GB1599318A - Electrical plug - Google Patents

Description

(54) ELECTRICAL PLUG (71) We, LUCAS INDUSTRIES LI MITED, a British Company of Great King Street, Birmingham, B19 2XF, do hereby declare that the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an electrical plug, particularly but not exclusively, for use in domestic electrical wiring, the plug being of the type comprising an electrically insulating body supporting a pair of male terminal pins and a fuse arrangement whereby in use an electrical connection is made to one of the pins. said terminal pins extending parallel to one another from one face of the body for insertion into female terminals of a mating electrical socket.

In a conventional electrical plug of the kind specified one of the pins is designated as the live pin and the other is designated as the neutral pin. The fuse arrangement is provided internally of the plug body which is generally of two-part construction. The fuse arrangement includes a fuse and a pair of fuse clips. one of the fuse clips being electrically connected to the live terminal pin and the other of the fuse clips being connected to an internal terminal for attachment to the live lead of the cable to which the plug is applied. The parts of the body are normally secured together by one or more screws and thus it is necessary to dissemble the body when the fuse is to be replaced. This of course is a disadvantage of the conventional plug since in general fuses are replaced by the householder and thus it is necessary for the householder to obtain the necessary tool to remove the screw or screws and to exhibit the necessary dexterity in dissembling and subsequently reassembling the body. It is of course known that many householders will approach such a task with trepidation.

In a further known form of electrical plug the electrical connections between the leads of the cable and the terminal pins of the plug are made prior to moulding of the body and the body is then moulded around the plug and the lead. In such an arrangement of course an internal fuse would be totally impractical since the body is not dissemblable to permit replacement of the fuse. With plugs moulded onto the lead it is usual to provide the replaceable fuse at the appliance itself and thus the householder is called upon to actually dissemble parts of the appliance to replace the fuse.

It is an object of the present invention to provide an electrical plug with a replaceable fuse wherein the foregoing problems are minimised.

According to the invention in a plug of the kind specified there is formed a recess in said one face of the insulating body for receiving a fuse, the plug including a pair of fuse connecting clips which are secured within said recess, one of the pair of clips being electrically connected within the plug to one of said terminal pins and the other of said clips being electrically connected in use to one of the leads of the cable to which the plug is applied, and a fuse carrier comprising an anchor portion secured in said recess by the means securing one of said clips in the recess, and a movable portion connected to said anchor portion, said movable portion being arranged to carry a fuse and to be movable relative to the body and the anchor portion to engage the fuse with and disengage the fuse from said clips.

Preferably, in the position occupied by the movable portion when a fuse carried thereby is engaged in said clips, the movable portion closes said recess.

Desirably said anchor portion and said movable portion of said fuse carrier are interconnected by an integral hinge.

Conveniently said fuse connector clips are secured by respective rivets to respective terminals anchored in the body, said anchor portion of said fuse carrier being trapped between the body and one of said clips and so being secured in the recess by the rivet of said one clip.

Desirably, a first lead of an electrical cable is electrically connected to said terminal within the body, and is thus connected by way of a fuse engaged in said clips to said one terminal pin, a second lead of said cable is electrically connected to said second terminal pin, and the electrically insulating body is moulded around those portions of the leads connected to the other terminal pin and said terminal within the body.

The accompanying drawing is a diagrammatic partly cross-sectional representation of part of an electrical plug in accordance with one example of the present invention.

Referring to the drawings, the electrical plug includes a moulded synthetic resin body 11 which is moulded around the end region of a three core cable. One face of the body 11 is formed with a rectangular recess 13, and three brass terminal pins of the plug extend from the face 12 parallel to one another. In accordance with the electrical wiring convention currently in force the three pins are of rectangular cross-section and are arranged in a triangular pattern.

One of the pins, designated the earth pin, is of larger dimensions than the other two pins, designated respectively the live pin and the neutral pin. The three leads of the cable around which the body 11 is moulded are respectively a live lead a neutral lead and an earth lead. Prior to moulding the body 11 the earth lead is electrically connected to the earth terminal, the neutral lead is electrically connected to the neutral terminal pin, and the live lead is electrically connected to a terminal member 14 which includes a deformable shank 14a. The live pin is electrically connected to a conductive bridging strip which terminates in a deformable shank similar to the shank 14. The end portion of the lead carrying the terminal pins and the terminal block 14 are positioned together with the live pin and its associated electrical connector in a mould defining the exterior shape of the body 11.

The shank 14a of the member 14 and the similar shank of the member associated with the live pin project into a core region of the mould shaped to define the rectangular recess 13. Thereafter the electrically insulating body 12 is moulded in the mould and is thus moulded around the end region of the cable, the individual leads of the cable, and the ends of the three terminal pins.

Upon removal of the moulded plug from the mould it will be seen that the shank 14a and the equivalent shank of the member associated with the live pin project through the base of the recess 13 and into the recess 13. The deformable shank 14a and the equivalent shank of the member associated with the live terminal pin serve to secure fuse clips within the recess. The fuse clips 15 are identical and each comprise a U-shaped strip of conductive spring material, the parallel limbs of the two clips being arranged to receive therebetween the terminal caps of a cartridge fuse 16. The shank 14a and the equivalent shank of the member associated with the live terminal pin pass through apertures in the base part of each of the clips and are deformed to retain the clips 15 in the recess, and at the same time to make the electrical connections between the clips and the live terminal pin on the one hand and the terminal member 14 on the other hand.

There is further provided a fuse carrier 17 which is moulded in synthetic resin material.

The fuse carrier 17 includes an anchor portion 18, a movable, cover portion 19 and an integral hinge 21 uniting the portion 18, 19. The anchor portion 18 is generally L-shaped with the hinge 21 at one end of the two limbs and an aperture 22 in its other limb. The apertured limb of the anchor portion 18 is disposed in engagement with the base of the recess 13 prior to engagement of the clip 15 with the shank 14a of the member 14. The shank 14a passes through the aperture 22 of the limb and through an aperture in the base portion of the cli 15 so that after deformation of the free end of the shank 14a the anchor portion 18 is secured within the recess by being trapped between the clip 15 and the base of the recess, the anchor portion thus being held by the same means which hold the clip 15 in position. In order that the two clips 15 shall be disposed at the same level within the recess 13 a spacer member 23 of insulating material is disposed between the other clip 15 and the base of the recess prior to deformation of the shank equivalent to the shank 14a.

The limb of the anchor portion 18 which carries the hinge 21 at its upper free end extends along an end wall of the recess 13 from the base towards the open end of the recess. The hinge 21 is at the open end of the recess 13 and the portion 19. which is shaped in accordance with the open face of the recess 13, can be moved by virtue of the hinge 21 from a position wherein it closes the open face of the recess 13 to a position wherein access can be gained to the interior of the recess 13. The portion 19 is formed on its face presented to the interior of the recess 13 with an integral strap 24. The strap 24 defines a passage 25 having its axis aligned with the length of the cover portion 19 and through which a cartridge fuse 16 can be introduced. In the closed position of the portion 19 the strap 24 extends downardly towards the base of the recess between the clips 15 and the terminal caps of the fuse 16 project on either side from the passage 25 for engagement with the clips 15. As with the conventional clips 15 the caps of the fuse are gripped by the clips 15 and thus the movable cover portion 19 is held in its closed position by the clips 15 gripping the fuse 16. A small clearance is left between the free end of the portion 19 and the wall of the recess 13 to permit insertion of a small blade, or a finger nail or the like beneath the portion 19 to facilitate lifting of the portion 19 about the hinge 21 to extract the fuse 16 from the clips 15. Thereafter the fuse 16 can be moved longitudinally from the confines of the strap 24 to permit replacement.

The portion 19 is formed with an aperture 26 in the region of the strap 24 whereby the central region of the fuse 16 is visible from the face 12 so that the rating of the fuse 16 may be ascertained without removal of the fuse from the clips 15.

It will be understood that since the recess 13 is in the face 12 of the body 11 from which the terminal pins project then in order to gain access to the movable cover member 19, and ultimately to the fuse 16 it is necessary that the plug is disengaged from its mating socket by withdrawing the pins from the mating female terminals of the socket. It follows therefore that since the socket is the supply point then access cannot be obtained to exposed live parts of the assembly. The plug must be removed thereby rendering it electrically dead before access can be gained to the fuse and the clips 15.

It will be understood that the manufacturing sequence described above is by way of example only. For example in a more practical arrangement it is probable that the terminal pins, the terminal member 14, the connecting member associated with the live pin, the carrier 17 and the clips 15 will be assembled together with their electrical connections to the lead on a moulded synthetic resin sub-body, the sub-body then being introduced into a moulding therearound of the main body of the plug. In this way of course the necessity of performing a rivetting operation internally of the clips 15 and internally of the recess 13 will be avoided.

The clips are of course open at each end and the rivetting operation can be performed considerably more conveniently from the open ends of the clips when the clips are not within the recess 13.

It will further be appreciated that while the constructions described above are constructions wherein the body is moulded around the lead it is clear that a similar arrangement can be provided wherein the body is in two detachable parts to facilitate applying the plug to a cable of the householders choice. In such an arrangement the recess 13 will be provided in the face of the body part from which the terminal pins project and the other body part will be removable to provide access to the interior ends of the neutral and earth terminal pins and to the terminal member 14 for connection thereto of the respective leads of the cable. However, access to the fuse will be achieved by way of the movable portion 19 of the carrier 17 without the need for dissembly of the body parts.

WHAT WE CLAIM IS: 1. An electrical plug of the kind specified wherein a recess is formed in said one face of the insulating body for receiving a fuse, the plug including a pair of fuse connecting clips which are secured within said recess, one of the pair of clips being electrically connected within the plug to one of said terminal pins and the other of said clips being electrically connected in use to one of the leads of the cable to which the plug is applied, and a fuse carrier comprising an anchor portion secured in said recess by the means securing one of said clips in the recess, and a movable portion connected to said anchor portion, said movable portion being arranged to carry a fuse and to be movable relative to the body and the anchor portion to engage the fuse with and disengage the fuse from said clips.

2. A plug as claimed in claim 1 wherein in the position occupied by the movable portion when a fuse carried thereby is engaged in said clips, the movable portion closes said recess.

3. A plug as claimed in claim 1 or claim 2 wherein said anchor portion and said movable portion of said fuse carrier are interconnected by an integral hinge.

4. A plug as claimed in any one of claims 1 to 3 wherein said fuse connector clips are secured by respective rivets to respective terminals anchored in the body, said anchor portion of said fuse carrier being trapped between the body and one of said clips and so being secured in the recess by the rivet of said one clip.

5. A plug as claimed in any one of claims 1 to 4 wherein a first lead of an electrical cable is electrically connected to said terminal within the body, and is thus connected by way of a fuse engaged in said clips to said one terminal pin, a second lead of said cable is electrically connected to said second terminal pin, and the electrically insulating body is moulded around those portions of the leads connected to the other terminal pin and said terminal within the body.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. towards the base of the recess between the clips 15 and the terminal caps of the fuse 16 project on either side from the passage 25 for engagement with the clips 15. As with the conventional clips 15 the caps of the fuse are gripped by the clips 15 and thus the movable cover portion 19 is held in its closed position by the clips 15 gripping the fuse 16. A small clearance is left between the free end of the portion 19 and the wall of the recess 13 to permit insertion of a small blade, or a finger nail or the like beneath the portion 19 to facilitate lifting of the portion 19 about the hinge 21 to extract the fuse 16 from the clips 15. Thereafter the fuse 16 can be moved longitudinally from the confines of the strap 24 to permit replacement. The portion 19 is formed with an aperture 26 in the region of the strap 24 whereby the central region of the fuse 16 is visible from the face 12 so that the rating of the fuse 16 may be ascertained without removal of the fuse from the clips 15. It will be understood that since the recess 13 is in the face 12 of the body 11 from which the terminal pins project then in order to gain access to the movable cover member 19, and ultimately to the fuse 16 it is necessary that the plug is disengaged from its mating socket by withdrawing the pins from the mating female terminals of the socket. It follows therefore that since the socket is the supply point then access cannot be obtained to exposed live parts of the assembly. The plug must be removed thereby rendering it electrically dead before access can be gained to the fuse and the clips 15. It will be understood that the manufacturing sequence described above is by way of example only. For example in a more practical arrangement it is probable that the terminal pins, the terminal member 14, the connecting member associated with the live pin, the carrier 17 and the clips 15 will be assembled together with their electrical connections to the lead on a moulded synthetic resin sub-body, the sub-body then being introduced into a moulding therearound of the main body of the plug. In this way of course the necessity of performing a rivetting operation internally of the clips 15 and internally of the recess 13 will be avoided. The clips are of course open at each end and the rivetting operation can be performed considerably more conveniently from the open ends of the clips when the clips are not within the recess 13. It will further be appreciated that while the constructions described above are constructions wherein the body is moulded around the lead it is clear that a similar arrangement can be provided wherein the body is in two detachable parts to facilitate applying the plug to a cable of the householders choice. In such an arrangement the recess 13 will be provided in the face of the body part from which the terminal pins project and the other body part will be removable to provide access to the interior ends of the neutral and earth terminal pins and to the terminal member 14 for connection thereto of the respective leads of the cable. However, access to the fuse will be achieved by way of the movable portion 19 of the carrier 17 without the need for dissembly of the body parts. WHAT WE CLAIM IS:

1. An electrical plug of the kind specified wherein a recess is formed in said one face of the insulating body for receiving a fuse, the plug including a pair of fuse connecting clips which are secured within said recess, one of the pair of clips being electrically connected within the plug to one of said terminal pins and the other of said clips being electrically connected in use to one of the leads of the cable to which the plug is applied, and a fuse carrier comprising an anchor portion secured in said recess by the means securing one of said clips in the recess, and a movable portion connected to said anchor portion, said movable portion being arranged to carry a fuse and to be movable relative to the body and the anchor portion to engage the fuse with and disengage the fuse from said clips.

2. A plug as claimed in claim 1 wherein in the position occupied by the movable portion when a fuse carried thereby is engaged in said clips, the movable portion closes said recess.

3. A plug as claimed in claim 1 or claim 2 wherein said anchor portion and said movable portion of said fuse carrier are interconnected by an integral hinge.

4. A plug as claimed in any one of claims 1 to 3 wherein said fuse connector clips are secured by respective rivets to respective terminals anchored in the body, said anchor portion of said fuse carrier being trapped between the body and one of said clips and so being secured in the recess by the rivet of said one clip.

5. A plug as claimed in any one of claims 1 to 4 wherein a first lead of an electrical cable is electrically connected to said terminal within the body, and is thus connected by way of a fuse engaged in said clips to said one terminal pin, a second lead of said cable is electrically connected to said second terminal pin, and the electrically insulating body is moulded around those portions of the leads connected to the other terminal pin and said terminal within the body.

6. An electrical plug substantially as

hereinbefore described with reference to the accompanying drawings.