High amperage electrical connectors

A hermaphroditic electrical connector, preferably for use in high amperage applications, is disclosed. The connector comprises two substantially identically configured terminal elements adapted to be coupled together. Each of the terminal elements includes a conductive body, an elongated spring member and an open cup adapted to receive a portion of the elongated spring member and the conductive body of the other of the terminal elements when the terminal elements are coupled together.

BACKGROUND OF THE INVENTION 
The present invention relates to electrical connector systems. More 
particularly, the invention relates to hermaphroditic electrical connector 
systems for use in heavy duty, high amperage applications. 
Electrical connector systems are used extensively in many applications. One 
particularly important application involves making an electrical 
connection in which a relatively large amount of electrical current, for 
example, at least about 100 amperes, flows through the connector, such as 
in heavy duty, that is relatively high voltage, situations. Care must be 
taken in these applications to avoid incomplete and/or inefficient 
coupling of the connector components and to avoid excessive temperature 
increases as the current is flowing through the connector. Also, it is 
important that the electrical resistance across such connectors be 
controlled, for example, at a relatively low level. 
One example of an application for a heavy duty, high amperage electrical 
connector system is as a fire wall connector between a jet engine and an 
auxiliary power unit on an airplane. Conventional connector systems 
involve coupled male/female components, which can provide for only 
relatively limited conductive contact surface. Excessive connector 
temperature build up can result and ultimately lead to a permanent welding 
of the connector components. The subsequent heat/temperature rise can 
cause a catastrophic electrical failure within the connector, which would 
have a substantial adverse impact on the overall system, for example, the 
airplane, in which the connector is employed. 
An electrical connector should be useful to provide a safe and effective 
electrical connection even with one of the connector components being 
"hot", i.e., having a substantial electrical potential. In many instances 
in the past, this has not been possible in that the initial contact 
between the "hot" connector component and the other connector component 
resulted in an excessive electrical load being placed on the points of 
contact between the connector components so that there was substantial 
risk of a shorting out of or other damage to the connector system. 
A new connector system, particularly a high amperage electrical connector 
system, which reduces the adverse impact of, or even substantially avoids, 
these problems would be advantageous. 
SUMMARY OF THE INVENTION 
New electrical connector systems have been discovered. These electrical 
connectors are particularly applicable for heavy duty, high amperage 
applications, and provide for a very effective and efficient electrical 
connection even when the amount of current flowing is at least about 100 
amps or amperes, preferably at least about 250 amps and still more 
preferably at least about 300 amps. The present connector components 
provide substantial contact surface so that the temperature rise as a 
result of current flow is effectively controlled. In addition, highly 
effective initial contact between the connector components is provided. 
This controls the heat initially generated at the connector and allows the 
connector to be safely joined while one of the components is "hot". 
Further, the present connectors are preferably structured so that as the 
temperature increases in the coupled connector, the force coupling the 
connector components is also increased. 
One important feature of the preferred connectors of the present invention 
is that the components of such connectors are structured so that as the 
temperature in the coupled connector increases, the electrical resistance 
across the connector is reduced. This feature reduces the electrical 
losses across the connector, as well as aiding in controlling the 
temperature in the connector. 
Each of the advantages of the present connectors is particularly beneficial 
when heavy duty, high amperage loads are involved. 
In one broad aspect, the present electrical connectors comprise two 
substantially identically configured terminal elements adapted to be 
coupled together to allow electrical current to flow from one of the 
terminal elements to the other of the terminal elements. These terminal 
elements, because they are substantially identically configured, may be 
considered hermaphroditic terminal elements, and the coupled terminal 
elements or coupled electrical connector may be considered a 
hermaphroditic electrical connector. 
Each of the two terminal elements includes a conductive body having a 
distal end portion and a proximal end portion, is joined to or otherwise 
in electrical communication with one or more electric wires and/or cables, 
and includes a substantially straight or flat surface extending from the 
proximal end portion toward the distal end portion. This substantially 
flat surface, which preferably has a length equal to at least about 20% 
and more preferably at least about 40% of the length of the entire 
conductive body, is adapted to face, and preferably to come in contact in 
at least one area with, the substantially flat surface of the other of the 
terminal elements when the terminal elements are coupled together. A 
conductive, elongated spring member is provided, and is carried by the 
conductive body, preferably on or near a surface substantially opposite 
the substantially flat surface noted above. This elongated spring element 
preferably extends from the proximal end portion to the distal end portion 
of the conductive body. 
An open cup, defined by the proximal end portion of the conductive body and 
the substantially flat surface of the conductive body, is adapted to 
receive the distal end portion and a portion of the elongated spring 
member of the other of the terminal elements when the terminal elements 
are coupled together. The open cup preferably is partially defined by an 
angled surface of the proximal end portion of the conductive body which is 
spaced apart from the substantially flat surface of the conductive body. 
This angled surface angles away from the substantially flat surface, more 
preferably at an angle in the range of about 5.degree. to about 
30.degree., in the direction toward the distal end portion of the 
conductive body. The open cup is more preferably partially defined by an 
end surface located between the substantially flat surface and the angled 
surface, which end surface may be advantageously located substantially 
perpendicular to the substantially flat surface. The configuration of the 
open cup, and especially the preferred and more preferred embodiments of 
the open cup, is preferably such as to facilitate a more strong or more 
secure coupling of the terminal elements as the temperature increases 
and/or reduced connector electrical resistance as the temperature of the 
coupled connector increases. 
As noted above, the present connector systems are preferably structured so 
that the electrical resistance of the coupled together terminal elements 
is reduced with increasing temperatures, more preferably with increasing 
temperatures in the range of about 20.degree. C. to about 180.degree. C. 
The conductive body of the present terminal elements provides a main or 
primary electrical contact when the terminal elements are fully coupled 
together. 
In one embodiment, the distal end portion of the conductive body is at 
least generally tapered, preferably from large to small, toward the distal 
end of the conductive body. Such tapering facilitates maintaining the 
terminal elements coupled together and further acts to reduce heat 
build-up in connector. 
The conductive body comprises an electrically conductive material, in 
particular a metallic material, such as a copper alloy. Examples of useful 
materials which may be included in the conductive body are 
beryllium/copper alloy, brass, copper itself (drawn copper), bronze, 
stainless steel, and the like. Of these materials, brass is particularly 
useful in that it has very good electrical conductivity and is easy to 
fabricate into the desired configuration of the conductive body. The 
conductive body may be coated or plated with a highly electrically 
conductive material, such as gold and the like metals. 
The elongated spring element preferably includes a distal end in proximity 
to the distal end portion of the conductive body. The conductive body 
preferably includes a groove adapted to receive the elongated spring 
member. The elongated spring member is preferably structured or biased so 
that the distal end of the spring member to be out of contact with the 
distal end portion of the conductive body. 
One important function of the elongated spring member is to provide an 
effective initial contact as the terminal elements are being coupled 
together. Thus, the elongated spring member has sufficient contact area 
with the conductive body of the other terminal element so that a safe and 
effective initial contact is provided, even when one of the terminal 
elements is "hot", thus reducing the risk of localized hot spots, which 
can be detrimental to the structural integrity of the connector system. 
One additional important function of the elongated spring member is to 
provide for secure coupling of the terminal elements. The elongated spring 
member preferably has a different, more preferably decreased, coefficient 
of thermal expansion relative to the conductive body. For example, this 
elongated spring member may comprise a metallic material, such as 
stainless steel, which may be coated or plated with a highly electrically 
conductive material, such as gold and the like metals. The difference in 
the coefficients of thermal expansion of the conductive body and the 
elongated spring member and/or the configuration of the open cup act to at 
least assist in providing a more secure or more strong coupling of the 
terminal elements and/or reduced connector electrical resistance as the 
temperature in the coupled terminal elements increases, for example, 
during use. 
The elongated spring member preferably includes a substantially flat 
portion, an angled portion and an end portion which is substantially 
perpendicular to the longitudinal axis of the elongated spring member. The 
angled portion and substantially perpendicular end portion are located at 
or near the distal end region of the elongated spring member. A plurality 
of finger-like prongs which extend to the distal end of the elongated 
spring member are preferably provided. This configuration of the elongated 
spring member is adapted to provide for very effective contact between the 
elongated spring member and conductive body during use (in a coupled 
connector) and for very effective and secure coupling of the terminal 
elements. 
The elongated spring member has a width which is preferably substantially 
coextensive with, or smaller than, the width of the conductive body. In 
one embodiment, the substantially flat portion of the elongated spring is 
located in proximity to a substantially flat region of the conductive 
body. The substantially flat portion and the substantially flat region are 
positioned to be in contact when the terminal elements are coupled 
together so that there is very effective electrical contact between the 
elongated spring member and the conductive body along a substantial, even 
major (at least about 50%), portion of the length of the elongated spring 
member. 
The elongated spring member is preferably fastened to the conductive body. 
In a particularly useful construction, the elongated spring member 
includes an outwardly extending portion and the conductive body includes a 
groove for receiving the elongated spring member and an indent sized and 
adapted to receive and hold this outwardly extending portion. By 
positioning the elongated spring member in the groove so that the 
outwardly extending portion is received by the indent, the elongated 
spring member is effectively fastened to the conductive body. 
The open cup is preferably configured so that the distal end of the 
elongated spring member of the other terminal element contacts the 
conductive body when the terminal elements are coupled together. 
Each of the present terminal elements preferably includes a cleaning spring 
member adapted to contact the substantially flat surface of the other of 
the terminal elements as the terminal elements are coupled together. In 
this way, the substantially flat surface of the conductive body is 
maintained so as to be very effective and highly conductive. The cleaning 
spring member, which may be made of the same or a different material than 
the elongated spring member, may be secured to the conductive body by 
clips which are located in one or more notches in the conductive body. 
Locating the clips in such notch or notches substantially reduces the risk 
of any dislocation of the cleaning spring member as the terminal elements 
are coupled and uncoupled. 
The present connectors preferably include one or more electrically 
insulating housing components adapted to effectively electrically insulate 
the coupled together terminal elements. In a particularly useful 
configuration, the insulating housing component or components are 
configured to facilitate the coupling together of the terminal elements. 
Housing components made of ceramic and the like electrically insulating 
materials are very effective. 
These and other aspects and advantages of the present invention will be 
apparent in the following detailed description and claims, particularly 
when considered in conjunction with the accompanying drawings in which 
like parts bear like reference numerals.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to the drawings, an embodiment of the present electrical 
connector, shown generally at 10, includes a first coupling assembly 12, 
and a second coupling assembly 14. First coupling assembly 12 holds first 
connector terminal 16, while second coupling assembly 14 holds second 
connector terminal 18, as shown in FIG. 2. 
Included within and held substantially stationary (relative to assembly 12) 
by first coupling assembly 12 are first electrically insulating housing 
elements 20 and 22. Second coupling assembly 14 includes second 
electrically insulating housing elements 24 and 26 and holds these second 
housing elements substantially stationary (relative to assembly 14). Each 
of these housing elements is made of a conventional electrically 
insulating ceramic material. In addition, the housing elements 20, 22, 24 
and 26 include through holes which are sized to allow the first and second 
connector terminals 16 and 18, respectively and the distal ends of first 
and second electrical cables 34 and 36, respectively,, to be placed in 
position, as best shown in FIG. 2. The through hole in first housing 
element 22 is sized so that first cable 34 is held stationary relative to 
element 22. Similarly, the through hole in second housing element 26 is 
sized so that second cable 36 is held stationary relative to element 26. 
An adhesive may be employed to secure first cable 34 in the through hole 
of first housing element 22 and second cable 36 in the through hole of 
second housing element 26. Electrically insulating, thin, polymeric discs 
27 are placed on a number of the surfaces of the housing elements to 
provide a cushion against damage as a result of contact between the 
housing elements. 
First and second connector terminals 16 and 18 are positioned relative to 
each other so that they can be easily coupled. The through holes in the 
housing elements 20, 22, 24 and 26 are positioned off-center (the central 
axis of the through holes is not co-incidental with the central axis of 
the housing elements) in order to facilitate the coupling of the connector 
terminals 16 and 18. Thus, by bringing first and second coupling 
assemblies 12 and 14 together to be coupled, the first and second 
connector terminals 16 and 18 are also properly positioned for coupling. 
In other words, the insulating housing elements 20, 22, 24 and 26, 
together with the coupling assemblies 12 and 14, are sized and structured 
so that the connector terminals 16 and 18 can be coupled in a easy and 
straight forward manner. First housing element 20 and second housing 
element 24 may be considered extended creepage barriers in that such 
elements reduce the risks involved from unintentional sparking as the 
connector terminals are coupled and the coupled connector is used. 
The first coupling assembly 12 and the second coupling assembly 14 are 
structured to hold the first insulating housing elements 20 and 22 and the 
second insulating housing elements 24 and 26, respectively, in place and, 
in addition, can be secured or coupled together after the first connector 
terminal 16 and the second connector terminal 18 have been coupled, for 
example, to provide additional protection for the coupled terminals. The 
functioning of the first and second coupling assemblies 12 and 14 is 
conventional and, therefore, no detailed description of such functioning 
is provided. However, it is clear from the drawings that once the first 
and second connector terminals 16 and 18 are coupled together, as 
described herein, the rotatable coupling element 28 of second coupling 
assembly 14 is threaded onto the forward coupling element 30 of first 
coupling assembly 12. 
The connector 10 can be positioned by fastening plate 32 to the location 
where the connector is to be used, e.g., the firewall between a jet engine 
and an auxiliary power unit in an airplane. In this manner, the connector 
10 is adaptable for use, in much the same way as conventional connectors 
are employed. 
First connector terminal 16 is secured to first electrical cable 34, 
whereas second connector terminal 18 is connected to second electrical 
cable 36. Using the coupled first and second connector terminals 16 and 
18, heavy duty, high amperage loads can be passed from first electrical 
cable 34 to second electrical cable 36, or vice versa. 
First and second connector terminals 16 and 18 are identically structured. 
Therefore, only the first connector terminal 16 is described in detail, it 
being understood that the second connector terminal 18 includes components 
which are structured substantially identically. The components of second 
connector terminal 18 which are referred to herein are identified with the 
same reference numeral as the corresponding components of first connector 
terminal 16, together with an additional "a". To illustrate, the 
conductive body of the first connector terminal 16 is identified by the 
reference numeral "38" and the conductive body of the second connector 
terminal 18 is identified by the reference numeral "38a". 
With specific reference to FIGS. 3, 4, 5 and 6, first connector terminal 16 
includes a conductive body 38, an elongated spring element 40 and a 
cleaning spring member 42. Conductive body 38 is integral with a 
conductive extension 44 which is welded, brazed or otherwise secured to a 
first cable extension 46. The electrically conductive wires 35 within 
first electrical cable 34 are secured in electrical communication with 
first cable extension 46. First electrical cable 34 is crimped or 
otherwise secured to first cable extension 46. In this manner, first 
electrical cable 34 is in electrical communication with first connector 
terminal 16. 
Conductive body 38 is made of brass and is plated with gold. First 
conductive body 38 includes a proximal end portion 48, a distal end 
portion 50 and a substantially flat surface 52 which extends from the 
proximal end portion toward the distal end portion and has a length equal 
to approximately 50% of the length of the conductive body 38 from the 
proximal end 49 of the proximal end portion 48 to the distal end 51 of the 
conductive body. 
The proximal end portion 48 together with the substantially flat surface 52 
define a distally open cup 54 which functions in the coupling of the first 
and second connector terminals 16 and 18, as is described hereinafter. 
Open cup 54 is partially defined by angled surface 55 which is 
substantially opposite substantially flat surface 52, and by end surface 
57 which is substantially perpendicular to substantially flat surface 52. 
The shape of the cup 54 is such as to accommodate the distal end portion 
50 of the conductive body 38 as well as the distal end region 56 of the 
elongated spring element 40. The distal end portion 50 of the conductive 
body 38 is generally tapered, from a larger proximal cross sectional area 
to a generally smaller distal cross sectional area. 
The conductive elongated spring element 40 is made of stainless steel, and 
may be plated with gold, and has a lower or decreased coefficient of 
thermal expansion than does the conductive body 38. Elongated spring 
element 40 is placed in a groove 58 which is located in the proximal end 
portion 48 of conductive body 38 and is partially defined by a surface 60 
which is substantially opposite the flat surface 52. The proximal end 
region 62 of elongated spring element 40 is placed in groove 58. Proximal 
end region 62 includes an outwardly extending flap 64 which is positioned 
to be received in hole 66 located in the proximal end portion 48 of 
conductive body 38. With flap 64 received and held in hole 66, elongated 
spring element 40 is fastened to conductive body 38. 
As shown in FIG. 4, elongated spring element 40 extends along and is in 
contact with surface 60 of conductive body 38 a substantial portion of the 
distance toward the distal end portion 50 of the conductive body. Thus, 
there is effective electrical contact between the elongated spring element 
40 and the conductive body 38 along surface 60. 
The distal end region 56 of elongated spring element 40 is separated from, 
that is not in contact with, the distal end portion of the conductive body 
38 when the first connector terminal 16 is not coupled to the second 
connector terminal 18. This is best shown in FIG. 4. The elongated spring 
element 40 is biased or structured so as to keep the distal end segments 
68 of elongated spring element 40 out of contact with the conductive body 
38 when the first connector terminal 16 is uncoupled, again shown in FIG. 
4. The distal end region 56 of the elongated spring element 40 includes 
angled portions 70, and segments 72 which is substantially perpendicular 
to the longitudinal axis 74 of first connector terminal 16. Distal end 
region 56 of elongated spring element 40 includes a series of three 
finger-like prongs 76, 78 and 80 which include the angled portions 70 and 
the segments 72. These prongs provide an effective biasing action and 
further provide for effective electrical contact, particularly effective 
initial electrical contact as the first and second connector terminals 16 
and 18 are being coupled. 
Cleaning spring member 42 is made of stainless steel plated with gold and 
includes a series of bowed spring elements 82 which extend upwardly from 
the conductive body 38. These bowed spring elements 82 function to contact 
the substantially flat surface 38a of second connector terminal 18 as the 
first and second connector terminals 16 and 18 are being coupled so as to 
clean surface 38a to provide effective electrical conductivity. Cleaning 
spring member 42, which also acts to provide electrical contact surface 
when the first and second terminals 16 and 18 are coupled, includes clips 
84 and 86 which act to fasten cleaning spring 42 to conductive body 38. 
Conductive body 38 is configured to include an indent 88 into which the 
cleaning spring 42 is placed. In addition, conductive body 38 includes a 
series of notches 90 which allow the clips 84 and 86 to fasten the 
cleaning spring member 42 to the conductive body 38 without having the 
clips extend beyond the width of the conductive body 38. This prevents the 
clips 84 and 86 from acting to dislocate the cleaning spring member 42 
when the connector terminals 16 and 18 are being coupled or uncoupled. 
Electrical connector 10 functions as follows. When it is desired to couple 
first connector terminal 16 to second connector terminal 18, the second 
coupling assembly 14 is brought into proximity to the first coupling 
assembly 12. The coupling assemblies 12 and 14 are positioned so that the 
second connector terminal 18 can be coupled to the first connector 16 very 
conveniently. As this coupling occurs, the elongated spring element and 
the distal end portion of the conductive body of each connector terminal 
are received by the open cup of the other connector terminal. The initial 
electrical contact occurs between the elongated spring element and the 
proximal end portion of the conductive body of the other terminal. As the 
coupling is completed, the distal end region of the elongated spring 
element of each connector terminal is made to contact the distal end 
portion of the conductive body of the same connector terminal. As the 
temperature increases in the connector 10 as a result of current flowing 
through the coupled connector, the force holding the elongated spring 
elements and distal end portions of the conductive bodies in the open 
pockets increases, thus making the coupling more secure. This is 
particularly effective when the material used to fabricate the elongated 
spring elements has an increased coefficient of thermal expansion relative 
to the material used to fabricate the conductive bodies. 
With reference to FIG. 7 which shows the two connector terminals coupled 
together, note that the coupled connector 10 includes a number of open 
spaces which provide for effective heat dissipation, without substantially 
detrimentally affecting the quality of the electrical connection. Thus, 
the temperature rise in the coupled connector 10 is preferably lower than 
what might be expected if the connector provided for a complete or solid 
contact with no air spaces or gaps. In addition, the electrical resistance 
across the conductor 10 is controlled, and preferably reduced, with 
increasing temperatures, for example, in the range of about 20.degree. C. 
to about 160.degree. C. Once the first and second connector elements 16 
and 18 have been coupled, the first and second coupling assemblies 12 and 
14 can be joined, in a conventional manner, to provide a completed and 
fully insulated connector system. 
The present connector systems may include, or be associated with, one or 
more other components, such as conventional and well known components, 
which perform one or more functions in and/or provide one or more benefits 
to the present systems. Systems which include one or more of such other 
components are included within the scope of the present invention, 
particularly when such component or components have no substantial or 
undue detrimental effect on the present systems. 
The following non-limiting examples illustrate certain aspects of the 
present invention. 
EXAMPLE 1 
A connector substantially as shown in the drawings was selected for 
testing. The diameter of the proximal end portion of each of the 
conductive bodies was 0.844 inches. The coupled connector terminals were 
run for 60 minutes with a current of 340 amps being passed through the 
connector. The temperature in the connector was measured, as well as the 
electrical resistance across the connector as the result of the current 
flow. 
The connector was run in two modes, one with the connector confined by the 
insulating housing components and the coupling assemblies and one in the 
open air in which the connector was not covered. Results of these tests 
were as follows: 
TABLE I 
______________________________________ 
CONNECTOR 
TEMPERATURE, RESISTANCE, 
.degree.C. MILLIOHMS(10.sup.-3 OHMS) 
MODE START/FINISH START/FINISH 
______________________________________ 
CONFINED 22.9/69.6 1.2/.76 
OPEN AIR* 
21.6/108.2 .33/32 
OPEN AIR* 
21.6/103.7 .33/32 
______________________________________ 
*DUPLICATE RUNS 
These results indicate that the present connector provides for a very 
effective electrical connection, even in high duty, high amperage 
applications. One important feature of the present invention which is 
illustrated in the above example is that the resistance across the 
connector actually is decreased as the temperature in the connector 
increases over time. Also, the temperature increase is relatively low, 
thus making the present connector very effective in applications where 
excessive temperature rise would be detrimental. 
EXAMPLE 2 
The above Example 1 was repeated except that the diameter of the conductive 
body was 0.75 inches. 
Results of these tests are as follows: 
TABLE 2 
______________________________________ 
CONNECTOR 
TEMPERATURE, RESISTANCE, 
.degree.C. MILLIOHMS(10.sup.-3 OHMS) 
MODE START/FINISH START/FINISH 
______________________________________ 
CONFINED 23.0/83.6 1.2/.76 
OPEN AIR* 
21.5/176.4 .33/32 
OPEN AIR* 
21.7/155.8 .36/32 
______________________________________ 
*DUPLICATE RUNS 
These results are substantially consistent with the results indicated in 
Example 1. It should be noted, however, that the temperature increases 
with the smaller connector are larger. This may be the result of reduced 
surface area, which leads to higher localized temperatures within the 
connector. Thus, where appropriate, the larger of two connectors should be 
employed in order to reduce the temperature rise caused by the current 
flow. 
While this invention has been described with respect to various specific 
examples and embodiments, it is to be understood that the invention is not 
limited thereto and that it can be variously practiced within the scope of 
the following claims.