1. Field
The disclosed concept relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The disclosed concept also relates to charging assemblies for circuit breakers.
2. Background Information
Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism, which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions as detected, for example, by a trip unit. The electrical contact assemblies include stationary electrical contacts and corresponding movable electrical contacts that are separable from the stationary electrical contacts.
Among other components, the operating mechanisms of some stored energy circuit breakers, for example, typically include a pole shaft, a trip actuator assembly, a closing assembly and an opening assembly. The trip actuator assembly responds to the trip unit and actuates the operating mechanism. The closing assembly and the opening assembly may have some common elements, which are structured to move the movable electrical contacts between a first, open position, wherein the movable and stationary electrical contacts are separated, and a second, closed position, wherein the movable and stationary electrical contacts are electrically connected.
The closing assembly includes a chargeable stored energy mechanism such as, for example and without limitation, a closing spring, as well as a close latch, a charging handle, and a close button to actuate (e.g., discharge) the closing spring to facilitate the closing process. The charging handle for the closing assemblies of some circuit breakers includes a ratcheting mechanism with a pawl that engages recesses or teeth in a ratchet at the base of the handle in an attempt to resist undesired handle backlash. It is possible, however, for the close latch or other closing assembly components to become damaged, for example, by forces and an associated collision of components resulting from a sudden release of the charging handle during the charging process, before the pawl can stop the backwards rotation.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in charging assemblies therefor.
These needs and others are met by embodiments of the disclosed concept, which are directed to a charging assembly for an electrical switching apparatus, such as a circuit breaker. Among other benefits, the charging assembly includes a close latch protection feature for resisting damage to circuit breaker components that can be caused by sudden release of the charging handle, particularly early in the charging process.
As one aspect of the disclosed concept, a charging assembly is provided for an electrical switching apparatus. The electrical switching apparatus includes a housing, separable contacts enclosed by the housing, and an operating mechanism for opening and closing the separable contacts. The operating mechanism includes a stored energy mechanism. The charging assembly comprises: a cam shaft structured to be pivotably coupled to the housing, the cam shaft including a first end, a second end disposed opposite and distal from the first end, and a number of cams disposed between the first end and the second end; a latch lobe coupled to the cam shaft at or about the first end; a charging handle coupled to the cam shaft at or about the second end, the charging handle being structured to pivot a number of strokes, each stroke pivoting the cams a predetermined amount; at least one rocker arm structured to be pivotably coupled to the housing by a pivot, the at least one rocker arm including a first portion, a second portion and a third portion, the first portion cooperating with a corresponding one of the cams, the second portion being structured to translate movement of the cams into movement of the stored energy mechanism to charge the stored energy mechanism, the third portion being disposed proximate to the pivot; a close prop including a first end and a second end disposed opposite and distal from the first end, the second end including a roller cooperating with the latch lobe; and a close D-shaft structured to be pivotably coupled to the housing, the close D-shaft comprising a recess and a close latch, the close D-shaft being pivotable between a latched position corresponding to the close latch restricting movement of the first end of the close prop, and an unlatched position corresponding to the close prop being movable. The third portion of the at least one rocker arm is structured to cooperate with the close D-shaft at or about the recess to hold the close latch in the unlatched position until the charging handle has been pivoted a predetermined number of strokes to charge the stored energy mechanism a predetermined amount. After the predetermined number of strokes is achieved, the third portion of the at least one rocker arm releases the close D-shaft, thereby permitting the close latch to move to the latched position.
When the charging handle has been pivoted the predetermined number of strokes, the cam shaft may be correspondingly pivoted a predetermined distance. The predetermined distance may correspond to the latch lobe being disposed sufficiently distal from the roller of the close prop in order that release of the charging handle and corresponding backward rotation of the cam shaft would not result in a collision between the roller and the latch lobe. The third portion of the rocker arm may have a profile, and wherein the profile is structured to cooperate with the close D-shaft at or about the recess.
An electrical switching apparatus employing the aforementioned charging assembly is also disclosed.
A full understanding of the disclosed concept can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
Directional phrases used herein, such as, for example, front, back, top, bottom, clockwise, counterclockwise and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.
As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.
As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
As shown in
A close prop 126, which includes a first end 104 and a second end 106 disposed opposite and distal from the first end 104, is also pivotably coupled to the circuit breaker housing 4. The second end 106 of the close prop 126 includes a roller 132, which cooperates with the latch lobe 112, as best shown in
It will be appreciated that the third portion 124 of the rocker arm 118 cooperates with the close D-shaft 134 and thereby functions as a close latch protection feature/mechanism to resist undesired damage to charging assembly components caused, for example and without limitation, by a sudden release of the charging handle early in the charging process. More specifically, in conventional circuit breakers (not shown) a sudden release of the charging handle during charging allows the spring-driven rocker arms to drive the cam shaft rapidly backwards until it is stopped and held by the handle fixed pawl of the latching handle mechanism. If this release takes place during the first few handle strokes of the charging handle (e.g., early in the charging process), the close latch components (e.g., without limitation, close prop; roller; latch lobe) may collide before the handle fixed pawl can stop the rotation. Such a collision could rotate the arms of the close prop and damage the close latch if the close D-shaft has already been reset (e.g., if the close D-shaft has been rotated by its reset spring to stop passage of the close prop). The disclosed concept addresses and overcomes the foregoing disadvantages of the prior art by incorporating the aforementioned close latch protection feature/mechanism as a unique feature of the rocker arm 118.
Specifically, the rocker arm 118 cooperates with the close D-shaft 134 at or about the recess 136 thereof to hold the close latch 138 in the unlatched position (
Continuing to refer to
Referring again to FIGS. 2 and 3A-6B, the housing 4 of the example circuit breaker 2 includes at least one side plate 14. The side plate 14 includes a stop 16, and the close D-shaft 134 includes a lever 140 (
The close latch protection feature/mechanism will now be described in greater detail. Specifically, as previously discussed, the rocker arm 118 includes a third portion 124 proximate the pivot 12. The third portion 124 has a profile 150. It is this profile 150 that cooperates with the close D-shaft 134 at or about the recess 136 (
The radius of curvature of the third segment 156 is greater than the radius of curvature of the second segment 154. It will, however, be appreciated that any known or suitable alternative shape, configuration and/or type of profile other than the profile 150 shown and described herein, could be employed without departing from the scope of the disclosed concept. The interaction of the profile 150 with the close D-shaft 134 in order to control movement of the close latch 138 in accordance with the disclosed concept, is best shown in the enlarged views of
Referring again to
While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.
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Number | Date | Country | |
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20120103775 A1 | May 2012 | US |