Recirculating ball segment for an adjusting unit of a steering column

Abstract

The invention relates to a recirculating ball segment (1) for an adjusting unit of a steering column of a vehicle, comprising a cage (15) which at least partially forms support channels (3) and return channels (4) of two recirculating ball guides, a plurality of balls (5) which are arranged in the support channels (3) and return channels (4), and a spring element (6) by means of which the balls (5) located in support channels (3) are spring-loaded, with a load direction (8) which is oriented perpendicular to a plane formed by the support channels, and a movement direction (9) which extends in the direction of the support channels (3), wherein the spring element (6) is rounded in a central region (7) which is adjacent to the return channels in the load direction (8), transverse to the movement direction (9) of the recirculating ball segment (1).

Description

[0001] Title of the invention

[0002] Ball bearing segment for an adjustment unit of a steering column

[0003] Description

[0004] Field of the invention

[0005] The present invention relates to a ball bearing segment for an adjusting unit of a steering column of a vehicle, in particular for a steer-by-wire steering system with such an adjusting unit.

[0006] Background of the invention

[0007] Today's steering columns feature a height- and reach-adjustable steering wheel. With such steering column adjustment systems, the steering column housing sections must be able to move relative to each other. This is achieved by a telescopic arrangement of the housing sections. This allows the steering wheel to be adjusted to a position that suits the driver. Recently, there has been a requirement for the steering wheel to be retracted into a stowed position in the dashboard.

[0008] To achieve sufficient adjustment range, DE 10 2015 216 326 A1 discloses arranging several jacket tubes so that they can be telescopically moved inside one another. To adjust the stowage position, the jacket tubes can be pushed together until they are almost completely recessed.

[0009] To adjust the steering column quickly and safely, it is essential that the steering column tubes can move smoothly relative to each other, i.e., slide smoothly with minimal friction. For this purpose, plain bearings are often used. In contrast, the steering wheel requires a very rigid bearing to prevent it from swinging while driving.

[0010] DE 10 2022 132 487 A1 discloses a bearing arrangement in which recirculating ball segments are used to achieve radially rigid bearing support with smooth axial adjustment. To enable play-free and preloaded installation, the recirculating ball segments are equipped with a spring element. However, the stroke achievable with the spring element for setting a defined preload is very small.

[0011] Summary of the invention

[0012] The object of the invention is to provide a ball bearing segment for a bearing arrangement of a steering column housing of a motor vehicle, which has a sufficient stroke for adjusting a preload and thus enables a safe and quick adjustment of the steering column while at the same time ensuring high radial rigidity of the steering wheel.

[0013] According to the invention, this object is achieved by a recirculating ball segment for an adjusting unit of a steering column of a vehicle, comprising a cage which at least partially forms support channels and return channels of two recirculating ball guides, a plurality of balls which are arranged in the support channels and return channels, and a spring element by which the balls located in the support channels are spring-loaded, with a loading direction which is oriented perpendicular to a plane formed by the support channels and a direction of movement which runs in the direction of the support channels, wherein the spring element is designed to be crowned transversely to the direction of movement of the recirculating ball segment in a central region which is arranged adjacent to the return channels in the loading direction.

[0014] Such a design allows for adjustment of the steering column with low friction and high rigidity. Advantageously, several recirculating ball segments are arranged distributed around the circumference. The spring element is preferably designed as a spring plate.

[0015] According to one embodiment of the invention, the spring element has a first and a second outer region, which adjoin the central region and form raceways for the balls. The raceways preferably have a flat shape. Such a shape has the advantage that during assembly the flat regions rest against the balls and the central region is bent inwards. The spherical outer shape of the central region before assembly prevents the spring element from bending inwards and thereby exerting a radial load on the cage of the recirculating ball segment. The deformation is elastic, so that the spring plate returns to its spherical outer shape as soon as the load is no longer present.

[0016] Furthermore, it is advantageous if the spherical central region of the spring element is separated from the outer regions by a step. This advantageously creates installation space for the return channels of the ball guide. This design also results in two different levels of rigidity. During assembly, the spherical central region is deformed first. Advantageously, the spherical central region is spaced from the cage and the balls of the return channels in the load direction in such a way that the deformation caused by installation can be absorbed in such a way that the spring element does not engage with the cage and / or the balls in the central region absorbing the main deformation. This prevents load from being introduced into the cage and also enables unhindered return of the balls in the return channels.

[0017] During operation, additional loads can occur, leading to further deformation of the spring plate. Once the displacement determined by the first stiffness of the crowned central region has been exhausted and the crowned region has assumed a substantially flat shape, the load is no longer introduced only centrally into the spring plate, but can be supported laterally via the steps on the balls with a lever arm that is very short compared to the central load. This achieves a second stiffness that is higher than the first stiffness.

[0018] For the purposes of the invention, a crowned shape is therefore one in which the spring plate rests in a central region against a flat surrounding component, in the case of a steering system in particular in the generally polygonal, e.g. hexagonal or octagonal, casing tubes. This can preferably be a fully crowned shape with a constant radius, but other shapes are also possible, such as a centrally protruding part. The decisive factor according to the invention is that the crowned shape enables elastic deflection mainly via contact and deformation in the central region, while contact in a region further out only occurs with increased deformation that goes beyond the deformation caused by the assembly itself.

[0019] If the spring plate has a constant radius of curvature in its central section, it can be designed particularly easily in terms of spring travel and stiffness. The central section describes at least the area between the return channels; however, it can also extend beyond them.

[0020] In another design, the radius of curvature is not constant across the central region. This allows for the definition of regions that deform disproportionately or disproportionately compared to a spring plate with a constant radius of curvature, in order to optimally adapt the spring travel to the available free spaces in the cage. In particular, the central region can be convex. The advantage of crowning is that the implied curvature provides a smooth curve, which improves the spring deflection behavior in the event of oblique and off-center forces acting on the spring plate.

[0021] In the case of partial crowning, crowning occurs only in the central region. On the outer side, there may be an area where the spring plate is flat. Alternatively or additionally, the central region is separated from the outer regions by chamfers or steps. Pockets may be provided in the steps to reduce stiffness if necessary to facilitate spring deflection.

[0022] The cage can be made of plastic. This allows for additional functions to be implemented on the cage. For example, the cage can be provided with compression ribs between which the spring plate is clamped. This effectively holds the recirculating ball segment together before installation.

[0023] In a further embodiment, pins are formed on the ball bearing segment, advantageously on the cage, with which the ball bearing segment can be positioned in the casing tubes of the adjustment unit.

[0024] Further aspects of the invention relate to a steer-by-wire steering system using an adjusting unit with at least one recirculating ball segment according to the invention.

[0025] Short description of the drawing

[0026] An exemplary embodiment of the invention is illustrated below with reference to three figures. Fig. 1 shows a 3D overall view of a ball bearing segment according to the invention,

[0027] Fig. 2 is a 3D exploded view of a ball bearing segment according to the invention, and

[0028] Fig. 3 shows a cross section transverse to the direction of movement through a ball bearing segment according to the invention.

[0029] Detailed description of the drawing

[0030] Figures 1 to 3 show different views of a ball bearing segment 1 according to the invention of an adjustment unit not shown in detail.

[0031] Figure 1 shows a 3D view of an assembled recirculating ball segment 1. Visible components of the recirculating ball segment 1 are a spring element 6 designed as a spring plate 10 and a cage 15. The cage 15 is made of plastic. The spring plate 10 is positively connected to the cage 15 via crush ribs 16. The cage 15 also has two pins 17 for connection to a casing tube (not shown) of an adjustment unit. The spring plate 10 has a central region 7 which is arranged between two steps 14. The steps 14 separate the central region 7 from the first and second outer regions 11, 12. A direction of movement 9 of the recirculating ball segment 1 runs in the direction of the support channels 3 (not visible in Figure 1). The central region 7 of the spring plate 10 is crowned transversely to the direction of movement 9.

[0032] In Figure 2, the spring plate 10 is shown separated from the cage 15 for better visibility. For the elements of the spring plate 10 and the cage 15 already shown in Figure 1, reference is made to the description of Figure 1. Furthermore, the cage 15 has two recirculating ball bearing guides 2. These each consist of a support channel 3 and a return channel 4, which are connected at their ends via deflections. Balls 5 are also arranged in the recirculating ball bearing guides 2.

[0033] Figure 3 shows a sectional view through the recirculating ball segment 1 in a plane perpendicular to the direction of movement 9. The two support channels 3 of the two recirculating ball guides 2 are located on the outside, while the return channels 4 are located on the inside. The balls 5, which are located in the support channels 3, are supported on raceways 13 of the first and second outer regions 11, 12. The first and second outer regions 11, 12 are separated by steps 14 from the central region 7, which is crowned in the loading direction 8 and transverse to the direction of movement 9.The central region 7 is spaced apart in the load direction 8 from the balls 5, which are located in the return channels 4, so that a deformation due to installation in the load direction 8 is mainly absorbed by the central region 7, without the central region 7 coming into contact with the cage 15 or the balls 5, so that no load is exerted on the cage 15 or on the balls 5 located in the return channel 4, so that the balls 5 can move in the return channels 4 with little friction.

[0034] In the installation case not shown, the recirculating ball segment 1 is loaded via the casing tubes (not shown) of the adjustment unit and the spherical central region 7 is at least partially deformed towards a flat shape. The load is introduced by a flat surface of the casing tube (not shown). As soon as the spherical central region 7 of the spring plate 10 has absorbed so much movement that the surface of the casing tube lies flat on the central part 7, a further increase in load, for example due to an operating load, causes the additional force to be transmitted directly via the steps 14 and the running surfaces 13 into the balls 5 in the support channel 3 and their counter-running surfaces (not shown). As a result, once the deformation of the spherical central region 7 has been overcome, the rigidity of the assembly increases. The deformation is elastic, so that the spring plate 10 returns to its spherical outer shape as soon as the load is no longer present.

[0035] List of reference symbols

[0036] ball bearing segment

[0037] recirculating ball bearing guide

[0038] Support channel

[0039] Return channel

[0040] balls

[0041] spring element

[0042] Middle range

[0043] Load direction

[0044] Direction of movement

[0045] spring plate

[0046] First outer area

[0047] Second outer area

[0048] career

[0049] Level

[0050] cage

[0051] crush ribs

[0052] cones

Claims

Patent claims 1 . Ball bearing segment (1 ) for an adjusting unit of a steering column of a vehicle, comprising - a cage (15) which at least partially forms support channels (3) and return channels (4) of two recirculating ball bearing guides (2), - a plurality of balls (5) arranged in the support channels (3) and return channels (4), and - a spring element (6) by which the balls (5) located in support channels (3) are spring-loaded, - with a loading direction (8) which is oriented perpendicular to a plane formed by the support channels (3) and - a direction of movement (9) which runs in the direction of the support channels (3), characterized in that the spring element (6) is spherical in a central region (7) which is arranged adjacent to the return channels (4) in the loading direction (8), transversely to the direction of movement (9) of the ball circulation segment (1).

2. Ball bearing segment (1) according to claim 1, characterized in that the spring element (6) is designed as a spring plate (10).

3. Ball circulation segment (1) according to one of the preceding claims, characterized in that the spring element (6) has a first (11) and a second outer region (12) which adjoin the central region (7) and form raceways (13) of the balls (5).

4. Ball bearing segment (1) according to claim 3, characterized in that that the middle (7) and the outer regions (11, 12) of the spring element (6) are each separated by a step (14).

5. Ball bearing segment (1) according to claim 4, characterized in that in the loading direction (8) a first stiffness results from the deformation of the central region (7) of the spring element (6) and a second stiffness, which is higher than the first stiffness, results from force introduction adjacent to the steps (14).

6. Ball recirculating segment (1) according to one of the preceding claims, characterized in that the central region (7) of the spring element (6) is spaced from the balls (5) and a cage (15) in such a way that it can absorb an installation preload in the loading direction (8) by deformation in such a way that the spring element (6) in the central region (7) does not engage with the cage (15) and / or the balls (5).

7. Ball bearing segment (1) according to one of claims 2 to 6, characterized in that the spring plate (10) is held in position in the unloaded state by crush ribs (16) on the cage (15).

8. Ball-bearing segment (1) according to one of claims 2 to 7, characterized in that the ball-bearing segment (1) can be positioned in an adjusting unit by means of pins (17) formed from the cage (15).

9. Adjustment unit of a steering column of a vehicle comprising a ball-bearing segment (1) according to one of the preceding claims.

10. Steer-by-wire steering system comprising an adjustment unit according to claim 9.

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