Note: Descriptions are shown in the official language in which they were submitted.
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wo 92naz~~ ~CT/GB92/00230
This invention relates to an electrical crimp connector for
connecting two or more elongate electrical conductors.
Hitherto, electrical crimp coruiectors have been proposed which
have sought to prevent corrosion of the metal exposed within them by
various means. These means have tended either to be unsuccessful or
time consuming and requiring the use of specialised equipment to
produce the necessary protection. For example, the use of grease to
prevent water contacting the exposed metal of the connection involves
the risk that the grease may be easily dislodged, or indeed that the
action of crimping may force the grease out of the connection. One
successful method of providing a good seal against corrosion is the use
of a heat-recoverable sleeve containing a hot-melt adhesive, the sleeve
being heated to seal the device after crimping, but this method is more
time consuming than one which merely involves crimping actions.
~0 Furthermore, the use of heat may be inappropriate in certain cases.
According to one aspect, the present invention provides a device
for forming a butt splice between two or more elongate electrical
conductors, which comprises a crimp barrel having two open ends, an
electrically insulating sleeve located about and extending beyond the
end~ of the crimp barrel, and a quantity of gel located within each end
region of the insulating sleeve beyond each end of the crimp barrel for
~'O 92/14278 PCT/GB92/002
~~.~fl~~~ -2-
sealing each end of the splice against ingress of moisture, each
quantity of gel containing an aperture to allow the insertion of one or
mare elongate electrical conductors into each end of the crimp barrel. ,
The present invention has the advantage that it provides a
device which is relatively simple to employ in the production of an
essentially corrosion resistant connection between two or more
elongate electrical conductors, involving only the action of crimping to
farm and seal the connection. The invention allows the conductors to
be located v~ithin the crimp barrel with little disturbance of the gel
material. Thus, it is possible to form a splice that has a relatively low
contact resistance due to the absence of gel between the conductors and
the crimp barrel. Furthermore, the absence of gel from the crimp
barrel means that the conductors may be inserted and located more
1.5 easily and any tendency of the conductors to be forced out of the crimp
barrel before or during crimping is reduced.
According to a preferred feature of the invention, the device
includes a ferrule (in the form of a hollow cylinder or ring) located
beyond each end of the crimp barrel, between the insulating sleeve and
the gel. These ferrules may provide a number of advantages. For
example, they may protect the elongate electrical conductors inserted
into the device from strain arising from their movement (referred to
hereafter as strain relief). Alternatively, or additionally, the ferrules
may contribute to the environmental sealing of a splice formed with
the device by being capable of being crimped in order to compress at
least part of the gel against an electrical conductor inserted into the
crimp barrel. Thus, the invention also provides a device for forming a
butt splice between two ar more elongate electrical conductors, which
comprises a crimp barrel having two open ends, an electrically
insulating sleeve located about and extending beyond the ends of the
crimp barrel, a quantity of gel located within each end region of the
insulating sleeve beyond each end of the crimp barrel for sealing each
end of the splice against ingress moisture, and a ferrule located
beyond each end of the crimp barrel between the insulating sleeve and
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. WO 92/14278 f'CT/GB92/pU210
-3-
the gel, each ferrule being capable of being crimped in order to
compress at least part of the gel agfainst an electrical conductor
inserted into the crimp barrel and/or to provide strain relief for the
electrical conductor.
The electrically insulating sleeve of the device provided by the
invention preferably comprises a cross-linked polymeric material,
such as, for example polytetrafluoroethylene, ethylene
tetrafluoroethylene or polyvinylidine fluoride. More preferably
however, the sleeve comprises a nylon material such as nylon S or
nylon 11, but especially nylon 12.
In some cases it may be desirable for each end of the insulating
sleeve to have an inwardly curved edge portion that leaves an aperture
that will allow the insertion of one or more elongate electrical
conductors therein but will hinder the exudation of gel from the sleeve,
both prior to and during the use of the device.
It has been found that for certain elongate electrical conductors,
such as, for example some single copper wires, it is advantageous for
the crimp barrel to have an internal profile that is capable of gripping
them. For example, the inside of the crimp barrel may contain teeth,
barbs or gripping edges which can help to strengthen a connection
formed by the device. However, for certain other elongate electrical
conductors, such as for example some mufti-stranded copper wires,
no advantage is necessarily gained from the crimp barrel containing
teeth, and a smooth internal profile may be sufl'acient to form a strong
connection (once the device has been crimped).
It is preferable for the crimp barrel to be formed from an
electrically conductive material, such as copper for example. i~Vhere
tin-plated elongate conductors are to be connected, it is highly
desirable for the crimp barrel to have an internal surface of tin, such
as with a tin-plated copper crimp barrel, so as to reduce the risk of
galvanic corrosion.
WO 92/14278 Pcric~~iiaaay:.
w ...
The device according to the invention includes a quantity of gel , i
located within each end region of the insulating sleeve beyond each
end of the crimp , barrel for sealing each end of the splice against
ingress of moisture. The term 'gel' as used herein is intended to ;
mean a liquid-extended polymer composition. Such compositions
normally contain a three-dimensionail network of cross-linked
molecular chains and preferably include at least 300 parts, more
preferably at least 500 parts by weight of extender liquid per 100 parts
by weight of the polymer composition. The gel used in the invention
preferably has a cone penetration value (measured by ASTM D217)
within the range of from 100 to 400 10-1 millimetres, more preferably
100 to 350 10-1 millimetres; an ultimate elongation (measured by ASTM
D412) preferably greater than 100%, with substantially elastic
deformation to an elongation of preferably at least 100%; and ultimate
tensile strength (ASTM D412) preferably less than 1 MegaPascal.
The polymer composition may for example comprise an
elastomer, or a block copolymer having relatively hard blocks and
2D relatively elastomeric blocks. Examples of such copolymers include
styrene-diene block copolymers, for example styrene-butadiene or
styrene-isoprene diblock or triblock copolymers, or styrene-ethylene-
butylene-styrene triblock copolymers as disclosed in international
patent application number PCT/GB87/00506. The extender liquids
employed in the gel preferably comprise oils conventionally used to
extend elastomeric materials. The oils may be hydrocarbon oils, for
example paraflinic or naphthenic oils, synthetic- oils for example
polybutene or polypropene oils, and mixtures thereof. The preferred
oils are mixtures of non-aromatic paraffins and naphthenic
hydrocarbon oils. Suitable gels can also be prepared by curing reactive ~ .
silicones with non-reactive extender silicones. The gel may contain
known additives such as moisture scavengers (eg. benzoyl chloride), v
antioxidants, pigments and fungicides.
g
WO 92114278 ~ ~ ~ ~ ~ ~) 7 PCT/GB92/00210
_5_
The function of the gel in the device according to the invention is
to seal it from moisture ingress once the elongate electrical conductars
which are required to be spliced, have been inserted into the crimp
barrel and crimped. This is best achievs;d by applying pressure to the
gel, since in this state it behaves in a ananner similar to a liquid, in
that it is capable of flowing and conforming around intricate shapes
and adhering to solid surfaces.
In a preferred embodiment of the invention the ferrules, located
beyond each end of the crimp barrel between the insulating sleeve and
the gel, are capable of being crimped about each elongate conductor
inserted therein. This may have the advantage of increasing the
capability of the ferrules to provide strain relief to the elongate
conductors. Additionally or alternatively, crimping the ferrules about
lu the conductors can have the effect of compressing the gel, and hence
may aid the sealing of the device. In a particularly preferred
embodiment of the invention, at least a portion of each quantity of gel is
located between its corresponding ferrule and the crimp barrel. When
this device is crimped in the regions of the crimp barrel and each
female, each portion of gel located between a ferrule and the crimp
barrel will normally be compressed (depending upon the degree of
crimping and the total cross-sectional area of the insulated conductors
inserted into each end of the device). 'rVhen the gel is compressed, it '
'wets' the inner surface of the insulating sleeve and the outer surfaces
Z5 of the insulated conductors, sealing the splice from moisture ingress.
In addition, the ferrules themselves, together with any gel located
beyond the ferrules at each end of the device, may also serve to protect
the splice from foreign matter such as dirt etc.
In order to ensure a secure, sealed connection, the crimp barrel
and the ferrules may be fixed in position within the device. This may
be achieved by, for example, bonding the crimp barrel and the ferrules
to the internal surface of the insulating sleeve. In particular, the
inside of the sleeve may be coated with a layer of adhesive. Adhesives
that may be employed include hot melt adhesives, eg. those based on
wo ~znaz~s pcric~~ziooz ~-
ethylene homo or copolymers, eg. ethylene vinyl acetate or ethylene ,
ethyl acrylate, and polyamide adhesives, for example formed from ~ ,
polyamides having a
relatively large number (eg. >15) of carbon atoms between adjacent
carbonyl groups, preferred polyamides being based on dimer diamines
as described in US patent Nos. 4,018,733 and 4,181,775.
According to another aspect, the invention provides a method of
forming a butt splice between two or more insulated elongate electrical
conductors by means of a device which comprises a crimp barrel
having two open ends, an electrically insulating sleeve located about
and extending beyond the ends of the crimp barrel, and a quantity of
gel located within each end region of the insulating sleeve beyond each
end of the crimp barrel for sealing each end of the splice against
ingress of moisture, each quantity of gel containing an aperture to
allow the insertion of one or more elongate electrical conductors into
each end of the crimp barrel, the method comprising:
(i) stripping a length of insulation from the end of each
conductor;
(ii) inserting one or more of the conductors into each end of
the device so that the end of each conductor extends into
the crimp barrel and a portion of the insulation is
surrounded by the insulating sleeve; and
(iii) crimping the crimp barrel about the conductors. '
When the device contains a crimpable ferrule located beyond
30 each end of the crimp barrel between the insulating sleeve and the gel,
the method includes a further step:
(iv) crimping each ferrule about the insulation of each
conductor inserted therein.
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. ~0 9zim2'8 ~crics~ziooz~o
_7_
Because the gel material is deforxnable, it is often possible for
one or both quantities of gel in the device to have an aperture cross-
sectional area that is smaller than the combined cross-sectional area
of each insulated conductor inserted therein. This can be
advantageous, since the act of inserting the conductors into the device
may compress the gel between the conductors and the internal surface
of the device, and crimping preferably reinforces this compressive
action, enhancing the moisture seal.
IO The device according to the invention will now be described by
way of example with reference to the accompanying drawings in
which:
Figure 1 is a sectional elevation along the axis of a device
according to the present invention and a pair of insulated
wires; and
Figure 2 is a sectional elevation along the axis of a butt splice
between two insulated wires formed by the device of figure I.
Referring to Figure 1, a device 1 for forming a butt splice
between two (or more) electrically insulated cables 2 c~mprises a
crimp barrel 3, an electrically insulating sleeve 4 located about and
extending beyond the ends of the cramp barrel (the diameter of the
sleeve beyond each end of the crimp barrel being greater than that in
the region located about the crimp barrel), a quantity of gel 5 located
within each end region of the insulating sleeve beyond each end of the
crimp barrel, two ferrules 6, located beyond each end of the crimp
barrel between the insulating sleeve and the gel and a layer of
adhesive 7 coated onto the internal surface of the insulating sleeve to
bond the crimp barrel and the strain relief ferrules in place. The
crimp barrel 3 contains teeth 8 for gripping the bare ware 9 of each of
the two insulated cables 2 and thus forming an electrical contact
between them. Each quantity of gel contains an aperture 10 to allow
the insertion of the cables into the device. The diameter of each gel
i
WO 92/14278 PCTIGB92/002
- s - ~'
aperture 9 is shown to be smaller than the diameter of the insulation
of the wire to be inserted into it, to illu.stra~te the fact that because of
its ~ i
deformable nature, the gel 5 is able to allow the insertion of the
insulated wire.
i
Figure 2 shows the completed splice between the two cables of
Figure 1, formed by the cables having been inserted into the device of - _
Figure 1, and the device being crimped in the regions shown by the
arrows. The two quantities of gel 5 are seen to be compressed in the
region 11 between each ferrule 6 and the crimp barrel 3, thus sealing
the electrical contacts from moisture. Furthermore, each of the
ferrules, together with the outermost portions of gel 12 serve to
increase the degree of protection of the splice, particularly from
foreign bodies such as dirt.
