Note: Descriptions are shown in the official language in which they were submitted.
CA 02363636 2001-11-22
FIELD OF THE INVENTION
This invention relates generally to wire connectors, and more specifically, to
a twist-on wire
connector having a lubricant thereon to reduce the torque required to set the
electrical wires
in the wire connector and at the same ensure that the electrical wires are
securely engaged so
that normal thermal expansion and contraction or shock and vibration
conditions will not
cause the wires to loosen in the connector.
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority form provisional application titled LOW
TORQUE
TWIST-ON WIRE CONNECTOR U.S. Serial Number 60/251,111 filed December 5,
2000.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
None
REFERENCE TO A MICROFICHE APPENDIX
None
BACKGROUND OF THE INVENTION
The concept of wire connectors for connecting the junction of two or more
wires together
by twisting a cap on the wires is old in the art. Wire connectors are well
known in the art
and generally comprise an outer housing with a tapered threaded interior to
permit a user to
insert wires into the tapered opening. To use a wire connector, the user
inserts the twisted
ends of electrical wires into a cavity on the inside of the wire connector.
The user then holds
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the wire in one hand and with the other hand twists the wire connector. The
twisting action
pulls the junction ends of the wires into a low resistance electrical contact.
If the connector is located in a wet location it is necessary to place a
waterproof sealant
around the connector. In order to prevent water or moisture from entering the
connector and
forming an oxidation layer over the ends of the wire the user inserts the wire
connector and
the wire into some type of a waterproof potting compound. The compound may be
either a
non hardening or a hardening compound. In either case the compound creates a
waterproof
capsule over the wire connector and the junction ends of the electrical wires.
The prior art process is time consuming because it involves two separate steps
as well as the
nuisance of having separate potting compounds and containers to hold the
potting
compound. A second generation improved twist-on wire connector wherein the
wires can be
encapsulated and sealed in a twist on wire connector to prevent water or
moisture from
entering the connector is shown in my U.S. patents 5,113,037; 5,023,402 and
5,151,239.
The second generation twist-on wire connectors permits the user in one
continuous action to
simultaneously form the junction ends of wire leads into a low resistance
electrical
connection that is surrounded by a waterproof sealant to form a waterproof
covering around
the junction ends of the wire leads.
Under certain dynamic conditions, such as vibration and shock, or large
temperature
changes the wires in the twist-on wire connector can become loosened and thus
lower the
integrity of the connection between the wires in the twist on wire connectors
by either
increasing the electrical resistance or decreasing the contact area or both. I
call the present
invention a third generation electrical twist-on wire connector wherein the
integrity of the
low resistance electrical connection of the twist-on wire connector is
actually enhanced by
placing a small amount of self-adhering lubricant in the twist-on wire
connector. Generally,
CA 02363636 2001-11-22
to enhance the electrical conductive between connector and wire one needs only
a small
amount of self-adhering lubricant to provide an enhanced low resistance
electrical
connection. In the present invention, it has been found that when a small
amount of a self-
adhering lubricant has been incorporated into the wire connector it results in
an enhanced
low resistance electrical connection.
In order to ensure that twist-on wire connectors remain in a low-resistance
electrical
connection when subject to environmental conditions of shock and vibration one
prior art
method is to encapsulate the twist-on wire connectors in a solid resin. In
other methods
tools may be used to apply extra torque to the wires to cause further
engagement of the
threads of the wire connector with the electrical wires. In the present method
one need not
resort to encapsulation with a solidified resin and one need not resort to
using tools to
enhance the torque since it has been found that even though a lubricant is
used the
suspected detrimental effects of use of a lubricant film between the wire and
the wire
IS connector is overcome by the greater physical engagement between the wires
which can be
obtained by use of the lubricant. That is, the lubricant allows one to reduce
the torque that
may be required to make a secure connection in a twist-on wire connector. As a
result one
can hand tighten a twist-on wire connector containing a small amount of self-
adhering
lubricant and provide for greater electrical contact between the wires which
results in
retention of the low-resistance electrical connection even in the presence of
forces such as
vibration and shock.
SUMMARY OF THE INVENTION
Briefly, the present invention is an improved twist-on wire connector that
permits the user to
form the junction ends of wire leads into a low resistance electrical
connection with the
twist-on wire connector including a self adhering lubricant located along a
portion of the
interior of the twist-on wire connector. The wires are drawn into the housing
by a spiral
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CA 02363636 2001-11-22
thread through the twisting action of the wires with respect to housing. As
the wires are
drawn into the spiral thread, the frictianl resistance to the rotation of the
wires increases until
the wires can no longer be hand twisted into the wire connector. Once the
wires are drawn
into contact with the lubricant the torque resistance, which is a result of
frictional resistance
S between the wires and the spiral thread, decreases while the radial
compressive forces
between the wires and the spiral thread are substantially unaffected.
Consequently, the rate
of torsonial resistance decreases allowing the wires to be brought into
further electrical
contact along a greater length through only hand tightening while at the same
time the
radially compressive forces on the wires are greater thus ensuring a low
resistance electrical
contact that remains stable over an extending period of time. Because only a
small amount
of self-adhering lubricant is needed within the wire connector to provide an
enhanced low-
resistance electrical connection problems of the self-adhering lubricant
accidentally coming
into contact with the exterior housing of other twist-on wire connectors is
minimized even if
caps are not used on the twist-on wire connectors.
IS
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view showing a twist-on wire connector free of any
lubricant;
FIG. 2 is a cross-sectional view showing a twist-on wire connector with a
lubricant located
at the end of the spiral thread;
FIG. 3 is a cross-sectional view showing a twist-on wire connector with a
lubricant
extending axially along the spiral thread;
FIG. 4 is a cross-sectional view showing a twist-on wire connector with a
lubricant film
extending around the spiral thread of the twist-on wire connector;
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Fig. 5 is a cross-sectional view showing a twist-on wire connector with a
lubricant located at
the end of the spiral thread and a pair of wires engaging the spiral thread
which is free of
lubrication;
Fig. 6 is a cross-sectional view showing the twist on wire connector of Fig. 5
with the wires
engaging the lubricant on the spiral threads;
Fig. 7 is a diagram illustrating the torsional resistance as a function of
wire penetration both
with and without the use of a lubricant; and
Fig. 8 is a cross-sectional view showing the twist on wire connector of Fig. 5
with a cover
on the end of the wire connector.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, reference numeral 10 generally identifies a conventional
twist-on wire
connector. Wire connector 10 includes an electrical insulating housing 11
having an open
end 12 and a closed end 13 with the diameter of open end 12 being larger than
the diameter
of closed end 13. A spiral thread 16 extends axially inwardly in housing 11.
The diameter
of spiral thread 16 proximate open end 12 of housing 11 is larger than the
diameter of spiral
thread 16 proximate closed end 13 of housing 11 so that wires are squeezed
into tighter
contact with each other as the wires are twisted into the spiral thread. While
the embodiment
shows that the spiral thread is a metal spring it is envisioned that the
spiral thread could be
integrally formed within the housing of the twist-on wire connector.
Figure 2 shows an embodiment of the present invention having a self-adhering
lubricant IS
positioned at the closed end 13 of connector 10. The self-adhering lubricant
15 extends an
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axial distance x1 along the spiral threads. In contrast, the spiral threads
designated by ~ are
free of self-adhering lubricant.
Figure 3 shows a further embodiment of the present invention having a self-
adhering
lubricant strip 18 positioned axially along the spiral thread 16. The amount
of self-adhering
lubricant is sufficient to provide lubrication between the contact surfaces of
the wires and
the spiral thread but insufficient to fill the spiral thread and encapsulate
the wires.
Figure 4 shows a further embodiment of the present invention having a self-
adhering
lubricant film extending axially along the spiral thread 16. The amount of
self-adhering
lubricant is sufficient to provide a thin lubrication film between the contact
surfaces of the
wires and the spiral thread but insufficient to fill the spiral thread and
encapsulate the wires.
That is, a preferred method of placing the lubricant in the wire connector is
to apply a film
of lubricant to a portion of the threads of the wire connector.
Figure 5 shows the twist-on wire connector 10 with self-adhering lubricant 15
positioned at
the closed end of the wire connector and a pair of electrical wires 20, 21
engaging the outer
portion of the spiral thread 16, which is free of self adhering lubricant.
This illustrates the
first step in the engagement of the wires with the twist on wire connectors.
That is, a rotation
of the twist-on wire connector 10 with respect to wires 20 and 21 produces
contact
engagement between the two causing the wires to be drawn deeper into the
cavity within the
twist-on wire connector. In the embodiment shown the engagement between the
wires 20, 21
and the spiral thread 16 is direct without the presence of any lubricant. As
the wires are
drawn into the spiral thread the torsonial resistance to twisting the wires
increases.
Figure 6 illustrates the twist-on wire connector of Figure 5 once the wires 20
and 21 engage
the self-adhering lubricant 15. Once the wires engage the self adhering
lubricant 15 further
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twisting action cause the lubricant 15 to form a film between the spiral
threads 16 and the
wires 15 thereby decreasing the torsional frictional resistance to twisting
the wires while
maintaining the radially compressive forces on the electrical wires. Figure 6
shows the twist-
on wire connector 10 with an open end; however, if desired a cap such as shown
in U.S.
patent 5,113,037 could be placed on the end.
A number of lubricants are usable in the present invention, suitable
lubricants are of the type
that will remain insitu within the wire connector during normal handling. As
the lubricant is
not required to form a filling or enclosure that encapsulates the wires a wide
range of
lubricants from liquids to solids can be used. For example, liquid lubricants
that will adhere
to a surface and form a film thereon are suitable for use with the present
invention since the
lubricant need only reduce the torsional frictional resistance between the
wires and the spiral
thread. In certain applications, the lubricant may be electrically
conductive;however, a non-
electrically conductive lubricant can also be used. It is envisioned that
themorsetting resins
could also be used provided that the thermosetting resins have lubricating
qualities and can
adhere to the spiral thread when in a liquid state. As can be seen from the
drawings only a
small amount of lubricant is needed to obtain the benefit of the present
invention. That is,
only sufficient lubricant is required to form a reduced frictional resistance
between the wires
and the spiral thread.
A reference to Figure 7 provides a quantitative guide to the torsonial force
in engaging a
twist on wire connector with a set of wires. The torsonial force is located
along the vertical
axis and the penetration distance is located along the horizontal axis. The
solid line, which is
identified by reference numeral 25, shows the general increase of torsonial
force as a
function of penetration of the wires into the connector when there is no
lubricant present.
The dashed line 27 illustrates the torsonial force as the twist-on wire
connector is twisted on
to the wires when lubricant is present on a portion of the spiral thread. When
the lubricant is
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CA 02363636 2001-11-22
present on only a portion of the spiral thread he torsional force increases up
to the distance
x~ which indicates the point where the wires engage the self adhering
lubricant. Once the
wires engage the self adhering lubricant the rate of increase of torsional
resistance as
indicated by dashed line 27 increases at a lesser rate allowing a user to
bring the wires
deeper into the wire connector while using less force. Since the deeper the
wires are in the
twist-on electrical connector the greater the radially compressive forces
between the spiral
threads and the wires the better the electrical contact between the wires and
the spiral thread.
Thus part of the present invention comprises a method of making a two-stage
twist-on wire
connector which comprises the steps of forming a housing 11 having an exterior
surface
1 la for hand grasping by a user. Placing a spiral thread 16 on the interior
of the housing 11
with the spiral thread having an open end and a closed end with a diameter of
the open end
of the spiral thread larger than the diameter of the closed end with the
spiral thread
diametrically converging in an axial direction toward the closed end. Next one
inserts a self
adhering lubricant into the closed end of the spiral thread with the lubricant
partially
covering the spiral thread proximate the closed end thereby leaving a further
portion of the
spiral thread proximate the open end free of lubricant. Normally, a plurality
of wires which
require N turns of the twist-on wire connector to fully engage the plurality
of wires with the
spiral thread which is free of lubricant and M additional turns of the twist-
on wire connector
to fully engage the plurality of wires with the spiral thread carrying the
lubricant. The spiral
thread with the lubricant thereon reduces the requirement for increased torque
on the twist-
on wire connector that might normally require the use of a separate tool to
turn the twist-on
connector to fully engaged postion with the plurality of wires. To complete
the connection
one inserts a plurality of wire ends to be spliced into the open end of the
spiral thread and
twists the spiral thread with respect to the plurality of wires 20, 21 to draw
the plurality of
wire ends proximate the closed end of the spiral thread and into grater radial
compression to
thereby improve the continuity and long term stability of the electrical
connection.
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With the present invention it will be appreciated that with only a strip or a
small amount of
lubricant in the wire connector is sufficient to provide reduced torsional
friction since the
twisting action of wires with respect to the spiral thread apples the
lubricant to the surfaces
by dragging or pulling the lubricant along as wires are rotated with respect
to the spiral
thread of the connectors. Consequently, only a small amount of lubricant need
be used in
the spiral thread and the placement of the lubricant on a portion of the
spiral thread surface
which contacts a rotating wire will automatically become lubricated by the
action of
engaging the wire connector with the wires. The lubricants in use with the
present invention
can be dielectric or non-dielectric lubricants as well as either electrical
insulating or non-
electrical insulating sealants.
While the low amount of lubricant used with the present invention makes it
ideally suitable
for use without a cap the embodiment shown in Figure 8 includes a cap 30
having a set of
radially projecting flexible member that part to allow penetration of the
wires into the cavity
of the electrical twist-on wire connector. An example of a cap is shown and my
patent
5,113,037 which is hereby incorporated by reference.
As an alternative method the spiral thread can be precoated or plated with a
metal that
functions as a lubricant. Such preplateing is not limited to metals, for
example, materials
such as polytetrafluoroethylene (Teflon) could be placed on the spiral threads
to reduce the
frictional requirements. A result of the low resistance connection of the
present invention is
that the connection between wires remains cooler and hence more efficient.
While the preferred method is to apply a film of lubricant to the wire
connector it is
envisioned that a method of the present invention could involve applying the
film of
lubricant to a wire to be brought into electrical contact by the threads of
the wire connector.
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Thus the present invention is a twist-on wire connector for maintaining the
integrity of an
electrical connection therein including a housing for grasping in a user's
hand, with the
housing having an open end and a closed end, a spiral thread located within
the housing, the
spiral thread extending inwardly in the housing with the spiral thread having
a larger
diameter proximate the open end of the housing and a smaller diameter portion
proximate
the closed end of the housing. the spiral thread having a portion free of a
lubricant and a
further portion carrying a film of lubricant with the film of lubricant carned
by the spiral
tread insufficient to encapsulate and waterproof a plurality of electrical
wires located therein.
While two electrical wires are shown the present invention is suitable for use
with more or
less wires. In addition, the present invention and method is not only suitable
for use with
conventional electrical voltages it is also suitable low voltage applications
included in
applications such as speaker wires or the like.
IS In another embodiment the twist-on wire connector for maintaining the
integrity of an
electrical connection therein includes a housing for grasping in a user's
hand; a spiral thread
located within the housing with the spiral thread extending inwardly in the
housing with the
spiral thread having a larger diameter proximate an open end of the housing
and a smaller
diameter portion proximate a closed end of the housing. A film of lubricant or
a small
amount of lubricant is carned by the spiral tread with the film of lubricant
insufficient to
encapsulate and waterproof a plurality of electrical wires located therein but
sufficient to
reduce frictional resistant between a contact area located between the
plurality of wires and
the spiral thread to thereby provide for an enhanced contact area without
enhancing an
amount of torque applied to the plurality of wires.
A method of the present invention includes the making a low resistance
electrical resistance
connection to withstand adverse environmental conditions due to changes in
temperature by
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placing an electrical wire having a exterior surface proximate to a twist-on
wire connector
having a wire engaging surface; placing a lubricant on either the exteriors
surface or the wire
engaging surface; and rotating the electrical wire to create a contact area
between the wire
engaging surface and the exterior surface and continuing to rotate the
electrical wire to form
an increased contact area having a low electrical resistance there across.
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