DESC:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to a circuit breaker and more particularly to an assembly to actuate charging and closing latch mechanism in the circuit breakers.

BACKGROUND

[002] A circuit breaker is a commonly used in an electrical switching device designed to connect, carry, disconnect and protect the equipment connected in the electrical circuit from damage caused by overload, under-voltage or short circuit etc. The operating mechanism of a circuit breaker having a moving contact and a stationary contact is switched ON (closed) or OFF (tripped) by using energy stored in a spring charged mechanism. When the circuit breaker is charged, the rotating cam element in the charging circuit drives a component to either extend or compress springs in order to store potential energy. This energy is stored with the help of a closing latch on a close shaft.

[003] When circuit breaker mechanism is switched ON, rotation of close shaft takes place, releasing closing latch and spring energy output is given to a mechanism linkages in order to close the circuit breaker. The mechanism comprising main springs is discharged rapidly to convert the stored potential energy into kinetic energy. Generally the charging cam element is used to provide force to the closing latch causing the energy to be transferred to a cam element causing uncontrolled rotation.

[004] Currently, the spring charge mechanisms in a circuit breaker uses a rotating cam element to charge the main springs of the mechanism which further stores the potential energy that is responsible for driving mechanism within the circuit breaker. Charging is generally accomplished with the help of a motorized gearbox that rotates a charging shaft and consequently the cam coupled to it. The charging circuit is acutely interconnected to the closing circuit, wherein the closing latch in the closing circuit takes its input force through a series of linkages from the cam element of the charging circuit. Thus, the closing latch is dependent upon the cam element which partake its function in both the charging and closing circuit of the operation mechanism.

[005] Since the closing latch is dependent on cam element to provide driving motion, high static forces, originating from mechanism springs, act at all times on the cam element until closing latch is released. Once closing latch is released, high force is imparted to the cam element and this contributes to uncontrolled rotation of the cam element. This may cause issues within the motorized gearbox used to electrically charge the circuit breaker mechanism. The rotation of the cam element, if not limited may cause damage to the sensitive cam surface when it hits the follower assembly in an event of over rotation. Inadvertent recharging phenomenon is also observed in some cases where cam element rotates with excessively high speed.

[006] Thus, in view the hitherto drawbacks of the existing spring charge mechanism, there exists a dire need to provide an improved assembly in a circuit breaker that relieves the closing circuit in a circuit breaker from damages due to static forces of the main springs and also protects the charging circuit accessories against undue rotation of a charging shaft..

SUMMARY OF THE INVENTION

[007] 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.

[008] An object of the present invention is to provide an assembly to prevent uncontrolled/undue rotation of a cam element in a charging circuit mechanism when a circuit breaker mechanism is switched ON.

[009] Another object of the present invention is to provide an assembly to protect the charging circuit accessories in a circuit breaker against violent rotation of charging shaft.

[0010] Yet another object of the present is to provide an assembly to provide an assembly to improve mechanical life and reliability of latch assembly and sensitive charging circuit accessories in a circuit breaker.

[0011] Accordingly, the present invention provides an improved assembly in a circuit breaker to enable a charging circuit cam element to remain independent of closing latch assembly by releasing the charging circuit cam element in an event when the circuit breaker is in close condition.

[0012] In one implementation, the present invention provides a dual follower assembly for performing dual function of charging the main springs providing for input force for the circuit breaker as well as providing a closing force input to closing latch in a circuit breaker. The assembly consists of a Roller to take input from charging cam to charge main springs and Rivets to provide closing force to closing latch as also the circuit breaker itself. These components are mounted on the follower plate to form the dual follower assembly.

[0013] In one implementation, the present invention provides a compound closing latch component which takes its own input from the dual follower assembly independently, to generate closing force on the close shaft. In doing so it liberates the charging circuit cam of the mechanism from the closing circuit resulting in the novelty of current invention.

[0014] In one implementation, the present invention provides a mechanism in a circuit breaker that enables a rotating cam element in a charging circuit independent of the closing circuit wherein the rotating cam element is released instantaneously after the completion of a charging operation and subsequently providing a closing force input to a closing latch assembly.

[0015] In one implementation, as the closing circuit is independent of cam, mechanism main springs do not act on cam at ready to close condition of breaker (i.e., when mechanism is fully charged).

[0016] In one implementation, a motorized gearbox is safeguarded from any unrestricted rotation of the cam and hence charging shaft since they are released as soon as charging operation is complete.

[0017] In one implementation, charging force for the charging circuit remains constant since sensitive surface of cam bears no undue force after charging operation is complete, hence protecting it from any damage.

[0018] In one implementation, phenomenon of recharging of follower assembly due to excessive charging cam rotation is eliminated.

[0019] Accordingly, in one implementation, an improved circuit breaker having at least one rotatable charging cam coupled to at least one shaft at one end and at least one roller of at least one dual follower assembly at other end is provided. The rotatable charging cam adapted to rotate with said shaft for charging said at least one spring in said dual follower assembly during a charging operation, and release at the end of said charging operation of said circuit breaker. Further, the dual follower assembly is adapted to provide closing force to close at least one latch to perform closing operation of said circuit breaker.

[0020] In one implementation, as compared to the available mechanism in circuit breakers in the prior-art, the rotatable charging cam profile reaches its crest and then it gets released during the last charging stroke as compound closing latch takes input motion from rivet on dual follower assembly and latches onto close shaft. Further, the potential energy of the main springs are transmitted by said dual follower assembly instead of charging cam itself thus allowing freedom of rotation to said charging cam.

[0021] 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 above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0022] Figure 1 illustrates a side view of a circuit breaker in a charge OFF condition, in accordance with an embodiment of the present subject matter.

[0023] Figure 2 illustrates an overview of circuit breaker in a charge OFF condition, in accordance with an embodiment of the present subject matter.

[0024] Figure 3 illustrates a side view of a circuit breaker in a ready to close condition, in accordance with an embodiment of the present subject matter.

[0025] Figure 4 illustrates an overview of a circuit breaker in a ready to close condition, in accordance with an embodiment of the present subject matter.

[0026] Figure 5 illustrates a side view of a circuit breaker in a discharged OFF condition, in accordance with an embodiment of the present subject matter.

[0027] Figure 6 illustrates a side view of a circuit breaker in a discharged OFF condition, in accordance with an embodiment of the present subject matter.

[0028] 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

[0029] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0030] 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.

[0031] 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.

[0032] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0033] 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.

[0034] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0035] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0036] Figure 1 illustrates the side view of a circuit breaker in a charge OFF condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0037] Figure 2 illustrates the overview of a circuit breaker in a charge OFF condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0038] Figure 3 illustrates the side view of a circuit breaker in a ready to close condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0039] Figure 4 illustrates the overview of a circuit breaker in a ready to close condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0040] Figure 5 illustrates the side view of a circuit breaker in discharged OFF condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0041] Figure 6 illustrates the overview of a circuit breaker in discharged OFF condition. A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of electronic circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0042] Referring now to figure 1 and 2, in one implementation, spring charge driving mechanism (12) is rigidly fixed onto a circuit breaker housing (11) by means of mounting screws. The circuit breaker housing (11) encloses a moving pole contact (14) assembly and a fixed terminal contact (13). When spring charge driving mechanism (12) is being charged, charging shaft (20) is rigidly coupled to a Charging Cam element (19) by means of locking profile is rotated about an axis. The charging shaft (20) is free to pivot about its axis mounted onto roller bearings in the mechanism side plate (16). As charging cam (19) rotates, its cam profile provides input to a dual follower assembly (21), to which the mechanism main springs are connected. As a consequence of Dual Follower Assembly (21) output main springs are compressed and their energy is stored as input potential energy for the spring charge driving mechanism (12). When the Charging Cam element (19) profile reaches its crest and then is released, the spring charge driving mechanism (12) is said to be in charged OFF condition. The energy is stored by means of the compound closing latch assembly (18) by latching onto a Close Shaft (17) which actuates switching ON condition in the circuit breaker.

[0043] Referring now to the figure 3 and 4, the compound closing latch assembly (18) takes an input motion from Rivet (212) on dual follower assembly and latches onto the close shaft (17). The spring charge Driving Mechanism (12) is now in ready to close condition.

[0044] Referring now to the figure 5 and 6, on rotation of Close Shaft (17), the compound closing latch (18) is de-latched and releasing the dual follower assembly (21) and thus input potential energy of main springs is converted to kinetic energy of mechanism linkages. These impart rotational motion to a pole shaft (15) and then to the moving pole contacts (14) to make a contact with the fixed terminal contacts (13). Spring charge driving mechanism (12) gets latched in this position and circuit breaker is now in discharged OFF condition.

[0045] Accordingly, in one implementation, an improved circuit breaker having at least one rotatable charging cam (19) coupled to at least one shaft (20) at one end and at least one roller (211) of at least one dual follower assembly (21) at other end is provided. The rotatable charging cam (19) adapted to rotate with said shaft (20) for charging said at least one spring in said dual follower assembly (21) during a charging operation, and release at the end of said charging operation of said circuit breaker. Further, the dual follower assembly (21) is adapted to provide closing force to close at least one latch (18) to perform closing operation of said circuit breaker.

[0046] Some of the important features of the present invention, considered to be noteworthy are mentioned below:
1. The present invention discloses an assembly in a circuit breaker which enables the charging cam element to remain independent of closing circuit of the driving mechanism.
2. Charging cam element is released when breaker is in ready to close condition thereby preventing any damages due to static force.
3. Sensitive cam surface of the charging cam element only bear force during charging operation and no other undue forces is experience, thereby improving the mechanical life and reliability.
4. Charging circuit accessories like motorized gearbox are protected as there is no violent rotation of charging shaft
5. Possibility of mechanism spring recharging phenomenon due to high velocity imparted during closing operation charges the dual follower assembly unintentionally is circumvented in totality because cam is independent of closing circuit.
,CLAIMS:1. A circuit breaker CHARACTERIZED IN THAT comprising:
at least one rotatable charging cam (19) coupled to at least one shaft (20) at one end and at least one roller (211) of at least one dual follower assembly (21) at other end, wherein said rotatable charging cam (19) adapted to:
rotate with said shaft (20) for charging said at least one spring in said dual follower assembly (21) during a charging operation;
release at the end of said charging operation of said circuit breaker; and
said dual follower assembly (21) adapted to provide closing force to close at least one latch (18) to perform closing operation of said circuit breaker.
2. The circuit breaker as claimed in claim 1, comprises:
a driving mechanism (12) fixed onto said circuit breaker’s housing (11);
said housing (11) encloses at least one moving pole contact assembly (14) and at least one fixed terminal contact assembly (13);
said shaft (20) coupled to said rotatable charging cam (19) at one end and rotatably fixed at other end, adapted to rotate about its axis.
3. The circuit breaker as claimed in claims 1 and 2, wherein said dual follower assembly (21) comprises:
said roller (211) coupled to said cam (19) and adapted to receive input from said cam (19) rotated;
said spring adapted to be compressed in response to said input received from said cam (19) rotated and thereby store an energy as an input potential energy, charging said at least one spring in said dual follower assembly (21) during a charging operation.
4. The circuit breaker as claimed in claim 3, wherein said spring store said energy by means of at least one compound closing latch (18) by latching onto at least one close shaft (17) for said driving mechanism (12) is responsible for switching ON the circuit breaker.
5. The circuit breaker as claimed in any of the preceding claims, wherein said compound closing latch (18) takes input motion from at least one rivet (212) on at least one dual follower assembly (21) and latches onto at least one close shaft (17).
6. The circuit breaker as claimed in any of the preceding claims, wherein, on rotation of said close shaft (17), said compound closing latch (18) is adapted to de-latch and release said dual follower assembly (21), to convert said stored input potential energy of said spring into kinetic energy of at least one said pole shaft (15).
7. The circuit breaker as claimed in any of the preceding claims, wherein said kinetic energy impart rotational motion to said pole shaft (15) and move said pole contacts (14) to communicate with said fixed terminal contacts (13), thereby enabling said driving mechanism (12) to get latched.
8. The circuit breaker as claimed in any of the preceding claims, characterized in that:
said rotatable charging cam (19) is adapted to reach its crest and then get released during a last charging stroke of charging operation as said compound closing latch (18) takes input motion from said rivet (212) on said dual follower assembly (21) and latches onto said close shaft (17).
9. The circuit breaker as claimed in any of the preceding claims, characterized in that said input potential energy of said main spring is transmitted by said dual follower assembly (21) to said pole shaft (15).