AU759754B2

AU759754B2 - Wheel suspension, especially for nonpowered vehicle axles

Info

Publication number: AU759754B2
Application number: AU75206/00A
Authority: AU
Inventors: Michael Mathieu
Original assignee: BPW Bergische Achsen KG
Current assignee: BPW Bergische Achsen KG
Priority date: 1999-09-21
Filing date: 2000-09-19
Publication date: 2003-05-01
Anticipated expiration: 2020-09-19
Also published as: ES2199861T3; WO2001021418A1; HUP0104229A2; DE50002438D1; PL200630B1; CN1322170A; TR200101390T1; JP2003509280A; EP1131214A1; JP4539949B2; HU223227B1; CN1265977C; DE19945255A1; HUP0104229A3; BR0007161A; PL347638A1; EP1131214B1; AU7520600A; BR0007161B1

Description

The invention concerns a wheel mounting, in particular for non-driven vehicle axles, with a wheel hub rotatably mounted on an axle stub by meansof antifriction bearings, which is retained by an axle nut screwed with its inside thread onto an outside thread of the axle stub.

From EP 0 529 252 B1 a wheel mounting for trailer axles is known, the central axle nut of which has in the vicinity of its outside a plurality of radially extending slots. The pitch of the slots is asymmetrical and in a clockwise direction it is twice 600, once 450, again twice 600 and once 750 By virtue of this a maximum'angle of rotation of the axle nut of 150 is achieved on the axle stub for the insertion of a locking pin. With these values a good and, in most cases, an adequate axial bearing adjustment is achieved.

i The tightening force, with which the axle nut is tightened after placing the hub unit on the axle stub, is of equal, if not greater importance for the optimum bearing adjustment. For this purpose most vehicle manufacturers specify the tightening torques required for this operation. However, the achieving of the correct tightening torque presupposes the correct handling of the tool used during the tightening.

The provision of a wear layer on that face of an axle nut, secured by an additional locknut, which faces inwards towards the wheel bearing is known from DE 37 13 224 Al, against which layer the axle nut rests on the inner ring of the antifriction -,bearing when pre-tensioned with a specified torque. The wear layer is made of a material that is strong enough to endurethe axial pressure when the axle nut is pre-tensioned, but it disappears after starting up the motor vehicle due to the temperature increase caused by the operation. Accordingly, a certain, desired bearing play occurs only during driving. To prevent a subsequent unintentional loosening of the axle nut, it is secured by means of the outside situated locknut.

1A The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia before the priority date of each claim of the application.

It would be desirable to exclude sources of errors for a wheel mounting, in particular for non-driven vehicle axles, such as may occur due to incorrect tightening of the central axle nut.

"..00 oo **eoo o .doc 2 To achieve this objective for a wheel mounting of the type mentioned in the introduction it is proposed that the axle nut is made up from an inner part that has an inside thread and an outer part that is coaxial with the latter, on the outer part flats to apply the spanner are formed necessary for the tightening and loosening of the axle nut, that the outer part is displaceable on the inner part and is connected with the inner part by means of one or a plurality of spring-biased locking elements in such a manner that in the direction of loosening a considerably higher torque can be transferred on to the inner part than in the direction of tightening.

Preferably in this case the outer part has an axial denticulation that biased by a spring engages a corresponding counter-denticulation of the inner part, while the denticulation has flanks which in the case of the outer part are sloping in the direction of tightening and are steep in the direction of loosening.

In the case of a wheel mounting of this type of construction sources of error caused by incorrect tightening of the axle nut are out of the question. For a controlled tightening of the axle nut it is not necessary, for example, to use a torque wrench, the setting of which to the correct torque value in practice often represents a source of error. In the case of the axle nut used according to the invention the maximum achievable tightening torque is set, as it were, already in the axle nut, whereby this is made up from an inner part that is screwed on to the axle stub, and an outer part on which the flats necessary to apply the spanner for the tightening of the axle nut are formed. The inner part and the outer part engage one another as a sort of a denticulation, wherein the denticulation has flanks that in the case of the outer part are sloping in the direction of tightening and steep in the direction of loosening. Furthermore, the engagement of the denticulation with the counter-denticulation is spring-biased, while not only the slope of the flanks, but also the strength of the spring bias are firmly set and in this manner limit the maximum moment transferable from the outer part to the inner part. Accordingly, erroneous operation by applying a too high a tightening torque are not possible. A too high a tightening torque results in increased loads on the antifriction bearings and, consequently, in premature wear of the bearings.

A development proposes to form the denticulation on one face of the outer part, and that a compression spring to achieve the spring bias to be supported on the other face, averted from the first face, of the outer part. In this case, to absorb the reaction forces, the compression spring is preferably supported by a radially protruding shoulder, that is integrally formed with the inner part.

To enable the retrofitting of the axle nut on existing wheel mountings, its overall dimensions should be possibly small. Since the overall dimensions are also determined by the size of the compression spring used, a further development proposes to use a single or multiple disc spring as compression spring. With such a disc spring a high spring force can be achieved with small dimensions and, in addition, with the dimensions adapted to suit the basic shape of the axle nut. For this purpose it is a further advantage if the disc spring rests with its large diameter on the outer part and with its small diameter on the inner part.

A further development of the wheel mounting proposes that the inner part of the axle nut is made up from a sleeve-shaped section as well as a flange-shaped section, and that the flange-shaped section is made up from an inner flange section on which the counter-denticulation is formed and an outer flange section, with which the axle nut engages from behind an undercut of the wheel hub. Such a functional division between the inner flange section on the one hand and the outer flange section on the other makes it feasible to install and then dismantle the hub with the mounted antifriction bearings, a thrust ring and the axle nut being pre-assembled as a unit. With its outer flange section the axle nut forms a removing tool, whereby the outer flange section of its inner part engages behind the undercut of the wheel hub. This undercut of the wheel hub is preferably formed by a circlip inserted into the external opening of the wheel hub.

In contrast to this the inner flange section of the inner part has a different purpose. The counter-denticulation is formed on its inner flange part. In addition, it rests against an inner ring of the outside antifriction bearing of the wheel mounting that sits on the axle stub and in this manner secures the outside antifriction bearing and the entire wheel mounting.

A preferred development of the wheel mounting is characterised by a locking element to lock the rotation of the inner part of the axle nut on the axle stub.

In the case of a further development of the wheel mounting the locking elements are spring-biased pins or ball bearings that can be snapped into a denticulation, preferably under the pressure of a disc spring.

Further details and advantages will become apparent from the following description of the associated drawings, wherein a preferred embodiment of a wheel mounting constructed according to the invention is illustrated. The drawings show in: Fig. 1 a wheel mounting, longitudinally sectioned; Fig.2 details of the wheel mounting according to Fig.1 in the region of the outer antifriction bearing and the central axle nut; Fig.3 a top view on the axle nut mounted on the axle stub; Fig.4 a section across the inner part of the axle nut; a perspective view of the outer part of the axle nut; Fig.6 a top view on the inner part corresponding to arrow VI shown in Fig.4; Fig.7 a partial section of an embodiment of the central axle nut modified from that of Figs.l-6 with a plurality of spring-loaded locking elements.

At the end of an axle body 1 an axle stump 2 is fastened or formed onto it, that has two bearing seats 3, 4 at a distance from one another for an inner antifriction bearing 5 and an outer antifriction bearing 6. On the two antifriction bearings 5, 6 an integrally constructed wheel hub 7 is freely rotatably mounted. On one side of the wheel hub 7 a brake drum or brake disc and on the other side a wheel using wheel studs can be fastened.

On the outside of the inner antifriction bearing 5 a thrust ring 8 is provided that on its outside periphery has a shoulder 8a extending up to the inside wall of the wheel hub 7. In front of the shoulder 8a of the thrust ring 8 first circlip 9 is inserted into the continuous groove of the wheel hub.

At the other end, covered by a cap, in front of the outer antifriction bearing 6 an axle nut 10 is provided with a flange-shaped section 11 formed on it, the outside edge of which extends up to the vicinity of the inside wall of the wheel hub 7.

Outside of the outside edge of the flange-shaped section 11 a second circlip 12 is inserted into a continuous groove of the wheel hub 7. The inside diameter of this circlip is smaller than the largest diameter of the flange-shaped section 11. By interposing an annular disc 13 the flange-shaped section 11 of the axle nut rests on the inner ring 14 of the outer antifriction bearing 6.

By means of an inside thread the axle nut 10 is screwed on to an outside thread of the free end of the axle stub 2. The inside thread of the axle nut 10 is situated on an inner part 16 of the axle nut. Another component of the axle nut is an outer part 17, on which the flats 18 necessary to apply the spanner for tightening and loosening the axle nut are formed.

The inner part 16 of the axle nut is made up from a sleeve-shaped section 19 as well as a flange-shaped section 11. On the inside periphery of the sleeve-shaped section 19 the inside thread is provided. The flange-shaped section 11 of the inner part 16 consists of an inner flange section 21 and an outside flange section 22. The inner flange section has on one of its side a support surface for the annular disc 13 and on its other side, that is facing the outer part 17, it has denticulation. The outer flange section 22 engages from behind in the above described manner the undercut of the wheel hub 7 that is defined by the circlip 12.

Components of the axle nut 10 are also a disc spring 23 as well as a securing element 25 provided with a clip 25, this securing element preventing a subsequent rotation between the axle nut 10 and the axle stub 2.

It can be seen from Figs.2-6, that the outer part 17 of the axle nut 10 is provided with a denticulation 26, and the inner part 16 of the axle nut with a corresponding counter-denticulation 27. The denticulation 26 and the counter-denticulation 27 are axially aligned, consequently engage one another in the radial plane. The structure of the denticulation can be best seen from Fig.5 on the example of the denticulation 26 of the outer part 17. The denticulation has flanks 28a, 28b, that have sloping shapes in the direction 29 of tightening and are steep in the direction of loosening. The counter-denticulation 27 of the inner part 16 can have a corresponding structure.

The disc spring 23 rests with its inside edge on a radially protruding shoulder of the inner part 16, whereas the outside edge rests against that end face 31 of the outer part 17 which is averted from the denticulation 26 and, accordingly, faces outward. Instead of the simple disc spring 23 a packet of disc springs may be provided. The disc spring 23 exerts a pressure on the outer part 17 in the direction of the inside flange section of the inner part 16, resulting in the engagement, under pressure, of the denticulation and counter-denticulation. In this manner the axle nut 10 acts like a ratchet. If a specified torque is exceeded in the direction of tightening, the sloping flanks 28a of the denticulation 26 can climb on the corresponding flanks of the counter-denticulation 27, consequently the outer part 17 will overrun the inner part 16 that is held rigidly during the tightening. Consequently, a tightening of the axle nut 10 with a too high a torque is not possible. The maximum tightening torque is determined by the spring characteristics of the disc spring 23 as well as the geometry and, in particular, the slope of the flank of the denticulation 26 and of the counter-denticulation 27. In the direction of loosening, however, the torque is always fully transmitted due to the steep flanks 28b.

After tightening the axle nut 10 it has to be secured against unintentional loosening. For this purpose the cylindrical end spigot 32 of the axle stub 2 has an axially extending groove 33, like the one known, for example, as a feather key groove. The securing element 25 can be inserted into the groove 33 from the outside. The securing element has on its outside an axially extending denticulation structure 34 that engages the internal denticulation 35 of the inner part 16 having the same pitch. The internal denticulation 35 is a straight denticulation extending over 3600 that is limited to the outer part of the sleeveshaped section 19 of the inner part 16, for which purpose the inner part 16 has a correspondingly turned recess, on the circumference of which the teeth of the internal denticulation 35 are distributed.

Fig.3 shows that the block-like securing element 25 is narrower in the circumferential direction than the width of the groove 33. In Fig.3 a circumferential play a is shown on one side and a circumferential play b on the other side of the securing element 25. The sum of the circumferential plays a and b equals the pitch t common for the denticulation structure 34 of the securing element 25 and the internal denticulation 35 of the axle nut. In this manner it will be ensured that after tightening the axle nut, independently from the position of the particular position of the teeth, the securing element 25 can be pushed on every occasion into the groove 33 and be secured by means of the clip 24 wrapped around the end spigot 32. Therefore the circumferential play of the axle nut is limited to the very small angular range of a single pitch t. Depending from the pitch of the thread on the axle nut and axle stub, in the case of such a small rotational angles such axial adjustments of the axle nut 10 are achieved which are only fractions of a millimetre and therefore approach an optimum adjustment of the wheel mounting.

In the case of the embodiment of the axle nut 10 shown in Fig.7, components of the outer part 17 are several pins 36, ball bearings or similar locking elements, that are biased by a spring. This spring bias can be produced, for example, by a disc spring 23 pressing in this case simultaneously all pins 36. Each pin 36 is axially guided in its own guide 37 in the material of the outer part 17. At that end which is averted from the spring 23, each pin 36 has as denticulation 26 at least one tooth. This denticulation assumes here a function of the multiple denticulation 26 of the outer part 17 according to Figs.l-6, i.e. the engagement of the counterdenticulation 27 of the inner part 16. In the case of the embodiment according to Fig.7 the torque is transferred also in the direction 38 of tightening from the outer part 17 on to the inner part 16, whereas the pins 36 lock in the direction of loosening.

List of reference numerals 1 Axle body 2 Axle stub 3 Bearing seat 4 Bearing seat Inner antifriction bearing 6 Outer antifriction bearing 7 Wheel hub 8 Thrust ring 8a Shoulder 9 Circlip Axle nut 11 Flange-shaped section 12 Circlip 13 Annular disc 14 Inner ring of bearing Outside thread of the axle stub 16 Inner part 17 Outer part 18 Flat to apply spanner 19 Sleeve-shaped section Bearing surface 21 Inner flange section 22 Outer flange section 23 Disc spring 24 Clip Securing element 26 Denticulation 27 Counter-denticulation 28a Sloping flank 28b Steep flank 29 Direction of tightening Shoulder 31 End face 32 End spigot 33 Groove 34 Denticulation structure Internal denticulation, straight denticulation 36 Pin 37 Guide 38 Direction of tightening a Play b Play t Pitch

Claims

1. A wheel mounting, in particular for non-driven vehicle axles, with a wheel hub rotatably mounted on an axle stub by means of antifriction bearings, which is retained by an axle nut screwed with its inside thread onto an outside thread of the axle stub, wherein the axle nut is made up from an inner part that has an inside thread and an outside thread and an outer part that is coaxial with the latter, on the part flats to apply the spanner are formed necessary for the tightening and loosening of the axle nut, that the outer part is displaceable on the inner part and is connected with the inner part by means of one or a plurality of spring-biased locking elements in such a manner that in the direction of loosening a considerably higher torque can be transferred on to the inner part than in the direction of tightening, oo00

2. A wheel mounting according to claim 1, wherein the outer part with an axial denticulation biased by a spring engages a corresponding counter- !°'°"denticulation of the inner part, and that the denticulation has flanks which in the case of the outer part are sloping in the direction of tightening and are steep in the direction of loosening. i

3. A wheel mounting according to claim 2, wherein the denticulation is formed on one face of the outer part, and that a compression spring to achieve the S.i :spring bias is supported on the other face averted from the first face, of the outer part.

4. A wheel mounting according to claim 1 or claim 2, wherein to absorb the reaction forces the compression spring is supported by a radially protruding shoulder of the inner part.

A wheel mounting according to claim 3 or claim 4, including a single or multiple disc spring as the compression spring.

6. A wheel mounting according to claim 5, wherein the disc spring rests with its large diameter on the outer part and with its small diameter on the inner part.

7. A wheel mounting according to any one of the preceding claims, wherein the inner part is made up from a sleeve-shaped section as well as a flange- shaped section, and that the flange-shaped section is made up from an inner flange section, on which the counter-denticulation is formed and an outer flange section with which the axle nut engages from behind an undercut of the wheel hub.

8. A wheel mounting according to claim 7, wherein the undercut of the wheel hub is formed by a circlip inserted into the external opening of the wheel hub.

9. A wheel mounting according to claim 7 or claim 8, wherein with its inner i flange section the inner part rests axially against an inner ring of the outer antifriction bearing of the wheel mounting that sits on the axle stub.

A wheel mounting according to any one of the preceding claims, wherein ~one of the two parts axle stub or inner part has an axially extending groove, in which a securing element is situated, and that a section of the securing element protruding from the groove has a profiled section, preferably a denticulation structure, that in a form-locking manner engages a profiled S° section extending over 3600, with a preferably straight denticulation with axially extending teeth, the other two parts, namely the inner part and the S. axle stub. °0

11. A wheel mounting according to claim 10, wherein the circumferential play of the securing element in the groove is equal to or greater than the pitch of the straight denticulation.

12. A wheel mounting according to claim 1 or 2, wherein the locking elements are spring-biased pins or ball bearings that can be snapped into the denticulation, preferably under the pressure of a disc spring.

75206-00.doc 11

13. A wheel mounting according to any one of the embodiments substantially as herein described and illustrated. DATED: 24 December, 2002 PHILLIPS ORMONDE FITZPATRICK Attorneys for: BPW BERGISCHE ACHSEN KOMMANDITGESSELSCHAFT *.t *o* *o o *oe *eo