GB2126805A

GB2126805A - Electrical plug

Info

Publication number: GB2126805A
Application number: GB08324363A
Authority: GB
Inventors: Robert Brooks Wilson
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-09-10
Filing date: 1983-09-12
Publication date: 1984-03-28
Also published as: GB8324363D0

Abstract

An electrical plug (1) comprises a housing having an upper part (2) connected to a lower part (3). Three electrical pins (4a, 4b, 4c) project through apertures provided in the lower face of the plug. The pins can be received in an electrical socket, and can be connected to a wire (5) which can deliver an electrical supply to an electrical appliance. A locking mechanism is provided and is movable between a locked position and an unlocked position by a key (21). In the locked position the lower part and the upper part are prevented from being separated, and pin (4a) is electrically disconnected from the wire (5). <IMAGE>

Description

SPECIFICATION Electrical plug This invention relates to an electrical plug.

According to one aspect of the invention there is provided an electrical plug comprising a housing having an upper part connected to a lower part, at least two electrical pins projecting from a face of said housing, said pins being receivable in an electrical socket, and said pins being connectible to means for delivering electrical supply to an electrical appliance, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position the upper part and the lower part are prevented from being separated, and at least one pin is electrically disconnected from the means for delivering the electrical supply.

According to another aspect of the invention there is provided an electrical plug comprising a housing having an upper part connected to a lower part, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position the lower part and upper part are prevented from being separated.

According to another aspect of the invention there is provided an electrical plug comprising a housing, at least two electrical pins projecting from a face of said housing, said pins being receivable in an electrical socket, and said pins being connectible to means for delivering an electrical supply to an electrical appliance, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position at least one pin is electrically disconnected from the means for delivering the electrical supply.

Advantageously, the locking mechanism is pivotally connected to the inside of the upper part.

Preferably the pins project through apertures provided in the lower part of the housing.

Desirably the means for delivering the electrical supply is connected to a first terminal provided in the lower part of the plug, said first terminal being electrically disconnected from each pin, when the locking mechanism is in the locked position.

In one embodiment the locking mechanism is provided with an electrical contact. The electrical contact can abut against the first terminal and against a second terminal electrically connected to at least one pin when the locking mechanism is in the unlocked position, thereby permitting electrical current to flow between the pin and the first terminal, through the electrical contact.

In another embodiment the first terminal and one pin are electrically connected to a microswitch, and if desired may be connected to the microswitch by a plug. The locking mechanism can actuate the microswitch when in the unlocked position, thereby permitting electrical current to flow between the pin and the terminal.

It is preferable that a locking tab is rigidly connected to the lower part. The locking tab is desirably provided with a recess which can receive an arm of the locking mechanism when the locking mechanism is in the locked position, thereby preventing the separation of the lower part from the upper part.

The electrical plug of the present invention has many advantages over prior art plugs. The provision of means to prevent the separation of the upper and lower parts prevents the plug being taken apart and tampered with.

Moreover the plug may only be used for the purposes of supplying electricity by a person who can lock or unlock the locking mechanism, i.e. a person in possession of a key. This can be useful in domestic applications where, for safety purposes, it may be desirable to prevent children from operating electrical appliances without supervision.

The electrical plug of the present invention is also useful for industrial applications where it may be necessary to restrict the use of some electrical appliance to particular people.

Reference is now made to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of an electrical plug according to the invention; Figure 1 a is an elevation of a key for the plug illustrated in Figure 1; Figure 2 is a section along the lines 2-2 of Figure 1; Figure 3 is a section along the lines 3-3 of Figure 1: Figure 4 is a perspective view of an alternative embodiment of an electrical plug according to the present invention; Figure 5 is a section along the lines 5--5 of Figure 4, showing the locking mechanism in the locked position, omitting the details of the lower part of the plug; and Figure 6 is a section along the lines 5-5 of Figure 4, showing the locking mechanism in the unlocked position, omitting the details of the lower part of the plug.

In Figures 1 to 3 a plug generally designated 1 comprises an upper part 2 and a lower part 3.

Three electrical pins 4a, 4b and 4c project from the lower part 2 and are adapted to be received respectively in a neutral, live and earth terminal of an electrical socket. A composite wire 5 extends from the plug 1 and provides a means to connect and electrical supply from the plug to an electrical appliance (not shown). The composite wire includes live, neutral and earth wires designated 5a, 5b and Sc respectively.

A screw 6 passes through the lower part 3 and can be received in a hole 7 provided in the upper part 2. The screw 6 can hold the upper part 2 and the lower part 3 together.

The live pin 4b is connected to a fuse 8 which is in connected to an electrical terminal 9. The live wire 5a is connected to an electrical terminal 10.

Electrical terminals 11 and 12 are provided in the upper part 2 of the plug 1. When the upper part 2 and the lower part 3 are assembled as illustrated in Figure 1, then terminal 9 makes electrical contact with terminal 11, and terminal 10 makes electrical contact with terminal 12. If desired the terminals 9 and 11 may be integral and the terminal 10 and 12 may be integral.

A locking tab 13 is attached to the lower part 3, and the locking tab extends into the upper part 2 as shown in Figure 3.

A locking mechanism 14 is provided in the upper part 2. The locking mechanism 14 includes an arm 15, an electrical contact 1 6 and a lug 17.

The locking mechanism 1 4 can pivot about an axis which passes perpendicularly through aperture 18. A spring 20 keeps the mechanism biased in the position illustrated in Figure 3.

The locking mechanism may be actuated by means of a key 21. The key includes a locating lug 22 adapted to be received in aperture 18, and further includes a lug 23 adapted to abut against lug 17.

In Figure 3 the locking mechanism is shown in the unlocked position. It is clear from Figure 3 that no electrical contact exists between the terminals 9 and 1 0. Furthermore a recess 1 3a is provided in the locking tab 13 into which the arm 1 5 can be received, which prevents the separation of the upper part 2 from the lower part 3.

Additional lugs 24 are provided in the upper part 2 which receive corresponding projections (not shown) in the lower part 3 so that the upper part 2 and the lower part 3 cannot be separated when the arm 1 5 is received in the recess 1 3a.

The key 21 may be inserted through an aperture 2a provided in the upper part 2. The locating lug 22 is received in aperture 1 8 and the key may then be rotated in a clockwise direction.

The lug 23 on the key 21 is positioned such that it will abut against lug 17 when the key has been turned through approximately 450.

Further rotation of the key causes the locking mechanism to move to the unlocked position in which contact 1 6 makes electrical contact with terminals 11 and 1 2 thereby permitting an electrical current to flow from the live pin 4b to the terminal 10. Simultaneously the arm 1 5 is removed from the recess 1 3a thereby permitting the upper part 2 and the lower part 3 to be separated by unscrewing the screw 7.

Any conventional and known means can be provided to hold the locking mechanism in the locked position against the force exerted by spring 20 until the key 21 is removed. For example, a spring loading device can be provided at aperture 18.

An alternative embodiment of the invention is illustrated in Figure 4 to 6. Many of the components of the alternative embodiment are identical to those shown in Figure 1 to 3. In view of this like components are designated by like reference numerals.

A plug generally designated 101 comprises an upper part 102 and a lower part 103. The lower part 103 is substantially identical to the lower part 3 illustrated in Figures 1 to 3 and therefore has not been shown in detail. The upper part is provided with two electrical terminals 111 and 112 and when the upper part 102 and the lower part 103 are assembled the terminals 111 and 112 can make contact with terminals 9 and 10 respectively of the lower part 103. If desired the terminals 9 and 111 may be integral, and the terminals 10 and 112 may be integral.

A locking mechanism 11 4 includes an arm 115, an electrical contact 11 6 and a push lever 1 30. The push lever 1 30 is pivotally mounted on the locking mechanism 114 at pivot point 131, and a spring 132 is provided between the push lever 130 and the locking mechanism 114. The push lever is biased in the locked position shown in Figure 5 by means of a spring 120. The locking mechanism 114 can pivot about a pivot point 118.

The locking mechanism 114 can be actuated by means of a key 121 which is inserted through an aperture 1 02a provided in the side of the upper part 102.

When the key 1 21 is inserted through the aperture 1 02a a stem 122 of the key abuts against the push lever 130. Insertion of the key 121 pushes the locking mechanism into the unlocked position illustrated in Figure 6 where current can flow from the live terminal 4b to terminal 10, and the upper part 102 and the lower part 103 may be separated.

The key may be tumed in a lock 133 to retain the locking mechanism in the locked position.

A number of modifications to the electrical plug are possible. For example the upper part 2,102 of the plug may be provided in two parts, a top part and a base part. In addition the terminals 11, 12 and contact 1 6 may be replaced by a microswitch.

In this embodiment the pivoting of the locking mechanism 14 causes a microswitch to be actuated which allows electrical current to flow from the live pin 4b to terminal 10.

Claims

1. An electrical plug comprising a housing having an upper part connected to a lower part, at least two electrical pins projecting from a face of said housing, said pins being receivable in an electrical socket, and said pins being connectible to means for delivering electrical supply to an electrical appliance, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position the upper part and the lower part are prevented from being separated, and at least one pin is electrically disconnected from the means for delivering the electrical supply.

2. An electrical plug according to Claim 1 in which the locking mechanism is pivotally connected to the inside of the upper part.

3. An electrical plug according to Claim 1 or 2 in which the pins project through apertures provided in the lower part of the housing.

4. An electrical plug according to Claim 1,2 or 3 in which the means for delivering the electrical supply is connected to a first terminal provided in the lower part of the plug, said terminal being electrically disconnected from each pin when the locking mechanism is in the locked position.

5. An electrical plug according to any preceding claim in which the locking mechanism is provided with an electrical contact.

6. An electrical plug according to Claims 4 and 5 in which the electrical contact can abut against the terminal and against a second terminal electrically connected to at least one pin when the locking mechanism is in the unlocked position, thereby permitting electrical current to flow between the pin and the first terminal, through the electrical contact.

7. An electrical plug according to Claim 4 in which the first terminaland one pin are electrically connected to a microswitch.

8. An electrical plug according to Claim 7 in which the locking mechanism can actuate the microswitch when in the unlocked position, thereby permitting electrical current to flow between the pin and the first terminal.

9. An electrical plug according to any preceding claim in which a locking tab is rigidly connected to the lower part.

10. An electrical plug according to Claim 9 in which the locking tab is provided with a recess which can receive an arm of the locking mechanism when the locking mechanism is in the locking position, thereby preventing the separation of the lower part from the upper part.

11. An electrical plug according to any preceding claim in which the locking mechanism may be moved from the locked position to the unlocked position by a key.

1 2. An electrical plug according to Claim 11 in which an aperture is provided in a top face of the upper part to receive the key.

1 3. An electrical plug according to Claim 11 in which an aperture is provided in a side face of the upper part to receive they key.

14. An electrical plug substantially as herein described with reference to and as shown in the accompanying drawings.

1 5. An electrical plug comprising a housing having an upper part connected to a lower part, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position the lower part and the upper part are prevented from being separated.

1 6. An electrical plug comprising a housing, at least two electrical pins projecting from a face of said housing, said pins being receivable in an electrical socket, and said pins being connectible to means for delivering an electrical supply to an electrical appliance, and a locking mechanism movable between a locked position and an unlocked position, wherein in said locked position at least one pin is electrically disconnected from the means for delivering the electrical supply.