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:
A ROTATORY CAM MECHANISM

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:

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to a cam mechanism for switchgear products and more particularly to a rotary cam mechanism for low voltage switch gear products.

BACKGROUND AND THE PRIOR ART

Presently for switching devices the actuating shaft connected to the vertical rotor actuates the horizontal rotor through an intermediate component and this component is connected to springs. This intermediate component transmits power to the horizontal rotor which in turn, changes the position of the poles. This type of transmission reduces the efficiency of the system, and it requires a heavy spring to obtain a desired performance. This heavy spring induces the stresses in the components and leads to bulkier design.

US 2008/0035464 A1 discloses a switching device which includes a working shaft and a control shaft installed in a frame part, the control shaft being rotatable and adapted to turn the working shaft, and the working shaft being adapted to change the position of poles of the switching device. One of the two shafts passes through the other. The transmission from the control shaft to working shaft is through a cam element which actuates the peg of the working shaft.

The problem in the above described arrangement is that the system becomes inefficient in multiple transmissions i.e. from control shaft to cam element, cam element to working shaft and working shaft to poles of switching device. Another problem is that of coupling of multiple control shafts for a switching device of type I-O-II can reduce the reliability of switching due to multiple linkages.
US 2007/0063796 A1 discloses a modular switching device which includes a plurality of interconnected modules, the modules having a control device module and a pole cell module, the modules of the switching device being interconnected with a shaft adapted to transfer a torque required for operating the switching device from one module to another module. The modular switching device is configured such that each module has a shaft element, and the shaft transferring the torque is composed of directly interconnected shaft elements.
The problem in the above described arrangement is that the coupling with pole cell module and with control device module or mechanism is same, which limits the simplification of mechanism. A simplified mechanism with enhanced coupling that coupled with the pole module provides a better system output.
US 7368676 B2 discloses a switching device having a frame, in which an actuator adapted to rotate a main shaft of the switching device and rotatable around an axis of rotation, the actuator having a 0 position, an I position and a first dead point between the 0 position and the I position, the I position being located by a given angle in a first direction relative to the 0 position. The actuator also has a testing position, the testing position being located by a predetermined angle in a second direction relative to the 0 position, the second direction being opposite relative to the first direction.

The problem in the above described arrangement is that multiple numbers of springs are used and the spring construction is also complex which makes the mechanism complex.
US 6960731 B2 discloses a rotating contact supporting shaft for a low-voltage power circuit breaker, whose particularity consists of the fact that it has a modular structure that comprises, along the rotation axis, at least one first and one second supporting module, each module being functionally coupled to at least one corresponding moving contact of the circuit breaker and being provided respectively with first and second means for connection to at least one first interconnection module; the first interconnection module is interposed between the first and second supporting modules and is provided with third and fourth connection means that are suitable to be coupled respectively to the first and second connection means; the coupling between the first and third connection means and between the second and fourth connection means allows the functional connection between the first and second supporting modules and the direct structural connection of the interconnection module to the first and second supporting modules.

All the given prior arts provide very bulky structure. Also it requires using an additional spring to achieve an idle movement of the mechanism. Thus there is a need to provide a mechanism that would eliminate the use of the extra spring and at the same time provide a simple construction.

The present invention therefore provides a rotary mechanism for use in low voltage switchgear, which would eliminate additional spring and a simpler construction that would increase the efficiency of the mechanism.

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.

Another object of the present invention is to provide a rotary mechanism for use in switches used to toggle between different sources.

Another object of the present invention to provide a single integrated actuating shaft with unique single cam arrangement for switches used to toggle between sources.

Another object of the present invention to provide a single integrated actuating shaft with unique multi-cam arrangement for switches used to toggle between sources.

Another object of the present invention is to cut the single integrated shaft with bevel gears in two half’s across the length to use in a switching device.

Yet another object of the present invention is to provide manual independency in the horizontal rotor by relaxing the rotation of rotor of the contact system till the mechanism nearly achieves the dead center position and then the horizontal rotor drives the rotor of the contact system.

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

SUMMARY OF THE INVENTION

There is provided a rotary cam mechanism for low voltage switch gear products.

Other embodiment of the present invention provides a rotary cam mechanism for low voltage switch gear products comprising a duality of modular mechanism connected back to back by a single integrated actuating shaft; a plurality of spring loaded spring arms attached to said integrated actuating shaft; a plurality of horizontal rotors for coupling said mechanism to a contact shaft; a single cam driving said horizontal rotors thus driving said contact shaft; said cam arranged to accommodate an idle rotation of said integrated actuating shaft during which said horizontal rotor is stationary; said integrated actuating shaft further coupled to a multi-toothed cam that lies on a plane perpendicular to the axis of the vertical rotor; said multi toothed cam element positively coupled to either of the horizontal rotors and a plurality of spring loaded pins a housing for accommodating said rotary cam mechanism.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the appended drawings:

Figure 1 illustrates an overview of single cam mechanism in a switching device from front side.

Figure 2 illustrates an exploded view of concerned mechanism for use in switch dis-connectors and other similar products.

Figure 3 illustrates an initial condition of the switch, where concerned mechanism is in OFF condition.

Figure 4 illustrates the toggle position of the concerned mechanism.

Figure 5 illustrates the final position of the switch, where the concerned mechanism is in ON condition.

Figure 6 illustrates the cam feature of the mechanism.

Figure 7 illustrates an overview of multi-cam mechanism in a switching device from front side.

Figure 8 illustrates an exploded view of concerned mechanism for use in switch dis-connectors and other similar products.

Figure 9 illustrates an initial condition of the switch, where concerned mechanism is in OFF condition.

Figure 10 illustrates the toggle position of the concerned mechanism.

Figure 11 illustrates the final position of the switch, where the concerned mechanism is in ON condition.

Figure 12 shows the multiple stacking of mechanisms for use in applications such as the I-O-II type.

Figure 13 illustrates an integrated actuating shaft arrangement for the above application.

Figure 14 illustrates the backside of contact system housing which is capable of mating with the front side of mechanism.

Figure 15 illustrates the front side of contact system housing which is capable of mating with the backside of mechanism.

Figure 16 illustrates the various coupling positions between mechanism and contact system on the front side.

Figure 17 illustrates the various coupling positions between the mechanism and contact system on the backside.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.

Reference is first invited to Fig 1 where the single cam mechanism in a switching device from front side is shown. Figure 2 to 6 represents functioning and description of Single Cam Mechanism.

Figure 7 to 11 represent functioning and description of Multi Cam Mechanism.

Figure 12 to 15 represent functioning and description of coupling arrangement.

The invented system is thus a single cam mechanism in a switching device from front side.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly in the present invention provides a rotary mechanism for use in low voltage switchgear, which would eliminate additional spring and a simpler construction to increase the efficiency of the mechanism. It provides:
1. Single Cam Mechanism &
2. Multi Cam Mechanism

The Single Cam mechanism demonstrates an alternative means to achieve the functions of the prior art. The Multi Cam mechanism demonstrates a simplified means to improve upon the efficiency of the prior art.

These simpler rotary mechanisms with a unique coupling arrangement of pole assembly provide the following features and advantages.
a. One pole Couples with another pole with positive locking.
b. Side 1 of pole assembly couples with side 1 of mechanism and Side 2 of pole assembly couples with side 2 of mechanism to provide an idle motion to certain angle of rotation and positive drive for remaining angle of rotation to mechanism.

For a switching device of type I-O-II, the present invention provides a single integrated vertical rotor / actuating shaft which eliminate multiple linkages.
CONSTRUCTIONAL COMPONENTS:
Single CAM mechanism as shown in Fig. 2 comprises:
1. Vertical Rotor (Actuating shaft)
2. Horizontal Rotor
3. Common Housing (Bottom)
4. Metal Spring Rest
5. Metal Stopper
6. Common Housing (Top)
7. Spring Arm Screw
8. Mechanism Spring
9. Spring Arm Holder
10. Stacking Nut
11. Stacking Screw

The Multi CAM mechanism as shown in Figure 8 comprises:
1. Vertical Rotor (Actuating Shaft)
2. Vertical Rotor Base
3. Common Housing (Front)
4. Front Horizontal Rotor
5. Driver Cam
6. Driven Cam
7. Back Horizontal Rotor
8. Spring Arm
9. Mechanism Spring
10. Fixed Spring Rest
11. Common Housing (Back)
12. Moving Spring Rest

Operation of Single Cam Mechanism:

According to a preferred embodiment of the invention, there is provided a rotary mechanism for use in switches. The mechanism comprises of two modular mechanism connected back to back by a single integrated actuating shaft. Single mechanism used for switch device of type I-O and multiple stacks are used for toggle switches of type I-O-II.

The single integrated actuating shaft with cams when cut in the middle across the length is used as a single mechanism. The mechanism in its assembled condition is shown in Figure 1. The mechanism comprises of a vertical rotor (1) placed on the bottom housing (3) that is capable of rotating about its central axis. Attached to this vertical rotor are spring loaded spring arms (7, 9). The vertical rotor functions as the actuating shaft. On either side of the vertical rotor are horizontal rotors (2) that are used to couple the mechanism with the contact system. The horizontal rotors are driven with the help of a single cam. The cam is designed to accommodate an idle rotation of the vertical rotor during which the horizontal rotor is stationary. It is after this idle rotation that the horizontal rotor is positively driven by the vertical rotor. The cam arrangement is designed in such a way that both horizontal rotors rotate in the same sense. This is true for both operations of the switch i.e. ON to OFF and OFF to ON.

Figure 2 shows the exploded view of the above mechanism. When the vertical rotor functioning as the actuating shaft is rotated clockwise, the sequence of operation is as shown in the following figures.

Figure 3 shows the initial condition of the mechanism i.e. the OFF position of the switch. The vertical rotor must now be rotated in the direction of the arrow. Figure 4 shows the position of the mechanism in its toggle position when actuating shaft is rotated clockwise. Until a little after this position, the horizontal rotors remain stationary. Figure 5 shows the mechanism in its final condition i.e. ON position of the switch. The function of the mechanism is the same when the direction of rotation is reversed from its ON position.

Figure 6 illustrates the cam feature of the mechanism. The cam feature (a) on the vertical rotor (1) is located on one side and feature (b) is located on the other. The feature (c) is located on the horizontal rotor (2). The feature (c) is made to mesh with feature (a) on one side and feature (b) on the other. The uniqueness of this arrangement is that a single variety of horizontal rotor (2) can be used on either side (front and back) by just rotating the component 180° about the horizontal plane and 180° about the vertical plane. The cam is so designed as to rotate both horizontal rotors in the same sense and with equal velocity and angular position which is essential for switching operation.

Advantages:
1. Only one variety of spring used. This results in a less complicated design.
2. Two separate horizontal rotors of the same variety are used instead of a single bulky component resulting in material saving and better space utilization.
3. Housing is used as the stopper which reduces the complexity of the design.
4. Both top and bottom housings are of the same variety reducing cost.

Operation of Multi Cam Mechanism:

According to a preferred embodiment of the invention, there is provided a rotary mechanism for use in switches of the dis-connector type. The mechanism in its assembled condition is shown in Figure 7. The mechanism comprises of a vertical rotor (1) which performs the function of an actuating shaft. This vertical rotor is positively coupled to a multi-toothed cam (5) which lies on a plane perpendicular to the axis of the vertical rotor. A similar cam element is mounted on a cage like structure through which the vertical rotor is passed. The cage consists of the following components: a front horizontal rotor (4), a back horizontal rotor (7), a multi toothed cam element (6) that may be positively coupled to either of the horizontal rotors and spring loaded pins which function as a moving spring rest (12). The contact shaft of the switch may be connected to either or both of the horizontal rotors. The angles of rotation of the cage depend upon the shape and size of the cam elements and can be adjusted. When the vertical rotor is rotated by some external means the cage is also made to rotate due to the meshing of the cam elements. As a result both horizontal rotors rotate thus rotating the contact shaft of the switch. Figure 8 shows the exploded view of the concerned mechanism.

When the vertical rotor is rotated clockwise, the operation of the mechanism can be described as follows. Figure 9 shows the mechanism in its initial condition i.e. OFF condition of the switch. Figure 10 shows the mechanism in its toggle position when the vertical rotor is turned clockwise from its initial position. Figure 11 shows the mechanism in its final position i.e. ON position of the switch. The function of the mechanism is the same when the direction of rotation is reversed from its ON position.

For applications such as the I-O-II type, multiple type mechanism can be stacked to achieve the desired functions. This is illustrated in Figure 12. In order to achieve this integral shaft as shown in Figure 13 may be used. The single integrated actuating shaft with cams when cut in the middle across the length can be used in a single mechanism.

Advantages:
1. Use of a multi toothed cam results in higher efficiency than that of a single cam.
2. The springs being directly coupled to the driven shaft increases the efficiency of the mechanism. This results into safer design as required spring force becomes much less.
3. Only one variety of spring is used which reduces the complexity of the mechanism.
4. Arranging the spring in a vertical plane results in optimum space utilization.

Coupling:
Figure 16 shows the coupling of the front horizontal rotor of the mechanism with that of the back end of the contact shaft. The back end of the contact shaft is shown in Figure 15. The three positions are namely OFF, DEADCENTRE, and ON. The mechanism coupler is identified by the hatching lines. It is clear from the figure that the mechanism coupler does not drive the contact shaft throughout its rotation but only through a part of it. It is also clear that the contact shaft rotates after the DEADCENTRE position.

Figure 17 shows the coupling of the back horizontal rotor of the mechanism with that of the front end of the contact shaft. The front end of the contact shaft is as shown in Figure 14. The three positions are namely OFF, DEADCENTRE, and ON. The mechanism coupler is identified by the hatching lines. It is clear from the figure that the mechanism coupler does not drive the contact shaft throughout its rotation but only through a part of it. It is also clear that the contact shaft rotates after the DEADCENTRE position. Thus the same effect is achieved from either end of the mechanism.
Advantages:
1. Profile which provides positive single stage coupling as well as two stage coupling.
2. Two stage coupling provides manual independency as well as positive drive after certain angular rotation.
3. Reduces number of varieties; hence less number of components, manufacturing cost and investment.
4. A guide is provided in the form of central protruded taper portion so as to facilitate assembly process. Thus reducing assembly time and effort.
5. Eliminates the need of providing manual independency at mechanism level, reducing complexity at mechanism level. This eliminates additional components in mechanism and transmits torque directly from vertical actuating shaft to horizontal rotor. And also by transmitting energy of the spring directly to the horizontal rotor increases the efficiency, and thus reduces the spring force required. This reduces the stresses in the components and increases reliability.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.
We claim:

1. A rotary cam mechanism for low voltage switch gear products comprising:
a housing;
a duality of modular mechanism connected back to back by a single integrated actuating shaft;
a plurality of spring loaded spring arms attached to said integrated actuating shaft;
a plurality of horizontal rotors for coupling said mechanism to a contact shaft;
a single cam driving said horizontal rotors thus driving said contact shaft; wherein said cam being arranged to accommodate an idle rotation of said integrated actuating shaft during which said horizontal rotor is stationary; said integrated actuating shaft further coupled to a multi-toothed cam that lies on a plane substantially perpendicular to the axis of the vertical rotor; said multi toothed cam element positively coupled to either of the horizontal rotors and
a plurality of spring loaded pins.
2. Rotary cam mechanism as claimed in claim 1, wherein said integrated actuating shaft is a vertical rotor capable of rotating about its central axis.

3. Rotary cam mechanism as claimed in claim 1 wherein said cam is configured to rotate said horizontal rotors to achieve switching operation.

4. Rotary cam mechanism as claimed in claim 1 wherein said housing is adapted to be used as a stopper.

5. Rotary cam mechanism as claimed in claim 1 wherein said single rotary cam mechanism is used for switch device of type I-O.

6. Rotary cam mechanism as claimed in claim 1 wherein multiple said rotary cam mechanism is stacked together to be used for toggle switches if type I-O-II.

7. A rotary cam mechanism for low voltage switch gear products as herein described and illustrated with reference to the accompanying drawings.