Abstract:
A precision location system for a circuit breaker utilizing a phase cassette concept is disclosed. A cover plate is mounted to at least one of a plurality of single-pole units having a circuit breaker operating mechanism positioned thereon. The cover plate is configured to precisely align an actuator precisely located on the cover with the circuit breaker operating mechanism. The actuator trips a latch of the operating mechanism, thereby tripping the entire circuit.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/536,360 filed on Mar. 27, 2000 now abandoned. 
    
    
     BACKGROUND OF INVENTION 
     The present invention relates to the interface between a circuit breaker operating mechanism and a multipole circuit breaker, and, more particularly, to the precision location of a trip actuator unit mounted on the cover unit and a circuit breaker operating mechanism to trip a multipole circuit breaker. 
     In a circuit breaker of a phase cassette concept, the functional relationship between the operating mechanism and the trip actuator unit is such that when the trip actuator unit indicates a trip signal, the actuator must interface with the mechanism at the trip latch to open the breaker. Tolerances in the system hinder this functional relationship. A precision relation must necessarily be established between the circuit breaker operating mechanism and the trip actuator unit. 
     In U.S. Pat. No. 5,281,776 entitled “Multipole Circuit Breaker With Single-Pole Units”, single-pole units of a general box-like parallelepipedic shape are arranged side-by-side and are linked by alignment rods extending perpendicularly through the opposing side faces of each box. Since the internal components of each single-pole unit are framed laterally with a small clearance by the opposing side faces and are free to move slightly in other directions to compensate for irregularities in manufacturing or positioning, a certain amount of tolerance buildup results. Excessive tolerance buildup may cause the inadequate performance of the circuit breaker. 
     In U.S. Pat. No. 5,581,219 entitled “Circuit Breaker”, the trip actuator unit is in the form of a cassette detachably mounted on a molded base, and the molded base is detachably mounted to a cover of a circuit breaker casing. The cover rests on the casing of the unit, and the trip actuator unit and other accessories are properly located on the breaker by being mounted in recesses formed in the cover. 
     Because a precision spatial relationship is required between the trip actuator unit and the breaker operating mechanism for the proper functioning of the circuit breaker, tolerances in the system must be minimized. In order to minimize these tolerances, clearances between parts are eliminated by bringing parts into physical contact with each other and by dimensioning the circuit breaker such that critical components have a direct spatial relationship with other critical components. 
     SUMMARY OF INVENTION 
     The above discussed and other drawbacks and deficiencies are overcome or alleviated by a precision location system for a circuit breaker utilizing a phase cassette concept. The precision location system is between an actuator accessory and an operating mechanism in the circuit breaker having a cover plate configured to receive the actuator accessory. The cover plate is further configured to receive the operating mechanism and is configured to align the actuator accessory with said operating mechanism when the actuator accessory and operating mechanism are received in said cover plate. 
     In an exemplary embodiment, the cover plate has a first protrusion depending therefrom, which contains an alignment groove configured to engage an alignment rod extending through a plurality of single-pole breaking units to align the same. The alignment groove may or may not conform to the outer shape of the alignment rod. A second protrusion containing an alignment groove may depend from the cover plate to engage the same alignment rod at a different point, thereby providing additional side-to-side securement of the cover plate on the alignment rod. In an alternate embodiment, the alignment grooves may snappingly engage the alignment rods. A location tab disposed on the actuator provides a means for precisely mounting the actuator on the cover plate, thereby precisely locating the trip actuator unit on the circuit breaker operating mechanism. 
     Because the operating mechanism and the actuator accessory are mounted on different components within the phase cassette system, a location system is preferably utilized to precisely define the relationships between all of the components involved. The location system thus allows for a closely toleranced relationship between the cassette and the trip actuator unit by utilizing at least one alignment rod extending laterally through breaking units within the phase cassette assembly. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is an exploded isometric view of the circuit breaker showing the precision location system, of the present invention; 
     FIG. 2 is an isometric view of an alignment groove, of the present invention; 
     FIG. 3 is an isometric view of an alternate embodiment of an alignment groove, of the present invention; and 
     FIG. 4 is a side elevated view of the circuit breaker showing the precision location system, of the present invention, fitted to an alignment rod. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a precision location system between an actuator accessory and a breaker operating mechanism is shown generally at  10 . Precision location system  10  comprises a phase cassette assembly  12  and an actuator (shown below with reference to FIG. 4) operably connected to a breaker operating mechanism  14 . Phase cassette assembly  12  comprises at least one breaker unit  16  housed in a base portion  18  having a mid-cover  20  securable to base portion  18 . A protrusion  36  having an alignment groove  22  depends from mid-cover  20  and engages a first alignment rod  24  inserted through breaker unit  16  and any adjacent breaker units  17 ,  19  and breaker operating mechanism  14 . Alignment groove  22  engaging alignment rod  24  precisely locates actuator and breaker operating mechanism  14  to ensure that breaker unit  16  and adjacent breaker units  17 ,  19  will be tripped when the appropriate signal is received. 
     To maintain proper alignment between breaker units  16 ,  17  housed within phase cassette assembly  12 , first alignment rod  24  and a second alignment rod  26  are inserted through holes  28  in the sides of breaker units  16 ,  17 ,  19 . First alignment rod  24  and second alignment rod  26 , when inserted laterally through breaker units  16 ,  17 ,  19 , prevent breaker units  16 ,  17 ,  19  from moving laterally relative to each other within phase cassette assembly  12 . 
     Protrusion  36  having alignment groove  22  depends from an edge of an underside  30  of mid-cover  20  and is dimensioned to fit between breaker units  16 ,  17 . In the preferred embodiment, a second protrusion (not shown) depends from an opposing edge of underside  30  to fit between breaker unit  16  and adjacent breaker unit  19 . First alignment rod  24  extending laterally through holes  28  in breaker unit  16  and adjacent breaker units  17 ,  19  is received by alignment groove  22 . The point at which first alignment rod  24  extends through breaker unit  16  is dimensioned from the centerline of an axis of a rotary contact arm (not shown) housed inside breaker unit  16 , which functions to break the circuit and interrupt the flow of current in the event an overcurrent occurs. In the final assembly, fasteners  32  are used to secure mid-cover  20  to base portion  18  and a top cover  34  to mid cover  20 . 
     Referring now to FIG. 2, protrusion is shown generally at  36  and in greater detail. Protrusion  36  depends from underside  30  of mid-cover  20  and includes alignment groove  22 . Alignment groove  22  is defined by a surface  38  that conforms to the outer cross sectional surface of first alignment rod  24 . As shown, surface  38  is rounded to engage an alignment rod having a circular cross section. When phase cassette  12  is fully assembled, first alignment rod  24  engages surface  38  and precisely locates mid-cover  20  on base portion  18 . In a preferred embodiment, protrusion  36  is integrally molded into an underside  30  of mid-cover  20 . 
     Alternately, an alignment groove may snappingly receive first alignment rod  24 . Referring now to FIG. 3, an alternate embodiment of protrusion is shown generally at  136 . In such a case, alignment groove  122  comprises two prongs  137  having inner surfaces  138  substantially conforming to an outer cross sectional surface of first alignment rod  24 . Typically, since alignment rod  24  is of a circular cross section, inner surfaces  138  of prongs  137  are arcuate. Prongs  137  are positioned to snappingly receive alignment rod  24  transversely with respect to phase cassette assembly  12 . 
     Each prong  137  protrudes substantially normally away from the general plane of mid-cover  20 . A protruding end of each prong  137  contains a generally rounded surface  140 , which facilitates the movement of prongs  137  around alignment rod  24  when mid-cover  20  is closed and alignment groove  122  is forced over alignment rod  24 . When prongs  137  of alignment groove  122  are forced to engage alignment rod  24 , rounded surfaces  140  force prongs  137  to flex away from each other. Once alignment rod  24  is more than half way into alignment groove  122 , rounded surfaces  140  close over alignment rod  24  and prongs  137  flex back toward each other to snappingly retain alignment rod  24  between prongs  137 . 
     Referring now to FIG. 4, alignment groove  22  is shown fitted over first alignment rod  24  to locate and align mid-cover  20  on phase cassette assembly  12 . The position of alignment groove  22  on mid-cover  20  is dimensioned from the center axis of rotary contact arm  56  housed inside breaker unit  16 . Rotary contact arm  56  includes a first contact  58  extending therefrom in switchable electrical contact with a second contact  60  (shown in phantom). A precision fit between the engagement surface of alignment groove  22  and first alignment rod  24  minimizes the tolerances between breaker units  16 ,  17  and breaker operating mechanism  14 , thereby avoiding tolerance buildup in precision location system  10 . 
     In precision location system  10 , a precision relationship is critical to system performance. Actuator  50  serves to trigger the breaker operating mechanism  14  and trip breaker unit  16 , thereby tripping adjacent breaker units  17 ,  19  and removing power to the circuit. Actuator  50  is mounted on mid-cover  20  and properly aligned thereon by means of an actuator location tab  52 . An accurate relationship between actuator location tab  52  and alignment groove  22  on mid-cover  20  is maintained. This, in conjunction with the precision fit between alignment groove  22  and first alignment rod  24 , aids in minimizing the tolerance accumulation between actuator  50  and operating mechanism  14 . Precision mounting of components ensures the minimization of tolerance accumulation and will ensure that all breaker units are tripped when a signal to do so is received. 
     While this invention has been described with reference to a preferred embodiment, 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 may be made to adapt a particular 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.