Sealing arrangement for wheel bearings and wheel bearing unit with sealing arrangement

Description

[0001] The present invention relates to a sealing arrangement for a wheel bearing, a use of such a sealing arrangement for sealing a wheel bearing and a wheel bearing unit with such a sealing arrangement. State of the art

[0002] Seals for bearings, such as rolling bearings, plain bearings, etc., are well known. They are designed to prevent dirt from entering the bearing and, if necessary, prevent lubricant from escaping from the bearing, ensuring the longest possible service life.

[0003] In the case of wheel bearings with rolling elements, a sliding seal on both sides of the space filled with lubricant that accommodates the raceways and rolling elements must be used to ensure that neither solid particles nor corrosive media can penetrate into this space. Since slight tilting can occur within the bearing during driving, e.g. during lateral acceleration, there is a risk that conventional seals, in particular so-called lip seals, will lift off from the sliding surfaces, allowing solid particles, e.g. dirt or dust, to penetrate the bearing. These conventional seals can also work together with a so-called flinger plate, which is made from formed sheet metal. The flinger plate is usually connected to a rotating wheel hub orIt is connected to a rotating wheel bearing flange and, together with another sheet metal ring arranged in a stationary part of the wheel suspension, can form an additional sealing labyrinth. The sealing lips of at least one sealing ring extend in the axial or radial direction and are guided in a sliding manner on the flinger plate. The aforementioned components of the seal can also be an integral part of a seal cassette in which the sealing lips are axially preloaded in a defined manner.

[0004] On both sides of the wheel bearing there is a mainly axially directed opening between the two rotating partners, which are coupled to each other by the wheel bearing. The opening on the vehicle side in the axial direction is essentially axially directed and is occasionally covered by a joint bell of an adjacent constant velocity joint. The opening on the wheel flange side in the axial direction is directed radially outwards due to the immediately adjacent wheel bearing flange and is therefore very easily accessible for splash water, for example. In order to improve the sliding sealing contact present on the wheel bearing flange, the flinger plate made of formed sheet metal is inserted onto the wheel bearing flange adjacent to the wheel bearing flange before the wheel bearing is installed on the wheel hub.

[0005] DE 11 2010 000730 T5 shows a generic sealing arrangement.

[0006] During vehicle operation, shock, continuous vibration loads or other causes can cause the flinger to slip, causing the flinger to move towards the rolling elements and damage them upon contact, leading to wheel bearing failure.

[0007] It is an object of the present invention to provide an improved sealing arrangement for a wheel bearing, which in particular seals reliably over the service life and has a longer service life. Disclosure of the invention

[0008] This object is achieved by a sealing arrangement for a wheel bearing according to the independent claims. Advantageous embodiments and further developments can be found in the dependent claims and the following description.

[0009] The sealing arrangement according to the invention for a wheel bearing comprises a carrier element, an elastic sealing element, and a counter-rotating plate. The carrier element can be connected to a first bearing part of the wheel bearing. The elastic sealing element has an elastic main body arranged on the carrier element. Furthermore, the elastic sealing element has at least a first axial sealing lip, a second axial sealing lip, and at least one radial sealing lip extending away from the elastic main body. The counter-rotating plate can be connected to a second bearing part and is arranged with one side facing the carrier element such that the first axial sealing lip, the second axial sealing lip, and the radial sealing lip are in sliding contact with the counter-rotating plate. The first axial sealing lip is designed such that it bears against the counter-rotating plate with a first contact force.The second axial sealing lip is designed to bear against the mating plate with a second contact pressure. The radial sealing lip is designed to bear against the mating plate with a third contact pressure. The contact pressures are defined as a function of a predetermined force ratio.

[0010] The advantage of the solution according to the invention lies in the fact that it reliably prevents the sealing lips from lifting off the counter-rotating plate. This lifting of the sealing lips is reliably prevented under all pressure conditions that can usually occur within the sealing arrangement during operation. Furthermore, contact between the two axial sealing lips can be avoided. The predetermined force ratio defines the contact forces such that the contact forces of the axial sealing lips prevent the sealing lubricant, e.g. grease, from escaping from a sealing chamber, and the contact force of the radial sealing lip prevents the bearing lubricant, e.g. bearing grease, from escaping from the bearing. As a result, the sealing arrangement according to the invention can be reliably used even in very tight installation spaces.

[0011] According to the invention, the predetermined force ratio is defined by the following equations: erste Anpresskraft = zweite Anpresskraft ± 0 , 9 N dritte Anpresskraft = 0 , 5 * erste Anpresskraft ± 0 , 9 N

[0012] The contact forces of the two axial sealing lips are essentially equal. The contact force of the radial sealing lip is essentially half the contact force of the axial sealing lips to reduce friction between the radial sealing lip and the counter-rotating plate, thus facilitating sliding between the radial sealing lip and the counter-rotating plate without reducing sealing performance. The tolerance range for the design of the contact forces is approximately ± 0.9 N.

[0013] According to one embodiment, the main body of the elastic sealing element is arranged at least in the region of the axial sealing lips in the axial direction at a first axial distance from the counter-running plate.

[0014] The first axial distance defines a clearance, the sealing space, formed between the main body and the counter-rotating plate, which serves to accommodate the sealing lubricant. Furthermore, the first and second axial sealing lips extend through this clearance to the counter-rotating plate to prevent the sealing lubricant from escaping from the clearance and prevent dirt from entering the clearance. The first axial distance is selected depending on the available installation space for the sealing arrangement and can, for example, be equal to or greater than 1.7 mm, alternatively equal to or greater than 1.95 mm, or even equal to or greater than 2.0 mm.

[0015] According to one embodiment, the first axial sealing lip and the second axial sealing lip further have a first radial distance from one another in the radial direction on the counter-rotating plate and a second radial distance from one another on the carrier element, wherein the first radial distance and the second radial distance are defined as a function of the first axial distance.

[0016] The design of the first and second radial distances as a function of the first axial distance makes it possible to reliably avoid contact between the first axial sealing lip and the second axial sealing lip in the assembled and operating state. The first radial distance is preferably greater than the second radial distance and can, for example, be 1.24 times, 1.15 times, or 1.03 times the first axial distance. The second radial distance can, for example, be the quotient of the first axial distance as the dividend and 1.27, 1.45, or 1.59 as the divisor. In other words, the second radial distance can, for example, be approximately 0.787 times, 0.69 times, or 0.629 times the first axial distance.

[0017] According to one embodiment, the first axial sealing lip on the main body has a first radial thickness in the radial direction, and the second axial sealing lip on the main body has a second radial thickness in the radial direction, wherein the first radial thickness and the second radial thickness are defined as a function of the second radial distance. Since the second radial distance is defined as a function of the first axial distance, the first radial thickness and the second radial thickness can also be defined as a function of the first axial distance.

[0018] The design of the first and second radial thicknesses as a function of the second radial distance and the first axial distance, respectively, makes it possible to reliably prevent contact between the first axial sealing lip and the second axial sealing lip in the assembled and operating states. The first radial thickness is preferably approximately equal to or slightly smaller than the second radial thickness and can be, for example, 0.50 times, 0.40 times, or 0.38 times the second radial distance. The second radial thickness can be, for example, 0.50 times, 0.45 times, or 0.40 times the second radial distance.

[0019] According to a preferred embodiment, the first axial sealing lip and the second axial sealing lip are arranged obliquely with respect to a rotation axis of the wheel bearing, wherein a diameter of the sealing lips increases in the axial direction from the main body to the counter-running plate.

[0020] An inclined position of the axial sealing lips relative to the rotational axis makes it more difficult for them to lift off the counter-rotating plate during operation, thus ensuring the seal's sealing performance under the pressure conditions typically encountered during operation. Furthermore, the inclined position of the axial sealing lips prevents contact between the sealing lips during sealing, especially in very tight installation spaces.

[0021] According to the invention, an inner circumferential surface of the first axial sealing lip is arranged with a first inner circumferential surface angle to the rotation axis and an outer circumferential surface of the first axial sealing lip is arranged with a first outer circumferential surface angle to the rotation axis, wherein the first outer circumferential surface angle is defined as a function of the first inner circumferential surface angle.

[0022] According to the invention, an inner circumferential surface of the second axial sealing lip is arranged with a second inner circumferential surface angle to the rotation axis and an outer circumferential surface of the second axial sealing lip is arranged with a second outer circumferential surface angle to the rotation axis, wherein the second outer circumferential surface angle is defined as a function of the second inner circumferential surface angle.

[0023] This means that the thickness of the axial sealing lips changes from the carrier element all the way to the counter-rotating plate. This supports or reinforces the effect of avoiding contact between the two axial sealing lips, which is already achieved by the inclination of the two axial sealing lips in relation to the axis of rotation. If the two axial sealing lips touch, leakage of the sealing lubricant from the sealing chamber can no longer be reliably prevented. Therefore, contact between the two axial sealing lips must be avoided. If the first inner circumferential surface angle is, for example, between 25° and 28°, the first outer circumferential surface angle is, for example, 4.7° greater than the first inner circumferential surface angle, with a tolerance of ±1°. Furthermore, the first inner circumferential surface angle can be, for example, between 33° and 36°. In this case, the first outer circumferential surface angle is, for example,0.553° to 0.58° smaller than the first inner peripheral surface angle, with a tolerance of ±1°.

[0024] If the second inner peripheral surface angle is, for example, between 30° and 33°, the second outer peripheral surface angle is, for example, 5.1° greater than the second inner peripheral surface angle, with a tolerance of ±1°. Furthermore, the second inner peripheral surface angle can be, for example, between 36° and 39°. Then the second outer peripheral surface angle is, for example, 0.335° to 0.352° smaller than the second inner peripheral surface angle, with a tolerance of ±1°.

[0025] According to one embodiment, a third axial sealing lip is further provided, which serves as a pre-seal. The pre-seal does not extend to the counter-rotating plate and creates a trapping labyrinth designed to directly expel penetrating solid particles back to the outside, thereby protecting the axial sealing lips from dirt or dirty water.

[0026] Further aspects of the invention relate to the use of a sealing arrangement described above for sealing a wheel bearing and to a wheel bearing unit for a motor vehicle, comprising a wheel bearing and a sealing arrangement described above. Detailed description based on drawing

[0027] Further measures improving the invention are described in more detail below, together with the description of a preferred embodiment of the invention, with reference to the figures. It shows: Fig. 1 shows a schematic longitudinal sectional view of a wheel flange-side sealing arrangement according to one embodiment of the invention. Fig. 2 shows a schematic longitudinal sectional view of a vehicle-side sealing arrangement according to one embodiment of the invention. Fig. 3 shows a schematic longitudinal sectional view of a wheel flange-side sealing arrangement according to another embodiment of the invention.

[0028] The figures are merely schematic and serve only to clarify the invention. Identical elements are designated by the same reference numerals.

[0029] Fig. 1 shows a sealing arrangement 1 arranged in the axial direction A between a wheel bearing 2 and a wheel bearing flange 3, with both the wheel bearing 2 and the wheel bearing flange 3 being shown only in sections. The wheel bearing 2 is designed as a rolling bearing with rolling elements 4, which are supported by a cage 5 in rolling raceways of bearing rings 6 enclosing the rolling elements 4.

[0030] The sealing arrangement 1 has a carrier element 7, which is attached to one of the bearing rings 6 by a fastening section 8. An elastic sealing element 9 is arranged on the carrier element 7 and has an elastic main body 10, from which a first axial sealing lip 11, a second axial sealing lip 12, and a radial sealing lip 13 extend. The sealing arrangement 1 also has a counter-rotating plate 14, which is arranged facing the carrier element 7 such that it is in sliding contact with the axial sealing lips 11, 12 and the radial sealing lip 13. The counter-rotating plate 14 is attached by a fastening section 15 to the wheel bearing flange 3, which is formed integrally with the other of the bearing rings 6 (not shown here).In addition, an elastic sealing element 16 is arranged on the counter-running plate 14 in the region of the fastening section 15, which seals a coupling point between the fastening section 15 and the wheel bearing flange 3.

[0031] The sliding contact is illustrated by the overlapping representation of the sealing lips 11, 12, 13 with the counter-rotating plate 14. In practice, the sealing lips 11, 12, 13 do not overlap with the counter-rotating plate 14, but rather rest against the counter-rotating plate 14 in such a way that, upon a rotational movement of the wheel bearing flange 3—and thus of the counter-rotating plate 14—a sliding contact develops between the sealing lips 11, 12, 13 and the counter-rotating plate 14. The sliding contact is individual for each of the sealing lips 11, 12, 13 and is defined by the fact that the sealing lips 11, 12, 13 each rest against the counter-rotating plate 14 with a predetermined contact force F.

[0032] The first axial sealing lip 11 bears against the counter-rotating plate 14 with a first contact force F 1 and the second axial sealing lip 12 with a second contact force F 2 . The radial sealing lip 13 bears against the counter-rotating plate 14 with a third contact force F 3 , wherein the first and second contact forces F 1 , F 2 are applied in the axial direction A and the third contact force F 3 is applied in the radial direction R.

[0033] The contact forces F 1 , F 2 and F 3 are in a predetermined force ratio to each other, which defines the contact forces F 1 , F 2 , F 3 in dependence on each other as follows: F 1 = F 2 ± 0 , 9 N 1 und F 3 = 0 , 5 * F 1 ± 0 , 9 N 2

[0034] The information ± 0.9 N indicates a tolerance range for calculating the forces.

[0035] The counter-rotating plate 14 is arranged at a first axial distance I A1 from the support element 7 with the elastic main body 10 in the axial direction A, so that a free space, i.e., a sealing space 17, is formed. The axial sealing lips 11, 12 extend substantially obliquely in the axial direction A through the sealing space 17 to the counter-rotating plate 14 and are spaced apart from one another in the radial direction R, wherein the first axial sealing lip 11 is arranged further inward in the radial direction R than the second axial sealing lip 12.

[0036] The distance between the two axial sealing lips 11, 12 is not constant over their length, i.e., a first radial distance I R1 between the first axial sealing lip 11 and the second axial sealing lip 12 on the counter-rotating plate 14 differs from a second radial distance I R2 between the first axial sealing lip 11 and the second axial sealing lip 12 on the carrier element 7. Both the first radial distance I R1 and the second radial distance I R2 are defined as a function of the first axial distance I A1. In the embodiment shown in this figure, the first axial distance I A1 is, for example, greater than or equal to 1.7 mm, and the first radial distance I R1 and the second radial distance I R2 are defined, for example, as follows: I R 1 = I A 1 * 1 , 24 3 und I R 2 = I A 1 / 1 , 27 4 .

[0037] In addition, the first axial sealing lip 11 on the carrier element 7 has a first radial thickness d R1 , and the second axial sealing lip 12 has a second radial thickness d R2 on the carrier element 7. The two radial thicknesses d R1 , d R2 are in turn defined as a function of the second radial distance I R2 and are thus also defined as a function of the first axial distance I A1 : d R 1 = I R 2 * 0 , 38 = I A 1 / 1 , 27 * 0 , 38 5 , und d R 2 = I R 2 * 0 , 4 = I A 1 / 1 , 27 * 0 , 4 6 .

[0038] Furthermore, the thickness of the axial sealing lips 11, 12 also changes along their direction of extension. This change in thickness is specified by a ratio between an inner circumferential surface angle and an outer circumferential surface angle of the respective axial sealing lip 11, 12. The inner circumferential surface angle is an angle between an inner circumferential surface of the respective axial sealing lip 11, 12 and a rotational axis (not shown) of the sealing arrangement 1, and the outer circumferential surface angle is an angle between an outer circumferential surface of the respective axial sealing lip 11, 12 and the rotational axis of the sealing arrangement 1. The outer circumferential surface angle is dependent on the inner circumferential surface angle.

[0039] Thus, in the Fig. 1In the embodiment shown, a first inner circumferential surface angle α 1 of the first axial sealing lip 11 is between 33° and 36°. A second inner circumferential surface angle β 1 of the second axial sealing lip 12 is between 36° and 39°. A first outer circumferential surface angle α 2 and a second outer circumferential surface angle β 2 are then defined as follows: α 2 = α 1 − 0 , 553 ° ± 1 ° 7 bzw . β 2 = β 1 − 0 , 342 ° ± 1 ° 8

[0040] The specification ± 1° indicates a tolerance range for the design of the angles.

[0041] It can therefore be seen that the sealing arrangement 1 is designed, on the one hand, based on the contact pressure of the sealing lips 11, 12, 13 on the counter-rotating plate 14 and, on the other hand, as a function of the first axial distance I A1 . The first axial distance I A1 is directly related to the installation space available for the sealing arrangement 1. This means that the sealing arrangement 1 is essentially designed depending on the available installation space and the required first contact pressure F 1 .

[0042] Fig. 2 shows the sealing arrangement 1, which is arranged in the axial direction A between a wheel bearing 2 and a body 18, whereby both the wheel bearing 2 and the body 18 are shown only in sections. The structure of the sealing arrangement 1 is similar to that shown in Fig. 1 shown embodiment, which is why only the differences are discussed below. Due to a different installation position of the sealing arrangement 1, which Fig. 1 is arranged mirror-inverted, the first axial distance I A1 is equal to or greater than 1.95 mm. This results in the following length and angle ratios for the embodiment shown here: I R 1 = I A 1 * 1 , 03 I R 2 = I A 1 / 1 , 59 d R 1 = I R 2 * 0 , 40 = I A 1 / 1 , 59 * 0 , 40 d R 2 = I R 2 * 0 , 45 = I A 1 / 1 , 59 * 0 , 45 α 1 = 33 ° bis 36 ° und α 2 = α 1 − 0 , 58 ° ± 1 ° β 1 = 36 ° bis 39 ° und β 2 = β 1 − 0 , 335 ° ± 1 °

[0043] The force ratio of the contact forces F 1 , F 2 and F 3 corresponds to that in relation to Fig. 1 described force ratio.

[0044] Fig. 3shows a further embodiment of the sealing arrangement 1 according to the invention. It can be seen that the carrier element 7 is designed slightly differently and the sealing arrangement 1 is shown alone, without reference to adjacent elements. In this embodiment too, the force ratio of the contact forces F 1 , F 2 and F 3 corresponds to that with respect to Fig. 1 described force ratio.

[0045] In the embodiment shown here, the first axial distance I A1 is equal to or greater than 2 mm. This results in the following length and angle ratios: I R 1 = I A 1 * 1 , 15 I R 2 = I A 1 / 1 , 45 d R 1 = I R 2 * 0 , 50 = I A 1 / 1 , 45 * 0 , 50 d R 2 = I R 2 * 0 , 50 = I A 1 / 1 , 45 * 0 , 50 α 1 = 25 ° bis 28 ° und α 2 = α 1 + 4 , 7 ° ± 1 ° β 1 = 30 ° bis 33 ° und β 2 = β 1 + 5 , 1 ° ± 1 °

[0046] In addition, the sealing arrangement 1 shown here further comprises a third axial sealing lip 19, which does not extend as far as the counter-rotating plate 14 and is arranged outside the second axial sealing lip 12 as viewed in the radial direction R. The third axial sealing lip 19 serves as a pre-seal 20 and forms a collecting labyrinth in the sealing chamber 17, which is intended to directly drain particles penetrating from the outside, such as dirt, dirty water, dust, etc., back to the outside. For this purpose, the third axial sealing lip 19 is arranged obliquely outwards at an angle γ with respect to the axis of rotation of the sealing arrangement 1, wherein the angle γ here is approximately 30°, for example. The pre-seal 20 is intended to protect the first and second axial sealing lips 11, 12 from the penetrating particles, thereby further increasing the service life of the sealing arrangement 1.

[0047] In addition, Fig.3an inner diameter DI of the counter-running plate 14 is specified, which in this case is 80 mm as an example. List of reference symbols

[0048] 1 Sealing arrangement 2 Wheel bearing 3 Wheel bearing flange 4 Rolling element 5 Cage 6 Bearing ring 7 Support element 8 Fastening section 9 Elastic sealing element 10 Elastic main body 11 First axial sealing lip 12 Second axial sealing lip 13 Radial sealing lip 14 Counter-running plate 15 Fastening section 16 Sealing element 17 Sealing chamber 18 Body 19 Third axial sealing lip 20 Pre-seal F, F 1 , F 2 , F 3 contact pressure I A1 axial distance I R1 , I R2 radial distance d R1 , d R2 radial thickness DI inner diameter α 1 , β 1 inner circumferential surface angle α 2 , β 2 outer circumferential surface angle γangle Rradial direction Aaxial direction

Claims

1. A sealing arrangement (1) for a wheel bearing (2), comprising: a carrier element (7) which can be connected to a first bearing part (6) of the wheel bearing (2); an elastic sealing element (9) having an elastic main body (10) arranged on the carrier element (7), wherein the elastic sealing element (9) further comprises at least a first axial sealing lip (11) and a second axial sealing lip (12) and at least one radial sealing lip (13) extending away from the main body (10), wherein an inner circumferential surface of the first axial sealing lip (11) is arranged at a first inner circumferential surface angle (α3) to the axis of rotation and an outer circumferential surface of the first axial sealing lip (11) is arranged at a first outer circumferential surface angle (α2) to the axis of rotation, wherein the first outer circumferential surface angle (α2) is defined as a function of the first inner circumferential surface angle (α1), and wherein an inner circumferential surface of the second axial sealing lip (12) is arranged at a second inner circumferential surface angle (β1) to the axis of rotation and an outer circumferential surface of the second axial sealing lip (12) is arranged at a second outer circumferential surface angle (β2) to the axis of rotation, wherein the second outer circumferential surface angle (β2) is defined as a function of the second inner circumferential surface angle (β1), and a counterplate (14) which can be connected to a second bearing part (6) and is arranged with one side facing the carrier element (7) such that the first axial sealing lip (11), the second axial sealing lip (12) and the radial sealing lip (13) are in grinding contact with the counterplate (14), wherein the first axial sealing lip (11) is designed such that it rests against the counterplate (14) with a first contact force (F1), the second axial sealing lip (12) is designed such that it rests against the counterplate (14) with a second contact force (F2), and the radial sealing lip (13) is designed such that it rests against the counterplate (14) with a third contact force (F3), wherein the contact forces (F1; F2; F3) are defined as a function of a predetermined force ratio, characterised in that the predetermined force ratio is defined by the following equations: first contact force F 1 = second contact force F 2 ± 0.9 N third contact force F 3 = 0.5 * first contact force F 1 ± 0.9 N2. The sealing arrangement (1) according to claim 1, wherein the first inner circumferential surface angle (α3) is in a range between 25° and 28°, the first outer circumferential surface angle (α2) is equivalent to α2=(α14.7°)±1°, and the second inner circumferential surface angle (β1) is in a range between 30° and 33° and the second outer circumferential surface angle (β2) is equivalent to β2=(β15.1°)±1°.

3. The sealing arrangement (1) according to claim 1 or 2, wherein the main body (10) of the elastic sealing element (9) is arranged at least in the region of the axial sealing lips (11, 12) in the axial direction (A) at a first axial distance (IA1) from the counterplate (14).

4. The sealing arrangement (1) according to claim 3, wherein the first axial sealing lip (11) and the second axial sealing lip (12) in the radial direction have a first radial distance (IR1) to each other on the counterplate (14) and a second radial distance (IR2) to each other on the carrier element (7), wherein the first radial distance (IR1) and the second radial distance (IR2) are defined as a function of the first axial distance (IA1).

5. The sealing arrangement (1) according to claim 4, wherein the first axial sealing lip (11) on the main body (10) in the radial direction (R) has a first radial thickness (dR1), and the second axial sealing lip (12) on the main body (10) in the radial direction (R) has a second radial thickness (dR2), wherein the first radial thickness (dR1) and the second radial thickness (dR2) are defined as a function of the second radial distance (IR2).

6. The sealing arrangement (1) according to one of claims 1 to 5, wherein the first axial sealing lip (11) and the second axial sealing lip (12) are arranged obliquely with respect to an axis of rotation of the wheel bearing (2), wherein a diameter of the axial sealing lips (11, 12) increases in the axial direction (A) when viewed from the main body (10) to the counterplate (14).

7. Use of a sealing arrangement (1) according to one of claims 1 to 6 for sealing a wheel bearing (2).

8. A wheel bearing unit for a motor vehicle, comprising: a wheel bearing (2) which is designed as a roller bearing, and a sealing arrangement (1) according to one of claims 1 to 6, which is arranged adjacent at least to one axial side of the wheel bearing (2).