US2496332A - Resettable circuit breaker - Google Patents

Description

Feb. 7, 1950 R. C-ARLE RESETTABLE CIRCUIT BREAKER 2 Sheets-Sheet 1 Filed April 6, 1948 w Vv7/// JNVENTOR. AE/VEAPLE' BY I WQK 91 & 2

Arrak/vay Feb. 7, 1950 R. CARLE RESETTABLE CIRCUIT BREAKER 2 Sheets-Sheet 2 Filed April 6, 1948 v 1 VENTOR. PEA E 6 ,2945

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Patented 7,

U NITED STATES PAT EN T OFF ICE RESETTABLEUIRCUIT BREAKER Ben Carlo; Brooklyn. N. Y;, assignor, bymesne assignments, to: Thermo Electric: Fuse Corps New'York; N. Y'., .a; corporation of; New York Application AprllTG; 1948, SieriaINo.,19;279j

ietoiaims (Cl. 200-116) This invention relates to resettable circuit;- breakers, particularly although not exclusively of the plug form type adapted for connectionin" ordinary line sockets.

'It is primarily within the contemplationofmy invention to provide a device of the above-men-- tioned category containing certain important" safety features in'addition' totheusual safeguard against injurious effectscaused'by short circuits: and current overloads. More-specifically; it is an object of my invention to provide, among others, the following twofeatures: (1) an arrangement of coacting electrical contactors'sep arate and independent from a thermal respon sive latching arrangement, and" ('2) anarrangement for preventing thecoacting electrical con tactors from being held' in circuit-closing"condi tion, except when the thermal-responsive; element isin its normal and non-deformed' 'eondis tion.

Itis alsoan object of this invention to' provide an additional safety' feature in circuit-breakers of the above-mentionedcategory whereby a there are no exposed openings'ormanually operable elements when thecircuit-breaker isinposition and when current is flowing'thereth-rough, so that the danger of'accidental contact witl'i-a-live conductor is eliminated.

Although many: attempts have been'made to provide circuit-breakers and-similar devices-with resettable. features, including certain oi the feaytures above-mentioned, thedevices have? gener: ally been intricate, delicate in structuregseasily upset; and difficult and" hence costly to 'manufao' ture. It is accordingly an important' o-iject of this invention to: eliminate the said shortcomings of other devices in the above-mentioned category; by providing a simple, rugged; as well as -eas operable device, capable ofperfcrm-ing theaforeal said functions and possessing-- the safety features above-mentioned.

Other objects, featuresrand;advantageswwtll arr-- pear from the drawings:.and-.'thedescriptlonrherea inafter given.

Referring, to the drawings Figure 1 is a vertical;.sectionscft;thezrcirou breaker of my invention shown in itszznormal e5 circuit-closing condition.

Figure 2 is a section of. Fig; vLtakem alongg'llnea 2-2.

Figure 3 isa viewlikeliig, 1', showing the;.the11"--- mal element in its retracted position andltheldemvice in its circuit-opening position.

Figure 4 is a longitudinal section; oft Rig... 3 taken along line. 4-4.,

Figure'5 is atopview of the'i'nner shellmember and both contact-carrying arms, looking downwardly from line 5-5, theouter'shellhav ing'been removed.

Figured is'a fragmentary schematic section'oi'; the device showing the parts in the normal circuit-closing positionof Fig. 1.

Figure 7 isa viewlike' Fig. 61' showingthedevice-in its circuit-opening"position; like" that of Figure 8 is a view siinilar toFig; '7, buts'howingr the; cooled iii-metallic" element partially curved and restrainedbytlieinner' shell walffrom assuming' its normarcurvedposition shown'by dot: dash lines, and

Figure 9'is a view like Fig. 8, showingthe def-- vice in the process of being reset; the'upper'contact element having been moved from the dot"- d'ash' position to the*uppermost position shown.

In the preferredform of' my'invention' illus'e trated in the drawings; the deviceis shownin the form of a" plug fuse consisting" of the outerf (or upper)" shell l0, which maybe made of plats-.- tie; Pyrex glassor other'insulator; the'inn'ers (orlower) pliigshell"! l which may: also' 'b e'made' of suitable'insulating'nraterialsuch as hot or'cold molded thermo-setting'plastic', the outer brass? screw shell l2 constituting' one fixed contact tierminal, the base contact" terminal" 13 extending through thelowerwall I In of-shell H"; the ther mal-responsive bi metallic [4* electrically and mechanicallyr eonnected to-the said-"terminal" I3, the lateraifispring branch ('or" lower contact arm) I 5 attaeh'ed to-ithe distalend lS o-f" the-strip M11 and carrying the insulator block l 'l at the bottom thereon and: the electrical contact ele' men-t 1| 8 omtheupper surface thereot; the upperspring, contact arm: r ta; electrically connected to: shell I2 and carrying on the undersurfaoe thereof the.-;eontact:,2;fl; audit 162 1365817.'pilii illlcomposediof insulating; materiahand; s li'dably movable; within channel; 22v of; inner: shell-,1 M. and against;v the: adjacent surface of theiouter :shell tea.

The-said, outer: shell .tflrha-s; a flat flange dsout'erza ,wall 23,; this wall being:exposed'to-vievwwhen: the plug, is)v operabl-p in.xplace;, the: wall in. thenpre ferred formtillustrated beingsolid a n'dt'containingv no openings zthereinrwhatsoeverr The; cylindrre cal. wall 2410f; shell l Ursurrounds thercylindricali wall: Hoof; the inner shell-1 I I" whichtzextendsxinto u thee-hollow interionof-E shell: I50; saidaeylindricalii wallv 25 being preferably, in slidablerengagementz with; the; interiors surface of i said; a wall 241. Thea; laterallyrextending annular: wall lfirofvthezsinnerr 55: shell. tl serveslaslalston;for the-innerr. annulanr' edge 21 of wall 24, thereby establishing the assembled relation between the outer and inner shells I and II, respectively. The said brass shell I3 is in threaded engagement with the outer surface of wall 24 of shell I0, and contains the annular base 28 underlying and in engagement with the lower surface of said wall 26, the arrangement hence serving to maintain the said inner and outer shells I8 and II in coactive assembled relation.

The said spring arm I9, which may be made of beryllium copper or some other suitable resilient conductor, extends from its free end transversely within the inner cavity of the device, is then sharply bent to form the longitudinally or downwardly extendin portion 29 disposed within recess 49 of wall and against the inner surface of wall 24, and then extends between the inner edge 21 of wall 24 and the abutting surface of wall 26 and upwardly along outer surface 0 of wall 24 into preferably soldered engagement with screw shell I2. The arrangement is hence such that the said spring arm I9 is physically held in position by having extended portions thereof clamped between the said inner and outer shells II] and II.

The bi-metallic strip I4 has its upper portion 30 normally curved inwardly towards the reset pin 2|, it being so designed that when an excess amount of current passes therethrough, it will straighten up, bending away from its said inclination towards the said reset pin. The reset pin 2| contains an intermediate ledge 3I disposed inwardly towards the cavity of the device, said ledge being adapted to engage the extended portion 32 of spring branch I5, in a manner to be hereinafter set forth. The reset pin also contains the upper ledge or terminal 33 with which the extended portion 34 of spring arm I9 is in constant yieldable engagement. The lower portion 35 of the reset pin extends downwardly below the recess 4! in the annular wall 26 and beyond the annular base 28 of the screw shell 20, the shoulder 36 thereof being abuttable with the inner surface of said base 28 to limit the downward movement of the reset pin. The said protruding portion 35 of the reset pin is manually engageable to impart a longitudinal sliding movement thereto, for purposes to be hereinafter set forth.

In the normal circuit-closing position of the device, contacts I8 and 28 are in engagement, and the insulating block I! rests upon the shelf 3! recessed downwardly from the upper edge 42 of the inner shell II. In this condition the electrical path is through the base contact terminal I3, the bi-metallic strip I4, the spring branch I5, the two contacts I8 and 20, the spring arm I9 and portion 29 thereof to the outer brass screw shel Upon a current overload condition, thesaid bi-metallic strip I4 will straighten out, causing upper portion 30 thereof to move to the left, away from the reset pin 2I, thereby retracting the insulating block II from its position on shelf 31, to cause said block to clear said shelf and the entire spring branch I5 to move downwardly. Since the spring branch I5 exerts a normal pressure downwardly, this retraction will cause a downward clicking action of the insulating block to the position shown in Fig. 7. In this position the contacts I8 and 20 have been separated, thereby breaking the circuit. However, due to the downward urging of spring arm I9, the reset pin will also be slidably moved downwardly until the said shoulder 36 engages the base 28. In this position, the extension 32 of spring branch I5 is disposed above the intermediate ledge 3|; and since the outer extension 34 of spring arm I9 is held against downward movement by the terminal 33 of the reset pin, the contacts I8 and 20 are maintained in a separated condition. It is important that when the device is in its tripped condition, as shown in Fig. 7, that ledge 3I be disposed below the said extension 32, the latter resting upon the said shelf 31 of the inner shell To reset the device into circuit-closing condition, the reset pin is pushed upwardly, whereupon the following action takes place in the sequence indicated: the terminal 33 of the reset pin first lifts extension 34, thereby raising the entire spring arm I9 to the position shown in Fig. 9; and in the course of this upward movement (after terminal 33 has engaged extension 34), the ledge 3I engages the extension 32 of the spring branch I5, causing it to move upwardly. However, since, upon a cooling of the bi-metalllc strip I4, portion 30 thereof has again assumed its normal curved shape, the raising of branch I5 beyond the level of shelf 31 will snap the insulating block I! over and in pressing engagement with said shelf. This action is enhanced by the fact that the curvature of portion 30 and its extension to a point above shelf 3'! causes a forward and downward pressure thereupon. Thereafter, upon a release of th reset pin 2I, and under the spring action of contact arm I9, contact 29 will engage contact I8, and will further press the insulating block II into engagement with said shelf 31. In this position the device is in circuit-closing condition, with the two contacts I8 and 2D in firm yieldable engagement.

It is to be noted that the arrangement above described makes it impossible to so manipulate the reset pin as to keep the two contacts I8 and 20 in engagement unless the insulating block I! rests on the shelf 21, and the device is in its intended trippable position. This must be so since before the intermediate ledge 3I can reach the extension 32 and lift spring branch I 5, it must first move the spring arm I8 upwardly, away from the position at which the two contacts I8 and 28 can come into engagement. In other words, when the terminal 33 and the ledge 3| of the reset pin are in simultaneous engagement with the extensions 34 and 32, respectively, finger 38 (the portion of the reset pin between ledge 3i and terminal 33) is deliberately made sufficiently long to keep the said two contacts I8 and 20 separated.

It should be further noted that since the reset pin-2I is located at the inner portion of the circuit-breaker, it becomes necessary to first remove the circuit-breaker from the wall receptacle in which it is housed in order to reset it. This provides a safety feature in that the only time a person need handle thedevice (except when removing the entire device from the receptacle) is when it is remote from any source of current.

It will be observed that the various objectives above mentioned, particularly the physical separation of the thermal-responsive latching elements from the electrical contact, and the resetting safety feature above described, are attained in a device having relatively few moving parts, and without the use of a combination of cams, levers and links such as are frequently found in other devices of this category.

In the above description, the invention has been disclosed merely by way of example and in. ilrefe'rred ma ner;- butobvicuslu many varies tions and modifications. maybeg-made therein which will still be comprised within its spirit. It is to beunderstood, therefore, that' the inventiqn lsrnot limit d to any specific form, or manner of practicing same, except insofar aswsuch-li'rnitar tions; are specified in the appended claims.

I claim:

1. In a resettable "circuit breaker, a hollow insulating body portion, two fixed electrically separated electrical terminals onthe fouter surface of said body portion, an internal shelf within said body portion, a reset pinfslidably mov able within said body portion and having a manually engageable portibnjejxtending outwardly "therefrom, said pin having, an intermediate I d'se "adjacent said shelf 'afn'd an upper ledge disposed "within said body "portion, a thermalresponsive strip connected to one of said "terminals and being normally bent towards said reset pin and being adapted to bend away therefrom under predetermined current overload conditions, a spring conductor branch extending from said strip and having on the undersurface thereof an insulating block adapted to rest upon said shelf when the strip is in said normally bent position and retracted therefrom when the strip is in its said overload condition, said branch containing an extension beyond said insulating block adapted to rest upon said shelf when the block is in said retracted position, the upper surface of said branch containing an electrical contact, a spring conductor arm electrically connected to the other of said terminals and positioned above said branch and containing on its undersurface a second electrical contact engageable with said first-mentioned contact when said insulating block is disposed on said shelf, said arm also containing an extension beyond its contact in yieldable pressing engagement with said upper ledge of the reset pin, said contacts bein separated when the spring branch extension is resting upon the said shelf, the said intermediate ledge being engageable with the said spring branch extension upon an upward movement of the reset pin to cause an operative resetting elevation of the said spring branch, the reset pin being movable under the action of said spring arm to a predetermined lower position when the block is in said retracted position.

2. In a resettable circuit breaker, the combination according to claim 1, the intermediate ledge of the reset pin being below and out of engagement with the said spring branch extension when th said reset pin is in its said predetermined lower position.

3. In a resettable circuit breaker, the combination according to claim 1, further provided with a stop member to limit th downward movement of the reset pin to said predetermined lower position, the intermediate ledge of the reset pin being blow the said shelf when it is in said lower position.

4. In a resettable circuit breaker, the combination according to claim 3, one of said fixed terminals being a screw shell in threaded engagement with the outer surface of said body portion, said screw shell containing an inwardly bent annular base engageable with the reset pin and constituting the said stop member.

5. In a resettable circuit breaker, the combination according to claim 4, the other of said fixed terminals being disposed in the lower part of the said body portion, the said thermal re- Sponsive strip being attached to said last-menshell containing an, annular wall engageablefwith th adia tm t on i heouter shell, said an.- nu arwa ont in ng, therei a rece the I'QSQt --Pi &V I a. her ion th reof x e ding;

through said recess.

9. In a resettable circuit breaker, the combination according to claim 1, the said body portion consisting of an outer shell and an inner shell in telescopic assembled relation, the said spring arm having an extension clamped between said inner and outer shells, the said shelfbeing a depressed portion of the upper edge of said inner shell.

10. In a resettable circuit breaker, the combination according to claim 1, the said reset pin being slidably disposed within an inner recess in the body portion, the upper terminal of said reset pin constituting said upper ledge.

11. In a resettable circuit breaker, the combination according to claim 1, the said body portion consisting of an outer shell and an inner shell in telescopic assembled relation, the said spring arm having an extension clamped between said inner and outer shells, said outer shell containing a solid top wall, the said reset pin extending downwardly beyond the bottom edge of the outer shell.

12. In a resettable circuit breaker, two adjacent movable contact arms bearing abuttable contacts, and a movable reset pin, said pin containing two ledges each engageable with one of said arms, the distance between said ledges being such that when both ledges are in simultaneous engagement with both arms, the contacts will be out of engagement; one of said arms being yieldably urged towards the other to bring said contacts into engagement, said reset pin being movable to urge one of the arms engaged thereby away from the other, whereby said contacts will be separated, said circuit breaker being further provided with a thermal-responsive element, one of said arms being connected to said element, a latch holding said arms with their said contacts in engagement, said thermal-responsive element being bendable under predetermined current overload conditions to disengage said latch from its said holding position, and spring means urging said thermal-connected arm away from the other arm.

13. In a resettable circuit breaker, one upper and one lower contactbearing arm, mutually engageable contacts on said arms, and a reset pin movable between upper and lower limiting positions, said pin containing two ledges, one above the other, the upper ledge being engageable with the upper arm and the lower ledge with the lower arm, the distance between said ledges being such that when both ledges are in simultaneous engagement with both arms, the contacts will be out of engagement, the upper of said arms being yieldably urged towards the lower to bring said contacts into engagement, said reset pin being movable towards its said upper limiting position whereby it will elevate the arm engaged by-the upper ledge and separate the upper contact from the lower contact, said lower arm being movable between an upper position where the contacts are in engagement to a lower position where they are out of engagement, the said lower ledge being adapted to engage said lower arm to elevate it to the said contact-engaging position, the upper arm yieldably bearing downwardly against the upper ledge of the reset pin to urge it towards its said lower limiting position, said circuit breaker being further provided with a thermal-responsive element, the lower of said arms being connected to said element, a latch holding said arms with their said contacts in engagement, said thermal-responsive element being bendable under predetermined current overload conditions to disengage said latch from its said holding position, and spring means urging said thermal-responsive-connected arm away from the other arm.

RENE CARLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 15 2,057,093 Geisslinger Oct. 13, 1936 2,147,754 Rivers Feb. 21, 1939 2,270,950 Jackson et a1 Jan. 2'7, 1942 2,293,382 Case Aug. 18, 1942

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