GB1584619A - Electrical plug - Google Patents

Description

(54) ELECTRICAL PLUG (71) We, LUMEX (PROPRIETARY) LIMITED, a company registered according to the laws of the Republic of South Africa, of Cnr.

11th Road and 2nd Avenue, Kew, Johannesburg, Transvaal, Republic of South Africa, do hereby declare 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 which is used to connect an electrical appliance to an outlet socket.

One of the problems with plugs of this type known to the applicant is the time needed to effect the connections of electrical conductors to the plug. A fair proportion of this time is taken up by initially separating the plug into its two halves and then at a later stage reassembling the two halves.

It is an object of the present invention to provide an improved electrical plug.

According to the invention there is provided an electrical plug which comprises a base, terminal pins supported by the base, and a lid, the base having a first member which projects from the body of the base into the interior of the assembled plug, the lid having a second member opposing the first member and projecting from the body of the lid into the interior of the assembled plug, the first and second members having formations which are located in the interior of the assembled plug and which are interengageable releasably to secure the lid to the base, and the base having a hole formed in it so that suitable means may be inserted into the hole and operated to disengage the interengaged formations.

The terminal pins may be slidably supported by the base, the lid including formations which bear on the pins when the lid is secured to the base to prevent movement of the pins relatively to the base.

At least one terminal pin may have a screw at an oblique angle to the longitudinal axis of the pin for connecting an electrical conductor to the pin.

The base and the lid may be made from polycarbonate.

The invention is further described by way of examples with reference to the accompanying drawings in which: Figure 1 is a plan view of an electrical plug according to the invention, Figure 2 is a sectional elevation of the base with a fitted lid, along the line 2-2 of Figure 1, Figure 3 is a fragmentary elevation of the base with a fitted lid taken along the line 3-3 of Figure 1, and showing the manner in which a terminal pin is supported in the base, and Figures 4, 5, and 6 are similar to Figures 1, 2 and 3 respectively, but illustrating a plug accord ing to a second form of the invention.

Referring to Figures 1 to 3 a plug 10 consists of a base 12 supporting live, neutral and earth pins, 14, 16 and 18 respectively, and a lid 20. The various pins are slidably fitted into holes in the base. The earth pin 18 has an internally threaded hole which is also at right angles to the longitudinal axis, and which intersects a hole 22. A screw 24 is fitted to the threaded hole in each pin.

The base 12 has an inlet 26 through which electrical conductors pass to the various pins and flexible protrusions 28 are pivotally fixed on each side of the:inlet 26 to grasp the electrical conductors and prevent them from being pulled out of the plug. Upwardly projecting hinge members 30 are formed at each side of the inlet 26. A similar member 32 is formed more or less at the centre of the body of the base 12 and a hole 34 is formed in the base adjacent the member 32.

Hinge members 36 detachably engageable with the members 30 project from the lid 20.

In similar fashion a member 38 is formed on the lid opposite the member 32, each of the members being provided with hook-like formations so that they can be clipped together.

Formations 40 project from the lid and are so positioned that when the lid is placed on the base the formations 40 are forced against the upper ends of the pins and so prevent the pins from moving in the base. The base 12 and lid 20 are made from a suitable plastics material so that the various hinge members are resilient and deflect slightly and then return to their original positions when the base and lid are clipped together. A most desirable material is polycarbonate for it has good heat resisting properties and a high electrical resistivity.

Moreover it is a strong material with an inherent degree of resilience with the result that the members 32 and 38 particularly are robust and can be interengaged and disengaged a number of times without being unduly weakened.

The plug is supplied in the form illustrated in Figure 2. To connect the plug to electrical conductors, a screwdriver or similar instrument is inserted through the hole 34 in the base 12 to prise the members 32 and 38 apart. The lid is then lifted from the base to expose the pins.

The electrical conductors, once the insulation has been stripped from their free ends, are connected to the various terminals by means of the screws 24, the making of the connections being facilitated by the fact that the screws on the live and neutral pins are at an oblique angle to the longitudinal axes of the pins. The making of the connections is also simplified by the fact that the pins are slidably fitted to the base 12.

Once the connections have been made the conductors are forced between the protrusions 28, and the hinge members 30 and 36 on the base and the lid respectively are engaged with each other correctly to position the lid on the base. The lid is then pushed down on the base so that the members 32 and 38 clip to each other. The correct siting of the lid on the base is assisted by the formations 40 which seat on the free ends of the pins and wluich are surrounded at least partially by the rim of the base.

The plug 50 shown in Figures 4 to 6 is similar in many respects to the plug 10 shown in Figures 1 to 3, and therefore is not described in detail.

The plug 50 is also made from polycarbonate. Its lid 52 and base 54 have inwardly projecting members 56 and 58 respectively. These members have hook-like interengageable formations 60 at their ends.

As is apparent from Figure 5 these formations have abutting surfaces 62 which are inclined to the flat external surfaces of the lid and the base. Thus, a fair amount of force is needed to press the base and the lid together so that the formations 60 engage with each other. On the other hand, when the formations are prised apart by means of a screwdriver inserted through the hole 64 in the base 54, the base and the lid jump slightly apart as a result of the released tension.

The live and neutral pins 66 and 68 respectively have holes 70 formed radially in them. The pins are ensconced in formations 72 on the base so that the holes 70 face towards the front, or earth pin side, of the base.

Talus means that the conductors connected to the live and neutral pins diverge more from each other than what is the case with the conductors connected to the plug base of Figure 1; consequently the likelihood of these conductors inadvertently touching each other is decreased.

The plug base 54 is formed with inwardly projecting annular ribs 74 on the internal surface of each of the holes 76 which receive the various terminal pins. A complementary annular groove 78 is formed on the periphery of each pin - this is best seen in Figure 6.

Each pin is forced into a hole 76 by means of a suitable press, and once the groove 78 and the rib 74 engage with each other the pin is securely attached to the base.

This method of attaching the pins to the base is particularly attractive for it obviates the necessity of moulding the pins in situ to the base, or of using additional components to secure the pin to the base.

In other respects, as previously indicated, the plugs 10 and 50 are similar to each other.

Each plug dispenses with screws for securing the lid to the base, yet may be rapidly assembled or disassembled as desired.

WHAT WE CLAIM IS: 1. An electrical plug which comprises a base, terminal pins supported by the base, and a lid, the base having a first member which projects from the body of the base into the interior of the assembled plug, the lid having a second member opposing the first member and projecting from the body of the lid into the interior of the assembled plug, the first and second members having formations which are located in the interior of the assembled plug and which are interengageable releasably to secure the lid to the base, and the base having a hole formed in it so that suitable means may be inserted into the. hole and operated to disengage the interengaged formations.

2. An electrical plug according to claim 1 in which at least one of the first and second members is made from a suitable material so that its formation is resiliently deflectable from and subsequently engageable with the formation on the other member as the lid and the base are pressed together.

3. An electrical plug according to claim 1 or 2 in which at least one terminal pin has a screw at an oblique angle to the longitudinal axis of the pin for connecting an electrical conductor to the pin.

4. An electrical plug according to any one of claims 1 to 3 in which each pin has a groove formed in its periphery, the groove being engageable with a complementary rib on the base to secure the pin to the base.

5. An electrical plug according to claim 4 in which the groove in each pin is annular and extends round the periphery of the pin.

6. An electrical plug according to any one of claims 1 to 5 in which the base and the lid are made from polycarbonate.

7. An electrical plug according to any one of claims 1 to 6 in which the terminal pins are slidably supported by the base, the lid includ

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. properties and a high electrical resistivity. Moreover it is a strong material with an inherent degree of resilience with the result that the members 32 and 38 particularly are robust and can be interengaged and disengaged a number of times without being unduly weakened. The plug is supplied in the form illustrated in Figure 2. To connect the plug to electrical conductors, a screwdriver or similar instrument is inserted through the hole 34 in the base 12 to prise the members 32 and 38 apart. The lid is then lifted from the base to expose the pins. The electrical conductors, once the insulation has been stripped from their free ends, are connected to the various terminals by means of the screws 24, the making of the connections being facilitated by the fact that the screws on the live and neutral pins are at an oblique angle to the longitudinal axes of the pins. The making of the connections is also simplified by the fact that the pins are slidably fitted to the base 12. Once the connections have been made the conductors are forced between the protrusions 28, and the hinge members 30 and 36 on the base and the lid respectively are engaged with each other correctly to position the lid on the base. The lid is then pushed down on the base so that the members 32 and 38 clip to each other. The correct siting of the lid on the base is assisted by the formations 40 which seat on the free ends of the pins and wluich are surrounded at least partially by the rim of the base. The plug 50 shown in Figures 4 to 6 is similar in many respects to the plug 10 shown in Figures 1 to 3, and therefore is not described in detail. The plug 50 is also made from polycarbonate. Its lid 52 and base 54 have inwardly projecting members 56 and 58 respectively. These members have hook-like interengageable formations 60 at their ends. As is apparent from Figure 5 these formations have abutting surfaces 62 which are inclined to the flat external surfaces of the lid and the base. Thus, a fair amount of force is needed to press the base and the lid together so that the formations 60 engage with each other. On the other hand, when the formations are prised apart by means of a screwdriver inserted through the hole 64 in the base 54, the base and the lid jump slightly apart as a result of the released tension. The live and neutral pins 66 and 68 respectively have holes 70 formed radially in them. The pins are ensconced in formations 72 on the base so that the holes 70 face towards the front, or earth pin side, of the base. Talus means that the conductors connected to the live and neutral pins diverge more from each other than what is the case with the conductors connected to the plug base of Figure 1; consequently the likelihood of these conductors inadvertently touching each other is decreased. The plug base 54 is formed with inwardly projecting annular ribs 74 on the internal surface of each of the holes 76 which receive the various terminal pins. A complementary annular groove 78 is formed on the periphery of each pin - this is best seen in Figure 6. Each pin is forced into a hole 76 by means of a suitable press, and once the groove 78 and the rib 74 engage with each other the pin is securely attached to the base. This method of attaching the pins to the base is particularly attractive for it obviates the necessity of moulding the pins in situ to the base, or of using additional components to secure the pin to the base. In other respects, as previously indicated, the plugs 10 and 50 are similar to each other. Each plug dispenses with screws for securing the lid to the base, yet may be rapidly assembled or disassembled as desired. WHAT WE CLAIM IS:

1. An electrical plug which comprises a base, terminal pins supported by the base, and a lid, the base having a first member which projects from the body of the base into the interior of the assembled plug, the lid having a second member opposing the first member and projecting from the body of the lid into the interior of the assembled plug, the first and second members having formations which are located in the interior of the assembled plug and which are interengageable releasably to secure the lid to the base, and the base having a hole formed in it so that suitable means may be inserted into the. hole and operated to disengage the interengaged formations.

2. An electrical plug according to claim 1 in which at least one of the first and second members is made from a suitable material so that its formation is resiliently deflectable from and subsequently engageable with the formation on the other member as the lid and the base are pressed together.

3. An electrical plug according to claim 1 or 2 in which at least one terminal pin has a screw at an oblique angle to the longitudinal axis of the pin for connecting an electrical conductor to the pin.

4. An electrical plug according to any one of claims 1 to 3 in which each pin has a groove formed in its periphery, the groove being engageable with a complementary rib on the base to secure the pin to the base.

5. An electrical plug according to claim 4 in which the groove in each pin is annular and extends round the periphery of the pin.

6. An electrical plug according to any one of claims 1 to 5 in which the base and the lid are made from polycarbonate.

7. An electrical plug according to any one of claims 1 to 6 in which the terminal pins are slidably supported by the base, the lid includ

ing formations which bear on the pins when the lid is secured to the base to prevent movement of the pins relatively to the base.

8. An electrical plug substantially as herein described with reference to Figures 1 to 3 or Figures 4 to 6 of the accompanying drawings.