Roller bearing with asymmetric raceways, in particular for steering column
By adopting a combined design of asymmetric raceways and prestressed elements in the steering column roller bearing, the problems of free clearance and friction torque of the bearing when adjusting the preload are solved, and the axial stiffness of the bearing and the stability of the steering system are improved.
Patent Information
- Application Number
- CN202510273306.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-13
- Filing Date
- 2025-03-10
- Publication Date
- 2025-09-16
AI Technical Summary
Existing steering column roller bearings have difficulty in simultaneously preventing bearing free play and restricting axial movement when adjusting the preload, resulting in increased friction torque and affecting the stability and efficiency of the steering system.
A roller bearing is designed in which the raceway of the first ring has an asymmetric concave inner profile in cross section, the radius of the first arc-shaped part is larger than the radius of the second arc-shaped part, and different compressive forces are applied in the axial direction through prestressing elements to limit axial movement while maintaining small friction torque.
The combination of asymmetric raceway design and prestressed elements achieves smaller axial deflection and improved axial stiffness of the bearing, reduces friction torque, and improves the stability and efficiency of the steering system.
Smart Images
Figure CN120650326A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of roller bearings, in particular roller bearings used in steering columns of motor vehicles. Background Art
[0002] A steering column generally comprises a shaft, one end of which is rigidly connected to a steering wheel actuated by the driver of the vehicle, and the other end of which is rigidly connected to a mechanical member intended to perform angular positioning of the vehicle's wheels. The shaft of the steering column is rotatably mounted in a tubular housing by means of two roller bearings.
[0003] One type of roller bearing for steering columns comprises an inner ring, an outer ring, and an array of balls arranged between the raceways of the rings. At least one of the rings comprises a casing and an insert arranged in the casing to form the raceways of the rings. This results in a roller bearing with three or four contact points that can operate under axial and / or radial loads. Typically, such bearings also include an elastic prestressing element mounted in the casing and pressing axially against one of the inserts to achieve operation with limited movement.
[0004] The architecture of this roller bearing prevents free play in the bearing even when the preload of the bearing is adjusted after assembly, without completely restricting axial and radial movement between the rings.
[0005] Therefore, the present invention aims to overcome these disadvantages. Summary of the Invention
[0006] The present invention relates to a roller bearing, in particular a roller bearing for a steering column, comprising a first ring, a second ring and at least one row of balls arranged between the rings, the second ring comprising: a casing; at least one insert arranged in the casing so as to form a raceway for the second ring; and at least one prestressing element installed in the casing and exerting an axial force on the insert.
[0007] "Insert" refers to an element that is separate from the housing.
[0008] According to one general feature, the first ring is provided with a raceway for the balls having, in section, a concave inner profile that is asymmetrical with respect to a plane parallel to a radial plane passing through the centre of the balls.
[0009] Therefore, the osculation, which is the ratio between the curvature of the raceway and the diameter of the ball, has different values on two sides of a radial plane passing through the center of the ball.
[0010] Advantageously, in cross section, the concave inner profile of the raceway of the first ring comprises a first arc having a first radius and a second arc having a second radius, the first arc being axially located on the same side as the prestressing element and the second arc being axially located on the opposite side to the prestressing element, the first arc and the second arc having different centers and the first radius being greater than the second radius.
[0011] Said asymmetrical concave inner profile of the raceway of said first ring makes it possible to limit the relative axial movements of said rings.
[0012] As long as the smallest radius of the raceway is axially located on the opposite side of the prestressing element, during operation the balls of the row will tend to rise more quickly on this part of the raceway, which will cause a greater compression of the prestressing element and in turn a greater prestress applied by said element.
[0013] Therefore, the roller bearing will allow smaller axial deflections for equivalent prestressing force without compromising the friction torque. This also makes it possible to increase the axial stiffness of the bearing.
[0014] By way of example, the radius of the first arc of said raceway of the first ring is between 110% and 130%, in particular equal to 120%, of the radius of the second arc.
[0015] Advantageously, the first ring comprises an annular surface from which the raceway is formed and which the arcs engage. Alternatively, it is conceivable that there is an engagement surface between each arc and the annular surface.
[0016] Optionally, each arcuate member engages the annular surface by a chamfer.
[0017] In one embodiment, the arcs of the concave inner profile of the raceway engage each other at points belonging to a plane parallel to a radial plane passing through the center of the ball. Alternatively, cylindrical engagement surfaces between the arcs can be envisaged.
[0018] In one embodiment, the second ring comprises two inserts arranged in the casing on either side of a radial plane passing through the centre of the ball.
[0019] Advantageously, the two inserts of the second ring are identical.
[0020] In one embodiment, the first ring is an inner ring of the roller bearing, and the second ring is an outer ring of the roller bearing.
[0021] The present invention also relates to a steering column comprising a housing, a shaft coaxial with the housing, and at least one roller bearing as described above, the roller bearing being mounted radially between the housing and the shaft. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Other objects, features and advantages of the present invention will become apparent on reading the following description, given purely by way of non-limiting example, and with reference to the accompanying drawings, in which:
[0023] [ Figure 1 ] is an axial cross-sectional view of a roller bearing according to an exemplary embodiment;
[0024] [ Figure 2 ]yes Figure 1 Detailed view of
[0025] [ Figure 3 ] is a detailed cross-sectional view of a roller bearing according to another exemplary embodiment; and
[0026] [ Figure 4 ] is a detailed cross-sectional view of a roller bearing according to yet another exemplary embodiment. DETAILED DESCRIPTION
[0027] Figure 1 A roller bearing, designated by reference numeral 1, is shown and includes a first race 2, a second race 3, and balls 4 arranged in a row between the races 2 and 3. In this embodiment, the roller bearing 1 includes a cage 5 radially arranged between the races 2 and 3 to maintain uniform circumferential spacing between the balls 4. Alternatively, the roller bearing 1 may be devoid of the cage 5.
[0028] In this embodiment, the first ring 2 is the inner ring of the roller bearing 1 , and the second ring 3 is the outer ring of the roller bearing 1 .
[0029] The inner ring 2 comprises a cylindrical hole axially delimited by opposite radial front end faces and an outer axial annular surface 6 from which a circular annular groove is formed, which has a concave inner profile in cross section suitable for forming a raceway 7 for the balls 4, the groove being oriented radially outwards.
[0030] As will be described in more detail below, the raceway 7 of the inner ring 2 has, in section, a concave inner profile that is asymmetric relative to a plane P′ parallel to a radial plane P passing through the centre of the ball 4 .
[0031] The inner ring 2 is solid. A "solid ring" is a ring that obtains its shape by machining a tube, bar, or forged and / or rolled blank using stock removal (turning, grinding).
[0032] The outer ring 3 comprises two separate inserts 9 and 10 forming the raceway for the balls 4 of the ring 3, and an outer casing 8. Here, the inserts 9 and 10 are in the form of two separate wires. The outer ring 3 also comprises a prestressing element 11 that applies an axial force to one of the inserts 9 and 10. The inserts 9 and 10 and the prestressing element 11 are mounted within the casing 8.
[0033] The housing 8 can advantageously be manufactured by cutting and forming sheet metal. The annular housing 8 includes an outer axial portion 12a, which is extended radially inward at each end by radial portions 12b, 12c. Inserts 9, 10 are arranged to radially contact the bore of the axial portion 12a and are disposed in the housing 8 on either side of a radial plane P passing through the center of the ball 4. The radial portion 12c has a smaller radial dimension than the radial portion 12b and also has a reduced thickness, causing the radial portion 12c to curve slightly toward the ball 4, pressing against the insert 10 and axially prestressing the bearing 1. The cage 5 is disposed radially between the free edge of the radial portion 12c of the housing 8 and the outer surface of the inner ring 2.
[0034] The housing 8 further comprises an inner axial portion 12d which extends axially inwardly by the edge of the smaller diameter of the radial portion 12b. The axial portion 12d is provided for centering the prestressing element 11 within the housing 8.
[0035] An annular prestressing element 11 is mounted axially in contact with radial portion 12b of housing 8 and insert 9, and radially between outer axial portion 12a and inner axial portion 12d while maintaining a distance therefrom. One radial surface of prestressing element 11 is in axial contact with the inner surface of radial portion 12b, and the opposite radial surface is in axial contact with insert 9. Prestressing element 11 is maintained at a distance from ball 4. Prestressing element 11 exerts a permanent axial force on insert 9, which tends to prestress ball 4 on the other insert 10 and the groove of inner ring 2.
[0036] The prestressing element 11 is advantageously formed of an elastic material, for example an elastomer such as nitrile rubber or polyurethane. In the embodiment shown, the prestressing element 11 is in the form of a torus with a square cross-section. As a variant, the prestressing element 11 can be conceived to have another cross-sectional profile, for example a circular shape.
[0037] Inserts 9, 10 are in the form of open torus rings and are mounted in direct contact with housing 8. Balls 4 are arranged between inserts 9, 10, which form the raceway of outer ring 3, and raceway 7 of inner ring 2. This creates a roller bearing 1 with three contact points. In the exemplary embodiment shown, inserts 9, 10 are identical, thereby reducing manufacturing costs.
[0038] like Figure 2 、 Figure 3 and Figure 4 As shown more clearly in FIG, the raceway 7 of the inner ring 2 is provided with a first axial end e1 and a second axial end e2, which define the axial length of the raceway 7. The first axial end e1 and the second axial end e2 are joined to the annular surface 6 of the inner ring 2. The first axial end e1 and the second axial end e2 are aligned with respect to the axial direction.
[0039] 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.
[0040] As in Figure 2 As shown more clearly in FIG, in section, the raceway 7 of the inner ring 2 has a concave inner profile that is asymmetrical with respect to a plane P′ parallel to a radial plane P passing through the centre of the ball 4 .
[0041] The concave inner profile of the raceway 7 comprises a first arc 13a with a radius r1 and a second arc 13b with a radius r2, the first arc 13a being axially located on the same side as the prestressing element 11 and the second arc 13b being axially located on the opposite side to the prestressing element 11. Figure 1 and Figure 2 In the embodiment shown, radius r1 is greater than radius r2. The first arc 13a and the second arc 13b have different centers C1 and C2. Center C1 lies in a radial plane P, and center C2 lies in a plane P' parallel to radial plane P. Center C1 is radially offset relative to center C2 on the same side as the outer ring 3, and axially offset relative to center C2 on the side opposite to the prestressing element 11. Plane P' is axially offset relative to plane P on the same side as the first end e1. The axial offset of plane P from plane P' is shown by the double arrow denoted by d. The arc 13a extends from the first axial end e1 of the raceway 7 to a radial plane P" parallel to plane P. In the embodiment shown in the figure, plane P" is axially offset relative to plane P on the opposite side of the prestressing element 11.
[0042] The arc 13b extends from the axial end e2 of the raceway 7 to a radial plane P". The arcs 13a, 13b therefore join one another at a point 14 coinciding with the plane P".
[0043] For example, for a roller bearing with a ball diameter equal to 3.969 mm, the radius r1 of the arc 13a can be equal to 2.4 mm and the radius r2 of the arc 13b can be equal to 2 mm. Preferably, the radius r1 is between 110% and 130% of the radius r2, in particular equal to 120%.
[0044] In this exemplary embodiment, the outer ring 3 comprises two inserts 9 , 10 in the form of wires in the housing, so that the raceway of the outer ring is formed.
[0045] As a further alternative, other designs of the outer ring are conceivable.
[0046] For example, Figure 3 As shown, in Figure 3 In this embodiment, in which identical elements bear identical reference numerals, the outer ring 3 comprises an insert 9 in the form of a cup defining a raceway for the balls 4 .
[0047] exist Figure 4 In the embodiment shown, Figure 4, in which identical elements bear identical reference numerals, the outer ring 3 comprises a single insert 10 in the form of a cup defining a raceway for the balls 4, and the housing 8 comprises an inclined extension 12 d extending obliquely the inner axial portion 12 c and defining a raceway for the balls 4. In this example, a prestressing element 11 is arranged axially between the radial portion 12 c of the housing and the insert 10.
[0048] As mentioned above, 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 opposite configuration is conceivable: the first ring 2 is the outer ring, and the second ring 3 is the inner ring. In this case, a raceway 7 with an asymmetrical concave inner profile is formed in the bore of the outer ring, which forms the inner surface of the rings.
Claims
1. A roller 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), wherein the second ring (3) comprises: housing (8); at least one insert (9) arranged in the housing (8) so as to form a raceway for the second ring (3); and at least one prestressing element (11) mounted in the housing (8) and exerting an axial force on the insert (9), characterized in that the first ring (2) is provided with a raceway (7) for the balls (4), the raceway (7) having, in cross section, a concave inner profile that is asymmetrical with respect to a plane (P') parallel to a radial plane (P) passing through the center of the balls (4).
2. The bearing (1) according to claim 1, characterized in that In cross section, the concave inner profile of the raceway (7) of the first ring comprises a first arc (13a) having a radius (r1) and being axially located on the same side as the prestressing element (11), and a second arc (13b) having a radius (r2) and being axially located on the opposite side to the prestressing element (11), the first arc and the second arc having different centers (C1, C2) and the radius (r1) being strictly greater than the radius (r2).
3. The bearing (1) according to claim 2, characterized in that The radius (r1) is between 110% and 130% of the radius (r2).
4. The bearing (1) according to any one of claims 1 to 3, characterized in that The first ring (2) comprises an annular surface (6), the raceway (7) is formed starting from the annular surface (6), the arcs (13a, 13b) engaging the annular surface (6).
5. The bearing (1) according to claim 4, characterized in that Each arc (13a, 13b) engages the annular surface (6) by chamfering.
6. The bearing (1) according to any one of claims 1 to 5, characterized in that The arcs (13a, 13b) of the concave inner profile of the raceway (7) of the first ring (2) join each other at points (14) belonging to a plane (P') parallel to a radial plane (P) passing through the center of the ball (4).
7. The bearing (1) according to any one of claims 1 to 6, characterized in that The second ring (3) comprises two inserts (9, 10) arranged in the housing (8) on either side of a radial plane (P) passing through the center of the ball (4).
8. The bearing (1) according to claim 7, characterized in that The two inserts (9, 10) of the second ring (3) are identical.
9. The bearing (1) according to any one of claims 1 to 8, characterized in that The first ring (2) is the inner ring of the roller bearing (1), and the second ring (3) is the outer ring of the roller bearing (1).
10. A steering column comprising a housing, a shaft coaxial with the housing, and at least one roller bearing (1) according to any one of claims 1 to 9 mounted radially between the housing and the shaft.