WHEEL BEARING UNIT FOR A MOTOR VEHICLE AND MOTOR VEHICLE

Abstract

A wheel bearing unit for a motor vehicle, comprising a wheel hub, a wheel bearing housing and a rolling bearing by which the wheel hub is mounted rotatably in relation to the wheel bearing housing. The rolling bearing has at least one row of rolling elements which are guided on the wheel hub side in a bearing inner ring which is designed as a separate component in relation to the wheel hub and which is fixedly connected to the wheel hub. The wheel hub has a through opening with an inner toothing, via which through opening the wheel hub can be connected in a non-rotational manner to a drive journal which is provided with an external toothing.

Claims

1. A wheel bearing unit for a motor vehicle, comprising a wheel hub, a wheel bearing housing and a rolling bearing by means of which the wheel hub is mounted rotatably in relation to the wheel bearing housing, wherein the rolling bearing has at least one row of rolling elements which are guided on the wheel hub side in a bearing inner ring which is designed as a separate component in relation to the wheel hub and which is fixedly connected to the wheel hub, wherein the wheel hub has a through opening with an inner toothing, via which through opening the wheel hub can be connected in a non-rotational manner to a drive journal which is provided with an external toothing, wherein the inner toothing is formed comprising a first toothing portion, a second toothing portion and a toothless portion which, viewed in the axial direction, lies between the two toothing portions and separates the two toothing portions from one another, wherein the toothless portion of the inner toothing, viewed in the axial direction, is arranged in such a way that the toothless portion is positioned radially opposite the end face of the bearing inner ring on the bearing inner side.

2. A wheel bearing unit according to claim 1, wherein relative to a root diameter of the toothing portions of the inner toothing, the toothless portion of the inner toothing has a diameter for which applies: $1\frac{\mathrm{diameter}\left(D_{\mathrm{Ab}}\right)\mathrm{of}\mathrm{the}\mathrm{toothless}\mathrm{portion}}{\mathrm{root}\mathrm{diameter}\left(D_F\right).}1,2$

3. The wheel bearing unit according to claim 1, wherein the through opening of the wheel hub comprises a support region having the inner toothing, a fastening region having a bearing shoulder, and an intermediate region arranged between the support and fastening regionsas viewed in the axial directionand in that, relative to the root diameter, the intermediate region has an intermediate region diameter for which applies: $\frac{\mathrm{intermediate}\mathrm{region}\mathrm{diameter}\left(D_Z\right)}{\mathrm{root}\mathrm{diameter}\left(D_F\right).}>1$

4. The wheel bearing unit according to claim 2, wherein the intermediate region diameter is greater than or equal to the diameter of the toothless portion of the inner toothing.

5. The wheel bearing unit according to claim 2, wherein relative to the root diameter, the fastening region has a fastening region diameter for which applies: $\frac{\mathrm{fastening}\mathrm{region}\mathrm{diameter}\left(D_B\right)}{\mathrm{root}\mathrm{diameter}\left(D_F\right).}1,2$

6. The wheel bearing unit according to claim 1, wherein viewed in the axial direction, the inner toothing has a length, and in that, relative to the length of the inner toothing, the toothless portion has an axial portion length for which applies: $0.1\frac{\mathrm{portion}\mathrm{length}\left(L_{\mathrm{Ab}}\right)}{\mathrm{length}\mathrm{of}\mathrm{inner}\mathrm{toothing}\left(L_{\mathrm{In}}\right).}0.3$

7. The wheel bearing unit according to claim 3, wherein viewed in the axial direction, the inner toothing has a length, and in that relative to the length of the inner toothing, the intermediate region has an axial intermediate region length for which applies: $0.5\frac{\mathrm{intermediate}\mathrm{region}\mathrm{length}\left(L_Z\right)}{\mathrm{length}\mathrm{of}\mathrm{inner}\mathrm{toothing}\left(L_{\mathrm{In}}\right).}0.7$

8. The wheel bearing unit according to claim 3, wherein viewed in the axial direction, the inner toothing has a length, and in that, relative to the length of the inner toothing, the fastening region has an axial fastening region length for which applies: $0.3\frac{\mathrm{intermediate}\mathrm{region}\mathrm{length}\left(L_B\right)}{\mathrm{length}\mathrm{of}\mathrm{inner}\mathrm{toothing}\left(L_{\mathrm{In}}\right).}0.6$

9. The wheel bearing unit according to claim 2 characterized in that the toothless portion of the inner toothing is formed like an undercut.

10. A motor vehicle, comprising a wheel bearing unit, the wheel bearing unit is formed according to claim 1.

11. The wheel bearing unit according to claim 2, wherein the through opening of the wheel hub comprises a support region having the inner toothing, a fastening region having a bearing shoulder, and an intermediate region arranged between the support and fastening regionsas viewed in the axial directionand in that, relative to the root diameter, the intermediate region has an intermediate region diameter for which applies: $\frac{\mathrm{intermediate}\mathrm{region}\mathrm{diameter}\left(D_Z\right)}{\mathrm{root}\mathrm{diameter}\left(D_F\right).}>1$

12. The wheel bearing unit according to claim 3, wherein the intermediate region diameter (D.sub.Z) is greater than or equal to the diameter of the toothless portion of the inner toothing.

13. The wheel bearing unit according to claim 3, wherein relative to the root diameter, the fastening region has a fastening region diameter for which applies: $\frac{\mathrm{fastening}\mathrm{region}\mathrm{diameter}\left(D_B\right)}{\mathrm{root}\mathrm{diameter}\left(D_F\right).}1,2$

Description

BRIEF DESCRIPTION OF THE FIGURES

[0021] Further advantages and possible applications of the invention result from the following description in conjunction with the exemplary embodiment shown in the drawing.

[0022] In the drawing:

[0023] FIG. 1 shows a side view of a wheel bearing unit of a motor vehicle according to the prior art;

[0024] FIG. 2 shows a side view of a wheel bearing unit according to the invention; and

[0025] FIG. 3 shows an enlarged portion of FIG. 2.

DETAILED DESCRIPTION

[0026] FIG. 1 shows a wheel bearing unit for a motor vehicle, indicated in its totality by the reference numeral 10. The wheel bearing unit 10 comprises a wheel hub 12, a wheel bearing housing 14 and a rolling bearing 16, via which the wheel hub 12 is rotatably mounted relative to the wheel bearing housing 14.

[0027] As can be further seen from FIG. 1, the rolling bearing 16 has two rows of rolling elements 18. While the left row of rolling elements 18in FIG. 1rolls in a bearing race formed in the wheel hub 12, the right row of rolling elements 18 is guided in a bearing inner ring 20 having a corresponding bearing race and which is firmly connected to the wheel hub 12.

[0028] The wheel hub 12 also has a through opening 22, which is provided in some regions with an inner toothing 24. Via the inner toothing 24, the wheel hub 12 can be non-rotatably connected in a known manner to a drive journal of a joint sourcenot shown here for reasons of claritywhich has external toothing corresponding to the inner toothing 24. In the following, the reference sign D.sub.Z denotes the root diameter of the inner toothing 24.

[0029] A disadvantage of the prior art is that as a result of the local material taper of the wheel hub 12 caused by the bearing inner ring 20, in particular in the region of the transition to the end face 20-1 of the bearing inner ring 20 on the bearing inner side, high notch stresses occur in the tooth base of the inner toothing 24, which in turn can lead to toothing cracks in the inner toothing 24 and thus cause premature failure of the wheel hub 12 or the wheel bearing unit 10. This is where the invention comes in:

[0030] As FIG. 2 and FIG. 3 show, it is now provided that the inner toothing 24 has a first toothing portion 24-1, a second toothing portion 24-2 and a toothless portion 24-3, which, viewed in the axial direction a, lies between the two toothing portions 24-1, 24-2 and separates the two toothing portions 24-1, 24-2 from one other.

[0031] As can be further seen from FIG. 2 and in particular FIG. 3, the portions 24-1, 24-2, 24-3 forming the inner toothing 24 are arranged and dimensioned in such a way that, viewed in the axial direction a, the toothless portion 24-3 is positioned radially opposite the end face 20-1 of the bearing inner ring 20 on the bearing inner side.

[0032] Since the inner toothing 24 is now designed to be toothless in the critical portion of the wheel hub 12, i.e. in the region of the transition to the end face 20-1 of the bearing inner ring 20 on bearing inner side, it is ensured in an advantageous manner that the local notch stresses leading to toothing cracks are reduced, which has a positive effect on the service life of the wheel hub 12 and thus of the wheel bearing unit 10.

[0033] The toothless portion 24-3 is formed in the present case in the form of an undercut or turned region introduced into the through opening 22, and has a diameter D.sub.Ab which in the present case is 10% larger than the root diameter D F of the inner toothing 24.

[0034] Viewed in the axial direction a, the toothless portion 24-3 is dimensioned such that it has an axial length L.sub.Ab corresponding to 10% to 30% of the total length L.sub.ln of the inner toothing 24, see FIG. 2 and FIG. 3.

[0035] As can be further seen from FIG. 2, the through opening 22 of the wheel hub 12 has, in addition to the region forming the inner toothing 24, hereinafter also referred to as the support region 22-1, a fastening region 22-2, as well as an intermediate region 22-3 arranged between the support region 22-1 and the fastening region 22-2as viewed in the axial direction a-.

[0036] The reference sign L.sub.B denotes the axial length of the fastening region 22-2, and the reference sign L.sub.Z denotes the axial length of the intermediate region 22-3. Accordingly, the diameter of the fastening region 22-2 is denoted by D B and the diameter of the intermediate region 22-3 by D.sub.Z, see FIG. 2.

[0037] In order to minimize the wear of the broaching tool during the manufacture of the inner toothing 24, the diameter of the intermediate region D.sub.Z is larger than the root diameter D.sub.F of the inner toothing 24. In addition to the lower wear, the increase in diameter also advantageously results in a weight saving. In the present case, the diameter D.sub.Z is selected so that it corresponds to the diameter D.sub.Ab of the toothless portion 24-3, i.e.

D.sub.Z=D.sub.Ab=1.1*D.sup.F

[0038] Thus, the regions 24-3 and 24-2 can advantageously be manufactured in one working step. The fastening region 22-2 is dimensioned in such a way that the fastening diameter D.sub.B is larger than the root diameter D.sub.F by a factor of 1.2. This ensures that a sufficiently large fastening shoulder 26 is available for the fastening means, such as a nut or bolt, via which the wheel hub 12 is connected to the drive journal of a joint source, see FIG. 2.

[0039] To ensure a compact design of the wheel bearing unit 10, the axial lengths L.sub.B and L.sub.Z of regions 22-2 and 22-3 are presently dimensioned such that the axial length L.sub.B of the fastening region 22-2 corresponds to about 30% to 60% of the total length L.sub.ln of the inner toothing 24 and the axial length L.sub.Z of the intermediate region 22-3 corresponds to about 50% to 70% of the total length L.sub.ln of the inner toothing 24.