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` MÃ? Ey 346» c. F. ALBAN ETAL 2,403,895 THERMOSTATIC METAL Filed Feb. 2s, 1942 2 sheets-sheet 1 (n 0 fà NN à R J'O /50 35,0 450 „o 650 TEM/D. o CENT/@F1905 Í l C'Íarence Hüfoßneys. July 16, 1946. y ` c. F. ALBAN ErAL ` THERMOSTATIC 2,403,895 METAL ì Filed Feb. 2a; 1942 ` 2 sheets-sheet 2 î Manganese - Copper:- N/cke/ ¿6V/orf A - INV NTORâ ¿Va/»ence' . Hióan BY 5am @y 22 00d, Höfen/reqs Patented July 16, 1946 2,403,895 UNITED STATES PATENT «oF-FICE ‘THERMOstroîrîîîiivnrrsi.l l l l Clarence F. Alban, Pontiac, and Stanley R. Hood, Birmingham, `Mich., assignors to W. M. Chace Company, Michigan Detroit, Mich., `a 'corporation ` of Application February 28, 1942, Serial No. 432,832 2 Claims. (Cl. 297-15) l 2 This invention relates to thermostatic metal. 'I‘his application is a continuation-impart of our static metal, such as a Vhigh melting point, a high coefficient of expansion 4and high strength at high temperatures, but since manganese Ais brittle it alone cannot be used for `the high ex panding lamina of thermostatic metal. Because of `this manganese is alloyed with copper which produces a ductile alloy having a high melting application Serial No. 315,130, iiled January 22, 1940, now abandoned. Itis a common expedient in temperature re sponsive mechanisms and controls to utilize the diiference in expansion of two metals or alloys point, high strength at high temperatures and to effect mechanical movement. The mechanical a remarkably vhigher coeiiicient of expansion than movement is usually vobtained by usingïone metal having a vhigh> coeirìcient of expansion and an l0 either Vpure manganese or copper and a remark ably higher electrical resistivity. other metal having a low coeliicient of expansion According to Mechanical Engineers’ Handbook which are either Ífused together to form thermo by -Lionel S. Marks, fourth edition, 1941, page static bimetal or mechanically arranged as, for 624, manganese has a linear coeiiicient of ther example, a rod within a tube. The degree of movement obtained and the amount of work 16 mal expansion per degree F. at about ’70° F. of produced depends in general on three factors: 12.8 >< 10-5,‘nickel 7.2><1'0T6, and copper 9.12X'l0rï6. This remarkable increase .in -thermal expansion the strength of the materials used, the temper of the Aalloy in contrast to manganese is »remark alture chang , and the difference in expansion ably demonstrated, `by way of example, if one coefficients of the two metals. considers the coeflicient of expansion of an alloy The following metals and alloys having high consisting of 72% manganese, 18% copper, and coefficients ofi-expansion are commonly used in 10% nickel. According >to the law of mixtures, temperature responsive mechanisms and con one would expect a low linear coefficient of ex trols: copper, brass (60% copper, 40% zinc) and pansion for‘this alloy 0f 11.57 >< 10-6 per degree F. iron-nickel alloys to` which may be added chro at about '70° F. Actually one gets the remark mium, for example, .an alloy containing 22% ably high linear coefficient `of expansion of l5.5><l0”6. Because of this property of the manganese alloy, the thermostatic metal, which is the subject of this invention, Vhas a remarkably nickel, 3% chromium, 75% iron. Upto the pres ent no alloy >has ben developed which has both an expansionrate higher than a 60-40` brass and good strength‘characteristics at temperatures as high deflection rate. In fabricating the high expanding lamina the best analysis having the highest strength, high 50% 'nickel are commonly used. Invar (36% est expansion rate and highest .electrical `resist nickel, 64% iron) is one such alloy commonly ivity is a ternary alloy consisting of ‘72% Aman used for the low expansive element. The low expansive element `can also be made from an 35 ganese, 18% copper and 10% nickel. Although the above is the preferred analysis, other excel alloy of 17% chromium, `4% aluminum, balance high as 500° »C. For a` low expansive element iron-nickel alloys containing between 35% and lent alloys can be obtained for use as the high expanding lamina wherein the manganese ranges iron. It is an object of this invention toproduce a laminated thermostatic metal which has a higher electrical -resistivity and which will produce -a from `60% to 85% of theal‘loy by weight, `wherein the copper >ranges from 10% to `35% by weight of the alloy, and wherein the nickel ranges -from 5% to 30% by weight oi the -alloy. yAlthough the remarkably lhigher strain energy per degree tem perature difference than any other known ther mosta'tic metal. above are the preferred ranges Yof the constitu ents of the alloy, ‘these ranges can be widened . This invention also contemplates a laminated thermostatic »metal having an appreciably higher deilection rate than any other known thermo Vstatic metal. jThis object has been vachieved by utilizing a 4.5 somewhat to include other analyses which pro duce a material much 'better suited as vthe high expanding lamina , of thermostatic `metal than other known materials. In this enlarged range the constituents by weight would comprise nary alloy of manganese, copper and‘one o-f the 5,0 the 'following percentages of the alloy: mangan ese 15% t0 95%, copper 85% to 5%, nickel 0% to iron group metals, as the high expanding lamina of the thermostatic metal. >Manganese, both 30%. Cobalt or iron can be substituted Wholly or in part for .nickel 1in the ranges above speci commercially pure .manganese and electrolytic lied. However, nickel is preferred over either manganese, has properties which make it desir cobalt or iron. Nickel when alloyed with copper able as the high expanding lamina of thermo binary yalloy of manganese and copper or a ter 3 4 One of the best thermostatic bimetals available and manganese raises the elastic limit of the al loy and improves the physical properties in gen eral of the alloy. The nickel also gives the alloy stability, that is, causes the alloy upon cooling on the market is known as Chace #2400. The Chace #2400 bimetal has a low side of Invar (36% nickel, balance iron) and a high expand to travel along the same curve that it traverses 5 ing side of 22% nickel, 3% chromium, balance While being heated. In other Words, nickel iron by weight. It is interesting to compare the causes the alloy when its expansion and contrac'2400 thermostatic bimetal with the herein pre tion characteristics, due to thermal change, are ierred bimetal; namely, that having a low ex plotted on a graph, to travel along the same panding lamina of Invar and a high expanding curve upon a fall in temperature that it trav‘- 10 lamina of 72% manganese, 18% Copper, 10% eled upon a corresponding rise in temperature. Y nickel by weight. A very careful and exhaustive Manganese having a purity of 99.98% can be study of these two bizmetals has been made which produced electrolytically. So-called commershows that the thermostatic metal, which is the cially pure manganese usually contains about 3% subject of this invention, is surprisingly superior to 5% of impurities, such as iron, carbon, alu- 15 to the best of the known bimetals. minum and silicon. In the above analyses it is of this study is set forth below: preferred to use electrolytically pure manganese » throughout the entire range. However, commer- ' ' Advantage-gained through use cially -pure manganese -can be used up to a point of?? Mn, tig?, ciät a12% gril at which the commercially pure manganese ap- 2o ätafäggïïrgloääìrmggtauc proximates about 35% of the alloy. bimetal Where the manganese comprises more than 35% of the alloy, Y y 3. orX10-t «X10-o ~ „X10-a 50% constant temperature difference: Ident‘calslz‘e' Constant temperature diñerence: ' Ident‘calwe‘ght' Constant electrical current: Identi Temperature rlse cel size. 156% Constant eletrical current: Identi _ 170% 5. Strain energy Constant electrical current: Identi cal welght. 4. Strain energy Ni, balance Cu f anne” “Se f amounts of manganese over about 35% of the 1' Smm energy alloy should be electrolytically pure manganese. 25 ' , 58% The following expansion data is characteristic 2' Smm energy Of the ÍOHOWÍIlg allOYSZ ~ 30%. „X10-e M ' ` _ then to avoid brittleness it is essential that all Tânèp" 23% Mn,4% 27% Mn, 4% 32% Mn, 5% 9% Mn,5% A summary 30 cal slze. _ _ Fe, balance Cu Fe, bsleuee Cu Ni, 5% Fey balance Cu 3002221: 22Í4 2310 2413 2dr 35 ing thermal deilection of the rbimetal and is the 400 ----- -- 23'4 23-9 25-2 22-2 ----- -- Strain energy is the force developed by restrain Expansion data and representative resistance data is herewith set forth of the below specified alloys: ` Temperature range .Resistance Alloy ägzfägâsiggegflâë; em.per degree C. measure of the work which the bimetal cando. TheV above summary showsk (1) On the basis of a given temperature difference for pieces of the same size, the ratio of the strain energy avail 40 able through the use of the new manganese ther mostatic bimetal and the 2400 bimetal is 1.5 to 1; (2) This relationship, as mentioned immediately above in paragraph (l), for pieces of the same foot at 20° C. Weight of the new manganese thermostatic bi 45 meta1 and the 2400 bimetal is 1.58 to l. (3) QSXHH 900 The fact that the electrical resistivity of the new ma terial is considerably higher than that of the older 28X1Ü'“ sexie-ß ,IOXMH 11140 #2400 results in an added advantage in those 1,140 cases »where the temperature change is accom 950 50 plished from the passage of electric current. The ratio of the temperature diiïerentials of pieces of 38X10'” mms, at 20° Q_ 780 1,200 the same size of several materials when heated by the passage of the same quantity of electric `current will, in the general case where tempera 55 ture difference 1s a linear function of heat input, The above described binary and ternary alleysa due t0 their high coefficient 0f expansion and high electrical resistance are Very useful in the fabrication of thermostatic metals, particularly be proportional to the ratio of the electrical re SiStiVity for the materials in question. It ÍOllOWS then that-the ratio of the temperature rise of the new thermo-static bimetal '00 the #2400, when those thermostatic metals such as bimetal, tri- 60 pieces 0f the Same Size are heated by the passage mel-,el and other plural laminae thermostatie of equal amounts of electric current is 1.308 to l. metals. In the fabrication of such thermostatic (4) The raf/i0 0f Strain energy 01‘ WOrk resulting metals a lamina of the above manganese alloy is from the passage 0f equal amounts 0f electric fused or Otherwise bonded to a lamine, of a current through pieces of the same size of the new metal 0r- alloy having a, 10W coeñlcient of expam 65 manganese Inval' thermostatic bimetal and the Sion Such as Invar or nickel_ìr0n alloys contain_ #2400 bimetal is 2.566 to l. (5) The relationship ing between 35% and 50% nickel. If desired, the mentioned directly above in paragraph (4) for low expansion lamine, een be made from e, ter- pieces of the new manganese Invar thermostatic nary alley of iron, nickel and titanium In such bimetal and the #2400 bimetal of identical Weight case> thenickel content will range from 35% to 70 iS 2~70 t0 1- 50%, lelle titanium content from 1% to 4%J kand the remainder iron" The preferred jr0n_nicke1_ titanium alloy for the low side contains from 35% to 42% nickel, about 2.5% titanium, and the remainder iron. ‘ ' In the above described bimetal the difference between the COemCÍeIlÈS Of eXpal’lSÍOIl Of‘ the high and 10W 'eXpal'ldîng lamina@ iS greater than in _ those bimetals heretofore known. , The advan 75 tages of increasing the diiïerence in the expansion 2,4o3,895 5 rates of the two laminae are evident, 6 For ex ample, where such bimetal is used in temperature a water heater, the burner of which is controlled by a tube and rod type thermostat. The gas supply is admitted through pipe I into valve chamber 2 and passes through pipe 3 into the burner (not shown). The valve housing 2 responsive mechanisms and controls, for a given size of control element the deflection or strength of the element is increased compared with )a con trol element of other known bimetals of such given is provided with a valve 4 pivoted as at 5 and size, thus making the instrument or device in backed up by a compression spring E which tends which it is used more positive or sensitive. Fur at all times to hold valve 4 in the closed position ther, because of the high deñection rate and shown, thereby cutting off the ñow of gas through strength of such bimetal, where a given combina 10 pipe 3 to the burner. The hot Water tank is des ignated 1. tion of strength and deñection is needed in a control element, smaller amounts can be used Valve 4 is controlled by a thermostat in the than is possible where the control element is made form of a tube 8 secured to the tank 1 as at 9 and from other known bimetals, thus effecting a sav a rod I0 mounted within the tube 8 and contact ing in the cost of the control element. Since this 15 ing the tube 8 at Il. Tube 8 is made of the above high electrical resistance bimetal has a higher described high expansion alloy of manganese, deñection rate than any other known bimetal, it copper and nickel. The rod I0 can be any suit lends itself to great utility in the manufacture low expansion alloy such as Invar. In the posi of low amperage circuit breakers. tion shown, the water in the tank is at the ele 'I‘he thermostatic laminated metal which is the 20 vated temperature desired. As the temperature subject matter of this invention gives a greater of the water in the tank 1 falls, tube 8 will con work output for a given electrical input than those tract thereby raising rod l0 which swings valve 4 thermostatic laminated metals heretofore known. about its pivot 5 thereby opening valve 4 and This is important, particularly in electrical devices permitting gas to flow through line 3 to the heater. where the electrical resistance of the thermostatic As the temperature of the water rises, rod 8 will metal element is important. In such an electrical expand thereby lowering rod I0 which permits device Where a thermostatic element having a spring 6 to close valve 4 and thereby stop the given electrical resistance and deflection is de iiow of gas through line 3 to the heater. sired, it is necessary to use a relatively small piece We claim: of the heretofore known thermostatic metals. 30 1. Thermostatic metal comprising a plurality This was disadvantageous because such a small of joined metallic laminations, one of said lam piece of thermostatic metal gave correspondingly inations having _a relatively high coeiîcient of ex small power. On the other hand in such an elec pansion and comprising an alloy of the following trical device, due to the high electrical resistance constituents by weight: manganese from 20% up of the instant thermostatic metal, to satisfy such 35 to 50%, nickel 4% to 20%, balance substantially given electrical resistance and deflection a piece all copper; the other lamination having a rela of the instant thermostatic metal can be used tively low coefñcient of expansion. which is larger than the usable ‘piece of hereto 2. In a device responsive to temperature fore known thermostatic metals. Due to the fact changes to perform work or mechanical move that a relatively larger- piece of the instant ther 40 ment, a plurality of metallic members, one of said mostatic metal can be used, such piece of ther members having a relatively high linear coefficient mostatic metal will give more power. of thermal expansion and comprising analloy of In the drawings: the following constituents by weight: manganese Fig. 1 shows the temperature expansion coeiii from 20% to 50%, nickel 4% to 20%, balance sub cient data of two copper-manganese alloys com 45 stantially all copper; the other member having a pared with standard materials. relatively low linear coefficient of thermal ex Fig. 2 shows a bimetal strip having a high ex pansion and comprising essentially “Invar,” an panding lamina of manganese, copper and nickel alloy of iron and nickel. and a low expanding lamina of Invar. The two 50 laminae are welded together. CLARENCE F. ALBAN. Fig. 3 is an illustrative showing of a portion of STANLEY R. HOOD.