Note: Descriptions are shown in the official language in which they were submitted.
wo 92t15128 210 3 ~ 0 3 pcr~Gss2/oo2o8
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SEALED F~ FCl RIC.~L CONNECI OR
The present invention reilates to ~n environment~llv-se~led
electrical connector~ particularly one forming at least part of a ~
telecommunica~ions or other connector block. `
Connec~or blocks may be used in the following way. A
telephone distribution cable~ for example, may contain hundreds of
pairs of conductors. It may run from a central office and perhaps
after branching one or more times will terminate in a small number
of drop wires leading to subscribers. The branches will also end in
drop wires to subscribers. These connections between a number of ~ ;
drop wires and the cablei will occur at a distribution point. Also, ~
cables may need to be joined together in a way that allows their ;
conductor interconnections to be rearranged. That occurs at a cross-
connection point.
'
Rather than have a large number of loose connectors at a
distribution or cross-sectional point, it is normal to provide a
terminal block or cross-connection block which can be used to
connect a number of pairs, such as 3, 5, 10, 25 or 50. Terrninal
blocks will normally have incoming conductors perrnanently attached
and outgoing conductors removeable; and cross-connection blocks ;
will usually have all conductors removeable. The term "connector
block" is used herein generically.
Connector blocks may be used in ground le~el cabinets or
pedestals, on a pole, suspended from a wire or mounted on a wall etc,
or they may be found in or out of doors.
.
Particularly where they are used out of doors. some form of
environmental protection will be desirable. It is especially important
: '.
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to prevent moisture reachinP any electric~l contacts since moisture
will impair the signal carried by the conductors connec~ed bv the
blo~,~;, and will ultimately lead to corrosion ~nd failure,
Prior art terminal blocks in wide use comprise oblong blocks of
insulating material having pairs of so-called binding posts passing
through them. The binding pOStS extending from the base of the
block are connected to the conductors of a distribution cable by, for
example, wire wrapping. The conductors and the wire-wrapped
posts are then potted in a curing composition making permanent
connections. The binding posts also extend above the block and end
in a screw thread. Drop wires to subscribers are wrapped around
these screw-thread posts, and a nut is screwed over them to form ~
releasable conneclion.
The screw-thrcad posts and nuts corrode, and it was proposed
in US 4600261 (Raychem) to protcct thc posts by placing over each
of them a cap fillcd with a gel. The gel is said to have a cone
penctration value (ASTM D217) from 150 - 350 (10-1 mm), an
ultimate elongation (ASTM D638) of at least 200%, a maximum
tensile strength of 20 p.s.i., and a cohesive strength greater than its
adhesive strcngth. The gel is maintained under compressive contact
with the binding posts etc.
~, .
US 4610738 (Raychem) discloses a splice case for electrical
conductors comprising first and second containers hinged together.
One~ containcr is slightly larger than the other so that when the splice
case is folded shut one container partially telescopes within the
other. The containers are filled with a gel.
Mention may also be made of US 4662692 (Raychem) which
discloses a termination block sealing member which includes a
continuous layer of insulating gel enclosed around its perimeter by a
plastics container such that exposed faces of the gel are open. A
~ ~ .
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~ .
plurality of con~act pins c~n be pierced throu~h ~he gel to make
contact with sermin~tions in ~he termirlal bloc~;.
US 4070543 (l`hompson ;lnd Gilliemont) discloses ~ reenter~ble.
waterproof, encapsulated splice ~ssemblv It comprises ~ pair of
cup-shaped telescoping housing members containing ;~ gel~ e
potting compound.
Use of a grease in an electrical wire connector is disclosed in US
4444447 (3M). A hollow open-topped body telescopes with a cover.
A slotted, flat plate, wire connector is retained on the base of a U-
shaped wire cut-off and strain relief element relained centrally
within the body.
The disclosure of each of these patents is incorporated herein
by reference.
I havc now designed an improved connector that allows good
environmental sealing and ease of access to its electrical contacts.
Thus, the present invention provides an electrical connector,
comprising:
(a) a housing comprising a first hollow part and a second
(preferably hollow) part that can be moved relative to the first
part to open and close a space between the first and second
part;
(b) an electrical switch (preferably comprising an insulation-
displacement connector, particularly of split-beam design)
within the housing that is arranged such that a connection is
made automatically on closing said space, optionally when a
conductor is located at the first or second part;
. ,., .. . ,... ; ...... . . , . , . -. ............................ . ~
.. ~., ,. . - . , ... , ... . ,.. - ., ... " - .. ~, . .. . .. ..
~u~v~ ~
wo 92t15128 PCl'tGB92/00208
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c) ~ se~ling m~teri~l. preferably comprising ~ gel. especially
in sheet form. within the space. arld preterabl~ subst~nti~llv
filling the space. tha~ is substantiallv entirelv enclosed when
the space is closed:
(d) optionally a socket accessible from outside the housing,
contacts of which are electrically-connected to said electrical
switch, th~: socket preferably being sealed by a gel or other
sealing material;
(e ) optionally a plug for the socket (d), the plug preferably
providing electrical connection between components of said
switch via an overcurrent protector and for providing electrical
connection between the switch and an electrical ground via an
overvoltage protector; and
(f) optionally means, such as a spring, for maintaining, and
preferably for putting, the sealing material under compression.
The sealing material preferably has the properties mentioned
later. ;~
The means for maintaining the gel or other sealing material
under compression may comprise a spring or other resilient member,
optionally together with a lever, latch or nut and bolt etc. and it may
urge ~the first and second parts together.
Tho first and second parts are preferably pivotally-connected,
for example by a living or other hinge. In a preferred embodiment
the connector comprises first, second and third parts having a cross-
section, if pivotally moved to be partially open, substantially the
configuration of a letter Z. This is to be regarded as a topological
description of the parts~ and it is not necessry that pivoting be
~,
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possible to such an ex~enn Wide opening of one or both pairs of ~he
parts is. however, preferred.
'~
The connection in ~he connector housing is prefera~ly made
automatically between an insulation-displacement connector ~nd
: '
(i) an electrical contact, the connector and/or the contact
being resiliently deformable and on moving the first and
second parts to close the space being forced together causing
one or both to be deformed against its resilience; and
(ii) said conductor through insulation thereof, when said
conductor is located at the ~lrst or second part.
The invention may additionally or alternatively provide one or
more of the following.
An electrical connector having a housing, comprising:
(a) a first part,
(b) a second part pivotable about a first line to open and ?
close a space between the first and second parts, and
(c) a third part pivotable about a second line
of the first part optionally to open and close a space between
the first and third parts.
A telecommunications connector block for connecting together first
and second conduc~ors, which comprises -
(i) a housing comprising
( a ) a hollow first part, and
(b) a second part attached to the first part and
which can be moved relative to the first part to open and
close the housing,
.. - . .,. . ,,. ., . .. ~ , . ., . ". . .. .
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( ii) ~ switch within ~he housing, comprising
( a ) ~ first contact that can be connected to the
first conductor, and
b) a second contact that can be connecled
to the second conductor,
the parts and the contacts being so a~anged that opening of the
housing automatically opens the switch, and closing of the housing
automatically closes the switch.
An electrical connector, which comprises
(a) a first part having an electrical contact and means
for locating an insulated conductor;
(b) a second part having a split-bcam first insulation-
displacement connector,
the first and second parts being movcablc relative to one another to
open and close a space between them, such that
on moving the first and second parts to close thc space the
insulation-displacement connector makes electrical contact with
(i) an insulated conductor located in the means for locating,
contact being made through insulation of the conductor and
(ii) said electrical contact.
A split-beam electrical connector, in which the beams
at the split are bent between proximal and distal ends thereof.
A spllt-beam insulation displacement connector having a
~; , '
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~ i~ 2 1 o 3 ~ o ~3 PCJ/GB92/00208
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configur,~tion such thal insertion ot ~ conductor therein c~uses
torsion of at least one the beam.
.~ resilient elect:ric~l connec~or into which ~ conductor may
be inserted thereby deforming the connector against its resilience~
mode of deformation of the connector varying with extent of
insertion .
An electrical connector having a housing, comprising:
( a ) a first part,
( b ) a second part pivotable about a line adjacent a ~lrst
a third part pivotable about a line adjacent a second
edge of the first part optionally to open and close a space
between the first and third parts; the second edge being
adjacent or substantially. opposite the first edge.
An electrical connector which comprises
(a) a housing comprising
(i) a first part, and
(ii) a second part moveable with respect to the
first part to open and close the housing;
(b) a first electrical contact carried by the first
part; ;:
(c) a second electrical contact or means for locating a
conductor carried by the second part, such that when the
housing is closed electrical contact is capable of being made
between the first contact and either the second contact or the
conductor;
(d) electrical ground;
'
'
) U -3
wo 92/15128 pcr/GBs2/oo2o8
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-8-
e ) means for movin ~he first ;~nd second p~r~s to close
the housing, which means is in electnc;ll contact with the
electrical ground.
.~n electrical connector. which comprises
( a ) a housing comprising a first part and a second
part that can be moved relative to one another~
(b~ an electrical protection device carried by the firs
part and being electrically-connectable to a first
electrical contact that extends within the housing,
(c) a second electrical contact within the housing that
has means for connection thereto of an electrical conductor,
the first and second electrical contacts being arranged such
that connection is made between them on closing the
housing and connection between them is broken on openin~
the housing.
.
An electrical connector, which comprises
(a) a housing that has means for receiving an electrical
protection device.
(b) a first electrical contact having means for connection
to a first electrical conductor,
(c ) a second electrical contact having means for
conncction to a second electrical conductor, and being capable
of being in direct electrical contact with the first contac~ in the
absence of the protection device;
( d ) the protection device, which when received in the
housing interposing an overcurrent protector between the first
and second contacts.
For background information, reference may be made to US
4449777, US 4435034, US 4806119, US 4193201, US 4617602, US
4420792, US 4822306, US 4113340, US 4675779, GB 217602, US
4741711, US 4295703, US Bl 37û8779, US 3793612, US 4759723.
:
WO 92/1S128 210 3 ~ 0 3 PCI/GB92/00208
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IJS 4344664, IJS 3950063. ~nd US ~7641~5. lhe discl~sure of each
of which is incorporated herein by reference.
^ The inven~ion is further illustrated with reference to the accompanying drawings, in which
:
Figures 1 A and 1 B show two perspective views of an electrical
connector of Z-shaped cross-section;
Figure 2 shows lhe connector of figure l in unfolded form;
Figure 3 shows several connectors positioned together to form ?
a terminal block;
Figures 4 and 5 show ways in which connectors can be used to
-` join conductors;
Figures 6A, 6B and 6C show the installation of a protection
module into a connector;
Figure 7 shows a casing on which connectors may be mounted;
Figures 8, 9, 10 and li show other designs of connector;
Figure 12 shows a connector whose parts slide with respect to
onc another, and
i Figures 1 3A and 1 3B show an insulation-displacement
connector.
.;
.,~ .
Figures lA and lB show an electrical connector 1, of substantially Z-
shaped configura~ion in cross-section, and used to connect together
electrical conductors such as telephone wires. Figure lA is a view
from above and figure lB is a view from below. Since telephone
lines employ pairs of conductors, the connector will in ~eneral have
' one or more pairs of contacts etc. In the following discussion,
however, connection of single wires will be referred to for simplicity.
The connector has a first part 2 and a second part 3 pivotable
about its rear edge as drawn, thus allowing opening and closing of a
space between them. A third part 4 is pivotable about a front edge
.
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WO 92/15128 210 3 .i 0 3 PCr/GB92/00208
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ot the first part '~ similarly to allow openin~ ~nd closing of ~ space
between then. In generah the first ~nd/or second and/or third p~rts
will be at least partiallv hollow. The spaces may contain first and
second insulation-displacement or other connectors 5 and 7~ carried
preferably by the second and first parts 3 and ~. Such connectors
obviate the need for conductors to be pre-stripped at their ends.One
or more of the parts (preferably the first and third parts) has means
for locating a conductor which may, for example, comprise a hole or
recess 6A in an outer surface and/or a protrusion or other guide 6B
within the space between the parts. The parts may pivot about
hinges or other means 8 and 9. Living hinges. preferably integral
with the parts 2, 3 and 4, are preferred.
The first insulation-displacement connector (IDC) is eiectrically
connected to, and preferable is integral with, a first electrical contact
10. The first part 2 carries a second electrical contact, which is
clcctrically conncctcd to, and preferable integral with, thc second
IDC, 7.
When the first and second parts 2, 3 are closed by pivoting
along line 8, the first and second electrical contacts 10, 11 are
brought togethcr. They therefore constitute a switch within the
connector housing. The result is that the two IDCs 5,7 become
electrically connected, thereby joining any conductors carried by
them. In this way the connection (say between central office and
subscriber) may be made and broken, and if need be the connector
may be open and closed without IDC connections being disturbed. ~ -,
. ~
This electrical connection between the contacts 1 0, 11 may be
direct, or it may require some funher component such as an
overcurrent protector between them. In this sense, the connection
may be said to be "capable of being made" when the parts 2 and 3
~` are brought together.
~:
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wo 92~15128 21~ 3 ~ 0 3 pcr/GBs2too2o8
The ~ction of bringing ~ogether Ihe first ~nd second parts ~. 3
or the first and third p~rts ~ 1) may ~lso dnve ~ conductor into the
IDC 5 (or 7). This may require a significant force and means may be
provided for moving the parts tO close the housing of the connector.
Such means may comprise a bolt that passes through the second (or
third) part into a nu~ 12 in the first part 2. The terms "nut" and
"bolt" are used herein in a broad sense to include any female/male
connector where some turning motion is involved, and includes
screws, cams and bayonet fixings. An alternative is an over-centre
latch or other lever-action device. `
The housing of the connector may have a cover 13 for enclosing
an access point tO the first and second contacts 10, 11, or other
component within the housing. Such an access point may allow for
testing of thc contacts (for example to de~ermine line voltage or
continuity in both or either direction) or for addition of other
electrical components. Othcr electrical components may comprise
electrical protection such as the overcurrcnt protector mentioned
above (in series between the contacts) and/or an overvoltagc
protector between onc or both contacts and ground. A further use oS
the access point may be for tapping-off to further telephones, or
other telecommunications equipment. Due to the various uses of the `~
access point, it may be referred to as a "fle1~ibility point", providing ;
the connector with increased versatility.
. .
The access point is preferably environmentally-sealed to ~ -
protect ~he contacts 10, 11 or other parts of the connector. Such `
sealing may be provided by a cover 13 and/or by a sealing material
such as a gel, particularly one having the following properties: a cone ~`
penetration from 100 - 400, especia!ly 150 - 350, particularly 250 - -
350 (l~~ lm~n), an ultimate elongation of at least 100%, particularly ~`
at least 300%, especially at least 500%, a maximum tensile strength~`
of substantially 20 p.s.i, an elastic modulus of less than 107,
especially 106, particularly 105 dynes/cm2, and a cohesive strength
!~':'.'i:: : ' .: . , ' . . ' ': 'i , , : ` .. . . . .
WO 92/15128 21 0 3 8 0 ~ PCI`/GB92/00208
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gre~ter than i~s adhesive strenPth to componenlS of the connector.
Cone penetration is determined in accordance with ASTl~l D~ 17-68.
cone weight lû2.5g, shaft weight 47.5g), ~nd elongation in
~cc~rdance with ASTM D638-80.
The. sealing material may be prepared by extending ~
polymeric material with a vegetable and/or mineral oil. The
resulting materia~ may be thermoplastic. or it may be formed by
cross-linking the polymeric material. The polymeric material may
comprise a block copolymer, for example one having c~ystalline end
blocks and elastomeric centre blocks. An exarnple is a styrene-
ethylene butylene-styrene block copolymer, for exarnple that known
by the trade mark Kraton G1651. Such a material may be used with
from 700 - 1200, particularly 900 - 1100 parts by weight of
plasticizing oil to 100 parts of a block copolymer. Other gels can be
; made based on oil-extended polyurethanes or silicones.
The spaccs between the parts are preferably at least partially
filled with such a sealing material, preferably in sheet form. Means,
3 such as a spring, is preferably provided for maintaining and
optionally for putting the sealing material under compression.
A device, such as an electrical-protection device, that is applied
at the access point is referred to herein in preferred embodiments as
a "plug" and a part of the housing that receives it as a "socket".
These terrns are used in a broad sense with reference to the
functions of the plug and socket and their relative sizes: whilst we
prefer that the plug has male electrical contacts, and the socket
female, the situation could be reversed. Also, the second (or other)
part of the housing may have a recess within which the plug is at
least partially received, but this is not necessary.
Where the plug is tO provide overvoltage protection it will, in
general, need to be electrically connected to ground. In this way, it
WO 92/lSt28 2 i 0 3 ~ 0 3 PCl/GB92/00208
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can shun~ anv overvoltaPe c~used for example by lightning or m~ins
vol~age cross away from equipmem connecled by the connector~ ~nd
down to ground. The protection device will remain insulating ~I the
normal opera~ing voltages of the conductors~ but will become
conducling at the higher fault voltage. A ground connection may be , ;~
provided within ~he connector housing and that may be in turn
connected to some casing to which the connector is attached. A bolt
that closes the part of the housing, and that mates with nut 12 may
be in electrical contact with electrical ground. The protection plug ~ s
may make contact with the head or other part of the bolt. A
connector housing of slightly different design from that illustrated
may then be preferred, so that the bolt and contacts 10, 11 are closer
together aDd such that a plug and cover 13 cover both.
The IDCs 5,7 are shown as split beam connectors, and they are
more fully illustrated in Figure 13. Their beams are bent at their
split between proximal and distal ends. As a result when a `
conductor is inserted into a slit, thc connector, which is preferably
resilient, is deforrned against its resilience, thc mode of deformation
varying with extent of insenion. Also, energy is stored over a large
extent of beam. As a result an IDC of small absolute size, and
especially of small size perpendicular to thc plane of the conductors. ~
is able to accept conduc~ors over a large range of sizes. ~.
The connector may be provided with strain relief for the
conductors, and/or means for cutting the conductors to length
especially on closing of the parts.
Figure 2 shows the connector 1 of figure 1 unfolded such that it
lies substantially flat. Preferably the three parts 2, 3, 4 are integral
with one another, the part being manufactured by moulding, for
example injection moulding. Preferred materials include
polypropylene (useful for living hinges) and or various engineering
plastics .
.~.. ... . . .. . . . .. ... . ........... ..
.: . ,. ..... .. - ~ . .: . , , ; - . - , , . . . .. -
.. . . .. , . - . . .... . - - .. . .
.... .. ..
wo 92~15128 21 o 3 ~ 0 3 pcr/G~92/oo2o8
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!
The third part ~ ~or other p~rt~ mav be provided with
complemen~ary joining means such as dove-tail protrusion 14 and
recess I S whereby a connector can be joined side-bv-side to a
similar connector.
~'
Figure 3 shows several such connectors joined side-by-side.
Bolts 16 are shown having been used to bring or maintain together
various parts of the connectors, and optionally tO provide ground
connections.
~,
Figures 4 and 5 show two ways in which the connectors 1 can
be used to join conductors 17 and 18. The third part 4 acts as a base
(hence the use of that part in figure 2 for interconnecion of adjacent
connectors) which may be secured to some casing etc. An insulated ~,~-
conductor from, for example, a telephone central office, is placed in
some mcans for location 6 of the third part 4. This is shown in figure
4A. Thc thîrd part 4 and filrst part 2 are ~hen closed as indicated by
the arrow, causing an IDC on the underside of the first part to cut
through insulation of the conductor 17 and make electrical contact.
Then a further insulated conductor 18 leading to, for example~
a subscriber, is placed in means for location 6 on the upper surface of
the first part 2. See Figure 3. The second part 3 is then closed as
shown by the arrow, causing an IDC in the first part tO make
connection to conductor 1~. When the second part is closed, the two
IDCs make contact with each other, to connect together the
conductors 17 and 18, as shown in figure 4C.
Figure S is similar except that in figure SB means for location is
provided at the lower surface of the second part 3, and an IDC is
provided on the upper surface of the first part 2. -
. ., ^ ~, ., , ,~ .. . . - - . , . .~ ....... .. -.. - - .. . . . .
- . . - ; . , -
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WO 92/15128 21~ 3 ~ 0 3 PCr/GB92tO0208
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Figures 6A. 6B ~nd 6C show ~hree steps in the provision of an
electrical protection device. or other plug. in a connector.
Figure 6A shows a connector I having a cover 13 that is shown
closed. In figure 6B it is open and ~ piug 19 is about to be mated
with socket 20. Figure 6C shows the plug, now inserted, covered by
the cover which has been folded over it. The cover has a first
surface 21 that is now venical (as drawn) and a part 22 that is now
horizontal and covers the top of the plug. In this way a cover 13 is
provided that can seal socket 20 when empty, and also can seal plug
19. rhus, the connector can be used with full environmental sealing
with or without the plug.
A casing 23 is illustrated in figure 7, within or on which are
mounted a plurality of connectors 1. Two are shown but more, such
as 10, 25 and 50 may be provided. The casing plus connectors may
be posidoned in or adjacent a cable splice case, or o~her housing such .
as a cross~onncct cabinet or a pedestal, and i~ may be positioned at ~ ~ ~
ground le~el, on a pole, suspended from a wire or attached to a wall `
etc. The casing 23 may provide a sealed housing or it may compnse `
merely a frame or other support.
The casing 23 illustrated has rails or guides 24 over which
connectors I are positioned. The rails 24 may be electrically
conductive and connected to ground, thus providing means for
grounding some component within the connectors. The bolts 16 may
mate with the rails 24. The casing may-have a cover 25 and locating
means 26 for the incoming or outgoing conductors. Sealing material
27 may seal the cover to the base.
Figures 8, 9, 10 and 11 show other designs of connectors, each
having first, second and third parts 2, 3, and 4 that hinge together.
The designs illustrated are for three pairs of conductors. Two IDCs 5
are provided for each pair (shown) above and (hidden) below the
,, , . ;. ., i - . . ~ .
: . . : . . -. . ~" .
, . - , - . . , -
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WO 92/15128 210 3 8 0 3 PCr/GB92/00208
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first part ~. A protection plug extends ~hrough socket 0 to connec
together ~he contacts 28, optionally via an overcurrem pro~ector
and/or to connect either one of them to ground via an overvoltage
protector. One of the contacts 28 is integral with the visible IDC 5,
~nd the other extends through the plane of the first part and is
integral with the hidden IDC.
Figure 9 shows a drop cable 29 containing three pairs of
conductors 30, located in the third part, 4. When the third pan 4 is
folded over the first part 2, the conductors are driven into the IDCs S. i
A single third part 4 provides for several (here three) pairs of
connections.
An opposite side of such a connector is seen in figure 10.
Individual second parts 3 are provided for each pair of connections.
A ground plate 31 is shown below the base of the connector. A bolt
for driving thc parts together may be provided, and it may mate
with thc plate 31.
In figurc 11 slabs or other sheets of a scaling material 33 are
provided between the parts 2, 3 and 4 of the connector. The sheets
33 may be positioned between respective pairs of parts after the
conductors have been positioned. Alternatively, the connector may
be supplied with a sheet 33 preinstalled at one or more of the
appropriate surfaces of the parts. The sealing material preferably
substantially fills any space between the parts. Also, it preferably
contacts all otherwise exposed connectors or other metal-work
within the connector. In this way an excellent environmental seal
can be achieved. In less damaging environments, a mere seam seal
of sealing material may be sufficient, provided around or adjacen~
peripheries of the parts 2, 3 and 4. Each pair of parts is preferably
re-openable, and if a suitable sealing material is used removal and
reconnection of central office as well as subscriber conductors is
possible.
.~.. ,.. .. .,.. ,.. , . .. , , . - . ~.. .. . .... . .
WO 92/15128 21 o 3 ~ ~ 3 P~GB92/~208
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The sealing material preferablv comprises a gel such ~s that
mentioned above. .~/leans. such as a sprin~, is preferably provided
for maintaining, and optionallv for putting, it under compression. An
expansion cavity may be provided into which sealing material may
pass on closing the parts and/or on insertion of a conductor.
Figure l 2 shows a connector l having ~lrst, second and third
parts 2, 3 and 4 that slide together, preferably telescopically, rather
than pivotally. A connector may be provided that combines at least
some of the features of a pivoting design and at least some of ~he
features of a sliding design.
.. . . .
A conductor 17 from a telephone central office etc passes
through a locating means 6 such as a hole in a wall of the first part 2.
When part 4 is slid in the direction of the arrow into, over or
, otherwise with respec~ to part 2 the conductor 17 is driven into IDC
7.
;;
A subscribcr drop wire 18 is located in means 6 of the first
part 2 and is likewise driven into IDC 5 by sliding the part 3 into,
over or otherwise with respect to part 2. Contacts 10 and 11, which
are connectcd to (and preferably integral with) IDCs 5 and 7, are
themselves connected together by plug 19 on insertion thereof into
socket 20. As mentioned in connection with the designs above, plug
19 may connect contacts lO, l 1 via an overcurrcnt protector and/or
may connect either of them to ground via an overvoltage protector.
A bent IDC S is shown in figure 13A. The IDC is of the split-
beam type ha~ing beams 34 and slot 35 between them. The IDC
preferably comprises a phosphor-bronze or beryllium-copper alloy.
In particular, IDCs (especially those for incoming wires from a central
office) comprise a 0.5 to 0.75 hard phosphor-bronze C51000 or
C5l900 which are nominally Cu-SnS and Cu-Sn6. Such materials
have good elasticity without excessive stress-relaxation. IDCs for
. . .
:,'
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WO 92/lS128 2 ~ a 3 ~, O i~ PCr/CB92/00208
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drop wires to subscribers, which may be re-en~ered more often, may
have more stringent requirements of elasticity, ductility (allowing
sharp bends) and hardness. The material preferably has a yield
s~ess of at least 300, especially 350 MPa. and is preferably hard
enough to deform bronze and steel wires. If its conductivity is not
sufficient, it may be plated. The drop IDC preferably comprises Cu- -
Sn8 C52100 hard, Cu-SnlO 52400 hard, Cu-Sn5 C5100 hard or Cu-
Sn6 C51900 hard. In general, we prefer a modulus of 90000 - ¦
1 40000, especially abou~ 11 0000 MPa, and a tensile strength of
greater than 400 especially 450 MPa. The ductility preferably allows
the material to be bent at a radius of the material thickncss, or
greater than 5%. Hardness is preferably at leass 70, especially 72
Rockwell B. An example of a beryllium-copper alloy is C17200,
which may require hardening by heat treatment. A spinoidal alloy
such as Cu-Ni-Sn C72700 may be suitable. The beams 34 at the split
35 are bent between a distal end and a proximal end thereof. Thus,
the slit extends as it were around the bend. Preferably the beams
have a substantially planar first part 36 distal of the bend and a
substantialiy planar second part 37 pro~cimal of the bend. The slit
may terrninate at a cut away portion 38 to avoid stress
concentration. Thc IDC is shown mounted on a support 39. On
insertion of conductor 17 into the slit 35 as shown by arrow A the
initial deformation of the beams will be predominantiy as shown by
arrows B. This involves torsion of the proximal parts 37 as shown.
As the conductor advances in the slot 35 between the distal parts 36
the mode of deformation will vary to become predominantly bending
of the proximal parts 37 as shown by the arrows C.
The length D of the second part is preferably 10-20,
particularly 12-i6, especially about 14 mm, and that (E) of the whole
horizontal part is preferably 25-30 mm. The width F of the IDC is
preferably 5-10, especially about 8 mm, the slit being preferably 2.5
- 4.5 mm at the second part and sharpened edges of the beams
preferably substantially touching one another at the distal part 36.
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WO92/15128 2.t~3 ~? O ~ PCI/GB92/00208 1 ~
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19~
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The length G of the distal p~rt is preferably 6 - 14, especially 8 - 12,
particularly about 10 mm. Preferably, the length D is from 1.2 - 1.6,
pa~ticularly about 1.4 times the length G. The material thickness of
the IDC wil1 typically be from 0.8 - 1.2, especially about 1 mm.
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Figure 13B is an end view of an IDC of the type shown in figure
1 3A. Here, however, the IDC is provided with stop means 40 which
may be part of a support 39 or a connector housing. Stop means 40
sen~es to lin~it free deforrnation of thc IDC. Thus, for larger
conductors some deformation of stop means 40 will additionally be
required, thus increasing the force exerted by the IDC on the larger
conductors.
For the avoidance of doubt it is noted that the invention -
provides an improved connector, IDC, connection block and mothod
of connection. Any of thc conncctors, IDCs, contacts, housing or
casing designs or protector designs may bc sclccted.
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