ELECTRIC PLUGS

Abstract: An electric plug (1) having a cover portion (2) and a base portion (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 one of the terminals (5), and secured therein by a resiliently loaded clamping means or a screw attachment. The screw (6) and the terminals (5) are both operable by being gripped between a person's thumb and first finger thereby eliminating the need for a screwdriver.

Description: 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 to 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 hereinbeiow have the advantage that they can be dismantled and electric conductors can be connected to the terminals directly by hand without the use of 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 portion and a base portion, the base portion being provided with terminal pins extending from an outer face thereof, each of said pins being electrically connected to a separate terminal and each terminal being attached to an inner face of the base portion, the electric plug being characterised in that the cover portion is detachably secured to the base portion by means of a screw having a head portion disposed in a recess in the outer face of the base portion, the head portion being provided with a gripping portion which can be gripped between a person's thumb and first finger such that the screw can be rotated by hand, thereby enabling the cover portion to be detached or attached to the base portion, said plug also being provided with an inlet for an electrical conductor having a plurality of conducting cores each of which may be received in a respective one of the terminals and secured thereto. The cover portion and/or the base portion of the electric plug are preferably made from a rigid material so that when the cover portion is attached to the base portion 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 portion, the leaf spring urging the electrical conductor towards the base portion of the electric plug. Each terminal preferably comprises an electrically conducting support member having an aperture disposed centrally so that it may receive one of the conducting cores of the electrical conductor, and the conducting support member is electrically connected to one of the pins of the plug. The core may be secured within the aperture of the support member by means of a bar which forms part of an outer sleeve, the outer sleeve being slidably mounted over the conducting support member. The bar is urged towards the core of the electrical conductor by a resilientiy loaded clamping means, which preferably comprises a spring or springs, one end of which is connected to the outer sleeve, and the other end being connected to the support member. Alternatively, the core may be secured within the aperture or a recess in the support member by means of a screw attachment which can be screwed into the support member so as to cause the conducting core to be securely gripped between the screw attachment and the support member. In this case, the screw attachment preferably has a screw head sufficiently large for the head to be tightly gripped between, for example, a person's thumb and first finger, thereby enabling the screw attachment to be screwed into the support member without the aid of a screwdriver. Some embodiments of the present invention will now be described, by way of examples, 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 an enlarged plan view from above of an example of a terminal within the electric plug; Figure 4 shows a side view of the terminal of Figure 3; and Figures 5A and 5B each show an enlarged side view of an alternative form of terminal to that shown in Figures 3 and 4. Referring first to Figure 1, there is shown an electric plug 1 having a cover portion 2, a base portion 3 provided with terminal pins 4 extending from one outer face. Each of the pins 4 is in electrical contact with a separate terminal 5 attached to the inner side of the base 3. In Figure 1, only one terminal 5 is shown. As shown in Figure 1, the cover portion 2 is attached to the base portion 3 by means of a screw 6, which has a head portion 7 disposed in a recess 8 provided in the outer face of the base portion 3 from which the pins 4 extend. The screw 6 extends through the base portion 3, and is screwed into the cover portion 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 of 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 portion 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 screw 6. 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 portion 2 and the base portion 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 portion 2, the leaf spring 14 urging the electrical conductor 9 towards a projection 15 situated on the base portion 3. The screw 6 is situated adjacent to the inlet 12, therefore being easily accessible 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 an example of one of the terminals 5. The terminal 5 is cyliπdrically 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 Figures 3 and 4, the terminal 5 comprises a conducting support member 20 which is electrically connected to one of the pins 4, and attached to the base portion 3. The conducting support member 20 has an aperture 21 through which extends the core 10 of the electrical conductor 9. The aperture 21 lies along a diameter of the conducting support member 20, 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 JO 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 spring 24 5 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 obscure 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, 2Q 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 25 member. Figure 5A shows one example of an alternative form of terminal 5. In this case, the terminal 5 comprises a conducting support member 20'. The support member 20' is constructed similarly to the support member 20 except that the core 10 is secured in the aperture 21 by means of a screw jg attachment 24. The screw attachment 24 has a head 25 which is sufficiently large for the head 25 to be tightly gripped between, for example, a person's thumb and first finger. Therefore, the screw attachment 24 can be screwed into the support member 20', so that the core 10 can be securely gripped in the terminal 5, via a threaded hole 26 in the support member 20' without the 35 aid of a screwdriver or other tool. OMH Figure 5B shows a further example of the terminal 5. The core 10 is secured in the terminal 5 by means of a screw attachment 24', which operates according to the same principle as the screw attachment 24. In this case, the terminal 5 comprises a support member 20" which receives the core 10 in a recess 27. The screw attachment 24' comprises a screw head 28 which is sufficiently large for the head 28 to be tightly gripped between a person's thumb and first finger, thereby enabling the screw attachment 24' to secure the core 10 in the terminal 5 by gripping the core 10 between a washer 29 and the support member 20". The above described arrangements are 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. It will be appreciated that the electric plug can be provided with a cartridge type fuse.

Claims: CLAIMS 1 An electric plug comprising a cover portion and a base portion, the base portion being provided with terminal pins extending from an outer face thereof, each of said pins being electrically connected to a separate terminal and each terminal being attached to an inner face of the base portion, the electric plug being characterised in that the cover portion (2) is detachably secured to the base portion (3) by means of a screw (6) having a head portion (7) disposed in a recess (8) in the outer face of the base portion, the head portion (7) being provided with a gripping portion (11) which can be gripped between a person's thumb and first finger such that the screw (6) can be rotated by hand, thereby enabling the cover portion (2) to be detached or attached to the base portion (3), said plug (1) also being provided with an inlet (12) for an electrical conductor (9) having a plurality of conducting cores (10) each of which may be received in a respective one of the terminals (5) and secured thereto. 2 An electric plug according to claim 1, in which the cover portion (2) and the base portion (3) are provided with wall portions (13) which are urged against the electrical conductor (9), so as to act as a cable grip, when the cover portion is secured to the base portion by means of the screw (6). 3 An electric plug according to claim 1 or claim 2, in which a leaf spring (14) is provided adjacent to the inlet (12), the leaf spring providing a means for urging the electrical conductor (9) towards the base portion (3), 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 (5) each comprise a conducting support member (20) having an aperture (21) for receiving the core (10) of the electrical conductors (9), and an outer sleeve (22) having a bar (23), the outer sleeve (22) being siidably mounted over the support member (20) so that when the conducting core (10) is received in the aperture (21), a resiliently loaded clamping means (24) associated with the support member (30) and the outer sleeve (22) urges the bar (23) against the conducting core (10) thereby securing the core to the terminal (5). ϊ jRE $ OMPI 5 An electric plug according to claim 4, wherein the resilientiy loaded clamping means comprises a spring or springs (24) connected at one of their ends to the outer sleeve (22), and connected at their other ends to the support member (20). 6 An electric plug according to claim 1, claim 2, or claim 3, in which the terminals (5) each comprise a conducting support member (20') associated with a screw attachment (24) which can be screwed into the support member so as to secure the core to the terminal, the screw attachment being provided with a screw head (25) sufficiently large for the screw attachment to be operable by being gripped and rotated by a person's thumb and first finger. «

Inventors: COLLINS WARWICK IAN, COLLINS, WARWICK, IAN
Applicants: COLLINS WARWICK IAN, COLLINS, WARWICK, IAN
Application year: 1983
Main classification: H01R13
IPC codes: H01R4, H01R13