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(11) | EP 0 263 701 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Electrical terminal fitting |
| (57) In order to provide a simple electrical terminal fitting which enables the insulation
on an insulated wire 8 to be penetrated, contact made, and the connection to be sealed
with contact sealant in one operation, a metal terminal 2 has facing cutting edges
3; a push-on cap 4 has a hole 7 through which the wire is threaded; subsequent to
threading the wire, the cap 4 is pushed home and projections 9,10 guide the cap 4
and also provide a snap fitting by engaging in slots with suitable enlargements.
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BACKGROUND OF THE INVENTION
[0001] The present invention relates to an electrical terminal fitting for connecting an insulating wire to an electrical terminal which has a cutting edge, the fitting comprising a push contact support having two spaced engagement parts which will pass on either side of the terminal cutting edge, the engagement parts being arranged to engage the insulated wire while pushing the contact support home and being positioned so that as the contact support is pushed home, the engagement parts push the wire against the terminal cutting edge so that the edge cuts through the insulation of the wire and engages the wire conductor, guide means for guiding the motion of the contact support as it is pushed over the terminal so that the wire is correctly positioned in relation to the terminal cutting edge, and retaining means for retaining the contact support in position with the cutting edge engaging the wire conductor. It is desirable to provide such fittings so that the connection can be made without using any tools, and also so that the connection can be made without needing great skill and so can be made in awkward locations or by less skilled workers; it is also desirable that the connection should be made quickly. All these desiderata must however be consistent with the formation of a good electrical connection which, under normal conditions of use, will not become disconnected.
[0002] The possibility of making a terminal connection with an insulated wire without removing the insulation is known. GB-A-2 117 190, GB 1 535 159 and EP-A1 0 079 722 all show a terminal having a reentrant or slit and opposed cutting edge between which the wire is pushed. All these are relatively complicated and are not particularly suitable for holding a sealant.
THE INVENTION
[0003] The present invention provides an electrical terminal fittings as set forth in Claim 1 and a method as set forth in Claim 11. The remaining Claims set forth optional features of the invention.
[0004] The cap preferably is of rectangular or square section. The cap may be filled to a suitable level with contact sealant to seal the connection, making encapsulation unnecessary and also enabling the connection to be dismantled; a particular advantage of this is that the amount of sealant is low so that expensive proprietary sealants can be used without great overall cost. Alternatively however the sealant can be inserted after pushing on the cap, for instance by injecting through a hole in the end of the cap, or normal encapsulation can be carried out, for instance again using a hole in the end of the cap.
[0005] The invention provides a fitting which is capable of cutting the insulation and terminating wire of thin section. The wire is guided onto the cutting edge of the terminal.
[0006] The guide means may simply be a sliding fit between the cap and the terminal or a part associated with it, or even an arrangement of the terminal itself which engages the wire and ensures that the wire passes correctly down the cutting edge. Preferably however the guide means is as set forth in Claim 10.
[0007] The retaining means may be a simple friction fit to ensure that the cap does not fall off. Preferably however the retaining means is a snap fitting - the user by finger pressure senses when the cap is fully home.
[0008] In a preferred arrangement, at least one of the retaining parts is a hole, through which the wire can be passed before pushing on the cap, and the skill required for connecting the wire to the terminal is very low, enabling connections to be made in awkward locations or by less skilled workers. All that is necessary is to thread the wire through the hole and push the cap home with finger pressure, and in a single operation, the insulation of the wire is penetrated and the contact made. The operation can be carried out without using any tools - this is significant particularly if the item of electrical equipment concerned is itself an electrical connector which does not require tools for making other connections - such a connector is described in GB-A-2 173 653 or EP-A-0 196 925.
[0009] Although the engaging parts can for instance be registering holes, they are preferably as set forth in Claim 4. As the wire can be sealed where it enters the cap, the wire can be totally encapsulated. In other words, the wire does not project through to the other side, and does not leave a bare end which needs to be sealed; the bare end of the wire is within the cap, which in itself affords it some protection; if sealing is required, this can simply be accomplished, for instance using contact sealant or normal encapsulation.
[0010] If the arrangement is as set forth in Claim 5, when moulding the cap, one can avoid the requirement for having two core pins for forming holes; it is only necessary to use a single, relatively short core pin.
[0011] The invention will be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is an front view of two units of a terminal block with electrical terminal fittings of the invention;
Figure 2 is a side view of one of the units, as seen looking along the line II in Figure 1;
Figure 3 is an isometric, partly schematic view of one of the units;
Figure 4 is an isometric view of the terminal strip of Figure 3 (seen from the other side);
Figure 5 is a plan of the cap of Figures 1 to 3, on a larger scale, showing the open end;
Figure 6 is an isometric view of the underside of the cap of Figure 1;
Figures 7 and 8 correspond to the lower part of Figure 2 and to Figure 5, showing two modifications;
Figure 9 is an isometric view of a second embodiment of the invention; and
Figure 10 is an isometric view of a third embodiment of the invention.
Figures 1 to 6
[0012] Figures 1 to 3 show a terminal unit 1 generally as shown in Figure 3 of GB-A-2 173 653 (referred to above), which can be included in a stack of similar units held together with rods, generally as shown in Figure 4 of GB-A-2 173 653. The unit 1 is an electrical connector for making connections in telecommunications networks without using any tools. Reference can be made to GB-A-2 173 653 for a general description and details.
[0013] The unit 1 has a terminal 2 in the form of a rectangular-section metal strip of for instance berylium copper. The open end of the strip 2 is formed with an open two-edged cutting jaw by means of a reentrant or slit, the sides of which form facing cutting edges 3 (see Figure 4).
[0014] A separate contact support or cap 4 can be pushed rectilinearly onto the terminal 2 by finger pressure - the cap 4 can be very small, the head 5 for instance being a rectangle of 13 × 8 mm. The cap 4 has a rectangular-section or box-section skirt 6 which provides two, spaced wire-engagement parts which will pass on either side of the terminal cutting edge 3, and which are on opposite sides of the skirt 6 One of these parts defines or is formed by a hole 7 through which an insulated wire 8 can be passed before pushing on the cap 4. The hole 7 registers with a recess in the form of a slot 7ʹ which is open upwards (see Figure 5). The slot 7ʹ provides a base 7ʺ upon which the wire 8 can rest, for retention and thereby forming the other engagement part, and an abutment face 7ʹʺ for engaging the end of the wire 8 and preventing the wire 8 being pushed right through.
[0015] In moulding, a core pin will be required for making the hole 7. However, the slot 7ʺ can be made by a blade-shaped projection on the core which forms the central recess 4ʹ in the cap 4.
[0016] When the cap 4 is pushed fully home, the skirt 6 surrounds the terminal 2. As the cap 4 is pushed on, the cutting edges 3 cut through the insulation of the wire 8 and engage the wire proper.
[0017] In order to ensure that the cap 4 is positioned correctly, and hence the wire 8 is positioned correctly in relation to the cutting edges 3, there are guide means. The cap 4 has two projections 9,10 on one side (see Figure 2) and one or two projections 11,11ʹ on the other side (Figure 2 shows two while Figure 7 shows one). In each pair, the projections 9,10 or 11,11ʹ are on either side of the position to be occupied by the wire 8. These projections 9,10,11,11ʹ engage in respective slots 12 (see Figure 1) which are defined between cooperating faces of adjacent terminal units 1. The projections 9,10,11,11ʹ and slots 12 also provide a snap fitting for retaining the cap 4 in position with the terminal cutting edge 3 engaging the wire 8 proper. For this purpose, at least the slot that is entered by the projections 9,10 has two enlarged portions 13 (the other slot will have one or two enlarged portions 13 for accommodating the projections 11,11ʹ). In this way, the cap 4 can be locked in position on the respective terminal unit 1.
[0018] The cap 4 can be pre-filled with a metered amount of contact sealant 14 (indicated in Figure 2), which would normally be a grease. As an alternative, a hole 15 (shown dashed in Figures 5, 6 and 8) may be formed in the head 6 of the cap 4 and sealant (e.g. a sealant jelly) injected later. As a further alternative, the hole 15 can be used for injecting an encapsulating resin such as an epoxy or polyurethane resin.
Figures 7 and 8
[0020] Figures 7 and 8 show that the retaining parts can define two registering holes 7. The wire 8 is pushed through both holes 7 before pushing on the cap 4.
Figure 9
[0021] Figure 9 shows that the terminal 21 can be of U-shape with double cutting edges 3 on each end and engaged by two caps 4, to provide a simple wire-in wire-out facility.
Figure 10
1. An electrical terminal fitting for connecting an insulated wire (8) to an electrical
terminal which has a cutting edge (3), the fitting comprising a push contact support
(4) having two spaced engagement parts (7,7ʺ or 7,7) which will pass on either side
of the terminal cutting edge (3), the engagement parts (7,7ʺ or 7,7) being arranged
to engage the insulated wire (8) while pushing the contact support (4) home and being
positioned so that as the contact support (4) is pushed home, the engagement parts
(7,7ʺ or 7,7) push the wire (8) against the terminal cutting edge (3) so that the
edge (3) cuts through the insulation of the wire (8) and engages the wire conductor,
guide means (9,10,11,11ʹ,12 or 9,10,11,12) for guiding the motion of the contact support
(4) as it is pushed over the terminal (3) so that the wire (8) is correctly positioned
in relation to the terminal cutting edge (3), and retaining means (13) for retaining
the contact support (4) in position with the cutting edge (3) engaging the wire conductor,
characterised in that the contact support (4) is in the form of a cap for containing
contact sealant (14), the cap (14) having a skirt (6) which surrounds the terminal
(2) when the cap (4) is pushed fully home, the engagement parts (7,7ʺ or 7,7) being
on two opposite sides of the skirt (6).
2. The terminal fitting of Claim 1, wherein the engagement parts (7,7ʺ or 7,7) retain
the wire (8) prior to pushing on the cap (4).
3. The terminal fitting of Claim 1 or 2, wherein at least one of the engagement parts
(7) defines a hole (7) through which the wire (8) can be passed into the interior
of the skirt (6) before pushing on the contact support.
4. The terminal fitting of any of the preceding Claims, wherein a second of the engagement
parts (7ʺ) is associated with a face (7ʺʹ) which engages the end of the wire (8),
prevents the end of the wire (8) exiting from the other side of the cap (14), and
blanks off the end of the wire (8) from the other side of the cap (14).
5. The terminal fitting of Claim 4, wherein the other engagement part (7ʺ) defines
a support ledge (7ʺ) on which the end of the wire (8) can rest and which is adjacent
to said face (7ʺʹ), which is a face against which the end of the wire (3) will abut.
6. The terminal fitting of any of the preceding Claims, wherein the terminal end portion
has a reentrant, the sides of which form facing cutting edges (3,3), the cap (4) being
arranged to push the wire (8) in between the cutting edges (3,3).
7. The terminal fitting of any of the preceding Claims, wherein the contact support
(4) is a separate push-on member and the guide means (9,10,11,11ʹ,12 or 9,10,11,12)
guide the contact support substantially rectilinearly.
8. The terminal fitting of any of the preceding Claims, wherein the cap contains contact
sealant (14).
9. The terminal fitting of any of the preceding Claims, wherein the retaining means
(13) is a snap fitting (13).
10. The terminal fitting of Claim 9, wherein the guide means comprise at least one
projection (9,10,11,11ʹ or 9,10,11) on the side of the contact support (4), which
projection enters a slot (12) adjacent the terminal and also provides the snap fitting.
11. A method of attaching an insulated wire (8) to an electrical terminal (2), comprising
using the terminal fitting of any of the preceding Claims by engaging the wire (8)
with and retaining the wire (8) by the contact support (4) and then pushing on the
cap (4) so that the terminal (2) cuts through the insulation of the wire (8) and engages
the wire proper, the cap (4) being retained in position with the terminal (2) engaging
the wire (8) proper.
12. The method of Claim 11, wherein a contact sealant or encapsulant (14) is inserted
into the cap (4) after the cap (4) has been pushed home and retained in position.