Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Tripping means
Reexamination Certificate
1999-08-27
2001-05-01
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Tripping means
C335S035000
Reexamination Certificate
active
06225882
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to circuit interrupters generally and, more specifically, to those kinds of circuit interrupter having a trip mechanism including an automatic trip assembly for generating a magnetically-induced tripping operation.
2. Description of the Prior Art
Molded case circuit breakers and interrupters are well known in the art as exemplified by U.S. Pat. No. 4,503,408 issued Mar. 5, 1985, to Mrenna et al., and U.S. Pat. No. 5,910,760
issued Jun.
8, 1999 to Malingowski et al., each of which is assigned to the assignee of the present application and incorporated herein by reference.
A continuing industry objective with respect to many types of circuit interrupters is to be able to reduce the size and/or footprint of the interrupter housing while at the same time providing the same or improved performance capabilities. A major advantage of creating such a “smaller package” is that it provides increased flexibility in installation. However, a consequence of this objective is that the internal space constraints of such interrupters have become much more limiting, posing certain design obstacles that need to be overcome.
Circuit interrupters advantageously provide for automatic circuit interruption (opening of the contacts) when an overcurrent condition is determined to exist. One way of determining whether or not an overcurrent condition exists is to provide a trip mechanism with an automatic trip assembly that reacts to a magnetic field generated by the overcurrent condition. In such circuit interrupters, the reaction to the magnetic field is often in the form of a movement of an armature that, in turn, sets in motion a tripping operation.
In order to enable such movement of the armature, the prior art provides complicated structures which, unfortunately, occupy a relatively significant amount of internal space within the interrupter. It would be advantageous if a less complicated, more direct way existed by which to provide for movement of the armature and that could be effectively employed within circuit interrupters having the aforementioned space constraints. It would also be advantageous if such a way would enable the armature to easily be installed during the assembly process of the interrupter.
SUMMARY OF THE INVENTION
The present invention provides a circuit interrupter that meets all of the above-identified needs.
In accordance with the present invention, a circuit interrupter is provided which includes a housing, separable main contacts disposed in the housing, and an operating mechanism disposed in the housing and interconnected with the contacts. Also provided is a trip mechanism disposed in the housing and including a rotatable trip bar assembly that, when selectively rotated, generates a tripping operation that causes the operating mechanism to open the contacts. The trip mechanism further includes an automatic trip assembly for selectively rotating the trip bar assembly upon a predetermined current threshold. The automatic trip assembly includes a magnetic yoke having two arms with a pivot support on the top of each. Each of the pivot supports includes a pivot surface, and one of the pivot supports includes a rear retaining protrusion adjacent its pivot surface. The other of the pivot supports includes a front retaining member adjacent its pivot surface. The automatic trip assembly further includes an armature having pivot portions positioned on the pivot surfaces which provides for rotation of the armature between a first position away from the arms and a second position closer to the arms. A magnetic field is generated upon the predetermined current threshold which causes the armature to rotate from the first position to the second position and to rotate the trip bar assembly and generate the tripping operation.
A circuit interrupter is also provided which includes a housing, separable main contacts disposed in the housing, and an operating mechanism disposed in the housing and interconnected with the contacts. Also provided is a trip mechanism disposed in the housing and including a rotatable trip bar assembly that, when selectively rotated, generates a tripping operation that causes the operating mechanism to open the contacts. The trip mechanism further includes an automatic trip assembly for selectively rotating the trip bar assembly upon a predetermined current threshold. The automatic trip assembly includes a magnetic yoke having two arms with a pivot support on the top of each. One of the pivot supports includes a downwardly facing stop. The automatic trip assembly further includes an armature having pivot portions positioned on the pivot supports which provides for rotation of the armature between a first position away from the arms and a second position closer to the arms. The downwardly facing stop is positioned to abut the armature when the armature is rotated away from the arms, thereby defining the first position. A magnetic field is generated upon the predetermined current threshold which causes the armature to rotate from the first position to the second position and to rotate the trip bar assembly and generate the tripping operation.
This and other objects and advantages of the present invention will become apparent from a reading of the following description of the preferred embodiment taken in connection with the attached drawings.
REFERENCES:
patent: 2776349 (1957-01-01), Thomas
patent: 5250918 (1993-10-01), Edds et al.
patent: 5432491 (1995-07-01), Peter et al.
Gundy Raymond P.
Hood Teresa I.
Humbert Joseph B.
McNeil Michael
Peifer Jonathan M.
Donovan Lincoln
Eaton Corporation
Kosinski Charles E.
Nguyen Tuyen T.
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