US2838936A - Thermal responsive unit - Google Patents

Description

June 17, 1958 A. c; GOODRICH 2,838,936

' THERMAL RESPONSIVE UNIT Filed July 13, 1953 3 Sheets-Sheet 1 Win-' June 1953 c. GOODRICH 2,838,936

I THERMAL RESPONSIVE UNIT Filed July 13-, 1953 5 Sheets-Sheet 3 @and falls in temperature.

United States Patent TO 2,838,936 THERMAL RESPONSIVE UNIT Alonzo C. Goodrich, Winnetka, Ill. Application July 13, 1953, Serial No. 367,601 2 Claims. (Cl. 13-363 This invention relates to a thermal responsive unit and, more particularly, to a thermal responsive unit which combines a thermally expansible material with a material which changes its position in space either by a snap action and/or in response to thermal changes.

Many different types of thermal responsive elements have been devised in the past, including bimetallic elements, vapor pressure elements, as well as plastic and semi-plastic bodies which expand and contract on rises Bimetallic elements have usually had the disadvantage of not developing suflicient power to operate any substantial loads and this has also been true of vapor pressure devices and other devices employing bellows and the like.

Materials of plastic or semi-plastic nature have been developed in the past which expand and contract on rises and falls in temperature, but these devices have beenrelatively slow acting and gradual in their change from one predetermined position to another.

It is an object and feature of the present invention to provide a novel thermal responsive unit which has the advantages of a quick acting bimetallic snap acting member with the power advantages of a body, of thermally expansible material. r I

Another feature and object of the present invention is'to provide a novel thermostatic element in which a .body' of thermally expansibl e plastic material is confined in a housing by means of one or more bimetallic overcentermembers. p v ".A nother feature and object of the present invention is to decrease the reacting time of a normally slow acting thermally expansible material having great. amplification. further feature and object of the present invention is .to'provide a housing. for a thermally expansible.material having one ormorebimetal wall portions therein. Afurther feature and object of the present invention is to provide a flexible container for a thermally expansible material having a throttle effect on the expansion thereof. j. Still anotherand further object of the present invention is to provide a novel method and means for detecting thermal changes and for actuating rapidly a load element at some predetermined temperature. r

The novel features which I believe to be characteristic of .my invention are set forth with particularity in the appended claims. My invention itself; however, both as to its organization, manner of construction and method ofoperation, together with further objects and advantages thereof, may best be understood'by reference to .the following description taken-in connection with the of the present invention; I 1 I Figure 2 is a cross-sectional elevational view of the thermal responsive snap actin'g unit illustrated in Figure 1 ,838,936 Patented June 17', 1958 ice with the bimetallic snap acting disk in its normal low temperature position;

Figure 3 is a view similar to Figure 2 but showing the position of the bimetallic snap acting disk of the unit in its position after the device has passed through a critical predetermined temperature;

Figure 4 is a view similar to Figure l but illustrates a modified form of the present invention in which a solid cap member is employed rather than an open spider as is shown in the first embodiment of the present invention;

Figure 5 is a cross-sectional elevational view of modified form of the present invention;

Figure 6 is a view similar to Figure 5 with the exception that the over-center snap acting disk member is in its up position rather than in its lower position;

Figure 7 is a view similar to Figure 2 but showing the bimetal member supported in a V-groove rather than in a rubber gasket; and

Figure 8 is a view similar to Figure 2 but shows the flexible container panel member being formed only in part of bimetal.

Referring now to the embodiment of the invention illustrated in Figures 1 to 3 of the drawings, there is illustrated a thermal responsive snap acting unit including a housing member 11 having an offset shoulder 12 and an upstanding flange 13. Disposed within the body of the housing 11 is a thermally expansible material 14 which acts as a power generating element. This material 14 may, by way of example, include a crystalline material and an elastic binder material in solution; the crystalline material being expansible on fusion and being fusible in the operating range of the device. It may also include a finely divided solid material dispersed through and coated with the solution so that the multiplicity of particles is bound together by the elastic material into a solid body. A material of this type is described in United States Letters I Patent No. 2,259,846, although other materials having similar properties may, of course, be used.

This fusible crystalline material which, when combined with other materials, will undergo its change of state in the desired temperature range of operation of the device and which is also somewhat mutually soluble with another material serving as a binder may, by way of example, be diphenyl, dibromobenzene, dichlorobenzene, or other substances which experience a volumetric change over their fusion range. A satisfactory motive material for an element or body having the major of its expansion occurring between F. and F. is diphenyl, whereas for a range of F. to dibromobenzene may be used.

The binder material may, byway of example, be an unsaturated hydrocarbon polymer or vinyl chloride polymer.

Other examples of material which may be employed in the housing 11 are beeswax alone or in different compositions and paste mixtures of resin or wax with crystalline materials. Among many suitable formulae are the following:

Example I 60% C H Cl (paradichlorobenzene) 6.5% raw cocoanut oil 6.5% raw castor oil 27% commercial beeswax i Examplell 3 grams of beta napthol .3 grams of ester of gum resin It is, of course, important'to provide acover plate 3 .or diaphragm to maintain the thermally expansible mater a Within. the housing an to c a a Power transmitting element as the material 14 expands.

One of the distinctive features of the present invention is to provide-a bimetallic over-center disk 15 which has the dual function of retaining the material 14 in placeand also provides a quick acting force transmitting means and further provides a self-returning diaphragm to follow the contraction of the material 14 and return it to the position in Figure 2 of the drawings, as the ambient temperature drops below a predetermined critical operating point.

Since, in any bimetallic snap acting disk, the periphery must havecertain limited freedom of motion, it will be noted that the periphery 16 of the disk 15 is mounted in a rubber mounting ring 17 carried on the shoulder 12 of the housing 11. While rubber itself is not compressible, the rubber of the mounting ring 17 is free to shift sulficiently as to permit the limited motion necessary for the peripheral portion 16 of the disk 15. The ring 17 'is retained in place by means of a spider cover member 18 having a downturned internally threaded flange 18' which threads onto the upstanding threaded flange 13 of the housing member 11.

The spider 18 includes a hub portion or sleeve 19 through which a plunger or actuating member 20 freely slides. This plunger or actuating member 20 may have simply abutting contact with the bimetal member 15 or it may be secured thereto in any suitable fashion, such, for example, as brazing. When member 20 rides freely on member 15, it is preferably provided with a return means (not shown) to follow the disk back when it moves from its upper position as shown in Figure 3 to its lower position as shown in Figure 2.

With the open spider cover as shown, it will be observed that the entire unit may be immersed in a fluid 'whosetemperature state is to be responded to and the material 14 have its temperature raised or lowered by direct heat conduction through the wall of the housing member '11 as well as through the bimetallic over-center thermostatic disk 15. The disk 15 itself, of course, will also be sensitive to the temperature of such fluid.

' The critical temperature of the thermostatic disk 15 may be approximately the same, higher or lower than that of the expansible material 14. When its critical temperature is the same as that of material 14, the actual force which starts to shift the actuating member 20 will result from the expansion of the material 14. The final movement of the actuating member, however, will come suddenly as a result of the thermostatic element 15 passing through its over-center position. At this particular point, a substantial stress has already been set up in the disk 15 and it is able to carry a substantial load beyond its over-center position to its up position as shown in Figure 3 of the drawings.

As the temperature of the surrounding fluid drops below the critical operating point, the material 14 contracts and the thermostatic disk 15 will then suddenly snap through its over-center position again to its original position as shown in Figure 2. In doing so, it has returned the material 14 to its original position as shown in Figure 2 and during the entire operation, it has, of course, kept the material 14 confined within the housing 11.

When the critical temperature of the bimetal member 15 is higher than that of material 14, it will be noted that there is a differential or throttling effect on the initial action of the unit. The degree of throttling will, of course, depend on the difference in critical temperatures and on the stiffness of the bimetal material and the change in volume of the container 11. It will further be observed that as the bimetal member moves through its over-center position, there is a sudden enlargement of the chamber containing the expansible material 14, thus reli ng pa of h nter al stre s hi mate i This device is, of course, adaptable for use in fluids of a Wide y different charaqter. ei he liq i or gaseous It also is sensitive to temperature changes in solid members when the housing member 11 is seated thereon or in close proximity thereto so that heat may be transmitted to the material 14 either by conduction, convection or by radiation.

In a modified form of the present invention, a solid cover plate 2.1 is employed as is illustrated in Figure 4 of the drawings in place of the open spider 18 as shown in the first form of the invention. In all other respects, the device is similar.

A further form of the present invention is to substitute a non-bimetal snap acting member 22 as shown in Figures 5 and 6 in the place of bimetal member 15. In such event, a return means such as a spring 23 is necessary. This return spring causes the snap acting disk member 22 to snap back through its over-center position from the position as shown in Figure 6 to the original position as shown in Figure 5 as the ambient temperatuer falls through the critical temperature of the material 14. The compression spring 23 must, of course, react against some member and this is shown as a fixed support 24. The collar 25 is carried on the actuating member 23 for the spring to seat against.

Figure 7 shows a modified form of the present invention in which the bimetal member 15 is provided with a knife-like marginal edge 26 which is carried in an annular V-groove 27 of a housing 28 containing the thermally expansible material 14. In this form of the invention, the flexible gasket 17 is eliminated.

The bimetal member 15, as it moves through its overcenter position, may react against any suitable form 0 actuating or load member 20.

A further form of the invention is shown in Figure 8 of the drawings wherein a snap acting member 29 is formed partially of bimetal as at 30 and partially of a single metal as at 31. In the bimetal portion, the materials, of course, have different coefficients of expansion. The outer marginal single material portion 31 may be supported in the manner shown in either Figures 2 or 6 or it may be clamped rigidly by means of a clamping ring 32 threaded into the upstanding flange 33 of the container 34. The container 34 is filled with a thermally expansible material 14 as referred to in connection with the first embodiment of the invention.

From the above description, it will be apparent that I have provided a distinctive thermal responsive unit in which the lower load usually associated with bimetallic over center snap acting devices has been overcome by having the initial movement of the bimetallic element effected through the high force producing qualities of a thermally expansible material while the slow acting qualities of such a latter material have been overcome by employing the fast acting properties of a snap acting element after it has been preliminarily stressed. The combination of these two elements has resulted in an extraordinarily advantageous device not heretofore known in the art.

By the term bimetal, it is to be understood that this refers to two or more metals of dissimilar coeflicients of expans1on.

While I have shown certain particular embodiments in my invention, it will, of course, be understood that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover all such modificatoins as fall within the true spirit and scope of my invention.

I claim as my invention:

1. A thermally responsive unit comprising a housing having an inner cylindrical wall filled with a solid fusible thermally expansible material, said housing including a said housing, a retainer member mounted on said housing and extending over the opposite side of said ring from said shoulder and retaining said ring in sealing engagement with said shoulder, and a bimetal concave-convex diaphragm member mounted within said ring and forming one wall of said housing, the wall of said ring being sufiiciently free to accommodate free movement of said diaphragm from its concave to its convex positions.

2. A thermally responsive unit comprising a housing having a cylindrical inner wall filled with a solid fusible thermally expansible material, said housing including a shoulder extending radially outwardly from said wall, a yieldable gasket carried on said shoulder, a bimetal concave-convex diaphragm member engaging the wall of said gasket between the ends thereof and supported thereby for movement from its concave to its convex positions and forming one wall of said housing, a gasket retaining member mounted exteriorly of said bimetal member and engaging the opposite side of said gasket from said shoulder and retaining said gasket on said housing, said gasket retaining member including means for slidably supporting an actuating member in engagement with an intermediate portion of said bimetal member.

References Cited in the file of this patent UNITED STATES PATENTS 1,194,029 Kercher Aug. 8, 1916 1,639,888 Hawkins Aug. 23, 1927 1,884,794 McKee Oct. 25, 1932 2,146,731 Goodale Feb. 14, 1939 2,265,586 Vernet Dec. 9, 1941 2,471,240 Rider May 24, 1949 2,487,946 Senn Nov. 15, 1949

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