DESC:TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to Moulded Case Circuit Breakers (MCCB), andmore particularly, to a rotary mechanism for the operating contact system, which is intrinsic with the MCCB.

BACKGROUND AND THE PRIOR ART

Circuit Breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions it will make the circuit closed, carry current for a specified time and breaks the circuit under specified abnormal circuit conditions.

Moulded Case Circuit Breakers (MCCB) are employed for current interruption. More particularly MCCBs are utilized to protect instruments from damage during adverse conditions prevailing during the operation of the circuit in which moulded case circuit breaker is employed. During adverse conditions like short circuit, the current rises to an alarmingly high level. This high current may cause damage to the parts (loads)in the electrical system. Hence during these conditions the circuit has to be opened to protect the parts (loads)which are connected after the breaker.
A circuit breaker can be manually opened and closed, as well as automatically opened to protect conductors or equipment from damage caused by excessive heating due to over current in abnormal conditions such as overload or short-circuit.

The mechanism of the circuit breaker plays a vital role in determining the credibility of the breaker. A good mechanism should ensure quick and manually independent opening and closing of contact system.

Five operations are to be performed by the MCCB mechanism. They are ON, OFF, RESET, TRIP and TRIP FREE. The first three operations are initiated by operator. Whereas the remaining are triggered by the trip signal given by the release which senses the abnormal conditions and gives TRIP command to the mechanism, so that the latter opens the circuit.

Conventionally the ON, OFF and RESET operations are done with the linear operation of the knob. In the existing technology, we have to add an external linear to rotary converting mechanism to be used, when fitted to panel boards and position the rotary knob in the place where the axis of the fork and axis of the rotary knob intersects. In the existing technology, it is difficult to reposition the rotary knob based on any requirements and the profile of the gear teeth will become critical.

US 6518526 B2 discloses a handle-operating mechanism for a circuit breaker includes a rotary operating handle for opening and closing a main-circuit contact of a circuit breaker, a rotating gear operably connected to the operating handle and having a first engaging device, and a contact opening-and-closing mechanism having a toggle gear meshing with the rotating gear. A clutch gear is connected to the operating handle to be interposed between the operating handle and the rotating gear, and has a second engaging device. An idle stroke is formed such that when the circuit breaker is turned on, the operating handle runs idly after rotation of the operating handle has been started and before the second engaging device engages the first engaging device to drive the rotating gear for actuating the toggle gear. The prior-art document provides a contact opening-and-closing mechanism being linked to the operating handle through the rotating gear and the toggle gear. The person skilled in the art will be able to understand that the rotating gear is used to operate the mechanism can be placed only in the line passing through the axis of the toggle gear only, and the teeth profile of rotating gear is a combination of bevel gear and spur gear. Further, the engagement between the rotating gear and toggle gear is feeble. Furthermore, the manufacturing of the rotating gear is a complex process.

Therefore, the present invention overcomes the disadvantages prevailing in the conventional arts and provides a rotary mechanism for operating contact system in circuit breakers, therefore the parts of the circuit breaker can be modified easily as the requirement change.

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 the operating contact system, which is intrinsic with the MCCB.

Another object of the present invention is to provide a rotary knob used for operating the mechanism can be placed anywhere as intended.

Another object of the present invention is to provide an easy to manufacture and less costly mechanism.

Yet another object of the present invention is to provide a contact opening-and-closing mechanism being linked to the operating handle (rotary knob) through the Rotary Knob Gear, Slider Gear, and Fork Gear.

Yet another object of the present invention is to provide a rotary knob used to operate the mechanism, which may be placed anywhere as intended.

Yet another object of the present invention is toprovide the full engagement all operating points as all the gears have spur gear profile.

Still another object of the present invention is to provide simplicity as the manufacturing of all the gears is simple.

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

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

In an aspect of the present invention, there is provided a mechanism for operating the contact system in circuit breaker, said mechanism comprising: a fork attached to a mounting plate(s); a fork gear connected to said fork by means of a slot arrangement; a slider gear; a rotary knob gear having a profile protruding outwardly to said circuit breaker for inserting a rotary knob; a rotary knob gear holder with plurality of profiles for connecting said slider gear through one of said profile and said rotary knob through other said profile; therefore rotating said rotary knob facilitate rotation of said rotary knob gear which slides said slider gear along said profile of said rotary knob gear holder, consecutively rotates said fork to facilitate rotary mechanism for operating the contact system in said circuit breaker.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF 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.

Figure 1 illustrates the isometric views of conventional mechanism.

Figure 2illustrates the isometric views of intrinsic rotary operated mechanism.

Figure 3 illustrates the exploded view of mechanism.

Figure 4 illustrates the intrinsic rotary operated mechanism in ON CONDITION.

Figure 5 illustrates the intrinsic rotary operated mechanism in OFF CONDITION.

Figure6 illustrates the intrinsic rotary operated mechanism in TRIP CONDITION.

Figure 7 illustrates the rotary knob gear.

Figure8 illustrates the slider gear.

Figure9 illustrates the fork gear.

Figure10 illustrates the rotary knob gear holder.

Figure11 illustrates the cross sectional view of mechanism.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.

Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
Accordingly, present invention provides a rotary mechanism for the operating contact system, which is intrinsic with the MCCB.

The present invention has a Fork Gear 17 as shown in Figure 9 attached to the Fork 6, which is mounted on the Mounting Plates 1. And the Fork Gear 17 is made to rotate towards the axis of the Fork 6 with the help of the profile A of the Slider Gear 21 as shown in Figure 8 mounted to slide on the profile A of Rotary Knob Gear Holder 18 as shown in Figure 10. And the Rotary Knob Gear 19 as shown in Figure 7 is mounted to the profile B of Rotary Knob Gear Holder 18and is clamped with the help of the Rotary Knob Gear Clamp 20.
The profile A of the Rotary Knob Gear 19 will be protruding out of the breaker through which the Rotary Knob 24 will be inserted and screwed. The user provides input through the Rotary knob 24, which in turn rotates the Fork 6 mobilizing the mechanism to the desired position.

The other components which form the mechanism are somewhat conventional and the description about those is as mentioned below:
The Upper Links 3, Lower Links 5 and Main Springs 23 are placed in their respective positions in the spring pin 22 and the assembly is riveted to each side of the Latch Link2 as shown in Figure 11. And the Latch Link assembly is hinged to the Mounting Plates 1 with the help of Latch Link Pin 10. Similarly, the Latch Bracket 7 is hinged to the Mounting Plates 1 with the help of the Latch Bracket Pin 8 and the Trip Plate 14 is hinged along with the Trip Biasing Spring 15 to the Mounting Plates 1 with the help of the Trip Plate Pin 13.

The rollable Reset Pin 16 is assembled with the Latch Link 2 which is used to reset the mechanism back to the OFF position as indicated in Figure 5andto stop the Fork 6 in the trip position.

The Main Springs 23provide the force required to operate the breaker and is mounted to the Spring Pin 22 andFork 6 with the help of the Fork Spring Pin 9.

The operator has access to the mechanism through the Rotary Knob 24 which will be projected outwards from the housing of the breaker. The Rotary Knob 24 is placed above the fork 6 of the operating mechanism. In MCCBs, breaker will feature three positions in the top cover near the rotary knob to show ON, OFF and TRIP conditions.

When the rotary knob indicates ON it means the breaker is in ON condition i.e., the current path is closed. Similarly the position of the rotary knob indicates the current state of the circuit breaker.

According to standards, the vertical position of the rotary knob aligning towards the line side i.e., 900 from the X+ direction considering the breaker is mounted horizontally or vertically and the viewer is seeing the breaker from the load side, should be marked as ON POSITION. And the rotary knob is rotated 900 in the counter-clockwise direction to reach the OFF POSITION. The rotary knob will be somewhere between these two positions to indicate the TRIP POSITION.

As said before, TRIP command is given automatically to the contacts by the release if it senses an abnormal condition like overload and short circuit. If the trip signal is given, the breaker opens the circuit and the rotary knob goes to the trip position to show the operator that a fault has occurred in the system.

If the operator wants to switch ON the breaker after the breaker is tripped, he/she cannot do it without resetting the breaker. This is to make sure that the operator shouldn't switch ON the breaker before clearing the fault.

Resetting of the breaker is done by rotating the rotary knob (fork) towards the OFF position from the TRIP position. This movement loads the mechanism spring and latches the latch link and now it is possible for the operator to switch ON the breaker. All these mechanisms are called semi-automatic mechanisms since for ON and OFF operation, the rotary knob of the breaker has to be taken from their respective ON or OFF positions to a position called dead center beyond which the mechanism becomes independent of the operator and completes the respective action automatically.

ON position: The Rotary Knob 24 will be indicating ON position as shown in Figure 4. In this position, the Fork 6 will be in the position far away from the trip systemand the Upper Links 3, Lower Links 5 will be holding the contacts in the closed circuit condition with the help of the Drive Shaft Pin 25.

OFF/RESET position: The Rotary Knob 24 will be indicating OFF position as shown in Figure 5.In this position, the Fork 6 will be in the position very near to the trip system the Upper Links 3, Lower Links 5will be holding the contacts in the open circuit condition with the help of the Drive Shaft Pin 25. And RESET position can be witnessed only when trying to reset the breaker from the TRIP position and when the Rotary Knob 24 is left free, it will be resting in the OFF position.

TRIP position: The Rotary Knob 24 will be indicating TRIP position as shown in Figure 6.In this position, the Fork6 will be in the position defined between the ON and OFF positions and the position is constrained by the rotation of Latch Link 2. The Reset pin 16 stops the Latch Link 2 from further rotation. And the contacts will be in the opened condition.

The present invention used to convert the required rotary motion of the fork from conventional linear to rotary is newand simple and the new components are listed in the next level.

The user operates the Rotary Knob 24 based on his/her intention to close/open the circuit or the load connected. When the Rotary Knob 24 is operated, the Rotary Knob 24 in turn rotates the Rotary Knob Gear 19 and this in turn slides the Slider Gear 21 along the profile A provided in the Rotary Knob Gear Holder 18. The Slider Gear 21 in turn rotates the Fork Gear 17, which operates the conventional mechanism of the breaker.

Since the positions and profiles of each component are constrained by different parameters of the design, the designer needs to achieve the desired result by modifying only those which will not contribute directly to the functional parameters.

In the case of our “Variable positionable intrinsic rotary operated mechanism”, we can achieve the desired result by changing the PCDsand the profiles of the Fork Gear 17as shown in Figure 9and Rotary Knob Gearas shown in Figure 7, based on the positions in which they need to be placed. Similarly, the Slider Gear 21’s position as well as profile can be changed and adopted to the design intent as shown in Figure 8

ADVANTAGES:
· The Rotary Knob Gear connected to Rotary Knob is made to slide the Slider Gear, which in turn rotates the Fork Gear which is mounted to the fork.
· Since, the Rotary Knob Gear slides the Slider Gear, it can be positioned anywhere along the vertical axis just by redesigning the tooth profiles.
· The Rotary Knob Gear can be placed anywhere. And can be achieved by altering the tooth profile of the Rotary Knob Gear and the teeth profile of side A of the Slider Gear.
· Since all the gears have spur gear profile, the profile of the gear teeth has become easy to manufacture.
· Eliminate the requirement of the linear to rotary converting mechanisms in panel boards, and the breaker can be operated directly with a rotary handle.
· Eliminate the complex profiles which may be needed to operate the breaker with an intrinsic rotary mechanism. .
· Place the rotary mechanism anywhere as decided unlike other rotary mechanisms
· The design of the profiles of the parts can be modified easily as the requirement change.
,CLAIMS:1. A mechanism for operating the contact system in circuit breaker, said mechanism comprising:
a fork attached to a mounting plate(s);
a fork gear connected to said fork by means of a slot arrangement;
a slider gear;
a rotary knob gear having a profile protruding outwardly to said circuit breaker for inserting a rotary knob;
a rotary knob gear holder with plurality of profiles for connecting said slider gear through one of said profile and said rotary knob through other said profile;
therefore rotating said rotary knob facilitate rotation of said rotary knob gear which slides said slider gear along said profile of said rotary knob gear holder, consecutively rotates said fork to facilitate rotary mechanism for operating the contact system in said circuit breaker.

2. The mechanism as claimed in claim 1, wherein a main spring providing a force for operating said circuit breaker is connected to said fork using a fork spring pin.

3. The mechanism as claimed in claim 1, wherein said slider gear comprises a profile for facilitating rotation of said fork gear toward the axis of said fork, therefore rotating said fork.

4. The mechanism as claimed in claim 1, wherein said rotary knob is operated manually for operating the contact system during ON and OFF condition of said circuit breaker.

5. The mechanism as claimed in claim 1, wherein said rotary knob gear clamps to rotary knob gear holder through said profile using a rotary knob gear clamp.

6. The mechanism as claimed in claim 1, wherein a rollable reset pin is assembled with the latch link to facilitate resetting the mechanism of said circuit breaker to off position, therefore stopping said fork in trip position.

7. The mechanism as claimed in claim 1, wherein said rotary knob gear, said slider gear are spur gear(s).

8. The mechanism as claimed in claim 1 further comprising a feature indicating positions of said rotary knob in ON, OFF and TRIP conditions of said circuit breaker.

9. The mechanism as claimed in claim 1, wherein said circuit breaker is reset by rotating said rotary knob towards the OFF position from the TRIP position, thereby switched ON said circuit breaker.