Note: Descriptions are shown in the official language in which they were submitted.
21641i6~
IMPROVED ELECTRICAL CONNECTOR
Field of the Invention
The present invention relates to electrical connec-
tors; and more particularly, it relates to pin and socket
electrical connectors of the type used in many industrial uses
for low power, signal communications or control signal appli-
cations.
Backqround of the Invention
The female contact of current commercial pin and
sleeve electrical connectors, in one common form, has two
opposing, semi-cylindrical fingers (or "beams" as they are
sometimes called). Together, they form an elongated,
cylindrical socket or female receptacle for a male connector
pin, both fingers being integral with and ext~n~ing from a
common base in cantilever. Thus, each of the fingers extends
from a common base, outwardly in a semi-cylinder to a distal
end. Together they form a split cylinder--i.e., the socket.
The semi-circular distal ends of the two fingers form an inlet
opening to the socket through which the pin is placed in mak-
ing a connection.
A cylindrical sleeve is located around the outer
edges of the fingers and it extends from the base of the
fingers to a location short of the outermost or distal ends of
the fingers. In other words, the outermost ends of the
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fingers, in the prior art, extend out of the sleeve at the
location where they receive the connector pin in mating coup-
ling. The cylindrical sleeve thus limits the outward flexing
of the fingers at their base, but it leaves the inlet ends
free, where damage can occur.
- Typically, connectors of this type have two through
five or more poles, each pole being represented by a mating
pin of a male connector and a corresponding socket of a female
connector. All of the connector elements for both the male
and the female connectors are held in place by a plastic body
called an insert. An electric cable having a conductive wire
for each pole is assembled to each male and female connector,
with a wire attached to each connector element; and a covering
or sheath of soft insulating plastic is molded to bridge the
jacket of the cable to the insert, thereby enclosing and seal-
ing the connections of the electrical wires to the connector
elements. Thus, these connectors are frequently referred to
in the industry as "molded" connectors.
In connectors of this type, the primary mechanism
for limiting the diameter of a pin being inserted is the open-
ing formed in the plastic insert body just beyond the outer-
most extension of the fingers. However, the insert body,
being formed of a pliable, molded plastic, deforms under
force, so that it is not uncommon for a person to attempt to
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assemble a male connector having oversized pins into a corre-
sponding female connector. This may lead to damage.
Experience has shown there are two problems with the
female connector in the prior art structure. It must be
realized that molded connectors are typically used in indus-
trial or commercial applications and that they experience
rugged conditions of use. The pins may be stepped on or
otherwise mishandled so that one or more of the pins become
misaligned (i.e., out of parallel) with the other pins of the
male connector. During assembly to a female connector, a
misaligned pin may cause damage to the socket. In assembling
the male connector to a female connector, even if the pins are
not misaligned, molded connectors are frequently subjected to
rough handling so that one or more of the pins of the male
connector are not properly aligned with the axis of the asso-
ciated female socket into which it is being inserted. This
can also cause damage to the socket elements.
Thus, a common failure is caused by misalignment of
the pin during insertion. This can cause a bending of the
flexible finger at the inlet opening of the socket because the
finger extends beyond, and is therefore not supported by, the
surrounding metal cylindrical sleeve. The damage is exacer-
bated because of the shape of the fingers (i.e., semi-
cylindrical) and because of the characteristics of the type of
brass material from which these contacts are conventionally
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made. That is, they are machined from a brass alloy which is
somewhat brittle so that it rather easily is deflected beyond
its normal stress-deflection characteristic. When this
occurs, the metal is overstressed and may even tear. In
either case, it will lose its resilient characteristic; and
its ability to establish reliable electrical continuity is
then lost.
A second problem which also results from the stiff-
ness and shape of the semi-cylindrical fingers of the prior
art construction is that they are susceptible to damage if a
pin having a diameter larger than that for which the female
connector is designed, is inserted into the female socket.
Again, the rugged conditions of industrial applications must
be borne in mind. It is not uncommon for a user to force an
oversized pin into a smaller socket. If an oversized pin is
attempted to be assembled to a smaller female socket, the
inlet ends of both semi-circular fingers are bent outwardly
and about the edge of the protecting sleeve where failure
occurs if the fingers are bent with sufficient force.
Summarv of the Invention
The present invention improves the female socket of
a pin and socket connector to overcome the two common failure
modes mentioned above--namely, bending of the flexible fingers
of the female socket beyond their normal stress limits due to
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either an attempt to insert an oversized pin, or the insertion
of a normal size pin but in a misaligned orientation relative
to the axis of a socket. Both of these failure modes cause,
as mentioned above, flexure of the flexible fingers of the
female socket beyond their normal stress limits so that the
neCpccAry resilience of the fingers is lost.
The present invention improves the force/deflection
characteristics of the flexible fingers by reducing the cir-
cumferential extension of the fingers. Thus, rather than
having the fingers extend in a radial arc (or "sector") of
approximately 180 about the axis of the female socket,
whereby the flexible fingers form a semi-cylinder, the present
invention provides that the fingers extend through a sector of
approximately 90 so that there are four separate fingers,
arranged in quadrature about the axis of the socket. Each
individual finger moreover, is much more "flat" in the sense
that its connection to the base of the connector element is of
reduced arc and reduced extension. Thus, the fingers of the
present invention are more flexible for a given force than are
the fingers of the prior art, even when they are made of the
same material as the prior art, due to the structure just
described.
A metal sleeve surrounds the fingers and extends
beyond their free ends to form an inwardly turned, rearwardly
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extending continuous lip forming an annular guide surface
which defines the inlet aperture to the socket.
The protective structure of the annular lip of the
sleeve and the additional flexibility of the fingers cooperate
to provide an improved female socket for a pin connecting ele-
ment, with greater reliability of electrical continuity and
having a substantially increased ability to withstand the
rugged conditions of use for molded connectors of this type,
without improved reliability.
Other features and advantages of the present inven-
tion will be apparent to persons skilled in the art from the
following detailed description of a preferred embodiment
accompanied by the attached drawing wherein identical refer-
ence numerals will refer to like elements in the various
views.
Brief Description of the Drawinq
FIG. 1 is a side view of a molded connector in the
prior art, with the cable foreshortened;
FIG. 2 is a left side view of the prior art connec-
tor of FIG. l;
FIG. 3 is a vertical sectional view of the prior art
connector of FIG. 1, taken parallel to the plane of the page;
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FIG. 4 is an enlarged side view of the female con-
nector element of the prior art connector of FIG. 1 with por-
tions shown in section;
- FIG. S is a left side view of the female connector
element of the prior art shown in FIG. 4;
~ FIG. 6 is a side view of an improved female connec-
tor element constructed according to the present invention
with portions shown in section;
FIG. 7 is a partially sectioned side view of the
sleeve of the improved female connector element;
FIG. 8 is a side view of the improved female connec-
tor of the present invention with the sleeve assembled to the
connector element, but with the upper left hand portion of the
sleeve and the socket partially sectioned to show the interior
thereof; and
FIG. 9 is a left side view of the female connector
element shown in FIG. 6.
Detailed Description of a Preferred Embodiment
Referring first to the prior art connector shown in
FIGS. 1-5, reference numeral 10 generally designated a female
molded connector. The connector 10 includes a body 11 of low
durometer (that is, flexible) plastic in which female connec-
tor elements, described below, are embedded. The combination
of connector body 11 and connector elements is referred to as
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an insert. The connector elements are, in turn, connected to
individual wires such as those designated 12 in FIG. 3 which
are enclosed in an insulating cover or sheath generally
designated 13 to form a multi-conductor cable generally
designated lS.
- After the electrical connections are made between
the wires 12 and the female connecting elements of the insert,
one of which is designated 16 in FIG. 3, a portion of the
connector designated 17 is molded to seal the cable 15 to the
insert 11. The molded body 17 not only hermetically seals the
electrical connections made between the wires and the connec-
tor elements, but it also provides mech~nical strength and
cushioning protection to the wires and the connector body and
elements.
For reference purposes, when referring to various
parts of the connector, the ~ inner end is the one closest to
the cable 15, and the "outer" end or portion is that which is
closest to the male pin connector during assembly.
The connector body 11 is provided with a circum-
ferential rim 18, and an internally threaded coupling nut 19
is located on the insert body 11 to mechanically couple with a
correspondingly threaded exterior screw portion of a mating
male connector having pins. The pins are received in sockets
generally designated 20 of the female connector elements so
that after the male connectors or pins are inserted into the
21B~S6~
sockets 20 of the female connectors 16, the nut 19 is screwed
onto a corresponding exterior thread attached to the insert of
the male connector, and the connectors are secured together in
a manner familiar to those skilled in the art.
Referring now in particular to FIGS. 4 and 5, the
socket 20 includes first and second semi-cylindrical fingers
21, 22 extending from a base 23 of the female connector ele-
ment. These fingers are typically formed by ma~-h;ning the
cylindrical bore into the body of the female connector element
to the desired depth and then forming a single cut 23a dia-
gonally across the socket and through the axis of the bore.
A cylindrical metal collar 24 surrounds the fingers
21, 22. The interior surface of the collar 24 is spaced
slightly outwardly of the outer surface of the fingers 21, 22
to permit the fingers to flex, and the collar extends in an
axial direction from a raised annular rib 25 of the base 23 to
a location defined by edge 24a located slightly inboard of the
free ends of the cantilever fingers 21, 22, leaving the free
ends, such as that designated 2la, unprotected by the sleeve
24.
Turning now to FIGS. 4-7, there is shown the im-
proved female or socket connector element of the present in-
vention. Persons skilled in the art will appreciate that
there is a female connector element for every corresponding
male pin connector element, and that the improved female ele-
216~6~
ments are embedded in a connector body and connected to thewires of the associated cable as they have been in the past.
Turning then to FIG. 6-8, the improved female or
socket connector element is generally designated 26. It in-
cludes a cylindrical base 27, a pair of circumferential barbs
28 to secure the female connector element in its associated
connector body, and a set of four flexible fingers designated
30, 31, 32 and 33 in FIG. 9. The fingers 30-33 are arranged
in quadrature to form a socket generally designated 35 in FIG.
6 for receiving an associated pin connector. The sides of the
fingers 30-33 are defined by slots 34-37.
As indicated in FIG. 9 the fingers 30-33 each extend
about the axis of the socket for a sector of slightly less
than 90 (i.e., 90 less the width of a slot). The inner
surface of the outer edge of each finger is beveled at 30, as
seen at 33a and 32a for fingers 33 and 32 respectively in FIG.
7. All of the fingers have pin-engaging surfaces forming
sectors of a cylinder, similar to those found in conventional
sockets.
As mentioned above, it will be observed from FIG. 9
that each of the fingers or beams extends in a radial sector
arc of approximately 90; and it can also be observed that
each of the quadrature fingers is substantially more flat
(i.e., when viewed on end) than the two semi-cylindrical
fingers of the prior art shown in FIG. 5. These flatter con-
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tours not only provide more flexibility to the individual
fingers relative to their base, but they exhibit a much lower
tendency toward tearing or excessive stressing of the metal if
the fingers are bent backward on themselves. (By "backward",
it is meant that the outermost portion of the finger is bent
relative to the base by moving it in a direction radially away
from the axis of the socket.) Persons skilled in the art will
thus appreciate that the fingers may be made even more flat
than shown in FIG. 9 by increasing the number of fingers, for
example, to six or eight, while attaining the advantages of
the present invention.
The inner portion of the base 27 of female connector
element 26 there is formed into a receptacle generally desig-
nated 39 for receiving a wire from its associated feed cable.
The wire may be crimped or soldered in place, providing both
electrical and mechanical connection at the same time.
Turning now to FIGS. 7 and 8, reference numeral 40
generally designates a sleeve having a cylindrical wall 41 and
an inwardly turned annular lip 42. The sleeve 40 is received
over, and surrounds, the quadrature finger arrangement of the
socket 35, and the innermost end of the sleeve (that is, the
end opposite the inwardly turned lip 42) is received on a neck
portion 45 adjacent the base of the quadrature finger socket
35 in an interference fit.
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The length or axial dimension of the sleeve 40 is
such that when the innermost end of the sleeve is forced onto
the collar 45 of the female connector element, the inner or
free edge 42a of the lip 42 is slightly outboard of the free
or distal end 45 of the cantilever fingers 30-33 (see FIG. 8).
Thus, the fingers are free to flex outwardly, but a pin being
inserted is centered on the axis of the socket due to the
guiding action of the annular lip 42. Moreover, it will be
appreciated that the cylindrical wall 41 of the sleeve 40 is
spaced slightly radially outwardly of the fingers 30-33 so as
to permit them to flex; but at the same time, the cylindrical
wall 41 acts as a limit for the outer flexing of the fingers
throughout their entire length. That is, no part of any
finger may be bent outside the contour of the wall 41 of the
sleeve. Moreover, the inner surface of the inwardly turned
lip 42 of the sleeve 40 acts both as a guide in inserting a
pin into the female socket, and also as a limit for the dia-
meter of pin that may be inserted. This is in contradistinc-
tion to the prior art which, as described above, used the soft
plastic, such as polyvinylchloride, material of the insert
body not only to guide the pin being inserted into the socket,
but also to limit the size of the pin being inserted.
The guiding function of the lip 42 is enhanced be-
cause it is of progressively reduced diameter proceeding in
the direction of pin insertion, best seen in FIGS. 7 and 8.
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In summary, the present invention provides an im-
proved cantilever beam or flexible finger type of female
socket for an electrical connector element having enhanced
flexibility, greater reliability in establishing repeated
electrical contacts, and greater resistance to misuse either
by the insertion of misaligned pins or the insertion of pins
having a diameter larger than that for which the socket is
designed to receive.
Another advantage of the present invention, which is
not apparent from the above description, is that in the manu-
facturing operation, a wider variation in a critical tolerance
is permitted with the quadrature beam structure of the present
invention than was permitted with the dual-beam structure of
the prior art shown in FIGS. 1-5. To understand this
advantage, it must first be understood that in manufacturing,
a tolerance is set on the inner diameter of the socket, after
it is formed. Next, the slots in the side wall of the socket
are formed to define the fingers. This is so in manufacturing
both dual-beam structures and quadrature beam structures.
Next, the fingers are "spanked" (i.e., formed under pressure
to a reduced diameter) and the diameter of the socket then
must meet established tolerances in order to exert the
required pressure on an inserted pin to establish reliable
electrical continuity in the connector. This tolerance of the
diameter of the bore of the socket, after spanking, is greater
21~6~a
for the quadrature beam structure of the present invention.
This reduces manufacturing costs.
Having thus disclosed in detail a preferred embodi-
ment of the invention, persons skilled in the art will be able
to modify certain of the structure which has been illustrated
(for example, by adding fingers), and to substitute equivalent
elements for those disclosed while continuing to practice the
principle of the invention; and it is, therefore, intPn~
that all such modifications and substitutions be covered as
they are embraced within the spirit and scope of the appended
claims.
