Spring devices – Vehicle – Torsion
Reexamination Certificate
1997-11-13
2001-01-09
Schwartz, Christopher P. (Department: 3613)
Spring devices
Vehicle
Torsion
C267S141200, C267S141400, C267S293000
Reexamination Certificate
active
06170812
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to bushings, and more particularly to slipper bushings, which are used in automobile suspension systems and which provide relative rotation between inner and outer cylindrical members of the bushing by way of slippage between mating surfaces of the inner and outer members.
BACKGROUND OF THE INVENTION
As its name implies, a slipper bushing utilizes slippage between mating surfaces of the nonrotatably fixed and rotatable portions of the slipper bushing as a means to permit controlled rotational movement therebetween. Often a lubricant, which may be contained in grooves in one or the other of the mating surfaces, is utilized to lubricate those surfaces in order to decrease the break away torque, i.e. the torque required to overcome the circumferential frictional force between the mating surfaces. It is desirable, therefore, to include an end cap on each axial end of the slipper bushing, which end cap includes an annular flange portion covering the interface of the mating surfaces, in an attempt to eliminate as much as possible any contaminants, for example dirt and the like, from entering into the bushing between the slip surfaces, since such contamination would thereby contaminate the lubricant thereon and undesirably increase the break away torque. One example of such a bushing is disclosed in Chakko U.S. Pat. No. 5,139,244, assigned to the assignee of the present invention, and hereby incorporated by reference herein as if fully set forth in its entirety.
While such a slipper bushing design can prevent at least some of the contaminants, to which a bushing is subjected in its operating environment, from entering therein, improvements in slipper bushing sealing techniques are desirable. However, any such improvements must not increase the break away torque of the slipper bushing to undesirable levels.
SUMMARY OF THE INVENTION
In accordance with the present invention, a slipper bushing comprises a radially inner generally cylindrical member, a radially intermediate generally cylindrical member including an axial bearing surface at an end thereof, a radially outer generally cylindrical member and elastomeric material disposed between the intermediate and outer cylindrical members. A generally cylindrical polymeric radial bearing sleeve is disposed between the inner and intermediate cylindrical members. The radial bearing sleeve has a radially inner surface nonrotatably fixed relative to a radially outer surface of the inner member and a radially outer slip surface adapted to rotatably slip relative to a radially inner surface of the intermediate member. An elastomeric seal has an annular portion with opposed first and second axial bearing surfaces. The seal first axial bearing surface sealingly engages the intermediate member axial bearing surface and is nonrotatably fixed relative thereto. An annular polymeric slip ring has opposed first and second axial bearing surfaces. The slip ring first axial bearing surface is adapted to rotatably slip relative to the seal second axial bearing surface. An end cap is nonrotatably fixed relative to the inner member and the slip ring.
The bushing further comprises a cylindrical ring with the seal being fixed to the ring. The seal further includes a cylindrical portion having radially inner and outer surfaces. The seal cylindrical portion radially inner surface is fixed to a radially outer surface of the cylindrical ring. The intermediate member has an inner diameter, and the cylindrical ring and seal cylindrical portion are press fitted into the inner diameter of the intermediate member. The cylindrical ring is preferably fabricated of drawn steel and the seal is preferably fabricated of rubber mold bonded to the drawn steel ring.
The slip ring has an inner diameter and the inner member has an outer diameter. The slip ring inner diameter is press fitted onto the inner member outer diameter. The slip ring is preferably fabricated of nylon.
The elastomeric material is preferably fabricated of rubber mold bonded to the intermediate sleeve.
The end cap includes a cylindrical portion and the inner member has an inner diameter. The end cap cylindrical portion is press fitted into the inner member inner diameter. The end cap includes an annular portion having an axial bearing surface engaging the slip ring second axial bearing surface and is nonrotatably fixed relative thereto.
The radial bearing sleeve is preferably fabricated of nylon mold bonded to said inner member.
The present invention is likewise applicable to the design and construction of non-duplex bearings, i.e. bearings with only two (inner and outer) cylindrical members. In this aspect of the invention, a slipper bushing comprises a radially inner generally cylindrical member, a radially outer generally cylindrical member including an axial bearing surface at an end thereof and a generally cylindrical polymeric radial bearing sleeve disposed between the inner and outer cylindrical members. The radial bearing sleeve has a radially inner surface nonrotatably fixed relative to a radially outer surface of the inner member and a radially outer slip surface adapted to rotatably slip relative to a radially inner surface of the outer member. An elastomer seal has an annular portion with opposed first and second axial bearing surfaces. The seal first axial bearing surface sealingly engages the outer member axial bearing surface and is nonrotatably fixed relative thereto. An annular polymeric slip ring has opposed first and second axial bearing surfaces. The slip ring first axial bearing surface is adapted to rotatably slip relative to the seal second axial bearing surface. An end cap is nonrotatably fixed relative to the inner member and slip ring.
The invention thus provides the advantage of added security from contaminants contaminating the slipper bushing by way of an additional seal, over and above the usual end cap, yet without suffering from a substantial increase in break away torque of the slipper bushing.
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BTR Antivibration Systems, Inc.
Schwartz Christopher P.
Williams Thomas J.
Wood Herron & Evans L.L.P.
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