Note: Descriptions are shown in the official language in which they were submitted.
CA 02636225 2008-06-26
ONE-PIECE PUSH-IN ELECTRICAL CONTACT TERMINAL
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to electrical connector
components and more particularly to a one-piece push-in electrical contact
terminal,
designed to accept both stripped solid and stranded wire, which provides a
means for
mechanically and electrically terminating the wire.
[0002] Industry standards are oftentimes established as a means of insuring
the safety of the installer and for the end-user. For example, the National
Electric
Code (NEC) has implemented regulations requiring all fluorescent lighting
fixtures to
have a means of electrically isolating their components so as to increase the
safety of
working on them or replacing their parts in the field. This new provision is
intended
to standardize the ability to safely disconnect various electrical components
from both
a power source as well as a ground or neutral wiring. This requirement is
expected to
apply particularly to fluorescent tube lamps and their associated ballasts.
[0003] As can be appreciated, there are many different types of electrical
connectors for use in such fluorescent fixtures that are capable of being
easily
connected and disconnected. In particular, they are all quite capable of
safely de-
energizing or removing an electrical component from a circuit (power or
ground) so
that it may be serviced in confidence. Of course, while proper technique tries
to avoid
pulling of the wires to separate the connector, in practice, this may be
exactly what
CA 02636225 2008-06-26
actually occurs. Pulling directly on the wires instead of the connector is
likely to
weaken the connection between the wire and the electrical contact within the
connector. In some cases, the wire is soldered or crimped to the contact, in
other
cases the wire is simply inserted into an insulation displacement contact or
pushed
into the connector. Such mishandling (i.e. pulling on the wires instead of the
connector) can cause these joints to separate, the consequence being the
separation of
the wire from the contact terminal thereby rendering the connector unusable.
[0004] It is, therefore, desirable to provide an electrical contact for use in
a
separable electrical connector with structural features to enhance retaining
of the
wires to the contact even under conditions of repeated mishandling. It is
further
desirable to provide a new contact terminal design that is better at resisting
such
mishandling and which can be repeatedly used to safely break or disrupt the
electric
circuit to a component being replaced or serviced. It is still further
desirable to
provide an electrical contact that can withstand repeated disconnections and
re-
connections by various workers without affecting its ability to provide a low
resistance electrical connection.
SUMMARY OF THE INVENTION
[0005] The present invention is an electrical contact terminal for an
electrical
connector, which generally includes a main contact body, a cantilevered
portion
extending upwardly from one end of the body and a stiffener extending the
entire
length of the main contact body for providing rigidity to the main contact
body.
2
CA 02636225 2008-06-26
[0006] In a preferred embodiment, the stiffener comprises two substantially
parallel ribs disposed on the body. The ribs are preferably laterally spaced a
distance
equal to a diameter of a conductor of the wire received by the cantilevered
portion,
whereby the ribs are configured to receive the conductor therebetween. Also,
the
cantilevered portion preferably includes a wire opening formed therethrough,
wherein
the ribs are disposed on opposite sides of the wire opening.
[0007] The contact terminal of the present invention further preferably
includes a tongue member extending outwardly from an end of the main contact
body
opposite the cantilevered portion. Specifically, the cantilevered portion
extends from
the main contact body at a junction thereof and the tongue member extends from
the
main contact body at a junction thereof. The stiffener thus extends from the
cantilevered portion juncture to the tongue member juncture.
[0008] The tongue member preferably includes a step portion extending
upwardly from the opposite end of the main contact body and a tongue portion
connected to the step portion in such a manner that the tongue portion is
laterally
spaced and substantially parallel with the main contact body. Moreover, the
step
portion preferably includes a wall surface facing the cantilevered portion for
stopping
further insertion of a wire in the cantilevered portion.
[0009] The present invention further involves an electrical connector that
generally includes a contact terminal and a housing defining a chamber for
containing
the contact terminal. The contact terminal includes a main contact body, a
3
CA 02636225 2008-06-26
cantilevered portion extending upwardly from one end of the main contact body
and a
stiffener extending the entire length of the main contact body for providing
rigidity to
the main contact body. The cantilevered portion is configured to receive a
wire
inserted therein in an insertion direction and the housing includes an
internal ledge
adjacent the chamber for preventing the cantilevered portion of the contact
form
bending in a direction opposite the wire insertion direction.
100101 A preferred form of the electrical contact, as well as other
embodiments, objects, features and advantages of this invention, will be
apparent
from the following detailed description of illustrative embodiments thereof,
which is
to be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 is a top plan view of a push-in contact terminal formed in
accordance with the present invention.
[0012] Figure 2 is a top perspective view of the contact terminal shown in
Figure 1.
[0013] Figure 3 is a side plan view of the contact terminal shown in Figure 1.
[0014] Figure 4 is a front plan view of the contact terminal shown in Figure
1.
4
CA 02636225 2008-06-26
[0015] Figure 5 is a cross-sectional view of a separable connector employing
two contact terminals of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0016] An electrical contact terminal 10 of the present invention is shown in
Figures 1-4. These contact terminals are of the "push-in" variety and are
often used in
such electrical connectors as disconnects. The contact terminal 10 is
generally
manufactured from a single piece of electrically conductive material. Such
contact
terminals are generally punched out from a larger sheet of material and then
are rolled
or bent or otherwise configured into the desired shape. It may be appreciated,
however, that multi-component terminals may be employed in the present
invention.
[0017] The contact terminal of the present invention generally includes a main
body 12, a cantilevered portion 14 extending upwardly from one end of the body
and
a tongue member 16 extending outwardly from the opposite end of the body. The
cantilevered portion 14 extends upwardly from the body 12 at a reverse acute
angle
with respect to the planar body. The cantilevered portion includes a wire
opening 18
into which a center conductor 102 of a wire 100 would be pushed or inserted as
shown in Figure 5. Cantilevered portion 14 may also include some type of
insulation
displacement push-in device (not shown) that is used instead of wire opening
18 if
that design is so desired. Such featured device is disclosed in the U.S. Pat.
No.
4,455,057 to Mariani and the U.S. Pat. No. 4,461,527 to Izraeli, both of which
are
incorporated herein by reference.
5
CA 02636225 2008-06-26
[0018] The cantilevered portion 14 is further preferably configured with a
reverse-bent retention finger 20 that extends back towards main body 12. This
reverse-bent retention finger 20 retains the wire 100 in compressive
engagement
against electrical contact terminal 10 in the normal fashion after such wire
is pushed
through opening 18, as shown in Figure 5. The retention finger 20 preferably
terminates at a sharp distal edge 22 for "digging-into" the center conductor
102 of the
wire 100. However, the end 22 of the retention finger 20 can take many
different
configurations for grasping the wire 100.
[0019] As a withdrawal force is applied to the wire 100 in a direction
opposite
to the wire insertion direction, as shown by the arrow A shown in Figure 5,
the angled
bend between cantilevered portion 14 and the main body 12 will be flexed. Any
such
flexing of the body 12 will increase the angle of this bend thereby
significantly
altering the angle at which reverse bent retention finger 20 engages the wire.
Any
slight variation of this angle may permit the wire to undesirably separate
from
electrical contact terminal 10.
[0020] The present invention therefore incorporates a stiffener 24 in the body
12 extending between the juncture 26 of the cantilevered portion 14 with the
body
rearwardly to the juncture 28 of the tongue member 16 with the body. Thus, the
stiffener 24 extends the entire length of the body 12.
[0021] The stiffener 24, in the preferred embodiment of the present invention,
takes the form of two parallel ribs 30 extending between the juncture 26 of
the
6
CA 02636225 2008-06-26
cantilevered portion 14 with the body rearwardly to the juncture 28 of the
tongue
member 16 with the body. For reasons that will be explained in further detail
below,
the ribs 30 are preferably spaced laterally from each other a distance
matching the
diameter of the center conductor 102 of the wire 100 and are positioned on
opposite
sides of the wire opening 18. The ribs 30 are preferably stamped or embossed
portions of the body 12 formed during the stamping and bending process for
manufacturing the contact 10. Alternatively, it is possible to add additional
material
to the body 12 to form the two ribs 30 extending the length of the body to
make the
body more rigid and less likely to deflect or deform.
[0022] Since the ribs 30 extend into the juncture 26 of the cantilevered
portion
14 with the body 12, the ribs prevent the body from flexing or bending during
a wire
pull-out load. Thus, the body 10 is now strengthened or stiffened and less
likely to
flex or bend under a wire pull-out load. On the other hand, the cantilevered
portion
14 is permitted to flex so that the retention finger 20 will sufficiently
grasp the center
conductor 102 of the wire 100 as described above. As a result, the wire 100 is
more
securely mechanically attached to the electrical contact terminal 10. This
will ensure
that the wire 100 remains attached to the contact terminal 10 during repeated
connections and disconnections and especially if the wire is connected to the
contact
terminal via the method of attachment shown here that employs reverse bent
retention
finger 20.
[0023] Moreover, the stiffening ribs 30 form a valley or trough that functions
as a wire guide for receiving the center conductor 102 of the wire 100. As
shown in
7
CA 02636225 2008-06-26
Figure 5, the ribs 30 extend along and on opposite sides of the center
conductor 102
of the wire 100 that is pushed or inserted through the wire opening 18 of the
contact
10. These ribs 30 help to channel and retain the center conductor 102 of the
wire 100
under the retention finger 20, and thus in electrical and mechanical
engagement with
the contact 10. The wire opening 18 and the spacing between the ribs 30 can be
chosen to accept a variety of different wire gauges, but it is expected that
the wire
opening 18 would typically be designed to receive smaller wires, such as a
wire
ranging between 12-18 gauges.
[0024] As described above, the tongue member 16 extends outwardly from the
end of the body 12 opposite the cantilevered portion 14. The tongue member 16
preferably includes a step portion 32 and a tongue portion 34. The step
portion 32
extends upwardly from the juncture 28 of the tongue member 16 with the body 12
and
the tongue portion 34 is connected to the step portion so that the tongue
portion
extends generally parallel, but laterally spaced from the plane of the body
12. This
offset arrangement provides added stiffness to the body 12.
[0025] In this manner, the wall surface 36 of the step portion 32 facing the
wiring opening 18 of the cantilevered portion 14 forms a wire stop for the
center
conductor 102 of the wire 100 inserted into the contact 10. Specifically, the
step
portion 32 of the tongue member 16 is spaced from the wire opening 18 of the
cantilevered portion 14 a distance equal to a standard length of the center
conductor
102 bared during wire preparation. For example, where it is standard practice
to strip
the outer insulation from wires a distance of three-eighths (3/8) inch for a
given
8
CA 02636225 2008-06-26
connector installation, the step portion 32 for the contact 10 used in the
connector of
this installation would be spaced three-eighths (3/8) inch from the wire
opening 18 of
the cantilevered portion 14. The wire stop 36 provides a positive bank stop
for proper
insertion of the wire 100 into the contact 10 and prevents the wire from being
inserted
too far into the contact.
[0026) Figure 5 shows the contact 10 in use in a typical connector assembly
40 including a female connector 42 adapted to connect with a male connector
44. The
female connector 42 includes a housing 46 defining a chamber 48 for receiving
the
contact 10 of the present invention therein. The housing 46 is typically made
from an
insulative material, such as polycarbonate or nylon or another insulating
material. A
retaining member 50 may be provided to retain the contact 10 within the
chamber 48
of the housing 46.
[0027] Similarly, the male connector 44 includes an insulative housing 52
defining a chamber 54 for receiving the contact 10a of the present invention
therein.
Again, a retaining member 56 may be provided to retain the contact l0a within
the
chamber 54 of the housing 52. In this case, however, the contact l0a includes
a
tongue member 16a adapted to mate with the tongue member 16 of the contact 10
provided in the female connector 42.
[00281 Although the drawings show the mating tongue members 16, 16a in a
spade configuration, any push-in style mating contact design known in the art
can be
utilized including, but not limited to, ring, fork, sleeve, ferrule, quick
disconnect or
9
CA 02636225 2008-06-26
pin type contact style terminals. Alternate electrical connector component
designs are
also possible or such components may be employed in other types of electrical
connectors such as an interconnect or a splice that is used to join a wire or
cable to
another or to an electrical device. Thus, the present invention is not limited
to the
type of electrical connector employed.
[0029] The retaining members 50, 56 of the female and male connectors 42,
44 each preferably include an integral angled ledge 58 to contact and confine
the
cantilevered portion 14 of the contact 10, 10a. Thus, as the wire 100 outside
the
connector 42, 44 is mishandled and tugged backward in a negative direction,
the
external load also pulls the cantilevered portion 14 as well. However, because
the
ledge 58 obstructs the cantilevered portion 14 from being pulled back, the
wire
retention finger 20 flexes, enabling the finger to bear down on the wire to
grasp it
even more firmly.
[0030] Only one contact 10, l0a is shown in the connectors 42, 44 of Figure
5. However, it can be appreciated that these connectors 42, 44 may contain a
plurality
of mating contacts 10, l0a of the present invention. Moreover, while a male-
female
disconnect system is shown, it is also conceivable to supply one end of the
disconnect
interface with integral leads for termination directly to a ballast or for
wiring into the
ballast leads.
[0031J Although the illustrative embodiments of the present invention have
been described herein with reference to the accompanying drawings, it is to be
CA 02636225 2008-06-26
understood that the invention is not limited to those precise embodiments, and
that
various other changes and modifications may be effected therein by one skilled
in the
art without departing from the scope or spirit of the invention.
[0032] Various changes to the foregoing described and shown structures will
now be evident to those skilled in the art. Accordingly, the particularly
disclosed
scope of the invention is set forth in the following claims.
11
