FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CHANGEOVER SWITCH WITH MULTIPLE ACTUATIONS;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention generally relates to changeover switches. More particularly, the invention relates to switches involving multiple actuations.
BACKGROUND OF THE INVENTION
Switches are required for activating or deactivating an electrical connection. In certain application an electrical connection needs to be activated based on deactivation of another electrical connection. In these scenarios the deactivation of one switch and activation of the other switch needs to be accomplished simultaneously. The time between the transition needs to be minimal so that the output is not affected.
Changeover or transfer switches are used in such applications. One practical application of changeover switches lies in a backup system for power generation, in such application the load may receive power from either of two available sources, a main power source and a backup power/ generator source which is used when the main power source is discontinued, providing an interrupted/uninterrupted power to the load.
The design of the changeover switches requires complete electrical isolation of the two power sources. Also, the mechanism used to operate during transition from one source to the other needs to be agile.
Crossover switches are provided in prior art W09824102A11, which discloses switchgear, such as a changeover switch. The switchgear comprises two superposed switching blocks each associated with an actuating block and a control block provided with a control shaft connected to a handle for simultaneously controlling said actuating blocks. This switchgear is

characterized in that the actuating blocks are superposed back to back and are arranged between the mutually inverted switching blocks. The actuating blocks comprise a mechanism with modifiable configuration. Likewise, the connection points between this mechanism and the control shaft can also be modified, thus resulting in five switching combinations between the switching blocks. One of the drawbacks of the prior art switch is that since the switch comprises two superposed switching blocks arranged one above the other, the switch requires more space. Further, the arrangement allows placement of the shaft to be fixed at one side of the arrangement only, i.e. off-centered.
Currently changeover devices with two positions of operation, i.e. center and side is under usage. This functionality is achieved by a four bar type of linkage connecting central and side actuation.
One prior art application 2069/MUM/2006 discloses an existing mechanism for site convertible dual dead center mechanism which involves transfer of motion from driver located at the side to the driven link located at the centre using a floating transfer link with pin joints established with the driver and the driven links.
One drawback with the existing mechanism design is that it can be used for a certain angle of rotation of central gear with limitation of locking beyond that certain degree of rotation as transfer link is used to transfer motion from side to center.
Another drawback associated with the existing mechanism is that the motion transfer efficiency depends on angle between transfer link and driver/driven link hence torque from side is higher than particular torque at center.
Therefore, there is requirement of a mechanism in changeover switch which overcomes the shortcomings associated with the prior arts. SUMMARY OF THE INVENTION
It is an object of the present invention to provide a changeover switch with multiple actuations with similar conditions of angle of rotation and direction of rotation.

The present invention provides a changeover switch with multiple actuations, comprising a top plate and a bottom plate each having slots for guiding top and bottom pins, an actuation mechanism for centre actuation and side actuation, and a rack-pinion arrangement for connecting centre actuation and side actuation.
According to the present invention, an actuation mechanism comprises a top disconnecting means and a bottom disconnecting means, each having toothed pitch wherein the top pin actuates the top disconnecting means and the bottom pin actuates the bottom disconnecting means, an actuating element adapted on a centre shaft, the actuating element has toothed pitch engageable with the toothed pitch of the top disconnecting means and the bottom disconnecting means for multiple actuations and a resilient means for each of the top disconnecting means and bottom disconnecting means to control the movement of the top and bottom pin wherein the movement of the pins beyond a dead center position is manually independent.
According to the present invention, a rack pinion arrangement comprises a center pinion gear mounted on the centre shaft, a side pinion gear mounted on a side shaft off-centrally and a rack having toothed pitch engaging the center pinion gear from one end and the side pinion gear from the other end.
In a related aspect the rack is slanted for reducing the width of the rack-pinion arrangement to accommodate the travel of rack effectively.
In a still further related aspect, the changeover switch of the present invention has an idler adapted between side pinion gear and the rack.
BRIEF DESCRIPTION OF THE DRAWINGS
The features, aspects and other advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in like characters represent like parts throughout the drawings, wherein:

Fig. 1 shows the multi-stage mechanism as per one embodiment of the present invention.
Fig. 2 shows all the components of the mechanism.
Fig. 3 shows the components of first stage of the mechanism as assembled on the bottom
Mechanism Plate.
Fig. 4 shows the components of second stage of the mechanism as stacked between the
separate mechanism plate and top mechanism plate.
Fig. 5 shows the components of first stage and second stage as stacked completely with top
mechanism plate.
Fig. 6 shows the mechanism during OFF condition of the bottom and the top switches as
per one embodiment of the present invention.
Fig. 7 shows the mechanism during dead centre position of transition from OFF to ON condition
or from ON to OFF condition of the top switch as per one embodiment of the present invention.
Fig. 8 shows the mechanism during ON condition of the top switch as per one embodiment of
the present invention.
Fig. 9 shows the mechanism during dead centre position of transition from OFF to ON
condition or from ON to OFF condition of the bottom switch as per one embodiment of the
present invention.
Fig. 10 shows the mechanism during ON condition of the bottom switch as per one embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides changeover switches involving multiple actuations with similar conditions of angle of rotation and direction of rotation. The present invention relates to a site convertible, dual dead center mechanism for changeover switch capable of multiple actuations. The multiple actuations involve center and side actuations.

As per one exemplary embodiment the present invention provides a Rack pinion arrangement for connecting center and side actuation. The rack is connected slant to make the mechanism compact as a straight rack connected directly between center and side increases the width of the mechanism which would be large to accommodate the travel of rack.
As per another embodiment the present invention provides an idler for maintaining the direction of rotation same for center and side operation.
In general, the present invention provides a changeover switch with multiple actuations, comprising a top plate and a bottom plate, each having slots for guiding top and bottom pins, an actuation mechanism for centre actuation and side actuation, having a top disconnecting means and a bottom disconnecting means, each having toothed pitch wherein the top pin actuates the top disconnecting means and the bottom pin actuates the bottom disconnecting means, an actuating element adapted on a centre shaft, the actuating element has toothed pitch engageable with the toothed pitch of the top disconnecting means and the bottom disconnecting means for multiple actuations and a resilient means for each of the top disconnecting means and the bottom disconnecting means to control the movement of the top and bottom pin wherein the movement of the pins beyond a dead center position is manually independent, and a rack-pinion arrangement for connecting centre actuation and side actuation, having a centre pinion gear mounted on the centre shaft, a side pinion gear mounted on a side shaft off-centrally, and a rack having toothed pitch engaging the center pinion gear from one end and the side pinion gear from the other end.
As per one exemplary embodiment, the rack is connected slant. Alternately, the rack can be connected straight within the scope of the present invention. The rack is connected slant to provide a compact mechanism for reducing the width of the rack-pinion arrangement to accommodate the travel of rack effectively.

As per one exemplary embodiment of the present invention an idler may be adapted between side pinion gear and the rack. Alternately, the diameter of the side pinion gear may be larger than the diameter of the centre pinion gear as the idler provides the means for carrying out the movement of the rack effectively.
As per another embodiment of the present invention the centre pinion gear and side pinion gear are disposed on a line substantially on or parallel to the longitudinal axis of the switch.
The resilient means adapted in the changeover switch of the present invention is a compression spring.
Fig. 1 discloses a multi-stage mechanism involving multiple actuations for the changeover switch of the present invention. The first stage (100) discloses the basic mechanism providing actuation of a changeover device. The present invention includes a centre operation (105) and a side operation (205). The second stage (200) discloses the rack pinion arrangement for connecting centre actuation of the centre operation (105) and side actuation of the side operation (205). When in operation, the Pin-top switch (110) actuates top switch disconnecting means (120) and Pin - bottom switch (210) actuates bottom switch disconnecting means (220). On a whole this forms a changeover switch disconnecting means.
Fig. 2 discloses the components of the multi-stage mechanism. The mechanism at first stage (100) involves a central gear (190) having a center operation bearing (192) and a driving element (195), a center actuation shaft (125) and pinion gear arrangement (260a) to be placed in center slot (196) for centre actuation, a slotted gear (130), side operation bearing (160), top pin (180) and bottom pin (182) for actuating top switch and bottom switch, a side actuation shaft (126) and pinion gear arrangement (260) to be placed in side slot (127), spring arm (128) connected with the mechanism from one end and with a spring Rest (170) from the other end, compression spring (140), spacer 1 (155), spacer 2 (160), spacer 3 (165), separate mechanism

plate (250) retaining a rack-pinion arrangement and covering the mechanism from top and a mechanism Plate 3 (150) for retaining the components of the mechanism.
As per one exemplary embodiment the actuation mechanism of the changeover switch of the present invention transfers rotational motion of central gear to translation motion of the top and bottom pin. The changeover switch with multiple actuations involves center actuation and side actuations.
As per another embodiment of the present invention, the mechanism at second stage (200) involves a Rack (240) and a Pinion gear (260) arrangement for side actuation, an Idler (230) for maintaining the direction of rotation same for centre and side operation, a top plate (350) for covering the rack-pinion gear arrangement (240, 260) from top.
The rack pinion gear arrangement is adapted on a separate plate (150) having slots (235, 236) for guiding top and bottom pins.
Fig. 3 shows the bottom mechanism plate (150) retaining all components of first stage (100). The slotted gear (130) on right hand side operates when the central gear (190) rotates in clockwise direction. Similarly, the slotted gear (130) on left hand side rotates when the central gear (190) rotates in anti-clockwise direction. The components are stacked between bottom mechanism plate (150) and separate mechanism plate (250) with the help of spaces (155, 160, 165) and other hardware means. The Fig. 3 also shows a driving element (170) connected to the top switch disconnecting means (120) and the bottom switch disconnecting means (220).
Fig. 4 shows separate mechanism plate 2 (250) retaining the rack-pinion gear arrangement (240, 260) of the second stage (200) of the changeover switch. The components of second stage (200) are stacked between separate mechanism plate (250) and bottom mechanism plate (150) as shown in Fig. 5.
The mechanism may operate in various positions. During the position of the mechanism as shown in fig.6, the switches where the mechanism is attached are in OFF position. The top

pin (180) and bottom pin (182) are each in a position towards the centre gear (190) as shown in fig. 6.
As per one embodiment of the present invention center operation of the mechanism involves center actuation as shown in Fig. 6. For operating the mechanism from OFF to ON condition, the mechanism is rotated in clockwise direction using the center actuation which operates all gears (190, 130, 260) and compresses the spring (140) up to dead center position as shown in Fig. 7. The compressed spring (140) then releases to turn ON the top connected switch (110) with pin as shown in Fig. 8.
For operating the mechanism with ON to OFF condition from the condition as in Fig. 8, the mechanism is rotated in clockwise direction using center actuation which operates all gears (190,130,260) and compresses the spring (140) up to dead center as shown in Fig. 7. The compressed spring (140) then releases to turn OFF the top connected switch (110) with pin as in Fig. 6.
For operating the mechanism with OFF to ON condition from the condition in Fig. 6, the mechanism is rotated in anti-dockwise direction which operates all gears (190,130,260) and compresses spring (140) up to center as shown in Fig. 9. The compressed spring (140) is then released to turn ON the bottom connected switch (210) with pin as shown in FIG. 10.
For operating the mechanism with ON to OFF condition from the condition in Fig. 10, the mechanism is rotated in clockwise direction which operates all gears (190, 130, 260) and compresses the spring (140) up to dead centre as shown in Fig. 9. The compressed spring is then released to turn OFF the bottom connected switch (210) with pin as shown in FIG.8.
The dead center position is reached when the pin-top switch or the pin bottom switch reaches a center position on the slots (335, 336) provided at the top plate and also the slots (135, 136) provided at the bottom plate.
As per another embodiment of the present invention side operation of the mechanism involves side actuation. When the mechanism is actuated from side, the side pinion gear (260a)

drives the idler (230), which in turn drives the connected rack (240). This rack (240) drives the central pinion gear (260b) which is connected to the central gear (190). Again we will be achieving the same set of operations as it is operated from center. Figures 6-10 depicts the same.
Since this being rack-pinion gear arrangement (240, 260) this can be designed for any angle of rotation. This mechanism needs to be stopped by introducing a physical stopping location and not because of any mechanical design limitation. The stopping location is the end of slots (135, 136) for guiding pins in which the top and bottom pin moves.
As per one significant and advantageous aspect, the mechanism of the present invention can work beyond 50 degrees of central gear rotation on either side from OFF condition. Currently designed for 90 degrees and can be extended beyond 90 degree too. Use of Rack pinion arrangement instead of conventional link mechanism, improves the efficiency of the system.
Further, since the mechanism is independent of angle of rotation there is no constraint for total angle of rotation. The mechanism can be designed for any angle of rotation. To remove the locking condition, a Rack-Pinion arrangement is used which provides for a highly efficient motion transfer.
In the forgoing specification, the invention has been described with reference to exemplary embodiment thereof. It will however be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.

WE CLAIM :
1. A changeover switch with multiple actuations, comprising:
a top plate and a bottom plate, each having slots for guiding top and bottom pins; an actuation mechanism for centre actuation and side actuation, having:
a top disconnecting means and a bottom disconnecting means adapted between the top plate and bottom plate, each having toothed pitch wherein the top pin actuates the top disconnecting means and the bottom pin actuates the bottom disconnecting means;
an actuating element adapted on a centre shaft, the actuating element has toothed pitch engageabie with the toothed pitch of the top disconnecting means and the bottom disconnecting means for multiple actuations; and
a resilient means for each of the top disconnecting means and the bottom disconnecting means to control the movement of the top and bottom pin wherein the movement of the pins beyond a dead center position is manually independent; and
a rack-pinion arrangement for connecting centre actuation and side actuation, having a center pinion gear mounted on the centre shaft; a side pinion gear mounted on a side shaft off-centraily; and a rack having toothed pitch engaging the center pinion gear from one end and the side pinion gear from the other end.
2. The changeover switch as claimed in claim 1, wherein the rack pinion arrangement is adapted on a separate plate between the top plate and the bottom plate.
3. The changeover switch as claimed in claim 1, wherein the rack is slanted for reducing the width of the rack-pinion arrangement to accommodate the travel of rack effectively.

4. The changeover switch as claimed in claim 1 or 3, wherein an idler can be adapted between side pinion gear and the rack.
5. The changeover switch as claimed in claim 1, wherein the centre pinion gear and side pinion gear are disposed on a line substantially on or paraliel to the longitudinal axis of the switch.
6. A changeover switch with multiple actuations as claimed in claim 1, wherein the resilient means is a compression spring.
7. A changeover switch with multiple actuations as claimed in claim 1, wherein the changeover switch operation is stopped by end of the slots,