Note: Descriptions are shown in the official language in which they were submitted.
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CONNECTOR FOR ARMORED ELECTRICAL CABLE
BACKGROUND OF THE INVENTION
PATENT
1. Field of the Invention
This invention relates to connectors for
electrical cables, and, more particularly, to connectors
for attaching armored electrical cables to metal
enclosures.
2. Brief Discussion of Related Art
Armored electrical cable is used for a wide
variety of applications. The electrically conductive armor
enables the cable to be grounded over its entire length.
The armor also protects the conductors of the cable from
damage resulting from abrasion and the like. An outer
plastic or rubber sheath may be provided over the armor to
waterproof and further protect the cable. When permitted
by applicable electrical code, armored cable may be used in
place of rigid conduit. Rigid conduit is typically more
difficult to install than the more flexible armored cable.
In addition, rigid conduit is often more expensive than
comparably sized armored cable.
When armored cables are connected to, or
terminated in, metal enclosures, special connectors are
typically used. Often, such connectors are required by the
applicable electrical code. The connectors provide
electrical grounding continuity between the cable armor and
the enclosure, resistance to undesirable withdrawal of the
cable from the enclosure, and moisture and dust resistance
in the area where the cable is connected to the enclosure.
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Existing armored cable connectors are bulky in
size. Those connectors may require tightening of three or
more threaded parts for complete installation of the
connector, which increases installation time and
complexity. Such connectors are complex and relatively
expensive to manufacture because of the number of
components. The prior art armored cable connectors are
also quite limited as to the range of cable sizes that can
be accommodated using a given size connector.
There is a need for a connector for an armored
cable which permits simpler and less expensive
construction, accommodates a greater range of cable sizes
for a given size of connector, and is simpler and quicker
to install.
SUMMARY OF THE INVENTION
This invention has met the above described needs.
The armored cable connector of this invention includes a
body of unitary construction, and a cap. The body has a
generally longitudinal opening extending therethrough. The
cap includes a first open end to receive at least a portion
of the body therein and a second end being open to receive
the cable therein. A first end of the body has an inwardly
beveled surface thereon. The second end of the body has
connecting means thereon to attach the connector to another
structure, such as a metal enclosure. An electrically
conductive circular spring is positioned inside the cap to
be in electrical contact with the armored cable and the
body. A ring washer is positioned inside the cap between
the spring and the second end of the cap. A first end of
the ring washer is beveled generally inwardly to engage and
wedge the spring into mechanical contact with the armored
cable to secure the armored cable to the connector and to
provide an electrical connection between the cable armor
and the connector body. Engaging means, such as for
example screw threads, compressively engage the cap and the
connector body to effect this wedging action.
Sealing means may be positioned inside the cap
between the ring washer and the second end of the cap. The
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ring washer may also be provided with an inwardly beveled
second end to wedge the sealing means into sealing
engagement with the armored cable as the cap is applied to
the connector body.
It is an object of this invention to provide an
armored cable connector for securing armored cable to a
metal enclosure.
It is another object of this invention to provide
a connector for an armored cable which provides improved
electrical grounding continuity, moisture resistance, and
cable pullout resistance.
It is yet another object of this invention to
provide an armored cable connector which is relatively
simple to use and install.
It is still another object of this invention to
provide an armored cable connector that is relatively
simple and relatively inexpensive to manufacture.
It is another object of this invention to provide
an armored cable connector that will accommodate a large
range of cable sizes for a given connector size.
These and other objects will be more fully
understood from the following description of the preferred
embodiment, the drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a longitudinal sectional view of a
preferred embodiment of the armored cable connector of this
invention taken through the center of the connector and
showing the connector prior to installation of a cable.
Figure 2 is a longitudinal sectional view of a
preferred embodiment of the armored cable connector of this
invention taken through the center of the connector and
showing a cable installed therein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In Figures 1 and 2, there is shown the armored
cable connector 2 of this invention. Connector 2 includes
connector body 4, cap 6, electrically conductive spring 8
and ring washer 10. An armored cable 3 with which
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connector 2 is used is shown in Figure 2. Cable 3 includes conductors 5
encased in electrically conductive armor 7. Armor 7 may be covered by a
plastic or rubber sheath 9.
With reference to Figures 1 and 2, body 4 is of generally unitary
construction and is made of electrically conductive material, such as
aluminum or zinc-plated steel. A generally longitudinal opening 12
extends through the center of body 4. A first end 14 of body 4 has surface
16 thereon. Surface 16 is beveled generally inwardly toward opening 12.
A second end 18 of body 4 has connecting means 20 thereon to attach
body 4 to another structure (not shown). In a preferred embodiment,
connector means 20 includes external threads 22 to engage cooperating
threads on the structure to which body 4 is to be attached. Examples of
types of structures to which connector 2 may be attached include junction
boxes, panel boards, motor control enclosures, electrical distribution
equipment, and the like.
Cap 6 is positioned over first end 14 of body 4. First end 30 of cap 6
is open and at least a portion of body 4 is received therein. Preferably, the
portion of body 4 received into cap is a portion extending axially from
first end 14. A second end 32 of cap 6 has an opening 34 to receive
armored cable 3 (Figure 2). Cap 6 is preferably made from an electrically
conductive material, such as the same type of material from which body
4 is made.
A central axis (not shown) extends through the second end 18 of
body 4 and second end 32 of cap 6.
A generally circular, electrically conductive spring 8 is positioned
inside cap 6. Spring 8 is positioned to be in mechanical and electrical
contact with connector body 4 and armored cable 3. Preferably, spring 8
will be in electrical contact with armor 7 of cable 3. If necessary to expose
armor 7, a portion of sheath 9 may be removed to provide electrical
continuity for grounding the armor 7 through the connector. In a
preferred embodiment, spring 8 is retained in recess 35 in cap 6 during
assembly of connector 2. Spring 8 is preferably a coil spring made out of
non-magnetic stainless steel. It will be
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appreciated, however, that spring 8 may be made out of any suitable
conductive material.
Ring washer 10 is positioned inside cap 6 between spring 8 and
second end 32 of cap 6. Ring washer 10 has a first end 38 which has a
generally inwardly beveled surface 40 thereon. Beveled surface 40 is
inclined at a relatively large angle to the central axis. Beveled surface 40
is positioned to engage spring 8 into mechanical and electrical contact
with cable 3 and connector body 4. The retention of spring 8 in recess 35
will hold ring washer 10 inside cap 6 during assembly of connector 2.
Engaging means 42 are provided for compressively connecting cap
6 and body 4. In a preferred embodiment, engaging means 42 includes
threads 44 on an inner surface of cap 6 positioned to engage cooperating
threads 46 on an outer surface of body 4.
In a preferred embodiment, seal 47 is positioned inside cap 6
between second end 32 of cap 6 and ring washer 10. Seal 47 sealingly
engages cap 6 and armored cable 3. Such engagement provides a
watertight and dust-tight seal where cable 3 enters connector 2.
Preferably, seal 47 includes flexible O-ring 48. O-ring 48 is preferably
made of neoprene or another suitable material. A second end 50 of ring
washer 10 has a generally inwardly beveled surface 52 thereon. Beveled
surface 52 is inclined at a relatively small angle to the central axis.
Beveled surface 52 engages and wedges O-ring 48 into sealing
engagement with armored cable 3 and cap 6. In preferred embodiment,
cap 6 includes a generally inwardly projecting shoulder 54 positioned to
engage O-ring 48. O-ring 48 is preferably positioned to engage the plastic
or rubber sheath 9 of cable 3. In a preferred embodiment, O-ring 48 is
retained in recess 55 during assembly of connector 2. While it is
preferred to use a flexible O-ring as seal 47, it will be appreciated that any
suitable seal may be used, such as a cylindrical sealing washer, for
example.
Referring more particularly to Figure 2, to attach an armored cable
3 to an enclosure or other structure (not shown), connector body 4, with
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cap 6, spring 8, ring washer 10 and O-ring 48 all relatively loosely
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enclosure using threads 22. Armored cable 3 is inserted through opening
34 in cap 6 and into opening 12 in connector body 2. In a preferred
embodiment, opening 12 through body 4 includes a large diameter
portion 56 and a small diameter portion 58 connected by a beveled cable
stop 60. Large diameter portion 56 extends from first end 14 to cable stop
60 and small diameter portion 58 extends from cable stop 60 to second
end 18. The free end of cable 3 inserted into connector 2 abuts cable stop
60. Preferably, the end of armor 7 will abut cable stop 60. It will be
appreciated that the outer diameter of armor 7 of cable 3 will preferably,
but not necessarily, be larger than the diameter of small diameter portion
58 of opening 12. The conductors 5 of cable 3 extend past cable stop 60,
through small diameter portion 58 and exit connector 2 through second
end 18. Once cable 3 is fully inserted, cap 6 is tightened, thereby
compressing spring 8, ring washer 10 and O-ring 48 to ensure the desired
electrical connection and seal discussed above. In addition, the
compression of spring 8 between beveled surface 16 of body 4 and beveled
surface 40 of ring washer 10 pushes spring 8 against cable 3, which holds
cable 3 tightly within connector 2 thereby increasing cable pullout
resistance.
It will be appreciated that once connector 2 is in place in the
enclosure, only cap 6 needs to be tightened to provide the necessary
compression to achieve the desired electrical connection, dust and water
seal and cable pullout resistance. In addition, the beveled surfaces of
connector body 4 and ring washer 10 permit generally inward movement
of spring 8 and O-ring 48, thereby allowing a range of cable sizes to be
accommodated in a connector of a given size.
In a preferred embodiment, body 4 and cap 6 are formed from
generally hexagonal or octagonal stock. Parts are preferably machined in
a manner well known to those skilled in the art. Forming of threads 22
and 44, 46, and the desired openings can be done while leaving portions
of the hexagonal or octagonal stock intact as locations where
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the connector may be engaged for tightening the connector
into the enclosure and/or tightening cap 6 onto body 4.
It will be appreciated that the connector for an
armored cable of this invention provides electrical
grounding continuity, water and dust resistance, and cable
pullout resistance while being relatively simple to
manufacture and install.
Whereas, particular embodiments of this invention
have been described for purposes of illustration, it will
be evident to those skilled in the art that numerous
variations may be made without departing from the invention
as described in the claims.
