GB2109178A

GB2109178A - Electric plugs

Info

Publication number: GB2109178A
Application number: GB08229856A
Authority: GB
Inventors: Warwick Ian Collins
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-26
Filing date: 1982-10-19
Publication date: 1983-05-25
Also published as: GB2109178B

Abstract

An electric plug (1) having a cover (2) and a base (3) is provided with pins (4). Each of the pins (4) is electrically connected to a separate terminal (5). The cover (2) is detachably secured to the base (3) by means of at least one screw (6) having a head portion (7) disposed in a recess (8) on the base (3). The head portion (7) is provided with a gripping portion (11) which can be gripped between a person's thumb and forefinger such that the screw (6) can be rotated, thereby enabling the cover (2) to be detached or attached to the base (3). The plug is also provided with an inlet (12) for an electrical conductor (9) having a plurality of conducting cores (10), each of which may be received into an aperture (21) in one of the terminals (5), and secured within the aperture (21) by a clamping means comprising a pair of springs which cause a portion of a terminal cap(s) to press against each core. The screw (6) and the terminal (5) are both operable by being gripped between a person's thumb and forefinger thereby eliminating the need for a screwdriver. <IMAGE>

Description

SPECIFICATION Electric plugs This invention relates to electric plugs.

Conventional electric plugs, particularly electric wall plugs, require the use of a screwdriver or other tool so that access may be gained to its terminals and also for connecting electrical conductors to the terminals. This is disadvantageous because the process of dismantling the plug and then connecting the electric conductor from the terminals is time consuming, and it is necessary that one has the correct sized screwdriver or other appropriate tool.

Electric plugs embodying the invention and as described hereinbelow have the advantage that they can be opened and electric conductors can be connected to the terminals directly by hand without using a screwdriver or any other tool. Hence, the time required to connect the electric conductors is significantly reduced and the process becomes much more simple. Furthermore, such electric plugs are simpler to connect up to electric cables and therefore they are more likely to be connected correctly hence increasing safety.

According to the present invention there is provided an electric plug comprising a cover and a base, the base being provided with terminal pins extending from one face thereof, each of said pins being electrically connected to a separate terminal each having a resiliently loaded clamping means, each terminal being attached to the opposite side of the base, the cover being detachably secured to the base by means of a screw having a head portion disposed in a recess on the one face, the head portion being provided with a gripping portion which can be gripped between a person's thumb and forefinger such that the screw can be rotated, thereby enabling the cover to be detached or attached to the base, the plug also being provided with an inlet for an electrical conductor having a plurality of conducting cores each of which may be received in an aperture in one of the terminals and secured within the aperture by the resiliently loaded clamping means.

The cover and/or the base of the electric plug are preferably made from a rigid material so that when the cover is attached to the base by means of the screw, a wall portion disposed at the inlet of the plug is urged against the electrical conductor so as to act as a cable grip. An additional cable gripping means may be provided by a leaf spring attached to the cover, the leaf spring urging the electrical conductor towards the base of the electric plug. Each terminal preferably comprises an electrically conducting support member having the aperture disposed centrally so that it may receive one of the conducting cores of the electrical conductor.The conducting support member is electrically connected to one of the pins of the plug, and the core is secured within the aperture of the support member by means of a bar which forms part of an outer sleeve, slidably mounted over the conducting support member. The bar is urged towards the core of the electrical conductor by the clamping means, which preferably comprises a spring or springs, one end of which are connected to the outer sleeve, and the other end being connected to the support member.

The present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a part sectional view of an electric plug embodying this invention; Figure 2 shows a plan view from below of the electric plug of Figure 1; Figure 3 shows a plan view from above of a terminal within the electric plug; and Figure 4 shows a side view of the terminal of Figure 3.

Referring first to Figure 1,there is shown an electric plug 1 having a cover 2, a base 3 provided with pins 4 extending from one face. Each of the pins 4 is in electrical contact with a separate terminal 5 attached to the opposite side of the base 3. In Figure 1, only one terminal 5 is shown. As shown in Figure 1,the cover 2 is attached to the base 3 by means of a screw 6, which comprises a head portion 7 disposed in a recess 8 in the face of the base 3 from which the pins 4 extend. The screw 6 passes through the base 3, and is screwed into the cover 2 by rotating the head portion 7. Figure 1 also shows an electrical conductor 9 which has three conducting cores 10, one of which is secured in the terminal 5.

Figure 2 shows a plan view from below the electric plug of Figure 1. The head portion 7 is shown to be provided with a gripping portion 11 designed so that it can be gripped between, for example, a person's thumb and forefinger, whereby it can be rotated, thus causing the screw 6 to rotate. Hence, the cover 2 of the electric plug 1 can be detached from the base 3 simply by gripping the gripping portion 11 between the thumb and forefinger and rotating.

The electrical conductor 9 passes into the electric plug 1 via an inlet or aperture 12 (see Figure 1). The inlet or aperture 12 is situated between walls 13 of the cover 2 and the base 3, the faces of the walls 13 at the inlet 12 abutting against the electrical conductor 9 so that they act as a cable grip when the screw 6 is tightened. An additional cable gripping means is provided by a leaf spring 14 which is attached to the cover 2, the leaf spring 14 urging the electrical conductor 9 towards a projection 15 situated on the base 3. The screw 6 is situated adjacent to the inlet 12, therefore being easily accessable by a person's thumb and forefinger. Figure 1 also shows a lip arrangement 16 disposed at a portion of the plug 1 remote from the inlet 12.The lip arrangement 16 allows the cover 2 and the base 3 to interlock together at the portion remote from the inlet 12, thus ensuring a secure attachment between the cover 2 and the base 3.

Figure 3 shows a plan view from above of one of the terminals 5. The terminal 5 is cylindrically shaped, and arranged so that it is capable of clamping a core 10 of the conductor 9 without the need for a screwdriver or other tool. As shown in Figure 3, the terminal 5 comprises a conducting support member 20 which is electrically connected to one of the pins 4, and attached to the base 3. The conducting support member 20 comprises an aperture 21 through which passes the core 10 of the electrical conductor 9. The aperture 21 lies along a diameter of the conducting support member, thus defining a longitudinal axis. The terminal 5 also comprises an outer sleeve 22, which is slidably mounted over the conducting support member 20.

Inside the outer sleeve 22, there is a bar 23 arranged so that it fits within a recess (not shown) of the conducting support member 20. The bar 23 has a longitudinal axis disposed transversely to the longitudinal axis of the aperture 21. The conducting support member 20 and the outer sleeve 22 are coupled together by means of a pair of springs 24.

As shown in Figure 4, one end of each of the springs 24 is attached to the support member 20 and the other ends of each of the springs 24 are attached to the outer sleeve 22. The spring constant of the springs 24 is such that when there is no core 10 disposed in the aperture 21, the outer sleeve 22 is urged in the direction of arrow A, thereby causing the bar 23 to obsecure the passage through the aperture 21. The core 10 is inserted into the aperture 21 by raising the outer sleeve 22, against the action of the springs 24, by gripping the outside of the outer sleeve between, for example, the thumb and forefinger. Hence, the bar 23 rises, thereby opening the aperture 21. Then, the cable 10 is inserted into the aperture 21 and the outer sleeve 22 is then released, whereby it is urged against the core 10 by means of the springs 24 thereby forming a clamping means.

The springs 24 may be replaced by a single spring or by any other suitable resilient member.

The above described embodiment is in terms of a 13 amp plug such as one typically used in the home.

However, embodiments of this invention may be applied to other kinds of plugs and terminals to which access is required without the need for a screwdriver or other tool.

Claims

1. An electric plug comprising a cover and a base, the base being provided with terminal pins extending from one face thereof, each of said pins being electrically connected to a separate terminal each having a resiliently loaded clamping means, each terminal being attached to the opposite side of the base, the cover being detachably secured to the base by means of a screw having a head portion disposed in a recess on the one face, the head portion being provided with a gripping portion which can be gripped between a person's thumb and forefinger such that the screw can be rotated, thereby enabling the cover to be detached or attached to the base, the plug also being provided with an inlet for an electrical conductor having a plurality of conducting cores each of which may be received in an aperture in one of the terminals and secured within the aperture by the resiliently loaded clamping means.

2. An electric plug according to claim 1, in which the cover and the base are provided with wall portions which are urged against the electrical conductor, so as to act as a cable grip, when the cover is secured to the base by means of at least one screw.

3. An electric plug according to claim 1 or claim 2, in which a leaf spring is provided adjacent to the inlet, the leaf spring providing a means for urging the electrical conductor towards the base, so as to act as a cable grip.

4. An electric plug according to claim 1, claim 2 or claim 3, in which the terminals comprise a conducting support member having the aperture, the support member being in electrical contact with one of the pins of the plug, and an outer sleeve having a bar, the outer sleeve being slidably mounted over the support member so that when a conducting core is received by the aperture, the bar is urged towards the conducting core by the clamping means.

5. An electric plug according to claim 4, wherein the resilient loading of the clamping means comprises a spring or springs connected at one of their ends to the outer sleeve, and connected at their other ends to the support member.

6. An electric plug substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.