U.S. patent number 3,812,448 [Application Number 05/309,514] was granted by the patent office on 1974-05-21 for electrical connector.
This patent grant is currently assigned to Thomas & Betts Corporation. Invention is credited to Louis F. Haitmanek.
United States Patent |
3,812,448 |
Haitmanek |
May 21, 1974 |
ELECTRICAL CONNECTOR
Abstract
An electrical connector having an internal tooth structure and a
selectively grooved conductor engaging inner surface therebetween
providing reduced thickness web portions responsive to the
expansion and contraction of an enclosed conductor to prevent
relative movement at the interface between the conductor and the
connector thereby maintaining secure mechanical and electrical
contact therebetween under even extreme conditions of temperature
cycling.
Inventors: |
Haitmanek; Louis F. (Florham
Park, NJ) |
Assignee: |
Thomas & Betts Corporation
(Elizabeth, NJ)
|
Family
ID: |
23198534 |
Appl.
No.: |
05/309,514 |
Filed: |
November 24, 1972 |
Current U.S.
Class: |
439/421; 174/84C;
439/882 |
Current CPC
Class: |
H01R
4/2495 (20130101); H01R 4/18 (20130101); H01R
4/184 (20130101) |
Current International
Class: |
H01R
4/10 (20060101); H01R 4/24 (20060101); H01R
4/18 (20060101); H01r 011/20 (); H01r 011/08 () |
Field of
Search: |
;24/16R,16PB,2W,22,23W
;339/95-99,223,276 ;174/84C,94R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gay; Bobby R.
Assistant Examiner: Staab; Lawrence J.
Attorney, Agent or Firm: Teschner; David Woldman; Jesse
Claims
The embodiments of the invention in which an exclusive property
or
1. An electrical connector comprising: a base member formed from
electrically conducting ductile metallic material and having an
inner surface, an outer surface, and a first thickness defined by
the spacing between said inner surface and said outer surface; a
series of generally elongate selectively spaced grooved portions
arranged in a predetermined pattern within said base member inner
surface, the bottom of said grooved portions extending below said
base member inner surface a predetermined depth and the sidewalls
of said grooved portions extending upwardly normal to the plane of
said inner surface, the spacing between the bottom of said grooved
portions and said base member outer surface defining a second
thickness thereat, said second thickness being less than said first
thickness; a series of selectively deformable teeth extending
outwardly from said base member inner surface a predetermined
distance, said teeth being arranged in pairs, each tooth of said
pair extending along substantially the length of and adjacent to an
associated one of the pair of opposing sidewalls of an associated
one of said grooved portions, said teeth having convex exterior
surfaces defining the sides thereof, said exterior surfaces
converging to a sharp edge defining the top of said teeth, the
exterior convex surface of each of said teeth adjacent a
corresponding grooved portion communicating smoothly with an
adjacent sidewall of said grooved portion to provide a continuous
surface thereat; the regions of said base member defined by said
second thickness providing expandable web portions intermediate
said base member first thickness regions, said base member thereby
being longitudinally responsive to the expansion and contraction of
a conductor disposed therewithin upon the selective closure of said
base member about such conductor so as to form a
2. An electrical connector as defined in claim 1 wherein said teeth
extend generally transversely across said base member inner surface
generally
3. An electrical connector as defined in claim 1 wherein the height
of said teeth above said base member inner surface is at least
equal to the depth of the bottom of said grooved portions below
said base member inner
4. An electrical connector as defined in claim 3 wherein said teeth
are all of equal height and have symmetrical convex exterior
surfaces defining the
5. An electrical connector as defined in claim 1 wherein said teeth
are all of equal height and have symmetrical convex exterior
surfaces defining the
6. An electrical connector as defined in claim 1 wherein the
spacing between adjacent pairs of said teeth is greater than the
spacing between
7. An electrical connector as defined in claim 1 wherein said teeth
are
8. An electrical connector as defined in claim 1 wherein said teeth
are
9. An electrical connector as defined in claim 1 further comprising
means
10. An electrical connector as defined in claim 1 wherein the
bottom surface of each of said grooved portions is planarly
disposed generally
11. An electrical connector as defined in claim 1 wherein said base
member outer surface has a series of generally elongate recesses
disposed therein, said recesses each extending in generally
parallel opposed relationship with respect to a corresponding one
of said base member inner
12. An electrical connector as defined in claim 11 wherein each of
said teeth have symmetrical convex exterior surfaces defining said
sides thereof.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to the field of connecting devices and
principally to an improved electrical connector.
2. Description of the Prior Art
In the field of electrical connecting devices having generally
elongate ridge-like tooth forms as exemplified, for example, in
U.S. Pat. No. 3,293,355 issued Dec. 20, 1966 to Gropp et al., U.S.
Pat. No. 3,355,698 issued Nov. 28, 1967 to Keller, and U.S. Pat.
No. 3,436,946 issued Apr. 8, 1969 to Gropp et al., the device was
generally fabricated of copper or copper alloy material designed
principally for attachment to copper conductors having a similar
co-efficient of expansion. In the event the connection was
subjected to extremes of temperature cycling both the connector and
the conductor encased therewithin would expand or contract in like
manner thereby generally avoiding relative motion or displacement
therebetween which motion would tend to disrupt or destroy the
integrity of the connection. Such devices were, however, found to
be generally unsatisfactory for use, for example, with a conductor
having a coefficient of expansion sufficiently different from that
of the connector as to cause relative motion between the connector
and the conductor upon temperature cycling of the connection as,
for example, where a copper or copper alloy connector was employed
with an aluminum conductor, thereby destroying the established
interface contact with a consequent deterioration of the
connection. Attempts to solve this problem by providing, for
example, an aluminum connector for use with aluminum conductor were
generally unsatisfactory since such a connector not only lacked the
requisite resiliency and deformability necessary for such
applications, but was also more expensive to manufacture and was
additionally limited in use to applications involving only aluminum
conductors. It should also be noted that because of the higher
resistivity of aluminum material as compared with copper or copper
alloy material, a connector formed from the former must, of course,
be commensurately larger and generally more expensive, than a
comparable copper or copper alloy connector having the same
electrical rating.
SUMMARY OF THE INVENTION
The invention overcomes the limitations and difficulties noted
above with respect to prior art devices by providing an electrical
connector suitable for use with a conductor having either a similar
or substantially different coefficient of expansion, thus providing
a means for establishing a more secure, reliable, and economical
electrical connection between, for example, a copper or copper
alloy connector and an aluminum conductor than was possible with
such prior art devices. The device comprises a series of generally
parallel protruding elongate teeth extending generally transversely
across the inner surface of a crimpably deformable base member.
Intermediate each selective pair of teeth is a selectively
proportioned grooved portion defining a region of predetermined
thickness somewhat less than the major thickness of the base
member, thereby providing expandable web-like portions spaced one
from another by ungrooved regions having a thickness essentially
equal to the base member major thickness, the grooved portions
being readily responsive to the expansion and contraction of a
conductor about which the base member is crimped. The established
interface contact is thereby securely maintained upon the thermal
cycling of the connection, thus insuring a superior electrical and
mechanical connection therebetween. The elongate teeth extending on
either side of the grooved portions terminate in a relatively sharp
edge adapted to pierce the outer surface of the conductor or the
insulation disposed thereabout and penetrate the interior of the
conductor, each pair of said teeth being disposed in such manner as
to convergingly deform somewhat upon penetration of the conductor
to engage the conductor interior in hook-like fashion to increase
the engagement therebetween. The grooved portions of the connector
also serve to provide a pocket adapted to accommodate a portion of
the conductor extruded thereinto during the crimping operation and
subsequent expansion of the conductor. The teeth may be provided
with either arcuate or generally planar sides or a combination
thereof to control the direction of deflection and to insure
adequate conductor penetration and separation of the insulation
disposed about an insulated conductor. It is therefore an object of
this invention to provide an improved electrical connector.
It is another object of this invention to provide an electrical
connection between a connector and a conductor having different
coefficients of linear expansion.
It is a further object of this invention to provide a means for
preserving the integrity of an electrical connection established
between elements having different coefficients of linear expansion
and exposed to large thermal excursions.
It is a further object of this invention to provide a reliable
connection between a copper or copper alloy connector and an
aluminum conductor.
It is still another object of this invention to provide a
longitudinally expansive electrical connector.
It is still a further object of this invention to provide an
electrical connector having selectively spaced expandable regions
responsive to the forces exerted thereon by an expanding and
contracting conductor engaged therewithin.
Other objects and features of the invention will be pointed out in
the following description and claims and illustrated in the
accompanying drawings which disclose by way of example the
principle of the invention and the best mode contemplated for
carrying it out.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of an electrical connector constructed
in accordance with the concepts of the invention.
FIG. 2 is a fragmentary elevational view, in section, of the device
of FIG. 1 taken along the lines 2--2.
FIG. 3 is a perspective view of the device of FIG. 1 pre-formed
into a generally U-shaped ferrule and having an attaching means
coupled thereto.
FIG. 4 is a front elevational view, partly in section, of the
device of FIG. 1 crimped about an insulated conductor.
FIG. 5 is a fragmentary side elevational view, in section, of a
portion of the device of FIG. 1 in a first stage of engagement with
an insulated conductor.
FIG. 6 is a fragmentary side elevational view, partly in section,
of the device of FIG. 1 in a further stage of engagement with an
insulated conductor.
FIG. 7 is a fragmentary side elevational view, in section, of the
assembly of FIG. 6 after engagement showing the manner of expansion
thereof upon thermal cycling of the connection.
FIG. 8 is a fragmentary side elevational view, in section, of a
portion of a further embodiment of a connector constructed in
accordance with the concepts of the invention.
FIGS. 9 and 10 are fragmentary side elevational views, in section,
of a portion of further embodiments of an electrical connector
constructed in accordance with the concepts of the invention.
Similar elements are given similar reference characters in each of
the respective drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to FIGS. 1 and 2 there is shown an electrical connector
20 constructed in accordance with the concepts of the invention.
Connector 20 comprises a base member 22 having an inner surface 24
within which are formed a series of selectively spaced grooved
portions 26 which, as shown in FIG. 1, extend essentially
transversely across substantially the entire inner surface 24 of
base member 22. Each of the grooved portions 26 extend preferably
the same depth below the inner surface 24 of base member 22, the
particular depth of the grooved portions 26 being controlled or
regulated to provide a predetermined thickness thereat designated
as T.sub.1 in FIG. 2, which, as will be described in more detail
hereafter, functions as an expandable web-like region. The
ungrooved portions of the base member 22 intermediate the grooved
portions 26, and having a thickness designated in FIG. 2 as
T.sub.2, provide relatively rigid regions therebetween. The
expandable web-like regions defined by the grooved portions 26 are
shown in FIG. 2 as encompassing a length 28 bounded by the
ungrooved portions of the base member 22. Protruding outwardly from
the inner surface 24 of base member 22 are a series of preferably
parallel transversely extending teeth 30 arranged in pairs
extending substantially along the entire length of the grooved
portions 26 and bordering the opposing sides thereof. Each tooth
30, as illustrated in FIGS. 1 and 2 comprise generally arcuate
exterior surfaces 32 convergingly disposed to define a relatively
sharp edge 34 which, as will be explained in more detail hereafter,
provides both insulation and oxide piercing means.
As illustrated, one of the surfaces 32 of each tooth 30 is arranged
generally coplanar with the adjacent sidewall of an associated
grooved portion 26, the opposing surface of each tooth 30
terminating at the inner surface 24 of base member 22. With this
arrangement, each of the teeth 30 tend to buckle or deflect towards
one another above an associated grooved portion 26 as they are
forcibly urged into engagement with a conductor, the result of this
tooth deflection being described in more detail hereafter. Other
tooth contours which may be similarly employed are shown, by way of
example, in FIGS. 8 and 9. As illustrated in FIG. 8 one surface of
each tooth is generally planar as at 36, and the other surface is
arcuate as at 38. The embodiment illustrated in FIG. 9 includes a
tooth form having generally converging planar surfaces 40 and 42,
surface 40 communicating with the sidewall of an associated grooved
portion 26 to form an extending plane thereat similar to the
arrangement shown in FIG. 8, while the opposing surface 42 is
disposed at a generally oblique angle with respect to a plane
normal to the plane of the inner surface 24 of base member 22 to
form a saw-tooth type configuration. Although the teeth may extend
uninterruptedly across substantially the entire inner surface 24 of
base member 22 a series of longitudinally extending slots or
channels 43 as shown in FIG. 1 may be provided to permit the base
member 22 to be more readily pre-formed or folded therealong to
provide, for example, a generally U-shaped base member 45, as shown
in FIG. 3. The height of teeth 30 above the inner surface 24 of
base member 22 indicated in FIG. 2 as T.sub.3 is selected to
provide predetermined penetration into the conductive portion of
either an insulated or non-insulated conductor. For example, where
the connector 20 is employed for preselective piercing of a
non-insulated conductor or the bared portion of an insulated
conductor, the tooth height T.sub.3 may accordingly, be less than
that designed for use with an insulated conductor where, in the
latter case, the teeth 30 are required to pierce through the outer
insulative covering and then through to a similar depth within the
conductive portion of the conductor. As will be explained in more
detail hereafter, the grooved portions 26 also function to provide
expansion pockets for accepting a portion of the conductor as the
base member 22 is crimped thereto and during expansion of the
conductor.
Turning now to FIGS. 4, 5 and 6, there is shown, in detail, the
various stages in the assembly of connector 20 to a conductor such
as 44. In FIG. 4, for example, there is shown, in cross-section,
the base member 22 crimped about the insulated conductor 44, the
teeth 30 of the base member 22 having been suitably proportioned to
pierce through the insulated covering 46 of the conductor 44 and
penetrate the conductive portion thereof to a predetermined depth,
which may be in the order of from 5 to 50 percent of the diameter
of the conductor. During the first stage of the crimping operation,
which is more clearly illustrated in FIG. 5, the teeth 30 are
caused to pierce through the insulative covering 46 and penetrate
the conductive portion of the conductor 44 substantially as shown,
the teeth 30 being substantially undeflected during this stage of
the procedure. However, as an increased crimping force is applied
to the assembly, the teeth 30, as illustrated in FIG. 6, are caused
to deflect under the increased crimping pressure and fold inwardly
towards one another over the grooved portion 26 therebetween. A
portion 48 of the conductor 44 intermediate each pair of inwardly
extending teeth 30 is thereby substantially extruded into the
channel formed by the grooved portions 26 and lockingly entrapped
therein. The conductive portion of the conductor 44 is thus engaged
by a substantial portion of that surface of the tooth 30 opposite
the side adjacent to the grooved portion 26 and also by the other
surface of the tooth 30 communicating with the grooved portion 26,
together with the sides of the grooved portion 26 adjacent thereto.
It is thus seen that a substantially greater area of contact is
provided between the teeth 30 and the conductive portion of the
conductor 44 than that provided solely by the tooth surfaces
themselves. Where the conductor 44 and the connector 20 are formed
from materials having a similar coefficient of expansion, the
connection illustrated in FIG. 6 will provide a superior electrical
and mechanical connection between such members under even
relatively severe thermal excursions because of their generally
similar rates of expansion and contraction in response to
temperature variations. Because of its unique configuration, the
connector 20 may be employed with equal efficacy where its
coefficient of expansion is substantially different than that of
the conductor to which it is to be attached. For example, the
conductor 44 may be formed from aluminum or similar material, and
the connector 20 formed from copper or copper alloy material, the
difference in the coefficient of expansion between the two
materials being in the order of approximately 1.5 to 1, aluminum
having approximately a 50 percent greater coefficient of expansion
than copper. Thus, upon the temperature cycling of such a
connection, the aluminum conductor will tend to expand or contract
both radially and longitudinally within the connector to a greater
extent than the copper connector. Referring to FIG. 7, the
conductor 44 will tend to expand longitudinally as indicated by
arrows 50, and 50' and radially outwardly generally as indicated by
arrows 52, and 52'. Since the expansion of the conductor 44 is
greater than the expansion of the connector 20, a longitudinally
directed force will be applied to the connector 20 tending to
elongate the connector longitudinally in response to the expansion
of the conductor 44. The web-like expandable regions indicated
generally at 28, having a thickness somewhat less than the major
thickness of the connector base member 22, will tend to stretch and
thin out, as illustrated, within its elastic limit in response to
the forces generated by the expanding conductor 44, thereby
maintaining intimate engagement between the conductor 44 and the
base member 22, despite their different rates of expansion. The
radial expansion of the conductor 44 is accommodated, to a large
measure, by reason of the chambers formed by the grooved portions
26 wherein the extruded portions 48 of conductor 44 are permitted
to expand freely therewithin, thereby substantially reducing those
forces tending to radially enlarge the connector and disturb the
configuration of the original connection. Upon the cooling of the
assembly, the elements thereof will contract in a similar manner to
their original state, thereby providing an unimpaired connection
therebetween. The interity of the joint may thus be preserved
despite repeated cyclings of the assembly, thereby providing a
secure, reliable, and permanent electrical and mechanical
connection between dissimilar metals. The outer surface of the base
member 22 may be recessed as at 54 in FIG. 10, the recesses 54
extending in generally opposed parallel relationship to the grooved
portions 26 formed in the inner surface of the base member to
provide the desired thickness thereat. This arrangement may also be
found useful where it is desired, for example, to provide an
insulative coating such as 56 about the outer surface of the base
member 22, the recesses 54 thereby providing means for retaining
the insulative covering 56 in position thereabout. The embodiment
illustrated in FIG. 10 may also be found particularly useful where
it is desired to reduce the depth of the grooved portion 26 below
the inner surface 24 of the base member 22 while providing a
predetermined web portion thickness T.sub.1. The length of the
expandable web portion regions 28 (FIG. 2) relative to the length
of the ungrooved portions of the base member 22 intermediate each
pair of grooved portions 26 may be readily chosen to provide a
greater or lesser degree of expansion, as necessary or desirable.
For example, where it is desired to provide a relatively high
degree of expansion, the length of the expandable web portion
region 28 may be at least equal to or greater than the length of
the ungrooved portion region indicated generally in FIG. 2 at 58.
Conversely, where less expansion is desired, the length of the
expandable web portion region 28 may be proportioned to be somewhat
less than the length of the ungrooved portion region 58. The
connector 20 may be coupled to a further member such as, for
example, a terminal board or further connector by means of a tongue
portion coupled to the base member 22, such as indicated for
example at 60 in FIG. 3. Although the particular coupling means
illustrated therein is shown as an apertured tongue member, a
forked tongue, tab, or tab receiving receptacle may alternatively
be employed to effect a similar result.
It will of course be appreciated that although other configurations
may be employed, it has been preferable to contour the bottom
surface of the grooved portion 26 to define a generally planar
surface substantially parallel to the inner surface 24 thereof to
provide a generally constant thickness T.sub.1 within the
expandable web portion region 28.
* * * * *