Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-01-18
2001-09-04
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C310S232000
Reexamination Certificate
active
06283638
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a method of manufacturing an electrical slip ring assembly, and more particularly, the present invention is directed to a slip ring having an integral bearing used in an electrical slip ring assembly.
BACKGROUND OF THE INVENTION
A prior art capsule assembly
10
is depicted in FIG.
1
. The capsule assembly
10
includes a slip ring
12
, a pair of semi-circular brush blocks
14
and a cylindrical housing
16
. The capsule assembly
10
is formed by placing the pair of brush blocks
14
around the slip ring
12
and then the assembly of the brush blocks
14
and the slip ring
12
are placed within the housing
16
.
The slip ring
12
has a body formed from two separate members including a ring and lead member
18
(rings
24
and leads
34
) joined to a backshaft member
20
. The slip ring
12
includes an elongated cylindrical ring portion. Positioning the ring members
18
are radially extending portions
26
made of an electrically non-conductive material which separate the electrically conductive rings
24
. Each of the brush blocks
14
has a plurality of brushes
28
which are each in mechanical contact with a corresponding ring
24
. A front bearing
30
is mounted on the slip ring member
12
and a backshaft bearing
32
is mounted to the backshaft member
20
.
The backshaft member
20
extends outwardly from the housing
16
. The backshaft member
20
is grasped and rotated by another component (not shown). The slip ring
12
rotates within the brush blocks
14
and the brushes
28
from brush blocks
14
contact the rings
24
on slip ring
12
so that signals to/from the rotating slip ring
12
can be communicated to/from stationary brush blocks
14
in a known manner.
As depicted in
FIGS. 1 and 2
, the backshaft bearing
32
has one side thereof in contact with a front flange
36
formed on backshaft member
20
. The opposite side of backshaft bearing
32
is retained by a standard retainer such as a retaining clip
38
or the like. The retaining clip
38
has its inner periphery positioned in a groove (not shown) on back shaft member
20
and depending on manufacturing tolerances, the backshaft bearing
32
may not be fully restrained in an axial (longitudinal) direction or may be too tightly retained resulting in stress on the bearing. The disadvantage is that there is some play allowing the back shaft bearing
32
to move back and forth in an axial direction.
Further, the backshaft member
20
and ring member
18
must not rotate relative to each other. The backshaft member
20
and the ring member each have mating hexagonal portions. As depicted in
FIG. 3
, backshaft member
20
has a female hexagonal portion
42
which mates with a male hexagonal portion
40
on ring member
18
. The disadvantage is that this two piece construction is time consuming and expensive because two parts must be injection molded. An additional disadvantage is that the wires
34
must be potted to seal the wires
34
to the backshaft member
20
resulting in additional cost.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a method for manufacturing a slip ring with an integral bearing.
It is another object of the present invention to provide a slip ring with a back shaft bearing in which axial movement of the back shaft bearing is prevented or minimized.
It is yet another object of the present invention to provide a slip ring having a one-piece body.
It is another object of the present invention to encapsulate wires attached to the rings with in the slip ring body and eliminate potting of the wires.
It is yet a further object of the present invention to provide a slip ring which is cost effective to produce and reliable in operation.
These and other objects of the present invention are achieved by inserting electrically conductive rings and a bearing into a mold before a slip ring body is injection molded. During the injection molding process, the rings and the bearing are partially encapsulated by the injected plastic and retained. Plastic is prevented from entering the race of the bearing by using a pair of additional plastic inserts which prevent plastic from entering the bearing race. When the injected plastic cools, the plastic shrinks and compresses the bearing thereby preventing axial movement. Wires attached to the rings are also encapsulated by the plastic material during the injection molding process.
The foregoing objects are also achieved by a method of assembling a slip ring with an integral bearing. The bearing is placed in a mold. Rings are placed in a mold. A slip ring body is molded while mold material is prevented from entering the race of the bearing.
The foregoing objects are also achieved by a method of assembling a slip ring with an integral bearing. A pair of inserts are formed. A plurality of rings are secured between the pair of inserts. One or more wires are attached to each of the rings with one end of each wire extending beyond the pair of inserts. A bearing is placed between the pair of inserts. The thus assembled inserts, rings, wires and bearing form an assembly. The assembly is then inserted into a mold. A slip ring body is molded in the mold. During the molding step, the rings, the wires and the bearing are captured to form the slip ring with integral bearing.
The foregoing objects are also achieved by an integral slip ring. The slip ring includes slip ring body having a slip ring section, a backshaft section and a bearing mounting section therebetween. The bearing is mounted in the bearing mounting section wherein the slip ring body has opposed bearing retaining walls which capture the bearing and prevent axial movement of the bearing.
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description thereof are to be regarded as illustrative in nature, and not as restrictive.
REFERENCES:
patent: 2322011 (1943-06-01), French
patent: 2551030 (1951-05-01), Madden
patent: 2786985 (1957-03-01), Meretey
patent: 2854647 (1958-09-01), Nugent
patent: 3289140 (1966-11-01), Slack
patent: 4684179 (1987-08-01), Freeman
patent: 4837920 (1989-06-01), Sweet et al.
patent: 4848938 (1989-07-01), Haas et al.
patent: 5054189 (1991-10-01), Bowman et al.
patent: 1926219 (1970-11-01), None
patent: 0618648A (1994-10-01), None
patent: 707629 (1954-04-01), None
Beeken Thomas H.
Feuer, Jr. Henry O.
Grissom Donald L.
Footland Lenard A.
Litton Systems Inc.
Lowe Hauptman & Gilman & Berner LLP
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