GB2228631A

GB2228631A - Plug adaptor for electrical branching

Info

Publication number: GB2228631A
Application number: GB8904452A
Authority: GB
Inventors: Robert William Taylor; John Yair
Original assignee: Cliff Electronic Components Ltd
Current assignee: Cliff Electronic Components Ltd
Priority date: 1989-02-27
Filing date: 1989-02-27
Publication date: 1990-08-29
Anticipated expiration: 2009-02-27
Also published as: GB8904452D0; GB2228631B

Abstract

An electrical plug comprises a housing (1) having at least two plastics parts (3, 5). The first (3) of these parts receives the plug electrode spigot (7) and the second (5) of these parts is insertable into the said first part (3). The parts (3, 5) are so arranged as to retain therebetween a cable (23) for connection to the electrode (7) in the plug and the second part (5) and rear end (29) of the spigot (7) form a socket (9) for receiving the electrode spigot of a second, similar plug therein enabling similar plugs to be electrically coupled in tandem. The spigot (7) includes an insulating tip (33) snap-fitted in place and is shielded optionally by a skirt (17). The second part (5) retains the electrode (7, 29) in position. A plastics socket enclosing a conducting electrode is provided for mating with the spigot (7) and includes an annular cavity to receive the skirt (17). The electrode is located at the open mouth by a socket lip and at the opposite end by a cap integrally hinged to the socket. The latter is screw-threaded for mounting with a nut in a panel aperture. <IMAGE>

Description

ELECTRICAL PLUG This invention relates to an electrical plug.

In many pieces of apparatus, particularly those which are used by children, it is necessary to have a foolproof plug arrangement which alleviates the likelihood of the user touching, at least with his fingers, any metal part of the plug, particularly that carrying an electrical current or signals, at least when the plug is inserted into a complimentary socket.

The present invention seeks to provide a plug of this type which is cheap to produce and easy to assemble.

According to the invention, a plug comprises a housing in having at least two plastics parts, a first of which receives the plug electrode spigot and the second of which is insert able into the said first part, is so arranged as to retain a cable for connection to the eiectrode in the plug and forms a socket for receiving the electrode spigot of a second similar plug therein enabling similar. plugs to be electrically coupled in tandem.

Preferably the second part is retained within the first part by a snap action and retains the cable by deforming the cable into an "S" shape.

The first part may be provided with a skirt which surrounds the electrode spigot, which latter may be recessed into the skirt and be provided with an insulated tip so that the skirt prevents touching of the main body of the electrode spigot and the insulated tip prevents contact by insertion of the fingers into the end of the skirt.

The invention also provides for the provision of a socket with which the plug is intended to cooperate.

The invention will now be described in greater detail, by way of example with reference to the drawings, in which: Figure 1 is a side view of one form of plug in accordance with the invention; Figure 2 is a sectional view of the plug of figure 1 taken on the line II - II of figure 1; Figure 3 is a sectional view of the plug of figure 1 taken on the line III - III of figure 2; Figure 4 is a sectional view of the plug of figures 1 to 3 inserted into a complimentary socket and, Figure 5 is a similar sectional view to that of figure 4, but showing two plugs connected in tandem.

Referring firstly to figures 1 to 3, there is shown a plug 1 which comprises first and second plastics parts 3 and 5 respectively and an electrode 7 comprising a metal tube 9 and a plastics tip portion 11.

The first part 3 forms the outer casing of the plug and to this end has a body 15 and a skirt 17. The base or inner end of the skirt 17 is apertured at 19 to receive the plug electrode 7. The interior of the body 15 is formed as a socket to receive the second part 5 and also has a cable guide surface 21 which, in combination with a cooperating surface on the second part 5, guides the cable 23 to one side to allow tandem connection of a plurality of plugs as will be explained in connection with figure 5 hereafter. The body 15 has a pair of lateral apertures 25 which cooperate in retaining the second part 5 as will be hereinafter described.

The electrode 7 comprises a rolled metal tube 9 having a first portion 27 forming the spigot part of the plug and a second portion 29 whose inside diameter is the same as the outside diameter of the first portion 27 and is adapted to receive the first portion of the electrode of a second plug when the plugs are connected in tandem.

The electrode is provided with a solder or clinch tag 31 extending laterally from the second portion 29 adjacent to the first portion 27. The plastics tip portion 11 comprises a rounded head 33 which sits on the free end of the first portion 27 of the tube 9 and a bifurcated stem 35 insert able into the first portion 27 and extending inwardly to the location of the solder tag 31.

At this point, one of the bifurcations has a laterally extending chamfered projection 37 which can be sprung inwards as a result of the bifurcated construction. This projection cooperates with an aperture 39 in the tube 9 and will spring into this aperture 39 with a snap action to secure the tip portion 11 firmly in place. The projection 37 extends out of the aperture 39 and engages behind a surface 41 on the body 15 to prevent movement of the electrode 7 out of the skirt 17 (i.e. to the right as seen in the drawings).

The second plastics part 5 has a plug portion 43 which is insert able into the socket formed by the body 15 and is so dimensioned as to engage the walls of the socket around the major part of its periphery and, about the remaining part of its periphery, forms, with the edge 45 of the socket, a channel for the cable 23. The plug portion 43 is formed with an annular recess 47 to receive the skirt of a further plug. The plug portion 43 is formed internally with an annular lip 49 against which the end of the tube 9, which is flared at this point, sits. The second part 5 also has a laterally extending end portion 53 which, when the second part 5 is inserted in the socket of the first part 3, will deform the cable 23 into an "S" shape and so secure it against pulling forces.The edge of the portion 53 extends inwards of the socket to provide a cable guide surface 55 which cooperates with the surface 21 of the body 15. Two chamfered projections 57 are formed on the exterior of the plug portion 43 and are resilient by virtue of the construction of the plug portion 43. These projections 57 cooperate in a snap connection with the apertures 25 in the body 15 of the first part 3.

Assembly of the plug will now be described: The cable 23 is first soldered or clinched to the tag 31 on the tube 9, and the plastics tip portion 11 is inserted into the end of the first portion 27. It is pushed home until the projection 37 snaps into the aperture 39. Next the tube is inserted into the part 3 from the body side thereof and pushed in until the projection 37 of the tip portion engages behind the surface 41, thus locating the electrode 7 in a first direction. Lastly, the second part 5 is pushed into the first part 3 until the projections 57 on the second part 5 snap into the apertures 25 in the body 15 of the first part 3. In this last action, the laterally extending end portion 53 of the second part 5 engages the cable 23 and deforms it into an "S" shape and thus retains it securely against pulling forces.At the same time, the cable 23 is guided to one side so as to enable connection with a second plug. Also the annular lip 49 will engage behind the flared end of the tube 9 and thus locate the electrode 7 in a second direction.

Figure 4 shows a socket 61 with which the plug 1 is intended to cooperate. It comprises a plastics body 63 having a head 65 and a threaded stem which is intended to receive a nut. By this means, the socket can be panel mounted with the panel sandwiched between the head 65 and the nut (not shown). The socket is provided with a main bore 67 intended, as shown, to receive the electrode 7 of the plug 1 and surrounding the bore 67 is an annular recess 69 intended to receive the skirt 17.

Contact is provide within the bore 67 by means of a metallic tube 71 having an internal diameter the same as the external diameter of the first portion 27 of the electrode 7. This tube 71 is retained in the bore 67 at one end by an annular lip 73 and at the other end by a hinged cap 75, hinged to the rest of the body 63 by a plastics hinge 77, and which closes off the inner end of the bore 67. A contact 79 extends past the hinged cap so as to be accessible for clinching or soldering (for example, to a printed circuit mounting).

Figure 5 shows the use of two identical plugs in tandem.

To this end the electrode 7 of the first plug 1A is received into the second portion 29 of the electrode 7 of the second plug 1B and the skirt 17 of the plug 1A is received into the annular recess in the second part 5 of the plug 1B.

It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention. For example, if not required, the skirt 17 may be omitted. While this has the disadvantage that the metallic part of the plug can be touched when out of the socket, nevertheless protection is provided once insertion has taken place.

From the above, it will be seen that the invention provides, in its specific embodiment, a plug construction in which no metal parts are touchable at any time (with skirt) and or only when connected up (without skirt) and which is cheap to manufacture and easy to assemble.

Claims

1. An electrical plug comprising a housing having at least two plastics parts, a first of which receives the plug electrode spigot and the second of which is insert able into the said first part, is so arranged as to retain a cable for connection to the electrode in the plug and forms a socket for receiving the electrode spigot of a second similar plug therein enabling similar. plugs to be electrically coupled in tandem.

2. A plug as claimed in claim 1, wherein the second part is retained within the first part by a snap action and retains the cable by deforming the cable into an "S" shape.

3. A plug as claimed in claim 1 or 2, wherein the spigot is formed from a metallic tube a first portion of which forms the spigot and the second portion of which has an inside diameter substantially the same as the outside diameter of the first portion to receive the spigot of a second similar plug.

4. A plug as claimed in claim 3, wherein the second part is formed with a bore in which the second portion of the metallic tube is received.

5. A plug as claimed in any one of ciaims 1 to 4, wherein the first part is provided with a skirt which surrounds the electrode spigot.

6. A plug as claimed in claim 5 wherein the spigot is recessed into the skirt.

7. A plug as claimed in claim 5 or 6, wherein the spigot is provided with an insulated tip.

8. An electrical plug substantially as described herein with reference to any of the figures of the drawings.

9. A socket for cooperation with a plug as claimed in any one of claims 1 to 8, wherein the socket comprises a plastics body, means for mounting the body in an aperture in a panel or the like, a 'bore therein for receiving the spigot of a plug therein and an electrode within the bore for making contact with the spigot of an inserted plug.

10. A socket as claimed in claim 9, wherein a metallic tube is provided in the bore to form the electrode.

11. A socket as claimed in claim 9 or 10, wherein the socket is provided with a head at the end of the body adjacent the mouth of the bore and is screw-threaded longitudinally adjacent thereto for receiving a nut such that the socket can be placed in an aperture in a panel and secured therein by sandwiching the panel between the head of the socket and the nut.

12 A socket for an electrical plug as claimed in any one of claims 1 to 8, the socket being substantially as described herein with reference to figure 4 of the drawings.