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The present invention relates to an electrical terminal.
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Insulated terminals are well known, for example, for audio applications. Such terminals are mounted on, or incorporated in, panels of devices to enable connections to be made simply to the device.
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For safety, new legal requirements are being introduced requiring the electrical connectors of such terminals to be "touch-proof" in certain circumstances. This means that the terminals need to be constructed such that the connector is not generally accessible, for example, to a user's finger.
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GB-A-2270209 describes an electrical terminal comprising an hollow, insulating housing, an elongate electrical connector having one part thereof extending through the housing and a connection region located within the housing, and an insulating cover carried by said one part of the electrical connector and arranged to surround the one end of the electrical connector defined by the end of said one part, said insulating cover being longitudinally movable with respect to said electrical connector between a first position, in which the cover is received within said hollow housing and substantially surrounds said connection region of the connector, and a second position, in which the cover is withdrawn from said connection region and with respect to said hollow housing, wherein means are provided to enable access from externally of the housing to said connection region when the insulating cover is withdrawn to its second position.
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In this arrangement, access to a connection hole in the connection region for receiving a wire is through an aligned hole in the insulated terminal housing.
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Whilst the terminal shown in GB-A-2270209 probably meets the newly required standards by making the electrical connector inaccessible to a standard test finger, it is of limited use. In this respect, access for the test finger is denied because the hole in the housing is restricted to the size of the connection hole in the connector. However, whilst the arrangement denies access to the connector by the test finger, it also denies access to wires which are not of, or smaller than, a predetermined size. The known terminal also prevents the connection thereto of wires with terminations, for example, having spade adaptors or spade terminals attached thereto.
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It is an object of the present invention to provide an electrical terminal which reduces the disadvantages of a terminal of the prior art.
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According to a first aspect of the present invention an electrical terminal of the type defined above is characterised in that said access means comprise a slot provided in said hollow housing, and in that said slot is shaped to provide first and second areas, the first area being of restricted width as compared to the second area.
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There is, of course, a conflict between denying access to the connector for safety reasons, and enabling access to it by more than one size of wire, by other wire terminations, and by connectors. Thus, access for a number of different wires, and for a number of different wire terminations may be straightforwardly achieved by providing in the housing a rectangular opening having dimensions at least equalling the maximum dimensions of the wires or their terminals to be accommodated. This, of course, leads to the provision of a large size rectangular slot which is likely to fail to meet the standards for "touch-proof" terminals. The solution adopted by GB-A-2270209 to the problem of providing a "touch-proof" terminal is to choose but a single use for the connector, that is, connection thereto by one size of wire and then to provide a hole in the housing of substantially the same size so that the selected wire may be connected to the connector, but access is denied to anything larger.
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A connector of an embodiment of the present invention has a shaped slot providing first and second areas of differing widths. The provision of two areas each of differing dimensions enables each area to be designed to enable access to a particular size of wire, to a particular type of wire termination, or to a particular type of connector. The embodiment of the invention therefore increases the accessibility of the connector to wires and wire terminations of differing types and sizes. However, and importantly, this increase in accessibility is achieved without a corresponding increase in the accessibility of the connector to a test finger.
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In a preferred embodiment, the slot is shaped to provide a first area for passage of a wire therethrough, and a second area for the passage of a spade termination therethrough.
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In an embodiment, the slot opens into the upper surface of the housing.
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In a particularly preferred embodiment, the slot in the housing is in the shape of a substantially inverted T. In this embodiment, the upright of the T may be sufficiently wide to allow the passage therethrough of a wire of a predetermined diameter, whilst the base of the T may be wide enough to enable access to a spade terminal but is restricted in depth.
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The connection region of the electrical connector may be arranged to facilitate the connection thereto of any required wire or wire termination. For example, a substantially cylindrical bore may extend through the connection region of the electrical connector substantially transversely to the longitudinal extent thereof. As is common, the transverse dimension of the connector at the connection region may be increased to contain the bore. Additionally and/or alternatively grooves may encircle the connection region and/or one or more waisted areas may be provided therein to facilitate the connection thereto of spade adaptors and terminals and any other required wire terminations.
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In a preferred embodiment, said one part of the connector is provided with an external screw thread which is engaged with an internal screw thread of said insulating cover. Longitudinal movement of said insulating cover relative to the electrical connector can then be achieved by rotation of the insulating cover. Preferably, said external screw thread extends to the free end of said one part.
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At its free end the insulating cover may carry a cap for facilitating its rotation. For example, the cap may be hexagonal for engagement by a spanner or other tool and/or may include a slot for engagement by a coin, screwdriver or other tool.
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Preferably, when the insulating cover is in its first position received within the housing it is arranged to cooperate with the housing to clamp the wire or wire termination and to keep the terminal tight. This function of the insulating cover is enhanced if tools are used for its rotation to tighten its engagement.
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In an embodiment, the hollow housing is provided with an annular flange or shoulder on which the insulating cover engages in its first position.
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The electrical connector preferably comprises said connection region arranged intermediate said one part and a second part. The second part is preferably engaged with, and projects through, the base of said hollow housing. Said second part of the connector may be provided with a solder tag, solder bucket, or other solder terminal or may be provided with a number of such solder terminals.
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The terminal of the invention is arranged to be mounted on a mounting panel. In a preferred embodiment, the electrical terminal is mounted onto a base moulding which may be clamped by suitable means to the mounting panel or may be formed within the mounting panel.
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In a preferred embodiment, the base moulding has a bore therethrough through which the second part of the electrical connector may extend, the bore having a widened part receiving a cylindrical extension on the base of the hollow housing. Preferably, said cylindrical extension is received within the bore in the base moulding to define therewith a single through bore for the electrical connector. In a preferred embodiment, said through bore is internally screw threaded for engagement with an external screw thread on said second part of the connector.
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In a preferred embodiment, a multiple electrical terminal is provided comprising a base moulding carrying a number of individual electrical terminals as defined above, wherein cooperable engagement means are carried by the base of the hollow housing of each individual terminal and by said base moulding for engaging each said housing on the base moulding.
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Preferably, the cooperable engagement means are additionally arranged to orientate each housing on the base moulding. This enables the housings to be mounted, for example, such that their slots face in differing directions. This is particularly important if wires with terminations, for example, such as spade adaptors, are to be connected to more than one of the terminals on the base moulding.
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In one embodiment, the cooperable engagement means comprise a key on each housing arranged to engage in a selected one of a number of keyways therefor provided on the base moulding.
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The present invention also extends to a multiple electrical terminal comprising a base moulding carrying a number of individual terminals, wherein each individual terminal comprises an hollow, insulating housing, an elongate electrical connector having one part thereof extending through the housing and a connection region located within the housing, and an insulating cover carried by said one part of the electrical connector and arranged to surround the one end of the electrical connector defined by the end of said one part, said insulating cover being longitudinally movable with respect to said electrical connector between a first position, in which the cover is received within said hollow housing and substantially surrounds said connection region of the connector, and a second position, in which the cover is withdrawn from said connection region and with respect to said hollow housing, wherein a slot is provided in said hollow housing and is arranged to enable access from externally of the housing to said connection region when the insulating cover is withdrawn to its second position, and further comprising cooperable engagement means carried by each said housing and by said base moulding for engaging each housing on the base moulding.
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Preferably, the cooperable engagement means are additionally arranged to orientate each housing on the base moulding. This enables the housings to be mounted, for example, such that their slots face in differing directions. This is particularly important if wires with terminations, for example, such as spade adaptors, are to be connected to more than one of the terminals on the base moulding.
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In one embodiment, the cooperable engagement means comprise a key on each housing arranged to engage in a selected one of a number of keyways therefor provided on the base moulding.
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Each individual terminal of a multiple electrical terminal as defined above may have selected ones of, or all of the features of electrical terminals as defined above.
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Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:
- Figures 1a and 1b show perspective views of an electrical terminal of the invention, Figure la showing an insulating cover of the terminal in its inserted position, and Figure 1b showing the insulating cover when withdrawn,
- Figures 2a and 2b show end elevations of the electrical terminal of Figures 1a and 1b with the insulating cover, in its two positions,
- Figures 3a and 3b show longitudinal sections through the electrical terminal shown in Figures 2a and 2b,
- Figure 4 shows a multiple electrical terminal having two individual terminals as shown in Figures 1 to 3,
- Figure 5 shows a multiple electrical terminal having four individual terminals as shown in Figures 1 to 3,
- Figure 6 shows a plan view from above of the two terminal multiple electrical terminal of Figure 4 showing the connection to one of the individual terminals of a spade adaptor,
- Figure 7 shows an alternative embodiment of a multiple electrical terminal having two individual terminals as shown in Figures 1 to 3, and
- Figure 8 shows an alternative embodiment of a multiple electrical terminal having four individual terminals as shown in Figures 1 to 3.
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An embodiment of an insulated terminal 10 of the present invention is shown in Figures 1 to 3. The terminal 10 comprises an insulating hollow housing 12, for example, of a plastics material through which a metal electrical connector 14 extends. The housing 12 is mounted onto a base moulding 16. An internally threaded through bore 18 (Figures 3a and 3b) extends through the base of the housing 12 and the base moulding 16 and an external screw thread of the connector 14 is engaged therewith to fix the connector 14 relative to the housing 12. The base moulding 16 may be mounted onto a mounting panel (not shown) by a nut as 20. Alternatively, the base moulding 16 may be integrated in a mounting panel. At its lower free end the connector 14 is provided with an appropriate termination, for example, a solder termination which may be a solder tag, or a solder bucket. In the embodiment illustrated, the connector 14 has both a solder bucket 21 and a solder tag 22 (Figures 1a and 1b).
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In the embodiment illustrated, the base of the housing 12 has a cylindrical extension 24 which is received within a widened part of a bore 26 of the base moulding 16. It will be clear from Figures 3a and 3b that the cylindrical extension 24 and the bore 26 cooperate to define the single through bore 18 for the electrical connector 14. In addition, and as will be described below, the cylindrical extension 24 acts as a key and the widened part of the bore 26 acts as a keyway for orientating the housing 12 relative to the base moulding 16.
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The electrical connector 14 is substantially conventional and has a first, externally threaded, elongate part 30 coupled to a second, externally threaded, elongate, lower part 32 by way of an intermediate connection region 34. The connection region 34 is substantially cylindrical and has a part of enlarged diameter as compared to that of the first and second parts 30 and 32. A substantially cylindrical through bore 36 extends through the enlarged diameter part of the connection region 34 for the receipt of a stripped wire end in known manner. The connection region 34 also comprises a waisted part 38 of reduced diameter which has a substantially smooth, external cylindrical surface. A spade connector or adaptor (not shown) may be engaged around this waisted part 38 to make connection with the connector 14.
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To insulate the connector 14 the terminal 10 is provided with an insulating cover 40 cooperating with the hollow housing 12. This cover 40 is substantially cylindrical in shape and has a longitudinally extending bore 42 therethrough. A metal insert 44 is mounted in the bore 42 of the cover and is internally screw threaded to engage with the external screw thread on the first elongate part 30 of the connector 14. It will be appreciated that rotation of the cover 40 relative to the connector 14 will cause the cover 40 to move longitudinally with respect to the connector 14. The cover 40 is movable between a first, inserted position which is shown in Figures 1a, 2a and 3a and a second, withdrawn position which is shown in Figures 1b, 2b and 3b. It can be seen in Figure 3a that, in the inserted position, the bottom surface of the cover 40 engages an annular flange 46 formed within the hollow housing 12. In that inserted position of the cover 40, the first elongate part 30 and the connection region 34 of the connector 14 are substantially completely insulated by the housing 12 and the cover 40. When the cover 40 is withdrawn to its second position, as shown in Figures 1b, 2b and 3b, the connection region 34 becomes accessible by way of a slot 50 formed in the housing 12.
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As can be seen from the drawings, the slot 50 is substantially in the form of an inverted T. As is clear from Figure 2b, the upright of the T slot 50 has a width which is substantially equal to the diameter of the bore 36, and it will be appreciated that this allows the passage therethrough of a wire (not shown) for insertion in the bore 36. The base of the T slot 50 is substantially wider than the upright thereof, but is very restricted in depth. The base of the T slot 50 allows access to a spade terminal (not shown) to be engaged around the waisted region 38 of the connector.
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In use, the insulating cover 40 is withdrawn to its position shown in Figures 1b, 2b, 3b, to enable connections required to be made to the connector 14. Thereafter the cover 40 is returned to its inserted position where it also serves to grip or clamp any wire or terminal engaged with the connector 14. To aid the cover in its gripping or clamping function a cap 60 is fixed to its upper end. This cap 60 is hexagonal in shape and is also slotted. The cap 60 facilitates the use of a tool such as a spanner or a screwdriver (not shown) to rotate the cover 40. Therefore, the rotation of the cover 40 to its tightened inserted position can be made by a tool and thus the gripping or clamping action can be made more effectively than if the cover 40 were rotated by fingers only.
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As is common with insulated terminals, the free upper end of the connector 14 is provided with a tapped and screwed socket indicated at 62 for the receipt of a spigot plug if required. If such a plug is not to be used an insulating plug member 64, indicated in Figure 2a, may be inserted within the cap 60 of the cover 40 to deny access into the terminal from its top.
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It will be appreciated that in the inserted position of the cover 40, the cover 40 and housing 12 cooperate to enclose and insulate the first part 30 and the connection region 34 of the connector 14. When access is required to the connector 14, for example, to make a connection thereto, the cover 40 is withdrawn so that the bore 36 and the waisted region 38 can be accessed through the T-shaped slot 50 in the housing 12. However, whilst it is easy to insert the stripped end of a wire through the slot 50 into the bore 36, or to engage a spade terminal around the waisted region 38 by way of the base of the T-slot 50, the T-slot 50 does not allow access to the connector 14 by a finger. As, in use, the connector 14 may be connected by way of its solder terminal 21 or 22 to an electrical supply, this denial of access to a finger is important.
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There are circumstances in which more than one insulated terminal is required and Figures 4 and 5 show individual terminals 10 as described above arranged to provide multiple terminals having two or four individual terminals 10. In this respect, and as will be apparent, a single base moulding 16 of appropriate size and shape is provided to receive the required number of individual terminals 10. These terminals 10 are identical to those described and illustrated with reference to Figures 1 to 3.
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Where a number of individual terminals 10 are mounted on a single base moulding 16 as shown in Figures 4 and 5 it is important to ensure that the T-slot 50 of each individual terminal 10 remains accessible. This is particularly important, as illustrated in Figure 6, where access is required for a spade adaptor indicated at 70. To facilitate the mounting of each terminal 10 on the base moulding 16 in the correct orientation, keyed cooperating means are provided on the housing 12 and on the base moulding 16. In this respect, the base moulding preferably has the necessary keyways and the base of the housing 12 carries the necessary keys.
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In the embodiment illustrated, the cylindrical extension 24 of each hollow housing 12 serves to define the key, and the widened portion of the bore 26 in the base moulding 16 serves to act as a keyway groove of the keyed cooperating means. For example, a flat (not visible) may be provided at one part of the cylindrical extension 24 of each hollow housing 12 and arranged to cooperate with a corresponding flat (not visible) in the widened part of the bore 26 of the base moulding 16.
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Figures 7 and 8 show alternative embodiments of multiple terminals having two or four individual terminals 10. In this respect, and as previously, a single base moulding 116 of appropriate size and shape is provided to receive the required number of individual terminals 10. However, in the embodiments of Figures 7 and 8 the base moulding 116 is provided additionally to the base moulding 16 of each individual terminal.
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Each individual terminal 10 still retains the cylindrical extension 24 of its hollow housing 12 and this is received within a widened bore portion providing a keyway groove in the base moulding 116. The individual base mouldings 16 of the terminals 10 act as retaining pieces for retaining each individual terminal 10 on the base moulding 116. In this respect, the base moulding 116 may be located on top of the facia of the equipment to be provided with the insulated terminals.
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In the embodiments illustrated, the cover 40 is substantially cylindrical in shape whilst the hollow housing 12 is substantially conical. However, it will be appreciated that any shapes may be chosen for these elements as is required. Other variations in and modifications to the terminals as described and illustrated may be made within the scope of this application.
