to one aspect of the invention is in particular intended for a steering column of a motor vehicle, and is of the type comprising an outer ring, an inner ring, a row of rolling elements arranged between said rings, an elastic sleeve monoblock in axially and radially contact with one of said rings, said sleeve being, in the assembled state, axially and radially elastic, and an envelope for axially and radially maintaining the sleeve, an annular space being defined between said ring and the envelope, the sleeve being disposed in said space and leaving part of said space free to allow easy deformation of said sleeve.

 The free part of the space between envelope and ring allows a sleeve made of little or not compressible material such as rubber or an elastomer to deform. In the event that the free part is reduced to nothing, the sleeve would not be able to offer sufficient misalignment.

 In one embodiment of the invention, the envelope comprises an axial portion and at least one radial portion disposed at one end of the axial portion.

 Preferably, the envelope comprises two radial portions each disposed at one end of the axial portion. The free ends of said radial portions may have a diameter such that it prohibits any disassembly of the sleeve and of the ring with which the sleeve is in contact.

 In one embodiment of the invention, the sleeve comprises an axial portion and two radial portions each disposed at one end of the cylindrical portion.

 In one embodiment of the invention, a radial portion of the sleeve is disposed axially between a radial portion of the envelope and a radial surface of one of the rings. The sleeve provides both flexibility and axial retention between the casing and the ring with which it is in contact.

 In one embodiment of the invention, a portion

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 axial of the sleeve is arranged radially between an axial portion of the envelope and a cylindrical surface of one of the rings. The sleeve provides both flexibility and retention in the radial direction between the envelope and the ring with which it is in contact.

 In one embodiment of the invention, the sleeve is provided with a plurality of ribs coming into contact with one of the rings and / or with the envelope, the free part of said space being defined between the ribs. The sleeve can thus deform suitably, the material which composes it being able to fill the free part of said space between the ribs. The ribs can flex or crush as they deform.

 Advantageously, for a sleeve integral with the outer ring, the ribs will be provided on an outer surface of the axial portion of the sleeve for contact with the axial portion of the envelope.

 In one embodiment of the invention, the sleeve is provided with a plurality of protuberances in the form of studs or studs coming into contact with one of the rings and / or with the envelope.

The free part of said space is defined around the protuberances. The protrusions can flex or collapse while being deformed. The top of the protrusions is in contact with one of the rings and / or with the envelope.

 In one embodiment of the invention, the bearing comprises wires arranged in a torus mounted between at least one of the rings and the rolling elements and forming raceways.

Two wires can be provided per ring, on either side of the plane passing through the center of the rolling elements. A ring can have an annular shape with a U-section with an axial bottom and two radial branches.

 In another embodiment of the invention, the raceways are formed on a surface of each ring.

 Preferably, the envelope and the rings are made of thin sheet metal.

 The invention will be better understood on studying the detailed description of some embodiments taken as examples

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 in no way limiting and illustrated by the appended drawings, in which: FIG. 1 is a view in axial section of a rolling bearing according to a first embodiment of the invention; Figure 2 is a half view in axial section of the rolling bearing of Figure 1; Figure 3 is a half view in axial section of the rolling bearing of Figure 1 during a misalignment; Figure 4 is a half view in axial section of a rolling bearing according to a second embodiment of the invention; Figure 5 is a partial view in radial section of the rolling bearing of Figure 1; and FIG. 6 is a view in axial section of a rolling bearing according to a third embodiment of the invention.

 As can be seen in Figure 1, the rolling bearing 1 is disposed between a fixed housing 2 comprising a bore 3 and a front surface 4, and a rotating shaft 5. The housing 2 is provided with an annular groove 6 formed in the bore 3 and in which a circlip 7 is disposed 7. The rolling bearing 1 is disposed axially between the front surface 4 and the circlip 7. The rotating shaft 3 is provided with a cylindrical outer surface 8 and a toroidal outer surface 9 forming a shoulder.

 The rolling bearing 1 comprises an annular outer ring 10 of U-section, comprising an axial portion 11 and two radial portions 12 and 13 arranged at the opposite ends of the axial portion 11 and directed inwards. The radial portion 12 is slightly longer than the radial portion 13. The outer ring 10 is made from a sheet of thin sheet metal by cutting and stamping and / or rolling.

 The rolling bearing 1 comprises an annular inner ring 14 of U-section, comprising an axial portion 15 and two radial portions 16 and 17 arranged at the opposite ends of the axial portion 15 and directed outwards. The radial portions 16 and 17 are substantially the same length. The inner ring 14 is made from a sheet of thin sheet metal by cutting and stamping and / or rolling.

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 The outer ring 10 is completed by two wires 18 and 19 of circular section made of steel and of generally circular shape. The wires 18 and 19 form open rings, the ends of which are in contact. The wires 18 and 19 are in contact with the bore of the axial portion 11 of the outer ring 10. The wire 18 is in contact with the radial portion 12 and the wire 19 is in contact with the radial portion 13.

 Similarly, the inner ring 14 is completed by two wires 20 and 21 of circular section made of steel and of generally circular shape. The wires 20 and 21 form open rings, the ends of which are in contact. The wires 20 and 21 are in contact with the bore of the axial portion 15 of the inner ring 14. The wire 20 is in contact with the radial portion 16 and the wire 21 is in contact with the radial portion 17. The wires 18 , 19, 20 and 21 are concentric and the centers of their axial sections define a rectangle, even a square.

 The rolling bearing 1 comprises a row of rolling elements 22 disposed between the wires 18, 19, 20 and 21. The wires 18 and 19 define an external raceway and the wires 20 and 21 define an internal raceway. A cage 23 maintains the circumferential spacing between the rolling elements 22.

 The inner ring 14 is mounted directly on the rotating shaft 3, the axial portion 15 being in contact with the cylindrical outer surface 8 and a rounded area between the axial portion 15 and the radial portion 16 being in contact with the toroidal outer surface 9 of the rotating shaft 3.

 The rolling bearing 1 further comprises an elastic sleeve 24 made for example of elastomer or equivalent flexible material and integral with the outer ring 10. The sleeve 24 is a single piece and of annular shape with U-shaped section, comprising an axial portion 25 and two radial portions 26 and 27 disposed at opposite ends of the axial portion 25 and directed inward. The radial portions 26 and 27 are substantially the same length and the same thickness. The axial portion 25 is in contact with the outer surface of the axial portion 11 of the outer ring 10 and

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 surrounds it radially. The radial portions 26, 27 are in contact with the radial portions 12, 13 of the outer ring 10 and surround it axially.

 The outer surface of the axial portion 25 is provided with ribs 28 which are, in the embodiment shown, oriented axially. The ribs 28 leave the space between them free in the circumferential direction and can deform by being crushed under the action of a radial force and by filling at least partially the free space. The material of the sleeve 24 is flexible but not compressible and the free space gives the sleeve 24 a good deformation capacity which can be predetermined by varying the shape and the volume of the free space according to the desired characteristics.

 Alternatively, the ribs 28 can be oriented helically or circumferentially. As a variant, the sleeve 24 can be provided with studs or pins of circular shape, for example with a cross section which can be rectangular, trapezoidal, rounded or not, etc. The studs or studs define between them a free space in which they can deform.

 The rolling bearing 1 further comprises an envelope 29 made from a sheet of thin sheet metal by cutting and stamping and / or rolling. The casing 29 is in one piece and in contact with the sleeve 24. The casing 29 is of annular shape with U-section, comprising an axial portion 30 and two radial portions 31 and 32 arranged at the opposite ends of the axial portion 30 and directed towards the inside. The radial portions 31 and 32 are substantially the same length and the same thickness.

 The axial portion 30 is in contact with the outer surface - likely to include ribs, studs or spikes - of the axial portion 25 of the sleeve 24 and surrounds it radially. The radial portions 31, 32 are in contact with the radial portions 26, 27 of the sleeve 24 and surround them axially. The radial portion 31 is in contact with the front surface 4 of the housing 2, the radial portion 32 is in contact with the circlip 7 and the axial portion 30 is in contact with the bore 3 of the housing 2 in which it is adjusted, preferably with a tight fitting.

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 Thus, the rolling elements come into contact at four points with the wires 18 to 21 constituting the raceways. This type of bearing is particularly economical to manufacture and is entirely suitable for a steering column application which does not require high precision bearings but bearings capable of supporting radial and axial loads. In other words, the bearing comprises an outer casing 29, continuous in the circumferential direction and a deformable elastic sleeve 24, disposed between the outer casing 29 and the bearing itself. The inner ring 14 is mounted tight on the shaft 5. The casing 29 is mounted tight in the bore 3 of the housing 2. Additional axial immobilization elements, such as the front surface 4, the circlip 7 instead which could also provide a ring or a local deformation of the housing, allow to position and immobilize the bearing axially on the shaft and in the tubular housing to participate in the transmission of axial forces between shaft and housing through the bearing. The radial portions 31 and 32 of the casing 29 provide quality bearing surfaces for the axial locking elements. The elastic sleeve 24 and the casing 29 therefore fully participate in the transmission to the housing 2 of the forces exerted on the shaft 5.

 Figures 1 and 2 show an assembly without misalignment, that is to say in which the axis of rotation of the shaft and the axis of the housing are coincident.

 Figure 3 shows a rolling bearing 1 operating with misalignment. The axis of rotation of the shaft and the axis of the housing are no longer coincident and here make a certain angle alpha relative to each other. They could also be not confused but parallel. It can be seen that the elastic sleeve 24 has deformed to absorb the misalignment. The ribs 28 are slightly flattened on the side of the radial portion 26. The radial portion 26 is slightly compressed and flows radially in the free space between the portion 31 of the casing 29 and the portion 12 of the outer ring 10. The radial portion 27 tends to expand axially in the free space located between the radial portions 32 of the casing 29 and 13 of the

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 outer ring 10. The outer ring 10 has not deformed and continues to work while retaining its original geometric characteristics. The bearing characteristics of the bearing, for example the friction torque or the internal operating clearance, are preserved.

 In FIG. 4, an embodiment is shown in which a rolling bearing 33 comprises a sleeve 24 and an envelope 29 identical to those of FIGS. 1 to 3, massive outer 34 and inner 35 rings, provided respectively with a path inner and outer toroidal bearing 36, between which are arranged a row of rolling elements 22, for example balls, held by a cage 23. The outer ring 34 is provided with an outer axial surface 34a and two front surfaces radial 34b and 34c. The sleeve 24 is in contact with the axial 34a and radial 34b and 34c surfaces.

 In Figure 5, is illustrated in more detail the profile of the sleeve 24, the radial portion 25 has on its outer surface a plurality of ribs 28 oriented parallel to the axis of the rolling bearing 1. However, alternatively, one could provide helical or circumferential ribs. The ribs could also be arranged on an interior surface of the axial portion 25 or alternatively on both the interior and exterior surfaces.

 FIG. 6 illustrates an embodiment of a rolling bearing 38 close to that of FIGS. 1 to 3, except that the sleeve 39 and the casing 40 are associated with the inner ring 14 and no longer with the outer ring 10. In other words, the outer ring 10 is mounted directly in the bore 3 of the housing 2. The sleeve 39 is mounted in contact with the axial portion 15 and the radial portions 16 and 17 of the inner ring 14. The envelope 40 is mounted in contact with the axial part and the two radial parts of the sleeve 39. The envelope 40 is mounted on the shaft 5.

 Thanks to the invention, a steering column bearing is produced economically capable of tolerating misalignments, rotational lapses, offsets between the shaft.

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 and housing, while retaining its internal functional geometry.

 In other words, the defects of the shaft and of the housing are absorbed by deformations of the sleeve and have practically no influence on the rest of the elements of the rolling bearing.

 The rolling bearing is capable of transmitting high axial and radial forces, capable of being fitted tightly both in the column housing and on the shaft, and capable of damping vibrations.

 The transmission of axial forces between the rolling ring and the casing is done with great security, with vibration damping in the axial direction and does not require bonding, overmolding or immobilization of the sleeve by costly machining.

The sleeve is simply placed in the space between a bearing ring and the casing, said space having an annular shape with a U-section. The forces are simply transmitted by the radial portions of the sleeve which are pinched axially between the radial returns of the casing and a radial face of the bearing ring.

Claims (10)

 CLAIMS 1. Rolling bearing (1), in particular for a steering column of motor vehicles, characterized in that it comprises an outer ring (10), an inner ring (14), a row of rolling elements (22) disposed between said rings, a one-piece elastic sleeve (24) in axially and radially contact with one of said rings, said sleeve being, in the assembled state, axially and radially elastic, and an envelope (29) for axially and radially maintaining the sleeve , an annular space being defined between said ring and the envelope, the sleeve being disposed in said space and leaving free a part of said space to allow easy deformation of said sleeve.  2. Bearing according to claim 1, characterized in that the casing (29) comprises an axial portion (30) and at least one radial portion disposed at one end of the axial portion.  3. Bearing according to claim 1 or 2, characterized in that the sleeve (24) comprises an axial portion (25) and two radial portions (26,27) each disposed at one end of the cylindrical portion.  4. Bearing according to claim 3, characterized in that a radial portion of the sleeve is arranged axially between a radial portion of the casing and a radial surface of one of the rings.  5. Bearing according to claim 3 or 4, characterized in that an axial portion of the sleeve is arranged radially between an axial portion of the casing and a cylindrical surface of one of the rings.  6. Bearing according to any one of the preceding claims, characterized in that the sleeve (24) is provided with a plurality of ribs (28) coming into contact with one of the rings and / or with the casing, the part free of said space being defined between the ribs.  7. Bearing according to any one of the preceding claims, characterized in that the sleeve is provided with a <Desc / Clms Page number 12>  plurality of protrusions coming into contact with one of the rings and / or with the envelope.  8. Bearing according to any one of the preceding claims, characterized in that it comprises wires (18,19) arranged in a torus mounted between at least one of the rings and the rolling elements and forming raceways.  9. A bearing according to any one of claims 1 to 7, characterized in that the raceways are formed on a surface of the rings.  10. A bearing according to any one of the preceding claims, characterized in that the envelope and the rings are made of thin sheet metal.