Rolling bearing with axial stop, in particular for steering column
The rolling bearing for steering columns addresses axial and radial movement limitations by incorporating oblique thrust surfaces and a prestressing element, enhancing stiffness and precision.
Patent Information
- Application Number
- JP2025034708
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-03-13
- Filing Date
- 2025-03-05
- Publication Date
- 2025-09-29
AI Technical Summary
Existing rolling bearings for steering columns do not effectively limit axial and radial movement between rings, despite adjustments for preload, leading to potential play and reduced stiffness.
A rolling bearing design featuring a first ring with oblique thrust surfaces and a prestressing element to apply axial force, combined with insert elements and a cage to maintain ball spacing, preventing axial movement and enhancing stiffness.
The design effectively limits axial and radial movement, increasing the bearing's stiffness and ensuring precise angular positioning of vehicle wheels.
Smart Images
Figure 2025141847000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to the field of rolling bearings, in particular those used in steering columns of motor vehicles. [Background technology]
[0002] A steering column generally comprises a shaft, one end of which is fixedly attached to the drive steering wheel operated by the vehicle driver and the other end of which is fixedly attached to a mechanical member whose purpose is to ensure the angular positioning of the vehicle's wheels, the shaft of the steering column being rotatably mounted within a tubular housing via two rolling bearings.
[0003] One type of rolling bearing for a steering column includes an inner ring, an outer ring, and a row of balls disposed between the bearing races of the rings, with at least one of the rings including a casing and an insert element disposed within the casing to form the bearing race of the ring. This creates a rolling bearing with three or four contact points that can function under axial and / or radial loads. Typically, such bearings also include an elastic prestressing element mounted inside the casing and axially abutting and supporting one of the insert elements to function with limited movement.
[0004] Such a rolling bearing design makes it possible to avoid the presence of play in the bearing, but does not completely limit axial and radial movement between the rings, even when the bearing preload is adjusted after installation. Summary of the Invention [Problem to be solved by the invention]
[0005] The object of the present invention is therefore to remedy these drawbacks. [Means for solving the problem]
[0006] The subject of the present 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 a casing, at least one insert element arranged in the casing to form a bearing race of the second ring, and at least one prestressing element mounted in the casing and applying an axial force to the insert element.
[0007] An "insertion element" is an element separate from the casing.
[0008] According to a general feature, the first ring is provided in a straight section with a bearing race having a concave inner profile and at least one first thrust surface extending from a first axial end of the bearing race obliquely outwardly towards the second ring.
[0009] The thrust surface forms a slope change with respect to the bearing race in the region of its connection to the race.
[0010] The thrust surfaces form axial restraints that allow the row of balls to be prevented from moving axially, thus limiting the relative axial and radial movement between the first and second rings, which also allows for increased axial stiffness of the bearing.
[0011] Advantageously, said thrust surface of the first ring is frusto-conical in shape.
[0012] In the straight portion, the thrust surface of the first ring preferably extends perpendicular to an oblique line connecting the first axial end of the bearing race and the point of contact between the ball and the insert element of the second ring, which is axially opposite the thrust surface with respect to the ball.
[0013] Advantageously, the first ring includes an annular surface from which a bearing race is formed, said thrust surface being connected to said annular surface.
[0014] In one embodiment, the thrust surface is connected to the annular surface via a chamfered surface.
[0015] Advantageously, in the straight section, said thrust surface extends obliquely from the first axial end, from the side of the concave inner profile of the bearing race.
[0016] In some embodiments, the first ring includes a second thrust surface extending from a second axial end of the bearing race opposite the first axial end, obliquely outwardly toward the second ring.
[0017] The second thrust surface of the first ring is preferably symmetrical to the first thrust surface about a radial plane passing through the centre of the ball.
[0018] In one embodiment, the second ring includes two insert elements within the casing that are positioned on either side of a radial plane that passes through the center of the ball.
[0019] Advantageously, the two insert 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 present invention also relates to a steering column comprising a housing, a shaft coaxial with said housing, and at least one rolling bearing as defined in the preceding paragraph mounted radially between the housing and the shaft.
[0022] Further objects, features and advantages of the present invention will appear on reading the following description, given purely by way of non-limiting example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]
[0023] [Figure 1] 1 is an axial cross-sectional view of a rolling bearing according to an exemplary embodiment; [Figure 2] FIG. 2 is a detailed view from FIG. 1. [Figure 3] FIG. 10 is a detailed cross-sectional view of a rolling bearing according to another exemplary embodiment. [Figure 4] FIG. 10 is a detailed cross-sectional view of a rolling bearing according to yet another exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0024] 1 shows a rolling bearing, designated by reference numeral 1, including a first ring 2, a second ring 3, and a row of balls 4 disposed between said rings 2, 3. In this embodiment, the rolling bearing 1 includes a cage 5 disposed radially between the rings 2, 3 to maintain uniform circumferential spacing between the balls 4. Alternatively, the rolling bearing 1 may not have a cage 5.
[0025] 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 .
[0026] The inner ring 2 comprises, in its straight portion, a cylindrical hole axially delimited by opposing radial front faces and an outer axial annular face 6, in which is formed a toroidal circular groove having a concave inner profile suitable for forming a bearing race 7 for the balls 4, said groove being oriented radially outwards.
[0027] As will be described in more detail below, the inner ring 2 includes thrust surfaces 13a, 13b for limiting the movement of the balls 4 axially therethrough.
[0028] The inner ring 2 is solid. By "solid ring" is meant a ring whose shape is obtained by machining involving the removal of small pieces (turning, grinding) from a tube, a bar, a forged blank and / or a rolled blank.
[0029] The outer ring 3 comprises an outer casing 8 and two separate insert elements 9, 10 which form the bearing races of said ring 3 for the balls 4. The insert elements 9, 10 here take the form of two separate beads. The outer ring 3 also comprises a prestressing element 11 which applies an axial force to one of the insert elements 9, 10. The insert elements 9, 10 and the prestressing element 11 are mounted inside the casing 8.
[0030] Advantageously, the casing 8 can be cut from sheet metal and manufactured by deep drawing. The annular casing 8 includes an outer axial portion 12a, which is extended radially inward at each end by radial portions 12b, 12c. The insert elements 9, 10 are arranged in the casing 8 in radial contact with the bore of the axial portion 12a and on either side of a radial plane P passing through the center of the ball 4. The radial portion 12c has a radial dimension smaller than that of the radial portion 12b and also has a reduced thickness due to a slight inward curvature toward the ball 4, so that the radial portion 12c rests against the insert element 10 and axially preloads 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.
[0031] The casing 8 also includes an inner axial portion 12d, which is a smaller diameter edge of the radial portion 12b and extends axially inward, for centering the prestressing element 11 inside the casing 8.
[0032] The prestressing element 11, which is annular in shape, is mounted in abutting axial contact with the radial portion 12b of the casing 8 and the insert element 9, and is radially mounted between the outer axial portion 12a and the inner axial portion 12d, remaining at a distance therefrom. The radial face of the prestressing element 11 is in axial contact with the inner face of the radial portion 12b, and the opposite radial face is in axial contact with the insert element 9. The prestressing element 11 remains at a distance from the ball 4. The prestressing element 11 exerts a permanent axial force on the insert element 9, which tends to prestress the ball 4 against the other insert element 10 and the groove of the inner ring 2.
[0033] The prestressing element 11 is advantageously made from an elastic material, for example an elastomer such as nitrile rubber or polyurethane. In the embodiment shown, the prestressing element 11 takes the form of a torus with a square cross section. As a variant, it is conceivable to provide the prestressing element 11 with a different profile for the straight sections, for example circular.
[0034] The beads 9, 10 each take the form of an open torus and are mounted inside the casing 8 in direct contact therewith. The balls 4 are arranged between the beads 9, 10 of the outer ring 3 and the bearing race 7 of the inner ring 2, which form the bearing race. This creates a rolling bearing 1 with three contact points. In the exemplary embodiment shown, the beads 9, 10 are identical in order to reduce manufacturing costs.
[0035] As shown more clearly in Figure 2, the bearing race 7 of the inner ring is provided with a first axial end e1 and a second axial end e2, which define the axial length of the bearing race 7. The first axial end e1 and the second axial end e2 are offset radially, i.e., inwardly, on opposite sides of the outer ring 3 relative to the outer axial annular surface 6. The first axial end e1 and the second axial end e2 are aligned in the axial direction.
[0036] The first axial end e1 is axially located on the same side as the prestressing element 11 with respect to a radial plane P passing through the center of the ball 4, and the second axial end e2 is axially located on the opposite side.
[0037] The inner ring 2 is frusto-conical in shape and includes a first annular thrust surface 13a extending obliquely outwardly towards the outer ring 3 from a first axial end e1 of the bearing race 7 to the outer axial annular surface 6. The thrust surface 13a is connected on one side to the outer axial annular surface 6 of the inner ring 2 and on the other side to the bearing race 7. The thrust surface 13a thus extends between the first axial end e1 of the bearing race 7 and the annular surface 6 of the inner ring 2. The thrust surface 13a may be connected to the annular surface 6 via a chamfered surface.
[0038] In the straight portion, the thrust surface 13a extends obliquely from the first axial end e1 onto the inside of the concave inner profile of the bearing race 7. In other words, the thrust surface 13a is closed towards the inside of the arc of the bearing race 7.
[0039] In the linear portion, the thrust surface 13a intersects with an oblique line d1 connecting the first axial end e1 of the bearing race 7 of the inner ring 2 with the tangent point between the ball 4 and the axially opposite insert element 10. The angle formed between the thrust surface 13a and this oblique line d1 can be, for example, between 25° and 85°. The inner ring 2 also includes a second thrust surface 13b extending obliquely from the second axial end e2 of the bearing race 7 toward the outer ring 3 as far as the outer axial annular surface 6. The thrust surface 13b is connected on one side to the outer axial annular surface 6 of the inner ring 2 and on the other side to the bearing race 7. The second thrust surface 13b thus extends between the second axial end e2 of the bearing race 7 and the annular surface 6 of the first inner ring 2. The thrust surface 13b may be connected to the annular surface 6 via a chamfered surface.
[0040] In the straight portion, the thrust surface 13b extends obliquely from the second axial end e2 onto the inside of the concave inner profile of the bearing race 7. In other words, the thrust surface 13b is closed towards the inside of the arc of the bearing race 7.
[0041] In the straight section, the thrust surface 13b intersects with an oblique line d2 connecting the second axial end e2 of the bearing race 7 of the inner ring 2 and the point of contact between the ball 4 and the axially opposite insert element 9. The angle formed between the thrust surface 13b and this oblique line d2 may be, for example, between 25° and 85°.
[0042] The thrust surfaces 13 a and 13 b may be symmetrical about a radial plane P passing through the center of the ball 4 .
[0043] These faces 13a, 13b of the inner ring form an axial restraint making it possible to prevent the axial movement of the row of balls 4.
[0044] In this exemplary embodiment, the outer ring 3 comprises two insert elements 9, 10 in the casing, which take the form of beads for forming the bearing races of the outer ring.
[0045] Alternatively, other designs of the outer ring may be provided.
[0046] For example, as shown in FIG. 3, in which like elements bear like reference numerals, the outer ring 3 includes an insert element 9 having the form of a cup that defines a bearing race for the ball 4 .
[0047] In the exemplary embodiment shown in Figure 4, in which like elements have the same reference numerals, the outer ring 3 comprises a single insert element 10 in the form of a cup, which defines a bearing race for the balls 4, and the casing 8 comprises an oblique extension 12d extending obliquely from the inner axial portion 12d and which defines a bearing race for the balls 4. In this example, the prestressing element 11 is arranged axially between the radial portion 12c of the casing and the insert element 10.
[0048] As indicated in the previous paragraph, in the exemplary embodiment shown, the first ring 2 of the bearing is the inner ring and the second ring 3 is the outer ring. Alternatively, the reverse arrangement can be provided, in which the first ring 2 is the outer ring and the second ring 3 is the inner ring. In this case, the bearing race 7 and the thrust surface or surfaces 13a, 13b are formed on a bore in the outer ring that forms the inner surface of said rings. [Explanation of symbols]
[0049] 1. Rolling bearings 2 First ring, inner ring 3 Second ring, outer ring 4 balls 5 cages 6 outer axial annular surface 7 Bearing race 8 Outer casing 9, 10 Insert elements, beads 11 Prestressing elements 12a Outer axial section 12b, 12c radial section 12d Inner axial portion, diagonal extension 13a first annular thrust surface 13b Second thrust surface d1, d2 diagonal straight line e1 First shaft end e2 Second shaft end P radius surface
Claims
1. 1. A 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 the rings (2, 3), the second ring (3) comprising a casing (8), at least one insert element (9) arranged in the casing (8) to form a bearing race of the second ring (3), and at least one prestressing element (11) mounted in the casing (8) and applying an axial force to the insert element (9), characterized in that the first ring (2) is provided, in a straight section, with a bearing race (7) having a concave inner profile and at least one first thrust surface (13a) extending obliquely outward from a first axial end (e1) of the bearing race (7) towards the second ring (3).
2. 2. A bearing (1) according to claim 1, wherein the thrust surface (13a) of the first ring (2) is frusto-conical in shape.
3. 3. A bearing (1) according to claim 1 or 2, wherein the first ring (2) includes an annular surface (6) from which the bearing race (7) is formed, and the thrust surface (13a) is connected to the annular surface (6).
4. 4. The bearing (1) according to claim 1, wherein in a straight section, the thrust surface (13a) extends obliquely from the first axial end (e1) on the inside of the concave inner profile of the bearing race (7).
5. 5. The bearing (1) according to claim 1, wherein the first ring (2) comprises a second thrust surface (13b) extending obliquely outwardly towards the second ring (3) from a second axial end (e2) of the bearing race (7) opposite the first axial end (e1).
6. 6. The bearing (1) according to claim 5, wherein the second thrust surface (13b) of the first ring (2) is symmetrical to the first thrust surface (13a) with respect to a radial plane (P) passing through the center of the ball (4).
7. 7. A bearing (1) according to any one of claims 1 to 6, wherein the second ring (3) comprises two insert elements (9, 10) arranged in the casing (8) on either side of the radial plane (P) passing through the centre of the ball (4).
8. 8. 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. 9. A 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 said housing and said shaft.