US1544549A - Thermostatic instrument - Google Patents

Description

July 7, 1925. 1,544,549

5. G. BARNETT THERMOSTATIC INSTRUMENT Filed April 14, 1922 Snowdon thermostat functioned. whole value in protection from fire is in the ability tem to operate its alarm while`the lire is in4 Patented July 7, 1925. .l

STOCKTON G.v BABNETT, 0F NEW YORK, N. Y.

mmos'rarxc :Nsrnuxnu'n' Application led April 14,1822.A Serial No. 552,687.

To all wlwm 'it may com-em:

Be it known that I, S'rooKToN G. BARNn'rr, 'a citizen of the United States, residin at No. 63 Morningside Avenue, New ork, county and State of New York, have vented certain new and useful Improvements in Thermostatic Instruments; and I do hereby declare the following to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which it' appertains to make and use the same.

This invention relates to thermostats, and more particularly to 'improvements in compensating thermostats useful in detecting rapid temperature variations.

Primarily, the object is to produce apparatus generally useful in fire alarm systems, and useful even in fire extinguishing or sprinkler systems; and more particularlyit is an object to produce a compensating temperature detector which uniformly functions to sound a fire alarm in all temperatures whether warm or cold, and which similarly appropriately functions to sound an alarm even though the daily or seasonable weather temperature conditions may rapidlychange.

It is common practice to use a bimetallic heat sensitive element, commonly known as a thermostatic bar, to perform a variety of purposes, as for example to detect a temperature change; and this was a comparativel simple undertaking where it was soug 1t only to detect or catch any predetermined lixed point of temperature because the thermostatic bar deflected as the temperature increased and broke or made contact on an electrical alarm or signal circuit. The development of this art was quickly impeded as it was conceived, due to the unfailing capacity of the thermostat to untimely produce false signals or alarms when subjected to seasonal increases in temperature, orother comparatively slow temperature increases due to industrial conditions or heating systems. By adjusting the thermostat to operate at a hi h tem erature, this diiiculty was overcome, ut 'suc adjustment introduced a fatal delay as to actual fires, because the fire gained headway before the Practically thedamage by of a lire device or sysf its incipient stage; and my mostat erforms this object.

On t e other hand, fixed temperature thermostats, askn'own in the art, when set to give a quick alarm offire so as to detect the fire in its inci ient stage, will necessarily give false a arms and particularly so when the thermostat and alarm system is used in the wintertime in unheated buildings, for in such a situation there necessarily arises seasonable and weather temperature changes to which the old fixed type thermostat cannot adapt itself, with the result that when such seasonable temperature changes occur the alarm prematurely sounds. The old devices thus have characteristics. which make them either too slow to be eiicient or too fast for service, and therefore, presently known'thermostats are so erratic that they are not useful in fire alarm systems.

Inventors anduengineers have long sought to so construct `and combine thermostatic parts as will-cause the device to quickly produce an alarm or signal upon sudden tempcrature variations, such as are caused byv fire; and which at the same time will dependably follow-up daily and seasonable temperature and Weather fluctuations yet steadfastly remain inert, with'out alarming; and to accomplish this purpose is to provide a successful fire thermostatic detector capable of valuable use in lire alarm systems, and until such is attained thermostats cannot be successfully used in fire control and alarm systems.

It was known that a compensating thermostat would be useful in this new field of endeavor; and by thermostatic compensation is meant the-ability of a thermostat to move up or down, follow-up so to speak, all slow temperature changes, known as weather or seasonal changes, without opening or closing a circuit, where at the same time it will produce an alarm if a quick temperature change occurs. Engineers and inventors improved therhave, it appears, correct theoretical knowledge of what apparatus is needed to carr out the purposes in View, but however suc physical apparatus has not been forthcoming, because noone as yet has produced a thermostat which""will adapt itself to weather and season temperature fluctuations without at the same time producing a false alarm,

and which will, conversely,.produce an alarm without compensating.A Apparatus has of course been produced and tried, but found ,missing inthe one particular if sucient in the other.` y A The object of my invention isv to pro- ,duce a compensating thermostatic circuit closer or a temperature detector which ernbodies such'improvements in' design, ar-

rangement, and construction of parts as will enable it to dependably compensate and follow-up all daily, weather, and seasonable temperature' changes, and at the same time of the irst'named thermostatic bar.

y circ'uit closer or temperature detectorwhich employs thermostatic bars of unequal sizes, but'- nevertheless will dependably compensate and actually perform that desirable purpose which others have sought to accom- The laccompanyin drawings illustrate one embodiment of'g m invention, and though there is describedya preferred form of construction and arrangement of. parts, l claim the right of protection as to such changes as obviously come within the scope of my invention.v

ln the drawings, plan view ofthe compensating thermostatic temperature detector; and Figure 2 shows a side view thereof.

Referrin nowinore particularly to the drawings or'a detailed description of the invention there is shown a post 4 made ofv insulating material supported on a base 5; and the base has terminal posts 6 by which this instrument is 'connected into an electrical fire alarm or sprinkler circuit.

A spirally formed thermostatc element 48 has its inner end anchored to the post and its outer .free end left unobstructed toV travel substantially concentric to the post;

and another thermostatic'element 9 has one end anchored to the post and its other end arranged movable near the free extrcnity D6 'of the bars, in this instance 8, has a down turned end so as to bring its contact part 10 in alignment with the contacthead 11 of the ot er bar, and. in this arrangement the contact points 10 and 11 are arranged in close relation. Each binding post 6 is.Y

connected through awire or barl l2l with the respective thermostatic parts so that the instrument can be connected into an elec- -tric circuit and' act as a switch to hold said circuit open during the time the con- 'capacity Figure l illustrates a tact points it) and v11` are held in spaced v. E deflect equally'inurate of travel d -An important featureA of this invention resides in the definite size and lredetermined relation existing between linear dimension and the thickness dimension of the two parts where the breadth of the parts preferably remain constant.

The two heat sensitive elements 8 and 9 are constructed of bimetallic stock equal in breadth or width. But, however, the element V8, being the longer one, is made of heavier .material', that is to say, it ismade of stock somewhat thicker' in-cross section than the part 9.l The fact that the longer part is made of heavier stock or vmaterial gives it the characteristic of slowly acquiring the temperature of the surrounding atmosphere, and consequently this bar acts -and deflects comparativelyslowly movement.

- '.lhey thermostaticrbar 9,-being shorter in length thanv the other bar, is made comparatively light in cross section, and is much thinner than the other bar; and thisy construction rovides the shorter bar with a or very rapidly attaining the temperature of the surrounding'medium of air which causes it to be quickly eected by quick 'temperature changes such as would be caused by lire thereby causing the bar 9 to rapidly deiect when subjected to the quick temperaturevariations.

It is desirable to make one bar of heavier stockV than the other in order that when the temperature quickly rises due to a fire, the quick acting element 9 may move its oth the head 11I awa from the point 10 on the bar i 8 and there y open the circuit, orit Yis readily seen that in case both bars were made of light material, they would both deflect with the same celerity, and the pur pose of this instrument would be` defeated. Then again, it is found, when a gradual temperature -variation `such as may occur from day to day in season, that a light and heavy thermostaticbar will gradually, at about the same rate of absorption,attain rounding atmosphere so that both bars will .or acquire the same temperature as the sur-v be stimulated 'and become equally active atsubstantially the same time when effected by this gradual temperature change. VThis -last described characteristic is necessary if the instrument 1sl to be successful, because possessed of this characteristic, the instrumentvwill compensate, follow-up, or adjust itself to the slow temperature variations, and at the same timewill not erratically open the circuit, or, in case of open circuit circl'iit.l i.

Now inasmuch as it is found necry to make one of'the'hars of thin light stock in instruments, vvwill, not 'erratically close the 1 order to detect fires as above described, and

.inasmuch asf it is essential that the two' liars l.. .-l 4f l and if the said long bar 8 is made consid-- erably thicker than the said thin bar 9, that the resulting performance of the instrument, as respectsslow gradual temperature changes, is of such character that both contact points 10 and 11 travel at substantially the same rate of speedfand through substantially-the same distance for unit slow grad-I ual temperature variations.

In the actual construction of this compensating thermostat and in order to enable one to practice the invention, I make, in

some types of the device, one part substantially six inches (6) long and fifty thousandths inches (.050) thick; and for 'the other part, I makeit one and eight tenths inches (1.8) long and fifteen thousandths inches (.015 thick, or some such ap ropriate length and thickness as will ear equivalent ratio to these figures.

It is also to be noted that the accompanyingl drawings show a closed circuit instrument, but an open circuit instrument can just as successfully be produced by following the plan of my invention.

Therefore an instrument built in accordance with the plans of this invention is capable of quickly detecting fire tem erature, and in addition thereto, is capab e of compensating or following-up the gradual daily. or seasonable temperature variations without causing the circuit to sound an alarm.

Having thus described the invention, what I claim is:

l. A compensating thermostat comprising two bimetallic4 heat sensitive, parts adapted to open or close acircuit by deflection, the parts having substantially an unequal len h ratio of six inches (6 to one and eig ttenth inches (1.8), an having an unequal thickness ratio of fifty thousandths inches (.050) to fifteen 'thousandths (.015) whereby both arts deflect substantially equally when in u enced by slow temperature variations and unequally when influenced by sudden temperature rises, and electrical contacts operated by the parts.

2. A compensatin thermostatic quick change temperature etector comprising biinches metallic heat sensitive elements having unequal length ratio and unequal thickness ratio, contact points carried thereon7 said ratios causing the rate of travel of the longer element tol substantially equal 'and compensate to that of the shorter element when subjected to gradual temperature changes thereby rendering inoperative the contacts, said ratios causing the rate of travel of the shorter one to be more rapid than' the longer one when subjected to a rapid temperature variation thereby rendering the contacts operable. l

3. A compensating thermostat quick change temperature detector having a long spiral bimetallic part, a contact head made on the end thereof, a short spiral bimetallic part, a contact head on the end thereof, said long and short s irals being disposed in parallel planes, sai long spiral made of thicker stock than short spiral whereby it compensates to and attains the same rate of travel as the short spiral when a slow gradual temperature variation occurs and does not when a quick temperature variation occurs.

4. A compensating thermostat quick change detector comprising heat sensitive bimetallic parts, contacts carried thereon, the comparative structure of the bimetallic parts being such that one part is made of .light Weight thin stock to impart thereto a high rate of tem rature absorption to cause this part to quickly deflect at high speed when subjected to quick temperature changes thus operating the contacts, and said light weight thin part being constructed relativelyv short in length to cause itl to substantially equal and compensate in speed to vthat of the other part whensubjected to slow temperature variations thereby not operating aforesaid contacts, the said other bimetallic part being constructed of thick heavy stock toimpart thereto a slow rate of temperature absorption whereby it lagsv or deflects slowly in speed when subjected to quick temperature changes thus contributing to the aforesaid operation of the contacts, said thick heavy part being made of substantial length to enable itto deflect equally in speed to that ofthe first named part when sub]ected to slow temperature changes thus aiding in maintaining vthe aforesaid inoperativeness of the contacts. 4 In testimon whereof I aix my si ature.- SIOCKTON G. BARNITT

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