US1328460A - Automatic circuit-breaker - Google Patents

Description

` x. D. SMITH; AUIOMATIC CIRCUIT BBEAKEB.

APPLICATION F'lLED SEPTi L Vl9l6. REIIEVIED- APR. -l0. 1919- n Patented Jan. 20,1920.

R. D. SMITH.

Auo'mulc cmcun samen. APPLICATION FILED SEPT. 7. I9l6. RENEWED APR. I0. I9l9.

1,328,460. Patentd Jan. 20,1920.

3 SHEETS-SHEET 2.

/0 w: l 9 v R. D. SMITH.

AUTOMATIC CIRCUIT BREAKER. APPLIcATloN FILED SEPT. 1. |9|6. Reuzwgn APR. I0. |919.

1,328Q460. I Patented Jan. 20, 1920.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

RAYMOND D. SMITILOF ARLINGTON, MASSACHUSETTS.

AUTOMATIC CIRCUIT-BREAKEB.

Speeioation of Letten Patent.

Patented Jan. zo, 1920.

Application led September 7, 1916, Serial No. 118,908. Renewed April 41t), 14H9. Serial 170.289,185.

To alliwhom z't may concern.'

Be it known that I, RAYMOND D. SMITH, a citizen of the United States,l residing at Arlington, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Automatic Circuit-Breakers, of which the followin is a specification.

y invention relates to delayed actlng, automatic circuit breakers and specifically to a circuit breakerfor use with currents of considerable magnitude wherein relatively heavy movable blades or their equivalents are sometimes used 'as current carriers, the construction which characterizes this type of circuit breaker usually being such that considerable friction opposes the movement of such blades in breaking the circuit.

The object' of my invention is therefore to provide an improved circuit breaker of the above cited type wherein upon suitable actuation of simple, convenient controlling means, (and preferably 'controllmg means lof conventional type such as are usually provided for the operation of a blade switch) a tension may be established tending, and suiiicient, to cause a desirably quick movement of the blades for breaking the circuit, but wherein such tension is normally opposed in its action to so break the circuit by a thermostatically controlled detent device, operative thermal energization of which (preferably through the agency of a thermally adjustable electric heating unit) is begun by the said actuation of the controlling means, and which after a predetermined time interval operates to release the switch blades and cause thereby an automatic and quick break of the circuit.

Other and specific objects of my present invention reside in the provision of auxiliary control instrumentahties, preferably associated in construction with the main controlling means above referred to, whereby,` at will, the said normally active detent device maybe manually rendered inoperative to hold the switch closed, which switch may then be manually operated in the usual man- 11er to make or break the circuit independent of automatic or other features present; in the provision of a thermally insulated, eleztric heating unit with eieientmeansfor the condhction of heat therefrom to the thermol stat; and further, in the compact and simple arrangement of the various operative art, and other details and improvements in switch construct-ion will also appear from the description and drawings hereof.

In the drawings z-Figure 1 is a detail view of the thermostatically controlled detent device taken partly in section on the planes 1--1 in Fig. 6; Fig. 2 shows a artial vertical section of the axially expanslble, thermostatic disk taken on the, axlal lplane 2-2 in Fig. 6; Fig. 3 is a right, side elevation of the entire circuit breaker showing the casing therefor in section; Fig. 4 is a front elevation of the thermost-atically controlled detent device and of the electric heating unit and' auxiliary switch therefor, taken partly in section on the vertical plane-4 4 in Fig. 1; Fig. 5 'is 4a front elevation of the circuit breaker with certain detent parts omitted for clearness; Fig. 6 is/a complete plan view of the circuit breaker, showing in sectional detail the construction of certain rheostat parts; Fig. 7 is a diagram of electrical connections; and Fig. 8, a view taken partly in section on the horizontal planes 8-8 in Fig. 3, shows more clearly and in detail the construction of the auxiliary heating circuit switch with its operative mechanical connections, and the pivotedconstruction of the rheostat lever.

I Throughout the, drawings and in the following description, similar and correspond- .ing parts are indicated by the same reference characters.

An insulating support panel usually constructed of slate, is shown at 1, and carries the conventional pole Contact clips 2 which are adapted to receive the swinging, conductive blades 3 pivoted each in a corresponding pole clip 4 at their opposite ends, the said blades being spaced and braced at their to by a connecting, non-conductive bar 5. Pivoted concentrically with the blades 3 is a swinging, frame 6 carrying a control handle 17 and connected to the blade structure by the two heavy, coiled springs 7, 7. The frame 6 is provided with bulfer clips 8, 8, to absorb the shock of contact when the sprin act to' open the circuit. A coinpoun bellcrank, pivoted detent lever 1s shown at 9 having a catch formatlon 10 at one end, normally positioned to engage with a.'spur projection 11 on the blade structure, and beingadjustably and positively engaged in one direction by the downwardly disposed arm 12 which carries at its end a roller 13 maintained in contact with the thermostat disk 14, by the spring 15.

The construction of this thermostat as shown in Fig. 2, comprises two annularly corrugated. andexpansible diaphragms `16 and 17 joined iuid tight at thelr periphery and filled with an expansible material sensible to changes in temperature. Reinforcing straps 18 prevent excessive axial expansion of the disk and afford means for conveniently mounting the same in surface contact with an upright, metallic, heatconduct ing strip 19. *y

Although the particular form of thermostat which I have shown for tripping the detent, namely an axially expanslble, liquidlled disk, is not essential to operativeness, and might be replaced by other equally powerful forms of thermostats, it will be ap-v preciated that the heretofore mentioned friction which must necessarily accompany a construction satisfactory for making and breaking largecurrents, renders necessary a relatively powerful spring means to produce a quick and positive break of the circuit, and that a detent device operative to oppose such spring means must be capable of producing an. appreciable amountof movement and of exerting sulicient force to overcome friction at the detent contact surfaces. I have found a disk form of thermostat lpreminently satisfactory for use in this connection both as to its power and .compactness and also becausevof the even degree of expansion which between the limits of movement may be made to vary nearly in direct proportion to the change in temperature. Y

'I-he asbestos layer 20 serves to thermally insulate the heat conducting strip 19. from the surrounding air as well as from the metallic supporting bracket 21. This heat conducting strip as shown best in Fig. 4, extends downwardly and is formed tightly around a horizontal copper tube 22, on which tube, separated therefrom by electrical insulating material, is a winding of resistance wire, designed to heat said tube suiciently to operatively raise the temperature of'the thermostat in the desired time interval. Insulating end supports 35 are provided at the ends of the tube, one carrying the winding terminal binding post 36 and the other, the winding terminal clip 33. v

A second, and wholly mechanical detentl lever is shown at 23, spring-,actuated to engage the swinging frame 6 in the position shown 1n Fig. 3, and to hold the same against the. tension of the springs 7 7. As will be ,evident from the drawings this detent may be disengaged at will by pressure upon the thumb button 24 seated in a socket at the end of the control handle 17.

An auxiliary switch is provided at one end of the resistance unit and is normally ositioned to break the circuit therethroug by the coiled spring 26 which spring acts on the plunger 28. As clearly shown in Fig. 3, the plunger is adapted to be actuated by the swinging frame 6 against the action of spring 26 to close the switch and to electrically energize the normally inactive heating unit, as will be clear from the diagram of connections in Fig. 7, where the corresponding symbols bear the same reference characters as the actual structural parts which they represent.

In Fig. 8 a detail of the auxiliary switch is shown wherein the conductive blade 30 is shown pivoted upon, and insulated from, the supporting spindle 31 of the heating spool, and which is provided with an insulated operating extension 32 connected in an obvious manner to the plunger 25j. The blade 30 engages with pole clips 33, 34. mounted upon the insulating end support 35 of the heating unit.

As evident from the diagram of connections and as also evident from the structure shown in the drawings, an adjustable rheostat is placed in series with the heating unit, this rheostat comprising a series of insulated spools 37, wound in series with resistance wire, and adapted individually to be put in series with the heating unit circuit to the extent of any selective number, by the rheostat arm 40. This arm is pivoted and provided with elctrical lconnections thereto, as shown at 41 in Fig. 8, and by means of a carried contact spring 42, bearing on the end of each spool in passing, operates in a well known way to vary the resistance and thereby the heat generated by the electric unit, and accordingly the time required to heat the thermostat. 4

The operation will have been obvious from the foregoing description. Closing the switch constitutes merely the pressure upon the thumb button and swinging of the handle and blades from the full line portion of the former and the broken line portion of the latter in Fig. 3 to the broken line position of the former and the full line position of the latter in the same ligure. 'Causing vdelayed opening of the switch constitutes lease the blade structure for movement with the frame 6, so that in sueh niannerthe switch may be manually opened without operation of delayed opening means.

B V a simple modification in the electrical connection of the rhcostat and electric heating unit itwill be apparent to those skilled in the art that the selfopcning switch herein illustrated could be adapted for use as a combined motor start-ing switch and automaticrcircuit breaker for protecting motors aud the like from excessive heating due to contimied overload. For such usc it'will be clear that the heating unit should be so connected in circuit that the current flowing therethrough shall be proportional to the line current. If desired, the three blade structure could be replaced by the usual double or single pole type of swinging contact arm. which arm could be arranged to cut out, by steps, starting resistance when approaching its circuit closing position, and which, uponbeing tensioned to open the circuit and locked by the thermostatically controlled detent against such tension, would act in an obvious manner to automatically guard against excessive and continued overloads to any predetermined degree.

An advantage resident in such use of my improved self opening switch as a protective circuit breaker is obviously that the circuit will be automatically broken through the agency of heat generated by the cur rent. `which heat will be directly proportioned to the heat caused by the excessive current iu the motor, regardless of the niagnitude of the, current which causes such heat. Thus differences in atmospheri(l temperature are allowed for and are equally effective on the protected' device and the automatic means for breaking the circuit. thc. said Imeans being therefore governed properly in accordance to the heating effect of the current, fromwhich it is desired to protect the motor, rather than -by the magnitude of the current as in various common types of electromagnetic protective circuitbreakers.

For use of my improved circuit-breaker as a protective device alone. it will be clear that the controlframe 6 may be permanently maintained in its position as shown in Fig. 3, and a control handle provided for actuating the blade structure directly; or that the control frame may be dispensed with and connection of the springs 7. 7, made to some rigid portion of the switch body, the auxiliary switch 30 in this case. being permanently closed.

Other applications of my present iiivention to the requirements of automatic circuit breakers will be obvious to those skilled in the art, and without, thfeiefore, limiting myself to the precise embodiment herein disclosed what I claim as new is:

1. An automatic circuitLbreaker embodying in combination with means for making and breaking a circuit; a manually operable actuating member arranged to be mov-l able relative .to said means and adapted when so moved to energize tensioning means tending to break the circuit; a detent device, with a controlling thermostat therefor, normally arranged and positioned to latch and hold said first means in a position to close the circuit against the opening action of said tensioning means; and a normally inactive heating. unit operatively related to the said thermostat and operably related to said member whereby the said thermostat may be thern'ially energized to'cause. a 1e lease of said means from restraint by 4said detent device.

2. An automatic circuit-'breaker embodying in combination with means therein for making and breakingr a circuit; a manually operable actuating member arranged to .be movable relative `to .said means; a resilient connection between said member and said means. arranged to oppose the relative movement thereof; an adjustable detent device positioned normally tolatchland hold the said first means. in its circuit closing position against movement with said member; a second detent arranged releasably yand automatically to lock the said member separated from said means against: the. act-ion of the said resilient connection; and a thermostat and normally inactive electric heating unit therefor, operatively related to the first detent device to cause a release therefrom of the Said first means; together withmcans governing the said electric heating unit and operably related to the said member, whereby the said heating unit may be operatively energized.

3. An automatic `circuit-breakerembodyv ing in combination with means therein for making and breakinga circuit; a separate member conceiitrically pivoted with said means having a handle extension for the manual actuation thereof; a resilient connection between said member and said means arranged to oppose'a relativemove ment thereof; a detent device positioned normally lto latch and hold the said first means in its circuit-closing position against movement with said member; a second detent arranged releasably and automatically to lock the said member separated from said means against the action of the said resilient connection; an operative extension structurally associated with the said handle extension and adapted b'y similar actuation4 thereof to release either the said means or the`said member from restraint by their said respective detents; .and a thermostat and normallyl inactive velectric heatin unit therefor, operatively related to the said first detent device to cause a release therefrom `of the said first means; and means governing the said electric heating unit and operably related to the'said member, whereby the said heating unit may be operatively energized. 4. An automatic circuit-breaker embodying in combination with means therein for making 'and breakin a circuit; avseparate member concentrica ly pivoted with said means having a handle extension for,the manual actuation thereof; a resilient connection between said member and said means arranged to oppose a relative movement thereof; a sprm actuated detent device positioned norma ly to latch and hold the said first means in 'its circuit-closing position by adjustable engagement therewith; a second sprin actuated detent arranged to automatically "l tensioned position relative to said means; an operative push rod structurally associated with the said handle extension and adapted by similar depressions` thereof to release both the said means and the said member from restraint by their respective detents; and an axially expansible thermo.- static disk operatively related to the said first detent device; together with a normally inactive, and structurally separate, electric heating unit and connecting heat conductor therefor, the said heating unit being operably related to said member and to a manu-l ally adjustable rheostat, whereby operative energization thereof is secured and controlled.

5. In anautomatic circuit breaker including means for making and breaking the circuit and automatic means'operatively associated therewith to move the said first means to break the circuit; in combination; a detent device normally operative to enge and hold the said first means against t 1e action of said automatic means; and a thermostatic disk adapted to be increased in axial thickness by the volumetric expansion of a contained Huid, and arranged and 'ositioned in operative ,relation to the sai detent device to move the same when thermally energized, thereby to cause release of the said first means.

6. In an automatic circuit breaker including means for making and breaking the circuit and automatic means operatively associated therewith to move the said first means.

to break the circuit; in combination; adetent device normally operative to engage and hold the said first means against the action of said automatic means; and an axially expansible thermostatic disk arran ed 1n operativeV relation to said detent devlce; to-

ock the said member in a.

ether with an electric heating unit arranged in operative connection to the main circuit and an operative thermal relation to the said thermostat and thereby adapted to energize the same for causing a release of the said first means. t

7 In an automatic circuit-breaker including means for making and breaking the circult and automatic means operatively associated therewith to move the said first means to break the circuit1 in combination; a detent device normally operative to engage and hold the said first means against the action of'said automatic means; and an axially expansible thermostatic disk arranged in operative relation to said detent device; to-

vgether with a normally inactive electric heating unit arra-nged in operative thermal relation to the said thermostat and thereby device; together with an electric heating unit comprising a metallic base carrying an insulated resistance winding with a heat conductive bonnection between said base and said thermostat, whereby operative thermal "energization of the thermostat for causing a releaseof the said first means is secured.

9. In an automatic circuit-breaker including means for making and breaking the circuit and automatic means operatively associated therewith to move the said first means to break the circuit, in combination; a-detent normally operative to engage and hold the -said first means against the action of said automatic means; and an expansible thermostatic disk with an operatively associated heatingv unit therefor; together with manually adjustable means, operatively relatedto the said heating u-nit and adapted to regulate the operative delivery of heat to the thermostat.

10. In an automatic circuit-breaker including means for making and breaking the circuit and automatic means operativelyassociated therewith to move the said first means to break the circuit, in combination; a detent device 4normally operative to en gage and hold the said first means against the action of said automatic means; and an axially expansible thcrmostatic disk with an operatively associated electric heating unit therefor; together. with a variable resistance device connected in circuit with the said heat to sai heater unit and adapted by manual adjustment tore late the operative delivery of thermostat.

11. An electric circuit lbreaker vhavin manually operable means for making an breaking the circuit and embodying in com- -bination' with-said means; a structurally separate actuating member therefor h aving a normally tensioned resilient connection to said means adapted to resist 'movement of the said actuating member relative to said means; a detent dci-icc arranged and positioned normally to latch and hold the said means in a position to closel the circuit; a

second detent arranged and positioned au-' 4tomatically to'catch and hold the said actuating member separated from said means against the action of said resilient connection therebetween and a thermostat adapted upon thermal energization thereof to move the vsaid detent device to release said means thereby to open the circuit; together with an electrically resistive heating unit arranged when energized to heat the thermostat, and an auxiliar abl related to the sald actuating extension an arranged to control the circuit through said heating unit.

12. An electric ,circuit breaker having manually operable means for makingand breaking the circuit and embodying in combination with said means; a structually separate actuating member therefor with -normally tensioned resilient connection to said means adapted to resist movement of the said actuating member relative to said means; a detent device arranged and positioned normally to latch and hold the said means in a position to close the circuit; a second detent arranged and positioned automatically to catch and hold the said actuating member separated from said means against the action of said resilient connection therebetween; a thermostat adapted upon thermal energization thereof to move the said detent device to release said means and open the circuit; an electrically resistive heating unit arranged when energized to heatl the thermostat; 'and' an auxiliary switch device operably related to the saidactuating extension and arranged to control the circuit through said heating unit; together with a manually adjustable device operatively associated with the said heat- 'ing u-nit whereby the rate of heat deliver to the thermostat may be varied.

13. An electric circuit breaker havin manually opera-ble means for making an breaking the circuit and embodying in com- A binat-ion with said means; a structurally separate actuating member therefor, with normally tensioned resilient connectionto said means adapted to resist movement of the said actuating member relative to said means; a detent device arranged and positioned norswitch device opercatch and holdthe said actuating memberv sefparated from said means against the action said resilient connection therebetween; manually operable instrumentalities structurally associated with the said actuating member and arranged upon suitable actuation thereof in one position of the said member to release the said means from the-said detent device, and upon similar actuation thereof in another position of said member to release the said member from the said second detent; and a thermostat adapted upon thermal energization thereof to move the said detent device to release said means and open the circuit; together with an electrically resistive heating Aunit arranged when yenergized to heat the thermostat, and anauxiliary switch device operably related to the said actuating extension and arranged to control the circuit through said heating unit.

14. An electricl circuit breaker havin manually operable means for making and 0breaking the circuit and embodying in combination with said means; a structurally separate actuatmg member therefor with normally tensioned resilient ,connection to saidv means adapted' to resist movement of the said actuatmgl member relative to said means; a detent device arran ed and positioned normally to latch and old the said said actuating extension and arranged to control the circuit throu h said heating unit. 15. In combination wlth a delayed acting automatic circuit breaker having manuall operable, normally denergized, automatically acting means for breaking the circuit, the said means, including a-releasable detent device normally positioned to maintain the circuit closed; a thermostatic disk adapted for thermally caused, axial ex ansion, operatively related to said detent evice to release the latter by said ex ansion; an electrically and thermallyinsuiated heating unit comprising a tubular, metallic bod wound withelectricalli resistive wire insulated therefrom, and aving a metallic, heat-conductnig portlon extending" therefrom vand terminatin in surface Icontact with the thermostatic disk, all substantially as shown and described.

- 16. In combination with a delayed actin automatic circuit breaker having manual y A operable, normally. dener ized, automatically acting means for brea mg'the circult, Athe said means including la releasable detent device normally positioned to maintain the `circuit closed; a thermostat and electrical heating unit therefor arranged when energized to cause the release of said detentv device; and a switch device, normally arranged to open the circuit through said electrical' `u'nit but operatively related to said Vmanual1y operable means thereby to be ac- 't'uajted to close lthe circuit when said automatically acting means are manually ener- -latory contact member; an osclllatory` actuator element inunted to swin J 17. An electric switch embodying an oscilwith and positively to im lsaid member 1n one direction oits os'cl ation and further arranged tive displacement of said element tensions ,A

said member for'ollow-'up .movement .from a circuit making to a ,circuit .breaking position; a detent arranged 'to prevent said follow-up 'movement of said, member when said element is displaced therefrom; means I to hold said member so displaced; and normall y inactive, slow acting, `in.st :rurnentalities arranged to be operatively energized by said displacement of saidelement, -and' thereby j rendered active to freesaid member from said detent after a predetermined interval of time.

Signed atl Boston, Masachusetts, this lsixth day of Septemberz' .RAYMQND D. SMITH Witnesses:I

- J;LANIGAN,, JAMES D. GoRnoN.y

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