US2115502A - Thermostat - Google Patents

Description

April 26, 1938. s. VERNE-r THERMOSTAT Filed Jan. 30, 1935 INVENTOR ATTORNEY Patented Apr'. 26, 1938 UNITED STATES THERMOSTAT Sergius Vernet, New York, N. Y., assignor to Vernay Patents Company, Dover, Del., a corporation of Delaware Application January 30, 1935, Serial No. 3,999

11 Claims.

This invention relates to new and useful improvements in control devices and more particularly in thermostats and certain power transmitting means particularly adapted for use in connection therewith.

One object of this invention is to provide a new method of preventing or substantially minimizing supercooling in devices. employing substances having a crystalline stage in their thermic cycle of operation.

Another object of this invention is to provide eilicient means for rectifying and transmitting power from a pressure responsive means or diaphragm to a piston or other actuated member.

Further objects and advantages will appear more fully hereinafter.

Referring to the drawing wherein corresponding parts are represented by like numerals:-

Fig. 1 is a view in vertical central section of a thermostatically actuated valve embodying my invention,

Fig. 2 is a detail view in section showing a modied form of the cup or container of Fig. 1,

Fig. 3 is a view in longitudinal central section showing a variant structure also embodying my invention,

Fig. 4 is a detail sectional view of a porous filter plate,

Fig. 5 is a detail sectional view of a modified x form of pressure responsive means and comprises a corrugated metallic diaphragm suitable for use in the structures of the present disclosure.

Fig. 6 is a detail view in longitudinal section of a modified form of part of the structure of Fig. 1,

Fig. 'l is a detail view in longitudinal section of a modified form of piston, and v Fig. 8 is a detail view in longitudinal central section of a modified and compact form of cylinder structure.

The thermic motor shown in Fig. 1 comprises a hollow, preferably cylindrical cover or closure member I having an end Wall attached to the cup 2 and preferably rigidly secured thereto by means of the rivets 3. Clamped and sealed at its periphery between the end wall of cover I and the container or receptacle 2 and sealing the open top of the container there is a pressure responsive means such as a flexible diaphragm 4 made of rubberized fabric or any other suitably treated material or combination of materials. The cover I has in its end wall a central recess or chamber I having its open side facing the diaphragm 4 and is centrally apertured, as at Ib. Positioned in and extending through the aperture Ib there is a plunger or piston 5 connected to an alined shaft 6 by a sleeve nut 1 The shaft 6 is pivotally secured to a valve or vane 8, preferably a plate or disc of the buttery type, by a pivot pin 9. The vane 8 is located in a conduit or' sleeve I0 preferably concentric with shaft 6 and rigidly 5 secured to and in communication with the in-l terior of cover I. Within the recess la there is a spring II, held under compression between the cover I and piston head 5' of plunger 5, and which tends to keep the vane 8 in the fully closed posi- 10 tion. 'I'he valve or vane 8 is pivotally supported in the wall of sleeve or conduit I0 by bearing means I I, such as trunnions. A crystalline material I3 is located in the bottom portion of the cup 2, and is contained in the cellular structure 15 of the fins I2 which are preferably formed by a coiled metal ribbon. Overlying the crystalline material and lling the cavities between the separate crystals or groups of crystals' within the fins there is a force transmitting liquid I'I. This liquid also lls the space in the container 2 between the crystalline material I3 and the diaphragm 4 so that expansion of the material will be transmitted by the liquid to the diaphragm. Porous felt material I4 is located above the n 25 structure I2 and is pressed rmly down upon it by the perforated plate I5 which is fixed in position in the container 2 in any suitable manner.

The operation of the device starting from the closed position is as follows: A rise in temperature of the unit to the fusing point of the crystalline material I3 will cause the latter to change from the solid to a liquid state with an accompanying change in volume. Materials expanding while entering their liquid state such as paradichlorbenzene, paradibrombenzene, cyclohexane, are suitable for this purpose. The liquid I1 will rst be displaced from the minute spaces between the crystals. This change in volume will be transmitted by the liquid I1 to the diaphragm 40 4, which will then be pushed up toward the piston 5. As the crystals continue to fuse, the change in volume will become greater, and the liquid I1 Will continue to force the diaphragm 4 against the piston head 5', moving the piston 5 in a vertical 45 direction and changing the position of the vane 8. This action will continue until the crystalline material has entirely fused. 'I'he piston 5 will then have moved the vane 8 to open position. The boiling points of the crystalline and liquid material used are sufiiciently high to prevent vapor from being formed under all operating conditions.

A decrease in temperature sufllcient to .cause the crystallization of the material I3 will result in a corresponding change in volume. The tension of the spring II acting on the piston head i will move the vane 8 towards its closed. position. The full crystallization of the material I3 will allow the diaphragm 4 to recede slightly from the piston head 5 to its position,- Fig. 1, after the vane 8 has closed completely. This clearance is desirable to eliminate the effects of the slight expansion occurring in the various materials prior to a change in state.

Crystalline materials serviceable for thermostats are usually poor conductors, and if used in one unbroken mass, cause such lag in operation as to render the unit impractical for many purposes. The heat conducting fin structure I2 is in thermal contact with the walls of cup 2 and acts to rapidly and uniformly conduct external temperature changes to the modifying materials within the unit.

Damage to the diaphragm 4 may be caused by the crystalline material I3 coming in contact with it, either through chemical action or by the prevention of its proper flexing due to the crystals tending to form around its outer edge and upon its surface. The felt material I4 and the perforated disc I5 cooperate to localize the crystalline material I3, thereby preventing it from coming in contact with the diaphragm 4. Other and additional protective means such for instance as a cupped impervious auxiliary diaphragm might also be included between the main diaphragm 4 and the perforated plate I5. The closely spaced fins I2, by the creation of capillary forces and by their baffling effect, also cooperate to localize the crystalline'material I3. It is thus possible to shake or even tip the unit considerably without displacing the material I3 from its original position.

Solid solutions or other crystalline substances used as modifying materials vin thermostats of the type described are apt to separate or stratify when repeatedly submitted to temperatures high enough to cause only their partial fusion. These and other related phenomena modify the original volumetric characteristics of the crystalline materials, thereby affecting the calibration of the thermostat. The use of the shallow cup 2 and the location of the crystalline material I3 in the capillary chambers and spaces of the iin structure I2 reduce this tendency to a minimum, since the crystalline material I3 is uniformly heated throughout, and the liquid fraction resulting from partial fusion is retained in its original relation to the remaining crystals by the exertion of capillary forces.

Supercooling of the crystalline materials is here minimized by the use of the felt material I4. A few crystals become lodged in the felt material where they are not so readily subjected to changes in temperature. They therefore are not fused as quickly as the main mass of crystals located in the iin structure I2. When the temperature drops sufficiently. they act as nuclei from which crystallization is propagated throughout the entire mass. Among the cooperating materials found useful for minimizing supercooling may be mentioned activated charcoal, granulated quartz, and carborundum crystals. In general, initiating crystals having complex, complementary, or corresponding structures to the materials used, and characterized by a low thermal coefficient of expansion, are preferred. The choice of initiating crystals may be made on one further and important consideration: When modifying crystals of any one type are gradually fused, a transformation of pattern to one tending to persist even in quasi-dissolved state is evidenced. It is this latter pattern which is the more important in the selection of phasechange media, be they crystalline or otherwise. The difficulties of accurately determining this persistence pattern are conjoined by the more practical one of actually finding a structure of the type required. 'I'he ideal condition obviously rests in utilizing identical crystals both for motor action and as phase-change media.

Fig. 2 illustrates one structure by which this ideal condition has been successfully obtained. Here, the felt washer I4 and perforated metal disc 5 of Fig. 1 are replaced by a porous filter plate I5*, see Fig. 4. This filter plate acts to prevent the crystalline material I3 in either its liquid or solid form from entering the chamber I1* bounded by said plate and diaphragm so long as the non-modifying and force transmitting liquid (e. g., water) I1 is also present in the crystal containing chamber Ilb below plate I 5*, but readily permits the passage of such non-modifying liquid from the one chamber to the other. At the bottom of the crystal chamber, and projecting down from it, there is a tube 2\having a bore of cross-section and volume negligibly small compared to that of the crystal chamber and having its outer end closed and sealed, as lat 2*. After one heating, the material in this tube scgregates, and with a greater percentage of the high melting point material towards the bottom orouter end 2a, if materials which expand in fusing are used. Upon cooling, and before the normal crystallization range of the main bulk of material I3 in the fin structure I2 is reached, the material n in the hollow projection 2 crystallizes, thus providing seed crystals to propagate crystallization throughout said mass.

A further application of the principles above set forth is illustrated in Fig. 3. In this modification, a partition or plate 24 separates the heat chamber 24* on the left from the space or chamber 24h on the right containing relatively cool surrounding air. The bushing or supporting member 23 removably postioned in and closing an aperture 23* in the partition 24 serves to conveniently install and replace the thermostat unit mounted thereon. 'I'he elongated seed crystal tube or container 2h has its closed outer end 2 positioned in the cooler section or chamber 24D on the right and extends through a bore or aperture in the supporting bushing 23 in which it is secured by a packing bushing 22. A Since in general the crystals at the sealed end 2 will always remain in the solid state, when the crystals at the other extremity in the heat chamber 24* have fused, it is clear that there will always exist some intermediate point in the tube whereat crystals having structures corresponding to their persistence pattern may be found. Thus, phasechange media of the ideal type are here automatically provided, and Supercooling is minimized.

Like the structure of Fig. 2, that in Fig. 3 also utilizes the filter plate I5, This plate may be made from a variety of siliceous and other materials; and excellent results have been obtained with one made of porous bronze, illustrated in Fig. 4, The tube 2b opens at its inner end through the side wall of cup 2 in which it is hermetically sealed. As described above, the cup 2 contains a capillary heat transmitting nstructure I2 which receives the crystalline material I3, the plate I5* serving to hold the material I3 within the structure I2. The cup 2 is also closed and sealed by the flexible diaphragm 4 which is tightly clamped at its periphery between a shoulder on cup 2 and a flange on the closure member In this form of thermostat unit, the member YI 'is preferably an 'elongated hollow tube which extends through an Beyond the bushing or nut 2| the member Ic is preferably further restricted internally to provide a cylinder or piston bore to receive a reciprocatory piston 5b. The power factor in piston actuation is improved by utilizing a plastic material 5 between the diaphragm 4 and piston 5b. By forming a constricted cylinder as at 5 in the body section I so that the area of plastic material or other fluid exposed to the head of the piston 5b is a fraction ofthat exposed to the diaphragm 4, substantial piston displacement in the operating range is obtained.

In structures employing hydraulic power-` transfer, as described above in connection with Fig. 3, a corrugated metallic diaphragm 4, such as shown in Fig. 5, preferably with stiff center portion 4', not only increases the effective area and makes for compactness, but also through it a pistonaction is more closely simulated.

Due to the rather high pressures which may be generated in the hydraulic power-transfer type of thermostat, even when cylinder and piston have been accurately machined, gradual seepage of the plastic may occur. In Fig. 6, the body section and. cylinder head Ie corresponding to the closure member Ic of Fig. 3, has a plurality of ducts 30 exr tending longitudinally of the piston 5d and has a plurality of transverse intersecting ducts 3l with end closure plugs 32. The ducts 3| communicating with ducts 30 also intersect the piston cylinder 5e and at their intersection are provided with annular recesses 33. These ducts 3U and 3| and recesses 33 are filled with a substance of higher viscosity than the plastic material or fluid 5c, so that the rate of seepage will be decreased. The body section le is provided with a lateral peripheral flange l' by which it may be clamped and sealed to the cup 2 with the plastic material 5c abutting the diaphragm 4 or 4a.

Seepage may be substantially minimized by utilizing a piston structure permitting a hydraulic piston ring action, such as illustrated in Fig. '7. Here, the piston 5f is provided with an axial boring 30' which is intersected by one or more I or X transverse borings 3|'. of I or X bore ends is enscribed by annular recess 33'. Before use, i. e., before the piston is in-4 serted in its cylinder, the ducts are filled with a substance of higher viscosity than the plastic 5c and preferably insoluble therein.

For linear hydraulic power-transfer, the plastic must be substantially incompressible. When not so, the power factor decreases, the lag increases, and an unsymmetric cycle results. Such defects may be practically overcome by suitably decreasing the length of the chamber containing the plastic.

Due to the ease of transmitting power in any direction hydraulically, very compact body sections and cylinder heads may be designed. Fig. 8 illustrates one such design. In this Fig. 8, the closure member lt for the cup '2 has the piston Each set bore 34 transverse to diaphragm movement. In bore 34 is the piston 5x having a thrust member or shaft 6' secured thereto and extending through and guided in a sleeve nut 24'..v As in Fig. 1, the movement of the piston 5x is here opposed by spring Il positioned between piston 5x and nut 24', the piston being actuated by plastic material 5' moved by the diaphragm 4 or 4s4 (not shown) as in Figs. 3 and 6.

Various modifications and alternate combination of parts described will readily occur to those skilled in the art without departing from the spirit and scope of this invention as herewith illustrated and described. f

What I claim and desire to secure by Letters Patent is:-

1. In a thermostat, a container having a movable wall and a communicating elongated hollow extension, and a mass of fusible crystalline material in said container and said extension such that the ma'ss of material when in completely fused state will upon subjection to crystallization temperature crystallize initially in said extension thereby providing seed crystals for the remainder of said mass.

2. In a thermostat, a cup-like container having a movable wall closing and sealing its open side, an elongated hollow. tubular extension projecting from and having one end opening into said container, the other end of said extension being closed and sealed, and a mass of fusible crystalline material in said container and said extension such that the mass of material when in completely fused state will upon subjection to crystallization temperature crystallize initially in said extension thereby providing seed crystals for the remainder of said mass.

3. In a thermostat, a heat-transmitting container having a movable wall and a communicating elongated hollow extension, heat-transmitting means within said container and in heat conducting relation to a wall of said container, and a mass of fusible crystalline material in said container in intimate heat conducting relation to said means and in said extension such that the mass of material when in completely fused state will upon subjection to crystallization temperature crystallize initially in said extension thereby providing seed crystals for the remainder of said mass.

4. A control device comprising an apertured supporting member operable to close a partition aperture, a container carried by said member, a hollow body member extending through the supporting member aperture and having an opening communicating with said container, a movable wall interposed between and separating the interiors of said container and said body member, a piston in said body member and movable in response to movement of said wall, a fusible crystalline material in said container, said material being expansible on fusing and acting upon fusing to move said wall, a tubular member having an open end opening into said container and having its other end closed and sealed, said tubular member extending through said supporting member and containing said fusible crystalline material, such that upon fusing of the material in said container, the material in the closed end portion of said tubular member will remain in crystal state.

5. In an apparatus of the character described, a partition separating regions of different sensible heat, a hollow body member extending through said partition, a container in the region of higher heat and communicating with said body member, a piston reciprocal in said body member and operable to actuate means in the region of lesser heat, a plastic power-transmitting medium in said body member, a fusible crystalline material in said container and expanslble upon fusing, a movable wall operable -to transmit the expanslble force of said material to said plastic medium, and a tubu. lar member extending through said partition and having one end opening into said container and having its other end closed and sealed and positioned in said region of lesser heat, said tubular member containing said fusible material.

6. In a thermostat, a container, an expanslble fusible crystalline material in said container, a porous filter plate in said container and maintaining said material in situ, a liquid medium in said container, and a movable wall member in said container and overlying said liquid, said liquid acting upon fusing of said material to transmit the expansive force thereof through said filter `plate to said wall member.

7. In a thermostat, a container, an expanslble fusible crystalline material in said container, a porous bronze filter member in said container and maintaining said material in situ, a liquid medium in said container, and a movable wall member in said container and overlying said liquid, said liquid acting upon fusing of said material to transmit the expansive force thereof through said bronze filter member to said wall member.

8. In a thermostat, a container, an expanslble fusible crystalline material in said container, a

porous siliceous filter member in said container and maintaining said material in situ, a liquid medium in said container, and a movable wall member in said container and overlying said liquid, said liquid acting upon fusing of said material to transmit the expansive force thereof through said siliceous filter member to said wall member.

9. In a thermostat. a container having a hollow extension, fusible crystalline material in said container, and a phase-change medium in said extension and in contact with said crystalline material.

10. In a thermostat, a container having a hollow extension, fusible crystalline material in said container, means in said container and in intimate contact with said material to enhance the rapidity of transfer of temperature changes to which the container is subjected to and throughout said material, and a phase-change medium in said extension and in intimate contact with said material.

11. In an apparatus of the character described, a partition separating regions oi different sensible heat, a container in the region of higher heat and having a hollow extension projecting through said partition into the region of lesser heat, a fusible crystalline material in said container and expansible on temperature change, means closing an opening in the container wall and movable by expansion of said material, and a phase-change medium in said extension.

SERGIUS VERNET.

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