Claims:WE CLAIM:
1. A kinematic linkage mechanism for operating a vacuum interrupter of a vacuum circuit breaker, the mechanism comprising:
a rod extending between a first end and a second end, a laterally extending pin press fitted into a hole provided on the first end of the rod, the second end of the rod is coupled to a moveable contact of the vacuum interrupter;
a tube extending between a first end and a second end and coupled to an operating mechanism of the vacuum circuit breaker at the first end, the tube having a first washer fixedly mounted on the second end and a second washer slideably mounted on tube, a pair of opposite oblong slots provided on the surface of the tube and a pin resting on the oblong slots thereby allowing movement of the rod inside the tube, at least some portion of the rod extending outwardly of the second end of the tube; and
a partially compressed coil spring adapted between the first washer and the second washer, the spring force of the coil spring forces the second washer to rest against the pin;
wherein when the vacuum circuit breaker is moved to a closed position the tube is pulled thereby moving the kinematic linkage mechanism towards the direction of the pull, the mechanism moves until the moveable contact comes in contact with a fixed contact of the vacuum interrupter and thereafter the tube moves away from the second the end of the rod thereby further compressing the coil spring if any further pulling force is applied on the tube at the first end and till the remaining travel on operating mechanism side is exhausted.

2. The kinematic linkage mechanism as claimed in 1, wherein at least some portion of the rod is threaded adjacent to the second end of the rod and a pair of nuts are mounted on the threaded portion, the amount of partial compression on the spring is adjusted using the pair of nuts.

3. The kinematic linkage mechanism as claimed in claim 1, wherein the tube is coupled to the operating mechanism using an input lever having an input end and an output end, the input end is connected to the operating mechanism and the output end is connected to the first end of the tube, the input lever rotates in a clockwise direction on a fulcrum thereby pulling the tube when the vacuum circuit breaker is moved to the closed position.

4. The kinematic linkage mechanism as claimed in claim 1, wherein the rod is coupled to the moveable contact of the vacuum interrupter using an output lever having an input end and an output end, the input end is mounted on the rod adjacent to the second end and the output end is connected with the moving contact of the vacuum interrupter, wherein the output lever moves the moveable contact towards the fixed contact of the vacuum interrupter until the moveable contact is in contact with the fixed contact and thereafter any further movement of the input lever is used to further compress the coil spring.

5. The mechanism as claimed in claim 3, wherein the input lever is a bell crank.

6. The mechanism as claimed in claim 4, wherein the output lever is a bell crank.

7. The mechanism as claimed in claim 1, wherein the first washer is welded to the tube.
, Description:FIELD OF THE INVENTION
[001] The invention relates a kinematic linkage mechanism for operating a vacuum circuit breaker.

BACKGROUND OF THE INVENTION
[002] A vacuum circuit breaker is a kind of circuit breaker where arc quenching takes place in vacuum medium and is commonly used in medium voltage power distribution systems. Vacuum circuit breaker generally comprises of vacuum interrupter, an operating mechanism and a kinematic linkage provided between the operating mechanism and the vacuum interrupter. The vacuum interrupter further comprises of a fixed contact/electrode, a moveable contact/electrode and an arc shield mounted inside a vacuum chamber. The vacuum circuit breaker is configured to be operated between a closed position and an open position. In open position, the moving contact/electrode is separated from the fixed contact and in closed position the moving contact/electrode is in contact with the fixed contact/electrode thereby completing the electrical circuit and allowing the current to pass through the vacuum circuit breaker.
[003] In operation, when the vacuum circuit breaker is moved to an open position, on separation of electrodes inside the vacuum chamber, an arc is generated between the electrodes/ contacts which is required to be quenched. As the vacuum chamber is maintained at vacuum, the separation of contacts/ electrodes causes the release of vapor filled in the contact space which consists of electrons and positive ions liberated from contact/electrode material. Consequently the arc start extinguishing as the metallic vapours, electrons an ions produced during the arc begin to re-condense on the surface of the contacts/electrodes thereby resulting in regain of dielectric strength of the vacuum.
[004] Whereas when the vacuum circuit breaker is moved to a closed position either manually or remotely, a contact loading spring which is coupled to the kinematic linkage generates a push which eventually forces the moveable electrode/ contact to touch/make fixed contact with/separate from the fixed contract as the moveable contact is connected with the spring operating mechanism through the linkage.
[005] However, as the compression spring in the kinematic linkage, which is responsible for providing the required contact load/ push, is mounted vertically on the rod, the overall size of the vacuum circuit breaker increases which is undesirable. Further, due to such vertical arrangement of the compression spring, the reduction of size of the vacuum circuit breaker is also not possible. Moreover, in push kind of force transfer, proper alignment of the spring axis with respect to input and output levers has to be assured.
[006] Therefore, there exists a need for a kinematic linkage mechanism for operating the vacuum interrupter of the vacuum circuit breaker which addresses at least the abovementioned problems.

SUMMARY OF THE INVENTION
[007] In an embodiment, in one aspect the invention provides a kinematic linkage mechanism for operating a vacuum interrupter of a vacuum circuit breaker, the linkage mechanism comprising a rod extending between a first end and a second end, a laterally extending pin press fitted into a hole provided on the first end of the rod, the second end of the rod is coupled to a moveable contact of the vacuum interrupter, a tube extending between a first end and a second end and coupled to an operating mechanism of the vacuum circuit breaker at the first end, the tube having a first washer fixedly mounted on the second end and a second washer slideably mounted on tube, a pair of opposite oblong slots provided on the surface of the tube and the pin is resting on the oblong slots thereby allowing movement of the rod inside the tube, at least some portion of the rod is extending outwardly of the second end of the tube, and a partially compressed coil spring adapted between the first washer and the second washer, the spring force of the coil spring forces the second washer to rest against the pin, wherein when the vacuum circuit breaker is moved to a closed position the tube is pulled thereby moving the operating mechanism towards the direction of the pull, the operating mechanism moves until the moveable contact comes in contact with a fixed contact of the vacuum interrupter and thereafter the tube moves away from the second end of the rod thereby further compressing the coil spring if any further pulling force is applied on the tube at the first end and till the remaining travel on operating mechanism side is exhausted.
[008] In an embodiment of the present invention, at least some portion of the rod is threaded adjacent to the second end of the rod and a pair of nuts is mounted on the threaded portion, the amount of partial compression on the spring is adjusted using the pair of nuts.
[009] In another embodiment of the present invention, the tube is coupled to the operating mechanism using an input lever having an input end and an output end, the input end is connected to the operating mechanism and the output end is connected to the first end of the tube, the input lever rotates in a clockwise direction on a fulcrum thereby pulling the tube when the vacuum circuit breaker is moved to the closed position.
[010] In a further embodiment of the present invention, the rod is coupled to the moveable contact of the vacuum interrupter using an output lever having an input end and an output end, the input end is mounted on the rod adjacent to the second end and the output end is connected with the moving contact of the vacuum interrupter, wherein the output lever moves the moveable contact towards the fixed contact of the vacuum interrupter until the moveable contact is in contact with the fixed contact and thereafter any further movement of the input lever is used to further compress the coil spring.
[011] Yet in another embodiment of the present invention, the input lever is a bell crank and the output lever is a bell crank.
[012] In some embodiments of the present invention, the first washer is welded to the tube.

BRIEF DESCRIPTION OF THE DRAWINGS
[013] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows a kinematic linkage mechanism for operating a vacuum interrupter of a vacuum circuit breaker in accordance with an embodiment of the invention.
Figure 2 shows a kinematic linkage mechanism for operating a vacuum interrupter of a vacuum circuit breaker in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[014] The present invention is directed towards a kinematic linkage mechanism for operating a vacuum interrupter of a vacuum circuit breaker. In this regard, the invention provides a kinematic linkage mechanism which can be mounted horizontally inside a vacuum circuit breaker thereby decreasing the overall size of the vacuum circuit breaker.
[015] Figure 1 through 2 shows a mechanism 100 for operating a vacuum interrupter of a vacuum circuit breaker in accordance with an embodiment of the present invention. As shown, the mechanism comprising a tube 100, a rod 200 adapted inside the tube, a partially compressed spring 300 mounted on the tube and a pin 400 provided on the rod.
[016] The tube extends between a first end 110 and a second end 120 and a pair of opposite oblong slots (not shown) is provided on the surface of the tube. A pair of washers is also mounted on the tube. In this regard, a first washer 510 is fixedly mounted on the second end of the tube and a second washer 520 is slideably mounted on the tube thereby allowing the second washer to slide on the surface of the tube. In an embodiment, the first washer is welded to the second end of the tube.
[017] The rod extends between a first end 210 and a second end 220. A hole (not shown) is provided adjacent to the first end of the rod and a pin is press fitted into the hole where the pin is extending laterally through the hole on both sides. The rod is adapted inside the tube in such a manner that the pin rests on the oblong slots provided on the tube and the rod can move along the length of the oblong slots thereby providing a relative motion between the rod and the tube. As shown, at least some portion of the rod is extending outwardly of the second end of the tube. In an embodiment, at least some portion of the rod which is extending outwardly of the second end of the tube is threaded and a pair of nuts 600 is mounted on the threaded portion.
[018] A partially compressed coil spring is adapted between the first washer and the second washer. In this regard, the spring is fixed at its both the ends to the respective washers. In an exemplary embodiment, spring is partially compressed by firstly placing the spring between the first and second washers and thereafter pulling the tube and the rod away from each other. As the second washer can slide over the surface of the tube and the second washer is resting on the pin, the motion pin inside the oblong slot compresses the spring. Thereafter, once the desired compression of the spring is achieved, the pair of nuts are bolted to the threaded portion. In this regard, the nuts prevent any relative motion between the rod and the tube and prevent any recoiling of the spring to its original portion. Further, the compression of the spring can also be adjusted by tightening/loosening the nuts over the threaded portion as per requirement.
[019] In an embodiment, the mechanism as described hereinabove is adapted in a vacuum contact breaker. The first end of the tube is coupled to an operating mechanism of the vacuum circuit breaker and the second end of the rod is coupled to a moveable contact of the vacuum interrupter. In an exemplary embodiment, the mechanism is coupled to the operating mechanism of the vacuum circuit breaker by using an input lever 700 and the second end of the rod is coupled to the moveable contact of the vacuum interrupter by using an output lever 800.
[020] The input lever has an input end 710 and an output end 720. As shown, output end of the input lever is connected to the first end of the tube and the input end of the input lever is connected to the operating mechanism. In an embodiment, the input lever is a bell crank. In operation, input lever rotates in a clockwise direction on a fulcrum when the vacuum circuit breaker is moved to a closed position. As the output end of the input lever is connected to the first end of the tube, the tube is pulled in by the lever.
[021] The output lever has an input end 810 and an output end 820. As shown, the input end is mounted on the rod adjacent to the second end and the output end is connected with the moving contact of the vacuum interrupter. When the tube is pulled, the whole mechanism is pulled towards the input lever thereby rotating the output lever on the fulcrum 830 and the output end of the output lever moves the moveable contact towards the fixed contact of the vacuum interrupter. In this regard, the output lever moves the moveable contact towards the fixed contact of the vacuum interrupter until the moveable contact is in contact with the fixed contact and thereafter any further movement of the input lever is used to further compress the coil spring. In this regard, when the moveable contact is in contact with the fixed contact, any further pulling of the tube by the input lever forces the second end of the tube to move away from the second end of the rod thereby generating a relative movement between the rod and the tube. Such movement of the second end of the tube compresses the spring as the spring is fixed at both ends on the first and the second washer respectively and the second washer is not moving (as it is resting against the pin which acts as a stopper for the movement if the second washer towards the first end of the tube).
[022] Advantageously, the kinematic linkage mechanism can be mounted horizontally inside the vacuum circuit breaker therefore the overall size of the vacuum circuit breaker can be considerable reduced. Due to pulling action on the spring assembly the force component is efficiently getting transferred as the spring gets aligned properly when it is pulled between input and output levers and guided on tube surface. The components of the kinematic linkage become more compact but still maintain required constraint motion to transfer the motion as well as force onto the moving contact of the vacuum circuit breaker.
[023] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.