Patent Grant
7586394
This application is related to commonly assigned, co-pending:
U.S. patent application Ser. No. 11/696,810, filed Apr. 5, 2007, entitled “ELECTRICAL SWITCHING APPARATUS AND TRIP ACTUATOR ASSEMBLY THEREFOR”;
U.S. patent application Ser. No. 11/696,815, filed Apr. 5, 2007, entitled “ELECTRICAL SWITCHING APPARATUS, AND TRIP ACTUATOR ASSEMBLY AND RESET ASSEMBLY THEREFOR”; and
U.S. patent application Ser. No. 11/696,812, filed Apr. 5, 2007, entitled “ELECTRICAL SWITCHING APPARATUS AND TRIP ACTUATOR RESET ASSEMBLY THEREFOR,” which are hereby incorporated herein by reference.
1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to trip actuator reset assemblies for electrical switching apparatus, such as circuit breakers. The invention also relates to lever arm assemblies for circuit breaker trip actuator reset assemblies.
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.
Among other components, the operating mechanisms of some low-voltage circuit breakers, for example, typically include a pole shaft and a trip actuator assembly. The pole shaft pivots during opening and closing operations of the circuit breaker, which operations respectively correspond to electrical contact assemblies being opened (e.g., contacts separated) and closed (e.g., contacts electrically connected). The trip actuator assembly typically includes a trip bar, a trip actuator such as, for example, a solenoid, and a cradle assembly. The cradle assembly is coupled to and is cooperable with the pole shaft. The trip actuator (e.g., solenoid) has a spring, a coil which is energized by the trip unit in response to the electrical fault condition, and an actuating element such as, for example, a plunger. Normally (e.g., in the absence of the electrical fault condition), the plunger is latched (e.g., by a magnet) in a retracted position. When the coil is energized, in response to the electrical fault condition, the magnetic force that holds the plunger in the retracted position is overcome and the spring biases the plunger to an extended position and maintains it there. When the plunger extends, it causes the trip bar to pivot and trip open the electrical contact assemblies.
Subsequently, both the electrical contact assemblies and the trip actuator must be reset. The trip actuator assembly operates in conjunction with the pole shaft to perform the resetting operation. Specifically, when the circuit breaker operating mechanism is reset, the pole shaft pivots, thereby moving the cradle assembly. The cradle assembly then pivots a reset arm which, in turn, depresses the actuating element (e.g., plunger) and resets the trip actuator (e.g., solenoid). The travel and actuating force of the plunger are relatively limited. Therefore, any misalignment between circuit breaker components can adversely affect the reset operation of the trip actuator assembly. For example, because the pole shaft, the cradle assembly, and the reset lever are coupled together, dimensional variations and/or assembly errors can result in imprecise interaction among these components. By way of example, the pole shaft and the cradle assembly may, for example, move in a manner which tends to over-rotate the reset lever of the trip actuator reset assembly. More specifically, over-rotation occurs when the reset lever has completely depressed the plunger, thus resetting the trip actuator, but the pole shaft and/or the cradle assembly continue to move causing the reset lever to continue to apply pressure to the plunger.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in trip actuator reset assemblies therefor.
These needs and others are met by embodiments of the invention, which are directed to a lever arm assembly for trip actuator reset assemblies of electrical switching apparatus such as, for example, circuit breakers, wherein the lever arm assembly can accommodate dimensional and/or assembly imperfections and conditions (e.g., over-rotation of the pole shaft, cradle assembly and/or reset lever) caused thereby, in order to avoid damage to the circuit breaker and to accurately and consistently reset the trip actuator.
As one aspect of the invention, a lever arm assembly is provided for a trip actuator reset assembly of an electrical switching apparatus including a housing, separable contacts enclosed by the housing, and an operating mechanism structured to open and close the separable contacts. The operating mechanism includes a pole shaft. The trip actuator reset assembly includes a cradle assembly pivotably coupled to the pole shaft, a reset lever pivotably coupled to the housing, and a trip actuator including an actuating element. The cradle assembly is movable among a first position corresponding to the separable contacts being closed, and a second position corresponding to the separable contacts being open. The actuating element is structured to move the reset lever in response to a trip condition. The lever arm assembly comprises: at least one linking element including a first end structured to be pivotably coupled to the cradle assembly, a second end disposed opposite and distal from the first end, and a pivot structured to pivotably couple such linking element to the housing; and a deflection assembly comprising a deflection member disposed on a corresponding one of the at least one linking element and being structured to move the reset lever. After the trip condition, the actuating element of the trip actuator is structured to be reset. When the cradle assembly moves from the first position toward the second position, the cradle assembly moves the corresponding one of the at least one linking element, thereby moving the deflection member into engagement with the reset lever, in order to pivot the reset lever. When the deflection member pivots the reset lever, the reset lever moves the actuating element of the trip actuator, thereby resetting the trip actuator, and after the trip actuator has been reset, if the cradle assembly continues to move beyond the second position, then the deflection assembly deflects to accommodate any additional motion of the cradle assembly.
The corresponding one of the at least one linking element may comprise an elongated arm including a first end, a second end, a first edge, a second edge disposed opposite the first edge, a pivot disposed at or about the second end, and at least one recess disposed on the first edge proximate the pivot. The deflection assembly may be coupled to the first edge at or about the at least one recess. The deflection assembly may further comprise a bias element substantially disposed within a corresponding one of the at least one recess, wherein the bias element is structured to bias the deflection member toward engagement with the reset lever. The at least one recess may be a first recess and a second recess disposed on the first edge of the elongated arm proximate the first recess. The deflection member may be a generally planar member having a first side facing the first edge of the elongated arm, a second side disposed opposite the first side, a first end, a second end disposed opposite the first end of the generally planar member, and a tab extending outwardly from the first side of the generally planar member at or about the first end of the generally planar member. The second end of the generally planar member may be structured to cooperate with the pivot, and the tab may movably engage the first edge of the elongated arm at or about the second recess.
The pivot may comprise a generally circular portion disposed at or about the second end of the elongated arm. The generally circular portion may include a hole. A pin member may extend through the hole and be structured to be pivotably coupled to the housing of the electrical switching apparatus. A protrusion may extend outwardly from the generally circular portion, wherein the protrusion is generally parallel with respect to the first edge of the elongated arm and is spaced apart from the first edge of the elongated arm. The second end of the generally planar member may be disposed between the protrusion and the first edge of the elongated arm.
The cradle assembly may include a first end pivotably coupled to the pole shaft, a second end disposed opposite and distal from the first end of the cradle assembly, and at least one side member extending between the first end of the cradle assembly and the second end of the cradle assembly. The at least one linking element may further comprise a connecting link structured to interconnect the elongated arm and the cradle assembly, wherein the connecting link includes a first end structured to be pivotably coupled to a corresponding one of the at least one side member, and a second end pivotably coupled to the first end of the elongated arm.
As another aspect of the invention, a trip actuator reset assembly is provided for an electrical switching apparatus including a housing, separable contacts enclosed by the housing, and an operating mechanism structured to open and close the separable contacts. The operating mechanism includes a pole shaft. The trip actuator reset assembly comprises: a cradle assembly including a first end structured to be pivotably coupled to the pole shaft, a second end disposed opposite and distal from the first end, and at least one side member extending between the first end and the second end, the cradle assembly being movable among a first position corresponding to the separable contacts being closed, and a second position corresponding to the separable contacts being open; a reset lever structured to be pivotably coupled to the housing; a trip actuator including an actuating element which, in response to a trip condition, moves the reset lever; and a lever arm assembly comprising: at least one linking element including a first end pivotably coupled to a corresponding one of the at least one side member of the cradle assembly, a second end disposed opposite and distal from the first end of the at least one linking element, and a pivot structured to pivotably couple the at least one linking element to the housing, and a deflection assembly comprising a deflection member disposed on a corresponding one of the at least one linking element and being cooperable with the reset lever. After the trip condition, the actuating element of the trip actuator must be reset. When the cradle assembly moves from the first position toward the second position, the at least one side member of the cradle assembly moves the corresponding one of the at least one linking element, thereby moving the deflection member into engagement with the reset lever, in order to pivot the reset lever. When the deflection member pivots the reset lever, the reset lever moves the actuating element of the trip actuator, thereby resetting the trip actuator, and after the trip actuator has been reset, if the cradle assembly continues to move beyond the second position, then the deflection assembly deflects to accommodate any additional motion of the cradle assembly.
The corresponding one of the at least one linking element of the lever arm assembly may comprise an elongated arm including a first end, a second end, a first edge, a second edge disposed opposite the first edge, a pivot disposed at or about the second end of the elongated arm, and at least one recess disposed on the first edge proximate the pivot of the elongated arm. The deflection member of the deflection assembly may be coupled to the first edge of the elongated arm at or about the at least one recess. The deflection assembly may further comprise a bias element substantially disposed within a corresponding one of the at least one recess, wherein the bias element biases the deflection member toward engagement with the reset lever.
As another aspect of the invention, an electrical switching apparatus comprises: a housing; separable contacts enclosed by the housing; an operating mechanism structured to open and close the separable contacts, the operating mechanism including a pole shaft; and a trip actuator reset assembly comprising: a cradle assembly including a first end pivotably coupled to the pole shaft, a second end disposed opposite and distal from the first end, and at least one side member extending between the first end and the second end, the cradle assembly being movable among a first position corresponding to the separable contacts being closed, and a second position corresponding to the separable contacts being open, a reset lever pivotably coupled to the housing, a trip actuator including an actuating element which, in response to a trip condition, moves the reset lever, and a lever arm assembly comprising: at least one linking element including a first end pivotably coupled to the corresponding one of the at least one side member of the cradle assembly, a second end disposed opposite and distal from the first end of the at least one linking element, and a pivot pivotably coupling the at least one linking element to the housing, and a deflection assembly comprising a deflection member disposed on a corresponding one of the at least one linking element and being cooperable with the reset lever. After the trip condition, the actuating element of the trip actuator must be reset. When the cradle assembly moves from the first position toward the second position, the corresponding one of the at least one side member of the cradle assembly moves the corresponding one of the at least one linking element, thereby moving the deflection member into engagement with the reset lever, in order to pivot the reset lever. When the deflection member pivots the reset lever, the reset lever moves the actuating element of the trip actuator, thereby resetting the trip actuator, and after the trip actuator has been reset, if the cradle assembly continues to move beyond the second position, then the deflection assembly deflects to accommodate any additional motion of the cradle assembly.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
For purposes of illustration, embodiments of the invention will be described as applied to low-voltage circuit breakers, although it will become apparent that they could also be applied to a wide variety of electrical switching apparatus (e.g., without limitation, circuit switching devices and other circuit interrupters, such as contactors, motor starters, motor controllers and other load controllers) other than low-voltage circuit breakers and other than low-voltage electrical switching apparatus.
Directional phrases used herein, such as, for example, left, right, top, bottom, upper, lower, front, back, clockwise and 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 terms “actuator” and “actuating element” refer to any known or suitable output mechanism (e.g., without limitation, trip actuator; solenoid) for an electrical switching apparatus (e.g., without limitation, circuit switching devices, circuit breakers and other circuit interrupters, such as contactors, motor starters, motor controllers and other load controllers) and/or the element (e.g., without limitation, stem; plunger; lever; paddle; arm) of such mechanism which moves in order to manipulate another component of the electrical switching apparatus.
As employed herein, the term “fastener” shall mean a separate element or elements which is/are employed to connect or tighten two or more components together, and expressly includes, without limitation, rivets, pins, screws, bolts and the combinations of bolts and nuts (e.g., without limitation, lock nuts) and bolts, washers and nuts.
As employed herein, the term “aperture” refers to any known or suitable passageway into or through a component and expressly includes, but is not limited to, openings, holes, gaps, slots, slits, recesses, and cut-outs.
As employed herein, the term “trip condition” refers to any electrical event that results in the initiation of a circuit breaker operation in which the separable contacts of the circuit breaker are tripped open, and expressly includes, but is not limited to, electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions, receipt of an input trip signal, and a trip coil being energized.
As employed herein, the term “linking element” refers to any known or suitable mechanism for connecting one component to another and expressly includes, but is not limited to, rigid links (e.g., without limitation, arms; pins; rods), flexible links (e.g., without limitation, wires; chains; ropes), and resilient links (e.g., without limitation, springs).
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).
The trip actuator reset assembly 50 includes a cradle assembly 52 (best shown in
The cradle assembly 52 is movable among a first position (
The housing 4 of the example circuit breaker 2 includes the mounting surface 6 and first and second side plates 104,106 extending outwardly therefrom. The first side plate 104 has first and second opposing ends 110, 112, a bottom edge 114, which engages the mounting surface 6 of the circuit breaker housing 4, and a top edge 116. The aforementioned cradle assembly 50 is disposed on the second side 152 of the first side plate 104, between the first and second side plates 104, 106. The example first side plate 104, in combination with a number of protrusions 30,32 and fastener 34, all of which extend outwardly from the mounting surface 6 of the circuit breaker housing 4, secure the trip actuator 102 to the mounting surface 6. More specifically, the fastener 34 engages a hole 36 in protrusion 32, in order to secure the trip actuator 102 in the desired orientation with respect to the first side plate 104. In the example of
As shown in
Referring to
Specifically, in response to the trip condition, the actuating element 130 of the trip actuator 102 extends, as shown in phantom line drawing in
Continuing to refer to
The pivot 208 of the example elongated arm 202 is disposed at the second end 206 thereof, and includes a generally circular portion 238 including a hole 240, a pin member 242 extending through the hole 240 and pivotably coupling the elongated arm 202 to the side plate 104 (
As shown, for example, in
Accordingly, it will be appreciated that the disclosed trip actuator reset assembly 100 and lever arm assembly 200 therefor, provide a mechanism for accommodating, for example and without limitation, misalignment and/or over-rotation associated therewith, in order to effectively, consistently reset the trip actuator 102 of the circuit breaker 2 (
While specific embodiments of the invention 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 invention 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 | |
|---|---|---|---|
| 20090015359 A1 | Jan 2009 | US |
