US1769622A - Thermostat - Google Patents

Description

July 1, 1930. w. M. CHACE 1,769,622

THERMOS TAT Filed Jan. 2'7, 192B INVENTOR. y. 4 Ala/4w (Ls 4c: 7 5 4? BY ATTORNEY.

Patented July 1, 1 930 UNITED sT TEs PATENT oFFrcE WILLIAM M. CHAC'E, or nnrnorr, MICHIG N; ADELZBERT H. LINDLEY, Amrnuu ooornn, AND mum 2B. GHACE, EXEGUTORS or sen) WILLIAM M. crmcn, nn-

CEASED, ASSIGNORS TO W. M. CHACE VALVE COMPANY, OI DETROIT; MICHIGAN,

CORPORATION OF MICHIGAN I THERMOSTA'J.

Application filed January 27, 1928. Serial No. 250,016.

This invention relates to thermostats of that type-in which two metals of dissimilar thermal characteristics are welded together to provide a bar which, upon subjection to 5 varying degrees of'heat, tends to move by reason of the element having the greatest co eflicient of expansiontending to expand or contract more rapidly than that having the lower coeflicient of expansion.

Bimetallic elements of this type are mad-e in various forms as in spiral or helical coils or in normally straight bars. This character of element is used in various arts and heretofore Wherever the element is used in a position in which it is in contact with steam or moisture or with water, as in a flow control, the thermostat by reason of, at least one of its elements being made of a composition of nickel and iron tends to rust and becomes pitted and finally deteriorates to such extent as to become inoperative. I

Considerable effort has been made to increase the life of the element where subjected to moisture as for instance'by plating the same with nickel or other non-ferrous metal but such method hasbeen unsuccessful in that,

the plating deteriorates and peels thus exposing greater or less surface of the ferrous element or elements of which the thermostat is composed to contact with water or moisture. The object of this invention is to provide a thermostaticelement that is not materially aifected by moisture and this object may be accomplished by use of a non-ferrous material such as brass for the high expansion element welded to nickelsteelalloy as the nonexpansion. or low expansion element and welding a comparatively thin sheet of nonferrous material to the exposedsurface of the nickel steel alloy whereby both of the flat surfaces of the element are sufiiciently protected from contact 'withmoisture by nonferrousmaterial as to prevent rust as is hereinafter more particularly pointed out. An example of a structure embodying my invention is shown in the accompanying drawings in which- Fi 1 is a view showing'a portion of an au tomo ile engine and radiator therefor with 59 my improved thermostatic element in the .conduit therebetween and controlling a valve uses to which my improvedthermostat may be utilized and in which itis subjected to deterioration by moisture and in such rela: tionship the thermostat 1 when normally cool tends to hold the valve 2 closed to prevent fiow from the water space of the engine 3 toa radiator indicated at 4, the thermostat being located in the conduit 5 therebetween. This illustration is to be understood as being only a single instance of use of my non-corrosive thermostat.

In situations of this character where the thermostat is not subjected to high heat, the

expansion side of the element, indicated at (5,

may be ofbrass but other non-corrosive material having the necessary coefiicient of expansion may be used. This is welded to a strip of ferrous material 7 usually such as invar or other nickel steel alloy having a very low coeflicient of expansion. These two elements 6 and 7, that is, a corrosive and a noncorrosive element have been welded together heretofore but in such previous cases one face and two edges of the corrosive element 7 is in contact with water orwith moisture in many instances of use and therefore such previous device is'of short life.. I

' To overcome this defect I weld to the face of the corrosive element 7, opposite that to which the non-corrosive element 6 is welded, another non-corrosive element-8 which may be also of the same character as the element 6 and an element of high coefficient of expansion or other non-corrosive, element may be employed.

In the makin'gof such elements it is usual to startwith ablock 6 and a block 7, each approximately one-half inch thick and tothe exposed surface of .thenickel steel element 7 thereof coveredby non-ferrous or non-corrosive material and while the two edges may .15 be exposed tojmoisture, in the situations in which this element may be used, the deterioration at the edge is not of material mor-men't for the reason that rust may not eat i into 'the body of the ferrous material to such an extent as to produce inoperativeness in thenatu'ral life ofthe structure with which the thermostat is to be used; but should it 'be necessary to protect these edges they may have non-ferrous material welded to the 2 edges as well'as to the otherwise exposed surface of the ferrous material as is'suggested V in Fig. d in which case the ferrous material is entirely-enclosed within a non-ferrous shell welded thereto. I

9 It will be observedthat in my improved construction the ferrous nickel steel alloy has an expansion element welded to both sides thereof which. is a condition unknown in previous art in the manufacture ofthermostats of this character but the sheet 8 which is welded to the outerface of the ferrous material is of such thinness in the final element as to have little or no detrimental effect in the movement of the thermostat under variations in temperature but, nevertheless, is sufficient- '1 thick and so intimately associated with the errous material 'by the welding process as not to flake orpeel as with the plating methods heretofore used and thus provides a very 4 effective method of preventing deterioration through contact with moisture. My

improved thermostat is practically as efiicientf as the usual thermostatic blades hyreason of v the factthat the expansion element 6 is of so much greater thickness that it will cause a practically the usual movement of the blade ess the counteracting effect of the thin sheet a 8 welded to the opposite side of the element of lower coefiicient'of expansion and thus within commercial practicability the thermostat is sufiiciently effective for all the purposes for which such device may be used and provides a structure of long life and efiiciency-in such positions wherein it is'subjected v to or in contact with Water or moisture in v various forms as in flow control asis above suggested, or 111' the r'ehef valves of steam radiators andvanous other situations wherein it is subject to moisture.

5 In the construction as above described the meant any method whereby the various meta claim and desire to secure by Letters Patent non-corrosive element 8 is welded to the previously exposed surface of the corrosive nonexpansible element or element of. low coeflicient of expansion 7 and preferably is an expansion element or element of fairly high coefficient of expansion in order not to increase the relative influence of the non-expansion element butin the event it is desired to use a non-corrosive non-expansion element on the heretofore exposed side of the corrosive non-expansion element 7 of -the thermostatic couple, the thickness of the. corrosive non-expansible element may be decreased to maintain the influence of the nonexpansive side in normal relation with that of the expansion element.

It is also to be understood that, while in the fore oing description I have referred to the Wel ing of the elements together, these elements may in many cases be brazed together to form 'a unitary structure. There-' fore, it is to be understood that by weldlng as the'term occurs in the appended claims is elements of which my improved thermostat is composed have the surfaces thereof'secured together in a manner to provide a unitary structure having the described thermal and non-corrosive characteristics.

From theforegoingdescription it will be I evident that the structure is simple and efficient in operation preventing deterioration through contact with moisture and it 1s further understood that the invention is not confined to the form in which the thermostatlo couple is made. a

Having thus fully descrlbed my mventlon, its utility and mode of operatlon, what I of the United States ism5 1. A thermostat consisting of a bar of ferrous metal having a low coefficient of expansion .and'a bar of non-ferrous metal having a higher coeflicient of expansion, the elements being of substantially equal thickness and welded together, and a thinner bar of the said non-ferrous metal welded to the opposite face of the bar of ferrous metal.

2. A thermostatic element consisting of a bar of ferrous metal to one side of which is welded a bar of non-ferrous metal of different thermal characteristics and to the other side of Which is welded a relatively thin bar of the said non-ferrous metal. a

3. A" thermostatic blade consisting of a ferrous element having a low coefhcient of exansion encased in non-ferrous metal of 'a higher coefiicient of expansion, the non-ferrous metal on one of the flat sides of the blade being materially greater in thickness than that on the o posite side and joined together by a thin wa l of the same metal covering the edges of the ferrous element.

4. A thermostatic blade'consistin of a bar of nickel steel alloy having practically no lab variation in expansion under variations in temperature, and a bar of brass welded thereto "on one side of substantially'th'e same thickfness as' the ferrous metal, and a relatively thin bar of brass welded to the opposite sideof-the ferrous bar;

5. A thermostatic blade consisting of two metal elements of dissimilar thermal characteristics welded together oneof which'is noncorrosive and the other of which is corrosive through the action of moisture, and a rela-- 'tively thin bar of non-corrosive metal welded to the exposed side of the: corrosive element. 7

6.- A thermostatic blade consisting of two elements of dissimilar thermal characteristics having two similar surfaces secured together in such manner that the thermal characteristics of one are opposed by thatof the other and one of which is of non-corrosive metal or composition and the other of which is corroslve 1n the presence of moisture, and a a relatively thin element of the same non-corrosive metalsecured to the remaining sides of the corrosive element in a manner to shield the otherwise exposed surfaces thereof from moisture.

7. A thermostatic blade consisting of a corrosive non-expansion element and a non-corrosive expansion element welded thereto in a manner to encase the same thereby prevent ing oxidation of the corrosive element, the casing being of greater thickness on one side of the corrosive element than on the other to such degree as to counteract the expansion. efiect of the thinner portion of the expansion element. 4

In testimony whereof, I sign thisspecifica- I tion.

WILLIAM M. CHACE.

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