IE57262B1

IE57262B1 - Electric plug

Info

Publication number: IE57262B1
Application number: IE759/86A
Authority: IE
Original assignee: Ever Winner Electric Works Ltd
Priority date: 1986-03-18
Filing date: 1986-03-24
Publication date: 1992-06-17
Also published as: GB2190800A; IE860759L; GB8606621D0; GB2190800B; HK37791A

Abstract

An electrical plug comprises: a body (12) which, with the cover 156 removed, provides access for cable connection to respective live (40) and neutral (32) cable terminals on the body, live terminal (40) being located on the neutral pin side of the plug above the level of the live (16) and neutral pins; a cartridge fuse (not shown) extending within the plug at a level above the live and neutral pins, with one end of the fuse being connected, via a manually operable switch (74, 78, 90) to the live terminal (40), the switch (74, 78, 90) being located on the live pin (16) side generally at the same level as the fuse. The fuse is accessible from the pin-side of the body. The cover incorporates a neon indicator lamp (170) and two spring contacts (not shown) connected to the neon lamp. When the cover is located on the main body, the spring contacts abut metallic contacts connected respectively to the neutral pin and the switched side of the live supply.

Description

This invention relates to electrical plugs, and specifically, but not exclusively to such plugs of the 13 amp variety, i.e., having three flat or round pins for insertion in corresponding sockets of an electrical outlet in the United Kingdom or other countries utilising the same system.

The invention has, as its principal object, the provision of a novel and extremely compact switched and fused plug.

According to the present invention an electrical plug comprises a main body from a rear face of which extends a live and neutral pin, for insertion in corresponding sockets, the plug incorporating within it a manually operable switch which is positioned between the live pin and a live cable terminal, with the interposition of a removable fuse, to , which access is obtained solely from the rear face of the plug, and the switch including a switch actuator which is mounted within a removable fc, switch housing located on the main body of the plug, beneath a cover thereof. The switch may incorporate a stationary contact secured to the live pin, and a moving contact element carrying a moving contact for cooperation with the stationary contact, the moving contact element being located in position which is generally in line laterally with, but at a higher level than the live pin, and, in this case, the moving contact element may comprise a lever arm mounted to pivot on a fulcrum, the fulcrum being electrically connected, via the fuse to the live - 3 cable terminal, and the fulcrum being electrically connected to the stationary contact by the moving contact element when the moving contact element is in a closed position, to connect the live terminal, via the moving contact element and the fulcrum to the live pin.

The fulcrum may be formed integrally with a metallic element extending within the plug to a spring socket for receiving one end of a cartridge fuse and a second spring socket may be included for the other end of the cartridge fuse, the second spring socket being connected to the live terminal, and the two spring sockets being connected to the live terminal, and the two spring sockets being spaced apart horizontally within the plug.

The switch actuator may include a manually operable member which projects through an aperture in the front face of the cover. The switch housing may incorporate an overcentre rocker mechanism for actuating the switch.

The invention may be carried into practice in various ways but one specific embodiment will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an exploded perspective view of a 13 amp switched and fused plug according to the present invention; Figure 2 is a sectional side elevation of the plug on the line II-II of Figure 5, with cover and body separated but with the switch assembled and shown in its closed position; Figure 3 is a view of the body, which is similar to Figure 2, but which shows the switch in its open position; Figure 4 comprises, in Figure 4A, and Figure 4B respectively, a front elevation and a side elevation of the contact element of the switch; Figure 5 is a sectional plan on the line V-V of Figure 2; - 4 Figure 6 is a front elevation of the switch housing; Figure 7 is a sectional side elevation of the switch housing on the line VII-VII of Figure 6; Figure 8 is a front elevation of the main body of the plug, with the switch and switch housing removed i.e., generally as viewed in the direction of the arrow A in Figure 1; arid Figure 9 is a rear elevation of the interior of the cover of the plug, as viewed generally in a direction of the arrow B in Figure 1.

The embodiment shown in the drawings represents an example of the invention as applied to a 13 amp plug which, as will be described, incorporates a fuse to which access can only be achieved when the plug is removed from its socket, and a switch on the front of the plug by which an appliance connected to the plug top can be switched on or off.

In general, the plug is manufactured from mouldings of plastics material except for those parts which are utilised for the transmission of current, in which case they are made of brass Or similar alloys. There are also a few metallic assembly screws.

Referring firstly to Figure 1, this shows the main parts of the plug.

These include a main plastics body 10 from the rear face 12 of which project an earth pin 14, a live pin 16, and a neutral pin 18, which is shown in Figure 5. These pins are of conventional flat shape and disposition in order to be receivable in standard 13 amp sockets for example in the United Kingdom and other countries having the same system. Alternatively, the pins may be round.

The lower part of the main body includes an open, downwardly facing, recess 20 though which a three core cable can pass in conventional manner to be connected to the internal terminals, to be described, of the plug top. The recess has in it a strain relief bar 22, beneath which the cable extends, and by which it is gripped to the remainder of the plug by means of a pair of screws 24, shown in Figures 2 and 3, and which are accessible from the rear face 12 of the plug. The three - 5 cores of the cable, when cut to appropriate length, have their bared ends connected to appropriate terminals. Figures 1 and 8 illustrate the earth terminal 26 which has a clamping screw 28 for the earth core, the latter being inserted into an aperture, not shown, in the front end of the earth pin 14 on the left hand side in Figure 1 and 8. The neutral core of the cable is connected to a neutral terminal 32 having a clamping screw 34 for securing the bared end of the neutral core in a vertical hole passing through the front end of the neutral pin 18. In practice, connection of the neutral core to the neutral terminal 32 is best carried out by withdrawal of the neutral pin 18 forwardly of the main body in order to gain ready access to the vertical hole for the cable core.

Referring to Figure 1, the bared end of the live core of the cable is inserted into an aperture 36 which extends horizontally across the front end 38 of a live terminal 40 having a vertically extending clamping screw 42. The live terminal 40 is also shown in Figure 5 which is a section or plan of the plug. The terminal 40, to the rear of the screw 42, has a reduced portion 44 which extends through a transverse bulkhead 46 of the plug and which has riveted to it a U-shaped spring fuse terminal or socket 50 for receiving one end of a cartridge fuse 52. The fuse is carried by a plastics sleeve 51 which is integral with a plastics fuse-cover 53 which snaps in position to lie in the plane of the rear face 12 of the main body. The other end of the fuse 52 is received in a similar terminal or socket 54 which is secured by a rivet 56 extending through an aperture 57 in the bulkhead 46, and securing the terminal or socket 54 of the fuse to one end 58 of an S-shaped metallic plate 55 extending generally transversely of the plug behind the fuse. The plate 55 has an intermediate portion 60 extending rearwardly from the. right-hand edge of the end 58 of the plate, and merging into a further end portion 62, which is located against the vertical rear face 66 of a forwardly facing recess 68 in the plug and which generally receives other parts of the switch of the plug, as will be described.

Thus referring to Figures 2, 3, 5 and 8 it will be seen that the upper edge of the transverse end portion 62 of the S-shaped metallic plate has a narrow strip 70 extending forwardly and upwardly at an angle of approximately 45°. As is best shown in Figure 8, the centre portion of this strip is cut away to form a small recess 72 leaving a pair of fulcrum lugs 74, one at each end.

Cooperating with the fulcrum lugs 74 is a movable contact element generally indicated at 78 in Figures 1 to 3, and the form of which is shown in detail in Figures 4A and 4B. The contact strip is produced as a metallic stamping from brass, and in a generally central region, has a pair of forwardly punched portions 80 to leave a rearwardly facing notch 82 on each side, to receive the fulcrum lugs 74.

The upper edge 84 of the contact element 78 is straight but immediately below this edge the contact element has a transverse forward projection 86 for a purpose to be described. The lower end of the contact element 78 is generally semi-circular in form, and carries a moving contact 88 of the switch. Intermediate the location of the forwardly punched portions 80, and the moving contact 88, the contact element 78 has, on each side, a further forwardly facing lug 90 of which the left-hand lug, as viewed in Figure 1 acts with the adjacent face of the forwardly extending portion of the S-shaped plate, partially to locate the contact element 78 and prevent it tilting. The right-hand lug 80 in Figure 1 cooperates with a wall of the recess 68 (which for visibility has been cut away in Figure 1) for a similar purpose. The manner in which the contact element 78 is moved from its closed or on position of Figures 1 and 2, to the open or off position of Figure 3 will be discussed later.

In the on position the moving contact 88 engages a stationary contact 94, best seen in Figures 2 and 3, which is carried on the upper rear face of a stationary switch contact element 96 which, in turn, is riveted, as shown in Figures 2 and 3, to the front end of the live pin 16 of the plug. Thus, in the closed or “on position of Figures 1 and 2 of the switch, continuity from the live pin 16 is achieved via the stationary contact element 96, the stationary switch contact 94, the moving contact 88, the contact element 78, the fulcrum lugs 74, the S-shaped plate, the right-hand fuse socket 54 (see Figure 5), the fuse 52, the left-hand fuse socket 50, and the live terminal 40 to which the live cable core is connected. When the switch is in the open position - 7 of Figure 3, and the contacts 88 and 94 are separated, all internal parts of the plug top, which would otherwise be live, from the moving contact 88 through to the live terminal 40 are disconnected from the live supply.

Those parts of the switch which cause the movement of the contact t element between the positions of Figures 2 and 3 will now be described. Thus, referring to Figures 1 to 3 and Figures 6 and 7 in 4 particular, the switch incorporates a manually operated toggle 100 which comprises a small rectangular cup-like moulding having a front face 102, by which it is manipulated by hand, when the switch is operated, an upper inclined face 104, a lower inclined face 106, (see Figures 2 and 3) and a pair of side walls 108 and 110.

Extending rearwardly from the front wall 102, within the moulding, is a hollow hub 112, within which is received the front end of a plastics actuator pin 114 having a reduced front end 116 for locating a small compression spring 118. The rear end 120 of the actuator tapers to a point which contacts the generally central area of the contact element 78 in the region of the forwardly punched portions 80, which receive the fulcrum lugs 74. In the on position of Figure 2, the tapered rear end 120 of the actuator 114 lies adjacent the transverse forward projection 86, the latter limiting upward movement of the rear end 120 of the actuator, with respect to the contact element 78. It will be seen from Figure 2 that, in this position, the line of action of the spring 118 on the actuator 114 positions the tip of the actuator above the fulcrum lugs 74, to hold the switch firmly in the on condition of Figure 2.

Actuation, for example by a thumb, to tilt the toggle 100 to the position of Figure 3, causes the line of action of the spring 118 and actuator 114 to pass below the line of the fulcrum lugs 74, so causing the contact element 78 to snap to an “open position as shown in Figure 3.

For this purpose the toggle 100 has, on each side, as shown in Figure 1, an integral generally pear shaped trunnion 122. These trunnions cooperate with generally triangular recesses 124 which are formed on - 8 the inside surfaces of side walls 126 of a switch housing generally indicated at 128, and which is formed of plastics moulding. The moulding is generally rectangular in form to provide a top wall 130, and a bottom 132, and each Side wall 126 on its external surface is built up by a rectangular block 134, behind which the triangular recesses 124 are formed. The moulding also includes a pair of apertured lugs 136 and 138, at bottom right and top left corners respectively, by which the switch housing is secured by short metallic self-tapping screws extending into bores 140 in the main body 10.

As shown in Figure 6 the switch housing 128 has, on its left-hand side, an integral L-shaped projection 142 of which a vertical portion 144 lies in front of the rivet 56, for which purpose the portion 144 has a small circular recess 146 on its underside which fits around the head of the rivet 56. This serves both to locate the switch housing with respect to the remainder of the assembly, and also, by virtue of a horizontal portion 148 of the L-shaped projection 142, which underlies the front end of the earth pin 14, provides an insulation between the live side of the plug when switched on, and the earth pin 14. The front surface of the vertical portion 144 also serves to guide the live and earth cores of the cable without any risk of any bare portion thereof engaging the riveted part 56 of the assembly.

The switch housing has a rectangular opening 150 in its front face, through which the toggle 100 can partially project, as shown in Figure 7.

Referring now to Figures 1, 2 and 5, the form of the cover 156 of the plug, and its internal parts, will now be described.

As indicated, the plug is a hollow moulding of plastics material having a front face 158 and a surrounding side wall or skirt 160, which, as shown in Figure 2, has a small opening 162 for the entry of the cable. The front face 158 has a rectangular opening 164 which, on assembly, is aligned with the switch housing to permit access to the toggle 100 of the switch from the front of the assembled plug.

As shown in Figures 2 and 9, mounted within the cover 156 is a neon - 9 lamp 168 which lies behind a coloured insert 170 in the front face 158 of the cover 156. One lead 172 from the neon lamp 168 extends to a metallic compression spring 174 which is mounted in a hollow post 176 within the cover 156, the spring 174 protruding slightly from the rear end of the post 176 as shown in Figure 2, and being dimensioned to engage the front end or head of the neutral terminal screw 34. A second lead 180 extends from the neon lamp 168, via a resistor 182, to a spring contact 184 which is arranged, on assembly of the cover, to engage the face 38 of the live terminal 40. Thus, when the switch is in the on position, and the live terminal 40 is connected to supply, a supply to the neon lamp is assured to provide an illumination at the front of the plug. The neon lamp and its connections to the spring and the spring contact are protected by an insulated insert 186, shown in Figure 2.

In its interior, as shown in Figure 9, the cover 156, has a central locating post 188 and a pair of screw-receiving posts 190 and 192 for receiving securing screws which pass, from the rear face 12 of the main body, through bores 194 and 196 respectively in the main body.

In the specification and claims, the terms horizontal and vertical are referred to the plug orientation which is shown in figure 8. The lateral direction corresponds to a line drawn between the live and neutral pins of the plug.

Claims

CLAIMS - 10 1. An electrical plug comprising a main body from a rear face of which extends a live and a neutral pin, for insertion in corresponding sockets, the plug incorporating within it a manually operable switch which is positioned between the live pin and a live cable terminal, ί» 10 with the interposition of a removable fuse, to which access is obtained solely from the rear face of the plug, and the switch including a switch actuator which is mounted within a removable switch housing located on the main body of the plug, beneath a cover thereof. 15
2. A plug as claimed in Claim 1 in which the switch incorporates a stationary contact secured to the live pin, and a moving contact element carrying a moving contact for cooperation with the stationary contact, the moving contact element being located in a position which is generally in line laterally with, but at a higher level than the 20 live pin.
3. A plug as claimed in Claim 2, in which the moving contact element comprises a lever arm mounted to pivot on a fulcrum, the fulcrum being electrically connected, via the fuse, to the live cable terminal, and 25 the fulcrum being electrically connected to the stationary contact by the moving contact element when the moving contact element is in a closed position, to connect the live terminal, via the moving contact element and the fulcrum, to the live pin. 30
4. A plug as claimed in Claim 3, in which the fulcrum is formed integrally with a metallic element extending within the plug to a spring socket for receiving one end of a cartridge fuse.
5. A plug as claimed in Claim 4, including a second spring socket 35 for the other end of the cartridge fuse, the second spring socket being connected to the live terminal, and the two spring sockets being spaced apart horizontally within the plug. - 11 6. A plug as claimed in any one of the preceding claims in which the switch housing incorporates an over-centre rocker mechanism for actuating the switch. 57. A plug as claimed in any one of the preceding claims, in which the switch actuator includes a manually operable member which projects » through an aperture in the front face of the cover. 11 8. A plug as claimed in Claim 7, in which the manually operable 10 member comprises a toggle, supported within the switch housing by a pair of trunnions.
6. 9. A plug as claimed in Claim 8, in which the toggle and the switch housing are plastics mouldings. 15
7. 10. A plug as claimed in any one of the preceding claims when dependant upon Claim 2 in which the switch actuator includes a spring loaded actuating member arranged to press against the moving contact element to hold the switch in the open or the closed position, the 20 actuating member being arranged for sliding motion with respect to the moving contact element for actuation of the switch.
8. 11. A plug as claimed in any one of the preceding claims in which the switch housing includes an integral portion providing electrical 25 insulation between the earth pin and the live side of the plug.
9. 12. A plug as claimed in any one of the preceding claims in which the fuse extends horizontally within the plug. 30
10. 13. A plug as claimed in any one of the preceding claims including a neon indicator lamp which, when lit, is visible from the front face of 2 the cover.
11. 14. A plug as claimed in Claim 13 in which the sides of the neon lamp 35 are connected respectively to the neutral pin and to the switched side of the live supply via first and second spring contacts. - 12 15. A plug substantially as specifically herein described, with reference to and as shown in the drawings.