U.S. patent number 3,750,084 [Application Number 05/244,570] was granted by the patent office on 1973-07-31 for high voltage electrical connector lead assembly.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Mervin Amos Gardner.
United States Patent |
3,750,084 |
Gardner |
July 31, 1973 |
HIGH VOLTAGE ELECTRICAL CONNECTOR LEAD ASSEMBLY
Abstract
A high-altitude, high-voltage electrical connector lead assembly
having an externally threaded bushing containing a contact pin, and
an external electrical lead containing a contact pin socket.
Surroundingly engaging, but longitudinally movable upon the
exterior surface of the electrical lead in tightly-fitting fashion
is an internally threaded flexible cap. Upon assembling the
connector assembly, the lead, with its flexible cap, is grasped so
as to insert the end of the lead containing the contact pin socket
into engagement with the bushing contact pin. When the socket and
pin are thus engaged, the flexible cap is then pushed or slid along
the exterior surface of the lead, the flexibility of the cap
permitting its internal threads to flexurally "skip" over the
external threads of the bushing. A resilient O-ring is also
positioned on the external lead, the O-ring being located between
the interior face of the flexible cap and the annular end of the
bushing. Upon completion of the pushing operation performed upon
the cap, the latter may be screw-threaded any remaining distance
along the bushing, this operation serving to axially compress and
radially expand the resilient O-ring, such that the latter forms a
fluid-tight seal.
Inventors: |
Gardner; Mervin Amos
(Highspire, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
22923294 |
Appl.
No.: |
05/244,570 |
Filed: |
April 17, 1972 |
Current U.S.
Class: |
439/277; 439/253;
439/320; 439/278; 439/349 |
Current CPC
Class: |
H01R
13/53 (20130101) |
Current International
Class: |
H01R
13/53 (20060101); H01r 013/54 () |
Field of
Search: |
;339/59-61,69-72,94,89 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Claims
What is claimed as new and desired to be secured by letters patent
of the United States is:
1. A high-altitude, high-voltage electrical connector lead assembly
comprising:
a cylindrical bushing;
a contact pin element disposed in one end of said bushing;
external thread means located upon the other end of said
bushing;
an insulated electrical lead;
a wire conductor disposed in one end of said lead;
a contact pin socket disposed in the other end of said lead for
mating connection with said bushing contact pin element, said
contact pin socket being electrically connected to said lead wire
conductor; and
internally threaded flexible cap means closed at one end and having
a central opening in said closed end for the admission therethrough
of said insulated electrical lead, the flexibility of said cap
means permitting its internal threads to flexurally skip over the
external threads of said bushing when said cap means is forcibly
moved longitundinally on said lead in the direction of said
bushing, whereby said flexible cap means may be pushed or snapped
onto and engaged with, said bushing.
2. A high-altitude, high-voltage electrical connector lead assembly
as set forth in claim 1, wherein the external thread means of said
cylindrical bushing are of a zig-zag configuration, and the
internal thread means of said flexible cap are of a truncated
zig-zag configuration, whereby the particular thread configurations
permit said flexible cap means to be pushed or snapped onto said
cylindrical bushing means but nevertheless prevent said flexible
cap means and said cylindrical bushing from being pulled apart.
3. A high-altitude, high-voltage electrical connector lead assembly
as set forth in claim 1, wherein the external thread means of said
cylindrical bushing and the internal thread means of said flexible
cap means are of corresponding saw-tooth configuration, whereby the
particular thread configurations permit said flexible cap means to
be pushed or snapped onto said cylindrical bushing means but
nevertheless prevent said flexible cap means and said cylindrical
bushing from being pulled apart.
4. A high-altitude, high-voltage electrical connector lead assembly
as set forth in claim 1, wherein said assembly additionally
comprises a resilient O-ring surroundingly engaging said insulated
electrical lead and located between said flexible cap and said
cylindrical bushing, whereby upon assembly, said O-ring will be
axially compressed and radially expanded so as to provide a
fluid-tight seal.
5. A high-altitude, high-voltage electrical connector lead assembly
as set forth in claim 4, wherein said resilient O-ring is movably
disposed upon said insulated electrical lead.
6. A high-altitude, high-voltage electrical connector lead assembly
as set forth in claim 4, wherein said resilient O-ring is
integrally molded with said insulated electrical lead.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to electrical connectors
and more particularly to an improved high-altitude, high-voltage
electrical connector lead assembly for providing a fluid-tight
lead-in to sealed electrical units, such as are employed in high
altitude aircraft, guided missiles, and the like.
The deterioration of the insulation qualities of air caused by the
drop in atmospheric pressure on reaching the higher altitudes now
attainable has rendered inadequate high-voltage lead-in connectors
as have been heretofore employed. For example, studs brought out
through ceramic insulators are subject to arcing from stud to stud
or from the stud to the metal casing, where reliance is placed in
whole or in part upon the dielectric strength of air. Also commonly
employed as high-voltage connectors are plug-type arrangements
where the connection is provided with a surrounding insulating
sleeve, the assembly being enclosed in a supporting metal jacket.
The free path from connection to jacket within such connectors is
subject to arcing at high altitudes, and furthermore, the seal
against oil seepage for hermetically sealed oil-filled units has in
general been found to be unsatisfactory.
One type of high-altitude, high-voltage electrical connector lead
assembly currently being employed, which solves the problems
heretofore noted, is that assembly disclosed in U.S. Pat. No.
2,958,844, to Willard A. Smith et al. which is assigned to the
assignee of the present application. While this assembly has been
generally successfully employed, it however has not been found to
be entirely satisfactory in all commerical applications. One
problem, for example, that has been encountered in the use of the
patented assembly is that because of the threaded method of
connecting the component parts together, that is, the screwing of
the connector cap onto the connector bushing, the external leads,
which are fixed at one end to the end of the connector portion
carrying the cap and at their other end to other electrical
components have a great deal of torque transmitted thereto in the
course of turning the cap to threadably tighten it onto the
bushing, and this problem becomes especially severe in the case
where these leads are very short. This results in the deterioration
of the connections, both between the external leads and the cap
connector portion, as well as between the external leads and the
other electrical components to which the opposite ends of the leads
are connected. In addition, because the cap must be tightly
threaded onto the bushing portion to provide a suitable connection,
the assembly time is quite extensive for putting together the
component parts.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
improved high-altitude, high-voltage electrical connector lead
assembly.
Another object of the present invention is to provide an improved
high-altitude, high-voltage electrical connector lead assembly
which will greatly reduce the assembly time in systems
manufacture.
Still another object of the present invention is to provide an
improved high-altitude, high-voltage electrical connector lead
assembly which will greatly decrease assembly costs in systems
manufacture.
Yet another object of the present invention is to provide an
improved high-altitude, high-voltage electrical connector lead
assembly which will reduce the amount of torque normally
transmitted to connector leads during systems manufacture, and
thereby provide for more reliable connections.
It is a further object of the present invention to provide an
improved high-altitude, high-voltage electrical connector lead
assembly which is quick and easy to assemble, yet is sufficiently
difficult to disassemble so as to prevent the accidental or
inadvertent disconnection of the various components.
A yet further object of the present invention is the provision of
an improved high-altitude, high-voltage electrical connector lead
assembly which will accommodate component parts of different
lengths.
The foregoing objectives are achieved according to this invention
through the provision of a high-altitude, high-voltage electrical
connector lead assembly having a cylindrical bushing portion having
a lead contact pin fixed to one end thereof and extending axially
thereinto, and an external lead adapted to be received in the other
end of the cylindrical bushing and having a lead contact pin
receptacle for frictionally mating with the bushing lead contact
pin. To additionally secure the connection, the bushing portion of
the assembly is externally threaded along an end part of its
length, while the external lead has an internally threaded flexible
cap disposed thereon which is capable of longitudinally sliding
movement upon the exterior surface of the external lead. In
assembling the connector, the external lead, with its
longitudinally slidable cap disposed thereon, is inserted into
mating contact with the bushing lead contact pin, and at the
conclusion of this step, the cap is slid longitudinally along the
exterior surface of the external lead and is subsequently pushed or
snapped with some force onto the bushing portion, the cap flexing
and consequently permitting its internal threads to slide along or
over a portion of the external threads of the bushing. An O-ring
also is positioned on the external lead, being adapted to provide a
fluid seal between the cap interior and the cylindrical bushing
interior upon connection thereof. Thus, when the cap cannot be
pushed or snapped onto the bushing any further, it may subsequently
be threadingly screwed upon the remainder of the threaded portion
of the bushing, this last mentioned threading action serving to
axially compress and radially expand the internally located O-ring
between the closed end of the cap and the annular end of the
cylindrical bushing and about the external lead, respectively, so
that the O-ring consequently acts as a fluid-tight seal.
BRIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features, and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood from the following detailed description
when considered in connection with the accompanying drawings, in
which like reference characters designate like or corresponding
parts throughout the several views, and wherein:
FIG. 1 is an exploded perspective view of a high-altitude,
high-voltage electrical connector lead assembly constructed
according to this invention and showing its cooperative parts;
FIG. 2 is a cross-section view of an assembled high-altitude
high-voltage electrical connector lead assembly as illustrated in
FIG. 1, taken along line 2--2 of FIG. 1;
FIG. 3 is an enlarged fragmentary sectional view of the threaded
cap and bushing of the assembled high-altitude, high-voltage
electrical connector lead assembly as illustrated in FIG. 2;
FIG. 4 is an enlarged fragmentary sectional view of another
embodiment of a threaded cap and bushing which may be employed in
an assembled high-altitude, high-voltage electrical connector lead
assembly as illustrated in FIG. 2; and
FIG. 5 is a side view of another embodiment of an electrical lead
which may be employed in the high-altitude, high-voltage electrical
connector lead assembly as illustrated in FIG. 1, the lead of this
embodiment having a molded O-ring thereon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to FIGS. 1 and
2 thereof, there is shown a high-altitude, high-voltage electrical
connector lead assembly generally indicated by the reference
character 10 comprising a cylindrical bushing 12, an O-ring 14, a
tubular cap 16, and an external lead 18. The cylindrical bushing 12
may be of a suitable dielectric material, preferably of a type
which can be threaded, molded in plastic, and subjected to the wide
range of temperatures encountered in high-altitude applications and
bonding operations, such as for example, soldering, without
cracking, such as a laminated phenolic-base resin, steatite ceramic
or the like. The dielectric material selected however, will no
doubt depend to some extent upon the method employed to seal the
electrical unit. If for example, the unit is to be encased in a
metal can for hermetic sealing, a steatite ceramic, metalized to
provide a surface 20 extending circumferentially of bushing 12 and
which is solderable to the sealed electrical unit casing 22 to
thereby achieve a fluid-tight seal preventing seepage of oil around
the bushing, may be utilized. As an alternative, a laminated
phenolic suffices where the electrical unit is embedded, or potted,
in plastic.
Still referring to FIGS. 1 and 2, it is seen that in order to
facilitate assembly between the component parts of the present
invention, which will be discussed in detail hereinafter, bushing
12 extends through casing 22 of the particular sealed electrical
unit utilized, thereby defining a portion 24 which projects from
the particular sealed electrical unit, and a portion 26 which is
interior of the electrical unit. Projecting portion 24 contains
external threads 28, which may extend almost the full length of
portion 24 or approximately one-half the length of bushing 12, and
an end face 30 which is apertured as at 32. The aperture 32 defines
an entranceway to a recess 34 which extends substantially over the
entire length of the bushing 12, the recess 34 being terminated by
an end face 36 of the interior portion 26 of bushing 12.
Inserted within end face 36 and located along the longitudinal axis
of bushing 12 is a plug 38, which may be rigidly maintained or
secured within an aperture 40 in the end plate 36, as for example,
by soldering or brazing. Plug 38 has at one end a contact pin 42
which extends axially into the recess 34 of bushing 12, and has at
the other end an ear 44 which projects axially externally of the
bushing 12 and facilitates the attachment of other electrical
leads, not shown, extending from other electrical components
situated internally of the sealed electrical unit.
Still referring to FIGS. 1 and 2, the external lead 18 shown
therein is composed of an insulated wire conductor portion 46, and
an elongate substantially rigid insulating sheath portion 48, which
surroundingly encapsulates wire 46. Wire portion 46 thus enters the
rigid sheath portion 48 through one end of an axial cylindrical
opening 54 extending through the sheath, and the other end of the
through opening defines an entranceway to a contact pin socket 60
disposed therein and being of such diameter as to form a friction
fit with bushing contact pin 42. The contact pin socket 60 and the
conductor of lead wire 46 are electrically connected within the
through opening 54 via a solder well 62 disposed therein.
It will be noted that the rigid insulation sheath 48 may be
encapsulated over the wire core 46 by any suitable method according
to the type of materials employed. For example, typical insulating
materials utilized for high voltage leads are silicone-rubber or
natural rubber compositions which expand upon soaking in temporary
liquid plasticizers, such as the aromatic liquids toluene, benzene,
or their derivatives. Accordingly, after stripping the end of the
wire 46 of its insulation to expose the wire conductor, the
conductor is connected to the contact pin socket 60, for example,
by having the latter crimped thereon, and the insulating sheath,
which may be a silicone-rubber composition as described herein, is
soaked in toluene, and is pulled over the connection between the
conductor of wire 46 and the socket 60, extending beyond the
adjacent insulative covering of wire 46 in one direction and
terminating at the end of socket 60 in the other direction.
Thereafter, upon evaporation of the toluene, the insulation
composition shrinks to its original diameter into tight engagement
with the wire conductor, the socket, and the insulative covering of
the wire to provide a rigid sheath. If desired, the stripped
conductor and socket may be soldered before covering with the
sheath 48 to provide a solder well designated at 62.
In connection with the aforementioned, it should also be noted that
to assure maximum protection against arcing, it is preferred that
bushing 12 be filled as completely as possible with dielectric
materials encompassing the metallic elements of the contact
assembly to rid the assembly of residual air gaps. Accordingly, the
inside diameter of the bushing 12, or of recess 34 is only slightly
larger than the outside diameter of the rigid lead insulation
sheath 48, being sufficient just to admit lead 18 internally of
bushing 12 without difficulty, with the result being that
substantially all of the space within the bushing 12 is occupied by
dielectric material.
Finally, to secure together the component parts of the lead
assembly of the present invention as will be discussed more fully
hereinafter, the tubular dielectric cap 16 is provided, being
internally threaded at 68 for cooperation with external threads 28
of bushing 12 and having an end wall portion defining a central
aperture 70, and being composed of an appropriate phenolic resin,
such as, for example, low density polyethylene, so as to be
sufficiently resilient and flexible for a purpose more fully
discussed hereinafter. In conjunction with cap 16, the resilient
O-ring 14 is designed with a diameter so as to enable its being
seated within cap 16 against the end wall thereof and also so as to
be in tight surrounding engagement with insulation sheath 48 of
lead 18. Similarly, the central aperture 70 in cap 16 is of such
diameter that it too affords a tight fit between lead insulation
sheath 48 and the cap. To facilitate manipulation of cap 16,
longitudinal projecting ribs 72 are provided upon the outer
peripheral surface 74 thereof.
With particular reference to FIGS. 1 and 2, the assembly of the
electrical connector of the present invention will be apparent.
With bushing 12 encased within electrical unit wall 22 and
protruding therefrom, flexible cap 16 is flexurally fitted upon
external rigid lead sheath 48, and a similar operation is performed
with respect to O-ring 14 and sheath 48, the O-ring 14 and cap 16
being positioned relative to the sheath 48 as shown in the dotted
line position of FIG. 2.
To assemble the connector, the subassembly composed of lead 18, cap
16, and O-ring 14, is grasped by means of rigid sheath 48, whereby
the end of the sheath portion 48 is inserted within bushing 12, so
that lead contact pin socket 60 is axially aligned with bushing
contact pin 42 and makes frictional contact therewith, the
longitudinal insertion of lead 18 within bushing 12 in the
direction of the arrow A being terminated upon the abutment of the
rigid lead sheath end face with the interior face of bushing end
plate 36. It will be noted at this point that cap 16 and O-ring 14
are still in the dotted line positions relative to lead sheath
48.
Upon complete insertion of rigid lead sheath 48 within bushing 12,
as determined by the respective abutment of the end faces thereof,
as discussed heretofore, final securement of the component parts of
the assembly can now take place. In accordance with such operation,
the flexible cap 16 and the O-ring 14 are slid along the exterior
surface of rigid lead sheath 48 in the direction of arrow A. With
reference to FIGS. 2, 3, and 4, it will be seen that upon sliding
flexible cap 16 and O-ring 14 as heretofore mentioned, the internal
threads 68 of flexible cap 16 will encounter external threads 28 of
bushing 12. Due to the flexibility of cap 16, and the particular
contour or configuration of the relative threads, forcibly pushing
the cap at this time will enable the flexible cap 16 to be moved
along and over bushing 12, each thread 68 of cap 16 flexurally
"skipping" over the corresponding threads 28 of bushing 12. It can
therefore be appreciated that a quick, pushing motion in the
direction of arrow A will cause cap 16 to be snapped onto the
bushing 12. Forward progress of the cap relative to bushing 12 will
usually be halted before its limit of threaded travel is completed.
Cap 16 may then be screw-threaded relative to bushing 12 for
engaging the remaining threads, such action respectively axially
compressing and radially expanding O-ring 14 between the inside
face 76 of cap 16 and the annular end surface 30 of the bushing 12
and between the inside wall of the cap and the sheath 48. The
O-ring 14 may be formed of rubber or other similar material, such
that the resulting action just described upon O-ring 14 provides
the assembly with a fluid-tight seal.
Referring now to FIGS. 3 and 4, two embodiments of thread
configuration for the cap and bushing are illustrated. FIG. 3
discloses external threads 28 of bushing 12 being of the
conventional zig-zag design, whereas the internal threads 68 of
flexible cap 16 are of a truncated zig-zag design, the respective
sides of which, 78 and 80, include the same angle with respect to a
plane passing through the longitudinal axis of the assembly. In
FIG. 4, however, the threads of each part are seen to be of
saw-tooth configuration.
Examination of FIGS. 3 and 4, in conjunction with the above
disclosure, will make it apparent that, due to the specific thread
configurations, and by an appreciation of the force magnitudes
involved in the pushing and pulling operations, although the
flexible cap 16 may be snapped partway onto bushing 12, it cannot
be snapped or pulled off, but on the contrary, these respective
parts can only be separated by a reverse screw-threading operation.
Hence, although the connector may be quite easily and quickly
assembled, it is difficult to disassemble it unintentionally.
Consequently, more reliable connections result, and inadvertent and
accidental disconnections cannot occur.
Referring now to FIG. 5, a second embodiment of the external lead
is disclosed, this lead 18', being similar to lead 18, is composed
of an insulated wire 46 and a rigid insulation sheath 48, but an
additional feature of this lead however, is that an O-ring 82 is
integrally molded with the insulation sheath 48. Although this
particular lead embodiment can sufficiently and effectively perform
its respective functions within the lead assembly of the present
invention, it will be appreciated that with this embodiment, the
relative lengths of the various components, i.e., of the bushing
receptacle and the external lead, especially its cap portion, are
fixed, due to the fact that upon ultimately assembling the lead
assembly, O-ring 82 must be seated in abutting relationship to end
face 30 of bushing 12 while the cap must be simultaneously able to
reach the threaded periphery of the bushing 12, such that standard
receptacles can be used and the lead may be plugged in or be
readily repairable in the field with a replacement piece.
With the non-molded O-ring embodiment of FIGS. 1 and 2, on the
other hand, a loose O-ring has the advantage of accomodating
different lengths of component parts, and thus of being readily
field repairable even in the absence of a standard-size piece.
Thus, it may be seen that the high-altitude, high-voltage
electrical connector lead assembly of the present invention has
important advantages over the known prior art structures in that
the connector may be rapidly assembled, the assembly process
through its provision of a snap-on cap consequently eliminating
much of the threading step that heretofore results in turning the
wire 46, which is connected at its other end and, thereby
preventing the introduction of torque at the other lead end
connections, and facilitating more rapid and more reliable
connector assemblies.
Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is to be
understood, therefore, that within the scope of the appended claims
the present invention may be practiced otherwise than as
specifically described herein. Accordingly,
* * * * *