Abstract:
A circuit breaker includes a frame, at least one conductor supported by the frame, and a breaker mechanism supported by the frame and including a trip bar assembly that actuates the breaker mechanism. The circuit breaker also includes a magnetic armature assembly including an armature plate configured to move responsive to a current in the at least one conductor and an elongate link member (e.g., a rod) coupling the armature plate to the trip bar and having at least one flanged portion retained in at least one keyed slot in at least one of the armature plate and the trip bar assembly. The elongate link member may have a narrowed portion sized to allow passage of the link member through a narrowed portion of the at least one keyed slot to facilitate engagement of the at least one flanged portion in the at least one keyed slot.

Description:
BACKGROUND 
       [0001]    The inventive subject matter relates to circuit breakers and methods of fabricating the same and, more particularly, to circuit breakers with magnetic armature trip mechanisms and methods of fabricating the same. 
         [0002]    A circuit breaker may include a trip mechanism with a magnetically-actuated armature that is used to actuate a breaker mechanism that separates contacts in the breaker to interrupt a circuit. In some breakers, the armature includes an armature plate or similar structure that is displaced by a magnetic force generated by a current flowing through a conductor (e.g., a bus bar) magnetically linked to the armature plate. Movement of the armature plate causes a trip bar coupled thereto to rotate, causing the breaker mechanism to open the breaker contacts. 
         [0003]    In some breakers, the armature plate is coupled to the trip bar using a threaded rod running between the armature plate and the trip bar. It is desirable that this linkage be the proper length so that the breaker trips at a specified current level. Conventionally, this linkage is adjusted using hex nuts, stop nuts and/or other fasteners, which may complicate assembly of the breaker. For example,  FIG. 7  illustrates a armature plate  10  that is linked to a trip bar  20  using a threaded rod  30  with a retaining nut  40 .  FIG. 8  illustrates a similar armature link, except an e-clip  50  is used to retain the end of the link rod  30 . 
       SUMMARY 
       [0004]    Some embodiments of the inventive subject matter provide a circuit breaker including a frame, at least one conductor supported by the frame, and a breaker mechanism supported by the frame and including a trip bar assembly that actuates the breaker mechanism. The circuit breaker also includes a magnetic armature assembly including an armature plate configured to move responsive to a current in the at least one conductor and an elongate link member coupling the armature plate to the trip bar and having at least one flanged portion retained in at least one keyed slot in at least one of the armature plate and the trip bar assembly. The elongate link member may have a narrowed portion sized to allow passage of the link member through a narrowed portion of the at least one keyed slot to facilitate engagement of the at least one flanged portion in the at least one keyed slot. 
         [0005]    In some embodiments, the at least one keyed slot may include a first keyed slot in the armature plate and the at least one flanged portion may include a first flanged portion retained in the first keyed slot. The trip bar assembly may include a trip bar and a trip bar bracket attached to the trip bar, the at least one keyed slot may further include a second keyed slot in the trip bar bracket and the at least one flanged portion may further include a second flanged portion retained in the second keyed slot. 
         [0006]    In further embodiments, the elongate link member may include a rod and the at least one flanged portion may be positioned proximate an end of rod. The at least one flanged portion may include a first flanged portion proximate a first end of the rod and a second flanged portion proximate a second end of the rod. The first flanged portion may be retained in a first keyed slot in the armature plate. The trip bar assembly may include a trip bar and a trip bar bracket attached to the trip bar, and the second flanged portion may be retained in a second keyed slot in the trip bar bracket. The rod may have a narrowed portion sized to allow passage of the link member through narrowed portions of the first and second keyed slots. 
         [0007]    Some embodiments of the inventive subject matter provide a circuit breaker including a frame, at least one conductor supported by the frame and a breaker mechanism supported by the frame and including a trip bar and a trip bar bracket attached to the trip bar. The circuit breaker also includes a magnetic armature assembly supported by the frame and including an armature plate configured to move responsive to a current in the at least one conductor. The circuit breaker further includes a rod having a first flanged portion positioned at a first end thereof and retained in first keyed slot in the armature plate and a second flanged portion positioned at a second end of the rod and retained in a second keyed slot in the trip bar bracket. 
         [0008]    Still further embodiments provide methods of fabricating a circuit breaker. The methods include engaging a flanged portion of an elongate link member in a keyed slot in an armature plate of an armature mechanism of the circuit breaker and attaching the elongate member to a trip bar of the circuit breaker to thereby mechanically couple the armature plate and the trip bar. Engaging the flanged portion of the elongate link member in the keyed slot in the armature plate may include engaging a first flanged portion of the elongate link member in the keyed slot in the armature plate. Attaching the elongate link member to the trip bar may include engaging a second flanged portion of the elongate link member in a keyed slot in a trip bar bracket and attaching the trip bar bracket to the trip bar. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1 and 2  are different perspective views of a circuit breaker according to some embodiments of the inventive subject matter. 
           [0010]      FIGS. 3 and 4  are detailed perspective views of the circuit breaker of  FIGS. 1 and 2 . 
           [0011]      FIG. 5  is a plan view of an armature plate of the circuit breaker of  FIGS. 1-4 . 
           [0012]      FIG. 6  is a plan view of a trip bar bracket of the circuit breaker of  FIGS. 1-4 . 
           [0013]      FIGS. 7 and 8  illustrate conventional armature linkages. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Specific exemplary embodiments of the inventive subject matter now will be described with reference to the accompanying drawings. This inventive subject matter may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive subject matter to those skilled in the art. In the drawings, like numbers refer to like elements. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0015]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive subject matter. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0016]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0017]      FIGS. 1-4  are perspective views illustrating portions of a circuit breaker  100  according to some embodiments. Referring to  FIGS. 1 and 2 , the circuit breaker  100  includes a frame  100 , typically formed from a molded plastic material. Components supported by the frame  100  include a plurality of bus bar conductors  120  and a breaker mechanism  140 , which may be manually actuated using a handle  160  and automatically actuated by magnetic armature assemblies  130  mechanically coupled to a trip bar  142 . Each magnetic armature assembly  130  includes a spring-loaded armature plate  132  that is displaced by magnetic force generated by current passing through one of the bus bars  120  using flux linkage through an interposed magnet  137 . The armature plate  132  is mechanically coupled to the trip bar  142  by an elongate link member, here shown as a cylindrical rod  150 . 
         [0018]      FIGS. 3 and 4  provide detailed views of the armature plate  132 , trip bar  142  and linking rod  150 . As shown, the armature plate  132  has a first keyed slot  133  defined therein that retains a first flanged end portion  151  of the rod  150 . The rod  150  is mechanically coupled to the trip bar  142  using a trip bar bracket  144  having a second keyed slot  143  defined therein that retains a second flanged portion  153  of the rod  150 . As shown, the trip bar bracket  143  is attached to the trip bar  142  using a screw  146 , but it will be appreciated that other fasteners (releasable or non-releasable) may be used. As shown in  FIG. 3 , downward movement of the armature plate  132  due to magnetic force generated by current flow in the conductor  120  (and magnet  137 ) causes rotation of the trip bar  142 , which, in turn, causes the breaker mechanism  140  to operate and open contacts of the breaker  100 . 
         [0019]    Referring to  FIG. 4 , the link rod  150  includes a narrowed portion  155  (e.g., a groove) defined between the first and second flanged end portions  151 ,  153 . The narrowed portion  155  facilitates engagement of the rod  150  with the first and second keyed slots  133 ,  143  on the armature plate  132  and the trip bar bracket  144 . 
         [0020]    Referring to  FIG. 5 , which provides a plan view of the armature plate  132 , the first keyed slot  133  is open at an edge of the armature plate  132  and includes a narrowed portion  134  that is configured to allow lateral passage of the narrowed portion  155  of the rod  150 . Once the rod  150  is moved past this narrowed slot portion  134  and into an expanded portion  135 , the rod  150  may be slid longitudinally through the expanded portion  135  of the slot  133  until the first flanged portion  151  is brought into contact with the armature plate  132 . The enlarged portion  135  is sufficiently small to prevent passage of the first flanged portion  151  of the rod  150 , and thus retains the first flanged portion  151  in the armature plate  132 . 
         [0021]    Referring to  FIG. 6 , which provides a plan view of the trip bar bracket  144 , the second keyed slot  143  has a “dumbbell” shape including first and second enlarged portions  148 ,  149  connected by a narrowed portion  147 . The first enlarged portion  148  is sized to allow the second flanged portion  153  of the rod  150  to pass longitudinally therethrough. Once this end of the rod  150  is passed through the first enlarged portion  148  of the second keyed slot  143  and the rod slid through the first enlarge portion  148  of the second keyed slot  143  until the narrowed portion  155  of the rod is near the second keyed slot  143 , the narrowed portion  155  of the rod  150  may be passed laterally through the narrowed portion  147  of the second keyed slot  143  and into the second enlarged portion  149  of the second keyed slot  143 . The second enlarged portion  149  is sufficiently large to allow longitudinal movement of the rod  150  therein, while preventing longitudinal movement of the rod  150  past the second flanged portion  153 , thus retaining the second flanged portion  153  of the rod  150  in the trip bar bracket  144 . 
         [0022]    During fabrication of the circuit breaker  100 , installation of the rod  150  in the breaker  100  may occur as follows. With the trip bar bracket  144  initially detached from the trip bar  142 , i.e., with the screw  146  removed, the rod  150  may be first engaged with the keyed slot  133  of the armature plate  132  by passing the narrowed portion  155  of the rod  150  through the narrowed portion  134  of the first keyed slot  133  and into the enlarged portion  135  of the first keyed slot  133 . The rod  150  may then be moved longitudinally until the first flanged head  151  contacts the armature plate  132 . The trip bar bracket  144  may then be coupled to the rod in a similar manner. In particular, the second flanged head  153  of the rod  150  may be inserted through first enlarged portion  148  of the second keyed slot  143  and then trip bar bracket  144  moved along the rod  150  to the point at which the narrowed portion  155  of the rod  150  may laterally pass through the narrowed portion  147  of the second keyed slot  143 . The trip bar bracket  144  may then be moved along the rod  150  to the point at which the trip bar bracket  144  contacts the second flanged head  153  of the rod  150 . The trip bar bracket  144  may then be attached to the trip bar  142  using the screw  146 . Alternatively, the loose trip bar bracket  144  may be engaged with the rod  150  before engaging the rod  150  with the armature plate  132 , followed by fastening of the trip bar bracket  144  to the trip bar  142 . 
         [0023]    Armature linkages along the lines described above offer several advantages. Because the link rod (e.g., the rod  150 ) has a fixed separation between its flanged portions and may be manufactured to have a precise length within predetermined tolerances, link adjustment may be eliminated. In addition, the assembly process may be greatly simplified and use simple tools. 
         [0024]    It will be appreciated that the above-described structures and operations may be varied within the scope of the inventive subject matter. For example, although the illustrated embodiments illustrate an armature plate  132  having an open keyed slot  133 , it will be appreciated that other configurations may be used, such as a dumbbell-shaped slot similar to the one provided in the trip bar bracket  144 . While the illustrated embodiments use a link member in the form of a substantially straight rod  150 , it will be understood that some embodiments may use an elongate link member with a different configuration, such as rod with an offset bend. 
         [0025]    In the drawings and specification, there have been disclosed exemplary embodiments of the inventive subject matter. Although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the inventive subject matter being defined by the following claims.