Note: Descriptions are shown in the official language in which they were submitted.
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The present inven-tion is related to and an improve-
ment upon the invention disclosed in U.S. Patent ~,120,556,
issued October 17, 1978 and entitled "Electrical Contact
Assembly". This patent is assignecl by inventors C. R. Waldron
et al. to the assignee oE the present invention, and is herein
sometimes referred to as the "Three-Piece Contact Patent".
The present invention is also rela-ted to U.S. Patent
4,072,39~ to C. R. Waldron et al., for "Electrical Contact
Assembly". This patent is also assigned to assignee of the
present invention and is sometimes referred to as the "Alternate
Three-Piece Contact Patent".
The invention disclosed in copending Canadian Patent
Application, Serial No. 370,335, filed on February 6r 1981 date,
of D. L. Pfendler and E. J. Bright and which is sometimes
referred to as the "Pfendler/Bright Patent".
TECHNICAL FIELD
This invention relates to electrical connectors of
the type having an outer shell or housing; a plurality of
electrical contacts, each of which are electrically a dielectric
insert or insert assembly mounted to the housing ~or either
fixedly or removably mounting the electrical contacts in the
shell electrically isolated from other conductors. This
invention is more particularly related to an improved electrical
contact assembly.
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BACKGROUND OF THE INVENTION
A variety of electrical contacts have been suggested
in the prior art. A variety of methods of making such
contact also have been suggested in the prior art. Ad-
vantageously the contact will be inexpensive and simple
to manufacture and assemble, having superior electrical
properties, and have good mechanical characteristics
(resistance to conductor "pull out" or undesirable con-
tact disassembly).
10The Three-Piece Contact Patent describes an elec-
trical contact (and method of making it) somewhat similar
to the present invention. The electrical contact
described therein, however, presents possible
- manufacturing and assembly difficulties which could lead
to quality and reliability problems in electrical or
mechanical properties. The contacts in that patent are
shown to have four elongated slots~ Typically, the four
slot sleeve ~shown therein) is crimped in place by a
crimping mechanism having four radially spaced crimper
20members. Tbe elongated slots could coact with the equal
number of crimpers to provide an unreliable mechnical and
electrical connection.
The Pfendler/Bright patent addresses this problem by
providing an arrangement of slots unequal to the number
of crimpers and provides internal grooves in the sleeve.
While such a design works well, the removal of so much
mateiral (to Eorm slots) may be undesirable in some
i~ instances by reducing mechani~cal and electrical
`~ characteristics of the contact.
30In other embodiments, electrical contacts are
machined from cylindrical metal stock. In these machined
-~ contacts, very close manufacturing tolerances ~0.002
inches or less) are frequently desired to avoid oversized
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contact parts. An oversized contact may not be insert-
able into connector apertures designed to receive the
contacts. Further, an insufficient clearance, caused by
either an undersized or oversized part, could prevent
proper electric or mechanical operation of the contact.
Machined contacts are also generally relatively ex-
-pensive to manufacture when machine and operator costs
are considered. Further, the weight of a machined con-
tact is typically greater than the weight of a stamped
and formed contact as descr;bed in present invention.
While individual contact weight is generally small, an
aircraft requires a very large number of contacts and
every extra gram of aircraft equipment (e.g., in the con-
tacts) displaces a gram of potential load, since the
maximum weight for equipment and load is specified for
the aircraft.
Machined contacts are also disadvantageous in that
the machines producing them are time-consuming and diffi-
cult to set up and inherently produce a parts output
which have a relatively wide dimensional range. This
dimensional range requires a costly post-manufacture in-
spection, at which a significantly number of machined
parts may be rejected or discarded as not meeting speci-
fications. The reject problem significantly raises the
costs of good parts.
Some prior art electrical contacts which are stamped
and formed into a shape having a seam which is welded or
brazed together. The added step of welding or brazing the
seam adds an extra step to the manufacturing process and
the step is difficult to accomplish accurately in view of
the small dimensions which are involved in contact manu-
facture.
Examples of such prior art contacts are shown in
U.S. Patents 2,689,337; 2,804,602; 3,125,396; 3,137,925;
3,314,044; 3,316,528; 3,317,887; 3,6~8,224; 3~660,805;
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3,721,943; 3,920,310; French paten~ 1,447,759 and German
Patent 60,347.
Accordingly, the prior art contacts present various
and sundry limitation and disadvantages (depending on the type
of contact selected).
According to the present invention there is pro~ided
an electrical contact assembly which has a tu~ular liner with
a front mating portion, a reàr wire receiving portion and a
center portion with the rear wire receiving portion including a
plurality of axially spaced grooves extending around the
internal periphery thereof and having a plurality of holes
extending therethrough. The holes are arranged in an axial and
- radial pattern in the rear wire receiving portion. A sleeve
is telescopically mounted oYer at least one portion of the
tubular liner and is secured thereon.
The present contact assem~ly includes the sleeve
stamped to have an arrangement of holes in a conductor-receiving
rear portion and advantageously includes a plurality of internal
grooved indentations extending circumferentially around the
conductor-receiving portion forwardly of some, but preferably
not all of the holes. More specifically, the holes are arranged
in sets of a pair of axially-spaced closely adjacent holes,
with a third hole spaced axially at a signifi~antly greater
distance. Sets of holes are repeated at several (e.g. four)
radial locations. In a specific embodiment, the holes are small
and round and of uniform size, allowing the sleeve to be easily
crimped whlle retaining su~stantial sleeve portions for
mechanical (conductor retention~ and electrical (current and
signal transmission) purposes.
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The electrical contact of the present invention has
the advantage that it is lower weight and higher quality than
that of prior art machined contacts.
The present invention also has the advantage that it
has better electrieal and meehanieal eharaeteristies that the
eontaet deseribed in the Three-Pieee Contaet Patent or the
Alternate Three-Pieee Contact patents referred above.
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The preferred embodiment of the present invention is
a three-piece electrical contact assembly including a
sleeve that is stamped and fol-med from a piece of sheet
metal and is characterized by a tubular inner sleeve
which has an unwelded seam and twelve holes arranged in a
pattern of four holes symmetr:ically radially at each of
three axial location in the rear of the sleeve when
formed into a tubular shape. A conductor is secured
within the sleeve by ~eing crimped in place with crimps
engaging each of the sets of holes.
It is also an object of the present invention to re-
place the expensive machine contacts with a less expen-
sive, yet high quality, stamped and formed contact of the
present invention.
It is also an object of the invention to provide an
electrical contact which, when stamped from sheet metal,
formed into a cylindrical shape and crimped to a conduc-
tor, makes a good mechanical attachment and good electri-
cal connection to the conductor.
It is still another object of this invention to pro-
vide an electrical contact which can be fabricated rather
easil~ in large ~uantities at low cost with relatively
low number of unacceptable parts.
It is still a further object of the present inven-
tion to provide an inexpensive electrical contact which
is of lower weight than machined electrical contacts.
The foregoing and other objects, advantages and fea-
tures of the present invention will become apparent to
those skilled in the art, in view of the following des-
cription and claims, taken in conjunction with the
accompanying drawings which form a part of this appli-
cation.
39l3
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a top view of a contact sleeve stamped
as a flat piece, prior to forming into a three-dimension-
al cylindrical shape.
FIGURE 2 iS a partial cross-sectional view of the
contact sleeve of FIGURE 1, aEter it has been formed to
its tubular or three-dimensional shape.
FIGURE 3 iS a partial cross-sectional view of a
second piece of the contact assembly of the present in-
vention.
FIGURE 4 is a partial cross-sectional view of a
third piece of the electrical contact assembly of the
present invention.
FIGURE 5 shows a subassembly of the first and second
pieces of the electrical contact assembly of the present
invention.
FIGURE 6 is a partial cross-sectional view of the
assembly of FIGURE 5, looking along the line VI-VI,
looking in the direction of the arrows.
FIGURE 7 is a top view of the assembly portion of
FIGURE 6, looking along the line VII-VII, looking in the
direction of the arrows.
FIGURE 8 is a partial cross section of the three-
piece assembly.
FIGURE 9 iS an alternate embodiment of the sleeve of
FIG~RE 1.
FIGURE 10 is another alternate embodiment of the
sleeves of FIGURES 1 and 9.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a top view of a one-piece contact sleeve
member 10 showing elements of the present invention. The ?
sleeve member 10 is shown as it is initlally formed, a
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flat piece of sheet metal or other electrically con-
ducting material, stamped in substantially the shape
shown.
irhe sleeve member 10 includes a forward contact
section 12, a medial section 14, and a rear conductor-
receiving section 16. The forward contact section 12 in-
cludes two (or, alternatively a plurality of) projections
13 which taper to narrower forward ends. The projections
become spring fingers for receiving a male or pin-type
electrical contact in both mechanical contact and an
electrical circuit relationship after the sleeve member
is formed into its three-dimensional cylindrical shape.
The medial section 14 spatially connects and elec-
trically joins the forward contact section 12 and the
rear conductor-receiving section 16. The rear conduc-
tor-receiving portion 16 includes a plurality of grooved
depressions or indentations 18 extending transverse to
the length of the sleeve member 10 and transverse to the
axis of the cylindrically-shaped sleeve member 10 (when
formed). These grooves 18 are formed on the inside side
of the sleeve member 10 when it is formed into its three-
dimensional cylindrical shape.
The rear section 16 also includes a plurality of
holes generally circular and of small diameter with
respect to the width of the sleeve member 10. At each of
four radial locations (when the sleeve is formed into its
cylindrical shape) there are three axially spaced holes
l9a, l9b, l9c, with two holes (19a, l9b) being spaced
closely, for example by approximately 1-2 times the hole
diameter, and the third hole being spaced by a greater
distance, for example by three or more hole diameters.
When the sleeve member 10 is formed into its cylindrical
shape, a set of holes is formed along the seam, as first
hole halves l9d cooperates with second hole halves l9e to
form a single set of holes. These radially spaced holes
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and hole portions are separated by a unifor~ lateral
spacing to provide a uniform angular (radial) separation
of the hole sets when the contact sleeve portion is
formed into its cylindrical shape.
FIGURE 2 shows the contact sleeve member 10 ~ormed
into a cylindrical shape by forming the sleeve 10. The
sleeve member 10 is symmetrical about an axis which is
parallel to the length of the sleeve portion and the
slots. The forward contact section 12 has the spring
fingers 13 converging to its forward end for receiving
the pin-type contact therein. The grooved indentations
18 are shown in the cut-away portion extending circum-
ferentially around the inside portion of the sleeve
member 10 of FIGURE 2. The grooves 18 are preferably
located forwardly of at least the rear holes (19a, l9b)
but within the rear contact receiving section 16.
A rear end portion 21 of the contact body is flared
radially outwardly for more ease in inserting an elec-
trical conductor therein. The hole halves l9d, l9e meet
at a seam 22 to form a single set of holes, generally
similar in shape to the other hole sets 19.
The contact sleeve portion 10 is crimped after a
conductor is inserted into the rear end thereof to retain
the conductor therein. Existing crimping apparatus are
well known and generally have a plurality of radially
spaced crimping elements, including four bi-lobed
elements spaced 90 degrees apart in the preferred
embodiment. Applicants preferred structure is
specifically disclosed to have holes axially arranged to
fall under or near each of the lobes, as, for example,
holes l9c falling near one lobe with the other lobe
falling near holes l9a and/or holes l9b. The present
invention, therefore, provides arrangement in which the
crimps of the sleeve made by the crimping apparatus will
deform the sleeve into contact with in the region of the
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holes l9c and either holes l9a or l9b (or both) as well
as the grooves 18 are deformed into the conductor slots.
In this way, applicants insure that a significant solid
portion of the sleeve in the region of the holes will be
crimped into the conductor to thereby retain the con-
ductor within the contact sleeve. The contact sleeve is
positioned within the crimping members to insure that a
portion of the crimping members extends into the region
occupied by the grooved portions 18 to further retain the
conductor within the sleeve member. By crimping the
sleeve member 10 within the region of the groove portions
18, the conductor and groove portions 18 cooperate to
additionally prevent external forces from pulling the
conductor out of the sleeve member 10.
FIGURES 3 and 4 illustrate the second (liner) and
third (hood) members 30, 40, respectively, of the three-
piece contact of the present invention. These members
30, 40 are generally similar in structure and function to
the members disclosed in the Three-Piece Contact and
Alternate Three-Piece Contact patents. The structure of
the members 30, 40 are not particularly relevant to the
present invention, except that the present invention has
preferred and alternate embodiments as described in the
Three-Piece Contact and Alternate Three-Piece Contact
patents, respectively Reference should be made thereto
for a fuller understanding of the present invention and
its environment. The liner 30 includes a radial
enlargement 32.
FIGURE 5 shows an initial (partial) assembly of the
contact pieces 10, 30 in the present invention. Wall
portions 11, 31 of the members 10, 30, respectively, are
punched and bent inwardly to form an inspection aperture
50.
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FIGURE 6 shows a cross-sectional view of the
assembly of FIGURE 5. The sleeve 10 and the member 30
are shown, and have the inspection aperture 50 and
indentations 52 shown. The aperture 50 allows a visual
inspection of an inserted conductor to insure its proper
preparation and positioning.
FIGURE 7 shows a top view of the member 30 in the
vicinity of the inspection a]perture 50 and better show
the preferred shape of the aperture.
FIGURE 8 shows a partial cross-sectional view of the
entire assembly of a contact 10 showing the inner sleeve
10, the liner 30 and the hood 40. The hood 40 extends
rearwardly to (and over) the radial enlargement 32.
FIGURE 9 shows an alternate structure for a sleeve
10'. The alternate sleeve 10' has the same general
configuration, to include the grooved portions 18. The
holes l9a', l9b', l9c', however, are uniformly spaced but
do not include a set of holes which is formed (split)
along the seam, by including half on one side, half on
the other. The five set of holes are fully defined in
the material even in its flat state.
FIGURE 10 shows a second alternate structure for a
sleeve 10", including 18 holes arranged in three axial
rows l9a", l9b", l9c" of six holes spaced radially around
the sleeve.
While a preferred embodiment of the present inven-
tion has been disclosed with some particularity, it will
be apparent to those skilled in the art that changes may
be made to the present preferred embodiment without
departing from the spirit of the present invention. In
some instances, certain features of the present invention
may be used to advantage without the corresponding use of
other features. For example, ~he number and shape of
holes is not important. Instead of a pair of closely
spaced holes in the rear with a spaced hole forwardly ~in
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each radial set~, the pair of holes could be forwardly,
with the single hole rearwardly (in each radial set).
The grooves can be between the sets of holes, or overlap
one of both sets. Additionally, the grooved portions
need neither be continuous nor extend completely cir-
cumferentially around the body. Accordingly, it is
intended that the illustrative and descriptive materials
herein be used merely to illust:rate the principles of the
present invention and not to limit the scope thereof
which is described solely by the appended claims.
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