Note: Descriptions are shown in the official language in which they were submitted.
WO 91/16738 PCT/GB91/00584
This invention relates to a device for disconnectably connecting cable wires
to a contact plate.
and particularly to such a device designed to engage two different cable wires
in a housing of
electrically non-conductive material, preferably plastics material, wherein
one of the cable
wires to be contacted can be brought into contact with the contact plate,
preferably, by means
of a screw element.
An electrical contacting device for connecting cable wires is known, for
example, from EP-0
315 345-A2. In the known device. contact plates are provided in pairs in a
plastics housing.
The contact plates have metal slots on both sides which, are in the form of
cutting blades, and
are thus able to cut through the insulating jacket of the cable wire to be
contacted and clamp
the metallic conductor inside them. An electrical connection is thus made by
means of this
contact plate between the two contacted cable wires. If one of the cable wires
has been pre-
installed, for example at the factory, the idea of such devices is to insert
the cable wire to be
connected and press it by means of a thrust element between the cutting blades
in the
contact plate. In the known solution, this is achieved by means of a cap screw
with the aid of
which cable wires are pressed in pairs into contact plates arranged in pairs.
The known solution has a number of advantages, but does involve some
disadvantages. As
examples the following may be mentioned.
(1 ) The contacting mechanism is relatively complicated in that, in order to
press the cable
wire between the cutting blades, the cover of the device has, in practice, to
be moved.
(2) Testing of whether the cable wires have been contacted or not can be
carried out
only with difficulty.
(3) A particular drawback is that, once a cable wire has been pressed in
between the
cutting blades of the contact plate, it is very difficult, if not impossible,
to release and withdraw
the cable wire so contacted, for example if it has not been installed
correctly. In order to do
this. it is necessary to unscrew the entire lid so that the contacted cable
wire can be lifted out
using a tool.
An object of the present invention is to provide a solution which simplifies
construction, and
which renders possible both testing for contacting and easy removal of a cable
wire once
contacted should the cable wire have to be replaced.
SUBSTITUTE SHEET
WO 91/16738 PCI'/GB91/00584
c
Thus the present invention provides a device for disconnectably connecting
cable wires to a
contact plate designed to engage two different cable wires, wherein the cable
mre to be
contacted can be brought into contact with the contact plate preferably by
means of a screw
element characterised in that
(a) the contact plate is provided with a through opening for the cable wire to
be
contacted, and
(b) a thrust piece is provided, which surrounds or overlaps at least part of
the contact
plate and is longitudinally displaceable thereover, wherein the thrust piece
is also
provided with a through opening, corresponding to. and movable relative to,
the
tnrough opening in the contact plate.
Preferably the device is mounted in a housing of electrically non conductive
material.
Preferably the contact plate is secured non displaceably in the housing.
The invention provides a number of advantages compared to the known solution
described
above. For example it is possible to use simple components, for example
rotationally
symmetrical components. The through openings in the thrust piece can be used
not only for
contacting, but also for releasing a cable wire once contacted. This is
described in detail
hereinafter. The force to be applied in contacting can be controlled in a
simple manner. and
so on.
Further advantages of the invention are apparent in preferred embodiments of
the invention
which are described hereinafter.
For example testing means may be provided to check the electrical contact
made. In one
embodiment a test vane is provided integrally, but at an angle to the contact
plate.
Alternatively one region of the contact plate itself can be used for testing.
in which case test
bores may be made in parts. for example m screw elements. that are provided
electrically
connected to the contact plate.
In order to fix the contact plate spatially in a simple manner, the contact
plate is preferably
provided with locking elements to secure the contact plate in the particular
receiving housing
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WO 91/16738 PCT/GB91/00584
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-3-
The locking elements are preferably splayed outward in the same plane or
folded over at right
angles during installation
By providing the thrust piece with a through opening, it is equipped not only
with a thrust
surface (to urge the cable wire into contact with the contact placel. but by
reversing the
movement (preferably screwing movement) which effected the contact, it is
possible to lift a
wire that has been pressed into contact, out of contact. thereby releasing the
wire.
In a first preferred embodiment the contact plate comprises a sheet metal vane
having
toothed outer edges. These toothed edges preferably project through
longitudinal slits in a
guide cylinder which is provided on, or extends from the thrust piece.
Preferably a threaded
insert element, eg a threaded cap is provided which has an internal thread
arranged to slide
over the guide cylinder and to engage the toothed outer edges of the contact
vane. Thus
the guide cylinder, together with the thrust piece, can act as a plunger which
can be moved
downward and upward relative to the contact plate, for example by turning the
threaded
element.
In a second preferred embodiment the thrust piece is moved relative to the
contact plate by
the action of a drive cylinder which abuts against the thrust piece. The drive
cylinder is moved
axially relative to a housing for the device. Preferably this is achieved by
providing an external
screw thread on the drive cylinder, and a corresponding internally threaded
ring, which
surrounds the drive cylinder, and is fixed relative to the housing. The drive
cylinder is
preferably separate from, but may be integral with, the thrust piece.
The through opening in the thrust piece is preferably substantially similar in
shape and size to
the through opening in the contact plate. In use, before insertion of a cable
wire, the through
opening provided in the thrust piece is positioned in register with the
through opening in the
contact plate. Then a cable wire is inserted into the in-register through
openings. Finally the
through opening in the thrust piece is moved (preferably downwards) relative
to the through
opening in the contact plate. In the first preferred embodiment described
above this can be
done by screwing the threaded insert onto the toothed edges of the contact
plate. This
relative motion of the through openings in the thrust piece and the contact
plate causes
edges (preferably the upper edges) of the through opening in the thrust piece
to force the
cable wire against edges (preferably the lower edges) of the through opening
in the contact
plate. thereby cutting through any insulation on the cable wire to contact the
conductor
within. In the second preferred embodiment described above, the relative
movement of the
through openings in the contact plate and the thrust piece can be achieved by
screwing the
SU~;aTfTi UTE Sh~EE'1~
WO 91/16738 PC1'/GB91/00584
2~'~~6'~4
drive cylinder into the surrounding fixed ring, causing the drive cylinder to
push downwards
on the thrust piece.
If it is desired, later, to withdraw the inserted cable wire, the through
openings in the contact
plate and the thrust piece are simply moved back into register, for example in
the first and
second preferred embodiments, by unscrewing the relative threaded elements,
causing the
lower through opening in the thrust piece to lift the cable wire upwards from
its engagement
with the contact plate, thus allowing easy withdrawal. This arrangement
minimises the
possibility of the insulation of the cable wire being trapped by the edges of
the contact plate if
the cable wire is withdrawn. Thus the through opening in the thrust piece can
act both to
force the wire into contact with the contact plate, and to release the wire
from the contact plate
for withdrawal.
tt should be noted that all references to upwards, downwards, upper, lower,
vertical and the
like are used for convenience. They indicate only the relative positions of
the component
parts of the device.
The through opening in the thrust piece may be provided in a number of
configurations. In
one embodiment it is provided as a bore through a solid end of the thrust
piece. In this case, it
acts on the wire on both sides of the contact plate. fn a preferred
embodiment, the through
opening in the thrust piece is provided as an aperture in a substantially
planar projection at
one end of the thrust piece. In this case the aperture in the projection is
preferably arranged.
in use, to be only behind the corresponding through opening in the contact
plate (the word
behind being used in relation to the direcUOn of insertion of the cable wire).
This arrangemen;
has a number of advantages. For example, it minimises the possibility of the
core insulation
being trapped within the device if a cable wire is withdrawn. Also it allows
easy entry of
insulating sealing material. such as gel, around the contacted wire. as
described hereinafter.
The thrust piece is preferably also equipped with longitudinal guides so it
can slide within a
housing in the axial direction but cannot rotate.
Where the through opening is in a plate extending from one end of the plunger
on one side
only (preferably behind) the contact plate. the longitudinal guides on the
thrust piece are
preferably arranged such that the thrust piece can only be inserted into the
device housing in
one orientation, viz so that the through opening at the end of the plunger is
correctly
positioned.
SUBS'~I'T'U~'E SHEET
WO 91 / 16738 PCT/GB91 /00584
2~f'~96"~4
The guides on the thrust piece may be channels or ridges, on its outer
surface. which mate
with corresponding ridges or channels on the inside of the bore of the
housing.
In the first preferred embodiment described above, comprising a guide cylinder
and a
threaded insert. the thrust piece is preferably provided with an outwardly
pointing annular
projection at its upper edge towards the guide cylinder, and the threaded
insert (fitted over
the guide cylinder) is preferably provided with an outwardly pointing annular
projection at its
lower edge towards the thrust piece. A split clamping ring is then preferably
positioned over
the annular projections. The plunger and the threaded insert are thus
connected to each
other so as to be rotatable relative to each other but to be fixed relative to
each other in the
axial direction. This arrangement faalitates mounting and simplifies
manufacture. The thrust
piece can be guided to slide in the housing.
In one embodiment the split clamping rang comprises a C-shape ring, which is
sufficiently
resilient to allow the arms of the C to be opened and the ring sprung into
position around the
outwardly pointing annular projections on the upper edge of the thrust piece,
and the lower
edge of the threaded insert. In another embodiment the split clamping ring
comprises two
separate or hinged half shells which can be opened to position the ring around
the annular
projections, and then closed and held in a closed position by a mechanical
retaining means,
such as a clip or the like. The latter embodiment is preferred because it
avoids the risk of the
clamping ring springing open during axial motion of the threaded insert and
the plunger.
The device may also comprise a cap having a blind bore which, for example. in
the first
preferred embodiment, described above, can be fitted over the threaded insert
so that
rotation between the cap and the insert is prevented. The cap preferably
comprises an
electrically non-corxluctive material. Preferably the cap is provided with a
screw head so that a
screw driver can be used to turn the cap and hence the threaded insert. A
screw head with a
blind bore. can also be provided in other embodiments.
A resilient element, such as a sprang, is preferably also provided between (i)
whatever element
is moved to act on the thrust piece, and (ii) the thrust piece. For example,
in the first preferred
embodiment, where advantageously a cap is included, the resilient element is
preferably
arranged so that it is compressed between (i) the cap (andlor the threaded
insert) and (ii) the
guide cylinder, when the threaded insert is turned to move the through
openings in the
contact plate and the thrust piece relative to each other. In one embodiment
the resilient
element is compressed between the blind end of the cap and the free end (upper
end) of the
guide cylinder. In another embodiment the guide cylinder has an end portion of
smaller cross-
SUBSTITUTE SHEET
WO 91/16738 PCT/GB91/00584
-o-
section than the remainder of the guide cylinder, so that it presents a
shoulder. In this case
the resilient element is preferably in the form of a helical spring which fits
around the end
portion of smaller cross-section of the guide cylinder. The resilient element,
in this case is
thus compressed between (i) the cap and (ii) the shoulder on the guide
cylinder.
In the second preferred embodiment, described above, the resilient member is
preferably
provided between the drive cylinder and part of the thrust piece.
One purpose of the resilient member in the cap is to exert a continual force
on the guide
cylinder and hence onto the thrust piece, and, in use, an inserted cable wire.
This j~g~
compensates for changes of pressure in the contact region which may occur
after prolonged
use, e.g. due to relaxation of the insulation on the cable wire.
The contact plate is preferably made from metal, especially preferably from
copper. Preferably
the contact plate is punched from sheet metal.
The contact plate contains a through opening, in the form of an aperture in
the contact plate,
for receipt of a cable wire. In use the cable wire is forced against an edge
of the aperture in the
contact plate, causing cable wire to be pinched, and the insulation of the
cable wire cut, so
that the conductor of the cable wire is in electrical contact with the contact
plate. In order to
make this easier, the aperture in the contact plate is preferably prism
shaped, that is it has
straight edges meeting at corners. Preferably the aperture is shaped so that
the wire is forced
between two straight sides. and then along edges tapering from those straight
sides towards
each other. Depending on the size of the cable mre. the mre will need to be
forced a
different distance along those tapered edges of the aperture in order to
pierce the insulation
and contact the wire.
Over pressure of the wire into the aperture (which would cut the wire as well
as the insulatioy
may be prevented (i) onto large wires, by tightening to a predetermined
tension, and (ii) onto
small wires by a physical stop. This physical stop may be, for example,
contact of the inside
end of the thrust piece against shoulders on the contact blade.
For small wires, particularly those with conductors of 0.5mm diameter or
smaller, it is desirable.
to ensure a good contact, to provide a slot at the base of the aperture in the
contact plate.
This slot provides sharp edges which will cut into the insulation of the small
wire.
SUBSTITUTE SHEET
WO 91/16738 PCT/GB91/00584
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_, _
In a preferred embodiment, in order to achieve additional fixing and loading
of the inserted
cable wires. and particularly applicable where the same device is to be used
for contacting
small wires (conductor diameter 0.5mm or less) as well as large wires, it is
preferred that the
device includes a further resilient element which exerts a resilient force
onto the cable wire
which is additional to the force exerted by the thrust piece and the earlier
mentioned resilient
member in the cap eg. in the first preferred embodiment, the resilient element
in the cap.
Thus, eg. in the first preferred embodiment, even where the threaded insert
has been turned
onto the contact plate to its limit, eg until it meets a physical stop, such
as the shoulders on
the contact plate, the further resilient member continues to exert a force
onto the cable wire.
This further resilient member acts independently of the above earlier
mentioned resilient
member eg. the resilient member provided in the cap of the device.
In one preferred embodiment the further resilient member is an elongate shape,
eg in the
form of a strip, bar or rod. The elongate shape resilient member may comprise
a single length.
or may be folded-back onto itself, eg in the manner of a hair grip, to form an
elongate "V" or
"U" shaped further resilient member with a slot through the "arms" of the "V"
or "U". The
further resilient member is preferably arranged at the base of the thrust
member. Where a "V"
or ""U" shaped further resilient member is used it is preferably arranged at
the base of the
thrust piece so that the contact plate can slide between the "arms of the "V"
or "U".
In another embodiment the further resilient member such as a helical spring is
positioned at
the base of the threaded insert. In this case a plate is preferably arranged
within the cap which
abuts the top of the contact plate and hence provided a stop when the threaded
insert has
been turned a predetermined distance. which is determined such that in that
position the
further spring is fully compressed. Thus in both embodiments, for small
cables, an additional
force is exerted onto the cable wire, independently of any first resilient
member within the
cap. This additional force is preferably large enough to ensure good contact
between the
conductor of the cable wire and the contact plate, even it the insulation on
the conductor
relaxes. but not so large that it cuts through the conductor.
In the second preferred embodiment. where an internally threaded ring is used
which
cooperates with an externally threaded drive cylinder to act on the thrust
piece, the internally
threaded ring is preferably fixed in the housing. To do this it is preferably
provided with
locking hooks. These can preferably be fixed in the housing by turning through
90'.
SUB~TfTUTE SHEET
WO 91/16738 PCT/GB91/00584
's-
One or more of the guide cylinder, the thrust piece, and the cap, if present,
preferably
comprise a reinforced polymeric material, eg. a polycarbonate material,
especially a glass fibre
or glass-ball filled polymeric material.
fn a preferred embodiments of the invention the device is equipped with a
means for testing
that a contact has been made between the contact plate and an inserted cable
wire.
In one embodiment including a testing means, the testing means comprises a
test contact
vane which is electrically connected to, preferably integrally formed with the
contact plate.
This additional contact vane is preferably arranged in use so that it is
folded substantially at a
right angle to the plane of the main vane of the contact plate. With this
construction the
device housing is preferably provided with a corresponding test bore into
which the additional
test contact vane extends such that testing of whether an electrical contact
exists between
the contact plate and the inserted cable mre can be carried out by inserting a
testing probe
into the testing bore.
In another embodiment including a testing means, where the device also
comprises a cap of
substantially non electrically conductive material positioned over the
threaded metal insert (as
hereinbefore described), a testing bore is provided into the cap. The bore in
the cap is
arranged to allow a test probe to be inserted into electrical contact with the
threaded insert in
the cap, and hence into electrical contact with the contact plate (since the
threaded insert is
screwed onto the toothed edges of the contact plate). This embodiment avoids
the need for
a separate contact vane on the metal contact plate, and also avoids the need
for a separate
test bore in the device housing.
Another arrangement, which can be used in the second preferred embodiment is
for a
conductive member, eg in the form of a rod, to extend up into the drive
cylinder. Testing can
then be achieved by inserting a test probe into the drive cylinder. eg through
an upper screw
thread.
Preferably two or more, more preferably a plurality of contact blades and
associated plungers
are provided in a common housing.
Preferably, a reservoir for insulating sealing material such as a gel is
provided in the housing.
especially around the entry regions for the cable or cables. Preferably an
overflow space ~s
provided in the housing, to allow for displacement of the gel when a cable
wire is inserted.
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WO 91 / 16738 PCT/GB91 /00584
2'0'~~9rfi ~l ~
The functional behaviour of a gel material, in particular its high elongation,
means that if the
cable wire is withdrawn the gel is dragged back from the overtlow space to its
sealing position
for sealing a newly inserted cable.
Examples of suitable insulating gels are described in US patents 4600261,
4634207,
4595635.
Where a gel is used the contact plate is preferably provided with one or more
further apertures
to allow easy passage of gel through the contact plate. This ensures that the
gel conforms to
the surtace of the cable wire forming a good seal, and is not hindered in its
conformation by
the presence of the contact plate.
fn a preferred embodiment the case is provided with a flexible lip at the
point of entry of the
cable wire. This lip serves jp>~ ~ to prevent or minimise loss of gel from the
housing if a
cable wire is withdrawn. As the wire is withdrawn the fip is drawn towards the
wire. scraping any
residual gel from the surface of the wire insulation as the cable wire is
withdrawn.
The housing is preferably also provided with a stop member arranged to limit
the distance of
insertion of a cable wire.
The invention also provides for the contact elements to be assembled into
blocks in a modular
design, the individual black modules being so arranged on a mounting plate
that the contact
opening for the cable wires to be contacted is arranged on one side of the
mounting plate
whilst the contact plate for the other cable wire contacts. is arranged on the
other side of the
mounting plate. The contact plate for the other cable wire contacts may be
preconnected at
the factory, or installed in the field. Where the other cable wire contacts
are installed in a
factory they may typically be sealed with, for example, a standard potting
composition. Where
they are installed in the field, they are preferably sealed with a gel of the
type described
hereinbefore.
It may be advantageous to cover the reverse side of the mounting plate with a
closure
housing which is provided with insulating gel at least in the region of the
contact modules. As
a development, provision can be made for the mounting plate and the closure
housing to be
pivotally connected to each other.
The same may be said finally for a closure flap covering the contact plane.
which closure flap is
pivotally fastened in turn to the mounting plate andior to the closure
housing.
o~V~r~~e~~r~~ ~~J' ~~~T
WO 91/16738 PCT/GB91/00584
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The latter construction makes it possible for the individual planes to be
opened at any time by
competent persons for work to be carried out. whether it be the plane beneath
the mounting
plate, for example for the post office or a corresponding authohty, or the
side above the
mounting plate for the end user making a connection.
The invention is described in detail below, by way of example, with reference
to the drawings
in which:
Fig. t is an exploded view of a connection element according to a first
embodiment of
the invention without housing,
Fig 2 is a section through a housing region with two connection elements.
Fig 3 is a section through part of the housing, perpendicular to the sectional
view
shown in Fig. 2,
Fig 4 is a three-dimensional view of a housing without base plate,
Fig 5a
and 5b are three-dimensional cross-sectional drawings of a further embodiment
of the
invention, with the thrust piece lowered in Fig 5a and raised in Fig 5b,
Fig 6a
and 6b are cross-sectional dramngs of further embodiments of the invention.
Fig 7a
and 7b are cross-sectional drawings of further embodiments of the invention.
Fig 8 is a plan view of a region of the contact place in accordance with one
embodiment
of the invention,
Fig 9 is a partial section through a housing in accordance with one embodiment
of the
invention.
Fig 10 is a section through a plurality of housings having a common connection
box.
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WO 91/16738 PCT/GB91/00584
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Fig 11 is a section approximately along the line XI-XI in fig 10.
Fig 11 a
and 1 tb are three-dimensional sections through a further embodiment of the
invention.
Fig 12a
and 12b show the same embodiments of the invention not in section, and
Fig 13 is a three-dimensional view of a housing, partly in section, without
base plate,
according to the embodiment shown in Fig 1 t and 12.
In the following description, essentially three different possible
constructions are described in
detail and. as tar as possible, functionally identical parts bear identical
reference numerals. if
necessary additionally provided with an "a" or a "b° in the case of the
modified embodiments.
For example, the contact element shown in Figures t to 3 is generally
designated t , that
shown in Figures 5a and 5b generally 1 a and that shown in Figures 11 a and 11
b is designated
1 b, to mention but one example.
Referring to the drawings, Figure 1 shows a single contact element, generally
designated , ,
in a so-called exploded view. Considering the drawing from the bottom to the
top, there are
shown, a thrust piece 3, a resilient element 4, a split clamping ring 5, a
screw element 6 and
finally an operating screw head 7 which fits over the screw element.
The contact plate 2 has a lower blade-like slot 8 for cable wires to be
contacted in the housing
Connection to slot 8 may be connected in the factory, or in the field. For
cable wires that are
to be inserted in the field, for connection to those already contacted, or
later to be contacted
by slot 8, an inner through-opening 9 is provided in the contact plate 2. The
through opening
9 is prism shaped having straight sides 9', extending to tapered edges 9"
which taper to a
point 10. A cable wire (designated 11 in Fig 3) is inserted. in use. into
through opening 9.
At its upper end, the contact plate 2 is equipped with a sheet metal vane 12
which is toothed
at both outer edges 13, the teeth being adapted to a screw pitch, i.e. two
corresponding.
substantially mutually opposite teeth exhibit a difference in height that
would correspond to a
screw turn over a sector of a circle.
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WO 91 / 16738 PCT/G B91 /00584
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In order to be fastened in the plastics housing, which is not shown in Fig 1
but is designated
14 in fig 2, the contact plate has two opposite, splayed clamping projections
15. A test
contact vane 16 is formed on at light angles to the phncipal plane of the
contact plate 2, the
free end 17 of which vane 16 lies, in the mounted position, in the intehor of
a test bore
designated 18 in Figure 4 which in use is filled with an insulating gel. For
contacting, a testing
probe is passed through the gel onto the free end 17 of the test contact vane
16 so that a
corresponding measurement can then be taken.
The thrust piece generally designated 3 has an upper guide cylinder 19 having
lateral slots 20
through which the toothed outer edges 13 of the contact plate 2 project in
use, as is shown,
for example, in Fig 2. In the region of transition between the thrust piece 3
and the guide
cylinder 19 which is integrally formed thereon an annular projection 21 is
provided. In use. an
internal thread, not shown in Fig 1, of a screw element 6 fits over the
toothed outer edges 13
in order to create a rotatable, but otherwise fixed, connection between the
thrust piece 3 ano
the screw element 6, the screw element 6 also has an annular projection 22
corresponding to
the annular projection 21 on the thrust piece 3, a split clamping ring 5 being
arranged over the
two annular projections 21 and 22. This may be in the form of a resilient
spring C-shaped
member, or in the form of mating half shells, held together by a mechanical
arrangement. Tne
screw element 6 is additionally equipped with an operating screw head 7
provided with an
inner blind bore, there being provided between the free end, designated 23, of
the guide
cylinder 19 and the base 39 of the blind bore in the operating screw head 7 an
elastic sphng
element 4 so as to be able to act in the direction of the contact in the event
of variations in the
contact pressure, eg due to relaxation of the wire insulation.
Just as the contact plate 2 is provided with a through opening 9 having a
prism shaped
aperture tapering to a point t0 the thrust piece 3 is also equipped with a
corresponding
through-opening 24. This may likewise have a tapered aperture 25 which, in
use. is in register
with the through-opening 9 in the contact plate. In order to prevent the
thrust piece 3 from
turning with the screwing movement of the screw element 6, lateral guide
projections 26 are
provided.
The two screw positions (full unscrewed and full screwed) are shown side-by-
side in Fig 2.
First of all, the plastics housing 14 is equipped with entry apertures 27
corresponding to the
number of contact elements 1, as shown in Fig 4. The through-opening 9 in the
fixed contact
plate 2 which is clamped in the housing 14 is substantially in alignment with
these entry
apertures 27, the latter being larger. however, to allow relative movement of
the inserted
cable wire 11. The through-opening 24 in the thrust piece 3 is exactly in
alignment with the
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opening 9 in the contact plate 2 in the insertion position of a cable wire.
This position is
shown on the right in Fig 2. When the cable wire is then inserted and the
screw element 6 is
fumed by means of the operating screw head 7, the screw element is screwed
downward
over the toothed outer edges 13 of the fixed contact plate 2 together with the
thrust piece 3
in such a manner that an inserted cable wire is squeezed from the top of the
through-opening
24 towards the point 10 of the aperture in the contact plate 2. This position
is shown on the
left if Fig 2.
To open or unmake the contact. the operating screw head 7 is fumed in the
opposite
direction so that the thrust piece 3 is moved upward. Therewith the pinched
cable wire is
lifted by means of the aperture 24 in the thrust piece away from the point 10
of the aperture 9
in the contact plate 2 and can subsequently be withdrawn from the device.
Figures 5a and 5b shows an alternative embodiment of device according to the
invention .
The thrust piece is lowered in Figure 5a to cause contact, and raised in Fig
5b. This
embodiment is similar to that already described with reference to Figures 1 to
4, and like
reference numerals are used to indicate like parts in Figures 1 to 4 and
Figure 5, with the
addition of suffix "a" in Figure 5. Different features in the embodiment of
figure 5 are as
follows. A testing port 41 is provided in cap 7a. To test whether contact has
been made
between an inserted cable wire and the contact plate 2a, a test probe is
inserted into the test
port 41 into electrical contact with the threaded metal insert 6a. The
threaded metal insert is in
electrical contact with the contact plate 2a, and hence the test probe can be
used to check
that electrical contact has been made to the contact plate 2a. Also the spring
4a within the cap
~s a helical spring which lies over a projection 40 extending from the end of
guide cylinder 19a
The projection 40 is of smaller cross-section than the remainder of the guide
cylinder and thus
the spring abuts against the shoulder existing between the projection 40 and
the remainder
of the guide cylinder 19a. In contrast the spring 4 in the cap 7 described
with reference to
figures 1-4 was in the form of a resilient rubber ball. The through opening 25
provided at the
end of the thrust piece is provided in a substantially planar plate 44, which
extends on one
side only of the contact plate. The through opening 25.is, as in Figures 1-4,
in register with
the through opening 9 in the contact plate 2. This arrangement facilitates
withdrawal of a
cable wire, and also facilitates flow of sealing gel around the cable wire.
The contact plate 2
also includes an additional aperture 43 below the through opening 9. This is
to make it easier
for gel to flow within the housing to conform around the cable wire. A final
distinction between
this embodiment and that of Figures 1-4 is that an elongate spring 42
comprising a rod folded-
back on itself into an elongate "U" shape, in the manner of hair grip, is
provided at the bottom
of the thrust piece. Even when the thrust piece 3a has been moved downwards
(by screwing
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WO 91 / 16738 PCT/GB91 /00584
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on insert 6a) so that the internal shoulders 46 of the thrust piece abut and
stop against the
shoulders 45 of the contact plate 2a the elongate spring 42 can be arranged so
that it is
resiliently deformed by a wire (even a small wire) in this configuration, so
that it continues to
exert a downward force on an inserted cable wire. The elongate spring 42 acts
independently
of the spring 4a in cap 7a. Indeed spring 4a is only effective to provide a
constant resilient
force when the wire is of such a size that the thrust piece 3a is not stopped
against the
shoulders 45 of the contact plate.
Figures 6(a and b) and 7(a and b) show alternative arrangements for providing
a continual
pressure on a wire, using a spring which acts independently of any spring in
the cap. In both
figures 6 and 7, the "a" figure illustrates installation of the device onto a
small diameter cable
wire, and the "b" figure illustrates installation of the device onto a large
diameter cable wire. As
before. the devices are similar to devices already described. and therefore
like reference
numerals are used to deschbe like parts. with an "a" suffix applied for
Figures 6 and 7
compared to Figures 1 to 4.
Referring first to Figure 6, the guide cylinder 19 is open at its free end so
that the vane 12a of
contact plate 2a can pass through it, as shown at 50. Also the shoulders 45 on
the contact
plate 2 are lowered relative to those in the embodiments of Figures 1-4. A new
stop is
provided (in place of mating shoulders 45 of the contact plate 2a and internal
shoulders 46 of
thrust piece 3a). The new stop is provided by a plate 51 and support 52 within
the cap which
abuts against the top of the cap 7a. In this embodiment the further spring 52
is provided
between the annular flange 22 of the threaded insert 6a and the annular flange
21 on the top
of thrust piece 3a. When a large diameter cable mre is inserted. (Fig 6b) the
cap is fumed until
the force reaches a certain limit. In this case both the top spring 4 (in the
cap 7) and the further
spring 52 exert a permanent force on the wire. When a small diameter wire is
introduced, (Fig
6a), the cap 7a is fumed until it reaches its physical stop position. ie the
top of the metal vane
12 of contact plate 2a abuts plate 51, and the support 53 abuts the top of the
inside of cap 7
In this position the spring 4a in cap 7a no longer exerts a continuing
pressure. However. in
this position the further sphng 52 is fully compressed and therefore exerts a
continuing
pressure on the small wire. The continuing pressures are desirable in order to
maintain
continuing contact with the cable wires even if relaxaUOn of the wires causes
a change in
pressure in the contact region.
Figures 7a and b are very similar to Figures 6a and b respectively except that
a physical stop is
provided by plate 51 abutting against an internal shoulder 54 in the threaded
insert 6a.
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Figure 8 shows a preferred design of through opening 9 in the contact plate 2.
In this design
the bottom of the opening opens into a narrow slot 60. This design ensures
that for a small
diameter cable wire good contact is achieved by the edges 61 of the through
opening 9, i.e.
those edges between the slot 60 and the main part of the through opening 9.
Preferably the
slot 60 is between 0.1 and 0.45mm wide, preferably about 0.3 mm wide.
The devices shown in Figures 5 to 7 and the preferred feature of Figure 8 can
be used in a
housing as shown in Figures 2-4.
Figure 9 illustrates a preferred housing that can be used. It is shown, in
section, in
conjunction with the device of Figure 5. As before like reference numerals
designate like
parts. Of particular note are the overflow cavity 62 in the housing 4, for
flow of the gel pot
shown) when a wire 11 is inserted. Also lip 63. on the front of the housing,
which acts to
maintain the gel in the housing if the wire 11 is withdrawn. Backstop 64 is
also provided as
part of the housing, to limit the distance of insertion of the wire 11. The
single aperture 25 in
the plate 44 extending at one end of the thrust piece 3, can also be clearfy
seen in this figure.
Figs. 10 and 11 show an assembly of several contacting housings 14 constructed
in modular
form, but the particular configuration shown is merely an example.
Because they are in the form of block modules the contacting housing 14 shown
in Figs. 10
and 11 are designated 14'.
In the example shown, the individual block modules 14' are arranged in a
housing designated
28 overall, a plurality of block modules 14' being screwed to a mounting plate
29. This
mounting plate 29 divides the housing 28 essentially into two regions, the
part comprising the
contact openings 2T being arranged on the side designated 30 of the mounting
plate. whilst
the lower part comprising the contact blades 8 and the insertion slots 31 for
the further cable
wire 11' is arranged on the side designated 32 of the mounting plate 29.
In addition to the mounting plate 29. the housing 28 has a base plate 33 and a
closure
housing 34. the individual elements being pivotally attached to one another by
an optionally
common hinge. as is indicated by broken lines in Fig 10.
In order to provide a reservoir for insulating gel 36 (which is particularfy
desirable where
contact to the blades 8 is to be made in the field rather than in the factory)
corresponding
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WO 91/16738 PCT/GB91/00584
16-
protections are incorporated in the base plate 33. as can be seen from the
cross-section in Fig
11.
A different arrangement for forming a gel reservoir for gel 36 is shown in
Figs 2 and 3. In this
case. a single block module is equipped with a bottom closure cap 37.
Figures 11 to 13 show a further embodiment of device according to the
invention. Figures
11 a and 11 b exhibit the device cut away to reveal the component parts, in
the lowered and
raised positions respectively. Figures 12a and 12b are corresponding
perspective views.
Figure 13 shows the devices of Figures 11a, 11 b, 12a and 12b in a plastic
housing 14b, the
lower part of the housing, which may be filed with gel not being shown in
detail.
As in the previous embodiments a contact plate 2b, and a thrust piece 3b are
provided each
with a corresponding through opening 9b and 25b. However m this case the
relative
movement of the through openings 9b and 25b is achieved by a different
mechanism. In the
previous embodiments the relative movement was provided by screwing a cap
containing a
screw element 6 over toothed outer edges of a vane extending from the contact
plate. In the
embodiment of Figures 11 a to 13 the contact plate does not include such a
toothed vane.
Relative motion of the through openings 9b and 25b is instead provided in the
manner
described below.
An externally threaded driver 65 extends from and is integral with screw head
7b.
Surrounding the driver 65 is a ring Sb with mating internal threads. The ring
5b is provided
wrth external projections 66 Isee Fig 12b) to fix the nng 5b relative to the
housing. Thus as
the screw head 7b is turned, driver 65 is effectively screwed into ring 5b.
and hence moves
axially relative to it and to the housing. The lower end 67 of the driver 65
is arranged to abut
against a cross piece 68 on the thrust piece 3b. Consequently the thrust piece
3b is moved
axially relative to the contact plate 2b and, as before, a cable wire inserted
into through
openings 9b and 24b in the contact plate 2b and thrust piece 3b respectively,
is urged into
contact with the edges of the opening 9b in the contact plate 2b.
As in the previous embodiments. a resilient element 4b may be included. in
this case
between (i) the cross piece 63 of the thrust piece 3b and (ii) the driver
cylinder 65 extending
from the screw head 7b.
The hng 5b is fixed in the plastic housing 14b via a bayonet catch. It may be
turned through
90' so that projections in the form of stop pins 66 fix it in the housing. In
order that the device
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WO 91 / 16738 PCT/G B91 /00584
_17_
1b can be easily mounted in the housing 14b, the housing t4b is provided with
correspondingly shaped slots 69 at the top. Stop pins 66 can therefore be
introduced via the
slots 69 in the housing, and then the elements locked into one another by
turning through
90°.
Also a rod like contact member 16b is preferably included extending up through
the driver
cylinder 60 from the contact plate 2b. This may be used to test for electrical
contact, by
inserting a test probe into contact with member 16b through the screw head 7b.
As in the embodiments of the previous figures, the contact plate 2b is
provided with a lower
blade-like slot 8b for contact leads (not shown) which are to be connected in
the housing. For
contacting the upper cable wires a through-opening 9b is provided in the
contact plate 2b.
This has sloped edges 10b to a point, and an additional lower slot 60b.
When completing the contacting operation an additional axial pressure is
provided by contact
pressure ram 70, extending downward from the cross piece 68 of the thrust
piece 3b. The
free end of this ram 67 may interlock with the contact slot 60, thereby
ensuring that the cable
wires, especially those of small diameter, are contacted securely.
To locate the resilient element 4b in the housing 14b, the contact plate 2b is
provided with
clamping projections 15b, at its lower end.
The clamping projections are bent behind corresponding studs in the housing
14b during
assembly.
Figure 13 shows the embodiments of Figures 11a, 11b, 12a and 12b in a housing
14b. In
particular the figure illustrates the fixed position of the kings 5b in the
housing 14b. It also
illustrates that the individual housing elements are fixed together by click-
stop connections.
as indicated by reference number 71, in figure 13.
The described exemplary embodiments of the invention can, of course. be
further modified in
various respects without departing from the basic concept. For example, the
contact vane 16
may be angled slightly to provide a large support surface for a contact point.
The
corresponding bores 18 for this contact gel may be filled with insulating gel
or may be closed
mechanically, and so on.
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