FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF INVENTION
An electrical socket and switch assembly
INVENTOR
Name : Phase Shantanu Purushottam
Nationality : Indian National
Address : Crompton Greaves Limited, Switchgear-6 & Power Quality Business, D2, MIDC, Waluj, Aurangabad, Maharashtra, India
APPLICANTS
Name : CROMPTON GREAVES LIMITED
Nationality: Indian Company
Address : CG House, Dr Annie Besant Road, Prabhadevi, Mumbai 400025, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF INVENTION
This invention relates to an electrical socket and switch assembly.
BACKGROUND OF INVENTION
An electrical appliance, equipment or machine such as electric iron, mixer / grinder, refrigerator or welding machine is associated with a cable cord provided with a plug pin at the distal end thereof and is connected to a power supply by inserting the plug pin in the terminal barrels in the socket base of a socket and switch assembly already connected to the power supply. The plug pin can be inserted in the terminal barrels in the socket base both in the turned on and turned off positions of the switch as the terminal barrels in the socket base are exposed and accessible to the plug pin in both the positions of the switch. If the plug pin is introduced in the terminal barrels in the socket base in the turned on position of the switch, there can be sparking due to shorting. Sparking can cause fire accidents and/or damage to the appliance, equipment or machine. In the turned on position of the switch, if a person accidentally happens to insert a thin conductor material strip or wire or a child out of curiosity puts fingers into the terminal barrels in the socket base, the person or child, as the case may be, can experience an electrical shock the consequences of which can be fatal. In order to prevent access into the terminal barrels in the socket base, it is known to provide between the socket base and front cover of the socket and switch assembly an insulating material sheet compression spring biased vertically down. The insulating material sheet covers the terminal barrels in the socket base only partially at the bottom thereof. Generally the sheet partially covers one of the terminal barrels in the case of a two pin plug or the terminal barrel
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corresponding to the neutral pin in the case of a three pin plug so as to facilitate introduction of the plug pin in the terminal barrels initially. On pushing the plug pin into the terminal barrels in the socket base, the sheet moves up under compression of the spring and allows the plug pin to enter the terminal barrels fully. In the case of a electrical socket and switch assembly comprising the spring biased sheet also, the plug pin can be introduced in the terminal barrels both in the turned on and turned off positions of the switch and, therefore, accidents and damage can still occur as explained above.
OBJECTS OF INVENTION
An object of the invention is to provide an electrical socket and switch assembly which prevents insertion and removal of the plug pin in the turned on position of the switch and allows the plug pin to be inserted in the socket only in the turned off position of the switch thereby imparting safety to the assembly and preventing accidents and damages.
Another object of the invention is to provide an electrical socket and switch assembly which eliminates the conventional spring biased insulating material sheet.
DETAILED DESCRIPTION OF INVENTION
According to the invention there is provided an electrical socket and switch assembly comprising an insulating material shutter transversely slidably disposed between the socket base and the front cover of the said assembly, the shutter being compression
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spring biased at one side in the direction of the switch of the said assembly and provided with a lateral arm at the opposite side thereof, the outer end of the lateral arm being tapered, the shutter being further provided with openings in the same lay out as the terminal barrels in the socket base and terminal mouths in the front cover of the said assembly, the openings in the shutter being slightly larger than the terminal barrels and terminal mouths, the pins of the plug pin to be inserted in the terminal barrels in the socket base corresponding to the terminal barrels and terminal mouths and being provided with circumferential grooves at the base thereof corresponding to the thickness of the shutter, the shutter being adapted to lie displaced in the direction of the switch in the turned on position of the switch with the tapered outer end of the lateral arm engaged in the gap between the non-contact making end of the movable part of the switch and corresponding end of the switch base and the openings in the shutter completely moved away from the terminal barrels in the socket base and terminal mouths in the front cover under the expansive force of the compression spring and to lie displaced in the direction of the compression spring in the turned off position of the switch with the tapered outer end of the lateral arm abutting against the non-contact making end of the movable part of the switch closed against the corresponding end of the switch base and the openings in the shutter aligned with the terminal barrels in the socket base and terminal mouths in the front cover under compression of the compression spring.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
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Fig 1 is an exploded view of an electrical socket and switch assembly including a plug pin with the switch in the turned on position according to an exemplary embodiment of the invention;
Fig 2 is a view from the backside of the front cover of the electrical socket and switch assembly of Fig 1 in its assembled form with the switch in the turned on position and without the plug pin inserted in the socket;
Fig 3 is front elevation of the electrical socket and switch assembly of Fig 1 in its assembled form with the switch in the turned on position and without the plug pin inserted in the socket;
Fig 4 is a view from the backside of the front cover of the electrical socket and switch assembly of Fig 1 in its assembled form with the switch in the turned on position and the plug pin inserted in the socket;
Fig 5 is an isometric view of the plug pin in Fig 1;
Fig 6 is an exploded view of the electrical socket and switch assembly of Fig 1 with the switch in the turned off position;
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Fig 7 is a view from the backside of the front cover of the socket and switch assembly of Fig 1 in its assembled form with the switch in the turned off position and without the plug pin inserted in the socket;
Fig 8 is front elevation of the socket and switch assembly of Fig 1 in its assembled form with the switch in the turned off position and without the plug pin inserted in the socket; and
Fig 9 is a view from the backside of the front cover of the socket and switch assembly of Fig 1 in its assembled form with the switch in the turned on / off position and the plug pin inserted in the socket.
The electrical socket and switch assembly 1 as illustrated in Figs 1 to 9 of the accompanying drawings comprises a base cover 2 fitted with a front cover 3 using screws 4 engaged in screw holes 5 in the front cover and corresponding screw holes 6 in the base cover. 7 and 8 are a socket base and a switch base, respectively. The movable part of the switch is marked 9 and is accessible through the slot 10 provided in the front cover. The contact making and non-contact making ends of the movable part of the switch are marked 9a and 9b, respectively. The terminal barrels in the socket are marked 11a, lib and lie and terminal mouths in the front cover corresponding to the terminals barrels in the socket base are marked 12a, 12b and 12c. 13 is an insulating material shutter transversely slidably disposed between the socket base and front cover and between a pair of vertically spaced insulating material transverse guide members 14a, 14b fitted at
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the inner face of the front cover. The shutter is biased in the direction of the switch by compression spring 15 located in recess 16 formed at one side thereof. The shutter is provided with a lateral arm 17 at the opposite side thereof. The outer end of the arm is tapered and is marked 17a. The shutter is further provided with three openings 18a, 18b and 18c in the same layout as the terminal barrels 11a, lib and lie of the socket and terminal mouths 12a, 12b and 12c in the front cover. 19 is a plug pin comprising three pins 19a, 19b and 19c in the same lay out as the terminal mouths in the front cover, openings in the shutter and terminal barrels in the socket base. The pins of the plug pin are provided with circumferential grooves 20a, 20b and 20c at the base thereof corresponding to the thickness of the shutter. The pins of the plug pin correspond to the terminal barrels and terminal mouths. The switch terminals and their electrical connection to the terminal barrels in the socket base and to a power supply have not been illustrated and described as such are not necessary for understanding the invention. Similarly other parts and details of the socket and switch assembly also have not been illustrated and described as such are not necessary for understanding the invention. All the non-conducting parts of the socket and switch assembly including the shutter and transverse guide members are made of electrical guide insulating material such as electrical grade plastics such as acrylic.
On turning the switch on by pressing the contact making end 9a of the movable part of the switch against the corresponding end of the switch base, the non-contact making end 9b of the movable part of the switch moves away from the corresponding end of the switch base and the tapered outer end of the lateral arm moves into the gap formed
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between the non-contact making end of the movable part of the switch and the corresponding end of the switch base under the expansive force of the compression spring (Figs 1, 2 and 3). The openings 18a, 18b and 18c in the shutter are displaced and moved away from the terminal barrels 11a, lib and lie in the socket base and terminal mouths 12a, 12b and 12c in the front cover in the direction of the switch such that the openings 18a, 18b and 18c in the shutter are completely covered or overlapped by the front cover 3 thereby completely covering live terminal barrels in the socket base and preventing introduction of the plug pin or any thin conductor material strip or wire or fingers by a child in the terminal barrels in the socket base (Fig 3). On switching off the switch by pressing the non-contact making end 9b of the movable part of the switch against the tapered outer end of the lateral arm, the lateral arm and the shutter slides in the direction of the compression spring under compression of the spring and the non-contact making end of the of the movable part of the switch closes against the corresponding end of the switch base and the contact making end 9a of the movable part of the switch moves away from the corresponding end of the switch base thereby switching off the switch (Fig 6). The outer end of the lateral arm abuts against the non-contact making end of the movable part of the switch and the compression spring remains tensioned in the direction of the switch (Figs 7, 8 and 9). The openings 18a, 18b and 18c in the shutter are aligned with the terminal barrels 11a, lib and lie in the socket and terminal mouths 12a, 12b and 12c in the front cover and the plug pin is inserted in the terminal barrels in the socket base (Fig 9). The plug pin can be thus inserted in the terminal barrels in the socket base only in the turned off position of the switch. After inserting the plug pin in the terminal barrels in the terminal base, the switch is turned on
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by pressing the contact making end of the movable part of the switch against the corresponding end of switch base when the non-contact making end of the movable part of the switch moves away from the corresponding end of the switch base as described earlier. The shutter tends to move in the direction of the switch and the lateral arm tends to enter the gap between the non-contact making end of the movable part of the switch and the corresponding end of the switch base under the expansive force of the compression spring but the plug pins prevent movement of the shutter in the direction of the switch (Fig 4). At the same time the peripheries of the openings in the shutter enter the respective circumferential grooves at the base of the pins of the plug pin and prevent the plug pin from being removed from the terminal barrels in the socket base in the turned on position of the switch. In order to provide slight misalignment between the openings in the shutter and the terminal barrels in the socket and terminal mouths in the front cover and to ensure engagement of the peripheries of the openings in the shutter, the openings in the shutter are made slightly larger than the terminal barrels and terminal mouths by about 1 to 2 mm. The plug pin can be removed from the terminal barrels in the socket only after switching off the switch when the shutter is held spring tensioned against the non-contact making end of the movable part of the switch end and openings 18a, 18b and 18c in the shutter are fully aligned with the terminal barrels in the socket and terminal mouths in the front cover and the peripheries of the openings in the shutter are disengaged from the circumferential grooves at the base of the pins of the plug pin. According to the invention in order to insert the plug pin in the terminal barrels in the socket or remove the plug pin from the terminal barrels in the socket it is absolutely necessary that the switch should be turned off and it is not at all possible to insert the plug
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pin in the terminal barrels of the socket base and remove the plug pin from the terminal barrels of the socket base in the turned on position of the switch. The shutter covers and isolates the live terminal barrels in the socket base in switched on condition of the switch without the plug pin inserted therein. The socket and switch assembly of the invention has thus improved safety and it prevents accidents and damages likely to be caused by the conventional socket and switch assembly.
The plug pin can be two pin type with corresponding number of terminal barrels in the socket base and terminal mouths in the front thereof and openings in the shutter. The openings in the shutter can be circular, square or elliptical. Fitment of the base cover to a rigid surface, fitment of the front cover to the base cover and fitment of the switch base and socket base can be carried out in any known manner. The construction and configuration of the socket and switch can be any known construction and configuration. The base cover and front cover construction and configuration can vary. The shutter configuration and construction can vary. Variations in the construction and configuration of the socket and switch assembly including those in the construction and configuration of the shutter which will achieve the objects of the invention and are obvious to those skilled in the art are to be construed and understood to be within the scope of the invention.
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WE CLAIM
1 An electrical socket and switch assembly comprising an insulating material
shutter transversely slidably disposed between the socket base and the front cover of the said assembly, the shutter being compression spring biased at one side in the direction of the switch of the said assembly and provided with a lateral arm at the opposite side thereof, the outer end of the lateral arm being tapered, the shutter being further provided with openings in the same lay out as the terminal barrels in the socket base and terminal mouths in the front cover of the said assembly, the openings in the shutter being slightly larger than the terminal barrels and terminal mouths, the pins of the plug pin to be inserted in the terminal barrels in the socket base corresponding to the terminal barrels and terminal mouths and being provided with circumferential grooves at the base thereof corresponding to the thickness of the shutter, the shutter being adapted to lie displaced in the direction of the switch in the turned on position of the switch with the tapered outer end of the lateral arm engaged in the gap between the non-contact making end of the movable part of the switch and corresponding end of the switch base and the openings in the shutter completely moved away from the terminal barrels in the socket base and terminal mouths in the front cover under the expansive force of the compression spring and to lie displaced in the direction of the compression spring in the turned off position of the switch with the tapered outer end of the lateral arm abutting against the non-contact making end of the movable part of the switch closed against the corresponding end of the switch base and the openings in the shutter aligned with the terminal barrels in the socket base and terminal mouths in the front cover under compression of the compression spring.
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2 An electrical socket and switch assembly as claimed in claim 1, wherein the insulating material shutter is transversely slidably disposed between the socket base and the front cover of the said assembly between a pair of vertically spaced transverse guide members fitted at the inner surface of the front cover.
3 An electrical socket and switch assembly as claimed in claim 1 or 2, wherein the shutter and transverse guide members are made of electrical grade plastics such as acrylic.
4 An electrical socket and switch assembly as claimed in anyone of claims 1 to 3, wherein the openings in the shutter are circular, square or elliptical.
5 An electrical socket and switch assembly as claimed in anyone of claims 1 to 4, wherein the openings in the shutter are larger than the terminal barrels and terminal mouths by 1 to 2 mm.
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6 An electrical socket and switch assembly as claimed in any one of claims 1 to 5,
wherein the switch base comprises three terminal barrels and the shutter and front cover of the said assembly each comprises corresponding number of openings and terminal mouths, respectively and the plug pin comprises three pins.
Dated this 29th day of September 2006
(Prita Madan)
of Khaitan & Co
Agent for the Applicants
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