Axial thrust bearing, especially for steering column

Abstract

Rolling bearing with axial thrust bearings, in particular for a steering column Rolling bearing (1), in particular for a steering column, comprising a first ring (2), a second ring (3) and at least one row of balls (4) arranged between said rings (2, 3), the second ring (3) comprising a casing (8) and at least one insert (9) arranged in the casing (8) to form a raceway of said second ring (3), and at least one prestressing element (11) mounted in the casing (8) and exerting an axial force on said insert (9). The first ring (2) is provided with a raceway (7) having a concave internal profile in cross section and at least one first stop surface (13a) extending, from a first axial end (e1) of the raceway (7), obliquely outwards in the direction of the second ring (3). Reference: Figure 2

Description

Title of the invention: Rolling bearing with axial thrust bearings, in particular for a steering column Technical field of the invention

[0001] The present invention relates to the field of rolling bearings and in particular those used in the steering columns of motor vehicles. State of the prior art

[0002] Steering columns generally comprise a shaft, one end of which is secured to a drive wheel operated 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 vehicle's wheels. The shaft of the steering column is rotatably mounted in a tubular housing by means of two rolling bearings.

[0003] A type of rolling bearing for a steering column comprises an inner ring, an outer ring and a row of balls arranged between raceways of said rings, at least one of the rings comprising a casing and inserts arranged in said casing to form raceways of said ring. This produces a rolling bearing with three or four contact points capable of operating under axial and / or radial loads. Generally, such a bearing also comprises an elastic prestressing element mounted inside the casing and bearing axially against one of the inserts so as to obtain operation with limited displacements.

[0004] The architecture of such a rolling bearing makes it possible to avoid the presence of free play in the bearing but does not completely limit the axial and radial movements between the rings even when adjusting the preload of the bearing after assembly.

[0005] The present invention therefore aims to remedy these drawbacks. Summary of the invention

[0006] The subject of the invention is a rolling bearing, in particular for a steering column, comprising a first ring, a second ring and at least one row of balls arranged between said rings, the second ring comprising an envelope, at least one added element arranged in the envelope to form a raceway for said second ring, and at least one prestressing element mounted in the envelope and exerting an axial force on said added element.

[0007] By “added element” is meant an element distinct from the envelope.

[0008] According to a general characteristic, the first ring is provided with a path of bearing having in cross section a concave internal profile and at least one first abutment surface extending, from a first axial end of the raceway, obliquely outwards towards the second ring.

[0009] Said abutment surface forms a break in slope relative to the rolling path in its connection zone with said path.

[0010] Said stop surface forms an axial stop making it possible to block the axial displacement of the row of balls. Thus, the relative axial and radial displacements between the first and second rings are limited. This also makes it possible to increase the axial rigidity of the bearing.

[0011] Advantageously, said stop surface of the first ring is of frustoconical shape.

[0012] In cross section, said stop surface of the first ring preferably extends perpendicularly to an oblique line which joins the first axial end of the raceway and the point of contact between said ball and the added element of the second ring which is axially on the side opposite said stop surface relative to said ball.

[0013] Advantageously, the first ring comprises an annular surface from which the raceway is formed, said stop surface connecting to said annular surface.

[0014] In one embodiment, said abutment surface connects to said annular surface via a chamfer.

[0015] Advantageously, in cross section, said stop surface extends obliquely, from the first axial end, on the side of the concave internal profile of the rolling track.

[0016] In one embodiment, the first ring comprises a second abutment surface extending, from a second axial end of the raceway opposite the first axial end, obliquely outwardly towards the second ring.

[0017] The second abutment surface of the first ring is preferably symmetrical to the first abutment surface with respect to a radial plane passing through the center of the balls.

[0018] In one embodiment, the second ring comprises two added elements which are arranged in the casing on either side of a radial plane passing through the center of the balls.

[0019] Advantageously, the two added elements of the second ring are identical.

[0020] In one embodiment, the first ring is the inner ring of the rolling bearing, and the second ring is the outer ring of the rolling bearing.

[0021] The invention also relates to a steering column comprising a housing, a shaft coaxial with said housing and at least one rolling bearing as defined above, mounted radially between the housing and the shaft. Brief description of the figures

[0022] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0023] [Fig-1] is an axial sectional view of a rolling bearing according to an exemplary embodiment;

[0024] [Fig.2] is a detail view of [Fig.l];

[0025] [Fig.3] is a detailed sectional view of a rolling bearing according to another example of realization; and

[0026] [Fig.4] is a detailed sectional view of a rolling bearing according to yet another exemplary embodiment. Detailed description of the invention

[0027] In [Fig.l], a rolling bearing is illustrated, designated by the reference numeral 1, comprising a first ring 2, a second ring 3, and a row of balls 4 arranged between said rings 2, 3. In this embodiment, the rolling bearing 1 comprises a cage 5 arranged radially between the rings 2, 3 to maintain a regular circumferential spacing between the balls 4. Alternatively, the rolling bearing 1 could be without a cage 5.

[0028] In this embodiment, the first ring 2 is the inner ring of the rolling bearing 1 and the second ring 3 is the outer ring of the rolling bearing 1.

[0029] The inner ring 2 comprises a cylindrical bore delimited axially by opposite radial front faces and an outer axial annular surface 6 from which is formed a toroidal circular groove having in cross section a concave internal profile capable of forming a raceway 7 for the balls 4, said groove being oriented radially outwards.

[0030] As will be described in more detail below, the inner ring 2 comprises stop surfaces 13a, 13b to limit the movement of the balls 4 axially along it.

[0031] The inner ring 2 is solid. The term “solid ring” means a ring whose shape is obtained by machining with chip removal (turning, grinding) from tubes, bars, forged and / or rolled blanks.

[0032] The outer ring 3 comprises an outer casing 8 and two separate inserts 9, 10 forming raceways of said ring 3 for the balls 4. The inserts 9, 10 are here in the form of two separate wires. The outer ring 3 also comprises a prestressing element 11 exerting an axial force on one of said inserts 9, 10. The inserts 9, 10 and the prestressing element 11 are mounted inside the casing 8.

[0033] The casing 8 can advantageously be manufactured by cutting and stamping a sheet of metal. The casing 8, of annular shape, comprises an external axial portion 12a extended, at each end, radially inwards by a radial portion 12b, 12c. The added elements 9, 10 are arranged in radial contact with the bore of the axial portion 12a and are arranged in the casing 8 on either side of a radial plane P passing through the center of the balls 4. The radial portion 12c has a radial dimension smaller than that of the radial portion 12b and also has a reduced thickness to be slightly curved in the direction of the balls 4 so as to come to bear against the added element 10 and axially prestress the bearing 1. The cage 5 is arranged radially between the free edge of the radial portion 12c of the casing 8 and the outer surface of the inner ring 2.

[0034] The casing 8 also comprises an inner axial portion 12d extending axially inwards a small diameter edge of the radial portion 12b. The axial portion 12d is provided for centering the prestressing element 11 inside the casing 8.

[0035] The prestressing element 11, of annular shape, is mounted axially in contact against the radial portion 12b of the casing 8 and the added element 9 and radially between the outer axial portions 12a and 12d inner while remaining at a distance from them. A radial surface of the prestressing element 11 is in axial contact with the inner face of the radial portion 12b and an opposite radial surface is in axial contact with the added element 9. The prestressing element 11 remains at a distance from the balls 4. The prestressing element 11 exerts a permanent axial force on the added element 9 which tends to prestress the balls 4 on the other added element 10 and on the groove of the inner ring 2.

[0036] The prestressing element 11 is advantageously formed from an elastic material, for example an elastomer such as nitrile rubber or polyurethane. In the illustrated embodiment, the prestressing element 11 is in the form of a torus with a square section. Alternatively, it could be possible to provide a prestressing element 11 having a different profile in cross section, for example circular.

[0037] The wires 9, 10 are in the form of open toroids and are mounted inside the casing 8 in direct contact with it. The balls 4 are arranged between the wires 9, 10 of the outer ring 3 which form raceways and the raceway 7 of the inner ring 2. This produces a rolling bearing 1 with three contact points. In the illustrated embodiment, the wires 9, 10 are identical so as to reduce manufacturing costs.

[0038] As illustrated more visibly in [Fig.2], the raceway 7 of the ring inner ring is provided with a first axial end el and a second axial end e2 which delimit the axial length of said raceway 7. The first and second axial ends el, e2 are offset radially on the side opposite the outer ring 3, i.e. inwards, relative to the outer axial annular surface 6. The first and second axial ends el, e2 are aligned considering the axial direction.

[0039] The first axial end el is located axially on the same side as the prestressing element 11 relative to the radial plane P passing through the center of the balls 4, and the second axial end e2 is located axially on the opposite side.

[0040] The inner ring 2 comprises a first annular abutment surface 13a of frustoconical shape which extends, from the first axial end el of the raceway 7, obliquely outwards in the direction of the outer ring 3 to the outer axial annular surface 6. The abutment surface 13a connects on one side to the outer axial annular surface 6 of the inner ring 2, and on the other side to the raceway 7. The abutment surface 13a thus extends between the first axial end el of the raceway 7 and the annular surface 6 of the inner ring 2. The connection of the abutment surface 13a to the annular surface 6 can be made by means of a chamfer.

[0041] In cross section, the abutment surface 13a extends obliquely, from the first axial end el, on the inner side of the concave internal profile of the raceway 7. In other words, the abutment surface 13a closes towards the inside of the arc of the raceway 7.

[0042] In cross-section, the abutment surface 13a intersects an oblique line d1 which joins the first axial end e1 of the raceway 7 of the inner ring 2 and the point of contact between said ball 4 and the axially opposite insert 10. The angle formed between the abutment surface 13a and this oblique line d1 may for example be between 25° and 85°. The inner ring 2 also comprises a second abutment surface 13b which extends from the second axial end e2 of the raceway 7, obliquely in the direction of the outer ring 3 to the outer axial annular surface 6. The abutment surface 13b connects on one side to the outer axial annular surface 6 of the inner ring 2, and on the other side to the raceway 7. The second abutment surface 13b thus extends between the second axial end e2 of the raceway 7 and the annular surface 6 of the first inner ring 2.The connection of the abutment surface 13b to the annular surface 6 can be made by means of a chamfer.

[0043] In cross section, the stop surface 13b extends obliquely, from the second axial end e2, on the inner side of the concave internal profile of the rolling track 7. In other words, the stop surface 13b closes towards the inside of the arc of the raceway 7.

[0044] In cross section, the abutment surface 13b intersects an oblique line d2 which joins the second axial end e2 of the raceway 7 of the inner ring 2 and the point of contact between said ball 4 and the axially opposite insert 9. The angle formed between the abutment surface 13b and this oblique line d2 can for example be between 25° and 85°.

[0045] The abutment surfaces 13a, 13b may be symmetrical with respect to the radial plane P passing through the center of the balls 4.

[0046] The surfaces 13a, 13b of the inner ring form axial stops making it possible to block the axial movement of the row of balls 4.

[0047] In this embodiment, the outer ring 3 comprises two elements 9, 10 inserted into the casing in the form of wires to form the raceways of the outer ring.

[0048] Alternatively, other designs of the outer ring may be provided.

[0049] For example, as illustrated in [Fig. 3], in which identical elements bear the same references, the outer ring 3 comprises an added element 9 in the form of a cup which delimits a rolling path for the balls 4.

[0050] In the embodiment illustrated in [Fig. 4], in which identical elements bear the same references, the outer ring 3 comprises a single added element 10 in the form of a cup which delimits a raceway for the balls 4, the casing 8 comprising an oblique extension 12d obliquely extending the inner axial portion 12d and delimiting a raceway for the balls 4. In this example, the prestressing element 11 is arranged axially between the radial portion 12c of the casing and the added element 10.

[0051] As indicated previously, in the illustrated embodiments, the first ring 2 of the bearing is the inner ring and the second ring 3 is the outer ring. Alternatively, it is possible to provide an inverted arrangement in which the first ring 2 is the outer ring and the second ring 3 is the inner ring. In this case, the raceway 7 and the abutment surface(s) 13a, 13b are formed on the bore of the outer ring which forms an inner surface of said ring.

Claims

Claims

1. Rolling bearing (1), in particular for a steering column, comprising a first ring (2), a second ring (3) and at least one row of balls (4) arranged between said rings (2, 3), the second ring (3) comprising a casing (8), at least one insert (9) arranged in the casing (8) to form a raceway of said second ring (3), and at least one prestressing element (11) mounted in the casing (8) and exerting an axial force on said insert (9), characterized in that the first ring (2) is provided with a raceway (7) having in cross section a concave internal profile and at least one first stop surface (13a) extending, from a first axial end (el) of the raceway (7), obliquely outwards in the direction of the second ring (3).

2. Bearing (1) according to claim 1, wherein said abutment surface (13a) of the first ring (2) is of frustoconical shape.

3. Bearing (1) according to one of claims 1 to 2, wherein the first ring (2) comprises an annular surface (6) from which the raceway (7) is formed, said abutment surface (13a) connecting to said annular surface (6).

4. Bearing (1) according to any one of claims 1 to 3, wherein, in cross section, said abutment surface (13a) extends obliquely, from the first axial end (el), on the inner side of the concave internal profile of the raceway (7).

5. Bearing (1) according to any one of claims 1 to 4, wherein the first ring (2) comprises a second abutment surface (13b) extending, from a second axial end (e2) of the raceway (7) opposite the first axial end (el), obliquely outwards towards the second ring (3).

6. Bearing (1) according to claim 5, wherein the second abutment surface (13b) of the first ring (2) is symmetrical to the first abutment surface (13a) with respect to a radial plane (P) passing through the center of the balls (4).

7. Bearing (1) according to any one of claims 1 to 6, in which the second ring (3) comprises two added elements (9, 10) which are arranged in the casing (8) on either side of a radial plane (P) passing through the center of the balls (4).

8. A bearing (1) according to any one of claims 1 to 7, wherein the first ring (2) is the inner ring of the rolling bearing (1), and the second ring (3) is the outer ring of the rolling bearing (1).

9. Steering column comprising a housing, a shaft coaxial with said housing and at least one rolling bearing (1) according to any one of claims 1 to 8, mounted radially between the housing and the shaft.

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