Bearings – Rotary bearing – Plain bearing
Patent
1999-06-17
2000-10-31
Wright, Dirk
Bearings
Rotary bearing
Plain bearing
F16C 2702, F16C 2706
Patent
active
061391905
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved design of shaft bearing having particular relevance to a bearing for a steering column in an automotive vehicle.
A steering column includes all of the elements necessary to enable motions of a steering wheel to be transmitted to a steering rack. A column includes a mounting tube attached to a vehicle passenger cell in which a shaft linking together the steering wheel and the rack is guided in rotation. The shaft is supported in the mounting tube by a number of bearings. In many cases, the mounting tube is constructed from a steel tube on which are fixed flanges for attachment to the passenger cell. In some cases the mounting tube is diecast from aluminium and the surfaces for supporting the mounting are machined.
It is known to support and guide the shaft inside the mounting tube by means of needle bearings and ball bearings. Known needle bearings are described in and known from EP 0 554 144 A1. Another known bearing for this purpose is described in EP 0 448 847A1.
When used in steering columns, bearings must satisfy a number of conditions. Car manufacturers specify the mounting, speed and temperature conditions in which the bearings must operate. Bearings must also allow steering wheel stresses to be transmitted via the shaft axis and must run silently. Further, the bearings must keep their properties during the life of the steering column despite the various environmental factors encountered, including the levels of temperature, humidity and grease.
Needle bearings can be expensive to manufacture. It is an advantage of the present invention that it provides for less expensive manufacture of a bearing assembly but provides for similar levels of life and safety.
According to a first aspect of the invention we provide a bearing assembly comprising a bearing having an axial split and an antifriction lining, and an elastic element, the elastic element exerting a force on the bearing acting to close the axial split, the elastic element comprising an elastomeric crown, in which the elastomeric crown is held in relation to the the bearing by a bead on the crown located in the split in the bearing.
This is one of two principal ways in which a continuous pressure may be maintained on the rear surface of the bearing. In this first way, the force on the bearing is applied to the shank of the bearing by compression of an elastic element between the bearing and the housing in which it is located. In such a case, the force exerted will follow the intrinsic physical characteristics of the elastic element, and will be affected by any irregularities on the inside surface of the housing. In a second way, the pressure on the bearing is generated solely by the elastic element. In such a case, the pressure exerted is more uniform since it is not affected by any irregularities on the inside surface of the housing. Also, such a method does not depend upon the clearances between the shaft and the housing.
In a first embodiment the bearing also comprises radially outwardly directed flanges. Alternatively the elastomeric crown may be held in relation to the bearing by a number of bosses spaced about the periphery of the bearing.
According to a second aspect of the invention, a bearing assembly comprises a bearing having an axial split and an antifriction lining, and an elastic element, the elastic element exerting a force on the bearing acting to close the axial split, the elastic element comprising a shaped tube of alternating concave and convex portions, in which the shaped tube is held in axial relation to the bearing by a groove provided on the outer surface of the bearing.
According to a third aspect of the present invention, a bearing assembly comprises a bearing having an axial split and an antifriction lining, and an elastic element, the elastic element exerting a force on the bearing acting to close the axial split, in which the elastic element comprises spring means located in grooves in the outer surface of the bearing. Preferably an elastomeric crown is located around the ou
REFERENCES:
patent: 2851314 (1958-09-01), Thomson
patent: 3976340 (1976-08-01), Pitner
patent: 4518205 (1985-05-01), Heathe
patent: 4600317 (1986-07-01), Mori
patent: 4895391 (1990-01-01), Groat
International Search Report mailed Apr. 17, 1998 for PCT/EP97/06952.
Dana Corporation
Wright Dirk
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