US2487968A - Thermally responsive unit - Google Patents

Description

Nov. 15, i949 Filed June 29. 1944 F. R. HIG LEY THERMALLY RESPONS IVE UNIT l '11.11111 243 f l 2 Smets-sheetA 1 4 l i I J, 5

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w uw a M BY mmm A 2) mnu lrae/#y signor; by mesne assignments, to Affiliated Gas Equipment, Inc., Cleveland, Ohio, a corporation of Delaware Application June 29, 1944, Serial No. 542,657

1 Y This invention relates to improvements in thermally responsive units of the laterally moving compensated or monometallic type. and to a a claims; (Cl. 297-11) u'nit by dishing the leg intermediate its ends, that is I form it with a -simple transverse curve which runs out to nothing adjacent the ends of the leg.

method of making such units. More particularly A the invention relates to that type of unit which is disclosed in my copending application, Serial' No. 528,548. led March 29, 1944, now Patent No. 2,455,306, dated November 30, 1948, upon" which the present invention is an improvement.

One of the objects of the invention is the provision of a unit having improved performance both as' to strength and as to stability under extended use, that is through a multiplicity of operations under stresses due to wide temperature changes. l

Another object is the provision in a monometallic thermally responsive unit of a leg member having flat ends in the same general plane and a reenforcing deformation intermediate those ends partly on one side and partly on the other side of that plane, thereby producing a generally straight leg with maximum strength against longitudinal buckling, but with a minimum disturbance of the stability under repeated stresses.

A further object of the invention is the provision of a method of producing the unit in accordance with which either of two different forms may be made from the same blank.

Other objects and features of novelty will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings.

Fig. l is a plan view on an enlarged scale of a unit embodying the invention.

Fig. 2 is an edge view of the same.

Figs. 3 to l0 inclusive are transverse sectional views taken substantially on the lines 3-3 to lll-l inclusive of Fig. l.

1l is a plan view of another unit formed from the same blank as that of Figs. l to inclusive, but bent in an opposite direction so that the conve; sides of the deformations, rather than the concave sides, face each other.

Fig. 12 is an edge view of the unit of Fig. 11.

Figs. 13 to 20 inclusive are transverse sectional views taken substantially on the lines I3-I3 to 29-20 inclusive of Fig. 1l, and

Fig. 21 is a fragmental perspective view showing a modied form of mounting.

In my copending application above mentioned, in which is disclosed a monometallic unit comprising two opposed legs integrally joined at metal and consequent their ends, I attain rigidity in each leg of the longitudinal line,

In the invention of that application the deformation is eiected by bending the sheet metal to one side only of theoriginal plane occupied by the blank. Consequently the leg is bowed in eect and has a bias toward buckling in one direction when placed under compression. Also, in the forming operation the .metal is considerably displaced.

In accordance with the present invention on the other hand, the same deformation is effected, but the metal isdisplaced from the general plane of the blank in both directions, one-half to one side and onefhalf to the other side of the originalV plane occupied by the blank. In other words, I so dispose the deformation in the intermediate portions of the leg that a neutral plane runs straight through the leg from one end to the other. Consequently, when the leg is placed under longitudinal compression it is not biased toward buckling in either direction. Furthermore, in thus deiorming the leg the metal is stressed only half as much as it would be if the deformation were all to one side, so that the deformation is maintained with greater stability under temperature changes than would otherwise be the case. The two members of the unit are formed from a blank of sheet metal folded along a median and the blank is similarly dished in the same direction on both sides of that line. When the bend is made in one direction, the concave sides of the dished portions face each other, and when the bend is in the opposite direction the convex sides face each other. This is an important feature of'the invention, because for some installations of the unit one form is'more desirable while for other installations the other form is better. Because of this method of manufacturing, two diierent forms are obtainable at a minimum cost for dies.

Referring now to Figs. 1 to 10 inclusive, the unit comprises two members 22 and 23 in opposed relation, that is facing each other. These members are flat and parallel at their respective ends, and at those ends are interconnected by aligned bends 24 and 25 along one edge of the unit of such radius as to space the members a distance substantially equal to the thickness of the metal from which the unit is made. At one end of the unit themembers 22 and 23 are provided with registering holes 26 for the reception of a screw or other mounting means, the metal about those holes being oiset one-half its thickness, so as to 3 assist in maintaining the said spacing of the members.

Between the bends 24 and 25 the edge of the unit is pierced, preferably by a slit, extending from one bend to the other. At the other edge of the unit the members are of course entirely unconnected. Hence that portion of the unit between the bends 24 and 25 constitutes a pair of legs 21 and 28 which are the active elements of the unit interposed between the mounting and the motion transmitting ends. The legs 21 and 23 are deformed to reenforce them against buckling longitudinally, these deformations being preferably opposite in direction, as illustrated. In the preferred aspect of the invention they conform with simple transverse curves extending entirely across the legs. The maximum degree of deformation occurs approximately midway of the legs at the section line 6 8. and the degree of deformation diminishes gradually in both directions from that line, as best shown in Fig. 2. In other words the radius of curvature is least at the section line 3 6 and increases gradually in both endwise directions until it becomes infinity at the ilat ends, as indicated particularly in Figs. 4 and 8, so that a maximum degree of rigidity is provided in the leg without impairing flexibility at those ends.

The deformations are so made that throughout the sections illustrated in Figs. 4 to 8 inclusive all of the neutral axes, indicated at n n. for each leg lie in a common plane. Preferably, as also illustrated, they lie wholly within the leg. Hence. in spite of the deformations. these legs may be said to be eilectively straight from end to end. and on that account they are free from any tendency to buckle longitudinally in either direction when the unit is under stress because of heat applied to one leg.

In making this unit, before the blank is bent along the edges 24 and 25, the slit is made in alignment with those proposed bends, the holes 26 are punched out and the metal around them on'set, and the two legs are similarly dished in the same direction. 'I'he fold is then made, completing the unit.

That form of the invention illustrated in Figs. 11 to 20 inclusive is approximately identical with the rst described form, except that the bend is made in the opposite direction, so that the convex sides of the dished portions oi' the legs, rather than the concave sides. face each other.

As in the rst described form, the active nortions of the unit in other words the thermally responsive portions, are a pair of opposed legs 30 and 3| having tlat ends in the same general plane. as indicated in Figs. 14 and 18, and having deformations intermediate those ends as indicated in Figs. 15 to 17 inclusive, the maximum degree of deformation occurring at the section line Ill- I6 about midway of the length of the legs. The bends made in the blank to bring the members of the unit into opposed relation are marked 32 and 33. The only diiTerence between the blank of this form and that of the first described form is that the o'setting of the metal around the registering holes 26' is in the opposite direction.

As in the ilrst described form of the invention, the neutral axes npn of all transverse sections of each leg are in a common plane, and the two neutral planes of the opposed legs are preferably parallel. The rigidity of the legs between their resilient dat ends is the same as in the ilrst describedform. f i' certain aspects of the to the ilat leg ends.

The neutral planes of the two legs of the unit are shown herein as generally parallel, but in invention they could be spaced further apart at the mounting end than at the freeend, the extent of such spacing depending upon the degree of deformation in the legs. When the legs are parallel and spaced apart a distance equal to the thickness of the metal, as herein shown, the two legs at the points of maximum deformation, corresponding to Figs. 6 and 16, substantially meet.

The form of the invention illustrated in Figs. l to 10 inclusive is particularly well adapted for use in installations where the unit must stand in an upright position and must be heated by llames from a plurality of jets one above another, for then the products of combustion from the lower names have a better opportunity to escape laterally and thereby permit air for combustion to reach the jets above. The form illustrated in Figs. 11 to 20 inclusive is used to great advantage where the longitudinal dimension of the leg must be disposed horizontally with the transverse dimension vertical. The ilame or flames for heatlng one leg may then be arranged to play upon the leg below the center line thereof and to wipe most of the width of the leg.

Either of the two forms ofthe invention described may be mounted, if desired, by the means illustrated in Fig. 21, where the two members of the unit at the mounting end have outwardly extending ears 40 and 4| opposite a bend 42 corresponding to the bends 24 and 32 previously described. The radius of this bend is such as to space the two members 43 and 44 of the unit correctly and the mounting screws or the like, not shown, extending through the openings 4l and 46 in the ears 40 and 4| assist in maintaining this spacing. The ears 40 and 4I are of course integral with the members 43 and 44 and are formed in the blank before it is bent to bring the members 43 and 44 into opposed relation.

It will be noted that in each principal form of the invention, the two complementary legs are disposed on opposite sides of an intermediate plane indicated by lines N-N in Figs. 5, 6, 7, 15, 16, and 17. Hence in operation, when the unit is responding to a differential in temperature between the two legs, the warmer of the two legs, throughout most of its length intermediate its ilat ends, is stressed substantially wholly in compressiomacting as a column or strut; whereas, the cooler leg is correspondingly stressed in tension.

When the direction of thermal diil'erential is reversed, the compression and tension stresses on the two legsare correspondingly reversed.

By this invention, whichever of the two legs is currently stressed in compression, by its described deformation of dished characteristic, it is reenforced against bending or buckling. Moreover, the amount of reenforcing is commensurate with the buckling tendency which it resists, being greatest intermediate the ends of the leg and graduated therefrom longitudinally of the leg,

Thus by the arrangement described, each leg has maximum reenforcement with minimum distortion of the deformed metal so that the leg will be least affected by high temperatures of long duration; and the outer surface of the leg which is to receive energizing heat-whether from a ame or from a radiant source-sumciently approximates ilatness to be highly efncient forthe purpose. -.g :L-.-

Having thus described my invention, I claim:

l. In a thermally responsive unit of elongated form adapted for lateral deflection, comprising a piece of sheet metal having a longitudinally extending bend providing a pair of elongated members disposed alongside each other in slightly spaced facing relation, said piece being perorate along a portion of said -bend intermediate the ends thereof to there provide a pair of laterally separate leg members, said members having integral interconnection longitudinally beyond said perforate portion adjacent one pair only of their edges: each of said leg members having at ends disposed in a common plane, and being of dished form between said iiat ends, to provide concavity across one face and corresponding'convexity across the other face of each, with transverse curvature maximum medial of its length and gradually decreasing therefrom to said flat ends, said unit having, adjacent one end, means for mounting it to provide for lateral deflection of its other end, responsive to temperature differential between said leg members. i

2. In a thermally responsive unit of elongated form adapted for lateral deflection, comprising a piece of sheet metal having a longitudinally extending bend providing a pair of elongated members disposed alongside each other in slightly spaced facing relation, said piece being perforate along` a portion of said bend intermediate the ends thereof to there provide a pair of laterally separateleg members, said members having integral interconnection longitudinally beyond said perforate portion adjacent one pair onlyvof their edges: each of said leg members having at ends disposed in a common plane, and being of dished form between said flat ends, to provide concavity across one face and corresponding convexity I being symmetrically dished oppositely to each across the other face of each, with` transverse curvature maximum medial of its length and gradually decreasing therefrom to said flat ends, the directionof said curvature of one leg member being opposite that of the other, said unit having, adjacent one end, means for mounting it to provide for lateral deflection of its other other to provide a single concavity on one side and convexity on the other side of each leg, the dishing deformations being so disposed with relation to the at ends of that leg that the neutral axes at all transverse sections of the leg lie in its said plane, and said legs being so spaced apart that they approach meeting at points of maximum deformation, said unit having, adjacent one end, means for mounting it to provide for lateral deection of its other end, responsive to temperature differential between said leg members.

FRANK R. HIGLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 361,899 Smith Apr. 26, 1887 447,422 Zenke Mar. 3, 1891 653,000 Dundon July 3, 1900 873,511 Cyphers Dec. 10, 1907 1,193,637 Inwagen Aug. 8, 1916 1,424,912 l Junkers Aug.'8, 1922 1,709,110 Bessonett Apr. 16, 1929 1,812,788 Hurxthal June 30, 1931 1,991,495 Derby .L- Feb. 19, 1935 2,086,857 Derby July 13, 1937 2,122,325 Rumball Jan. 28, 1938 2,185,436 r Gordon Jan. 2, 1940 2,204,791 Davis -.-1 June 18, 1940 2,267,164 Newton Dec. 23, 1941 2,392,065 Rodgers Jan. 1, 1946

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