Hub unit with connection by means of cup spring

Abstract: A hub unit comprises a wheel bearing (1) and a driving axle (10) stub which is situated in a correspondingly shaped, concentric opening in the rotatable ring of the wheel bearing, and in the direction of rotation interacts by means of unround shapes (11,12) with said ring, which driving axle stub has an axle end projecting from the opening in said ring. The axle end interacts with the inner periphery of a cup spring (16) whose outer periphery is supported under pre-tension on said ring. The cup spring (16) is accommodated in a peripheral groove provided in the axle end.

Description: The invention relates to a hub unit comprising a wheel bearing and a driving axle stub which is situated in a correspondingly shaped, concentric opening in one of the rings of the wheel bearing and in the direction of rotation interacts by means of unround shapes with said ring, which driving axle stub has an axle end projecting from the opening in said ring. Such a hub unit is known from FR-A-2 511 950: the driving axle stub and the rotatable ring thereof can be provided with meshing keyways and grooves for transmitting the driving couple to the rotatable ring and the wheel fixed thereto. The hub unit is held together by means of a screw thread provided on the axle end and a nut supported on the rotatable ring and interacting with said screw thread. In the case of this known hub unit the required pre-tension is applied by tightening the screw connection with a predetermined tightening couple. This has the disadvantage that the required pre-tension is not always applied correctly, in view of the uncertainty concerning the amount of friction in the screw connection. Besides, it is not easy to ascertain afterwards whether there has been improper removal and fitting. The object of the invention is therefore to provide a hub unit which does not have these disadvantages. That object is achieved through the fact that the axle end interacts with the inner periphery of a cup spring whose outer periphery is supported under pre-tension on said ring. The fixing of the driving axle stub by means of a cup spring can be carried out using a special tool. This has the advantage of quick and relatively simple fitting. In addition, it makes improper fitting and removal difficult. Removal of the cup spring is not easy without a special tool. Removal of the cup spring involves such deformation thereof that re-use is out of the question. The advantage of this is that when the hub unit is being assembled again a new cup spring must be used, which improves the quality and reliability of the connection. The cup spring can be accommodated in a peripheral groove provided in the axle end. In that way a simple, cheap construction is obtained. Moreover, the position of the groove can be determined accurately relative to the ring of the bearing in question, in such a way that the pretension in the fitted cup spring can lie within narrow limits. Moreover, the cup spring can be supported on an essentially radially running face of said ring. In order to make the fitting easier, the cup spring can have a radial cut. The driving axle stub is preferably accommodated in an opening formed in the inner ring, and the cup spring is supported on a face of said inner ring which is staggered inwards. Such a design is compact and low in weight. The driving axle stub can also be provided with a shoulder at a distance from the axle end, which shoulder is supported on the side of the rotatable ring facing away from the cup spring. The distance between said shoulder and the groove in the axle end, together with the thickness of the inner ring, has an influence on the pre-tension obtained in the cup spring. In a preferred embodiment the driving axle stub is part of a constant-velocity joint. At least one of the edges of the of the cup spring, which are facing away from each other in the axial direction, is bevelled. Preferably, both said edges are bevelled. Thereby, assembling of the hub unit is simplified, in particular in cases where the cup spring is highly preloaded. Under these circumstances, the relatively sharp edges of the cup spring might easily damage the material of the ring, leading to indentations which would prevent the cup spring from sliding into place. Such embodiment of the cup spring is particularly fruitful in a process for assembling a hub unit, comprising the steps of sliding the rotatable ring of a wheel bearing over a driving axle stub until the axle end projects from the opening in said ring, sliding a cup spring over said axle end until its outer periphery abuts said ring, preloading said ring by further sliding its internal periphery over said axle end, until said internal periphery snaps behind an abutment on the axle end, which abutment faces the ring. The invention will now be explained in greater detail with reference to two exemplary embodiments shown in the figures. Figure 1 shows a first exemplary embodiment of the hub unit according to the invention. Figure 2 shows a second exemplary embodiment. Figure 3 shows a top view of the cup spring according to Figure 2. The hub unit shown in Figure 1 comprises a wheel bearing indicated in its entirety by 1, which bearing comprises an outer ring 2 and an inner ring 3. Two rows of balls 4 are provided between outer ring 2 and inner ring 3. The bearing space in which said balls are situated is sealed off by means of seals 5, 6. The outer ring 2 has threaded holes 7 for fixing to a wheel suspension construction. Inner ring 3 has threaded holes 8 to which a wheel can be fixed. The inner ring 3 has a concentric opening 9, into which the axle stub, indicated in its entirety by 10, is inserted. Said axle stub has on its outer periphery keyways and key grooves 11, which project into correspondingly shaped keyways and key grooves 12 in the concentric opening 9. By means of said keyways and key grooves 11, 12 the axle stub 10 can exert a driving couple on the inner ring 3 and on the wheel fixed thereto. The axle end 13 of the axle stub 10 projects from the opening 9, past the radial face 14 of the inner ring 3. A peripheral groove 15, in which cup spring 16 is accommodated, is provided in the periphery of the axle end 13. Said cup spring rests with its outer periphery on the radial face 14, in particular on the recessed part 17 thereof. At a distance from axle end 13, the axle stub 10 has a shoulder 18 which is supported against the inner ring 3. The axial distance between the radial faces 19 and 14 and the recessed part 17, and also the distance between the peripheral groove 13 and the shoulder 18, is selected in such a way that the cup spring 16 rests under pretension against the radial face 14 or the recess 17 when the shoulder 18 and the radial face are resting against each other. This means that a stipulated, constant pretension can remain ensured in the connection between axle stub 10 and inner ring 3. In the exemplary embodiment shown in Figure 2 the radial face 20 is greatly recessed relative to the centring ring 21 around which the wheel has to be fitted. This exemplary embodiment has the advantage that the axle stub 22 can remain relatively short, and the quantity of material required for the inner ring 23 is small, given the large recess. Such an embodiment is low in weight. Figure 3 shows an axial top view of the cup spring 16 of Figures 1 and 2 and surrounding construction. The cup spring 16 has a radial slit 24, while the facing ends of the cup spring 16 have recesses 25 on which a tool for spreading the cup spring 16 can engage.

Claims: Hub unit comprising a wheel bearing (1) and a driving axle stub (10, 22) which is situated in a correspondingly shaped, concentric opening (9) in the rotatable ring (3, 23) of the wheel bearing (1) and in the direction of rotation interacts by means of unround shapes (11, 12) with said ring (3, 23), which driving axle stub (10, 22) has an axle end (13) projecting from the opening (9) in said ring, characterized in that the axle end interacts with the inner periphery of a cup spring (16) whose outer periphery is supported under pre-tension on said ring (3, 23). Hub unit according to Claim 1, in which the cup spring (16) is accommodated in a peripheral groove (15) provided in the axle end (13). Hub unit according to Claim 1 or 2, in which the cup spring (16) has a radial cut (24). Hub unit according to Claim 1, 2 or 3, in which the cup spring (16) is supported on an essentially radially running face (14, 17, 20) of said ring (3, 23). Hub unit according to one of the preceding claims, in which the driving axle stub (10, 22) is accommodated in an opening (9) formed in the inner ring (3, 23), and the cup spring (16) is supported on a face (14, 17, 20) of said inner ring (3, 23) which is staggered inwards. Hub unit according to one of the preceding claims, in which the driving axle stub (10, 22) is provided with a shoulder (18) at a distance from the axle end (13), which shoulder (18) is supported on the side of the rotatable ring (3, 23) facing away from the cup spring (16). Hub unit according to one of the preceding claims, in which the driving axle stub (3, 23) is part of a constant-velocity joint. Hub unit according to one of the preceding claims in which at least one the edges (26, 27) of the cup spring (16), which are facing away from each other in the axial direction, is bevelled. Process for assembling a hub unit according to one of the preceding claims, comprising the steps of sliding the rotatable ring (3, 23) of a wheel bearing (1) over a driving axle stub (10, 22) until the axle end (13) projects from the opening in said ring (3, 23), sliding a cup spring (16) over said axle end (13) until its outer periphery abuts said ring (3, 23), preloading said ring (3, 23) by further sliding its internal periphery over said axle end (13), until said internal periphery snaps behind an abutment on the axle end (13), which abutment faces the ring (3, 23).

Inventors: HOLSNIJDERS JOZEF JOHANNES, KOLLAARD NICOLAAS, HOLSNIJDERS, JOZEF JOHANNES, KOLLAARD, NICOLAAS
Applicants: SKF IND TRADING & DEV, SKF INDUSTRIAL TRADING & DEVELOPMENT CO, B.V.
Application year: 1995
Main classification: B60B27
IPC codes: B60B27, F16B41, F16B21