US1544342A - Thermostatic coil - Google Patents

Description

June 30, 1925.

l.. A. M. PHELAN THERMOSTATIC COIL Filed Sept. 22. 1924 lll/11111111111111111111- l Patented ,lu-ne 30, 1,925.`

g UNITED STATES 1,544,342 PATENT OFFICE.

' LOUIS A. M. rnnmm, or BELOIT, WISCONSIN, ASSIGNOR ro-ABSOLUTEcoN-'IAc-TOR CORPORATION, or BELOIT, WISCONSIN, A CORPORATION OF ILLINOIS.

THERMOSTATIC COIL.

Application leo. September 22, 1924. Serial No. 739,005.

To all whom t may (2o/noem.'

Be it known that I, LOUIS A. M. PIIELAN,

a citizen lof the United States, residing at Beloit, in the county of Rock and State of Wisconsin, have invented new and useful Improvements in Thermostatic Coils, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, `forming a part of this specification.

My invention relates to thermostatic coils and more particularly to la' device of this type wherein the bi-metallic strip is provided with an improved means for'efl'ecting an increased efficiency in the expansion and contraction thereof.` l

It is commonly known that a considerable part of the actuating force obtainable from bi-metallic strips is ordinarily wasted. Such strips comprise the controlling element in of the ribbon.

temperature control devices and are usually made of two metals fixed'together, having different coefficients of expansion, and sometimes being formed in the shape of aspiral. The purpose of such an arrangement is, of course, to use'the Spiral strip to turn or rotate a temperature `control device in response to temperature changes in the bi-metallic strip.

. I find, however, that where the spiral stripI 30 is in the form of a ribbon of considerable width, temperature changes will not onlyv tend to rotate one end of the ribbon with respect to the other, but will also tend to curl each and every' cross-sectional portion This cross-Sectional curling of the strip will strengthen the strip iagainst rotational effects. and thereby greatly diminish the effectiveness of the strip in controlling the temperature device.

A11 object of my invention is, therefore,

to provide an improved design of bi-metallic str-1p having means for minimizing the bending stresses in a crosswise direction, thereby increasing the rotational ability produced 4by expansion and contraction lengthwise, and permitting this lengthwise expansion and contraction to o erate unhampered Aby any tendency of the bi-metallic strip to strengthen itself against such action by curling.

' In the drawings wherein I have illustrated" Van embodiment of the my invention:

' Figure 1 1s a top plan view of abi-metallic strip embodying my invention:

preferred form of Fig.l 2 is a cross-sectional view of the same;

Fig. 3 illustrates in cross section the manner in which a bi-metallic strip will curl when not embodying my invention;

Fig. 4 illustrates in cross section the manner inv which a bi-metallic strip Vwill cur-l when embodying my invention and Fig. 5 is a Side elevational view of this strip formed in a spiral.

In the drawings the bi-metallic Strip 5 of the thermostatic coil is illustrated as comprising an inner metal 6 and an outer metal 7, the line of junction being-'shown at `8'. The two metals are Vsoldered or brazed together, so that the full effect of the Ldifferent expansions is obtained, there being no' possible slipping of one metal on the other. I employ two metals, Such as differ atleast in expansibility landmay be readily united by soldering or brazing. I prefer invar Steel, or the like, for the outer metal and bnass, or its alloys as the innermetal, but other combinations may be made with success; l

An important feature ofthe present invention is the form given to the outer metal 7 of the ribbon or strip forming the spiral.

tically unnoticeable and unable to strengthen the bi-metallic strip against rotational effects. e

Wheny formed spirally, the bi-metalllc Strip 5 is-usually quite wide. If so desired, more than one lon ltudinal oove 9Y mayibe provided, but this is entirely dependent upon the width of the strip. .Moreoven the coil is made more sensitive with thls groove which admirably Serves as means for increasing the eiic'iency during expanslon and centraction. vWhen imparting the actuating force, a liner degree of sensltlveness or prompt response is notlceable, beoaruse the lengthwise expansion and contraction (which are the rotational effects produced) lare unhampered and freeto act, without transverse bending stresses interfering.

It is believed that the principle underlying this invention, its functional law,A and the merits and advantages which it possesses will be entirely clear to those skilled in the art without further detailed description of other equivalent specific forms in which the invention may obviously be embodied.

Hence, without limiting the invention to.

the particular embodiment thereof herein selected forpurposesl of illustration and. description l I claim: 1. A bi-vmetallic element having at least i one of its metals devided into a pliiialit1 of strips. 4- E I 2. A thermostatic coil comprising metals of different coefficients of expansion and having at least one of said metals divided be` tween its edges to minimize the bending stresses in a crosswise direction. Y 3. Means for increasing the rotational 4:. Means for increasing the rotational..

effects of a spirally forme-d bi-metallic element comprising the provision of at least two strips serving as one of the metals, said strips being disposed along the edges of the other metal so as to localize the -crosssectioiral bending stresses adjacent theoutei' edge portions thereof.

5. A bi-metallic element` of substantial width havingits ou'ter metall separated so as to reduce cross-sectional curling of said element. l

6. A bi-metallicA element of. substantial width having at least one of its metals of such formation as to reduce cross-sectional(v curling of said element.` l

In witness whereof, I have hereunto1subscribed my name.y

Louis A. M. PHELAN.

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