Note: Descriptions are shown in the official language in which they were submitted.
PUSH-IN FITTING FOR ELECTRICAL METALLIC TUBING
WITH ENHANCED SEALING AND CONTINUITY
FIELD OF THE INVENTION
This invention relates generally to electrical
connectors or fittings for use with electrical metallic
tubing or EMT, and more specifically to a "push-in"
connector for attaching an electrical metallic tube to an
electric box or panel or for connecting one electrical
metallic tube to another electrical metallic tube.
BACKGROUND OF THE INVENTION
Various types of connectors or fittings for
connecting tubes or conduits to a structure or to one
another are known, as exemplified in U.S. Patents
4,123,090; 5,284,582; 5,695,224; 6,334,634; 6,450,550;
6,464,266; 6,517,124; 6,663,145; 6,670,553; 6,765,143 and
6,913,292. Generally, the known connectors or fittings
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are relatively complex. Many consist of a relatively
large number of component parts that require assembly
which may not be cost effective and/or practical for
their intended purpose. Further, some of the known
connectors or fittings are not suitable for use with
electrical metal conduits or tubes. Notwithstanding the
extensive background relating to connectors or fittings
for connecting tubular conduits, continuing efforts are
being made to improve, simplify and/or to enhance the
efficiency and/or use of such connectors or to simplify
the assembly, cost and/or complexity of such known
connectors or fittings in an effort to advance the
connector art, and more specifically to advance the
electrical tube connector art. The disclosure herein is
directed to such efforts.
SUMMARY OF THE INVENTION
An object of this invention is to provide an
electrical connector or fitting for connecting an
electrical metallic tube or conduit thereto merely by
pushing an end portion of an electrical metallic tube
through the inlet opening of the electrical connector or
fitting.
Another object is to provide an electrical connector
or fitting incorporating a simple push-in locking
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arrangement for an electrical metallic tube adapted to
connect such tube to an electric box or in the form of a
coupler for joining two or more EMTs together.
Another object is to provide an electric connector
or fitting having a unidirectional locking arrangement
for securing an electrical metallic tube thereto whereby
in one form of the invention, the electrical metallic
tube can be rendered readily removable and in another
form of the invention, removal of the electrical metallic
tube is prohibited.
Another object of the invention is to provide an
electrical connector or fitting having a simplified
locking and sealing arrangement to which an electrical
metallic tube or conduit may be positively secured
thereto simply by pushing the end portion of an
electrical metallic tube through the inlet opening of the
connector or fitting.
Another object of this invention is to provide a
locking device constructed and arranged to effect a
positive unidirectional gripping force on an associated
electrical metallic tube with an arrangement for
retaining the locking device within the body of a
connector to prohibit any unintentional separation
thereof from the connector body.
Another object of the invention is to provide an
electric connector or fitting having a locking device for
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securing an electrical metallic tube thereto by simply
pushing an end portion of an electrical metallic tube
through the locking device and which may be used with or
without a water, liquid or moisture seal.
A feature of the invention resides in an electrical
connector or fitting for securing an electrical metallic
tube or conduit thereto which is relatively simple to
manufacture, easy to assemble and positive in operation.
Another feature of this invention resides in a
locking or gripping device formed from a blank of spring
metal rolled into the form of a split ring having
integrally formed circumferentially spaced depending
gripping tangs and opposed integrally formed radially
inward support tangs for supporting an electrical
metallic tube adapted to be secured thereto.
It is yet another object of an embodiment of the
invention to improve sealing.
It is yet another object of an embodiment of the
invention to provide improved conductivity.
It is an advantage of the present invention that the
shape of an 0-ring seal is substantially maintained.
It is an advantage of an embodiment of the invention
that a reduced voltage drop across the electrical
connector is obtained.
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It is a feature of the present invention that
flexible gripping tangs are sufficiently spaced from the
0-ring seal so as to prevent contact with the flexible
gripping tangs.
It is a feature of an embodiment of the invention
that the connector body has internal radially extending
ribs that increase radially along an axial direction.
It is an object of an embodiment of the invention to
improve weatherproof sealing when attaching the fitting
to the electrical panel.
It is an advantage of an embodiment of the invention
that a locknut may be securely tightened to the
electrical panel without compromising the integrity of a
sealing washer.
It is a feature of an embodiment of the invention
that the flange has a contact shoulder adapted to contact
an edge of the electrical panel preventing excessive
compression of the sealing washer.
The foregoing objects, features, and advantages are
attained by an electrical connector or fitting having a
locking arrangement for enhancing the ease of connecting
an electrical metallic tube to an electric box or panel
or to connect one electrical metallic tube to another
electrical metallic tube. The connector or fitting
includes essentially a connector body having an inlet end
portion and an outlet end portion with a bore extending
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therebetween. In one form of the invention, the inlet end
portion defines an enlarged inlet forming an outermost
chamber having a predetermined diameter for receiving a
specifically constructed locking device, an intermediate
chamber having a smaller diameter into which the locking
tangs of the locking device may extend, and an innermost
chamber having a lesser diameter sized for snugly
receiving an end portion of a corresponding electrical
metallic tube or conduit adapted to be fitted into the
inlet end portion of the connector. The outermost chamber
and intermediate chamber at their inner end are defined
by shoulders and the inner end of the inner chamber being
defined by an inwardly extending shoulder which functions
as a stop to limit the distance the electrical metallic
tube can be inserted thereinto.
The locking device is formed of a spring steel
elongated blank which is rolled to define a split ring
having a leading edge and a trailing edge that are
inwardly bent relative to an intermediate planar portion
therebetween. The readily inwardly bent leading edge of
the locking device is provided with a series of
circumscribing locking or gripping tangs that are
inwardly and obliquely bent at approximately a 300 angle
which are inclined or obliquely angled toward the
intermediate chamber. The depending trailing edge of the
locking device includes a series of support tangs
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arranged to define the inner periphery of the inlet
opening of the connector body.
In one form of the invention, the intermediate
planar portion of the locking device is provided with one
or more holding tangs blanked or cut out of the plane of
the intermediate planar portion that are outwardly bent
and arranged to be received in a corresponding tang
opening formed in the connector body adjacent the inlet
opening in a manner to prohibit any pull-out of the
locking device from the connector body.
A resilient circular sealing ring or washer may be
optionally seated within the intermediate chamber
immediately forward of the leading edge of the locking
ring. The arrangement is such that to effect the
connection of an electrical metallic tube to the
connector body, one need only push one end of the
electrical metallic tube through the inlet opening and
through the locking or gripping tangs of the locking
device.
In another form of the invention, the locking device
may be secured within the connector body by a lock nut
threaded about the periphery of the inlet opening.
The connector or fitting embodying the invention may
also be in the form of a coupler for connecting two or
more electrical metallic tubes together.
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In another embodiment of the invention improved
sealing and continuity is obtained. Sealing is improved
by extending the intermediate chamber to prevent the
flexible gripping tangs from contacting the 0-ring seal
and providing a contact should on the flange for
contacting the electrical panel preventing excessive
deformation of the sealing washer by the locknut.
Continuity is improved between the connector body and the
electrical metallic tubing by providing a plurality of
internal radially increasing ribs that increase radially
while extending axially or longitudinally within the
connector body.
The various embodiments of the respective locking
devices include resilient holding tangs which also
function as an electric bond or ground.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is an exploded view of an electrical metallic
tube connector or fitting in which the component parts
are shown in section.
Fig. 2 is a section view of the connector or fitting
of Fig. 1 shown in the assembled position thereof.
Fig. 3 is an enlarged fragmentary portion of the
assembly of the connector or fitting of Figs. 1 and 2,
shown in section.
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Fig. 4 is a top plan view of the blank from which
the locking device is formed.
Fig. 4A is a perspective view of the locking ring
formed from the blank shown in Fig. 4.
Fig. 5 is a fragmentary sectional view of a modified
form of the invention.
Fig. 6 is a fragmentary sectional view of another
modified form of the invention.
Fig. 7 is an exploded view of another modified form
of the invention.
Fig. 8 is a sectional view of the embodiment of Fig.
7 showing the component parts in an assembled position.
Fig. 9 is a plan view of a modified blank from which
the locking device is formed.
Fig. 9A is a perspective view of the blank of Fig. 9
rolled to define a modified form of a locking device.
Fig. 10 is a perspective view of still another form
of the invention.
Fig. 11 is a fragmentary sectional side view taken
along line 11-11 of the embodiment of Fig. 10.
Fig. 12 is a perspective view of still another form
of the invention.
Fig. 13 is a sectional side view taken along line
13-13 in the embodiment of Fig. 12.
Fig. 14 is a perspective view of still another form
of the invention.
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Fig. 15 is a sectional side view of the embodiment
of Fig. 14.
Fig. 16 is an exploded view of another embodiment of
an electrical metallic tube connector or fitting in which
the component parts are shown in section.
Fig. 17 is a cross sectional view of the connector
or fitting of Fig. 16 shown assembled.
Fig. 18 is a cross section taken along line 18-18 in
Fig. 17.
Fig. 19 is an enlarged partial cross sectional view
illustrating the dimensional relationship between the
flexible gripping tangs and the 0-ring seal.
Fig. 20 is a cross sectional view of another
embodiment of an electrical metallic tube connector or
fitting.
Fig. 21 is a cross sectional view of another
embodiment of an electrical metallic tube coupler.
Fig. 22 is a cross sectional view of another
embodiment of an electrical metallic tube coupler.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, Figs. 1 to 4 illustrate
an electrical connector or fitting 20 for attaching a
conduit or an electrical metallic tube (EMT) 21 to an
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electric box or panel (not shown). Tube or conduit as
interchangeably used herein are to be accorded their
usual dictionary definition unless otherwise specified.
The connector or fitting 20 includes a connector body 22
having an inlet portion A and an outlet portion B.
Circumscribing the connector body exteriorly thereof is a
radially outwardly extending flange 23, which functions
as a stop to limit the distance the connector 20 may be
inserted through a knockout hole of an electric box or
panel, P.
As best shown in Fig. 1, the inlet portion A of the
connector body 22 is formed so as to define an enlarged
inlet opening circumscribing and defining an outer
chamber 25 having a diameter D1, terminating at the inner
end thereof by a shoulder 26. Concentrically disposed
adjacent the outer chamber 25 is an intermediate chamber
27 having a smaller diameter D2, the inner end being
defined by shoulder 28. Adjacent the intermediate
chamber 27 and concentric therewith is a smaller tube
chamber 29 having a diameter D3 sized to snugly receive an
end portion of an electrical metallic tube or conduit 21,
adapted to be fitted or connected to the connector body
22. The inner end of the tube chamber 29 is defined by a
shoulder 30 which forms a stop to limit the distance a
tube or conduit 21 may be inserted therein.
11
In accordance with this invention, the portion of
the connector body 22 defining the outermost chamber 25
is provided with one or more tang openings or apertures
31 circumferentially spaced therearound. The outlet
portion B of the connector body is provided with external
threading 32, which is adapted to be inserted through a
knockout hole of an electric box or panel P to which the
connector 20 may be secured by a locknut 33 or other
suitable means, e.g. a snap fit retainer ring of a type
disclosed in U.S. Patent 6,935,891.
According to this invention, a unidirectional
locking device 34 is provided so as to enable one to
attach an electrical metallic tube 21 thereto simply by
pushing an end portion of tube 21 into the inlet portion
of the connector body. This is attained by forming the
locking device 34 from a blank of spring steel 35. As
best seen in Fig. 3, the locking device 34 is preferably
formed of an elongated strip or blank of spring steel 35
or the like which is stamped and die cut or formed as
illustrated in Fig. 4, which is subsequently rolled or
formed in a configuration as best seen in Fig. 4A.
Referring to Fig. 4, the blank 35 includes a leading
portion 35A, a trailing portion 358 and an intermediate
portion 35C therebetween. As noted in Fig. 4, one end of
the blank 35 is provided with a tongue 35D which is
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adapted to mate with notch 35E when the blank is rolled
into its final form, as best noted in Fig. 1. Blanked
out or die cut out of the planar intermediate portion 35C
of the blank 35 are one or more holding tangs 35F which
are arranged to be cantileverly bent outwardly and having
the free end thereof arranged to engage or snap into a
corresponding tang opening 31 in the assembled position
thereof, as noted in Figs. 2 and 3.
The leading end portion 35A of the blank 35 is
provided or shaped to form a series of gripping tangs or
teeth 35G. The trailing end portion 358 is provided with
a series of spaced apart tube support tangs 35H, the
respective free ends of the tube support tangs 35H being
arcuately shaped so that in the final assembled form, the
tube support tangs 35H define the inlet opening to the
inlet end portion A.
To form the blank 35 into its final form, the
leading end portion 35A is inwardly bent along foldline F1
and the trailing end portion 35B is inwardly folded or
bent along foldline F2, and the blank rolled to form its
final circular configuration as shown in Fig. 4A. In
forming the locking device 34, the gripping tangs or
teeth 35E are inwardly and obliquely offset in the
direction of the outlet end portion B of the connector
body 22. The outer diameter of the locking device 34 is
sized so that the locking device 34 can be snugly
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received within the outer chamber 25 of the inlet end
portion A as noted in Figs. 2 and 3.
If it is desirable to render the connector
rainproof, a resilient sealing washer 37 may be
interposed in the intermediate chamber 27. As best seen
in Figs. 2 and 3, the resilient sealing washer 37 is
generally in the form of a truncated triangle in cross
section wherein the outer periphery of the sealing washer
defines the base portion of the general triangular cross
section, having a width substantially equal to the width
of the intermediate chamber 27. The short side of the
triangularly shaped cross section of the sealing washer
37 is disposed at approximately a 90 angle to the base
outer periphery and the hypotenuse of the triangular
cross section is disposed at an angle generally
complementing or at a slight angle relative to the
oblique angle of the gripping teeth or tangs 35H in the
relaxed state as best seen in Fig. 2. The outer diameter
of the sealing washer is sized so as to be snugly
received within the intermediate chamber 27. The inner
diameter of the washer 37 is slightly less than the outer
diameter of the tube 21, adapted to be fitted to the
described connector so that when the end of the tube 21
is inserted into the inlet portion A and through the
locking device and associated sealing washer 37, the apex
portion of the sealing washer will compress so as to
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impart a sealing contact pressure on the tube 21 so as to
effectively prohibit any moisture or rain water to pass
by the sealing washer 37 and toward the outlet end
portion B extending into an electric box or panel. A
suitable sealing washer material may be neoprene, nitrile
or other suitable resilient like material. It will be
understood that the connector body 22 may be suitably
molded or cast out of zinc, steel or other suitable metal
or alloy.
In assembly, the resilient sealing washer 37 is
positioned in the intermediate chamber 27 of the inlet
end portion A so that the short side of the resilient
sealing washer 37 is in abutment with shoulder 28. The
locking device 34 is inserted into the outer chamber 25
of the inlet end portion oriented so that the holding
tangs 35F are in line with the tang openings 31. The
arrangement is such that the split locking device may be
compressed so as to close the gap between the opposed
ends thereof so that the locking device 34 may be readily
inserted or press-fitted into the outer chamber 25 until
the leading edge abuts up against shoulder 26. Upon
insertion of the locking device into chamber 25, the
holding tangs 35F will initially be forced inwardly
toward the intermediate planar surface 35C and then will
inherently spring outwardly as the holding tangs 35F are
brought into alignment with its corresponding tang
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opening 31 so as to secure the locking device 34 within
chamber 25. With the locking device secured within
chamber 25, the gripping tang will be obliquely directed
toward the hypotenuse of the sealing washer 37 in a
relaxed state so as to define a slight angle
therebeLween, as noted in Fig. 2.
With the sealing washer 37 and locking device 34 so
disposed and retained within the inlet end portion 13 of
the connector body 22, one need only to push an
electrical metallic tube 21 pass the gripping tangs 35B
of the locking device 34 and the sealing washer until the
end of the tube 21 engages the stop shoulder 30. As the
tube 21 is pushed through the ring of locking tangs, the
tangs are slightly displaced to close the slight angle
normally disposed between the hypotenuse of the sealing
washer and gripping tangs (as best seen in phantom in
Fig. 3). As a result, the gripping tangs effect an
inherent gripping force on the tube so as to resist any
opposing or pulling force that may be applied onto the
tube in an effort to effect separation of the tube from
the connector body 22. With the tube 21 so connected,
the arrangement is such that the tube 21 is also firmly
supported both at its inner end by the snug fitting
relationship with support chamber 29 and by the support
tangs 35H of the locking device 34 which are spaced apart
from the support chamber. Accordingly, the two point
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support for the tube serve to resist any unwanted bending
stresses to which the tube may be subjected.
To attach the connector body to an electric box or
panel, the threaded outlet end portion B is sized so as
to be readily insertable through any standard knockout
opening. The connector body is secured to the electric
box or panel by the lock nut 33 in the usual manner. If
desired, a resilient sealing washer 36 may be interposed
between the lock nut 33 and the wall of an electric box
or panel P to prohibit any moisture or rain from entering
through the knockout hole. It will be understood that
the outlet end portion B may be formed or fitted with
snap fit retaining ring as hereinbefore noted, by which
the connector body may be secured to an electric box or
panel.
Fig. 5 illustrates a slightly modified embodiment of
the invention. In this form of the invention, the
connector 40 includes a connector body 41 similar to that
hereinbefore described. The embodiment of Fig. 5 differs
from the embodiment of Figs. 1 to 4 in that the outer
chamber is devoid of any tang openings 31 as previously
described. Also, the locking device 43 differs from the
locking device 34 as described and shown in Figs. 4 and
4A. The locking device 43 is similar to that illustrated
in Fig. 9A, as will be hereinafter described.
Essentially, the locking device 43 of the embodiment of
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Fig. 5 is devoid of the tube support tangs 35H,
previously described. in lieu thereof, a backup washer
44 having a central opening 44A sized to snugly receive
the electrical metallic tube 21 functions as a tube
support. Disposed within the intermediate chamber is the
resilient sealing washer 42 which is similar to that
previously described. To retain the backup washer 44,
the locking device 43 and the resilient sealing washer 42
in their respective position, the connector body is
provided with an inturned lip 46 which is radially and
inwardly bent or swaged or deformed to secure the
respective components permanently in place. In this form
of the invention, the tangs 47 formed about the
intermediate planar portion of the locking device are
maintained in the compressed state when the locking
device 43 is disposed with its outer chamber. Due to the
inherent resiliency of the tangs 47 and the tendency of
tangs 47 to assume its outwardly bent relaxed state, a
positive electric grounding effect is assured. In this
form of the invention, the sealing washer 42, the locking
device 43 and the backup washer 44 are permanently
secured within the connector body. To attach a metal
tube 21 to the connector body, one need only to push an
end portion of a tube 21 through the inlet opening 44A of
the washer 44 and pass the gripping tangs 48 of the
locking device 43.
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Fig. 6 illustrates another slightly modified
embodiment of the invention. In this embodiment, the
connector body 50 has been modified to the extent that
the inlet end portion 50A has been slightly modified to
accommodate the resilient sealing washer 51 between the
backup washer 52 and the locking device 53. Like in Fig.
5, the connector body 50 adjacent the inlet opening is
provided with a radially inwardly formed lip or flange 54
which functions to lock the locking device 53 and the
resilient sealing washer 51 in place within the inlet end
portion 50A. As hereinbefore described to secure a tube
21 to the connector body 50, one need only insert the end
portion of a tube 21 into the inlet end portion 50A until
the end of the tube engages the innermost stop, as
hereinbefore described. In all other respects, the
structure and function is similar to that hereinbefore
described.
Figs. 7 to 9 illustrate a further embodiment of the
invention. In this form of the invention, the connector
60 includes a connector body 61 similar to that
hereinbefore described with respect to Fig. 1, except
that the inlet end portion 60A is provided with an
externally threaded portion 62 circumscribing the inlet
opening 63. Essentially, the inlet end portion 60A has
an outer chamber 64 and intermediate chamber 65 and tube
receiving chamber 66 as previously described.
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In this form of the invention, the locking device 67
is also slightly modified. Referring to Fig. 9, the
locking device 67 is formed out of an elongated blank 68
of suitable spring steel metal having opposed end
portions, one end having a projecting tongue 68A and a
notch 68B formed in the other end of the blank. The
blank also has a leading edge portion 68C, a trailing
edge 68D and a planar intermediate portion 68E
therebetween. The blank 68 also includes a series of
tangs 69 that are die cut or blanked out of the plane of
the intermediate portion 68E, the free end of tangs 69
being outwardly bent relative to the plane of the
intermediate portion from which the tangs 69 are formed.
To form the locking device 67, the blank 68 so formed is
rolled into a circular ring wherein the projecting tongue
68A is fitted into notch 68B of the other end. The
leading edge portion of the blank 68 is rolled or
progressively bent radially inwardly along foldline F3 to
form a substantially 90' angle at the corner thereof as
best seen in Fig. 8. As hereinbefore described, a series
of gripping teeth or tangs 70 along the leading edge of
the locking device 67 are normally obliquely bent outward
toward the tube holding chamber 66. Securing the locking
device 67 and the sealing ring 71 within the inlet end
portion 60A of the connector body 61 is a back nut 72,
which is provided with internal threading 72A by which it
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can be threaded onto the external threads 62 on the end
of the connector body 61. The back nut 72 is provided
with a center opening 72B having a diameter sized to
accommodate a tube 21 associated therewith. To lock and
secure a tube 21 to the connector 60, one simply needs to
push the tube 21 through the back nut opening 72B, the
locking device 67, the resilient sealing washer 71 and
into the tube chamber 66 until the end of the tube abuts
against the stop shoulder 66A.
In this form of the invention, it is to be noted
that in positioning the locking device 67 into the inlet
chamber portion 64, the arrangement is such that the
tangs 69 of the locking device 67 are compressed inwardly
so that when the locking device is fully seated within
chamber 64, the inherent resiliency of the tangs 69 tend
to exert an outwardly biasing force against the inner
surface of chamber 64. The inherent biasing force
imparted by the tangs 69 onto the internal surface of the
chamber 64 ensures that the tangs 69 are maintained in
positive contact with the internal surface of the
connector body 61 to provide a positive electrical
grounding effect.
In all other respects, connector 60 is structurally
and functionally similar to the embodiment described with
respect to the embodiment of Figs. 1 to 4.
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Figs. 10 and 11 are directed to another modified
form of the invention. This embodiment is directed to a
connector 80 which is similar to the connector 60 as
shown in Figs. 7 to 9, except that the connector body 81
is provided with internal threads 82 circumscribing the
inlet opening 83 to the outer chamber 84. The locking
device 85 and the resilient sealing washer 86 are similar
to those described with respect to Figs. 7 to 9. In the
embodiment of Figs. 10 and 11, the locking device 85 and
sealing washer 86 are secured within the inlet end
portion of the connector body 81 by a back nut 87 having
a short externally threaded stem 87A and a radially
outwardly extending flange 87B whereby the internal
thread stem 87A engages the inlet threads 82 of the
connector body 81. In all other respects, the connector
80 is similar to connector 60 of Figs. 7 to 9.
Figs. 12 to 13 illustrate a further application of
the invention described herein. As shown, the embodiment
of Figs. 12 and 13 is directed to a connector in the form
of a coupler 90 for connecting at least two electrical
metallic tubes together. Coupler 90 includes a metal
casting formed of a suitable metal or alloy as
hereinbefore noted, which has an integral cylindrical
center portion 91 terminating in opposed outwardly
flaring end portions 91A, 91B. In the illustrated
embodiment, the respective end portions 91A, 91B are
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identical mirror images of the other. However, it will be
understood that the end portion need not be of the same
size and that the dimensions thereof may be varied to
accommodate varying size tubes 21.
In the illustrated embodiment of Figs. 12 and 13,
each end portion 91A, 91B are formed with an outer
chamber 92A, 92B, an intermediate chamber 93A, 93B, and a
tube support chamber 94A, 94B similar to that described
with respect to the embodiment of Figs. 1 to 4.
Intermediate the cylindrical portion 91 of the coupler,
there is provided an internal rib or flange 95 which
functions as a stop for the tube end. Circumferentially
spaced about the respective end portions 91A, 92B are one
or more holes or apertures 96.
The locking devices 97A, 973 and resilient sealing
washers 98A, 983 are similar in structure and function as
hereinbefore described with respect to Figs. 1 to 4, and
need not be repeated.
In this form of the invention, the resilient sealing
washers 98A, 98B and locking devices 97A, 97B are
positioned and secured within their respective chambers
similar to that described in Figs. 1 to 4. Thus, all of
the features and advantages noted with respect to the
embodiment of Figs. 1 to 4 are also achieved when
employed in a coupler type fitting of Figs. 12 and 13.
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Figs. 14 and 15 are directed to another embodiment
of the invention. In this form, the invention is
directed to a modified coupler 100 which is similar in
virtually all respects to that described with respect to
Figs. 12 and 13, except that the opposed enlarged inlet
end portions 100A, 100B are provided with external
threads 101 and 102 respectively for receiving a backup
nut 103, 104, similar to that hereinbefore described.
Also, in this form of the invention, the coupling body
105 does not require any tang openings 96, as described
with respect to the embodiment of Figs. 12 and 13.
The resilient sealing ring 106A, 106B and locking
device 107A, 107B are similar to the respective sealing
ring and locking device as described with respect to the
embodiment of Figs. 7 and 8. In all other respects, the
embodiment of Figs. 13 and 14 are structurally and
functionally similar to that disclosed and described with
respect to the embodiment of Figs. 7 to 9.
From the foregoing disclosure, it will be apparent
that the push-on type of connectors herein are described
as being primarily useful for connecting an electrical
metallic tube or EMT. However, the described fittings
may also be utilized as a connector for non electric
tubes, e.g. plastic tubes and the like. As described
herein, the novelty resides primarily in the resilient
sealing washer having a generally truncated triangular
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cross sectional shape and a locking device which is
rendered reusable, and which is formed to positively
provide a unidirectional gripping force on the associated
tube or conduit, and in one form a support for the
associated tube to resist any bending forces imparted on
the tube at the point of connection, and to provide an
electrical bonding path when used with metallic tubing.
As in certain of the described embodiments, the
locking device is provided with holding tangs co-
operationally associated with corresponding tang openings
formed in the inlet end portion of the connector body for
positively securing the locking device within the inlet
end portion, whereby the use of a backup nut may be
eliminated to further simplify the structure of the
described embodiments. In addition to the holding tang
of the locking device, in one form of the invention
described herein may also function as a very positive
electrical grounding means.
In their respective entirety, the connector
embodiments described herein greatly simplify the
manufacturing and assembly of such connectors, reduces
the costs thereof, and provides an arrangement whereby a
tube or conduit associated therewith can be simply
attached thereto by merely pushing one end of the conduit
or tube through the inlet opening and through the
unidirectional locking device that will resist any
CA 02751965 2011-09-12
opposing force or pulling force which may be imparted on
the tube to prohibit any separation. The described
embodiments utilizing a backup nut, achieve a further
advantage in that simple removal of the backup nut
provides a means for readily removing the tube or conduit
in the event disassembly is required without effecting or
imparting any damage to the component parts, thereby
rendering the components reusable.
Figs. 16-22 illustrate additional embodiments of the
present invention that provide improved continuity and
sealing. Figs. 16-19 illustrate an embodiment that is
similar to the embodiment illustrated in Fig. 1, however,
the embodiment illustrated in Figs. 16-19 has improved
continuity and sealing. The improved continuity provides
a reduced voltage drop across the electrical fitting or
connector.
In Fig 16, the connector body 22 has a plurality of
internal longitudinal radially increasing ribs 222. There
are preferably three ribs 222 separated by approximately
one-hundred and twenty degrees. The ribs 222 increase
radially progressing longitudinally from shoulder 28 to
the shoulder 30. Accordingly, the ribs 222 effectively
reduce the diameter distance D3 of the tube chamber 29
progressing longitudinally from shoulder 28 to shoulder
30. Additionally, in this embodiment an 0-ring 237 is
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CA 02751965 2011-09-12
used and positioned in the intermediate chamber 27. The
0-ring 237 is positioned so as not to contact the
gripping tangs 35G when the unidirectional locking device
34 is placed within the outer chamber 25 and an
electrical metallic tube or EMT is placed within the
connector or fitting 20. This prevents deformation of the
0-ring 237 and reduces the possibility of leaks.
Fig. 17 illustrates the connector or fitting 20
illustrated in Fig. 16 in an assembled state and with an
electrical metallic tube or EMT 21 placed within the
connector or fitting 20. The internal longitudinal
radially increasing ribs 222 placed within the tube
chamber 29 of the connector body 22 contact the leading
edge of the tube 21. The ribs 222 assure a good
electrical contact between the tube 21 and the connector
body 22. The ribs 222 extend into the tube chamber 29 by
an increasing radial dimension from the shoulder 28 to
the shoulder 30. The maximum increase in radial dimension
of the ribs 222 should be approximately the expected
variance in the dimension of the tube 21. Generally,
electrical metallic tubes or EMTs will have dimensional
tolerances resulting in the diameter being within a
limited range. For a nominal one-half inch tube, the
outside diameter dimension may vary 0.10 inches.
Therefore, for a nominal one-half inch tube, the ribs 222
preferably extend radially into the tube chamber 29 a
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CA 02751965 2011-09-12
maximum of 0.10 inches. Accordingly, as the tube 21 is
inserted into the tube chamber 29 the leading edge of the
tube 21 contacts the ribs 222 providing a secure fit. The
leading edge of the tube 21 will also shave a small
portion of the ribs surface resulting in a clean
electrical contact improving continuity. The connector
body 22 is preferably made of a die cast zinc alloy and
is typically softer than the material of tube 21. This
causes ribs 222 to be shaved or cut as the tube 21 is
inserted resulting in a clean good electrical and
mechanical contact being provided. In experimental
connectors or fittings, fittings with the ribs 222
resulted in a substantially reduced voltage drop across
the fitting. Fittings with the ribs 222 had an eighty
percent reduction in voltage drop across the fitting
using a short circuit current of 30 amps DC as compared
to fittings without the ribs 222. While the primary
function of the ribs 222 is to improve electrical
continuity and decrease a voltage drop across the
fitting, the ribs 222 may also provide a contact point
holding an end of the tube 21 restricting movement which
may improve sealing.
Fig. 17 also illustrates the improved sealing with a
connection to the electrical box or panel P. As
illustrated in Fig. 17, flange 23 has a flange shoulder
23A that acts as a stop for the sealing washer 36.
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CA 02751965 2011-09-12
Sealing washer 36 is made of a compressible elastomeric
or rubber material. The locknut 33 forces the panel P
against the sealing washer 36, and the sealing washer 36
is forced against the flange shoulder 23A. A contact
shoulder 224 is formed on and extends from the flange 23.
The contact shoulder 224 has a diameter greater than an
opening in the panel P so that when the locknut 33 is
forces against the panel P, the panel P will contact the
contact shoulder 224 formed on and extending from the
flange 23. The distance between the flange shoulder 23A
and the contact shoulder 224 is set so that the sealing
washer 36 is prevented from being excessively compressed,
which could result in improper or faulty sealing. The
sealing washer 36 is prevented from being excessively
compressed and deformed by the panel P contacting the
contact shoulder 224. This improves the ability of the
fitting to seal out moisture or be rain tight.
Additionally, the contact shoulder 224 permits the
locknut 33 to be tightened against the panel P with
additional torque due to the bottoming out or contact
with the contact shoulder 224. This additional torque
results in a higher metal to metal or conductor to
conductor clamping or contact force which lowers contact
resistance and improves overall electrical continuity.
Fig. 18 is a cross section taken along lines 18-18
in Fig. 17 and illustrates ribs 222 contacting the tube
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CA 02751965 2011-09-12
21. The ribs 222 also aid in centering the tube 21 within
the connector body 22.
Fig. 19 is a partial cross section illustrating the
improved seal between the 0-ring 237 and the tube 21 due
to the dimensions of the intermediate chamber 27 and the
flex of the gripping tangs 35G. The 0-ring 237 is placed
in the intermediate chamber 27 and has a longitudinal or
axial dimension Li equal to the diameter of the 0-ring
237. The unidirectional locking device 34 is positioned
in the fitting so that the travel distance L3 of the
gripping tangs 35G always results in a gap distance L2
between the 0-ring 237 and gripping tangs 35G. That is,
the intermediate chamber 27 longitudinal or axial
dimension is greater than the combined longitudinal or
axial travel distance L3 of the plurality of griping tangs
and the sealing ring longitudinal or axial dimension 1,1.
Therefore, a gap distance L2 is maintained between the 0-
ring 237 and the gripping tangs 35G. This prevents the
gripping tangs 35G from contacting the 0-ring 237 and
possibly compromising the sealing contact surface between
the 0-ring 237 and the tube 21.
Fig. 20 is another embodiment of a connector or
fitting 60 that uses a back nut 72 to retain the
unidirectional locking device 67 within the chamber
portion 64. This embodiment also includes the improved
continuity and sealing features illustrated in Figs. 16-
CA 02751965 2011-09-12
19 and is similar to the embodiment illustrated in Fig.
7. In this embodiment the connector body 61 has a
plurality of internal longitudinal radially increasing
ribs 361. Also similar to the embodiment illustrated in
Fig. 16, an 0-ring 371 is placed within the intermediate
chamber 65 of the connector body 61. The longitudinal or
axial dimensions of the intermediate chamber 65, the 0-
ring 371, and the gripping teeth or tangs 70 are such
that when the gripping teeth or tangs 70 flex to hold a
tube, not illustrated, the gripping teeth or tangs 70 do
not contact the 0-ring 371. Also flange 323 has a contact
shoulder 324 that contacts the panel P preventing the
panel P from excessively deforming the sealing washer 36.
Fig. 21 illustrates a coupler for coupling two tubes
together. The coupler illustrated in Fig. 21 is similar
to the coupler illustrated in Figs. 12 and 13. However,
the embodiment illustrated in Fig. 21 provides improved
sealing and continuity. In this embodiment the coupler
body 90 has a plurality of internal longitudinal radially
increasing ribs 490 and 492. 0-ring seals 498A and 498B
are placed within respective intermediate chambers 93A
and 93B of the coupler body 90. The longitudinal or axial
dimensions of the intermediate chambers 93A and 93B, the
0-rings 498A and 498B, and the travel distance of
gripping teeth or tangs 35G are such that when the
gripping teeth or tangs 35G flex to hold a tube, not
31
CA 02751965 2011-09-12
illustrated, the gripping teeth or tangs 35G do not
contact the respective 0-rings 498A and 498B.
Fig. 22 illustrates a coupler for coupling two tubes
together. The coupler illustrated in Fig. 22 is similar
to the coupler illustrated in Figs. 14 and 15. However,
the embodiment illustrated in Fig. 22 provides improved
sealing and continuity. In this embodiment the coupler
body 100 has a plurality of internal longitudinal
radially increasing ribs 505 and 506. 0-ring seals 506A
and 506B are placed within respective intermediate
chambers of the coupler body 100. The longitudinal or
axial dimensions of the intermediate chambers, the 0-
rings 505 and 506, and the travel distance of gripping
teeth or tangs 70 are such that when the gripping teeth
or tangs 70 flex to hold a tube, not illustrated, the
gripping teeth or tangs 70 do not contact the respective
0-rings 506A and 506B.
The embodiments illustrated in the present
invention, particularly as illustrated in Figs. 16-22,
provides an electrical fitting that has superior sealing
and continuity with a reduced voltage drop. This improves
the safety of the electrical fitting as well as
performance in moist or wet locations.
While the present invention has been described with
respect to several embodiments, it will be understood
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CA 02751965 2011-09-12
that various modifications may be made without departing
from the spirit or scope of the invention.
33
