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 combination
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, worli, 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 combination.
BACKGROUND OF INVENTION
An electrical appliance, equipment or machine such as electric iron, mixer or grinder, refrigerator or welding machine is associated with a flexible 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 combination already connected to the power supply. The plug pin can be inserted in or removed from 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 easily accessible to the plug pin in the turned on and turned off positions of the switch. If the plug pin is introduced in or removed from 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 combination an electric insulator material slide compression spring biased vertically down. The slide covers the terminal barrels in the socket base only partially at the bottom thereof. Generally the slide partially covers one of the terminal barrels in the case of a two pin plug or the terminal barrel 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
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Fig 3 is back isometric view of the front cover of the socket and switch combination of Fig l;
Fig 4 is front isometric view of the shutter of the socket and switch combination of Fig 1;
Fig 5 is back isometric view of the movable part of the switch of the socket and switch combination of Fig 1;
Fig 6 is an enlarged view at X in Fig 1;
Fig 7 is front view of the socket and switch combination of Fig 1 in the switched on or switched off position of the switch without the plug pin inserted in the terminal barrels in the socket base; and
Fig 8 is front view of the electrical socket and switch combination of Fig 1 in the switched on or switched off position of the switch with the plug pin inserted in the terminal barrels in the socket base.
The electrical socket and switch combination 1 as illustrated in Figs 1 to 8 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 (Figs 1, 2 and 3). 7 is a socket base fixed to the front cover by screws (not shown) engaged through screw holes 8 in the socket base and tightened in screw holes 9 in bosses 10 protruding from the inner surface of the front cover. 11 is a switch base fixed to the front cover by screws (not shown) engaged
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through screw holes 12 in the switch base and tightened in screw holes 13 in bosses 14 protruding from the inner surface of the front cover. The movable part of the switch is marked 15 and is located in and accessible through the slot 16 provided in the front cover (Figs 1,2,3 and 5). The contact making and non-contact making ends of the movable part of the switch are marked 15a and 15b, respectively. The terminal barrels in the socket are marked 17 and the terminal mouths in the front cover corresponding to the terminals barrels in the socket base are marked 18. 19 is an electric insulator material shutter transversely slidably disposed between the socket base and front cover and biased by a pair of compression springs 20, 20 located in a pair of spaced apart oblong recesses 21,21 provided in the shutter at the outer surface thereof along the length thereof (Figs 1, 2 and 4). The springs are held compressed by a pair of stoppers 22, 22 provided at the inner side of the front cover (Figs 1, 2 and 3). Each of the stoppers is aligned with each of the oblong recesses and adapted to enter the recess and press against the respective springs. The shutter is provided with openings 23 in the same layout as the terminal barrels in the socket base and terminal mouths in the front cover. The openings in the shutter are slightly larger than the terminal barrels and terminal mouths and are provided with tapered portions (marked 23a) at their sidewalls at the switch side (Fig 4). The shutter is further provided with a tapered protrusion 24 at its end adjacent to the switch. The tapered protrusion is located at the front bottom surface of the shutter adapted to engage in a cavity 25 provided in the socket side sidewall of the slot 16 in the front cover (Fig 8). 26 is a notch provided in the contact making end 15a of the movable part of the switch (Fig 6). 27 is a plug pin comprising three pins 28 in the same layout as the terminal mouths in the front cover, openings in the shutter and terminal barrels in the socket base. 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 the other parts and details of the
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socket and switch combination 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 combination including the shutter are made of electric insulator material such as electric grade plastics such as acrylic. The openings in the shutter can be circular, square or elliptical. The openings in the shutter are larger than the terminal barrels in the socket base and terminal mouths in the front cover by about 1 to 2 mm. The tapered portions 23a in the sidewalls at the switch side of the openings in the shutter correspond to the transverse movement to be described by the shutter.
The switch is turned on and off in the usual manner. In the turned on position of the switch the contact making end 15a of the switch remains pressed against the respective end of the switch base and the non-contact making end 15b of the switch remains moved away from the respective end of the switch base. When the plug pin is not inserted in the terminal barrels of the socket, the shutter remains spring compressed against the respective stoppers 22 at the inner side of the front cover and displaced in the direction of the socket base (Fig 7). The shutter overlap and block the terminal barrels in the socket base and terminal mouths in the front cover leaving only the tapered portions in the switch side sidewalls of the openings in the shutter exposed for access to the pins of the plug pin. On introducing the plug pin in the exposed puter ends of the tapered portions of the openings in the shutter through the terminal mouths in the front cover and pushing the plug pin against the shutter, the pins of the plug pin slide in against the tapered potions of the openings and move the shutter transversely in the direction of the switch under expansion of the springs. At the extreme position of the shutter in the direction of the switch, the openings in the shutter will be aligned with the terminal barrels in the socket base and the pins of the plug pin will enter the terminal barrels (Fig 8). Simultaneously the tapered protrusion of the
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shutter adjacent the switch will move into the contact making end 15a of the movable part of the switch through the notch therein and engage in the cavity at the socket side sidewall of the slot in the front cover. While passing through the notch in the contact making end of the movable part of the switch, the tapered protrusion will trip and move away the contact making end of the movable part of the switch from the respective end of the switch base and switch off the switch. As the switch is automatically turned off during insertion of the plug pin in the turned off position of the switch sparking and fire accidents and damage due to sparking are prevented and the socket and switch combination of the invention has improved safety. In the turned on position of the switch, the terminal barrels and terminal mouths are thus fully covered by the shutter and the plug pin has to be introduced at the outer ends of the tapered portions in the socket side sidewalls of the openings in the shutter and pushed in intentionally and concisiously so as to insert the plug pin in the terminal barrels in the socket base. Accidents and damage which may occur due to introduction of any thin conductor material strip or wire or fingers by a child in the terminal barrels in the socket base in the turned on position of the switch are also thus avoid. The switch has to be intentionally and consciously turned on after inserting the plug pin in the terminal barrels in the socket base. The movement of the movable part of the switch for turning on and turning off the switch is not obstructed by the tapered protrusion engaged in the cavity in the socket side sidewall of the slot in the front cover as the tapered protrusion is flush with the cavity and does not project out of the cavity. On removing the plug pin from the terminal barrels in the turned on position of the switch, the shutter moves back in the direction of the socket base under compression of the springs. As the shutter moves in the direction of the socket base, the tapered protrusion disengages from the cavity at the socket side sidewall of the slot in the front cover and passes through the notch at the contact making end of the movable part of the switch. While passing through the notch at the contact making end of the movable part of
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the switch, the tapered protrusion of the shutter trips and moves away the contact making end of the movable part of the switch from the respective end of the switch base thereby switching off the switch. While removing the plug pin from the terminal barrels in the socket base also, the switch is thus automatically turned off so as to avoid arcing and fire accidents and damages. In the turned off position of the switch, the non contact making end of the movable part of the switch will remain pressed against the respective end of the switch base and the contact making end of the movable part of the switch will remain moved away from the respective end of the switch base. In the turned off position of the switch without the plug pin inserted in the terminal barrels in the socket base, the shutter will remain spring compressed and displaced in the direction of the socket base with the openings in the shutter misaligned with the terminal barrels and terminal mouths and the shutter overlapping and blocking the terminal barrels and terminal mouths as explained earlier (Fig 7). On introducing and pushing the plug pin into the terminal barrels in the socket base, the shutter will move in the direction of the switch under expansion of the springs and the tapered protrusion of the shutter adjacent the switch will enter and remain in the cavity in the socket side sidewall of the slot in the front cover (Fig 8). On removing the plug pin from the terminal barrels in the socket base, the shutter will move in the direction of the socket base to its original position under compression of the springs and the tapered protrusion will disengage from the cavity at the socket side sidewall of the slot in the front cover. During the movement of the shutter with the tapered protrusion in the direction of the switch and back in the direction of the socket base, the contact making end of the movable part of the switch remains moved away from the respective end of the switch base as the switch is turned off and provides no obstruction to the movement of the tapered portion of the shutter. The transverse sliding movement of the shutter in the direction of the switch and back in the direction of the
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socket base are limited by the tapered portions at the switch side sidewalls of the openings in the shutter and the compressive force of the springs.
The plug pin can be two pin type with corresponding number of terminal barrels in the socket base and terminal mouths in the front and openings in the shutter. 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. The number of springs for biasing the shutter can vary. Instead of tapered portions, other displacement means can be used for movement of the shutter. Instead of tapered protrusion and cavity and notch arrangement other tripping means can be used for tripping the movable part of the switch and switching off the switch. Variations in the construction and configuration of the socket and switch combination including those in the construction and configuration of the shutter and displacement means and tripping means 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 combination comprising an electric insulator material
shutter slidably disposed between the socket base and the front cover of the said combination, the
shutter being provided with openings in the same layout as the terminal barrels in the socket base
and terminal mouths in the front cover, the openings in the shutter being slightly larger than the
terminal barrels and terminal mouths, the shutter being spring compressed in the direction of the
socket base with the openings in the shutter misaligned with the terminal barrels and terminal
mouths and the shutter overlapping and blocking the terminal barrels and terminal mouths in the
absence of a plug pin inserted in the terminal barrels, displacement means for displacing the
shutter in the direction of the switch under expansion of the spring so as to align the openings in
the shutter with the terminal barrels and terminal mouths and to facilitate insertion of the plug
pin in the terminal barrels and tripping means for turning off the switch in the turned on position
thereof when the plug pin is inserted in the terminal barrels or removed therefrom.
2 An electrical socket and switch combination as claimed in claim 1, wherein the displacement means comprises tapered portions at the switch side sidewalls of the openings in the shutter corresponding to the transverse displacement to be described by the shutter.
3 An electrical socket and switch combination as claimed in claim 1 or 2, wherein the tripping means comprises a tapered protrusion provided at the front bottom surface of the shutter adjacent the switch adapted to pass through a notch in the contact making end of the movable part of the switch and engage in and disengage from a cavity provided in the socket side side wall of the slot in the fron cover for locating the movable part of the switch.
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4 An electrical socket and switch combination as claimed in any one of claims 1 to 3, wherein the insulator material shutter is spring compressed by a pair of compression springs located in a pair of spaced apart oblong recesses provided in the shutter at the outer surface thereof along the length thereof, the springs being held compressed by a pair of stoppers provided at the inner side of the front cover, each aligned with each of the oblong recesses and adapted to enter the oblong recesses and press against the respective springs.
5 An electrical socket and switch combination as claimed in anyone of claims 1 to 4, wherein the shutter is made of electrical grade plastics such as acrylic.
6 An electrical socket and switch combination as claimed in anyone of claims 1 to 5, wherein the openings in the shutter are circular, square or elliptical.
7 An electrical socket and switch combination as claimed in anyone of claims 1 to 6, wherein the openings in the shutter are larger than the terminal barrels in the socket base and terminal mouths in the front cover by 1 to 2 mm.
8 An electrical socket and switch combination as claimed in any one of claims 1 to 7, wherein the switch base comprises three terminal barrels and the shutter and front cover each comprises corresponding number of openings and terminal mouths, respectively and the plug pin comprises three pins.
Dated this 16th day of January 2007.
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Abstract
An electrical socket and switch combination (1) is provided. The combination comprises an electric insulator material shutter (19) slidably disposed between the socket base (7) and the front cover (3) thereof. The shutter is provided with openings (23) in the same layout as the terminal barrels (17) in the socket base and terminal mouths (18) in the front cover. The openings in the shutter are slightly larger than the terminal barrels and terminal mouths. The shutter is spring (20, 20) compressed in the direction of the socket base with the openings in the shutter misaligned with the terminal barrels and terminal mouths and the shutter overlapping and blocking the terminal barrels and terminal mouths in the absence of a plug pin (27) inserted in the terminal barrels. Displacement means comprising tapered portions (23a) are provided in the sidewalls of the openings in the shutter for displacing the shutter in the direction of the switch under expansion of the spring so as to align the openings in the shutter with the terminal barrels and terminal mouths and to facilitate insertion of the plug pin in the terminal barrels. Tripping means comprising a tapered protrusion (24) is provided on the shutter at its end adjacent the switch for turning off the switch in the turned on position thereof when the plug pin is inserted in the terminal barrels or removed therefrom (Fig 1).