COMPLY AFTER PROVISIONAL
LEFT ON „ Q 01 fflOb
FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention.- A SINGLE MECHANISM TO OPERATE MULTIPLE
SWITCHES WITH MECHANICAL INTERLOCKING
2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY: Indian
(c) ADDRESS : L& T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
The present invention relates to a mechanical interlocking mechanism for electrical switches. More particularly, the invention relates to a mechanical interlocking mechanism which is compact thereby reducing the overall mechanism volume and weight making it cost effective and adapted for fast electrical isolation where two or more switches are operating. This mechanism can be used at places where isolation of two or more switches is necessary, more specifically in transfer switch or changeover switch.
BACKGROUND AND PRIOR ART
Many times customers have a backup system for power generation, which is used when the main power source is discontinued, so that, the critical operations will continue by the help of backup power source, like generator or inverter. Thus there is need to have a device which will have two power supplies i.e. main power supply and backup power supply at input side of the switch and one output power supply for the load, further these input power supplies must have complete electrical isolation from each other, and only one power supply should get connected to a load at a time.
Thus there is a need to have special switch to attain all the aforesaid requirements, such type of switch is commonly known as CHANGEOVER OR TRANSFER SWITCH, this type of switch is able to obtain perfect isolation between two input power supplies and only one power supply gets connected to a load at a time.
US 20030034693 discloses mechanical interlock, achieved by sandwiching the interlock device into power switches, wherein the mechanical interlocking device is designed in such a way
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that only one switch can have ON condition, the mechanism so developed have two L shaped tabs, which are connected to the interconnected members of the both the switches, further alternative arrangement described in this invention wherein the mechanical interlock, includes a U shaped Bracket having its ends secured to the bodies of both power switches, the locking actuator is a rocking bar pivotally connected to the walls of the U-shaped bracket through a central pivot and the ends of the rocking bar are in contact with respective actuator pin.
In operation, the rocking bar ensures that both actuator pins never extended to the ON state simultaneously. In case the first actuator pin is already extended in the ON state, the second actuator pin shall push the first actuator pin to the OFF state when second actuator pin is switched to the ON state. Additionally, both actuator pins can simultaneously retract to the OFF state.
US 20040118667 discloses an elongated interlock member, having a longitudinal axis at first and second ends. At least one fastener structure is disposed on the elongated interlock member, for enabling slidable connection of the elongated interlock member to a switch panel. A switch handle-receiving contour is disposed at each of the first and second ends of the elongated interlock member. A switch handle engagement surface is disposed within each switch handle-receiving contour. The switch interlock apparatus further comprises guide structure, operable associated with the at least one fastener structure, for constraining the slidable movement of the elongated interlock member to linear reciprocating movement.
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In the interlocking assemblies discussed above, the interlocking is achieved by juxtaposition of two switches which includes their individual mechanisms as well as separate interlock apparatus connected to them. In none of the above documents a single interlocking mechanism operating two or more switches with the same interlock apparatus have been found.
Thus there is a need to provide a mechanical interlocking mechanism, which is compact with reduced overall mechanism volume and weight making it cost effective adapted for fast electrical isolation where two or more switches are operating.
The present inventors have found that the interlocking mechanism designed in desired manner comprising components arranged and integrated in a way that amounts to compactness and simplicity of the overall interlocking mechanism volume thereby reducing the weight and results in fast interlocking.
OBJECTS OF INVENTION
Thus one object of the present invention is to provide complete mechanical interlocking and electrical isolation between the two switches.
Another object is to provide single and compact mechanism for operating two switches.
Yet another object is simple design and ease of assembly.
Another object of the present invention is to provide cost reduction due to compaction provided in the interlocking mechanism.
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SUMMARY OF INVENTION
Thus according to one aspect of the present invention there is provided an interlocking mechanism comprising :
atleast a plate provided with plurality of holes and slots and joined to each other so as to form partial enclosure, said holes receiving driving means comprising shaft wherein at a predetermined distance of the shaft is provided a cam means ergonomically designed secured in bracket means;
said cam means being co-operatively engaged to plurality of roller means in housings provided with protrusions passing through spring means and supporting means whereby the spring means are supported on walls of the supporting means;
plurality of gear means provided on the shaft being operatively engaged with plurality of slotted gear means comprising predetermined slots so as to accommodate another set of roller means being journalled to pin means,
wherein one end of the pin means rest in the slots of the base plates in a manner to move in the slots so as to operate switches,
said gears being adapted to provide compact and simple interlocking facilitating meshing and separation of gears.
DETAILED DESCRIPTION OF INVENTION
In the present invention the mechanical interlocking mechanism comprises main driving means mounted on base plates where all
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the other components of the mechanism are also located. The base plates comprises of holes so as to accommodate the main driving means which comprises square shaped shaft (hereinafter referred to as operating shaft), which bears and supports most of the essential components of the interlocking mechanism.
The operating shaft is assembled with specially profiled cam which is located rigidly on the shaft such that the contacting surface of the operating shaft passing through the cam is so engaged to the cam that the angular movements / rotations of the operating shaft cause angular movements / rotations of the cam in turn actuating both rollers to move in transverse direction. The said rollers are accommodated in a holding means comprising of protrusions (herein also described as arm) ending at one end to form U-shaped housing provided with holes through which pin means supporting the rollers can pass. The U-shaped housing also supports as one of the resting walls for spring means. The pins are press fitted into the holes of the U-shaped housing and guides the rollers in their transverse movement allowing free rotation of the rollers about the axis of the pins. The arms of the holding means communicates between plurality of spring means and the cam through arm supports which are fixed in a predetermined manner to the base plates. The spring means comprises plurality of main springs of equal specifications operatively connected to arm means, which are adapted to locate the said springs. The springs travel a predetermined length of the arms. The said arms are placed in the guiding bracket assembled on the operating shaft and guided by the arm supports fastened on the base plate by means of bushes, which are press fitted in the arm supports. These arm supports also act as resting walls against which the main springs are rested.
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The rollers are located on the pin passing through the shaped housing such that the periphery of the cam operatively engages with the rollers during its rotation. The cam comprises of angular apex pointing radially outward such that the maximum radius in contact with the rollers generate maximum compression of the spring and slight over rotation of the cam provides re-expansion of the springs. The angular movements/ rotations of the cam causes the springs to compress till the apex of the cam profile. The potential energy stored in the springs due to compression is released during the expansion and utilized to operate the switch rapidly.
The operating shaft comprises plurality of gear means wherein top driving gear set and bottom driving gear set comprise driving gear and driving gear with missing tooth rigidly mounted on top and bottom side of the operating shaft. The mechanism also comprises two more set of gears (top slotted gear set and bottom slotted gear set) comprising driven slotted gear and driven slotted gear with missing tooth, mounted back to back on pin means located in slots provided on the base plates. The said pins are journalled to rollers which are placed in the slots of the driven slotted gears with missing tooth such that the rotational movement of the slotted gears are transformed into linear motion of the pins which start moving in the slots of the base plates so as to operate the switches. Driving gears with missing tooth have the same profile as that of driving gear but one tooth less than that of the driving gear. The driven slotted gear with missing tooth have the same profile as slotted gear but have one tooth less than slotted gear. As the operating shaft is rotated in clockwise direction the said top slotted gear set gets
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completely coupled and bottom slotted gear set is completely decoupled with operating shaft causing mechanical interlocking.
In the OFF condition both top and bottom sided set of driven slotted gear and driven slotted gear with missing tooth are in coupled condition with the operating shaft through the set of top and bottom sided driving gear and driving gear with missing tooth.
If the switch is operated from OFF condition to ON condition, depending on the source of power supply required, wherein either set of driven slotted gear and driven slotted gear with missing tooth gets completely coupled with the operating shaft as they remain in the meshed condition with the said set of driving gear and driving gear with missing tooth. Further the other set of said driven slotted gear and driven slotted gear with missing tooth is completely decoupled from the operating shaft as they are no more in meshed condition with the set of said driving gear and driving gear with missing tooth.
The aforesaid driver gear with missing tooth and driven Slotted gear with missing tooth is provided herein to facilitate mechanical interlocking, by ease of meshing and separation of the gears in operation.
In OFF state to avoid the free play of the said top and bottom set of slotted gear a torsion spring is used which is located in between the spring locator and set of slotted gear.
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BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates an isometric view of the mechanical interlocking mechanism of the present invention.
Figure 2 illustrates an exploded view of the interlocking mechanism of the present invention.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates the interlocking mechanism comprising base plates (17) where the two plates (17) are joined with each other by means of plurality of spacers (18) which hold the plates (17). The base plates (17) comprises holes (22) (also shown in figure 2) to accommodate operating shaft (1) and predetermined rectangular slots (23) (also shown in figure 2) for accommodating pins (16) (also shown in figure 2) which are on the other end journalled to the rollers (15) placed in the slots (24) (also shown in figure 2) of the slotted gears (11, 12) .
Figure 2 illustrates exploded view of the interlocking mechanism comprising operating shaft (1) is assembled with specially profiled cam (2) rigidly supported on the operating shaft (1). Main springs (3) are operatively connected to arm means (4) adapted to locate the said springs (3). The arms (4) are placed in the guiding bracket (8) assembled on the operating shaft (1) and guided by plurality of arm supports (7) fastened on the base plate (17) by means of bushes (21) press fitted in the arm supports (7). Pins (5) are press fitted in the housings (25) comprising protrusion/arms (4) guiding the rollers (6) in free rotation. The operating shaft
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(1) comprises plurality of gear means wherein top and bottom driving gear set of driving gear (9) and driving gear with missing tooth (10) are rigidly mounted back to back on top and bottom side of the cam (2) . Top slotted gear set and bottom slotted gear set of driven slotted gear (11) and driven slotted gear with missing tooth (12), mounted back to back on the said base plate (17). Spring locator (13) operatively connected to arm (4) via pin (5) guides slotted gear (11) and driven slotted gear with missing tooth (12) . Torsion spring
(14) is located on the driven slotted gear (11), driven slotted gear with missing tooth (12) and spring locator (13) . Spacer (18) is used to hold two base plates (17). Spacer (19) is sandwiched between guiding bracket (8) and Driving gear
(9) . Bush (20) is the one which is used to locate operating shaft (1) and base plate (17) . Bush (21) gives the guide to arm (4) in arm support (7).The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its true spirit. The invention is not limited to the details cited above. For example the housings, gears and cam does not restricts scope of the invention. The improved structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements which will still be comprised within its true spirit.
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WE CLAIM
1. An interlocking mechanism comprising :
atleast a plate provided with plurality of holes and slots and joined to each other so as to form partial enclosure, said holes receiving driving means comprising shaft wherein at a predetermined distance of the shaft is provided a cam means ergonomically designed secured in bracket means;
said cam means being co-operatively engaged to plurality of roller means in housings provided with protrusions passing through spring means and supporting means whereby the spring means are supported on walls of the supporting means;
plurality of gear means provided on the shaft being operatively engaged with plurality of slotted gear means comprising predetermined slots so as to accommodate another set of roller means being journalled to pin means,
wherein one end of the pin means rest in the slots of the base plates in a manner to move in the slots so as to operate switches,
said gears being adapted to provide compact and simple interlocking facilitating meshing and separation of gears.
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2. An interlocking mechanism as claimed in claim 1, the cam means comprises angular apex pointing radially outward such that the maximum radius in contact with the rollers generate maximum compressions of the spring means thereby storing potential energy and slight over rotation of the cam provides re-expansion of the spring means thereby releasing the stored energy.
3. An interlocking mechanism as claimed in claims 1 and 2, wherein the housing comprising rollers engaged to the cam being provided with plurality of predetermined holes so as to hold pins to bear the rollers.
4. An interlocking mechanism as claimed in claim 1, wherein the gear means comprises plurality of driving gears and driving gears with missing teeth.
5. An interlocking mechanism as claimed in claim 1, wherein the gear means further comprises of driven slotted gears and driven slotted gears with missing teeth.
6. An interlocking mechanism as claimed in claim 4, wherein the driving gear with missing teeth comprises one tooth less than the driving gear.
7. An interlocking mechanism as claimed in claim 5, wherein the driven slotted gear with missing teeth comprises one tooth less than the driven slotted gear.
8. An interlocking mechanism as claimed in claim 1, wherein the slotted gears comprise ergonomical profiled slots so as to guide pins bearing rollers such that the rotational
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movement of the slotted gears gets transformed into linear motion of the pins in the slots of the base plates thereby operating the switches.
9. An interlocking mechanism substantially as herein described and illustrated with reference to the accompanying figures.
Dated this 28th day of June 2006,
Sonali Bhokarikar OF S. MAJUMDAR & CO (Applicant's Agent)
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ABSTRACT
TITLE : A SINGLE MECHANISM TO OPERATE MULTIPLE SWITCHES WITH MECHANICAL INTERLOCKING
The present invention relates to an interlocking mechanism comprising atleast a plate (17) provided with plurality of holes (22) and slots (23), said holes (22) receiving driving means comprising shaft (1) wherein at a predetermined distance of the shaft (1) is provided a cam means (2) which is cooperatively engaged to plurality of roller means (6) in housings (25) provided with protrusions (4) passing through spring means (3) and supporting means (7). The mechanism comprises plurality of gear means (9, 10) provided on the shaft (1) being operatively engaged with plurality of slotted gear means (11, 12) so as to accommodate another set of roller means (15) being journalled to pin means (16) to provide compact and simple interlocking facilitating meshing and separation of gears (9, 10, 11, 12).
Figure 1