Abstract:
A circuit interruption device includes at least one constriction zone. The constriction zone provides for interference with arcing of an electrical signal. The device may include at least one expansion zone. The device may include at least one movable component to assist in creation of the at least one constriction zone. A method of fabrication is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/795,091, filed Mar. 12, 2013, the entire contents of which are incorporated herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention disclosed herein relates to a circuit interruption device that includes at least one constrictive zone that provides for voltage reduction and extinguishing of an electric arc. 
     2. Description of the Related Art 
     A variety of circuit interruption devices have been devised to provide for protection of electrical circuits from electrical overload. A common type of protection device is known as a “circuit breaker.” Generally, a circuit breaker includes a resettable mechanical contact break system. 
     All circuit interruption devices with mechanical contact break systems experience some level of “arcing” during circuit interruption (above a minimum circuit current and voltage). As discussed herein, and as a convention, “arcing” is with reference to an electric signal jumping from one contact to another contact through an air gap. Generally, the greater the current and/or voltage, the greater the probability or magnitude of arcing will be. Arcing can be problematic, particularly for circuit breakers that carry a large load (i.e., are designed to conduct a comparatively high current and/or voltage). Accordingly, circuit breakers are typically larger than desired in order to account for arcing. The excess size results in a more expensive circuit breaker than desired, and additionally results in oversized circuit protection systems. 
     Thus, what are needed are methods and apparatus to provide for reductions in circuit arcing in a mechanical contact break system such as a circuit breaker. Preferably, the methods and apparatus result in decreased size and cost of the break system. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a circuit interruption device is provided. The device includes: at least one line side electrical contact and at least one respective load side electrical contact, the electrical contacts disposed within a case; each of the line side contacts configured for engagement with a respective load side contact, the engagement for electrically connecting an electrical supply with an electrical load; wherein the engagement includes at least one of the line side electrical contact and the respective load side electrical contact moving through an arcing zone to make an electrical connection; and, wherein the arcing zone includes at least one constriction zone adapted for limiting arcing between the respective electrical contacts. 
     In another embodiment, a method for fabricating a circuit interruption device is provided. The method includes: selecting at least one line side contact configured for engagement with a respective load side contact, the engagement for electrically connecting an electrical supply with an electrical load; and, disposing the at least one line side electrical contact and at least one respective load side electrical contact within a case; wherein the engagement includes at least one of the line side electrical contact and the respective load side electrical contact moving through an arcing zone to make an electrical connection; wherein the arcing zone includes at least one constriction zone adapted for limiting arcing between the respective electrical contacts. 
     In a further embodiment, a circuit interruption device is provided. The device includes at least one line side electrical contact and at least one respective load side electrical contact, the electrical contacts disposed within a case; each of the line side contacts configured for engagement with a respective load side contact, the engagement for electrically connecting an electrical supply with an electrical load; wherein the engagement includes at least one of the line side electrical contact and the respective load side electrical contact moving through an arcing zone to make an electrical connection; wherein the arcing zone includes an expansion zone proximate to a constriction zone, the constriction zone adapted for limiting arcing between the respective electrical contacts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention are apparent from the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is an isometric view of a circuit interruption device according to the teachings herein; 
         FIG. 2  is a cutaway isometric view of the circuit interruption device of  FIG. 1 ; 
         FIG. 3  is a cutaway isometric view of the circuit interruption device of  FIG. 1  and  FIG. 2 ; 
         FIGS. 4A through 4C , collectively referred to herein as  FIG. 4 , depict embodiments of a constrictive arc extinguishing feature; and, 
         FIG. 5A through 5B , collectively referred to herein as  FIG. 5 , are comparative illustrations depicting charge in a prior art device ( FIG. 5A ) and charge a circuit interruption device provided according to the teachings herein ( FIG. 5B ). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Disclosed herein is circuit interruption device with the constrictive arc extinguishing feature. The arc extinguishing feature provides for constriction of electric arcs that are generated during actuation of the circuit interruption device. Advantageously, the circuit interruption device disclosed herein provides for reductions in size and cost of manufacture. This results in savings to manufacturers and users and further provides for more versatile use of circuit interruption devices in general. 
     Referring now to  FIG. 1 , there is shown an exemplary circuit interruption device  10 . In this example, the circuit interruption device  10  may also be referred to as a “circuit breaker.” Although the teachings herein are introduced in the context of a circuit breaker, they may be applied in any circuit interruption device  10  where the techniques are deemed appropriate by a manufacturer, user, designer or other similarly interested party. That is, it should be noted that the circuit interruption device  10  is not limited to embodiments as disclosed herein, and may be used effectively in a variety of circuit interruption devices  10  as deemed appropriate. 
     In the exemplary embodiment, the circuit interruption device  10  is contained within a case  1 . The case  1  includes two components namely a first side  2 , and a second side  3 . Each of the first side  2  and the second side  3  are shown to contain a respective side of the case  1 . Of course, the circuit interruption device  10  may be of any shape deemed appropriate, and therefore the case  1  may include a plurality of components as deemed appropriate. For example, instead of the first side  2  and the second side  3 , the case  1  may include a top and the bottom; a bottom and a multi-part top, and any other similar construction as deemed appropriate. 
     Generally, the case  1  is constructed of any material deemed appropriate for the construction of a circuit interruption device  10 . Exemplary materials include hard plastics such as acrylonitrile butadiene styrene (ABS) and other materials such as fiberglass. Generally the case  1  is formed of materials that have a high dielectric constant, .di-elect cons..sub.r, over the range of temperatures and operating conditions that may be experienced by the circuit interruption device  10 . 
     The exemplary circuit interruption device  10  includes a handle  4 . The handle  4  is provided for manual resetting and actuation of the circuit interruption device  10 . The circuit interruption device  10  includes a line side connector  6  and a load side connector  5 . 
     Referring to  FIG. 2 , an isometric cutaway illustration of the circuit interruption device  10  of  FIG. 1  is provided. Current entering the circuit interruption device  10  enters through the line side connector  6  into magnetic coil  14  through and down to contact bar  7 . When the circuit interruption device  10  is configured to conduct the current, a movable contact  8  is engaged with a stationary contact  12 . The stationary contact  12  conducts the current to the load side connector  5 . When a load on the circuit interruption device  10  increases above a predetermined rating, a magnetic field generated by the magnetic coil  14  will cause the latch  15  to disengage, thus causing the circuit interruption device  10  to “un-latch” or “trip.” 
     Also shown in the embodiment of  FIG. 2 , is a gate  11 . In this example the gate  11  is movable. That is, the gate  11  may rotate about pivot point  20 . Rotation of the gate  11  is generally constrained by other features within the case  1 . For example, rotation of the gate  11  may be constrained by surface mounted features that are mounted on an interior surface of at least one of the first side  2  and the second side  3 . 
     Generally, the gate  11  is formed of materials that have a high dielectric constant, .di-elect cons..sub.r, over the range of temperatures and operating conditions that may be experienced by the circuit interruption device  10 . 
     In this exemplary embodiment, the circuit interruption device  10  includes an arcing zone  9 . The arcing zone  9  generally represents a volume where arcing between the movable contact  8  and the stationary contact  12  may occur during a tripping event. The volume of the arcing zone  9  is dependent upon a variety of factors. For example, as voltage or current traveling through the circuit interruption device  10  is increased, the arcing zone will likewise increase. 
     Note that the terminology “movable contact” and “stationary contact” are not limiting of the teachings herein. More specifically, as discussed herein, the movable contact  8  is with reference to a line side (i.e., a power supply) of the circuit interruption device  10 . As discussed herein, the stationary contact  12  is with reference to a load side (i.e., a connection with a power consuming device) of the circuit interruption device  10 . Accordingly, it should be considered that the terminology “movable contact” and “stationary contact” may be described by other similarly useful terminology such as with reference to electrical properties. 
     Consider now also  FIG. 3 , where another cutaway illustration of the circuit interruption device  10  of  FIGS. 1 and 2  is shown. In this example, the case  1  including the first side  2  and the second side  3  has been omitted from view. This omission is merely to enhance illustration and discussion of aspects of the circuit interruption device  10 . As may be seen from this angle the gate  11  includes a movable inner surface  17 . The movable inner surface  17  is configured to closely track or cooperate with the movable contact  8  as it is moved in relation to the stationary contact  12 . In this embodiment, an internal center case  18  is also provided. The center case  18  may present a stationary inner surface  19 . In this embodiment, the center case  18  also provides an insulative divider between a first movable contact  8  and a second movable contact  8 , such as in a double knife break circuit interruption device  10 . 
     In the embodiment shown in  FIGS. 2 and 3 , (referred to as “active” constriction), the gate  11  is configured to rotate about the pivot point  20  as the movable contact  8  rotates in relation to the stationary contact  20 . The geometry of the gate  11  is such that rotation causes the movable inner surface  17  to rotate towards the stationary inner surface  19 . As the movable inner surface  17  rotates towards the stationary inner surface  19 , an arc constriction zone is created within the arcing zone  9 . By constricting a portion of the arcing zone  9 , reductions in arcing are realized. That is, this provides for an increase in voltage capability without increase in package size of the circuit interruption device  10 . Alternatively, this design provides for smaller packaging of the circuit interruption device  10 . 
     Generally, the arcing zone  9  includes both an arc constriction zone (as introduced above), and a zone of relatively little constriction. Generally the zones of relatively little constriction reduce the likelihood that small conductive deposits (carbon, copper, and other conductive materials) formed during arcing will result in longer arcing gaps during arcing. Similarly, zones of relatively little constriction (also referred to as “un-constricted zones” or “expansion zones”) also allows the arc to expand and therefore allows the constriction zone to block out a larger percentage of the arc field, potentially reducing the arc extinguishing voltage. 
     Although one embodiment of the gate  11  is illustrated herein, this embodiment is merely illustrative and is not limiting of the teachings herein. For example, the gate  11  may include a plurality of moving components, cooperation of which result in the creation of the constriction zone. In general, the gate  11  may have a relatively constrained path that cooperates with the movable contact  8 . For example, the gate  11  may be configured in a push-pull arrangement, instead of about the pivot point  20 . (Embodiment not shown). Accordingly, it may be considered that the gate  11  moves in a “constrained path” of any type deemed appropriate in order to provide suitable constriction and expansion zones. 
     Referring now to  FIG. 4 , there are shown three exemplary embodiments of “inactive” constriction. In each of  FIGS. 4A, 4B and 4C , a segment of the first side  2  and the second side  3  are depicted. In each of these embodiments, the first side  2  and the second side  3  include symmetrically disposed and configured constriction features  19 . Together, the stationary inner surfaces  19  cooperate to form a constriction zone  41 . Complementing each constriction zone  41  is at least one expansion zone  42 . The movable contact  8  is configured to travel through each expansion zone  42  and constriction zone  41  before engaging the stationary contact  12  (not shown in  FIG. 4 ). As shown in  FIG. 4A , a cross-section of each of the first side  2  and the second side  3  shows that the constriction features  19  may be represented as in oblique right trapezoid, with a long side of the trapezoid facing the constriction zone  41 . In  FIG. 4B , a cross-section of the constriction features  19  shows that each of the constriction features  19  may be represented by a rectangle. In  FIG. 4C , a cross-section of each of the first side  2  and the second side  3  shows that the constriction features  19  may be represented as in oblique right trapezoid, with a short side of the trapezoid facing the constriction zone  41 . Generally, the embodiment of  FIG. 4A  provides better arc suppression and arc extinguishing as this arrangement interferes comparatively more with the electrical flux than the embodiments of  FIG. 4B , and  FIG. 4C . Of course, a cross-section of each of the constriction features  19  may be any one of a variety of geometric shapes. For example, a given constriction featured  19  may have a cross-section that is one of triangular, square, rectangular, irregular, patterned and the like. For example, in one embodiment, at least one of the constriction features may present a cross-section of a breaking wave. 
     Note that it is not a requirement that each of the stationary constriction features  19  are symmetric with respect to each other. Further, note that it is not necessary that the first side  2  and the second side  3  are used to provide the stationary constriction features  19 . For example, at least a portion of the stationary constriction features  19  may be provided by the center case  18 . 
     Referring now to  FIG. 5 , there are shown two illustrations of electrical flux within the circuit interruption device  10 . In  FIG. 5A , the expansion zone  42  essentially has room within the device for greater electrical flux (as arbitrarily depicted by lightning bolts). In contrast, as shown in  FIG. 5B , the constriction zone  41  has a reduced volume and therefore limits the electrical flux that may be transmitted (as depicted by fewer of the lightning bolts). 
     A variety of combinations of constriction zones  41  and expansion zones  42  may be had. Generally, the constriction zone  41  will follow the expansion zone  42  when considered in relation to a path of a closing contact bar  7 . However, a plurality of constriction zones  41  and expansion zones  42  may be used in any arrangement deemed appropriate. For example, multiple tightly spaced expansion zones  42  and constriction zones  41  may be incorporated into the circuit interruption device  10 . This embodiment may be referred to as including “arc grooves” due to the appearance of the tightly spaced zones. 
     In some embodiments, at least one expansion zone  42  may include a vent to the outer environment (not shown). 
     Having thus introduced and described various aspects of the circuit interruption device.  10 , some additional embodiments and other aspects are now discussed. 
     In general, it has been determined that the geometry of the entrance to the arcing zone  9  will influence the arc field. Generally, the arc field will be directed towards a lower pressure area of relatively little constriction, such as a vent. Additionally, a sharper or more acute entrance to the constriction zone  41  will discourage arc field organization and thus block out a larger percentage of the arc field, potentially reducing the arc extinguishing voltage. 
     Advantageously, this technology may be used in a variety of settings with a variety of devices. For example, use of arc constriction may be employed with higher break point devices (triple, quadruple, etc.), as well as a single break device. This may also be used with other circuit breaking devices such as, without limitation: switches, contactors, relays, disconnects, thermal circuit breakers, thermal-magnetic circuit breakers, toggle, push-pull buttons, push-push, automatic reset, and other similar devices. Arc constriction may also be used with AC or DC switching devices, including other (higher or lower) voltage rated circuits; a contact system that omits either the first un-constricted (i.e., expansion) zone or the second; a contact system that has more active constriction zone (e.g. biased flap, or compressed tube, that more completely constricts the arc). 
     Further, designs of the circuit interruption device that includes the constriction zone may consider and/or beneficially use arc constriction geometries to amplify the effects of the constriction (more acute arc constriction zone entrance); arc constriction geometries in combination with ablative materials; arc constriction geometries on devices other than knife contacts (button contacts, wiping contacts, etc.); arc constriction geometries on devices other than movable and stationary contact systems (e.g. where both contacts move away from a constriction zone). 
     Further, other aspects of the circuit interruption device may be configured with regards for the use of a constriction zone. For example, geometry of the constriction zone may be designed with consideration of the velocity at which the movable contact enters the constriction zone. Modifications to the knife contact system such as pinch force on the knife contact may be used. Further, arc constriction geometries may be used in devices with virtually any mechanism design (e.g. a more purely tease free contact closing designs). 
     Arc constriction geometries may be incorporated into devices with other arc mitigation element (arc grids, anti-arc tacking case features, arc shadows, arc horns, arc extenders, arc shields, insulation, etc.); arc constriction geometries may also be used in devices with arc grids (conductive, metal, etc.) in the constriction zone. 
     It should be recognized that the teachings herein are merely illustrative and are not limiting of the invention. Further, one skilled in the art will recognize that additional components, configurations, arrangements and the like may be realized while remaining within the scope of this invention. For example, configurations of sensors, circuitry and the like may be varied from embodiments disclosed herein. Generally, design and/or application of components of the redundant sensor is limited only by the needs of a system designer, manufacturer, operator and/or user and demands presented in any particular situation. 
     Various other components may be included and called upon for providing for aspects of the teachings herein. For example, additional materials, combinations of materials and/or omission of materials may be used to provide for added embodiments that are within the scope of the teachings herein. 
     When introducing elements of the present invention or the embodiment(s) thereof, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. Similarly, the adjective “another,” when used to introduce an element, is intended to mean one or more elements. The terms “including” and “having” are intended to be inclusive such that there may be additional elements other than the listed elements. 
     In the present application a variety of variables are described, including but not limited to components, conditions, and performance characteristics. It is to be understood that any combination of any of these variables can define an embodiment of the invention. For example, a combination of a particular material for the body, with a set of sensors, under a particular range of a given environmental condition, but the specific combination might not be expressly stated, is an embodiment of the invention. Other combinations of articles, components, conditions, and/or methods can also be specifically selected from among variables listed herein to define other embodiments, as would be apparent to those of ordinary skill in the art. 
     While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.