Protective device for a drive assembly with a double...

Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing – Telescoping cylindrical housing members

Reexamination Certificate

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C464S175000

Reexamination Certificate

active

06406375

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims priority to German Patent Application 199 53 463.2 filed Nov. 5, 1999, and German Patent Application 100 37 041.1 filed Jul. 27, 2000, which applications are herein expressly incorporated by reference.
BACKGROUND OF THE INVENTION
The invention relates to a protective device for a drive assembly. The drive assembly includes a double universal joint with a double yoke, a first joint yoke, a second joint yoke and a first and a second cross member. The cross members articulatably connect the first joint yoke and the second joint yoke to a first and a second yoke associated with the double yoke.
DE 30 33 850 A1 describes a protective device for a double universal joint. A protective cone is connected to bearing means supported on a joint yoke. A tubular protective element is supported on the double yoke by a bearing race. In the non-articulated condition of the joint, the protective cone covers part of the length of the tubular protective element. Both components are connected to one another by friction locking, form-fitting or connecting means. Thus, in the direction of rotation, a permanent relative movement relative to one another is avoided. However, the existing protective assembly only allows the double universal joint to be partially covered in the axial direction if easy access to the components of the double universal joint is desired.
DE-OS 20 46 236 describes a protective device for a double universal joint. The protective device includes a protective dish associated with the first joint yoke. The protective dish extends over one end of a protective element which is rotatably movably supported on the inner double yoke. The protective element covers those partial regions of the double yoke which are positioned to one side of the bearing. The protecting portion of the protective element faces away from the protective dish and projects into a protective cone. A gap occurs between the elements of the protective device when the double universal joint is articulated. The gap enables engagement from the outside. Equally, when loads generated by external forces are applied, there is no adequate resistance because the protective elements are each open on one side and can thus be deformed. In consequence, there is a possibility of contact with the rotating components of the double universal joint. This contact may result in damage to the components. Thus, the protective function to prevent contact is no longer ensured.
DE 195 41 512 C1 describes a protective device for a driveshaft. The device has two single universal joints which are connected to one another in a rotationally fast way by two profiled tubes inserted into one another. The assembly is covered by the protective device. The protective device has two protective tubes enclosing the profiled tubes and protective cones connected to their ends by means of an attaching cap. The protective cones include folds. In order to ensure the radial stability of the protective cone, even if the latter is of the soft type, a supporting ring is provided which supports the protective cone at a distance from its fixing means on the inside of the attaching cap.
EP 0969218 A1 describes a protective device for a drive assembly with a double universal joint. Here, the protective cone includes folds and is secured by its first axial end to a bearing assembly of a driveshaft. Its second axial end has a fixing portion connected to a guiding ring. The guiding ring, via its inner end, projects into that part of the protective cone which is provided with folds. The guiding ring, in turn, via a cylindrical bore, is supported on an externally spherical bearing race which is supported on the inner double yoke of the double universal joint. As a result, a relative axial movement is permitted between the guiding ring and the bearing race. However, it has been found that this kind of support does not provide the required articulation ability. Accordingly, in view of the inadequately defined conditions of movement carried out by the protective cone with its folds and the guiding ring attached thereto relative to the bearing race, the amount of wear increases. In particular, wear occurs in the region of contact between the cylindrical bore of the guiding ring and the spherical outer face of the bearing race. In practical terms, a line contact exists. However, the advantage of this assembly is that a relatively long protective cone region exists with the folds. This leads to the ability to accommodate larger articulation angles.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a protective device for a drive assembly having a double universal joint. The protective device covers the rotating parts of the double universal joint. The protective device covers the rotating parts of the double universal joint and enables easy access to the double universal joint for maintenance work, while featuring a long service life.
In accordance with the invention, a protective device includes a plastic protective cone with a first axial end, a second axial end and folds therebetween. The protective device, at least in the axial direction, enables elastic deformation. The first axial end of the protective cone serves to be releasably connected to a bearing assembly at the first joint yoke. The second axial end serves as a fixing portion. A bearing race is rotatably supported around a rotational axis at the double yoke. The bearing race is positioned in the protective cone and includes a spherical outer bearing face. A guiding ring has an inner bearing face in the form of a hollow-spherical zone. The guiding ring has a first opening facing the first axial end and a second opening facing away from the first opening. The second opening has an opening cross-section which, at its maximum, corresponds to the sphere diameter of the inner bearing face. The first opening has a diameter which is smaller relative to the second opening. The first opening is further offset from the center of the hollow-spherical-zone-like inner bearing face towards the first axial end than the second opening. The second opening is either positioned in a plane containing the center of the inner bearing face or is also offset therefrom towards the first axial end. The guiding ring is connected to the second axial end of the protective cone. The protective cone, via the folds of the protective cone and its inner bearing face, is held so as to be pre-tensioned into contact with the outer bearing face of the bearing race.
The protective device is complemented by the protective dish which is usually provided at the tractor or at the implement. The protective device partially projects into the dish. The advantage of this inventive design is that, under articulation, the calotte-like support provided for the guiding ring ensures clearly defined conditions of movement for the protective cone with its region provided with folds. Furthermore, clearly defined conditions of movement for the guiding ring exists relative to the bearing race in the sense of a spatial movement of the spherical or hollow-spherical faces. This is due to the fact that the faces are always in contact with one another as a result of being loaded by the folds of the plastic convoluted boot. In addition, a surface contact is achieved which clearly reduces the amount of wear and results in a correspondingly long service life of the protective device. It is possible to achieve a long length provided with folds so that even if one takes into account the spatial movement which the guiding ring is able to carry out relative to the bearing race, large articulation angles are possible. As a result of the pre-tension, that part of the protective cone which is provided with folds is sufficiently supported, thus ensuring a high degree of radial stability.
Furthermore, access to individual components, a lubricating nipple for lubricating the centering means or the cross member bearings of the double universal joint, is provided by release or displ

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