US1632420A - Thermal circuit breaker - Google Patents

Description

a F. sMAFzT THERMAL CIRCUIT BREAKER June 14, 319270 Filed July 31, 1923 2 Sheeis-Sheec F. S MART June THERMAL C IRCUI T BREAKER Filed July 51,

Patented June 14, 1927.

UNITED STATES 1,632,420 PATENT OFFICE.

JOSEPH F. SMART, OF NEW BRITAIN, CONNECTICUT ASSIGNOR TO LANDEfis, FBARY d:

CLARK, OF NEW BRITAIN, CQNNECTICUT, A CORPORATION OF CONNECTICUT.

THERMAL CIRCUIT BREAKER.

Application filed J'uly 31, 1923. Serial No. 654,890.

heated utensil as it approaches a dangerous degree of heat, the aim of the invention being to provide a device of this sort having features of novelty andv advantage.

More particularly, the object of the inven-- tion is to provide a circuit breaker of this sort which 15 very sensitlve 1n operation in that it will break the circuit with surety when the temperature of the utensil, wit which it is associated, rises to within very small limits of the temperature at which the device is adjusted; which may be reset a very short time after the device has. been automatically operated; which may be adjusted with nicety to operate at any predetermined temperature above which it-is dangerous to heat the utensil; which is compact and economical in construction and which is housed within the utensil so it does not detract from the appearance of the utensil and so that it cannot be injured nor readily tampered with; and which may be manipulated 2 or set in a ready manner without removing any parts or disassembling the utensil.

Other ob'ects' of the invention will be part obviousan 'in part pointed out more particularly hereinafter.

In the accompanying drawings:

Figure 1 is a top plan view of an electrically heated utensil, for instance a sad iron, in which is embodied one form of my invention, the cover of the iron being removed for purposes of clearness, and the parts of my circuit breaker being illustrated in latched or on position;

Fig. 2 is a side view of the sad iron looking in the direction of the arrow 2 of Figure 1 and with the casing of the iron in central longitudinal section;

Fig. 3 is a view similar to Figure 1 but with the parts of the circuit breaker shown in unlatched or of! sition;

Fig. 4 is an enlarge sectional view, taken substantially on line 4-4 of Fig. 3; and

Fig. 5 is a fragmentary view, in top plan, of a portion of the handle of the sad iron with the setting lever of the circuit breaker positioned therebeneath.

In the drawings, I have shown my device applied to a sad iron, but it is to be understood that my invention is applicable for use generally on electircally heated utensils, the present disclosure being by way of illustration only and, therefore, it is not to be taken as restrictive of my conception.

Referring to the drawmgs in detail, a denotes the sole plate of the iron; I), a solid vmetal top plate; and c, an electrical heating element of any suitable construction posi-. late and the top tioned between the sole plate and insulated there rom. .ie is a sheet metal cover or casing which encloses the top "plate, the heating unit, and the thermo- ,'static device or cut-out of the present invention; and k is a handle suitably held in plaice pn the casing as by means of screws or The thermostatic device of the resent invention includes a circuit closer aving, in the present instance, a pivoted plate 10 resiliently carrying a circuit closing element 11 adapted to en age, and thereby close the circuit between, t e contact members 12 and 12' interposed in one of the leads of the heating unit 0; a thermostat 9 arranged to hold the circuit closer in circuit closing position until the utensil reaches a predetermined heat, resulting in the thermostat being flexed and disengaged from the circuit closer whereupon the latter will be thrown into off position breaking the circuit through the electrical heating unit; and the setting device or lever 13 sitioned on the outside of the casing and a apted to be manually operated to place the circuit-closer in on position after the iron has cooled suficiently to permit the thermostat to hold the circuit closer in this position.

The thermostat 9 comprises a pair of bimetal bars 14 and 15 each secured at one end to a U-shaped sheet metal plate 16 pivoted for rotary movement on the top plate by means of a screw 17. Fixed to one end of one of the bi-metal bars, in the present position, as hereinafter described more in etail. The thermostat .9 is normally urged in a direction togenga'gethe roller'18 with the, circuit closer, by means of a s ring 20 ositioned about 'thescrew 17. The other i-metal bar 15 is arranged to flex in a di-,

which stop is, by preference, adjustable so 1s, of course, understood that each of the bimetal bars is composed of two strips of metal having different co-efiicients of expansion and welded or otherwise secured together. In the present illustrative disclosure, the strips of metal having a lesser coeflicient of expansion are positioned on the outside of those strips which have a great co-eflicient of expansion. p

The latch plate 10 is pivotally on the top plate by a screw 23 and is normally urged by a spring 24 in a counterclockwise direction, referring to Fig. 1, that is in a direction in which the circuit closing element 11 is moved away from the contacts 12, 12. The latch plate 10 is provided with a depending tongue 26 to which is secured, by means of a spring 27, the circuit closing element or contact blade 11. The contact blade is, of course, suitably insulated from the latch plate. The latch plate is further provided with a shoulder or stop 30 against which the anti-friction roller 19 is adapted to engage and thereby hold the circuit closer in latched or on position.

Fixed to the to plate b, as-by means of one of \the nuts is a supporting bracket 34 on the up-turned portion of which the contacts 12 and 12 are secured, these members, however, being insulated from the supporting bracket. The contact member '12 is electrically connected to oneiend of the heating element or unit 0 by a stri 35. The opposite end of the heating unit is directly connected to a terminal post by a strip 37, and the contact member 12 is connected by a strip 38 to the other terminal post 36. It will thus be seen that the current will normally flow through one of the terminal posts, strip 37, the electrical heating unit 0, the strip 35, contact 12, circuit closing element 11, contact 12, strip 38, and the other terminal 0st 36 connected with the last mentioned strip.

For the purpose of re-setting or re-latching the circuit breaker, there is provided on the top of the cover e and beneath the strap or bail h of the handle a setting lever 13 connected to the cover. e by means of a pin 41 fixed to the cover and engaging in an elongated slot 42 in the lever. The lever 13 has an upwardly extending projection or lip 43 by means of which the lever may be thrown, and this rojection. or lip normally lies close to the side of the handle strap 72., where it is out of the way. It will be seen, particularly from Fig. 2, that the casing is provided with beads 44 upon which the nandle bail rests, and there is thus provided between the handle bail and the casing a mountedspace for the lever 13. Carried by the latch plate 10 and extending through an arcuate elongated opening 45 in the casing e is a pin or stud 46 to the upper end of which the lever 13 is pivotally connected. The lever 13 has a thickened boss '47 for'receiving this pin, and the strap h is offset upwardly as at 48 to accommodate this boss.

The operation of the device is briefly as follows. Assuming that the parts of the circuit breaker are in latched or on position, as shown in Fig.1, so that the current is flowing through the heating unit; when the temperature of the utensil gradually rises, the bi-metal bars 14 and 15 are flexed or bowed in opposite directions. Since the shoulder 30 of the latch plate is urged against the anti-friction roller 19 carried by the bar 14, this bar bends at its intermediate portion towards the center of the iron, causing the plate 16, to which the parts are secured, to turn slightly in a clockwise direction. Owing to this turning movement of the plate 16 and the flexure of the bar 15, the freeend of the latter, when the predetermined temperature is reached, at which the device is set to operate, engages the adjustable stop 21 whereupon the antifriction roller 19 will'be disengaged from the latch plate permitting the latter, under the influence of the spring 24, to rotate in a direction to withdraw the circuit closing-element 11 out of engagement with the contacts 12 and 12, thereby breaking the circuit through the heating unit. The parts will now assume the position shown in Fig. 3. It will be observed that the two thermostatic bars, when heated, are flexed in opposite directions and the arrangement is such that the flexure or movement of both of these bars is-combined or aggregated to release the circuit breaker. The thermostatic bars are placed side by side so that they take but a relatively small amount of space. Thus, there is provided an arrangement which, while extremely compact, has a thermostatic device of sufiicient capacity and size to operate positively and sensitively at any desired predetermined temperature at which the device may be set to throw the current ofi. Owing to the provision of the anti-friction roller 19, friction between the thermostat and the latch plate is reduced to a minimum. The roller will readily ride out of engagement with the latch plate when the thermostat has been flexed to a predetermined extent, and sticking of the parts is practically eliminated.

One of the advantages of the arrangement illustrated and described is that the circuit breaker may be re-set into circuit closing position a very short time after the breaker is operated to break the circuit; that is to say, the operator of the iron need allow but a very little time for the iron to cool slightly before he can again throw the current onto the heating unit, this being due to the fact that the thermostatic bars simultaneously flex back towards each other upon being.

.When the lever is in final position, the lip 43 lies closely to the bail so that it is out of the way and causes no annoyance or inconvenience. It will be understood that when the lever is thus pushed to re-set the device, the lever is fulcrul'ned against the pin 41' and moves, through the pin 46, the latch plate to t-he'position shown in Fig.1. All of the parts of the circuit breaker are enclosed within the casing and are thus protected and do not in any way mar the appearance of the iron. The lever 13 is so positioned that it is practically out of sight.

I claim as my invention:

1. A thermal circuit breaker including a circuit closer, and thermostatic means normally holding said closer in circuit closing position, said means including a plurality of thermostats, one of which is arranged to normally hold said closer in circuit closing posicuit closing position, an

static member arranged to move said pivoted tion and the other of which is arranged to move said first thermostat, said thermostats being so arranged that their responses to temperature changes are combined to efl'ect release of the closer.

2. A thermal circuit breaker including a circuit closer, a pivoted member, a thermostatic member carried by said pivoted member and normally holdin said closer in cir-- a second thermomember and thermostatic member carried thereby.

3. A thermal circuit breaker including a circuit closer, a pivoted member, and thermostatic means normally holding said circuit closer in circuit closing position, said means comprising a pjluralit of thermostatic elements carried y sai pivoted member and so arranged that their responses to temperature changes are combined to effect release of said closer. I

4. A thermal circuit breaker including a circuit closer, thermostatic means normally holding said closer in circuit closing position, said means comprising a plurai thermostatic elements movable in opposite directions upon temperature changes and so asranged that their responses to tem erature iiihan esare combined to effect re ease of said c oser, and adjustable means for regulating the operation of said thermostatic means.

5. A thermalcircuit b ty of.

' Tker including a circuit closer, means normally urging the same into open position, a pivoted member, and a pair of thermostatic bars carried by said pivoted member and arranged to normally hold said closer in circuit closing position. i

7 A thermal circuit breaker including a circuit closer, an abutment, and a pair of thermostatic bars placed side by side and adapted to flex in opposite directions, one of said bars being engageable with said circuit closer to hold the same in circuit closing position, and the other of said bars being operatively connectedto and movable with said first bar and adapted to engage said abutment and thereupon move said first bar.

thermal circuit breaker including acircult closer, means normally urging the 8. A thermal circuit breaker including a engageable with said circuit closer an when flexed under heat changes, adapted to move the other or second of said bars towards said abutment, and said second bar.

being adapted to en age said abutment and therebyrmove said rst bar out of engagement with said closer.

10. A thermal circuit breaker including a pair of contacts, a circuit closer having a latch plate pivoted at one side and a circuitclosing element resiliently connected to said plate and adapted to engage said contacts, a spring associated with said plate for normally urging the same ina direction to withdraw said element from said contact-s,

said plate'havin at the side opposite the pivotal point, a s oulder, a thermostatic bar flexible 1n the plane of said plate and adapted to engage said shoulder, and means for moving said circuit closer into circuit closing position. i t

11. A thermal circuit breaker for electrically heated utensils, including a supporting plate, a cover housing said sup orting plate, a pair of contacts, a circuit 0 oser having a latch plate pivoted to said sup porting plate and located beneath said cover, said closer further. includin a circuit closing element carried by said latch plate, thermostatic means carried by said supporting plate and arranged to hold said closerin circuit closing position, and pivoted means for re-setting said latch plate in circuit closing position connected to said latch plate and extending through an arcuate slot in said cover.

12. A thermal circuit breaker for electrically heated utensils, including a supporting plate, a cover housing said plate, a pair of contacts, a circuit closer having a latch plate pivoted to said supporting late and located geneath said cover, said 0 o'ser further inclu ing a circuit closing element carried by said latch plate, thermostatic means carried by said supporting plate and arranged to hold said closer in circuit clos- -ing position, a lever resting on the outside of said cover, a stud pivotally connecting said lever to said latch late, and a pin connecting said lever to said-cover, said cover having an arcuate slot to accommodate said stud and said lever having a slot to accommodate said pin.

13. A thermal circuit breaker for electrically heated utensils, including a supporting plate, a cover therefor, a strap connected to said cover, a circuit closer beneath said cover, thermostatic means for normally holding said closer in circuit closing position, and a lever positioned between said'strap and cover. and operatively connected to said circuit closer for re-setting the latter in circuit closing position.

14. A thermal circuit breaker for elccv ing lip adapted to lie closely against said strap when the lever is in its normal posi tion.

JOSEPH F. SMART.

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