Wheel bearing unit for supporting motor vehicle tyre of motor vehicle and method for mounting wheel bearing unit

Abstract

The invention relates to a wheel bearing unit for supporting a motor vehicle tyre of a motor vehicle, in particular a motor vehicle tyre of a truck, comprising: a rolling bearing () having at least one outer ring () and at least two inner rings (), between which rolling bodies () are guided; and a sealing unit () arranged in the radial direction between the outer ring (1) and at least one of the inner rings (1) for sealing the outer ring (1) against the inner rings (1), the mutually facing axial end faces of adjacent inner rings (1) bearing against each other, and the inner rings () are connected together in a form-fitting and force-fitting manner at their respective axial end faces facing each other.

Description

Technical Field

[0001] The present invention relates to a wheel bearing unit for supporting a motor vehicle tire of a motor vehicle. The present invention also relates to a method for installing the wheel bearing unit. Background Art

[0002] In the prior art, various wheel bearings, especially various wheel bearings for motor vehicles and commercial vehicles, are known. Wheel bearing units for commercial vehicles are usually designed as plug-in rolling bearing units with tapered roller bearings. For example, DE 10 2014 200 714 A1 discloses a rolling bearing unit in the form of a multi-row angular contact bearing, which can be used as a wheel bearing for a vehicle. This includes two rows of rolling elements, each of the two rows of rolling elements being guided between an inner ring and an outer ring. The outer ring is usually pressed into the wheel hub. The end faces of the inner rings facing each other form a small gap. This gap between the inner rings is called the preload in a plug-in tapered roller bearing in the un-tensioned state. Nowadays, the wheel bearing is tensioned and fixed by tightening an axle nut to a journal. The gap between the inner rings is compressed until the inner rings contact, thereby introducing a tension force into the wheel bearing. This tension force is crucial for the service life and frictional force of the wheel bearing. In the prior art, this preload is designed and defined by a technician. However, this is affected by many components and the tolerances of these components. Summary of the Invention

[0003] The object of the present invention is to be able to introduce a defined preload into the wheel bearing, which is as independent as possible of the tolerances of other wheel bearing components, in order to reduce the friction in the wheel bearing and increase the service life of the wheel bearing.

[0004] According to the present invention, this object is achieved by a wheel bearing unit according to the features of claim 1 and a method for installing a wheel bearing unit according to claim 8. The dependent claims provide advantageous further improvements of the present invention.

[0005] A wheel bearing unit for supporting a motor vehicle tire, especially a motor vehicle tire of a truck, according to the present invention includes a rolling bearing designed in at least two rows, the rolling bearing having at least two outer rings and at least two inner rings, wherein rolling elements are guided between the outer rings and the inner rings, and wherein the mutually facing axial end faces of adjacent inner rings abut against each other, wherein the axial end faces are aligned with each other, and wherein the inner rings are connected to each other in a form-fitting and force-fitting manner at their respective mutually facing axial end faces.

[0006] A sufficiently high connection force ensures that the inner ring forms a form - fit and force - fit connection. Thus, the preload and the associated tension force in the wheel bearing can be precisely defined and fixed. The tension force applied to the wheel bearing cannot be released from the wheel bearing.

[0007] Preferably, the rolling elements are tapered rollers. The wheel bearing unit according to the invention is particularly preferably used in commercial vehicles or trucks and is designed as a plug - in tapered roller bearing.

[0008] In an advantageous embodiment, a sealing unit is arranged radially between at least one outer ring and at least one inner ring in the outer ring for sealing the outer ring relative to the inner ring. The wheel bearing particularly preferably has two sealing units, wherein each sealing unit is arranged between the outer ring and the inner ring.

[0009] The sealing of the wheel bearing prevents the ingress of dust and water and thus significantly extends the service life of the bearing.

[0010] In another embodiment, the inner ring forms connecting portions on its respective facing axial end faces, and these connecting portions are locked to each other to form a form - fit. The connecting portions particularly refer to steps inserted into the end regions of the inner ring. Preferably, the connecting portions are hollow cylindrical and are concentrically arranged with each other when the inner ring is in the installed state. In the installed state, the connecting portions form a form - fit and force - fit connection.

[0011] The connecting portions, preferably two connecting portions, particularly preferably have a length of at least 20 mm to ensure sufficient stability.

[0012] In another exemplary embodiment of the invention, the rolling bearing is axially fixed by a retaining ring, such as a snap ring, particularly axially fixed on the journal. Since the rolling bearing is fully tensioned by the form - fit and force - fit connection of the inner ring, axial fixation by an axle nut is no longer required. Thus, the snap ring is sufficient for fixation and also offers advantages in terms of process simplification and weight reduction.

[0013] The invention also relates to a method for installing a wheel bearing, wherein two groups of rolling elements are inserted into the wheel hub, and the preload of the wheel bearing is set by a predefined target press - in distance of two inner rings, and the two inner rings are connected to each other in a form - fit and force - fit manner.

[0014] The target press - in distance is determined by X0 - Xvs, where X0 is the axial distance between the second end face of the inner ring and the end face of the outer ring, and Xvs is the predefined target preload that the wheel bearing should have.

[0015] During installation, the first row of rolling elements is first loaded with a slight preload and the distance X0 is determined. Then, the first row of rolling elements or the first group of rolling elements is axially pressed onto the wheel hub by means of the first outer ring. Then, the second row of rolling elements or the second group of rolling elements is axially pressed onto the wheel hub by means of the second outer ring. When the second row is pressed in, the outer end faces of the first inner ring and the second inner ring come into contact with each other, causing the first inner ring to move axially outwards. Then, the first inner ring is axially pressed in with a predefined pressing force, as a result of which the connecting parts on the inner rings lock with each other at the end faces and a force-locking and form-locking connection is formed. The target pressing distance X of the inner ring is defined as X0 - Xvs, and a predefined preload can thus be applied to the wheel bearing.

[0016] The method according to the invention enables a defined, very precise preload and thus a fixed friction to be set. Many dimensions and tolerances no longer have any influence on the preload of the bearing, which makes the production of the bearing more cost-effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features of the invention are apparent from the following description of the drawings, in which exemplary embodiments of the invention are shown, although the invention is not limited to these embodiments. In the drawings:

[0018] Figure 1 A half-section of a wheel bearing or a wheel bearing unit having a double-row rolling bearing is shown,

[0019] Figures 2a to 2d The installation steps of the wheel bearing are shown,

[0020] Figure 2e A detailed view of the inner ring during installation according to Figure 2c is shown,

[0021] Figure 2f A detailed view of the installed inner ring according to FIG. d is shown,

[0022] Figure 3 A sectional view of the inner ring in a not yet fully installed state is shown,

[0023] Figure 4 A section of the installed wheel bearing on the journal is shown. DETAILED DESCRIPTION

[0024] Figure 1A cross-sectional view of a wheel bearing or wheel bearing unit 1 with a rolling bearing 10 is shown. The wheel bearing or wheel bearing unit has two rolling body sets 11, 12. The rolling body sets 11, 12 include at least one outer ring 2a, 2b and one inner ring 3a, 3b, and rolling bodies 8 guided between the outer ring and the inner ring. The rolling bodies 8 are preferably designed as tapered rollers. The rolling body sets 11, 12 are pressed into the wheel hub 5. For this purpose, the wheel hub 5 has an axial stop, and the outer rings 2a, 2b are axially fixed to the axial stop. A sealing unit 4 is arranged between the inner rings 3a, 3b and the outer rings 2a, 2b. The sealing unit 4 prevents dust and water from entering the bearing. Outside the axial direction of the sealing unit 4, a sensor device (only partially) is shown. In particular, this includes a pole wheel attached to the wheel hub 5 and a sensor (not shown) for speed detection.

[0025] The inner rings 3a, 3b have connecting parts 3c or steps on their facing end faces 30a, 30b. These connecting parts are hollow cylindrical and can thus be locked to each other when in the installed state. In the installed state, the connecting parts 3c are arranged concentrically with each other.

[0026] When installing the wheel bearing unit, first press the rolling body set 11 axially against the stop, and load the rolling body set with a slight initial force. This is shown in Figure 2. Determine the distance X0. X0 is the axial distance between the second end face 30c of the inner ring 3a and the end face of the outer ring 2a. In the next method step (see Figure 2b ), press the two rolling body sets 11, 12 one by one into the wheel hub 5. This causes contact between the end faces 30a, 30b of the inner rings 3a, 3b, thereby axially pushing the inner ring 3a outward (see Figure 2c ). Then axially press the inner ring 3a in the direction of the inner ring 3b using a high press-fit force of at least 100 KN, for example, thereby generating a force fit and a form fit at the connecting parts 3c of the inner rings 3a, 3b ( Figure 2d ). The press-fit force must be high enough to prevent further pressing by tightening the axle nut. The target press-fit distance Xges is the determined value X0 minus the target preload Xvs. Using this installation method, the wheel hub 5 is tensioned with a defined preload Xvs and thus with a defined tension force. The preload can no longer be released from the system.

[0027] Figure 2e A detailed view of the inner rings 3a, 3b before the last installation step is shown, where the inner rings 3a, 3b are in contact with each other but not yet connected in a force fit and form fit manner ( Figure 2e ). Figure 2f The inner rings 3a, 3b after the installation has been completed are shown, where the inner rings 3a, 3b are connected in a force fit and form fit manner.

[0028] Figure 3 Shows a cross-sectional view of the inner rings 3a, 3b during installation. The connecting portion 3c of the two inner rings 3a, 3b overlaps axially partially, and is then further pushed together until the two inner rings form a force fit and a form fit. The length L of the connecting portion 3c is preferably at least 20 mm long.

[0029] Alternatively, the following method (not shown) can be used to install the wheel bearing unit 1. In a first step, a first rolling body group 11 having an inner ring 3a is axially pressed into the wheel hub 5. For this purpose, the wheel hub 5 has one, preferably two, axial stop portions in the form of steps. In the next step, the inner ring 3a is loaded with a slight initial force and the distance X0 is determined. Then the second rolling body group 12 is pressed into the wheel hub 5, causing the inner ring 3a having the rolling bodies 8 to slide axially out of the wheel bearing when the end faces 30a, 30b of the inner rings come into contact with each other. Then the inner ring 3a is pressed back into the bearing or the wheel hub 5 with a high press-fitting force such that a force fit and a form fit are formed on the inner rings 3a, 3b. The wheel hub 5 rotates during the press-fitting process. As described above, the target press-fitting distance Xges is determined by using X0 minus Xvs.

[0030] Figure 4 Shows a wheel bearing unit 1 with a mounted rolling bearing 10. It is no longer necessary here to tension the wheel bearing unit 1 by means of an axle nut as known in the prior art, since the unit 1 is already tensioned by the frictional connection between the inner rings 3a, 3b. Thus, the unit 1 is axially fixed to the journal 13 only by a retaining ring 9, such as a snap ring.

[0031] List of reference numerals

[0032] 1 Wheel bearing unit

[0033] 2a, 2b Outer ring

[0034] 2c End face of the outer ring

[0035] 3a, 3b Inner ring

[0036] 3c Connecting portion

[0037] 4 Sealing unit

[0038] 5 Wheel hub

[0039] 8 Rolling body

[0040] 9 Retaining ring

[0041] 10 Rolling bearing

[0042] 11, 12 Rolling body groups

[0043] 13 journal

[0044] End faces 30a, 30b

[0045] Second end face 30c

[0046] R Radial direction

[0047] A Axial direction

[0048] Xges Target press-in distance.

Claims

1. A wheel bearing unit (1) for supporting a motor vehicle tire, in particular a motor vehicle tire of a truck, the wheel bearing unit comprising a rolling bearing (10), the rolling bearing being designed in at least two rows, the rolling bearing having at least two outer rings (2a, 2b) and at least two inner rings (3a, 3b), wherein, rolling elements (8) are guided between the outer rings (2a, 2b) and the inner rings (3a, 3b), and wherein the mutually facing axial end faces (30a, 30b) of adjacent inner rings (3a, 3b) abut against each other, characterized in that the inner rings (3a, 3b) are connected to each other in a form - fit and force - fit manner at the respective mutually facing axial end faces (30a, 30b) of the inner rings.

2. The wheel bearing unit (1) according to claim 1, characterized in that, the rolling elements (8) are designed as tapered rollers.

3. The wheel bearing unit (1) according to claim 1 or 2, characterized in that, a sealing unit (4) is arranged in the radial direction R between at least one of the outer rings (2a, 2b) and at least one of the inner rings (3a, 3b), the sealing unit being used to seal the outer ring (2a, 2b) relative to the inner ring (3a, 3b).

4. The wheel bearing unit (1) according to one of the preceding claims, characterized in that, the inner rings (3a, 3b) have connecting portions (3c) on the respective facing axial end faces (30a, 30b) of the inner rings, the connecting portions being locked to each other to form a form - fit.

5. The wheel bearing unit (1) according to claim 4, characterized in that, the connecting portions (3c) have a length (L) of at least 20 mm.

6. The wheel bearing unit (1) according to claim 4 or 5, characterized in that, the connecting portions (3c) are hollow cylindrical and are arranged concentrically with each other.

7. The wheel bearing unit (1) according to one of the preceding claims, characterized in that, the rolling bearing (10) is axially fixed by a retaining ring (9).

8. A method for installing a wheel bearing unit (1) according to one of claims 1 to 7, wherein, two groups of rolling elements (11, 12) are inserted into a wheel hub (5), and the pre - load of the wheel bearing is set by a predefined target press - in distance (Xges) of two inner rings (3a, 3b), the inner rings being connected to each other in a form - fit and force - fit manner.

9. The method according to claim 8, characterized in that, the target press - in distance (Xges) is determined by X0 - Xvs, where X0 is the axial distance between the second end face of the inner ring and the end face of the outer ring, and Xvs is a predefined target pre - load.

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