Steering column bearing with a mounting unit

Abstract

The invention relates to a steering column bearing (1), designed as an angular contact ball bearing, for mounting a steering shaft (2) of a motor vehicle, consisting of an inner bearing ring (4) and an outer bearing ring (5), between which rolling elements (7), which are distributed over the circumference, are guided on associated raceways (8, 9), wherein: the steering column bearing (1) is secured against axial shifting by means of a mounting unit (10) positioned on the steering shaft (2), which mounting unit (10) has a spring function, a clamping function and a retaining function; the mounting unit (10), which achieves a progressive or regressive spring characteristic curve, includes tooth-like segments (13) orientated axially and engaging between the inner bearing ring (4) and the steering shaft (2), and claws (14) which are circumferentially distributed and force-lockingly and / or friction-lockingly supported on the steering shaft (2).

Description

[0001] Steering column bearing with one mounting unit

[0002] The invention relates to a steering column bearing designed as an angular contact ball bearing for supporting a steering shaft of a motor vehicle, with the features of the preamble of claim 1.

[0003] The steering column connects a manually rotatable steering wheel to the steerable wheels of a vehicle's steering axle. The steering column must fulfill both safety and comfort requirements. Prior art reveals steering columns for motor vehicles in which the steering shaft (also called the steering column) is supported within the steering shaft housing by means of a bearing pair consisting of two mutually preloaded angular contact ball bearings in an O-bearing arrangement, allowing for rotation with minimal friction. The upper steering column bearing primarily determines the stiffness of the steering wheel. The preload of the steering column bearing can be achieved by a tolerance ring made of plastic, supported on the steering shaft, and incorporating an integrated spring element.

[0004] DE 38 08 556 A1 discloses a steering column bearing in which the inner bearing of the upper angular contact ball bearing is supported by a tolerance ring made of plastic, to which a spring element is held by a locking washer. The steering column bearing, together with the tolerance ring and the retaining element, forms a single unit. To achieve improved stiffness of the steering column and consequently the steering wheel, DE 10 2019 113232 A1 describes a solid steel inner ring pressed directly onto the steering shaft instead of the plastic tolerance ring, but this negatively affects the assembly sequence of the steering column bearing.

[0005] Further steering column bearings are known from US 6,227,715 B1 and EP 1,988,002 A1. The object of the invention is to provide a functionally improved, backlash-free bearing for steering columns compared to the prior art, with a design that simplifies assembly and enables a radially stiff, cost-effective steering column bearing, combined with high stiffness at the steering wheel.

[0006] This problem is solved by means of a displacement unit constructed according to the features of claim 1 and a method according to claim 10. Further preferred embodiments of the invention can be found in the dependent claims, the figures and the accompanying description.

[0007] According to the invention, a pre-assembled, rotationally symmetrical, one-piece or multi-piece assembly unit with multiple functions is provided as a preloading element for the steering column bearing. This assembly unit, which can also be referred to as a fastening or preloading assembly and is completely pre-assembled before installation, ensures the integration of a clamping function, a spring function, and an axial holding function for the angular contact ball bearing of the steering column bearing within a single assembly, while maintaining the previously known assembly sequence. To this end, the assembly unit, which provides a secure hold and whose spring function allows for a progressive or degressive spring characteristic, includes axially aligned, tooth-like segments that engage under the inner bearing ring of the angular contact ball bearing, as well as circumferentially distributed claws that are supported on the steering shaft by force-fit and / or friction-fit.

[0008] During installation, under axial load, the tooth-like, axially aligned segments slide into a gap between the steering shaft and the inner bearing ring of the steering column bearing. This creates a friction function that centers the steering column bearing relative to the steering shaft without play, as the spring element segments are designed with an interference fit relative to the steering shaft and / or engage in the gap with an interference fit. This installation position is secured by the claws pressed onto the steering shaft, which are part of the mounting unit. The advantage of the proposed solution lies in the fact that the mounting unit according to the invention is characterized by improved axial preload and simultaneously by high radial stiffness. This effectively prevents evasive movement of the steering shaft and thus the steering wheel in the event of an accident.In the event of a collision, such as a rear-end collision, the airbag's position remains virtually unchanged, thus ensuring a high level of crash safety. At the same time, the high preload of the steering shaft bearing prevents the steering wheel from vibrating excessively, which could negatively impact the vehicle's handling, especially at low steering column vibration frequencies.

[0009] Advantageously, the invention offers the possibility of creating a mounting unit with a progressive or degressive spring characteristic through a simple modification. Due to its simple design, the mounting unit according to the invention can be manufactured cost-effectively. Furthermore, the assembly process can be significantly simplified by simply sliding the mounting unit axially onto the steering shaft. Advantageously, the assembly sequence remains unchanged for the vehicle manufacturer compared to previous solutions. Consequently, the installation of this fully pre-assembled mounting unit, also known as a preload assembly, enables cost-optimized steering column mounting.

[0010] According to a preferred design embodiment, an assembly unit is provided consisting of two components: a spring element combined with a claw ring, which together form the pre-assemblable assembly unit. The spring element comprises axially aligned, tooth-like segments on the bearing side that interact with the angular contact ball bearing and form a contour similar to a disc spring against which the claw ring is supported. This design of the spring element allows for a progressive spring characteristic. To create a captive assembly, axial connecting tabs are preferably provided on the spring element, which engage positively and / or non-positively in corresponding recesses of the claw ring.

[0011] Alternatively, according to the invention, a pre-assembled assembly unit encompassing all components can be used, in which both the spring element and the claw ring are enclosed on the outside by a closed or slotted bushing or sleeve to form a captive assembly. With this design, which includes a bushing (also called a Torg bushing) enclosing axially aligned segments, and preferably a standard disc spring as the spring element, an assembly unit with a degressive spring characteristic can be realized.

[0012] According to the invention, it is advantageous to integrate different spring elements into the assembly unit. In addition to components designed similarly to a disc spring, standard disc springs, wave springs, or spring elements made of elastomer can be used, for example. In the installed state, the claw ring is preferably directly subjected to a force-fit, regardless of the selected spring element.

[0013] A preferred embodiment of the spring element or slotted bushing provides that its axially aligned end-face segments, forming a toothed, enclosing circle, are flattened on the outside and taper continuously towards the free end. To achieve sufficient preload of the inner bearing ring by the assembly unit, the segments, in the uninstalled state of the spring element, have an inner diameter that exceeds the steering shaft diameter. In the installed state, the segments exert a radial compressive force on the cylindrical section of the inner bearing ring, whereby the spring element or bushing is frictionally secured in the axial direction. On the opposite side, the spring element forms a radially inclined contact surface, similar to a disc spring, which interacts with the claw ring.In a mounting unit that includes a bushing, the spring element, the disc spring, and the claw ring are integrated into a radially stepped section of the bushing, with the spring element applying frictional force to the claw ring. According to a preferred further embodiment, the claw ring of the mounting unit, on the side facing away from the steering column bearing, circumferentially encloses several claws, preferably bent in a semicircular profile, which, in the installed state, fix the mounting unit in position on the steering shaft. For the frictional and / or frictional fixing of the claw ring, the inner diameter of the claws is designed to be smaller than the diameter of the steering shaft, so that after installation of the mounting unit, it is permanently fixed in the axial direction via the associated claws.

[0014] As a preferred measure to achieve a secure, non-removable connection of the components of the assembly unit, the spring element has at least three axially aligned connecting tabs, also called retaining lugs, arranged circumferentially on its inner circumference. These tabs engage positively and / or frictionally in local recesses of the claw ring or, for example, are formed by rusting into an undercut. The spring element can also be connected to the claw ring axially and / or radially in another way by means of friction and / or positive locking. This can be achieved, for example, by locally external tabs or retaining fingers on the spring element or the claw ring, which are formed by rusting into the adjacent, associated component.

[0015] According to a further embodiment, the spring element of the assembly unit, the disc spring component, incorporates several cutouts or local recesses on its outer surface to achieve or support a degressive spring characteristic. This measure results in a desired reduction in the stiffness of the spring element. Furthermore, it is advantageous to provide a spring element with different retaining finger designs or connecting tabs by which the spring element is coupled to a component of the surrounding structure. To achieve cost-effective manufacturing, all components of the assembly unit are to be produced from a metallic material using a chipless process, for example, by deep drawing or bulk forming. Additionally, to improve steering comfort, it is particularly advantageous to hone the raceways for the rolling elements of both bearing rings of the steering column bearing.

[0016] A preferred embodiment provides that a standard angular contact ball bearing is used for the steering column bearing, comprising an outer bearing ring, a set of balls as rolling elements, a rolling element cage, and an inner bearing ring, with all components being combined into a single unit. Alternatively, a full complement angular contact ball bearing without a rolling element cage can be used if required.

[0017] According to an alternative embodiment, the preload element forming an assembly unit is designed and manufactured in one piece, incorporating both the function of the claw ring and that of the spring element.

[0018] The installation of the assembly unit is carried out using a procedure that includes the following steps. First, the previously individually manufactured components of the assembly unit—the spring element and the claw ring—are joined using a positive-locking and / or non-locking connection. Then, both components of the assembly unit are coupled using a positive-locking and / or non-locking connection, for example, by means of a clip or snap connection. Next, the assembly unit is pressed onto the steering shaft and moved until it is in contact with the steering column bearing. Finally, a defined axial load is applied to the assembly unit positioned on the steering shaft. This causes the axial segments of the spring element to slide between the steering shaft and the inner bearing ring, eliminating play. Simultaneously, the claws of the claw ring secure the assembly unit in position.In comparable process steps, an assembly unit can be installed in which the components spring element and claw ring are enclosed on the outside by a bushing.

[0019] The invention is described in more detail below with reference to preferred embodiments. The following illustrates:

[0020] Fig. 1 shows a half-section of a steering column bearing in the installed state with the associated mounting unit according to the invention in a first embodiment;

[0021] Fig. 2 shows a first 3D view of the assembly unit consisting of a spring element and a claw ring according to Fig. 1;

[0022] Fig. 3 shows a second 3D view of the assembly unit according to Fig. 1;

[0023] Fig. 4 shows a first embodiment of the spring element of the assembly unit as a single component in a first 3D view.

[0024] Fig. 5 shows the spring element according to Fig. 4 as a single component in a second 3D view;

[0025] Fig. 6 shows the claw ring of the mounting unit as a single component in a 3D view;

[0026] Fig. 7 shows a second embodiment of an assembly unit according to the invention in half-section; Fig. 8 graphically illustrates a comparison of spring elements with a degressive and a progressive characteristic curve;

[0027] Fig. 9 shows a second embodiment of a spring element of the assembly unit as a single component in a first 3D view;

[0028] Fig. 10 shows the spring element according to Fig. 9 as a single component in a second 3D view;

[0029] Fig. 11 shows the assembly unit according to Fig. 7 in a 3D view with integrated spring element according to Fig. 9;

[0030] Fig. 12 shows a third embodiment of an assembly unit according to the invention with an integrated elastomer as a spring element in half-section;

[0031] Fig. 13 shows the assembly unit according to Fig. 12 in the installed state;

[0032] Fig. 14 shows a fourth embodiment of an assembly unit according to the invention with an integrated wave spring as a spring element in half-section;

[0033] Fig. 15 shows the assembly unit according to Fig. 14 in the installed state;

[0034] Fig. 16 graphically illustrates preferred preload areas of the assembly unit according to Fig. 14.

[0035] Fig. 1 shows a half-section of an angular contact ball bearing as a steering column bearing 1 in the

[0036] Installation condition in which a steering shaft 2 is rotatably mounted on a steering column within a steering shaft housing 3 of a vehicle, also referred to as a steering tube. The steering shaft 2 is supported by a bearing pair consisting of two axially spaced angular contact ball bearings preloaded against each other in an O-bearing arrangement. Figure 1 shows the upper steering column bearing 1, positioned near a steering wheel (not shown), which primarily determines the stiffness of the steering wheel. The steering column bearing 1, designed as a sheet metal bearing, comprises an inner bearing ring 4, an outer bearing ring 5, and a plurality of rolling elements 7, designed as balls, inserted in a rolling bearing cage 6. To improve steering comfort, the raceways 8, 9 for the rolling elements 6 are honed on both the inner bearing ring 4 and the outer bearing ring 5.

[0037] To achieve optimal radial stiffness, backlash-free bearing, and / or to compensate for manufacturing tolerances, a mounting unit 10, also referred to as a preload element, is assigned to the steering column bearing 1 on the side corresponding to the steering wheel. The mounting unit 10 consists of a combination of two components: a spring element 11 and a claw ring 12, which form a pre-assembled assembly. The spring element 11 comprises axially aligned, tooth-like segments 13 on the bearing side, which interact with the steering column bearing 1 and form a disc spring-like contact surface inclined towards the claw ring 12, against which the claw ring 12 is supported. The mounting unit 10, which is completely pre-assembled before installation, ensures the integration of a clamping function, a spring function, and an axial holding function for the steering column bearing 1 within a single assembly.

[0038] During assembly, the axially aligned, tooth-like segments 13 of the spring element 11 slide into a gap that tapers towards the steering column bearing 1 and is radially bounded by the steering shaft 2 and the inner bearing ring 4. This ensures that the steering column bearing 1 is centered without play relative to the steering shaft 2. To support the spreading force of the segments 13, before the installation of the mounting unit 10, the inner diameter Ds of the segment 13 of the spring element 11 exceeds the outer diameter DL of the steering shaft 2. The claw ring 12 forms several semicircular claws 14 distributed around its circumference on the side facing away from the steering column bearing 1. These claws secure the mounting unit 10 to the steering shaft 2 in its installed position. For the force-fit and / or friction-fit fixing of the claw ring 12, the inner diameter of the claws 14 is designed to be smaller than the diameter of the steering shaft 2. In the installed state, the mounting unit 10 provides several functions.A clamping function is achieved between the steering shaft 2 and the inner bearing 4. A spring function is established between the inclined, disc spring-like area of ​​the spring element 11 and the claw ring 12. Furthermore, the axial support of the claw ring 12 on the steering shaft 2 results in a holding function.

[0039] Figures 2 and 3 show the assembly unit 10 in two different 3D views. The spring element 11 and the claw ring 12 are joined together by positive and / or non-positive locking to create a captive assembly unit 10. For this purpose, the spring element 11 preferably has three circumferentially distributed axial connecting tabs 15, also referred to as retaining lugs, which engage positively and / or non-positively in corresponding recesses 16 of the claw ring 12.

[0040] Figures 4 and 5 illustrate the design of the axially aligned segments 13 of the spring element 11, which form a toothed, enclosing circle and are uniformly flattened on the outside and continuously tapered towards the free end. Figure 6 shows the claw ring 12 as a separate component, which has several rollers 14 evenly distributed around its circumference.

[0041] Fig. 7 shows a second embodiment, an alternative concept, the assembly unit 20 in half-section, with which a degressive spring characteristic can be achieved. This consists of a claw ring 22 and a standard disc spring as the spring element 21, these components being jointly enclosed on the outside by a bushing 24. The claw ring 22 and the spring element 21 are integrated in a radially stepped section 27 of the bushing 24, the claw ring 22 being supported and fixed in position against an end-face flange 25. On the side facing away from the flange 25, the bushing 24 forms an axially projecting, end-slotted projection 26 forming segments 23.

[0042] Figure 8 graphically compares spring characteristics with a degressive characteristic curve D and a progressive characteristic curve P. The spring force F is plotted on the ordinate and the spring deflection S on the abscissa. The intersection of both spring characteristics D and P lies on a straight linear curve L. The spring characteristics shown can be achieved using different spring elements that can be used in the assembly units.

[0043] Figures 9 and 10 show the spring element 19 intended for the assembly unit 10, which includes cutouts 17, also called recesses, that are positioned differently on the outside and / or have different designs. This design represents a further alternative concept for realizing a degressive spring characteristic. Furthermore, connecting tabs, referred to as retaining fingers 18, are also associated with the spring element 19 in Figures 9 and 10, via which the spring element 19 can be coupled to an adjacent component.

[0044] Fig. 11 shows in a 3D view the assembly unit 20 with the claw ring 22, the spring element 21 and the surrounding bushing 24, with whose design and component scope a degressive spring characteristic can be ensured.

[0045] Further concepts for creating a degressive spring characteristic are shown in Figures 12 to 15. The assembly unit 30 is depicted in Figures 12 and 13, the construction of which largely corresponds to that of the assembly unit 20. The difference is that the assembly unit 30 includes a spring element 31 made of an elastomer. The assembly unit 30 in its as-delivered state, before installation, is shown in Figure 12, in which the spring element 31 forms a circular cross-section. Figure 13 shows the assembly unit 30 positioned on the steering shaft 2, and thus the spring element 31 in its installed state. The elastomer spring element 31 is completely enclosed by the bushing 24 or sleeve and the steering shaft 2, whereby, due to an axial force applied to the assembly unit 30, the spring element 31 deforms elastically, forming a rectangular cross-sectional profile.

[0046] Figures 14 and 15 show the assembly unit 40 with a spring element 41 designed as a wave spring, which can initially be pre-tensioned by the manufacturer before the customer, the vehicle manufacturer, sets the desired pre-tension. This advantageously allows for optimization of the installation space that the customer would otherwise have to provide for mounting on the steering shaft 2, especially with long and / or soft wave springs. This concept enables the use of very soft characteristic springs with tolerance ranges exhibiting low spring force fluctuations.

[0047] Fig. 16 shows in a diagram an example of a preload range VH set by the manufacturer of the spring element 41 designed as a wave spring and a preload VK adjustable by the customer, including a possible tolerance.

[0048] List of reference signs

[0049] Steering column bearing, steering shaft, steering shaft housing, bearing ring (inner), bearing (outer), rolling bearing cage, rolling element, raceway (inner), raceway (outer), mounting unit, spring element, claw ring, segment, claw, connecting tab, recess, cutout, retaining finger, spring element, mounting unit, spring element, claw ring, segment, bushing, flange, attachment, section, mounting unit, spring element, mounting unit, 41 spring element

[0050] D characteristic curve (degressive)

[0051] DL outer diameter (steering shaft)

[0052] Ds inner diameter (segment)

[0053] F Spring force

[0054] L characteristic curve (linear)

[0055] P characteristic curve (progressive)

[0056] S suspension travel

[0057] VH Preload (Manufacturer)

[0058] VK Preload (Customer)

Claims

Patent claims 1. Steering column bearing (1), designed as an angular contact ball bearing, for supporting a steering shaft (2) of a motor vehicle, consisting of an inner bearing ring (4) and an outer bearing (5), between which circumferentially distributed rolling elements (7) are guided on associated raceways (8, 9), wherein the steering column bearing (1) is secured against axial displacement by means of a preload element positioned on the steering shaft (2), characterized in that a pre-assemblable mounting unit (10, 20, 30, 40), constructed in one or more parts and performing a spring function, a clamping function and a holding function, is used as a preload element, wherein the mounting unit (10, 20, 30, 40), which can trigger a progressive or a degressive spring characteristic, comprises axially aligned tooth-like segments (13, 23) engaging between the inner bearing (4) and the steering shaft (2), as well as circumferentially distributedincluding claws (14) supported on the steering shaft (2) by force-fit and / or friction-fit.

2. Steering column bearing (1 ) according to claim 1 , characterized in that the pre-assemblable assembly unit (10) consists of a spring element (11 ) and a claw ring (12) enclosing claws (14), wherein the assembly unit (10) comprises means for forming a captive assembly unit.

3. Steering column bearing (1 ) according to claim 1 , characterized in that the pre-assemblable assembly unit (20, 30, 40) includes a spring element (19, 21 , 31 , 41 ) and a claw ring (22) which are enclosed on the outside by a closed or slotted bushing (25) to form a captive assembly unit.

4. Steering column bearing (1) according to one of the preceding claims, characterized in that the claw ring (12, 22) of the assembly unit (10, 20, 30, 40) a disc spring or a component designed similarly to a disc spring, a wave spring or an elastomer is assigned as a spring element (11 , 19, 21 , 31 , 41 ).

5. Steering column bearing (1 ) according to one of the preceding claims, characterized in that the axially aligned end-face segments (13, 23) of the assembly unit (10, 20, 30, 40) taper towards the outside towards the free end and, in the uninstalled state, have an inner diameter (Ds) which exceeds a diameter (DL) of the steering shaft (2).

6. Steering column bearing (1 ) according to one of the preceding claims, characterized in that the claw ring (12, 22) includes several curved claws (14) on the inside on the side facing away from the steering column bearing (1 ), which in the installed state are frictionally engaged on the steering shaft (2).

7. Steering column bearing (1 ) according to one of the preceding claims, characterized in that, for the purpose of retaining the assembly unit (10) securely, the spring element (11 ) has at least three circumferentially distributed, axially aligned connecting tabs (15) which rust into local recesses (16) of the claw ring (12) in a form-fitting and / or force-fitting manner.

8. Steering column bearing (1 ) according to one of the preceding claims, characterized in that the spring element (19) has cutouts (17) and / or retaining fingers (18) of the same or different design on the outside.

9. Steering column bearing (1) according to one of the preceding claims, characterized in that all components of the assembly unit (10, 20) are manufactured from a metallic material using a chipless forming process. are and the raceways (8, 9) of the outer bearing ring (5) and the inner bearing (4) for the rolling elements (7) of the steering column bearing (1) are honed.

10. Method for installing an assembly unit (10) according to the features of claims 1 to 9, wherein the method comprises the following steps: - Joining the previously individually manufactured components of the assembly unit (10) such as spring element (11) and claw ring (12) by means of a form-fit and / or force-fit connection; - Pressing the mounting unit (10) onto the steering shaft (2); - Moving the assembly unit (10) up to the steering column bearing (1); - Applying an axial force to the assembly unit (10) until the steering column bearing (1) is free of play and the assembly unit (10) is simultaneously fixed in position.

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