The present disclosure relates generally to circuit breakers, and more particularly, to blocking members for circuit breakers having a quick-make feature.
Circuit breakers are automatically operated electrical switches designed to protect electrical circuits from damage caused by overload or short circuit. A basic function is to detect a fault condition and interrupt current flow.
Typically, in a circuit breaker, the electrical contacts are held closed by a latch mechanism having separate first and second engageable members. Initially, the first member may be positioned to contact the second member to restrain and prevent movement of the second member so that the electrical contacts are maintained in a closed position. The latch mechanism may be triggered by moving or pivoting the first member out of engagement with the second member to allow the second member to move and open the electrical contacts.
In addition, often a circuit breaker includes a “quick-make” feature that allows electrical contacts to be closed quickly from the fully open position to the closed position. The speed of the closing of the electrical contacts is independent of how a handle operated by a user is used to effect the closing of the electrical contacts from the open position, i.e., the contact speed is independent of how fast or slow the handle is moved. Traditional over-center toggle mechanisms achieve a change in linkage orientation with respect to spring tension so that at a certain critical point in the handle movement, a balance of forces will cause the quick rotation of linkages to snap the contacts closed.
Shortcomings of the prior art are overcome and additional advantages are provided through the provision, in one embodiment, of a blocking member for an actuator having a movable arm for effecting a quick-make feature. The blocking member includes, for example, an elongated member having a first end and a second end, and wherein a portion of the elongated member being configured so that the blocking member disposed in a first position engages a portion of the movable arm of the actuator to restrain movement of the movable arm, and so that the blocking member disposed in a second position disengages from the portion of the movable arm of the actuator to permit movement of the movable arm.
In another embodiment, a circuit breaker having a quick-make feature which includes, for example, a frame, a stationary electrical contact attached to the frame, a movable arm having a first end attachable to the frame and a second end having an electrical contact releasably contactable with the stationary electrical contact, and an actuator mechanism. The actuator mechanism includes a main biasing means operable to apply a first force to move the movable arm in a first direction to open the electrical contacts, a contact biasing means operable to apply a second force to move the movable arm in a second direction to close the electrical contacts, and a blocking member configured so that the blocking member in a first position engages a portion of the movable arm to restrain movement of the movable arm by the main biasing means and maintain the electrical contacts open, and so that the blocking member disposed in a second position disengages from the portion of the movable arm to permit movement of the movable arm by the contact biasing means to close the electrical contacts.
In another embodiment, a method for moving a movable arm to effect a quick-make feature. The method includes, for example, engaging the movable arm with a blocking member to restrain movement of the movable arm in a first direction, and disengaging the movable arm from the blocking member to allow movement of the movable arm in the first direction.
In another embodiment, a method for actuating a circuit breaker for opening and closing electrical contacts. The method includes, for example, engaging a movable arm with a blocking member to restrain movement of the movable arm in a first direction and maintain the electrical contacts open, and disengaging the blocking member from the movable arm to allow movement of the movable arm in the first direction to close the electrical contacts.
The foregoing and other features, aspects and advantages of this disclosure will become apparent from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings, wherein:
Embodiments of the present disclosure and certain features, advantages, and details thereof, are explained more fully below with reference to the non-limiting examples illustrated in the accompanying drawings. Descriptions of well-known materials, processing techniques, etc., are omitted so as not to unnecessarily obscure the disclosure in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the present disclosure, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and/or arrangements, within the spirit and/or scope of the underlying inventive concepts will be apparent to those skilled in the art from this disclosure.
The present disclosure in some embodiments employ a yieldable support such as a flexure member or plurality of rigid links having a rigid configuration or mode for supporting a force in compression, and which upon tripping or buckling transitions to a flexible configuration or compliant mode. Such a technique may be employed in an actuator/trip mechanisms for triggering systems such as circuit breakers. A blocking member may also be provided for temporarily limiting movement of such an actuator/trip mechanism thereby making the actuator/trip mechanism a quick-make actuator/trip mechanism.
As will be appreciated from the discussion below, the technique of the present disclosure may provide an actuator and circuit breaker operable for maintaining the electrical contacts in a closed position and for opening the electrical contacts which may provide a simplified mechanism with less parts, at less costs, and possibly more easily manufactured compared to an actuator and circuit breaker employing a latch mechanism for maintaining the electrical contacts in a closed position and for opening the electrical contacts. Such a technique of the present disclosure may provide circuit breaker having enhanced performance characteristics compared to conventional circuit breaker employing a latching mechanism.
Circuit breaker 10 generally includes a frame 20, a stationary contact arm 30, a movable contact arm 40, and an actuator/trigger mechanism 100. Actuator/trigger mechanism 100 may generally include a yieldable support 110, a handle 120, a crank 130, a blocking member 150, and a trip bar 160. As described in greater detail below, the yieldable support may have a rigid configuration defining a straight axis and a flexible configuration defining a non-straight axis. The yieldable support is operable in the rigid configuration to support a compression force along the straight axis for use in charging or energizing the circuit breaker and maintaining the circuit breaker in a closed configuration. The yieldable support is operable in the flexible configuration or resilient bent configuration to allow the circuit breaker to quickly transition to an open configuration.
As shown in
Initially as shown in
In addition, as shown in
As further illustrated in
As described below, blocking member 150 along with yieldable support 110, movable contact arm 40, and crank 130 allows circuit breaker 10 facilitate a quick-make feature where the contacts may be closed quickly. For example, the electrical contacts may be closed on the order of a few milliseconds from the fully open position to the closed position. As noted in
With reference to
Once stop 44 is no longer restrained in cutout 152, as shown in
From the present description and with reference to
As described in greater detail below, the latch-free circuit breaker may have a quick-break feature provided generally by yieldable support 110 operable in, for example, two configurations or modes, a rigid configuration or rigid mode and a flexible configuration or compliant mode. As noted above and as shown in
In addition, as shown in
For example, if crank 130 is in its counterclockwise position as shown
With reference again to
From the present description, it will be appreciated that the yieldable support can be readily changed from rigid to compliant with a small energy input in the form of a force, torque, thermal energy, electromagnetic energy, pressure, etc., and likewise the yieldable support can be reset from the compliant mode to the rigid mode with little effort. The yieldable support may be cycled reliably many times between these states.
As described above, the circuit breaker may be disposed in a closed ON position with the yieldable support disposed in a rigid mode. In this mode, the yieldable support may be loaded axially, that is in a direction along a line between the pins, to a large extent and remain at a low stress state that can be retained for an extended period of time, if not indefinitely. The ribbon cross-section of the yieldable support, ribbon thickness, and offset may be chosen such that when the yieldable support is loaded axially, a small input force may be applied to or near the midpoint of the ribbon orthogonal to the axis of the ribbon, so that it will buckle or bend and enter a compliant mode. In this bending or compliant mode, the end displacements may limit the deflection on the order of ⅕ the length of the yieldable support so that the ribbon stresses remain reasonably small and elastic, e.g., so that little or no permanent deformation or damage is imparted to the ribbon. It will be appreciated that with the semicircular cross-sectional shape of the ribbon, the ribbon is asymmetric and may have an asymmetric response to bending or buckling. The offset specification may also affect the asymmetry of bending or buckling.
In this embodiment of the yieldable support, the end mounts may be single or monolithic units made of metal or plastic that can accommodate the ribbon in a slot. Plastic end mounts can be injection molded. Metal end mounts can be injection molded, cast, or machined. Fastening of the ribbon to the mounts may be accomplished by various fasteners, adhesive, brazing, diffusion bonding, etc. The ribbon may include a constant cross-section and be manufactured by a continuous processes such as shape rolling, extrusion, or other means. In other embodiments, the ribbon may have a non-constant cross-section, and manufactured by a non-continuous process. While the disclosure describes and illustrates the yieldable support having semi-circular shape with constant cross-section, it will be appreciated that other shapes and configuration may be suitably employed to provide a rigid mode and a compliant mode. In other embodiments, a yieldable support may comprise a plurality of thin-shaped foils or ribbons such as separate or parallel thin-shaped foils or ribbons and may have a semi-circular or curved-shape cross section. Such as plurality of thin-shaped foils or ribbons may allow for tuning or tailoring the stiffness/bending/buckling characteristics with geometrical constraints. Other geometric properties may affect the load capacity in the rigid mode, response in the compliant mode, and the required force input for transition may include tailoring the yieldable support response based on the width of the ribbon, the length of the ribbon, the thickness of the ribbon, the curvature of the ribbon, the material for the ribbon, the yieldable support placement with respect to the end pivots (e.g., offset), as well as other properties.
In the above embodiments of the yieldable supports, the unconstrained state or configuration may be a rigid state or rigid mode. That is to say, if all outside forces and displacements are removed, the yieldable supports will naturally relax into their unconstrained state or extended state. Thus, restoration from a compliant state or mode to the rigid state or mode may be accomplished by removing the transition energy input or triggering input and allowing the end pins to freely rotate.
As noted above, the transition of the yieldable support from the rigid mode to the compliant mode may include a trip bar, solenoid, and control unit. In other embodiments, other or multiple types of energy can be employed to force the transition of the yieldable support from the rigid mode to the compliant mode. For example, a magnetic or electromagnetic field could be used to alter the state of a metal ribbon, causing it to bend or buckle. In another embodiment, a ribbon may be made from a bimetallic material or strip that is alterable into the compliant state by temperature changes. A torque could be applied to one and/or both end mounts to cause a rotation and a bending or buckling of the yieldable support and a transition from the rigid mode to the compliant mode.
As described below in connection with a rigid mode and a compliant mode, a reference line L extends between the end revolutes. In an embodiment of yieldable support 2110, the two rigid links may be of equal length and thus contain one inner revolute. Inner revolute 2212 may be offset a distance W from end-revolute line L.
In a compliant mode, if all revolutes are free to rotate and there are no other constraints imposed, the yieldable support 2110 will have little or no resistance to the end displacement. For example, since the links are rigid, the yieldable support will accommodate a change in configuration by rotation of the links and displacement of inner revolute 2112 further from end-revolute line L as one of the ends is displaced toward the other in the direction of the end-revolute line. In a rigid mode, inner revolute 2112 of yieldable support 2110 may be restrained. For example, the transformation to a rigid mode is accomplished by removing some of the degrees of freedom, such as by converting the inner revolute to non-rotating or supporting the inner link to limit its movement.
With reference to
With reference again to the blocking member, an actuation mechanism or a circuit breaker may include a blocking member that operates in different axes of rotation (i.e. rotate about some off-axis compared to the axis of rotation of the contact arm). A blocking member may have a fixed point of rotation and include rigid elements or be made compliant or flexible (e.g., configured and providing features similar to a yieldable support) and not have an axis of rotation. For example, in this case such a blocking member may flex to move in and out of a blocking position. The blocking member can be triggered to release via many different means: the crank position, the handle position, a separate button, a logic controller, etc. A blocking member may also be made to be rotation-axis-free. That is, a blocking member may be fastened to a base of a frame and elastically flex to achieve a blocking configuration and a non-blocking configurations, e.g., a compliant embodiment.
In other embodiments, a blocking member may operate passively and not require a separate releasing mechanism, e.g., not required a cutout and stop as previously described above. In this embodiment, a reach of a movable contact arm changes as the system is turned on. The blocking member may be set so it interferes with the movable contact arm for all positions except for when the handle is forward in the ON position. A dual-pivot design of the movable contact arm may establish and control this interference. During a trip, a blocking member may ratchet to allow the movable contact arm to freely pass.
Circuit breaker 3010 generally includes a frame 3020, a stationary contact arm 3030, a movable contact arm 3040, and an actuator/trigger mechanism 3100. Actuator/trigger mechanism 3100 may generally include a yieldable support 3110, a handle 3120, a crank 3130, a blocking member 3150, and a trip bar 3160. As described in greater detail below, yieldable support may have a rigid configuration defining a straight axis and a flexible configuration defining a non-straight axis. The yieldable support is operable in the rigid configuration to support a compression force along the straight axis for use in charging or energizing the circuit breaker and maintaining the circuit breaker in a closed configuration. The yieldable support is operable in the flexible configuration or resilient bent configuration to allow the circuit breaker to quickly transition to an open configuration.
As shown in
Initially, with reference to
In addition, as shown in
As further illustrated in
As described below, blocking member 3150 along with yieldable support 3110, movable contact arm 3040, and crank 3130 allows circuit breaker 3010 facilitate a quick-make feature where the contacts may be closed quickly. For example, the electrical contacts may be closed on the order of a few milliseconds from the fully open position to the closed position.
With reference to
Once stop 3044 is no longer restrained in cutout 3152, as shown in
From the present description with reference to
As described in greater detail below, the latch-free circuit breaker may have a quick-break feature provided generally by yieldable support 3110 operable in, for example, two configurations or modes, a rigid configuration or rigid mode and a flexible configuration or compliant mode. As noted above and as shown in
In addition, as shown in
For example, if crank 3130 is in its counterclockwise position, the contact spring will drive movable contact arm 3040 to rest on cross beam 3138 with some force. To reset the circuit breaker, handle 3120 is moved to the left which causes yieldable support return to its rigid configuration. For example, as described above, yieldable support may have a curved cross-section so that when handle 3120 is moved to the left, the yieldable support snaps back into in to its normal rigid configuration. It will be appreciated that other cross-sections such as round or oval and employing suitable materials and stiffness, may provide a yieldable support which is elastically bendable and which snaps back to its normal rigid configuration after being bent.
With reference again to
From the present description, it will be appreciated that the yieldable support can be readily changed from rigid to compliant with a small energy input in the form of a force, torque, thermal energy, electromagnetic energy, pressure, etc., and likewise the yieldable support can be reset from the compliant mode to the rigid mode with little effort. The yieldable support may be cycled reliably many times between these states.
As described above, the yieldable support may be a resilient member such as a link, links, foil flexure, ribbon, flexure membranes, and a first and a second revolute joints which allow pinned connections. The two end revolute joints or end mounts may be disposed parallel to each other and separated about 25 millimeter to about 40 millimeter for in one or more embodiments of the circuit breakers, or more or less, for example, for other applications. The pin end connections can be joined to other linkages or assemblies as required and can or alternately not be free to rotate.
In the first or rigid mode, the yieldable support may be capable of supporting a large load in the axis of the yieldable support (i.e. following a line at or nearly along a line drawn between the revolute joints or end mounts). In the application in a circuit breaker, the supported axial load may be in the order of about 100 Newtons to about 400 Newtons, and the pins may have a diameter of about 2 millimeters to about 3 millimeters. In the rigid mode, the link is capable of holding this load for an extended period of time (up to the order of 10^8 seconds) and may be resilient to shock vibrations and other harsh environmental conditions such as elevated temperature, humidity, etc.
In the second or compliant mode, the pins may be allowed to contract towards each other with little or no resistance. In the application for use in circuit breakers, the pins may contact towards each other in the compliant mode on the order of ⅕ the separation distance or about 5 millimeters to about 8 millimeters, or other suitable distance depending on the particular retirements of the application.
In the transitioning from the rigid mode to the compliant mode of the yieldable support, an input is required to set or change the configuration of the yieldable support. The input can be in the form of a force, impulse load, torque, thermal energy, electromagnetic energy, pressure, etc. It is desirable to have a low configuration-changing input energy threshold. For example, for use in a circuit breaker, an input energy may be in the form of a force on the order of about 1 newton to about 2 Newtons.
The transiting the yieldable support from the compliant mode to the rigid mode may be achieved by removing the input transition energy and restoring the pins to the original separation distance. No other input may be required. It is noted that the two requirements for a successful transition behave like a logical AND operation: both to be satisfied to return the device to the rigid mode, and if not, the device remains in the compliant mode as shown in Table 1 below.
Thus the device may be classified as having two stable states with transition operations to alter the configuration between these states. These are summarized in Table 2 below.
The technique of the present disclosure may be effectively employed in electrical switching devices where large loads are required to be supported to provide a positive electrical-contact force, yet a small input of energy or force is required to release it. In the case of circuit breakers, tripping of the electrical contacts may be accomplished with a little impulse, such as one supplied by a heated bi-metallic element, or other devices as described above.
Table 3 illustrates the results for 40 millimeter ribbon length and 0.12 mm thickness yieldable supports.
It will be appreciated that the technique of the present disclosure may be used in a toggle-type breaker. In this case, an actuator may be used to make the final arbitration to close the contact arms and would be activated either with another input from the user or via an electronic control unit (which would close the contacts after some self-diagnostic tests.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the disclosure as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term “operably” in conjunction with terms such as coupled, connected, joined, sealed or the like is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., one-piece, integral or monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved according to any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
While the disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This written description uses examples, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
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