Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1998-12-28
2001-02-27
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C464S178000, C384S539000
Reexamination Certificate
active
06193419
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a wheel hub/constant velocity joint unit having a double-row bearing assembly arranged on the wheel hub and comprising at least one separate inner bearing ring pointing towards the constant velocity joint. The invention also covers wheel hub/constant velocity joint units comprising two inner bearing rings separated from and slid on to the wheel hub. In both cases, the outer bearing ring is undivided, as usual, and inserted directly into a wheel carrier.
As known in the state of the art, it is necessary for the two symmetrically arranged rows of bearings of the bearing assembly designed as angular contact deep groove bearings to be fitted with a pretension to ensure that, in view of the cyclic loads acting on the wheel, the bearings are play-free.
DE 36 18 139 A1 describes a unit of the above-mentioned type wherein an annular member is connected to the wheel hub by friction welding. The friction weld provides the pretension of the separate inner bearing ring at the joint end relative to the wheel hub. The inner bearing ring is completely embedded in the material of the wheel hub. In this embodiment, there are problems in accurately setting the pretension, as the pretension builds up by the friction weld that still flows after the friction welding operation. The dimensions of the friction weld change during the cooling process. As a result, the remaining pretension at the bearing assembly still changes at the end of the friction welding operation.
A non-rotating, form-fitting connection between the annular member and the outer joint part is achieved by inter-engaging end teeth which are tensioned by a bolted connection between the wheel hub and the outer joint member. Even with slight axial settlement symptoms, the connection is no longer play-free and is not suitable for the present unit.
From DE 36 08 346 A1 it is known to connect the outer joint part of a unit of the above-mentioned type directly with the wheel hub by friction welding. A collar of the outer joint part, is positioned radially outside tie friction weld, providing axial support between the outer joint part and the separate inner bearing ring at the joint end. Again, there are problems accurately setting the pretension because during the cooling process following the friction welding operation the axial dimension still changes. The remaining pretension at the bearing assembly hence changes at the end of the friction welding operation. The degree of change first has to be determined empirically, with the degree of scatter for welding operations being greater than for purely mechanical production process or cold-forming operations.
There is a further disadvantage in that the friction welding operation referred to has to be carried out before the constant velocity joint is finally assembled. The assembly procedure for the constant velocity joint thus must use a complete unitary constant velocity joint, wheel hub and bearing. This requirement complicates the procedure.
EP 0 610 782 A1 describes a unit of the type wherein the separate inner bearing ring at the joint end is axially tensioned on the wheel hub by a formed sleeve member. The sleeve member is integrally formed or slides on separately. Subsequently, the outer joint part typically is directly connected to the wheel hub by inter-engaging teeth and a securing ring.
With this embodiment, each time the wheel hub or bearing design is changed, the design of the outer joint part has to be adapted accordingly. This means that the manufacturer has to produce a large number of joint embodiments.
It is the object of the invention to provide a unit of the initially mentioned type wherein the method of tensioning the bearing assembly and the joint assembly procedure are improved.
SUMMARY OF THE INVENTION
The objective is achieved by an outer joint part comprising a central inner aperture which points towards the wheel hub and inner teeth. An annular member is non-rotatingly inserted into the inner teeth, and produced separately from the wheel hub. The annular member includes outer teeth. The outer joint part and the annular member are connected by a removable axial connecting means. The annular member is connected to the wheel hub by a non-destructively non-removable connecting means. The non-removable connecting means provides the pretension for the bearing assembly. On the one hand, this embodiment allows the joint to be assembled with the outer joint part still separated from the wheel hub, i.e. it is possible to apply conventional assembly methods, either manual or automated, without making any changes or adaptations. On the other hand, it is possible to tension the bearing assembly by an annular member which is easy to handle. In addition, independent of the type of connecting means used between the annular member and the wheel hub, the bearing assembly can always be held under pretension while the connection is in the process of being produced. The material of the annular member is advantageously independent of the requirements to be met by the material of the outer joint part. For example, it is possible to take into account improved weldability or improved cold-formability, depending on the type of connecting means selected for the connection that cannot be unfastened.
The term “annular member” also refers to annular elements having an inner aperture with a radial supporting wall, so the element does not have a free axial passage.
As a result of the removable connecting means, it is possible to replace a damaged bearing or a damaged constant velocity joint. This is advantageous with respect to the cost of manufacturing. The non-removable connecting means ensures that the pretension of the bearing is maintained at a uniform level, even when the constant velocity joint is replaced.
Further, it is possible to vary either the bearing dimensions or the joint dimensions, without having to change the dimensions of the other part that is not affected. Any adaptation measure may refer entirely to modifying the annular member. This refers to the possibility of retaining certain joint sizes or designs while carrying out modifications in the region of the bearing assembly. For example, by designing the wheel carrier in different ways, it is also possible to use different joint sizes, while leaving the bearing assembly unchanged, in a vehicle model with different engine output variants.
The preferred connecting means between the inner teeth of the outer joint part and the outer teeth of the annular member consists of annular grooves associated with one another in the region of the teeth sets. A securing ring is inserted into the grooves for axial security. According to a preferred embodiment, the annular grooves and the securing ring comprise a rectangular cross-section. The securing ring engages the annular groove in the outer joint part under pretension and the annular groove in the annular member comprises radial play for fitting the ring. In this way, it is possible to produce a connection which is particularly suitable for accommodating the axial forces that occur. Modifications of the above are possible. For instance, it is possible to provide a double assembly of securing rings which engage the annular groove in one of the parts and rest against end contact faces of the respective other one of the parts.
Additional embodiments are possible for the connecting means between the annular member and the wheel hub. The connecting means at the same time ensures the pretension in the double-row bearing assembly. This characteristic makes it possible for the annular member to be separate from at least one separate inner bearing ring on the wheel hub, but also for the annular member integral with at least one separate inner bearing ring on the wheel hub.
In the case of both the above-mentioned embodiments it is possible to slide the annular member onto a centering collar at the wheel hub and for a weld to be formed in an axially extending longitudinal gap between the annular member and the centering collar.
A second possibili
Frielingsdorf Herbert
Krude Werner
GKN Automotive AG
Hannon Thomas R.
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