Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
This invention relates to multiaxial cables, connectors, and co-
axial contact assemblies therefor. More particularly, the invention relates
to termination of multiaxial cables, and, especially, to termination of min-
iature cables through contact assemblies usable in multipin electrical con-
nectors and multicable electrical connectors.
In general, coaxial cables are made up of: an inner conductor,
which may be solid, stranded, bala~ced line, etc., made from copper, tin
plated copper, silver plated copper, copper covered steel~ etc.; a dielectric
material which may be solid, foamed, tape, helical wrap, and like from nat-
ural or synthetic elastomers and polymers; an outer conductor (sheath) which
usually is braided copper wire or copper strip, which may be bare or plated,
and more than one braid may be used. The outer conductor is covered by a
protective, electrically insulating jacket which is usually a solid covering
made of synthetic elastomer or polymer.
Triaxial cable adds another dielectric material layer over the first
outer conductor and adds a second outer conductor over the second dielectric
layer. The triaxial cable is protected like a coaxial cable.
All multiaxial cables must be terminated. Most commonly terminat-
ions involve the connection of two cable ends to complete a circuit or, in
effect, lengthen the cable to reach a more distant location. These terminat-
ions involve electrical connectors: which may be for connecting two cables
only, or as a contact assembly be used in conjunction with wire or other
contact assemblies in a multipin or multicable electrical connector.
Coaxial cable because of its complex structure is easily affected
by atmospheric conditions and/or electrical interaction of the different mat-
erials in the sandwich of conductors and dielectric. The protective ]acket,
itself a dielectric5 also has an effect on the electrical interaction. All
these materials have coefficients of expansion and these can be widely differ-
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ent in a giv0n cable. As a result tllc members of the cable have different
length potentials at cable temperatures other than standard temperature.
When the inner conductor is terminated in a pin-socket contact and
the inner dielectric, i.e., the cable dielectric adjacent to the inner con-
ductor is not restrained, temperature changes may cause the inner dielectric
to expand against the inner pin-socket contact, or even flow over and around
the inner pin-socket contact, resulting in undesirable, and even intolerable,
electrical changes at the inner pin-socket contact.
The inner conductor does change length with temperature change,
tending with increasing length to reinforce the disturbance caused by the
inner dielectric length change. When the inner conductors terminated in an
inner pin-socket contact shorten, they try to pull the inner pin-socket con-
tact apart.
It is known to place a crimp sleeve over the tail of the housing,
the outer conductor extending over the tail, the cable dielectric extending
into the housing, and the inner conductor outside of the barrel of the pin
(or socket). The sleeve is crimped to fasten these members and to captivate
the cable dielectric. It has been found that this procedure does not give
satisfactory captivatîon. The dielectric material is not held tightly
enough by the sleeve crimp and the cable dielectric soon shows undesired
axial movement, and disturbances in the electrical state at the inner pin-
socket contact.
It has been found that the effects of the undesired axial movement
of the inner dielectric material can be minimized by a mechanical restraint
applied to the inner pin-socket contact.
SUMMARY OF THE INVENTION
This invention is directed to a contact assembly for terminating
two multiaxial cables, under conditions where the inner pin-socket contact
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`r of said contact assembly is substantially captivated against axial movement.
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The invention provides a coaxial contact assembly for captivating
inner pin-socket electrical contacts, wh;ch contact assembly comprises:
a pin housing and a socket housing for overlapped electrically
conductive joinder;
pin member and socket member located with said corresponding
housi.ngs, for electrical mating;
said pin member and said socket housing having abutting, non-con-
ductive relati.on when in the mated condition;
said pin member and said socket member each having a barrel for
receiving a coaxial cable inner conductor to be terminated within said
contact assembly;
said pin housing and said socket housing each having a barrel port-
ion over which an outer conductor end portion of corresponding coaxials can
be positioned;
dielectric material within each of said pin housing and said socket ::
housing to insulate the respective housing from its corresponding pin or
socket member, said dielectric material extending beyond the corresponding
barrel, beneath the corresponding outer conductor end portion, and forward to
provide abutments at the barrel end of said socket member against forward
axial movement of a cable inner dielectric and backward movement of said
inner pin-socket contact, and to provide abutment for the inner dielectric of
a second cable and to provide dielectric surface at sai.d pin member for afore-
said abutting socket housing-pin member relation; and
ferrule crimp means encircling corresponding: housing barrel,
extended dielectric material, cable inner dielectric and cable inner conduct-
or,
whereby when said cables are in position in the contact assembly,
crimping said ferrules substantially captivates the inner pin-socket contacts
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against axial movement; and
where said housing dielectrics are substantially rigid, insulating
materials with high resistance to cold flow.
The invention will further be descri~ed, by way of example only,
with reference to the accompanying drawing, wherein:
Figures 1, la, and lb form one complete figure which shows one
embodiment of the multiaxial contact assembly of the invention. For clarity
in presentation, a miniature contact assembly was enlarged about 20/1, which
enlargement forced cutting the drawing into three sections along the longi-
lQ tudinal dimension, to meet space limitations for individual sheets.
DESCRIPTION OF A PREFERRED EMBODIMENT
The embodiment as shown is suitable for use in conjunction with a
multipin connector, for example, the multipin connector of Cooper and Howett,
United Sta~es of America Patent No. 4,056,298. ~hen used alone to terminate
two cables, the embodiment needs protection against physical abuse, such as,
a protective encasement, which encasements are welI known in the coaxial con-
nector art.
It is pointed out that the drawing shows the contact assembly in a
partially mated condition. This has been done to provide more space at the
pin-socket contact zone, to show the various members in the zone. As is
self-evident, the contact assembly is brought into abutting relation of the
pin member and the socket housing member, when the pin and socket are fully
mated.
In the figures, the coaxial contact assembly for captivating inner
pin-socket electrical contacts of the invention comprises an electrical socket
assembly 10 (Figures l la) for mating with an electrical pin assembly 70
(Figures la-lb). Socket assembly 10 is also referred to as the male assembly
and pin assembly 70 is also referred to as the female assembly.
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In Figure 1, an end portion of a coaxial cable 14 is shown. Co-
axial cable 14 is made up of inner conductor 18, inner dielectric material 20,
and double braided outer conductor 22 and 24. The protective jacket, not
shown, stops outside the figure. It is to be understood that the coaxial
cable ends are shown to illustrate the utility of the invention, but are not
part of the invention.
Socket assembly 10 comprises ~Figures l-la) electrical socket
member 30 having a pin receiving socket 32 at one end, away from coaxial cable
14, and a barrel 34 at the other end, having a squared rear end 35, for re-
ceiving a portion 36 of the inner conductor of the cable 14, when present.
The entry 38 ~Figure la) of socket 32 is bevelled to ease entrance of the
pin 92. Socket barrel 34 is sized so that the inner conductor portion 36 may
be crimped within the barrel, holding the conductor 36 and improving electric-
al contact.
An electrically conductive socket housing 40 ~Figures l-la) is co-
axially aligned around socket member 30 and has a cylindrical nose portion 42,
which has a relatively squared end 44. The nose portion 42 extends beyond
the entry 38 to socket 32. Socket housing 40 has at its other end a cyl-
indrical barrel ~tail) portion 46. Barrel 46 can be inserted underneath an
end portion 48 of outer conductor braid 22 to make electrical contact there-
with.
Dielectric materials 50 ~Figures l-la) and 110 ~Figures la-lb) are
substantially rigid, insulating materials with high resistance to cold flow,
such as, polyester, polyamide, and polyimide.
Dielectric material 50 is positioned in socket assembly lQ between
socket member 30 and socket housing 40 to electrically insulate these from
each other and, also, socket member 30 from outer conductor 48; dielectric 50
essentially fills aforesaid space. Dielectric 50 extends back beyond socket
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housing tail portion 46 a substantial distance underneath outer conductor 48,
when this is present, so as to underlie a ferrule 60. Dielectric 50 may be
in one piece, but normally will consist of more than one piece for greater
ease of manufacture and installation. In general, the number of pieces in
dielectric 50 is determined by the configuration of the cavity between socket
member 30 and socket housing 40. The individual pieces may be formed from
the same type of material, or from different mater;als in the defined class
of materials.
Herein, dielectric sa is fitted as two pieces 52 and 54 ~Figures 1-
la). Piece 52 extends out to socket housing end 44 to insulate electricallynose portion 42 from electrical pin 92, when pin 92 and socket 32 are mated.
Dielectric piece 54 extends roughly from the outer end 61 of
ferrule 60, at the approximate level of the outer surface of tail portion 46,
underneath ferrule 60, end portion 48 of braid 22, tail portion 46 and for-
ward until it abuts rear end 35 of socket barrel 34 at flat end 56. Herein,
a shoulder 55 of piece 54 abuts against end 47 of barrel 46, which shoulder
55 restrains piece 54 from movement toward socket barrel 34. Piece 54 is
provided with another shoulder 57 against which the inner end of cable inner
dielectric 62 can abut in forward axial movement thereof. Ends 56, 57 and
the dielectric therebet~een bar the inner dielectric 62 from further move-
ment toward the inner pin-socket contact zone and thereby minimize electrical
disturbances caused by cable inner dielectric movement.
Socket assembly 10 includes a conductive ferrule crimp means 60.
~errule 60 encircles: socket housing barrel (tail) portion 46, socket
assembly dielectric material 54, end portion 48 of outer conductor 22, cable
inner dielectric 62, and that portion of cable inner conductor roughly under
ferrule 60. Ferrule 60 is of metal capable of being crimped to fasten togeth-
er ~1~ the ferrule, the encircled tail portion, and outer conductor; and (2)
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the ferrule, outer conductor, and dielectric 54 extending beyond the tail
portion. The crimp (2~ restrains the inner pin-socket contact against
rearward pull of inner dielectric and inner conductor.
An end portion of a second coaxial cable 74 ;s shown in Figure lb.
Cable 74 is made of inner conductor 76, inner dielectric material 78, and a
double braid outer conductor 80 and 82. The protective jacket is outside the
figure.
Pin assembly 70 as set forth in Figures la-lb comprises an electric-
al pin member 90 having a pin 92 at one end, away from cable 74, and a barrel
94 at the other end for receiving a portion 96 of the inner conductor of
cable 74. Pin barrel 94 is sized so that inner conductor portion 96 can be
crimped therein, holding inner conductor 96 and improving electrical contact.
An electrically conductive pin housing 100 (Figures la-lb) is co-
axially aligned around pin member 90 and has a cylindrical taped nose portion
102 having forward end 103, end 103 being divided into a plurality of spring
fingers for improving electrical contact with socket nose portion 42. Pin
housing 100 has at its other end a cylindrical barrel (tail) portion 106,
for insertion underneath an end portion 108 of outer conductor braid 80 and to
make electrical contact therewith.
Dielectric material 110 (Figures la-lb) is positioned in pin
assembly 70 between pin member 90 and pin housing 100 to insulate electrically
these from each other, and also pin housing 100 from inner conductor 112
~Figure lb). Dielectric 110 essentially fills aforesaid space. Dielectric
110 extends back beyond pin housing barrel (tail) portion 106 a substantial
distance underneath outer conductor 80, when this is present, so as to under-
lie a ferrule 130.
Herein, dielectric 110 is fitted as three pieces 114, 116 and 118
(Figures la-lb~. Piece 114 goes forward to squared end 120 to insulate pin
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92 from nose end 44 when the pin and socket are mated.
Dielectric piece 118 extends roughly from the outer end 131 of
ferrule 130, at the approximate level of the outer surface of tail portion
106~ underneath ferrule 130, end portion of braid 82~ tail portion la6,
and forward until it abuts the rear end 117 of dielectric piece 116. Piece
118 is provided with a shoulder 119 aga;nst which the inner end of cable
dielectric 132 abuts in forward axial movement and is barred from further
movement toward the inner pin-socket contact zone, thereby minimizing
electrical disturbance caused by cable dielectric axial movement. Shoulder
120 abutted against end 107 of tail portion 106 helps restrain forward
movement o dielectric material 110.
Dielectric 116 runs into dielectric 114, described earlier.
Because of the characteristics of dielectric materials 50 and 110
there is no thermal elongation to force pin 92 and socket 32. Thus inner
pin-socket contact is further captivated against axial movement.
Pin assembly 70 includes a conductive ferrule crimp means 130.
Ferrule 130 encircles: p;n housing barrel (tail) portion 106, pin assembly
dielectric material 1-18, end portion 108 of outer conductor 80, cable inner
dielectric 132, and that portion of cable inner conductor roughly under
ferrule 130. Ferrule 130 is of metal capable of being crimped to fasten
together (1) the ferrule, outer conductor and the encircled tail portion;
and ~2) the ferrule, outer conductorJ and dielectric 118 extending beyond
the tail portion. The crimp (2) restrains the inner pin-socket contact
against rearward pull of inner dielectric and inner conductor.
Pin assembly 70 is prGvided with ~Figure la~ a stainless steel
protective sleeve, cylindrical, 140, positioned on the exterior of pin housing
100 to protect the spring fingers at the forward end 103 of pin housing nose
~ortion 102.
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I~LUSTRATI~N: A suitable coaxial cable for termination by the
contact assembly of the ;nvention is RG 142/U in size 12 contact in conjunct-
ion with a multipin electrical connector. This cable has a solid copper inner
conductor; a PTFE dielectric (polytetrafluoroethylene); a braided copper
outer conductor; and a FEP protective jacket (fluorinated ethylene propylene).
In the contact assembly, the pin and socket members, the p;n and socket
housings, and the cylinder with spring fingers are made from heat treated
beryllium copper alloy. The ferrules are soft berylliumcopper alloy. The
dielectric material is polyamide.
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