Swivel bearing for a motor vehicle wheel suspension

Abstract

Swivel bearing for a motor vehicle wheel suspension, comprising: one or more connection points for coupling wheel guide elements, and a wheel bearing receptacle (13) which is designed in the form of a ring (14) with an outer contour (15) and an inner contour (16), wherein the inner contour (16) defines a contact surface for a wheel bearing (20) which has a constant radius in the circumferential direction, wherein the outer contour (15) of the ring (14) has a non-roundness with respect to the contact surface of the inner contour (16), whereby the ring (14) has a wall thickness that varies in the circumferential direction, characterized by the fact that a bearing outer ring (21) of a wheel bearing (20) is pressed with the contact surface of the inner contour (16).

Description

[0001] The invention relates to a pivot bearing for a vehicle wheel suspension according to the preamble of claim 1.

[0002] Such a swivel bearing is known from DE 10 2010 023 232 A1. Further swivel bearings are known from DE 102011 016 628 A1, EP 1 314 630 A2 and DE 102 12 873 A1.

[0003] Swivel bearings, also known as wheel carriers or steering knuckles, connect a shock absorber or strut, a wheel bearing, a tie rod, and a ball joint on the front axle of a motor vehicle. Since swivel bearings are part of the vehicle's unsprung mass, there is a strong interest in making them as lightweight as possible. They are typically made of cast or forged steel, but can also be manufactured from light alloys. During driving, swivel bearings are subjected to stresses from shock absorber and / or spring forces, as well as wheel guidance forces. They must also absorb braking torques. These forces and torques, along with the installation situation, constitute the essential parameters for the design.

[0004] The invention is based on the objective of demonstrating solutions for further weight reduction.

[0005] This problem is solved according to the invention by a pivot bearing with the features according to claim 1. Further advantageous embodiments are specified in the dependent claims.

[0006] According to the present invention, a pivot bearing for a motor vehicle wheel suspension is provided. This comprises at least: one or more connection points for coupling wheel guide elements, and a wheel bearing mount which is designed in the form of a ring with an outer contour and an inner contour, wherein the inner contour defines a contact surface for a wheel bearing which has a constant radius in the circumferential direction, wherein the outer contour of the ring has a non-roundness in relation to the contact surface of the inner contour, causing the ring to have a wall thickness that varies in the circumferential direction.

[0007] The invention is characterized in that an outer bearing ring of a wheel bearing is pressed together with the contact surface of the inner contour.

[0008] By adjusting the wall thickness of the wheel bearing housing to the required support effect, material can be saved in the area of ​​the wheel bearing housing, thus reducing the overall component weight of the swivel bearing. Compared to a swivel bearing with a constant wall thickness at the wheel bearing housing, there is a weight saving potential of approximately 5 to 10%.

[0009] Depending on the connection of the wheel brake and the wheel guidance elements, which in this context generally include a damper or strut (if acting on the swivel bearing) and a tie rod, wall thicknesses and reductions must be adapted to the specific installation situation in the wheel suspension. The required wall thickness variations can be determined, for example, by analyzing the stresses and / or deformations of a corresponding swivel bearing with a constant wall thickness.

[0010] According to the invention, the swivel bearing is designed such that the outer ring of a wheel bearing is pressed against the contact surface of the inner contour. This enables simple and space-saving mounting of the wheel bearing and avoids stress concentrations induced by any fastening means.

[0011] Advantageous embodiments of the invention are the subject of further patent claims.

[0012] Preferably, the wheel bearing housing is designed such that sections of the ring with different wall thicknesses transition continuously into one another. This allows for good homogenization of the stresses occurring in the component under load.

[0013] Preferably, the sections of the ring with different wall thicknesses transition seamlessly into one another, thus avoiding local stress concentrations.

[0014] The wall thickness can be varied depending on one or more load cases, with areas under higher load having a greater wall thickness and areas under lower load having a smaller wall thickness. Defined load cases allow for a good representation of the stresses occurring during operation.

[0015] In principle, wall thickness variation can be based on a single load case, thus minimizing the coordination effort. However, preferably, a straight-line drive and at least one curve drive with defined curve parameters on a standardized vehicle are used as load cases for adjusting the wall thicknesses. Tests have shown that this approach yields good results.

[0016] According to an advantageous embodiment, the out-of-roundness of the outer contour is defined as the deviation from the mean radius of the outer contour. It amounts to 1 to 5% of the mean radius of the outer contour, where the mean radius is half the sum of the maximum and minimum radii of the outer contour. Although the wall thickness variation is relatively small, this can result in weight savings of approximately 140 g on a cast steel swivel bearing for a passenger vehicle.

[0017] According to a further advantageous embodiment of the invention, the ring of a swivel bearing for a left front wheel can be provided with an increased wall thickness at circumferential angles in the range of 80 to 110°, 170 to 210°, and 350 to 20°, wherein the circumferential angle is referenced to a 12 o'clock position in the installed position when viewed from the wheel side as the zero position. For the right front wheel, the arrangement of the areas with increased wall thickness is mirrored. This enables a favorable stress distribution in the wheel bearing housing both when driving straight ahead and when cornering.

[0018] The invention will now be explained in more detail with reference to an embodiment illustrated in the drawing. The drawing shows: Fig. 1 a spatial view of an embodiment of a swivel bearing according to the invention, Fig. 2 a detailed view of the wheel bearing mount in section with the wheel bearing installed, and in Fig. 3 different variants a to c of wheel bearing mounts according to the invention with varying wall thickness as well as in d a wheel bearing mount with constant wall thickness.

[0019] The embodiment shows a swivel bearing 1 for a wheel suspension of a motor vehicle using the example of a front axle of a passenger car.

[0020] The swivel bearing 1 acts as a connecting link between a damper or strut, a wheel bearing, a tie rod, and a ball joint. However, a different configuration of the vehicle-side interfaces is also possible.

[0021] To couple the aforementioned components, the swivel bearing 1 of the exemplary embodiment forms various connection sections, which are integrated in this case into a one-piece component.

[0022] A substantially cylindrical sleeve section 10 serves as the damper or strut mount. The sleeve section 10 has a longitudinal slot on one side facing away from the wheel, as well as a clamping device molded onto the outer circumference of the sleeve section. The latter allows the sleeve halves to be clamped together to secure, for example, an end section of a damper reservoir tube. In the pivot bearing's installed position, the longitudinal axis A of the sleeve section 10 can be angled at up to 10 degrees to the vertical direction B.

[0023] The sleeve section 10 is connected via webs 11 to a central section 12, which has a wheel bearing receptacle 13. The wheel bearing receptacle 13 forms a ring 14 with an outer contour 15 and an inner contour 16. The radial distance between the outer contour 15 and the inner contour 16 represents the wall thickness of the ring 14.

[0024] The inner contour 16 of the ring 14 defines a contact surface for a wheel bearing 20, which is in Fig. Figure 3 is shown. Its axis of rotation C is perpendicular to the vertical direction B.

[0025] The wheel bearing 20 has a one-piece outer bearing ring 21, which is axially pressed into the inner contour 16 of the wheel bearing receptacle 13. Furthermore, the two-track wheel bearing 20 has two inner bearing rings, namely a wheel-side inner bearing ring 22 and a gearbox-side inner bearing ring 23, which are fixed to a wheel hub 30.

[0026] Furthermore, the swivel bearing 1 has a tie rod connection arm 17 which, with respect to the vertical direction B in the installed position, projects from the central section 12 below the axis of rotation C of the wheel bearing 20 in the opposite direction of forward travel and has a coupling point 17a at its end for coupling a tie rod. The tie rod connection arm 17 can be formed by several webs 17b, which form a lattice structure with several openings 17c.

[0027] On the side opposite the tie rod connection arm 17, the central section 12 has two projections 18, which serve for the attachment of a brake caliper. Each projection 18 can form an eye 18a at its free end, which is connected to the central section via two webs 18b and 18c. An opening 18d can be provided between the webs 18b and 18c. One of the projections 18 can be arranged vertically above, and the other below, the axis of rotation C.

[0028] The pivot bearing 1 further comprises a guide joint connection section 19 for coupling a wheel control arm. The guide joint connection section 19 is arranged below the wheel bearing receptacle 13 with respect to the installation position on the vehicle and has a coupling point 19a for coupling a corresponding joint of the wheel control arm.

[0029] To reduce the component weight of the swivel bearing 1, the ring 14 of the wheel bearing receptacle 13 has a varying wall thickness. However, the inner contour 16, which defines the contact surface for the wheel bearing 20, has a constant radius in the circumferential direction. The contact surface is therefore circular in the circumferential direction.

[0030] The wall thickness variation of the ring 14 is achieved solely by shaping the outer contour 15, so that it has a non-roundness.

[0031] This non-roundness and the associated variation in wall thickness are implemented depending on one or more load cases, with areas under higher load having a greater wall thickness and areas under lower load having a smaller wall thickness. This results in a load-dependent variation in wall thickness.

[0032] The respective areas can be determined, for example, using finite element methods or experimentally. They depend on the individual configuration of the respective swivel bearing type and cannot be generalized. However, it is essential that the load-dependent wall thickness variation on the ring 14 of the wheel bearing housing 13 results in a reduction of the overall component weight on the order of approximately 5 to 10% compared to a ring 14' with a constant wall thickness from the prior art, as described in [reference to prior art]. Fig. 3D representation can be achieved without compromising the load-bearing capacity of the swivel bearing 1.

[0033] One way to adjust the wall thickness variation in the circumferential direction is to define circumferential node lines on the outer bearing ring 21 in the area of ​​the wheel-side and gearbox-side rolling element raceways. Finite element methods are then used to determine the displacements of the nodes along these lines for predefined load cases. The radial displacement relative to the initial position is then determined for each node. From this, the roundness deviations for the respective load case, dependent on the rotation angle φ, are derived. For a left-hand swivel bearing, the circumferential angle φ is referenced to a zero position in the mathematical direction of rotation, which corresponds to the 12 o'clock position in the installed position when viewed from the wheel side. This is mirrored for the right-hand swivel bearing.

[0034] In this way, for a ring 14 with a constant wall thickness, the circumferential regions with the largest radial displacements can be determined, and the wall thickness can be increased at these points, while in regions of the smallest radial displacements, the wall thickness can be reduced. If this process is repeated several times, the desired wall thickness profile for the ring 14 of the wheel bearing housing 13, as a function of the circumferential angle φ, is obtained for the respective swivel bearing 1.

[0035] The observed wall thickness profile can be smoothed so that sections of ring 14 with different wall thicknesses transition seamlessly into one another. Furthermore, the wall thickness profile can be designed to be continuous in the circumferential direction to avoid stress concentrations.

[0036] The wall thickness profile can be adjusted depending on a single load case. Fig. Figure 3a shows a wall thickness profile that is optimized for straight-line driving. Fig. Figure 3b shows another wall thickness profile, which is tailored to a defined cornering maneuver, i.e., driving through a curve with a standardized vehicle at a predetermined speed and curve radius. As can be clearly seen, different wall thickness profiles result here.

[0037] Fig. Figure 3c shows a wall thickness profile that is optimized for both of the aforementioned load cases, i.e., straight-line driving and cornering with defined curve parameters. During optimization, both load cases can be weighted equally or differently. Furthermore, it is possible to include additional load cases in the optimization.

[0038] Other parameters can also be used to determine the wall thickness variation, which correlate significantly with the load in the ring 14 of the wheel bearing mount 13.

[0039] In particular, a procedure based on determining the stresses occurring in ring 14 under one or more load cases is also possible.

[0040] The resulting out-of-roundness of the outer contour 15 can be understood as a deviation from the mean radius of the outer contour 15. It is on the order of 1 to 5% of the mean radius, where the mean radius is half the sum of the maximum and minimum radii of the outer contour 15.

[0041] For the in Fig. 1. The swivel bearing 1 of a left front wheel shown results in increased wall thicknesses when adjusted for straight-line driving and cornering at circumferential angles φ at least in the ranges of 80 to 110°, 170 to 210° and 350 to 20°.

[0042] It is understood that with a different design of the brake, damper, tie rod, and guide joint connections, the areas of increased and reduced wall thickness may be distributed differently in the circumferential direction. The respective wall thickness profile can be determined for each swivel bearing type using the procedure described above. In all cases, the variation in wall thickness and the circumferential non-roundness of the outer contour 15 of the wheel bearing housing 14 result in a weight-saving potential, which allows the unsprung mass of a motor vehicle to be reduced without compromising load-bearing capacity.

[0043] The invention has been explained in more detail above with reference to an exemplary embodiment. However, it is not limited to this exemplary embodiment, but encompasses all embodiments defined by the claims. Reference symbol list 1 swivel bearing 10 sleeve section 11 Bridge 12 Middle section 13 Wheel bearing mount 14 rings 15 Outer contour 16 Inner contour 17 Tie rod end arm 17a Coupling point 17b Bridge 17c Breakthrough 18 lead to wheel brake coupling 18a Eye 18b Bridge 18c Bridge 18d breakthrough 19 Guide joint connection section 19a Coupling point 20 wheel bearings 21 Outer bearing ring 22 wheel-side inner bearing ring 23 Gearbox-side inner bearing ring 30 wheel hub A damper axle B Vertical direction C axis of rotation of the wheel bearing D Horizontal φ circumferential angle

Claims

[1] Swivel bearing for a motor vehicle wheel suspension, comprising: one or more connection points for coupling wheel guide elements, and a wheel bearing receptacle (13) which is designed in the form of a ring (14) with an outer contour (15) and an inner contour (16), wherein the inner contour (16) defines a contact surface for a wheel bearing (20) which has a constant radius in the circumferential direction, wherein the outer contour (15) of the ring (14) has a non-roundness with respect to the contact surface of the inner contour (16), whereby the ring (14) has a wall thickness that varies in the circumferential direction, characterized by , that a bearing outer ring (21) of a wheel bearing (20) is pressed with the contact surface of the inner contour (16). [2] Swivel bearing according to claim 1, characterized by , that sections of the ring (14) with different wall thicknesses continuously merge into one another. [3] Swivel bearing according to claim 1 or 2, characterized by , that sections of the ring (14) with different wall thicknesses transition seamlessly into one another. [4] Swivel bearing according to any one of claims 1 to 3, characterized by , that the variation of the wall thickness is made depending on one or more load cases, with areas with higher load having a greater wall thickness and areas with lower load having a smaller wall thickness. [5] Swivel bearing according to claim 4, characterized by , that the load cases are a straight-ahead journey and at least one curve journey with defined curve parameters on a standardized vehicle. [6] Swivel bearing according to any one of claims 1 to 5, characterized by, that the out-of-roundness of the outer contour (15) is defined as the deviation from the mean radius of the outer contour (15) and is 1 to 5% of the mean radius, where the mean radius is half the sum of the maximum and minimum radii of the outer contour (15). [7] Swivel bearing according to any one of claims 1 to 6, characterized by , that on a swivel bearing for a left front wheel the ring has an increased wall thickness at a circumferential angle in the range of 80 to 110°, at a circumferential angle in the range of 170 to 210°, and at a circumferential angle in the range of 350 to 20°, wherein the circumferential angle in the mathematical direction of rotation is referred to a 12 o'clock position in the installation position when viewed from the wheel side as the zero position.

Images