F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention: AN IMPROVED MECHANISM FOR SWITCH DISCONNECTORS

2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(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 THE NVENTION

The present invention relates broadly to switch disconnectors. More particularly, the invention is concerned about an improved an actuating mechanism for use in contact system.

BACKGROUND OF THE INVENTION

In the existing system, the actuating mechanism is an integral part of the contact system i.e., the mechanism is not modular. So that mechanism can’t be isolated from the contact system. If any problem in either contact system or mechanism, to attend it, one has to dismantle the product by disturbing either of them. Also while in assembling phase which will make it more complex to assemble.

External auxiliary switch is used to control wiring [For remote indication of state of the Switch Disconnector (ON/OFF) which it is connected]. This auxiliary switch is connected to the switching device. This increases the dimension of the switching device.

In existing mechanism there is no provision for adding additional poles other than assembled switch and also contact locking arrangements for taking care of short time with stand rating of the switch was not taken care.

Thus, there is a need to overcome the problems of the prior art. Therefore, present inventors have developed an improved mechanism for use in contact system which would be manual independent with contact latching arrangement when the contacts are in closed condition. It would be modular so that it can be separated from the contact system. Within the mechanism dimension, space for auxiliary switch would be provided so that dimension will not increase due to auxiliary switch.
OBJECTS OF THE INVENTION

An object of the present invention is to overcome the problems/disadvantages of the prior art.

Another object of the present invention is to provide an improved mechanism for use in contact system.

Another object of the present invention is to provide an improved mechanism adapted to be manual independent with contact latching arrangement.

Another object of the present invention is to provide an improved mechanism adapted to be modular.

Another object of the present invention is to provide an improved mechanism adapted to provide space for auxiliary switch.

These and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided an improved mechanism for use in contact systems, said mechanism comprising:
a cassette means;
cover means suitably engageable with said cassette means defining an enclosure;
an operating shaft means which runs through the enclosure with a portion of it protruding out of said cover means;
a cam means being rotatably mounted in said cassette means;
a follower means of greater diameter than said cam means;
a spring assembly operatively biased to said cam means;
plurality of link elements operatively engaging said follower means with said cam means and said spring assembly with said cam means;
wherein said cam means comprising plural cam slot profiles having predetermined curvature so as to receive said link elements such that said cam means co-operates with said link elements to convert a rotary input into a linear output;
wherein said cam means further comprises plural dead center slot profiles adapted to receive said link elements engaging said spring assembly with said dead center slot profiles such that said cam means being rotated only after reaching a dead center position.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention there is provided an improved mechanism for use in contact system. When the operator actuates the handle of the Switch Disconnectors, mechanism spring starts storing energy up to the dead centre. After the dead centre (spring over centre) spring releases its stored energy so that the contact system inside the switch disconnector starts changing its state independent of force of the operator. Main focus of this mechanism is to convert the rotary movement to linear movement. Also contact system is held mechanically (latched) so that repulsion force during short circuit condition will not allow it to open the mechanism i.e. contacts are held mechanically. There is also a provision for indication of the mechanism ON/OFF status via an auxiliary contact. In addition to this Auxiliary Contacts for indicating the state of the switch is also incorporated and it is a new cam operated mechanism with contact latching provision which uses less number of components to achieve modular construction

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Other features as well as the advantages of the invention will be clear from the following description.

In the appended drawings:

Figure 1 illustrates a main assembly of switch disconnector.

Figure 2 illustrates an overall view of the mechanism.

Figure 3 illustrates a main assembly of mechanism.

Figure 4 illustrates a cam profile having slots.

Figure 5 illustrates a spring assembly.

Figure 6 illustrates a cam followers and spring assembly in mechanism assembly.

Figure 7 illustrates a view of mechanism in ON position.

Figure 8(a) illustrates a switch in ON position.

Figure 8(b) illustrates a switch in DEAD CENTER position.

Figure 8(c) illustrates a switch in OFF position.

Figure 9 illustrates a mechanism with contact system assembled together and switch in ON position.

Figure 10 illustrates a mechanism with contact system assembled together and switch in OFF position.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and illustrate the best mode presently contemplated for carrying out the invention. Further functioning of the mechanism has been discussed below to describe the way the mechanism operates. However, such description should not be considered as any limitation of scope of the present unit. The 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.

According to a preferred embodiment of the invention, there is provided an improved mechanism for use in contact system. The main embodiment of the present invention comprises of mechanism which drives the contact system for switch disconnectors unit. Figure 1 shows the main assembly of switch disconnector comprising mechanism assembly (2), an auxiliary switch (4) and contact system assembly (3). An operator gives rotary input to the operating shaft (1) which is stored by mechanism springs up to dead centre after which it is released to drive the contact system. So the driving force by the springs ensures that its fully manual independent operation there by increasing the performance of the switch.

Figure 2 shows overall view of the proposed mechanism consist of auxiliary switch (4) and mechanism (2). Whereas mechanism (2) consists of operating shaft (1), provides rotary input by the operator to the mechanism. Follower (7) is connected to the contact system (3) to provide linear movement to the contact system (3).

Figure 3 shows the main assembly of mechanism (2) components consisting of spring assembly (9), cam (10), follower (7), mechanism cassette (11) and its cover (8). Mechanism cassette (11) is the base component in which cam follower is assembled with pin1 (12). So when cam (10) rotates follower (7) follows the cam slot (10a) shown in figure 4 converts rotary input to linear output.

Figure 5 shows spring assembly (9) consist of compression springs and spring guide (9a) with spring pins connected in operating lever (14).

Figure 6 shows spring assembly and cam followers are assembled in mechanism assembly. First cam follower assembled in mechanism cassette (11) with pin 1 (12) , and then spring assembly (9) assembled with cam follower. When operator rotates the operating shaft (1) , spring gets compressed up to dead centre at this case cam (10) will not rotate because of dead centre slot (10b) in cam (10). When spring pins reaches the dead centre slot (10b) i.e. after dead centre cam starts rotating. Pin 2 (13) provided to actuate the auxiliary switch (4) i.e. when cam (10) rotates pin 2 (13) also moves with follower (7) there by operating the auxiliary switch (4) contacts. Here it shows the switch is in off position.

Figure 7 shows the view of the Mechanism in ON position. Here spring assembly (9) and cam follower clearly shows the operating positions. Dead centre slot (10b) is provided to ensure the cam (10) will rotate only after dead centre i.e. when operating lever (14) rotated by operating shaft (1) , springs gets compressed and stores energy. Since spring pins located in dead center slot (10b) in the cam (10) ensures after dead center cam (10) rotates.

Figure 8 shows operating sequence of the mechanism i.e. ON, DEAD CENTER and OFF position of the switch. Figure 8(a) shows the switch in ON position, when operator rotates the operating shaft (1) spring gets compressed and stores energy. Figure 8(b) shows switch in DEAD CENTER position, in this condition spring charged fully and after dead center it releases energy to the CAM assembly. Figure 8(c) shows switch in OFF position.

Figure 9 shows mechanism with contact system (3) assembled together and the switch in ON position. Power supply given or taken out either of the fixed contact1 (5) or fixed contact2 (6).
Moving contacts (15) assembled in Contact Bridge (16) and the same is connected with the cam follower. When mechanism operates the follower (7) moves downward and switch opens. Here repulsion force from contact system (3) under fault condition does not reflect in mechanism (2) because of STW slot (10c) in cam (10). The slot (10c) is made in such a way that force coming from moving contacts will not affect the mechanism when it is in ON condition and in abnormal condition. Figure 10 shows mechanism with contact system (3) assembled together and the switch in OFF position.

ADVANTAGES OF THE INVENTION

1. Modular mechanism for SD.
2. Having space for auxiliary switch without increasing the dimension of SD.
3. Contact latching arrangements provided to ensure short time withstand rating of the switch.
4. Less no of components and ease of assembly.

Glossary
1. Independent manual operation:
It is a stored energy operation where the energy originates from manual power, stored
and released in one continuous operation, such that the speed and force of the operation
are independent of the action of the operator.

2. Dead Centre:
It is the position, where the direction of line of force of action changes. In other words,
up to this position the spring is charged by the operator in one direction. After that the
spring releases the stored energy in the other direction.
3. Auxiliary switch:
It is an external switch used to indicate the state of the Switch Disconnector to remote
centre/ Control room through control wiring. This is actuated by the Switch disconnector
to which it is connected.

Constructional elements
operating shaft (1)
mechanism assembly (2),
contact system assembly (3)
an auxiliary switch (4).
fixed contact1 (5)
fixed contact2 (6)
Follower (7)
mechanism cover (8)
spring assembly (9),
spring guide (9a)
cam (10),
cam slot (10a)
dead centre slot (10b)
STW slot (10c)
mechanism cassette (11)
pin1 (12).
pin 2 (13)
operating lever (14)
Moving contacts (15)
Contact Bridge (16)

WE CLAIM:

1. An improved mechanism for use in contact systems, said mechanism comprising:
a cassette means;
cover means suitably engageable with said cassette means defining an enclosure;
an operating shaft means which runs through the enclosure with a portion of it protruding out of said cover means;
a cam means being rotatably mounted in said cassette means;
a follower means of greater diameter than said cam means;
a spring assembly operatively biased to said cam means;
plurality of link elements operatively engaging said follower means with said cam means and said spring assembly with said cam means;
wherein said cam means comprising plural cam slot profiles having predetermined curvature so as to receive said link elements such that said cam means co-operates with said link elements to convert a rotary input into a linear output;
wherein said cam means further comprises plural dead center slot profiles adapted to receive said link elements engaging said spring assembly with said dead center slot profiles such that said cam means being rotated only after reaching a dead center position.

2. Mechanism as claimed in claim 1 further comprising an auxiliary switch means.

3. Mechanism as claimed in claim 1 wherein said link elements are pins.

4. Mechanism as claimed in claim 1 wherein said spring assembly comprising compression springs and the like.

5. Mechanism as claimed in claim 1 wherein said spring assembly further comprising plurality of spring guide means adapted for mounting of the springs.

6. Mechanism as claimed in claim 1 wherein spring assembly further comprising an operating lever said.

Mechanism as claimed in claim 1 wherein said cam slot profile comprises STW slot

7. An improved mechanism for use in contact systems as herein substantially described and illustrated with the accompanying drawings.