US2374123A - Heat detector - Google Patents

Description

| F. OBERMEYER ET AL HEAT DETECTOR April 17, 1945.

Filed May 23, 1944 2 Sheets-Sheet 1 Z1. FT Obewzzzgyew Patented Apr. 17, 1945 HEAT DETECTOR Leo Francis Obermeyer and Edward C. Obermeyer, Grand Rapids, Mich.

Application May 23, 1944, Serial No. 536,936

'7 Claims.

This invention aims to provide a circuit maker and breaker adapted primarily but not exclusively to operate a signal, responsive to an abrupt rise of temperature, the device being unresponsive to a slow temperature rise, adjustment being possible, to the end that operation may take place at different speeds of temperature rise.

Within the scope of what is claimed, the structure described and shown may be changed, without departing from the spirit or the invention.

In the drawings:

Figure 1 shows in perspective, a device constructed in accordance with the invention;

Figure 2 is a side elevation, parts being broken away;

Figure 3 is a bottom plan;

Figure 4 is a rear elevation wherein the back of the casing has been removed;

Figures 5 and 6 are sections taken longitudinally of the device, one thermostatic element and associated parts being shown in one of the views specified, and the oppositely-disposed thermostatic element and associated parts being shown in the other of said views; and

Figure '7 is a circuit diagram.

In carrying out the invention, there is provided a support I, which, preferably, is an elongated, box-like casing, made of material which is a nonconductor of electricity, the material being weather-proof, to the end that it may not warp and alter the relative positions of the somewhat delicate parts which it houses. The support I is supplied with any desired number of air-admission openings 2, disposed as desired, the support having a hole 3, shown in Figs. 2 and 6, the purpose of which will be made manifest hereinafter.

Within the casing I is disposed a longitudinal arm 4 and a longitudinal arm 5, arranged in approximately parallel relation. A binding post 6 secures one end of the arm 4 to one end wall of the casing I, a binding post I exercising a like Mice with respect to the arm 5. The arms 4 and 5 are made of material which is responsive to heat and a conductor of electricity, metal being preierred.

The arms 4 and 5 extend practically the entire length of the casing I, the arm 4 being equipped with a laterally and outwardly inclined foot 8, adapted to be engaged by an adjusting device, such as a transverse screw 9, threaded into the casing I, the screw having-a turning head Ill, carrying an index II adapted to cooperate with a dial l2 on the casing I.

The arm 5 is provided with an outwardly extended foot I4; which bears against'a cam I5 on a transverse shaft I6, journaled in a bearing block II in the casing I. The shaft I6 has a head I8, provided with a screw driver kerf I9 accessible through the hole 3 in the casing I.

The numeral 20 marks an inwardly bowed thermostatic element, having its ends secured at 2I to the arm 4. The numeral 22 designates an inwardly bowed thermostatic element having its ends secured at 23 to the arm 5. In length, the thermostatic elements 20 and 22 approximate, respectively, the lengths of the arms 4 and 5,

At their place of closest approach to each other, the thermostatic elements 20 and 22 are supplied, respectively, with a contact 24 and with a contact 25. The thermostatic elements 24 and 25 are adapted to be brought into engagement, but they are a little off-center, so far as a horizontal axis is concerned. This causes the thermostatic elements 24 and 25 to have a wiping engagement, and they remain always clean and bright.

The thermostatic elements 20 and 22 are conductors of both heat and electricity. The arms 4 and 5 respond somewhat slowly to heat, s far as the expansion of those parts are concerned. The thermostatic elements 20 and 22 respond more rapidly to heat. The operation under consideration may be brought about by giving the thermostatic elements 20 and 22 a cross section which is markedly less than the cross section of the thermostatic elements 4 and 5. It will be noted that, since the arms 4 and 5 are secured only by the binding posts 6 and l, at one end, to the easing I, the arms may expand in the direction of their length. The thermostatic elements 20 and 22, however, are secured, respectively, at 2| and 23, t the arms 4 and 5, respectively, and, there fore, heat will cause the thermostatic elements to bow inwardly and bring the contact projections 24 and25 into engagement.

The numeral 26 designates a ribbon-like conductor of practically the same length as the casing I. The conductor 26 is of approximately the same cross section as the thermostatic elements 20 and 22, and, therefore, is a member which responds quickly to heat, so far as expansion and contraction are concerned, the part 26 being a conductor of electricity. The part 26 has a transverse end 2'1, bound'be'tween the upper end of the arm 4 and the upper end wall of the casing I and in electrical contact with the arm 4. The lower end of the conductor 26 is free, and the conductor tends to expand in the direction of its length. At its lower end, the conductor 26 has a lateral foot 28. r

The foot 28 of the conductor 28 i adapted to engage an adjustable contact, preferably in the form of a screw 29, threaded into the lower end wall of the casing I. The screw 29 has an external turning head 30, carrying an index 39 adapted to cooperate with a dial 3| on the lower end wall of the casing I. It may be remarked at this place that such terms as lower and upper are selected merely for convenience in description. The device may be mounted otherwise than in the upright position depicted; in Fig. l.

The screw 29 is threaded through an angular conducting strip 32, one portion of which extends position of the index 39 with respect to the scale or dial 3! having been noted.

The thermostatic elements 20 and 22 are carried, respectively, by the arms 4 and- 5 and are expansible transversely of the arms. The contacts 24 and 25 are convexed buttons, which are slightly oil center, transversely of the arms. The cam and the screw 9 are adjusting devices engaging the arms 5 and 4, respectively, the cam 15 being so mounted on the casing; I that the cam afiects gross adjustment of the arm 5", Whereas the screw 9 eiiects a fine adjustment of the arm 4.

along the lower end wall of the casing I, the mally-open thermostatic switch interposed in the otherportion of the strip extending upwardly; along the surface of the bearing block I]. Theshaft 13 is in engagement with the .upright .por.-';;

tion of the strip 32 and the strip, therefore, forms 29 and the cam [5 on the shaft l6. a i

The binding post 6 is joined by a conductor 33 to one side o fa source 34 of, electricali energy. The opposite side of the source 34 is joined bya conductor 35 to a signal 36, which may be either audibleor visible. A conductor 31 joins thesignal 36 electrically to the binding; post 1.

Lflv means of the shaft I6 and the cam [5, the arm 5 is operated togivean average positiomfor the; contact 25, and the position of the contact 24-, relatively to the contact 25,15 determined by operatingthearm 4, through the instrunientality of the screw 9.

When thetemperature rises slowly, the thermostaticelements and 2.2 tendto bow toward each other, but there i sufiicient time-for the arms 4 and 6 to become heated, and expand longitudinally, the contacts 24 and 25. being spaced apart ina. direction parallel to the-armsfi and 5. The signal circuitremains open, and; the signal 36 is notoperated. Such an operation takes placeduring ordinary temperature changes in the space wherein the device is located. I

In the event ofa rapid rise of temperature, such as may take place in the instance, of conflagration', the thermostatic elements 20 and 22 res'pond'to the temperature rise, and bring the 1 contacts 24 and 25. into engagement before'the armsd and 3 have had time to expand longitudinally and separate the contactsin a direction parallel to the arms. The signal circuitis closed, and thelsignal 36 operates. a

The arms 4 and 5 ultimately respond to the rapid riseof temperature, and. separate the eontacts 24 and 25, in a direction parallel to the arms l and 5: but thesignal36 continues to operate, because the thermostatic element 23, which acts quickly, like the thermostatic elements 20 and 22, has come into engagement with thescrew 29.

When the thermostatic element 26v touches the screw 29, there is established a signal circuit comto operate responsive to various speeds of tem perature rise. 7 I

The screw, 29 maybe advancedor retracted with respecttothefoot 2.8.of the conductor or thermostatic element 26, and the machine maybe set; as to operate at, a; selected temperature; the

'. The strip 26 and the screw 29 constitute a nor- P signal circuit, the sensitivity of the switch to heat bein'glapproximately the same as that of the members 20' and 22. The screw 29 and the strip 26 a link, electrically considered; between the-Screw. j

form relatively-movable switch-parts, the screw being under the control of an operator, thereby to vary the space between the: screw and the said strip and to predetermine thetime-interval between the spacing of the contactsand theclosing of theswitch.

' What is claimed'is: I

1. A circuit maker and breaker comprising, a support, thermostatic arms having their corresporiding ends secured to thesupport, the opposite endsoi thearms beingiree, toprovidefor-the longitudinal expansion of the arms, thermostatic elementscarriedby: the arms. and, expans'ible transversely of the arms, contacts carried. by. the

thermostatic elements, and means; for bringing the arms into an electrical circuit to be opened and olosed the thermostatioelements being more quickly responsive 'to heat than are the arms. whereby the contacts. will close together. before the arms havetime to expand. longitudinallylland space the contacts. I f

2. A circuitmaker'. and breaker constructed} as set forth in claim 1, and wherein the thermoe static elements are strips bowed toward each other, each. strip being, securedat. both ends.to one of the arms, the strips extendinglongitudinally of the arms. 1

3. A circuit maker andbreaker constructedas set forthin claim '1, and wherein. the thermostatic elements are strips. bowed toward each other, each strip. being, securedfat both ends. to one-of the-arms, thestripis extending, lo'rigitu: dinally of the arms, andjc ontactson, the. strips near the place wherethe strips, approachffeach other most closely, the, contacts being c'onve'xed and slightly on" center, transversely. of. thefstrlps', whereby. the contacts will have a wiping. contact with each other.

4.. A circuit maker andbreaker constructed as set forthin claim 1, in combination'with'an. ad'- justing means mounted on the support'and'ene gaged with one arm', to vary. the spacefbetwee'n the contacts. Y

5. A circuit maker and breaker constructedas set, forth in claim 1, in combination withla'djusting devicesengaging the respective arms, to vary the spacebetween the contacts, meansgiol other. of saiddevices on the supportiorifine ad justment;

. 6. 'A circuit maker andbreaker'constructedias set forth in claim 1, in combination withv a norlmally-open thermostatic swi'tc'hcarried by. the

support, and interposed in the circuitft'o. be

pandeclaIongitudinally.and opened it. I I:

7. A circuit maker and breaker constructed as set forth in claim 1,-in combination with a normany-open thermostatic switch carried by the support, and interposed in the circuit to be opened and closed, the sensitivity of the switch to heat being approximately the same as that of the thermostatic elements, the switch comprising relatively-movable parts, one of which is under the control of an operator, thereby to vary the space between said relatively-movable parts and to predetermine the time interval between the spacing of the contacts and the closing of the 6 switch.

LEO FRANCIS OBERMEYER. EDWARD C. OBERMEYER.

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