DESC:TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to moulded case circuit breaker (MCCB) with the modularity in components and connections involved in the architecture of the breaker. More particularly, the present invention provides an improved mechanism-rotor shaft assembly for molded case circuit breaker.

BACKGROUND OF THE INVENTION

A circuit breaker is a mechanical device capable of making, breaking and carrying normal currents and making and breaking currents under specified abnormal circuit conditions such as that of a short circuit or overload. Circuit breakers are employed in the electrical system or network for switching and protection of electrical equipments. During adverse conditions like short circuit, the current shoots up to an alarmingly high value, this can pose grave threat to the electrical system. It can cause damage to the equipments and loads installed downstream in the system. The circuit breaker clears the fault rapidly so as to minimize the damage caused by thermal and mechanical stresses to downstream equipments.

In molded case circuit breaker the arc quenching and fault clearing process takes place inside the housing. The molded case circuit breaker consists of contacts system, mechanism, currents sensing unit. The contact system of the circuit breaker consists of fixed contacts and moving contacts. During ON condition of the circuit breaker, a set of springs provide the contact force to maintain the moving contact in ON condition. The current conducts from the first fixed contact onto the moving contact and then onto the second fixed contact. The fixed contacts are designed in such a way that the during short circuit conditions, an electromagnetic force develops between the moving contacts and fixed contacts. The electromagnetic force results in a clockwise torque on the moving contact. Meanwhile there is an anti clockwise torque provided by the springs acting on the contacts. The electromagnetic torque acts against the spring torque and enable the moving contact to open up and thus clear the fault.

The moving contact with the spring arrangement is assembled inside a rotating chamber called shaft. Different arrangements of springs and shaft configurations are currently employed for maintaining contact pressure. Arc chute assemblies, made up of deion plates neatly stacked up together are used for pulling, lengthening and quenching of electric arc during fault interruption. Perforated metal sheet or mesh is used sometimes, so as to de-ionize and cool the hot ionized gases. In some breakers, perforated plastic sheet is used as an alternative.

Operating mechanism of the circuit breaker enables manually independent opening and closing of the contact system in ON, OFF, Trip and Reset condition. The trip unit senses the current flowing through the contact system, and under pre-specified abnormal conditions gives the command signal for the operating mechanism of the breaker to trip i.e., break the circuit. The trip unit used are generally either thermo-magnetic or electronic (microprocessor based) trip unit.

The various termination units/modules cater to the various types of termination like direct link, box clamp, rear, tunnel as per the customer requirements at the endpoint use. In the circuit breakers, pins are provided as joining means for creating pivot axis. For high volume processes and especially in automation of mechanism-roto shaft assembly without pins are recommended. Pins however are a quintessential part of assembly, as they provide an easy way of creating pivot axes and always take time to assemble in circuit breaker. The existing pin type assembly in circuit breaker is tiresome and therefore improvements are required to reduce assembly time to eliminate tedious process. The pin linkages in mechanism-roto shaft assembly adding time and cost to final product and also reducing the production rate. Using pin linkages increasing the total number of components in assembly, in manner to reduce complexity and time improvements are required so that pins can be eliminated and no extra component is required to assemble mechanism-rotor shaft assembly.

Some prior art documents given here for reference:
US 6377144 disclosed the base and mid-cover configuration for circuit breaker enclosures. The design provides a separate top cover, mid cover and base wherein the mid-cover wall height to base wall ratio is such that the stresses imparted upon the base side walls when pressures are exerted, for example, by gaseous discharge are withstood.

US 7116194 disclosed an electric pole for a low-voltage power circuit breaker, comprising an insulating enclosure that has a lower wall, an upper wall, two side walls, a rear wall and a front wall, at least one arc chute, at least one fixed contact and at least one moving contact that can be mutually coupled/uncoupled, and a first electric terminal and a second electric terminal that are functionally associated with the fixed contact and the moving contact and allow electrical connection of the pole in input and in output, its particularity consisting of the fact that the insulating enclosure comprises a first half-shell and a second half-shell which are mutually coupled along corresponding coupling surfaces and form a self-supporting structure, the first and second half-shells being shaped so as to form at least one compartment that is suitable to accommodate the fixed contact and the moving contact and the arc chute, and second and third containment volumes, which are arranged on mutually opposite sides with respect to the compartment and are suitable to accommodate respectively the first and second electric terminals.

US 5298874 disclosed a modular low voltage multi-pole circuit breaker, including a plurality of identical single-pole breaking units each including a parallelipipedic insulating box having two opposite parallel large side faces and two opposite parallel small side faces, two terminals located at respective opposite parallel small side faces, a stationary contact electrically connected to one of the terminals, a movable contact co-operable between a first position contacting the stationary contact and a second position separated from the stationary contact and a molded case for housing the single-pole breaking units. The molded case has two opposite parallel side walls having the same thickness, the single-pole breaking units being sequentially arranged and parallel to each other and parallel to the side walls such that adjacent single-pole breaking units are spaced apart a distance equal to twice the thickness of the side walls, the single-pole breaking units being spaced apart at a constant pitch. An operating mechanism is provided to be common to all single-pole breaking units for simultaneously operating all single-pole breaking units.

US 6933814 disclosed a molded case, cassette type circuit breaker for a multi-pole electrical distribution circuit includes a number of cassettes equal to the number of poles in the multi-pole electrical distribution circuit and a pin disposed through each cassette. The pin is formed from a dielectric material. The pin may be further disposed through a portion of an operating mechanism for aligning the cassettes and the operating mechanism. Each cassette may include a rotor, a pair of electrical contacts, and a contact arm supported in the cassette by the rotor. In this embodiment, the pin may be a cross pin that extends between each rotor. The dielectric material may include phenolic, melamine, silicone, epoxy, polyester, fiberglass and the like. Alternatively, the pin includes a steel bar coated with the dielectric material, where the dielectric material may include, for example, epoxy, silicon, Teflon, and the like. A pair of end caps may be disposed over end surfaces of the rotor. Pole spacing between adjacent cassettes may be about one inch or less while providing sufficient dielectric integrity to meet requirements of the UL 489 standard.

Thus, in view of above mentioned and other existing drawbacks, there exists a need to provide an efficient, cost effective and easy operable mechanism to create an assembly of linkages which avoids the use of pins in the assembly. Further, this mechanism must also improve the performance of existing or newly proposed MCCB’s.

OBJECTS OF THE INVENTION

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

Another object of the present invention is to provide an improved rotor shaft contact assembly for molded case circuit breaker.

Another object of the present invention is to provide a robust modular design of subassembly mechanical assembly and rotor shaft assembly for circuit breaker.

Yet another object of the present invention is to provide an efficient, cost effective and easy operable mechanism to create an assembly of linkages which avoids the use of pins in the assembly.
Yet another object of the present invention is to create a combination of flared Height from component itself and groves in the mating member creating an instantaneous pivot axis for revolute coupling by using current improved manufacturing process.

Yet another object of the present invention is to provide an ease of assembly by avoiding additional fastening processes and providing a base for piling up the subsequent components in the assembly.

Yet another object of the present invention is to provide a flared height which is pin shaped and made from component itself can be consider as a permanent joint so it has more strength compare to riveted pins and risk of failure is less compare to riveted means.

Yet another object of the present invention is to provide an ease of assembly that can help in automation for assembling the mechanism parts and reduces time and cost of final product and also better productivity can be achieved.

Still another object of the present invention is to reduce the number of components for the circuit breaker assembly thereby reducing the overall cost and the compactness of the MCCB’s.

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 PRESENT INVENTION

In an aspect of the present invention, there is provided a circuit breaker assembly comprising:
a housing;
a contact system secured within said housing, said contact system comprises at least a fixed contact and at least a moving contact;
a drive shaft assembly secured within said housing, said drive shaft assembly comprises a rotor shaft having a slot and a stopper;
an operating mechanism assembly secured within said housing, said operating mechanism assembly comprises a lower link and a upper link; wherein said lower link having at least two legs with plurality of protrusions thereon forming a protruding surface at the end of said legs; wherein said drive shaft assembly operatively connected to said operating mechanism assembly by inserting said protrusions on said lower link in said slot provided on said rotor shaft of said circuit breaker therefore reducing the failure of said circuit breaker in ON, OFF, TRIP and RESET operational conditions.

In another aspect of the present invention, there is provided, a circuit breaker assembly having an operating mechanism assembly (6) and a rotor shaft (R1). The operating mechanism assembly (6) may include at least two pin shaped protrusions (71, 72) on at least one lower link assembly (7). The rotor shaft (R1) may include at least two slots (R11, R12). The at least two pin shaped protrusions (71, 72) are adapted to fit in said at least one slot (R11) on said rotor shaft (R1) thereby forming a revolute joint and a mechanism-rotor shaft assembly.

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 perspective view of breaker, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates the perspective view of mechanism-rotor shaft mounted with housing, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates the stand alone mechanism assembly with all components, in accordance with an embodiment of the present subject matter.
Figure 4 illustrates the rotor shaft construction for mechanism mounting, in accordance with an embodiment of the present subject matter.

Figure 5 illustrates the shows the exploded view assembly sequence, in accordance with an embodiment of the present subject matter.

Figure 6 illustrates the mechanism rotor shaft assembly, in accordance with an embodiment of the present subject matter.

Figure 7 illustrates the lower link position during on–off operation, in accordance with an embodiment of the present subject matter.

Figure 8 illustrates the lower link position during trip condition in accordance with an embodiment of the present subject matter.

Figure 9 illustrates the breaker assembly in the on condition, in accordance with an embodiment of the present subject matter.

Figure.10 illustrates the breaker assembly in the off condition, in accordance with an embodiment of the present subject matter.

Figure 11 illustrates the cross section of the mechanism rotor shaft assembly in accordance with an embodiment of the present subject matter.

Figure 12 illustrates the lower link assembly, in accordance with an embodiment of the present subject matter.

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 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 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, in one embodiment the present invention provides an improved mechanism-rotor shaft assembly for molded case circuit breaker. A modular assembly of mechanism-rotor shaft assembly is provided. The mechanism assembly (6) may be assembled with rotor shaft R1 assembly without pins as shown in figure 2. The figure 1 shows the isometric view of complete breaker.

In one embodiment, the operating mechanism assembly comprises a lower link (7) with circular protrusions through which the mechanism assembly attached to the rotor shaft (R1) of the driveshaft assembly and eliminates the use of pin for the assembling, shown in figure 3. The circular protrusions on the lower link act as a pin joint between mechanism assembly and rotor shaft assembly. The rotor shaft R1 of the driveshaft assembly having a slot R11 and a stopper R12 which maintains the linkages with the lower link 7 and ensure final position of rotor shaft with the lower link during ON-OFF operation.

In one embodiment, the lower link assembly attached to rotor shaft assembly by inserting the protrusions (71, 72) on lower link into R11 slot in rotor shaft R1. After insertion of lower link into rotor shaft, rotate the lower link until protrusion (73, 74) touch surface R12 so that lower link get its final position automatically and both axes of R12 and 71, 72 come in one line. The R12 on the rotor shaft interact with small protrusions 73 and 74 provided on lower link to stops the lower link assembly 7 in position with rotor shaft so that lower link does not come out from the rotor shaft assembly, during ON, OFF, Trip and Reset condition of the circuit breaker. The rotor shaft assembly with lower link assembly is shown in figure 4. This modular assembly reduces the time required for assembly and provides ease of assembly, reduces extra components and cost of overall breaker. The figure 6 shows the mechanism-rotor shaft assembly after both assembled together. The figure 7 and figure 8 shows lower link assembly position during normal ON-OFF operation and trip operation

Various parts of the present assembly as disclosed in the invention are as given below:
1. Housing
2. Cover
3. Top cover
4. Knob
5. PTT
6. Operating mechanism Assembly
7. Lower link
71, 72 for mechanism connection with rotor shaft
73, 74 to ensure lower link assembly cannot come out while ON-OFF
8. Upper link
M1 Moving Contact
F1 Fixed contact
R1 Rotor Shaft
R11 slot for lower link assembly for mechanism-rotor shaft
R12 Ensures stopper for lower link to come out of slot during ON-OFF

In one embodiment, the present invention provides a pin shaped circular protrusion on the lower link assembly 71, 72 which is part of mechanical assembly is inserted into the slot R11 provided in the rotor shaft and joined together. The mechanism assembly connected with rotor shaft, when contact system of the circuit is in ON condition only. In case, the contact system is in Trip condition, reset the mechanism standalone and switch it into ON condition. After reset the lower link (7) is in a particular position automatically through which the mechanism assembly assembled with rotor shaft. After assembling mechanism assembly with rotor shaft, the mechanism assembly has to rotate until lower link 73, 74 stops in rotor shaft through the stopper (R12) so that during ON, OFF, TRIP lower link cannot come out of slot R11. This modular construction provides ease of assembly saves time, cost and reduces the failure of the assembly. During normal operation 73, 74 are in touch with R12 slots on rotor shaft. This ensures final position of Rotor shaft contact assembly during on condition

In one embodiment, the present invention provides a modular type assembly having two modules, i.e. one is mechanism assembly and other is rotor shaft assembly. The operational conditions like ON, OFF, TRIP for mechanism assembly is checked standalone before assembling to rotor shaft. This pre checking of mechanism assembly reduces the overall failure of breaker provides interchangeability of modules as well.

In one embodiment, the present invention provides an improved linkage assembly without pins and extra hardware’s for assembling mechanism-rotor shaft assembly. This eliminates the tiresome process of insertion of pins in hole by alignment two holes of rotating components. The mechanism is directly connected to rotor shaft assembly by lower link means so that elimination of pin gives benefit to achieve final position of rotor. Because in this, for joining two assemblies no extra pins is required so that no extra tolerance and clearance of pins will add in this type of assembly.

In one embodiment, a circuit breaker assembly having an operating mechanism assembly (6) and a rotor shaft (R1) is disclosed. The operating mechanism assembly (6) may include at least two pin shaped protrusions (71, 72) on at least one lower link assembly (7). The rotor shaft (R1) may include at least two slots (R11, R12). The at least two pin shaped protrusions (71, 72) are adapted to fit in said at least one slot (R11) on said rotor shaft (R1) thereby forming a revolute joint and a mechanism-rotor shaft assembly.

In one embodiment an axis of said at least one slot (R11) and an axis of said at least two pin shaped protrusions (71, 72) act as a common axis and coupled together.

In one embodiment, said at least two pin shaped protrusions (71, 72) are adapted to fit in said at least one slot (R11) on said rotor shaft (R1) in ‘ON’ operating condition.

In one embodiment, when operating mechanism assembly (6) in trip condition resets said operating mechanism assembly (6) to switch it in ‘ON’ operating condition, said lower link assembly (7) is in a particular position and thereby automatically assembles itself with said rotor shaft (R1).

In one embodiment , said mechanism-rotor shaft assembly rotates so as to couple said at least two pin shaped protrusions (71, 72) with said slot (R12) on said rotor shaft (R1) thereby restricting said mechanism-rotor shaft assembly to break during ‘ON’, ‘OFF’, ‘TRIP’, and ‘RESET’ operating conditions.

In one embodiment, a circuit breaker assembly is disclosed. The circuit breaker assembly comprises of a housing; a contact system secured within said housing, said contact system comprises at least a fixed contact and at least a moving contact; a drive shaft assembly secured within said housing, said drive shaft assembly comprises a rotor shaft having a slot and a stopper; an operating mechanism assembly secured within said housing, said operating mechanism assembly comprises a lower link and a upper link.

In one embodiment, said lower link having at least two legs with plurality of protrusions thereon forming a protruding surface at the end of said legs.

In one embodiment, said drive shaft assembly operatively connected to the operating mechanism assembly by inserting said protrusions on said lower link in said slot provided on said rotor shaft of said circuit breaker therefore reducing the failure of said circuit breaker in ON, OFF, TRIP and RESET operational conditions.

In one embodiment said drive shaft assembly connected to the operating mechanism assembly during ON condition of said contact system.

In one embodiment, said lower link after insertion to an extent, thereby said protruding surface on said lower link attached to said stopper for maintaining said lower link in a closed position with said rotor shaft, during ON and OFF operational condition of said contact system.
Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include:
· The current invention is a robust modular design of subassembly mechanical assembly and rotor shaft assembly for final assembly (mechanism-rotor shaft assembly). The current invention defines a way to create an assembly of linkages which avoids the use of pins. This is done by creating a combination of flared height from component itself and groves in the mating member creating an instantaneous pivot axis for revolute coupling by using current improved manufacturing process.
· This eliminates the use of spins in this process. The current invention providing an ease of assembly by avoiding additional fastening processes and providing a base for piling up the subsequent components in the assembly.
· This eliminates the use of hardware for assembly. Ease of assembly can help in automation for assembling the mechanism parts and reduces time and cost of final product and also better productivity can be achieved.
· Better ergonomic considerations
· Less no. components results less friction between two rolling parts
· Elimination of pins eliminates the tiresome process of assembly of pin.

Although embodiments for compatible mechanism–rotor shaft contact assembly have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features are disclosed as examples of implementations for compatible mechanism–rotor shaft contact assembly.
,CLAIMS:1. A circuit breaker assembly comprising:
a housing;
a contact system secured within said housing, said contact system comprises at least a fixed contact and at least a moving contact;
a drive shaft assembly secured within said housing, said drive shaft assembly comprises a rotor shaft(R1) having at least two slots (R11, R12);
an operating mechanism assembly secured within said housing, said operating mechanism assembly comprises a lower links (7) and a upper links; wherein said lower link (7) having at least two legs with plurality of protrusions (71, 72)thereon forming at least two protruding surface (73, 74) at the end of said legs;
wherein said drive shaft assembly operatively connected to said operating mechanism assembly by inserting said protrusions (71, 72) on said lower link (7) in said slot provided on said rotor shaft of said circuit breaker therefore reducing the failure of said circuit breaker in ON, OFF, TRIP and RESET operational conditions.
2. The circuit breaker assembly as claimed in claim 1, wherein said drive shaft assembly is connected to operating mechanism assembly during ON condition of said contact system.
3. The circuit breaker assembly as claimed in claims 1 and 2, wherein rotating said lower link after insertion to an extent, thereby said protruding surface (73, 74) on said lower link (7) attached to said slot (R12) for maintaining said lower link (7) in a closed position with said rotor shaft (R1), during ON and OFF operational condition of said contact system.
4. A circuit breaker assembly having an operating mechanism assembly (6) and a rotor shaft (R1) characterized in that
said operating mechanism assembly (6) comprising at least two pin shaped protrusions (71, 72) on at least one lower link assembly (7); and
said rotor shaft (R1) comprising at least two slot (R11, R12), wherein
said at least two pin shaped protrusions (71, 72) are adapted to fit in said at least one slot (R11) on said rotor shaft (R1) thereby forming a revolute joint and a mechanism-rotor shaft assembly.
5. The circuit breaker assembly as claimed in claim 4 wherein an axis of said at least one slot (R11) and an axis of said at least two pin shaped protrusions (71, 72) act as a common axis and coupled together.
6. The circuit breaker assembly as claimed in claims 4 and 5, wherein said at least two pin shaped protrusions (71, 72) are adapted to fit in said at least one slot (R11) on said rotor shaft (R1) in ‘ON’ operating condition.
7. The circuit breaker assembly as claimed in claims 4 to 6, wherein when operating mechanism assembly (6) in trip condition resets said operating mechanism assembly (6) to switch it in ‘ON’ operating condition, said lower link assembly (7) is in a particular position and thereby automatically assembles itself with said rotor shaft (R1).
8. The circuit breaker assembly as claimed in claims 4 to 6, wherein said mechanism-rotor shaft assembly rotates so as to couple said at least two pin shaped protrusions (71, 72) with said slot (R12) on said rotor shaft (R1) thereby restricting said mechanism-rotor shaft assembly to break during ‘ON’, ‘OFF’, ‘TRIP’, and ‘RESET’ operating conditions.