Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1994-10-24
2001-03-13
Echols, P. W. (Department: 3726)
Metal working
Method of mechanical manufacture
Electrical device making
C029S622000
Reexamination Certificate
active
06199264
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the class of electrical wiring devices known as ground fault interrupter (gfi) receptacles and, more specifically, to novel gfi receptacles suited for fully automated assembly, and to novel means for and methods of assembling and testing gfi receptacles.
Receptacles with circuit interrupting capability have come into wide-spread use in recent years, resulting in concerted efforts to reduce the cost of parts and labor required for their assembly while maintaining a high degree of operational reliability. Automated assembly techniques are widely used today to reduce labor costs, but at least some operations are still performed manually in virtually all commercially produced gfi receptacles.
Certain tests are performed upon gfi receptacles after complete assembly to ensure proper in-service operation. Some gfi receptacles have two or more housing sections which are mutually assembled by releasable connecting means and, following successful testing, are permanently connected, e.g., by heat fusion of opposing surfaces. Permanent connection of the plastic housing sections by mechanical means such as riveting, while providing certain advantages, add to assembly costs and are not generally employed in present-day gfi receptacles. Furthermore, in a currently conventional manner of fabrication of gfi receptacles, certain of the tests performed may not be entirely reliable for the intended purpose.
It is a principal object of the present invention to provide a gfi receptacle of novel design conducive to fully automated assembly.
Another object is to provide a novel, fully automated method of assembly of a gfi receptacle.
A further object is to provide a gfi receptacle having features which permit testing after complete assembly of all component parts, followed by either permanent assembly in a novel manner upon successful testing, or disassembly without damage to any components upon unsuccessful testing.
Still another object is to provide novel and advantageous means for and method of permanently connecting housing sections of a gfi receptacle, following complete assembly of all components, releasable coupling of the housing sections, and performance of all required tests.
A still further object is to provide a gfi receptacle including circuit components mounted on a printed circuit board having enhanced reliability of testing after assembly.
Yet another object is to provide a novel method of fabrication of a gfi circuit board which enhances the degree of reliability of tests designed to detect certain manufacturing defects.
Other objects will in part be obvious and in part appear hereinafter.
SUMMARY OF THE INVENTION
The gfi receptacle of the invention includes a plurality of components and subassemblies which may be placed in fully assembled relation by downward, vertical movement in a predetermined sequence. The parts are uniquely configured to permit assembly in this manner by fully automated means, thus eliminating costly manual assembly procedures. The configuration of parts and sequence of assembly also permit electrical connection of certain elements without otherwise required soldering.
Certain subassemblies and individual components are assembled, all by downward, vertical movement, with the printed circuit board after attachment thereto of surface-mount-device (SMD) electrical components. The SMD components include a pair of jumper cables which extend between respective pairs of electrical terminals on the board. One aspect of the assembly method includes breaking continuity of the usual circuit board traces connecting these pairs of terminals prior to surface mounting of the jumper cables on the board. As will be seen, this technique improves the reliability of operational testing of the gfi device.
Following the soldering operation, the circuit board and elements previously assembled therewith are moved vertically downward into the space defined by the rear housing section, the outer, rear surface of which rests on a horizontal support. After downward, vertical movement of several other elements into mutually assembled relation, the front housing section is moved downwardly, being guided into mating relation with the rear section by a plurality of posts on the front section which extend through openings in the rear section.
At termination of its downward movement the front section is releasably attached to the rear section by snap-fit detent means. The reset and test buttons are then assembled by downward, vertical movement into respective openings in the front housing section, and the required electrical tests are performed to ensure proper operation of the device. If any tests indicate unsatisfactory operation, the housing sections may be disengaged and the defective parts replaced or repaired. If the tests indicate proper operation, the housing sections are permanently joined by ultrasonic softening and physical deformation of the portions of the posts on the front section which protrude through the openings in the rear section. This has the effect of providing a mechanical-type, permanent connection of the housing sections, with the deformed ends of the posts being in the nature of rivet heads without requiring separate rivets and a conventional riveting operation.
REFERENCES:
patent: 3789268 (1974-01-01), Klein
patent: 4667263 (1987-05-01), Morris et al.
patent: 4686600 (1987-08-01), Morris et al.
patent: 4872081 (1989-10-01), Murphy et al.
patent: 4872087 (1989-10-01), Brant
Findley James K.
Finlay David A.
Marcou Jean-Claude
Murphy Patrick J.
Packard Thomas N.
Echols P. W.
Harter Secrest & Emery LLP
Pass & Seymour, Inc.
Salai Stephen B.
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