Center bearing for a shaft

Details Center bearing for a shaft Center bearing for a shaft

1998-12-11

2001-10-02

Bucci, David A. (Department: 3682)

Bearings

Rotary bearing

Antifriction bearing

C440S083000

Reexamination Certificate

active

06296394

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a center bearing for a shaft, and more particularly to a center bearing for a propeller shaft.
RELATED TECHNOLOGY
A center bearing is disclosed in U.S. Pat. No. 2,893,790. A disadvantage of this center bearing, however, is that an axial motion of the shaft can be absorbed in only very limited fashion. The physical design of the bearing does not provide for the absorption of greater axial forces or displacements.
German Patent Publication No. 26 29 393 A1 describes another center bearing. Although greater axial motions can be absorbed within this rolling bearing than with the bearing disclosed in U.S. Pat. No. 2,893,790, such motions nevertheless are limited because of the arrangement of the sealing elements. Another disadvantage with this center bearing is the use of cylindrical roller bearings, since this bearing configuration cannot be loaded when the shaft is at a standstill, and the presence of a load leads to chatter marks on the bearing guiding surfaces. With this center bearing, moreover, it is extremely difficult or impossible for design reasons to use a bearing configuration other than cylindrical roller bearings.
A further center bearing is disclosed in German Patent Publication No. 24 57 941. In this, a toothed toroidal ring is arranged between an inner element surrounding the rolling bearing and an outer element surrounding the inner element. The ring is said to be able, by rolling on the inner and outer elements, to absorb axial as well as tilting and radial forces.
Compensation for axial and tilting forces by rolling of the toothed and thus positively engaged toroidal ring is disadvantageous, however, since a dependency between the radial and axial stiffness of the entire shaft bearing results. For example, if a change occurs in the axial stiffness of the shaft bearing—resulting from a modification, for example, of the material, the size, or the tooth pattern of the toroidal ring—then the radial stiffness or tilting stiffness is automatically also influenced.
In addition, the shaft bearing described therein presents a resistance to any tilting force which occurs; this is in fact not desirable, however, since this tilting motion is in any case compensated for by the propeller shaft or cardan shaft.
German Patent Utility Model No. 81 00 855 describes a bearing arrangement for elastic bracing of a rotating shaft, in which an annular element manufactured from a resilient material is attached directly onto the outer ring of the rolling bearing.
The configuration depicted there also, however, has the disadvantage already described above, of dependency between radial and axial stiffness.
German Patent No. 83 09 873 D1 discloses a rod end bearing sealed with a sealing sleeve.
SUMMARY OF THE INVENTION
An object of the present invention to create a center bearing for a propeller shaft with which very large axial motions of the shaft can be absorbed.
The present invention provides a center bearing for a shaft, in particular a propeller shaft, comprising a rolling bearing arranged on the propeller shaft and comprising a bearing housing surrounding the center bearing. A slide ring (
3
) in which the rolling bearing (
2
) is axially displaceable is arranged over the outer periphery of the rolling bearing (
2
); and a decoupling element (
4
) is arranged between the slide ring (
3
) and the bearing housing (
5
). A dust protection bellows (
7
) is arranged around the rolling bearing (
2
) and the slide ring (
3
)
As a result of the fact that the rolling bearing can absorb forces in the axial direction because it is axially displaceable on the slide ring, axial forces are no longer passed on to the decoupling element. The decoupling element therefore needs to absorb only tilting motions, and can advantageously be physically designed very precisely for a specific radial stiffness, without thereby influencing the axial stiffness of the entire center bearing.
Axial displacement of the shaft is absorbed by a sliding motion of the rolling bearing on the slide ring. Because of this sliding motion, the axial stiffness of the center bearing is very low, so that even very small forces occurring during operation are no longer passed on to the shaft. The axial displacement travel of the rolling bearing on the slide ring can be of any desired magnitude.
This axial displacement travel is ensured by the arrangement, according to the present invention, of the dust protection ring between the roller bearing and the slide ring, since the latter participates in the axial motion of the rolling bearing with respect to the slide ring.


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