US1271558A - Thermostatic time cut-out. - Google Patents

Description

J. C. FRANCIS.

THERMOSTATIC TIME CUT-OUT.

APPLICATION FILED JUNE I6. 1915.

Patented July 9, 1918.

ATTys.

UNITED-straws PATENT OFFICE.

JOHN C. FRANCIS, OF BOSTON, MASSACHUSETTS, ASSIGNOR T0 SAMSON ELECTRIC COM= PANY, OF CANTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

I THERMOSTATIC TIME CUT-OUT.

Specification of Letters Patent.

Patented July 9, 191%.

Application filed June 16, 1916. Serial Ho. 104,101

To all whom it may concern.

Be it known that 1, JOHN C. FRANCIS, a citizen of the United States, and resident of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Thermostatic Time Cut-Guts, of which the following description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates to improvements in thermostatic time cut-outs provided with automatically actuated means which will interrupt the circuit when the same is operated by an undesirable continuance of a normal current or by a sustained abnormal current.

The object of the present invention is to provide a thermostatic cut-out of simple construction and certainty in operation and which may be easilyreset to normal position without the necessity of replacement of ably including a parts.

This is accomplished by providing a power actuated switch having means normally restraining its action with releasing means actuated by an independent and lesser source of power said releasing means in turn being controlled by a thermostatic device preferbeing controlled.

The various novel features of the invention will be hereinafter more fully described and pointed out in the annexed claims. In the drawings: I Figure l is a front View of a preferred embodying my invention,

Fig. 2 is a side elevation of the same,

Fig. 3 is a vertical sectional view on lines 3-3 Fig. 1 and.

. Fig. at is a diagrammatic view of a fire alarm system equ1pped with the thermostatic cut-out illustrated in the preceding figures.

The thermostatic time cut-out forming the subject of this invention is illustrated herein as applied to a tire alarm system but it will be understood that its use is not limited to lire alarm circuits but that it may be employed generally to protect electric circuits from a sustained abnormal or an abnormally sustained normal heavy current.

-In fire lalarm circuits for buildings, signals, usually in the form of single stroke bells, are distributed throughout the buildheating coil in the circuit.

ing and are connected-in series in a low re sistance circuit adapted to carry a heavy current. This signal circuit is normally maintained open but is adapted to be closed to cause the operation of the signals by a relay circuit containing the usual fire alarm boxes and which carries a relatively small current. In operation, the breaking of the fire alarm box circuit acts through the relay to close the signal circuit thus actuating the gongs and as each box when pulled is adapted to interrupt the circuit a predetermined number of times the gongs will be struck a corresponding number of times.

In the ordinary operation of such a system the heavy signal actuating current is intermittent. and maintained only a short time. If, however, the fire alarm box circuit should be accidentally opened or if the relay should work improperly, the current through the signaling circuit would continue and intime might heat the coils which actuate the gongs to a dangerous degree. The present invention is designed to prevent the possibility of such accident by cutting out or breakng the main circuit after the signaling current has continued a predetermined time.

In order to" insure the proper operation of fire alarm circuits it is desirable that a small current be maintained through the alarm boxes and also the signaling circuit so that a visual indicator, such as a milammeter, may at all times indicate whether the circuits are in proper working order. For further protection a trouble circuit is often utilized to signal the breakage or grounding of the system.

An illustrative system of this character is shown in Fig. 4 in which a current supplied by a dynamo 1 or some other suitab e generator is carried by a main line a hrough 'a cut-out preferably of the type forming the may be provided for this line adapted to actuate a trouble signal as-will hereinafter more fully appear. The signal branch 0 which is of low resistance and adapted to carry a heavy signal actuating current is normally open, being provided with terminals 5, (3, adapted to be electrically connected by the armature 7 of a relay 8 in a supplemental high resistance fire alarm box circuit (l which may conveniently be connected at one end to a terminal 10 in .the high resistance circuit I) and at its opposite end by a line at to the common return line a so that current is always maintained in the high resistance branch I) and the alarm box circuit. A mil-ammeter 9 or other measuring device placed in said circuits will serve toindicate when the system is in operable condition. The circuit 01 contains the usual fire alarm boxes 11. each adapted when pulled" to interrupt the current a predetermined number of times.

When, in the operation of the device, an 1 alarm is turned in at one of the boxes the breaking of thecurrcnt in the alarm box line at causes the relay 8 to become de'e'nergized, permitting the armature 7 to drop upon the terminals 5, 6, thus completing the signaling circuit c,'and striking the gongs S. As soon as the alarm box circuit is again completed the armature 7 is withdrawn from the terminals 5, 6 and the hammer of the gongs are restored for the next signal.

As each box is adapted when pulled to 7 break the circuit (1 a predetermined number box at which the alarm is turned in.

' able switch 13 to break the main circuit if the normal heavv signaling current is abnormally sustained or if a sustained normal current is impressed upon the line.

Vhile the presence of the mil-ammeter in one branch of the signaling circuit may be suflicient to indicate the condition of the system, a trouble circuit preferably is provided to sound an alarmif the closed circuit becomes broken or grounded.

As illustrated herein the high resistance circuit 6 is provided with a relay 15 having an armature 16 forming a member of a switch cooperating with a terminal 17 in an independent circuit e comprising a battery 18 and a continuously ringing bell 19. The circuit 6 is normally maintained open, as the presence of a current in the line b energizesthe relay 15 and withholds the arma t-ure 16 from contact with the terminal 17,

Releasing or tripping means are provided for disengaging the locking means, said re leasing means including a thermostatic device, preferably in the form of a heating coil having an inclosed thermostatically expansible melnbcrsubjcct to the action of the heavy signal operating current.

The releasing or tripping means is pro-' vided with an independent source of power of less strength than the power means which tends to separate the switch members but adapted when released to cause the tripping means to impinge sharply upon the locking means to disengage the latter thus insuring a prompt and sure separation of the switch members and the breaking of the circuit. This locking and releasing means may be of any suitable character within the scope of my invention. A practical embodiment of the time cut-out aforesaid is illustrated in Figs; 1, 2, and 3 of the accompanying drawings in which the heating oil 12 and switch controlled thereby are mounted upon and insulated from a suitable base plate 21.

The line a of the main circuit is connected to an insulated terminal 22 which is connected to one end of the heating coil 12, the

other end of said coil being connected to an insulated terminal 25 having a contact spring adapted to engage the movable switch member 13. lated and having a spring contact member adapted to engage the movable switch member 13, is connected to the lines leading through the signaling and alarm box circuits.

The movable switch member 13 is secured to one arm 28 of a bell crank lever which is pivotally mounted upon a stud 29 extending Another terminal, also insufrom the base 21, insulation plates 30, 31

serving. to insulate the switch member 13 from the lever 28. The opposite arm 32 of the bell crank lever is preferably substantially L-shaped and is provided with a stud 33 adapted to be engaged by a shoulder 34 upon 'one arm 35 of an L-shaped detent which is pivotally mounted upon a stud 36 extending from the base 21. The detent is maintained in contact with'the stud 33 by a spring 33* anchored to the stud 36 and connected to one of the arms of said detent.

' The" bell crank lever is actuated bysuitable power niechanism, preferably a helical spring 37 surrounding the stud 29,one end of said spring being anchored to the base 21 and the other connected to the arm 28 of said lever so thatthe spring normally tends to throw the contact member 13 out of enagement with the stationary contacts 26, 27. lVhen however the stud 33 is engaged by the shoulder 31 of the detent the switch member 13 is locked in engagementwith the contact members 243, 27 and causes the completion of the circuit in the main line through the heating coil 12.

The spring 37 which operates the switch member 13 desirably is of considerable strength to insure the proper actuation of the switch and consequently forces the stud 33 firmly into engagement with the shoulder of the detent In order to cause the disengagement of the detent a special spring actuated tripping mechanism is providedwhich when released will strike the arm.

35 of the detent with sufficient force to insure disengagement from the stud 33, the tripping mechanism being in turn controlled by a thermostatic member actuated by the heating coil 12.

as illustrated herein the tripping mechanism comprises a lever 38 pivotally mounted upon a stud 39 projecting from the base 21, said lever 38 having its arm 4E0 offset and provided with a stud ll located at a dis tance from the arm 35 of the detent and adapted upon rotation of the lever upon its pivot to impinge upon said arm- The opposite arm 38* of the lever extends over and is adapted to be engaged by a thermostatically expansible member within the heating coil.

Independent power means preferably a spring 42 of considerable less power than the spring 37 is coiled about the stud 39 and having one endanchored to the stud 39 and theot-her end engaging the lever 38 tends normally to rotate the lever about its pivot 39 so that the stud 41 of the trippin mecha nism will strike the arm 35" with consider able momentum.

The lever 38 normally supported in the position shown in Fig. 1 against the tension of its spring by a thermostatically expansiblc member within the heating coil. The thermostatic member preferably is composed of two elements &3, a l having different co-eiiicients of expansion, such for exam-v ple as brass and steel, whichare secured together and at one end to a stud 45 projecting from the base and at the opposite free end are secured together by an l -shaped plate d6, which underlies the end of the arm 38 of the lever 38 when the thermostatic element is in normal or cool condition. The free end of the thermostatic member normally rests against a pin st? projecting from the base plate 21.

qlWhcn, in the operation of-the alarm circuit, an abnormal current is passed through the main line, or .when the normal heavy siga predetermined amount of time the heating coil 12 is raised in temperature, causing the expansion of the thermostatic elements 13,

44. These elements having different co-eflicients of expansion expand unequally thus naling current is continued through the line causing a deflection or bending of the ther- .35, thus releasing the detent from the stud 33 and permitting the bell crank lever 28 to be rotated upon its pivot under the action of the powerful spring 37 and removing the switch member 13 from its engagement with the stationary contact members 26, 27.

In order to reset the thermostatic time cut-out to normal position the arm 32 of the bell crank lever 28 is provided with a'handle 4:8 and also with'an extension 49 projecting over the path of the stud 4E1 on the tripping mechanism so that when the contact member 13 is moved into engagement with the sta tionary contacts 26 and 27 the tripping mechanism will be rotated against the action of its spring until therounded end of the arm 38 rides up beneath the plate 16 of the thermostatic element when the latter has cooled and returned to normal position, thus again locking the tripping mechanism. A. stop 50 secured to the base may be provided to engage the extension d9 of the arm 32 of the bell crank lever 28 and limit its movement.

While the tripping mechanism and the thermostatic member illustrated herein constitute a simple, convenient and preferred embodiment of my invention, it will be understood that various changes may be made within the scope of the following claims and that the embodiment of the invention herein shown and described is illustrative merely, not restrictive of the invention defined in the claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is;

1. A thermostatic cut-out for an electric circuit comprising switch members, power actuating means for giving relative movement to said members, a thermostatic means operable upon a sustained abnormal or an abnormally sustained heavy normal current in said circuit, means for locking said switch members in conducting position,- areleasing device normally out of contact with and un- "*3 influenced by said power actuating means and adapted to be released by a predetermined movement of said-thermostatic means and independentni'eans for actuating said ment to said members, a thermostatic means operable upon a sustained abnormal or an abnormally sustained heavy normal current in said circuit, means for locking said switch members in' conducting position, a releasing device engaging said thermostatic means and adapted to be released by a predetermined movement of said thermostatic means, and independent means for actuating the said releasing device to release the power aetuating means thereby to effect relative.

movement of the switch members.

A thermostatic cut-out 't'or an elgctric circuit comprising switch members, power actuating means for giving relative movement to'said members, means for holding said switch members in conducting position, a thermostatic means operable upon a sustained abnormal or an abnormally sustained heavy normal current in said circuit, an independent spring-actuated releasing device adapted to be held in operative position by said thermostatic means and normally uninfiuenced bysaid power actuating means adapted to be'released by a predetermined movement of said thermostatic means to effeet the release of the said power actuated means thereby to efi'ect relative opening movement of-said switch members.

4. A thermostatic time cut-out for an electric circuit comprising switch members, power actuated means for giving relative movement to said members, means for locking said power-actuatedmeans to retain the switch members in contacting position, a movable releasing device actuated by an independent mechanism of lesser power and operating when actuated to release the power actuated means, and thermostatic means controlling said releasing device and acting upon a predetermined degree of movement to free said releasing device to actuation by its power.

5. A thermostatic cut-out for an electric circuit comprising switch members, spring actuated means for giving relative movement to said members, means for locking said spring actuated means to-retain the switch members in conducting position, a

movablereleasing device actuated by an independent spring of lesser power and operating when actuated to release saidspring actuated means, and thermostatic means controlling said releasing device and acting upon a predetermined degreeof movement to free said releasing device to actuation by its sprin L A 6. A t ermostatic .time cut-out for an electric circuit'comprising relatively movable switch members, means normally tending to separate said members, detent mechanism adapted to retain sald members In contact,

'tripping means acting when released to strike a blow upon said detent mechanism and thereby to disengage the same, and thermostatic means in said circuit for releasing said tripping means.

7. A thermostatic time cut-out for an electric circuit comprising stationary and movable switch members, means normally tending to separate said members, detent mechanism adapted to retain said members in contact, independently actuated tripping means for releasing said detent mechanism, a heating coil in said circuit, and a thermostatic ed to retain said members in contact, tripping means for releasing said' detent mechanism and a heating coil in said circuit having an inclosed cxpansible member for controlling said tripping means, said member being constructed of connected elements having different co-efiicients of expansion whereby the deflection of said member upon expansion will cause the actuation of the tripping means.

9. A thermostatic time cut-out for electric circuits comprising a stationary member and a pivotally mounted cooperating switch member, a spring tending normally to separate said members, a detent ivotally mounted on a stationary'pivot a apted to engage said movable member, a spring actuatedtripping member in cooperative relation to said detent, a thermostatic member adapted normally to engage said tripping member and hold the same against the action of its springbut adapted under the influence of a.

predetermined amount of heat to release said tripping member and thereby cause disengagement of the detent and actuation of the movable member to break the circuit.

10. A thermostatic time cut-out for electric circuits comprising a stationary ember and a pivotally mounted cooperating -member, a spring tending normally to separate said members, a spring actuated detent pivotally mounted on a stationary pivot adapted to engage said movable member, a

spring actuated tripping member in cooperative relation to said detent, 'a thermo static member adapted normally to engage said tripping member and hold the same against the action of its spring away from said detent vbut adapted under the influence of a predetermined amount of heat to release said tripping member and thereby cause the same under the influence of its mounted cooperating movable switch memher, a spring tending normally to swing the movable member away from said stationary memberpa detent \pivotally mounted on a stationary pivot adapted to engage and retain closed said movablemember, a spring actuated pivotally mounted tripping member in cooperative relation to said detent, a heating coil having an expansible member engaging said tripping member against the action of said spring and adapted under the influence of a predetermined amount of heat to release said tripping member and thereby cause disengagement of the detent and the actuation of the movable member to break the circuit. v

12. A thermostatic time cutout comprising a stationary member and a movable switch member carried by one arm of a bell crank lever, a spring acting normally to force said movable member out of contact with said stationary member, a stud upon the other arm of said bell crank lever, a spring actuated detent mounted upon a stationary pivot and adapted to engage said I stud to lock said contact members in engagement, a spring actuated tripping member having a stud normally out of contact with and adapted to strike said detent, a thermostatic member normally holding said tripping mechanism against the action of its spring, and a heating means in said circuit adapted under the influence of a predeterminedamount of current to cause said thermostatic member to release the tripping member.

13. A thermostatic time cut-out comprising a stationary member and a movable switch member carried by one arm of a bell crank lever, a spring acting normally to force said movable member out of contact with said stationary member, a stud upon the other arm of said bell crank lever, a spring actuated detent mounted upon a stationary pivot and adapted to engage said stud to lock said contact members in engagement, a spring actuated tripping member having a stud normally out of contact with and adapted to strike said detent, a thermostatic member normally holding said tripping mechanism against the action of its spring, heating means in said circuit adapted under the influence of a predetermined amount of currentto cause said thermostatic member to release the tripping member and means carried by said movable member to cause resetting of said tripping member when said movable member is moved in reverse direction.

, In testimony whereof, I have signed my name to this specification.

- JOHN C. FRANCIS.

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