Wheel bearing comprising raceway for improving rigidity at the zero crossing point

Abstract

The invention relates to a wheel bearing (1) for a motor vehicle, said bearing having a bearing element (2) with a raceway (4a, 4b) which accommodates a plurality of rolling elements (3), wherein at least some portions of the raceway (4a, 4b) deviate from a circular line of constant diameter.

Description

[0001] Wheel bearing with raceway for stiffness improvement in zero passage

[0002] The invention relates to a wheel bearing for a motor vehicle, for example a car, truck, bus or other commercial vehicle, comprising a bearing element with a raceway accommodating several rolling elements. The rolling elements are thus mounted on the raceway in a rolling / rolling manner (usually spaced apart from each other in the circumferential direction).

[0003] Wheel bearings of the type used, as rolling bearings, are already well known from the prior art. It has generally been shown that for vehicles, it is desirable to achieve the most stable directional handling possible, even with small steering movements. This, in turn, requires relatively high bearing stiffness, especially when driving straight ahead. This bearing stiffness can be achieved, for example, by increasing the bearing preload, which brings more rolling elements into contact simultaneously. However, this in turn leads to an increase in bearing friction.

[0004] The object of the present invention is therefore to provide a wheel bearing in which the bearing stiffness at zero crossing is increased without significantly increasing the bearing friction.

[0005] This is solved according to the invention by the fact that the raceway deviates, at least in sections, from a circle of constant diameter.

[0006] This results in a more rolling element engaging at the zero crossing of the bearing tilt, preferentially in the outer ring, due to a targeted deviation of the raceway from a circular path (e.g., an ovality). This makes it possible to increase bearing stiffness at the zero crossing while simultaneously minimizing bearing friction. The zero crossing describes the state when the lateral forces acting on the bearing change direction, i.e., during small left / right steering movements in the vehicle.

[0007] Further advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0008] It has proven to be a particularly efficient solution if the track is advantageously elliptical / oval, at least in sections.

[0009] In a further preferred embodiment, it is advantageous if the entire raceway is completely elliptical / entirely formed as an ellipse / or revolves around the entire surface. It is also possible that the raceway is composed of at least two elliptical halves that transition discontinuously (but preferably continuously) into each other at their ends.

[0010] It is also advantageous if, viewed in the intended installation position, the lower half of the track is elliptical, while the upper half of the track is circular.

[0011] Alternatively, it is also advantageous if, viewed in the intended installation position, the upper half of the raceway is elliptical, while the lower half of the raceway is circular.

[0012] It has also proven advantageous if the ovality of the raceway is designed such that it deviates from a circle of constant diameter by a (maximum) diameter of 5 pm to 30 pm, preferably 10 pm to 20 pm, at a specific point on its circumference. This circle forms a diameter that the raceway directly exhibits, at least in sections. Furthermore, it is advantageous if the ovality of the raceway is designed to be asymmetrical with respect to a horizontal axis. This also minimizes bearing friction while achieving the most stable steering behavior possible.

[0013] This effect is further increased if, advantageously, two (axially offset) raceways (for two rolling bearing groups) are present on the bearing element, each of which deviates at least partially from a circle of constant diameter.

[0014] It has also proven advantageous if the bearing element is designed as an outer ring.

[0015] Preferably, the bearing element is also designed as a bearing flange, i.e., with a flange area.

[0016] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are also shown.

[0017] They show:

[0018] Fig. 1 shows a schematic longitudinal section view of a bearing according to the invention in a first embodiment,

[0019] Fig. 2 shows a longitudinal section view of a bearing element used in Fig. 1, designed as a standing outer ring, having two raceways, each of which is implemented with an ovality (section by section),

[0020] Fig. 3 shows a cross-sectional view of the bearing element of Fig. 2 along the section line marked “III-IH” in Fig. 2, wherein the raceway to be seen has an ovality, particularly in its upper half; Fig. 4 shows a cross-sectional view of a bearing element of a wheel bearing according to a second embodiment, in which the lower half now has the ovality.

[0021] Fig. 5 shows a cross-sectional view of a bearing element of a wheel bearing according to a third embodiment, wherein the entire raceway is now realized as a continuous oval shape, as well as

[0022] Fig. 6 shows a cross-sectional view of the bearing element of Fig. 3, illustrating a preferred manufacturing technique for the raceway.

[0023] The figures are purely schematic and serve solely to illustrate the invention. The same elements are identified by the same reference symbols.

[0024] Figure 1 illustrates the basic structure of a wheel bearing 1 according to the invention. The wheel bearing 1 is designed in the usual way as a wheel bearing 1 of a motor vehicle and is accordingly used in the area of ​​a tire-equipped wheel of the motor vehicle for supporting the wheel.

[0025] The wheel bearing 1 is implemented as a rolling bearing, here in the form of a double-row ball bearing. In other embodiments, however, the wheel bearing 1 can also be implemented as a different type of rolling bearing.

[0026] An axis of rotation 9, also visible in Fig. 1, simultaneously forms the reference axis for the directional terms used here: axial, radial, and circumferential. Axial direction is therefore understood to mean a direction along or parallel to the axis of rotation 9, radial direction a direction perpendicular to this axis of rotation 9, and circumferential direction a direction along an imaginary circle that rotates concentrically around the axis of rotation 9. The wheel bearing 1 has a bearing element 2, which can also be called a bearing flange and has a flange area 8 on its radial outer surface. The bearing element 2 also directly forms an outer ring of the wheel bearing 1.Due to the design of the wheel bearing 1 as a double-row rolling bearing, the bearing element 2 has two axially spaced raceways 4a, 4b, each of which in turn has several rolling elements 3 distributed in the circumferential direction / rolling elements 3.

[0027] Two radially arranged inner ring areas 10a, 10b of the wheel bearing 1 are realized in a conventional two-part manner to enable assembly of the wheel bearing 1.

[0028] Figures 2 and 3 further illustrate an embodiment of the respective raceways 4a and 4b according to the invention. It should be noted that, for the sake of brevity, only the embodiment of the first raceway 4a is described below. This is because the second raceway 4b is preferably designed / constructed in accordance with the first raceway 4a, with the only difference being that they are symmetrical to each other with respect to an axially arranged plane of symmetry between them. The following explanations regarding the structure and function of the first raceway 4a therefore also apply to the second raceway 4b.

[0029] Figure 3, viewed in cross-section, clearly shows that the (first) raceway 4a is intentionally designed with a shape that deviates from a circle / circle of constant diameter. In the first embodiment, the first raceway 4a is at least partially elliptical / oval in its upper half 6. A lower half 5, on the other hand, has a constant diameter and is thus realized as a circle of constant diameter. The lower half 5 and the upper half 6 are to be considered here in relation to the gravitational field acting during operation, in their intended installation position. The lower half 5 and the upper half 6 are essentially separated from each other by a drawn horizontal axis 7. In the first embodiment, the upper and lower halves 5, 6 of the first raceway 4a thus connect with a region that replicates the circle of constant diameter.

[0030] Figures 4 and 5 illustrate that, in principle, it is also possible in further embodiments to design the respective (first or second) raceway 4a, 4b differently, with the further structure and further functioning of these alternative embodiments corresponding to the first embodiment. For the sake of brevity, only the differences between the individual embodiments are described below.

[0031] Figure 4 illustrates that, as an alternative to shaping the upper half 6 as an ellipse / oval, it is also possible to shape the lower half 5 as an oval / elliptical shape. In this case, the upper half 6 is again implemented with a constant diameter / as a circle of constant diameter.

[0032] In conjunction with Figures 3 and 4, it should also be noted that the deviation from the circle of constant diameter shown at the lowest / uppermost point of the track 4a is at its maximum. This deviation, labeled Q, is preferably between 5 pm and 30 pm, more preferably between 10 pm and 20 pm, here approximately 15 pm. This deviation Q is at its maximum at the indicated point and decreases continuously towards the edges, i.e., towards the horizontal axis 7 (upwards or downwards).

[0033] In the third embodiment shown in Fig. 5, it further becomes clear that it is also possible, in principle, to realize the entire raceway 4a as an ellipse. Here, it is possible to realize the contact areas / transition zone between the two halves 5, 6 as continuous or discontinuous. It is indicated that the deviations from the circle of constant diameter, both with respect to the lower half 5 and the upper half 6, as well as at the transitions between the lower and upper halves 5, 6 in the region of the horizontal axis 7, each amount to one quarter of the deviation Q of the embodiments shown in Figs. 3 and 4. Fig. 6 further illustrates that it is preferable to form the different ellipses / ovalities visible in Figs. 3 to 5 using a CNC grinding process. For example, a so-called oval grinding of the raceways 4a, 4b is implemented.The outer ring, in the form of bearing element 2, can be clamped in an oval shape, either before or during grinding, to achieve the desired ovality after grinding and subsequent stress relief. Clamping is preferably carried out using a clamping tool.

[0034] It is also possible in principle to press the outer ring / bearing element 2 into an oval shape by screwing it onto the steering knuckle or wheel carrier with a suitably appropriate shape.

[0035] It is also possible to manufacture the outer ring / bearing element 2 with a specific oval shoe diameter in order to achieve a targeted ovality in the raceway 4a, 4b after grinding. The shape of the shoe running surface is transferred to the grinding surface during shoe grinding.

[0036] In other words, according to the invention, a targeted ovality of the raceways 4a, 4b in the outer ring or on the non-rotating bearing part is created in order to get more rolling elements into engagement at the zero crossing of the bearing tilt.

[0037] Asymmetrical ovality, referring to the geometric shape of the ovality, is also conceivable.

[0038] Similarly, ovality can also be present on only one side of the track (only first track 4a or second track 4b). Reference symbol list

[0039] wheel bearing

[0040] bearing element

[0041] Rolling element a first raceway b second raceway lower half upper half

[0042] Horizontal axis

[0043] Flange area

[0044] axis of rotation 0a first interior area 0b second interior area

Claims

Patent claims 1. Wheel bearing (1) for a motor vehicle, comprising a bearing element (2) having a raceway (4a, 4b) accommodating several rolling elements (3), characterized in that the raceway (4a, 4b) deviates at least in sections from a circle of constant diameter.

2. Wheel bearing (1 ) according to claim 1 , characterized in that the raceway (4a, 4b) is at least partially elliptical.

3. Wheel bearing (1 ) according to claim 1 or 2, characterized in that the entire raceway (4a, 4b) is fully elliptical.

4. Wheel bearing (1 ) according to one of claims 1 to 3, characterized in that a lower half (5) of the raceway (4a, 4b) viewed in the intended installation position is elliptical, while an upper half (6) of the raceway (4a, 4b) is circular.

5. Wheel bearing (1 ) according to one of claims 1 to 4, characterized in that an upper half (6) of the raceway (4a, 4b) when viewed in the intended installation position is elliptical, while a lower half (5) of the raceway (4a, 4b) is circular.

6. Wheel bearing (1 ) according to one of claims 1 to 5, characterized in that the ovality of the raceway (4a, 4b) is designed such that it deviates at one point by a diameter dimension of 5pm to 30pm from a circle of constant diameter.

7. Wheel bearing (1 ) according to one of claims 1 to 6, characterized in that the ovality of the raceway (4a, 4b) is designed such that it is asymmetrical with respect to a horizontal axis (7).

8. Wheel bearing (1) according to one of claims 1 to 7, characterized in that two raceways (4a, 4b) are provided on the bearing element (2) which each deviates, at least in sections, from a circle of constant diameter.

9. Wheel bearing (1 ) according to one of claims 1 to 8, characterized in that the bearing element (2) is designed as an outer ring.

10. Wheel bearing (1 ) according to one of claims 1 to 9, characterized in that the bearing element (2) also has a flange area (8).

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