US 3321596 A
Description (OCR text may contain errors)
y 23, 1967 K. M. DELAFRANGE 3,321,596
PLUG CONNECTOR THERMALLY RESPONSIVE OVERLOAD CIRCUIT BREAKER Filed Dec. 21, 1965 \i zg I; ag! Q m 1] o o o o O O O o o o o o x/vz avmk 8y wgmw United States Patent Ofifice 3,321,596 Patented May 23, 1967 3,321,596 PLUG CONNECTOR THERMALLY RESPONSIVE OVERLOAD CIRCUIT BREAKER Kenneth M. Delafrange, 96 Washington Ave., Westwood, NJ. 07675 Filed Dec. 21, 1965, Ser. No. 515,405 Claims. (Cl. 2tl0116) This invention relates to improvements in thermally responsive overload electrical circuit breakers of the quick detachable plug-in type.
The invention has as its object provision of a simplified manual reset economical plug-in overload circuit breaker which may be installed and used permanently in substitution for fuses in new and old wiring systems, fuse boxes, circuit connector panels and the like, thus avoiding dangers attending fuse replacements, and also avoiding the troublesome necessity of keeping at hand a number of fuse replacements for restoration of service after a circiut fault correction.
Objectives of the invention are accomplished by a simple in line circuit breaker structure economical to manufacture, an emobdiment of which is hereinafter described and illustrated in the accompanying drawing wherein I FIG. 1 is a side view in elevation of an embodiment of the invention, the view being partly broken showing in cross section a circuit breaker latch and reset detail.
FIGURE 2 is a vertical median cross section on line 22 of FIG. 1 showing one of the counter part halves of the body structure of FIG. 1 and with the circuit breaker assembled therein.
FIG; 3 is a horizontal cross section of an assembled p ug body taken on line corresponding to line 33 of FIG. 2.
FIG. 4 is a median cross section view corresponding to that of FIG. 2 but showing a modified circuit breaker arrangement.
FIG. 5 is an end FIGS. one to three.
Having reference to FIGS. 1-3 of the drawing there is shown a screw shell type thermally responsive circuit breaker 1 comprising a conventional screw shell contact for detachable association with a screw shell socket surrounding an insulator plug body of abutting half portions 2 and 3, each portion being internally recessed and provided with countersunk holes therethrough adapted to register with holes in the counterpart portion and be fixed securely together by tubular rivets 4. The inner recess 5 in plug portions provide air ventilation for breaker units between inwardly directed ribs 6 and in the bottom recess portion provide expansion room and guide space for breaker elements. Ribs 6 centrally position the circuit breaker assembly and afford minimum frictional contact therewith.
Before jointure of plug portions, however, the circuit breaker assembly is installed within and between the plug portions. This circuit breaker mechanism includes a helical spring form high temperature nickel-chrominurn alloy conductor 7 fixed at one end to a conductor contact 8 seated in a receiving slot in the body portions and overlapping the plug end to constitute the center contact of the plug. While the conductor contact 8 may take other forms not shown, this element serves as firm anchor for one end of the spring form conductor 7. At its other or free end the helical conductor is fixed to and carries a movable contact bar 9 extending laterally in a bottom recess portion into overlapping contact with fixed contact 12 of connection 10 soldered at 11 to the lower edge portion of the screw shell contact. Thus in its normal state the circuit breaker is electric current plan view of the circuit breaker of conductive through center contact 8, spring form conductor 7, contact bar 9, contact 12, conductor 10 and its soldered connection with the screw shell contact.
Spring form conductor 7 is preferably of Nichrome wire predetermined as to gauge and extent to conduct electric current therethrough within a predetermined load consuming current value range without distortion of the conductor. The spring form conductor is lightly tensioned in its installation to effect positive overlapping pressure of contact bar 9 on fixed contact 12. Such constitutes normalcy of the breaker arrangement throughout normal predetermined safe current load range for which the breaker is designed.
The helical spring form conductor has a high coefficient of exapnsion so that on occurrence of overload current beyond that for which the breaker is designed the spring form conductor instantly overheats forcing linear expansion thereof to separate contact bar 9 from fixed contact 12 to break the circuit. In the normal reaction after having broken the circuit, the spring form conductor on cooling contracts to cause closure of the contacts and the circuit. However, this is prevented automatically by a spring loaded latch and reset member 14 having intermediate trunnion portions pivotedly mounted in mating recesses in the plug half portions, a hook form inner end portion in contact with the side of contact bar 9, a spring 15 forcing the latch into such contact and an outer finger tip operable lever portion normally housed, as to main body part, within a provided recess in the outer end of the plug body. The inner hook end of the latch and reset member at its contact with contact bar 9 is beveled or rounded for minimum frictional contact engagement with the bar and is provided with a lateral flange portion operable when the circuit breaker functions on overload to interpose its insulating body between the fixed and movable contacts preventing arcing and reclosure of the contacts and the circuit.
The latch and reset member being fixed as to position functions immediately on expansion of the spring form conductor to commence engagement behind the moving switch bar contributing to speed of contact separation by the pressure of the latch swinging into lock out position behind the bar. Simultaneously in this operation of the breaker the opposite end finger tip lever portion of the latch and reset member swings outwardly of its accommodating recess to resetting position. Sides of this lever end portion may be colored red or as desired to indicate to a user the breaker condition which is also shown of course by the swung down position of the lever. To reset the breaker after a circuit fault has been corrected it is only necessary to push the latch and reset lever end back into its recess against the spring tension thereon. This swings the latch out of its engagement behind the contact bar and its insulating and are prevention flange from between the contacts which close with snap action under tension of the cooled spring conductor.
FIG. 4 shows a modified structural arrangement wherein the breaker is substantially as previously described except that contact bar 9 has on its rear side thereof a thin ferrous armature backing strip 17, and, in lieu of the latch member an insulation slide 18 normally has an end portion in engagement with the side of the contact bar 9 and its side edge portions sl-id'ably mounted in guide recesses in the plug portions. An angular pivoted lever 19 has an inner end portion extending through an aperture in the insulating slide to eifect its slidable operations. Intermediate the lever end engaged through the slide and the fulcrum portion of the lever pivoted in recesses in the plug halves there is provided a ferrous armature 24 fixed to the lever and cooperative with a 22 below the contact bar at the bottom of the recess. This magnet is coextensive with the underlying armature strip 17 on the contact bar and has a beveled end portion defining greater extent of the magnet at the bottom than at the top. With the insulator slide retracted to its normal position by the lever the armature 24 is in close proximity with the permanent magnet at lower edge portions of the armature and magnet so that the armature is in the magnetic field to cause pivoting of the lever. End engagement of the insulator slide with the contact bar prevents this action until the circuit breaker operates under overload. When overload operation happens the contact bar quickly moves out of contact with the insulator slide end, the lever then swinging under influence of the permanent magnet to project the insulator slide in position between the fixed and movable contacts.
The other or outer end portion of the lever extends through a slot 23 in a manual reset button 21 headed at its inner end and extending through apertures in the permanent magnet and the plug end portion outwardly of the plug for reset operation.
The air gap between the permanent magnet and armature strip 17 is such that the armature remains affected by the permanent magnet but in a portion of the magnetic field wherein the greater forces of the tensioned spring form conductor overrides the permanent magnet force. When the circuit breaker is subjected to abnormal overload current and operates, the armature 17 moves closer to the ermanent magnet and into increasing power of its magnetic field. When the circuit breaker operates under overload conditions, however, its circuit breaking operation is enhanced by the magnetic pull. The circuit breaker is manually reset in this structure merely by finger pushing the reset button inwardly which retracts the insulator slide and forces the contact bar and its armature inwardly and away from the permanent magnet until overriding pull of the helical conductor is effective to close and hold closed the circuit contacts.
Having described the invention in connection with a preferred embodiment thereof, the words employed are those of description rather than of limitation as changes in structure and types of contacts are contemplated within the purview of the appended claims without departure from the true scope and spirit of the invention.
1. In an electrical plug connector thermally responsive overload circuit breaker, an insulating plug body having mounted thereon an external screw shell contact and permanent magnet internally recessed to receive, hold and position therein an overload circuit breaker assembly and provide operational space therefor, a fixed contact extending into said operational space and connected with said screw shell, circuit conductor means supported within the plug recess fixed at one end of the plug for circuit continuity therethrough from a conventional electric screw shell socket and provided at an inner free end with a contact member normally engaged with said fixed contact, said circuit conductor means directly including between the fixed end thereof and its. free end in circuit connection with said fixed contact a helical spring form conductor of nickel-chromium alloy composition and of predetermined size and conductive capacity, said helical spring form conductor normally maintaining ciated contact in conductive engagement with said fixed contact throughout a predetermined normal load current flow range but subject to linear expansion to separate the contacts and break the circuit continuity under heat generated in the helical conductor resultant from overload current flow above said range.
2. An overload circuit breaker as defined in claim 1 characterized by automatic means operable on separation of the contacts to prevent arcing and reclosing of the contacts until said means is manually operated to allow the contacts to reset.
3. An overload circuit breaker as defined in claim 1 characterized by automatic means comprising a pivoted spring loaded latch-lever preventing reclosing of the contacts separated as result of overload until the latch-lever is manually operated to release the latch to allow the contacts to reset.
4. A plug connector overload circuit breaker as defined in claim 1 characterized by a permanent magnet in the bottom recessed portion of the plug and an armature fixed to said helical free end contact member with an air gap between the magnet and armature which decreases in event of linear expansion of the helical conductor.
5. A circuit breaker structure as characterized by the plug body comprising two counterpart half portions interiorly recessed to accommodate and hold the circuit breaker and ing the half portions together.
No references cited.
BERNARD A. G'ILHEANY, Primary Examiner.
H. B. GILSON, Assistant Examiner.
its free end asso-- defined in claim 1' parts positioned byfasten-