US3290889A - Thermal junction thermostatic chamber - Google Patents

Description

Dec. 13, 1966 KAZUKUNI NH 3,290,389

THERMAL JUNCTION THERMOSTATIC CHAMBER Filed March 11, 1965 :3 Sheets-Sheet 1 INVENTOR. w ZUMUN/ N/l mm CAEOTHE'QS Dec. 13, 1966 KAZUKUN! NH 3,290,889

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United States Patent O 3,290,839 THERMAL JUNCTEGN THERMOSTATIC CHAMBER Kazukuni Nil, Nishinomiya, Japan, assignor to Sumitorno Electric industries, Ltd, Osaka, Japan, a corporation of Japan Filed Mar. 11, 1965, Ser. No. 439,4l21 15 Claims. (Cl. 62-3) This invention relates generally to thermostatic chambers in which objects are placed for observation and treatment which includes programs for heating and cooling the objects under controlled conditions.

Accurate control of the thermal conditions of specimens undergoing study and treatment has long been recognized as a valuable asset to research and production. Many different types of structures have been constructed for this purpose.

Semiconductor material is known to have predetermined thermal characteristics when made up in thermal junctions and used to produce heat and cold with accurate control to effectively spell the success of the treatment or experiment.

Such controls may be employed as a supplementary source of temperature control to attain the degree of accuracy. On the other hand, the semiconductor may function as the only source of heat or cold with, of course, equal or greater accuracy. The semiconductor employed may be formed into a thermal junction or other thermal electric element by welding, soldering, brazing or otherwise applying a wall of high thermal conductivity to the crystal or crystals. These walls of high thermal conductivity when secured to the opposite faces of the crystals may then be finished to mate with the adjacent Wall surfaces of inner and outer housings. These housings are also made of high thermal conductivity material and can themselves function as the electric connectors for completing the circuit through the semiconductor junctions. However, the electric circuits may also be connected by bus bars or heavy conductor lines, or to the walls of the housing which may be poor electrical conductors but good thermal conductors.

One object of this invention is the provision of a thermostatically controlled chamber having inner and outer housings which are unitary in construction being made as a single casting of material of high thermal conductivity and impervious to liquids so that they may be fully or partially immersed to cool or heat the same. Such material may be copper, aluminum, iron, steel, stainless steel or clad stainless steel with an inner layer of copper or aluminum. Materials of this character are impervious to liquids and therefore may be bathed in gases or immersed in liquids to heat or cool the same.

Another object is the provision of an inner and outer chamber having a common opening or mouth. The mouth opening is preferably formed of insulating material as is the lid that closes the same. The space between the inner and outer chambers is filled with an insulation that prevents the conductivity of heat therebetween except through the interconnecting thermal junctions through semiconductors. These thermal junctions are not as large as the adjacent faces of the housings. Thus, the thermal conductivity is concentrated at the thermal junctions. The housings shown are substantially square but they may be polygons of a greater number of faces or they may be cylindrical with a junction on each face and on the bottom. Each thermal junction may be independently mounted relative to their housing face and independently connected to an electric circuit. Otherwise, they may be connected in groups. When not independ ently mounted they may all be connected in to an electric circuit.

Another object is the provision of a support for the bottom of the inner chamber within the outer chamber. Such a support may be produced by a plurality of upwardly open sockets in the inside of the bottom of the outer chamber adapted to receive and retain an insulator plug such as glass or a thermosetting resin. The upper face of such a plug or strip extending along between the inner and outer chambers which strip may be provided with a series of circular wells for receiving coil springs which when set in the bottom of each well and extend upwardly to engage and support the underside of the inner chamber. This spring may be made of glass or metal and it should have sufiicient pitch so that when under load the adjacent coils will not be engaged with each other. A spring of this character will transmit little or no heat between the inner and outer housings.

Another and more important object of this invention is in the mounting of the semiconductor thermal junctions with high thermal conductivity between their opposite sides and the inner and the outer housing respectively to a transfer of heat relative to the inner chamber, whether the heat is being supplied to the inner chamber or removed from the inner chamber. This thermal connection is preferably provided with a movable means of high thermal conductivity material so as to interpose at least two adjacent heat exchange surfaces to compensate for the relative expansion and contraction movement between the inner and outer chamber and their heat conducting exchange surfaces. Such a movable means is preferably set between aligned heat conducting surfaces and are attached to similar adjacent surfaces. If they are not so provided the pressure created by expansion and contraction may fracture the similar conductor thermal junctions.

The movable means that is effected by expansion and contraction of the connected parts may take the form of a wedge of which one or possibly two of its surfaces are inclined relative to the normally disposed surfaces of the adjacent aligned faces of the inner and outer housings whether they be polygonal or cylindrical. The wedge may have one normal surface and one inclined surface. The corresponding mating surfaces of high thermal conductivity will, of course, be complimentary to the wedge surfaces. A wedge of this character is provided with a spring means, one edge of which is connected to the wedge and the other end of the spring means being attached to some portion of the structure of the thermostatic chamber so as to continuously urge the Wedge conducting surfaces into thermal conducting contact with the mating adjacent heat exchange surfaces in the housing. The spring means may be coil springs lying one on each side of the wedge and connected to the housing structure so as to place the springs in tension whereby their pressure constantly urges the wedge into surface engagement with the adjacent thermal conducting surfaces. The spring means may, of course, engage the wedge and urge the wedge into thermal conducting contact with the mating adjacent heat exchange surfaces. In this way the thermal junctions will force the wedge to relieve the pressure due to expansion before the semiconductor thermal junction is subjected to a pressure sufficient to fracture the same.

Another move of providing a movable means between the aligned heat exchange surfaces is in the form of a spring means which can be a cantilever leaf spring but is preferably hoop shaped being either in the form of a continuous oval or preformed strap spring with their ends connected together. In each instance the spring itself forms one wall of the thermal junction which has considerable area matching that of the mating adjacent heat exchange surfaces either on the inner or outer chamber wall with the opposite side secured to the thermal junction. Springs, cantilever or hoop type, may be constructed of high thermal conductivity material such as aluminum, copper or brass, the same may be clad by mild or stainless steel. The heat exchange surfaces of these springs may be welded, soldered, brazed or otherwise permanently connected with the adjacent heat exchange surfaces. A particular advantage of this character of movable means in the thermal conducting path is that the total movement can be assumed in any direction by the mere flexing of the spring without it interferring in any way with the permanent thermal conductivity of the spring.

The thermostatic chamber made with an inner and outer housing that are substantially square in shape may provide a thermal junction of semiconductors connected to each of the four walls between the inner and outer housings and in such a structure, only two movable means need be disposed in the thermal conducting heat exchange paths disposed at right angles of each other; however, it is preferable to use four springs, one between each of the adjacent walls.

Another object is the provision of a heat exchange surface between the movable means connecting the thermal junctions and the adjacent thermal conducting surfaces wherein the thermal conducting heat exchange surfaces have high thermal conductivity but low electrical conductivity which permits electrical connections to be made directly to the movable means on opposite sides of the thermal junction whereas the thermal coonduction passes directly between the housing. This may be performed by using steels of low current carrying capacity made by a clad covering high thermal conducting qualities. If the movable means is represented by a spring on opposite sides of the thermal junctions, the selected stainless steel could be employed as a heat conductor but would function as a high resistance to current flow and the circuit leads could be connected directly to the springs or thermal junction members.

Another object of this invention is the provision of a vibrator which may be connected to either the inner or outer chamber or to both chambers which vibrator can be of any type but is preferably electromagnetic because it requires less maintenance. By providing a vibrator on either or both inner or outer chambers the whole system including the movable means supporting the thermal junctions will be constantly vibrated making their movable characteristics highly sensitive to slight changes in the expansion and contraction. This is true whether the movable support is of the wedge type or the cantilever spring or loop spring type. The vibrations would be preferable in all directions or in the direction of the movement of the wedge or normal to the flexibility of the springs which in this disclosure would be disposed at right angles relative to each other. The spring means would dispose the thermal junctions to be vibrated in a horizontal plane and the wedges would support the members and move in a horizontal or vertical direction. Thus, the wedges and the springs, the latter being of sufficient circular mills to carry the heat and the electric current, will be vibrated in its plane of greatest movement making them sensitive to slight forces of movement due to expansion and contraction of the assembly.

Another object of this invention is the provision of an insulated lid for the thermostatic chamber for the purpose of carrying electric connections to the interior chamber and in the inner housing, which electrical connections may, of course, be in a single phase or multiphase or coaxial cable for high frequency oscillating circuits for carrying on experiments and producing conditions under which the objects may be subjected to while in the thermostatic chamber. This lid may also be provided with a transparent window to observe the experiment within the chamber.

Other objects and advantages appear hereinafter in the following description and claims.

The accompanying drawings show for the purpose of exemplification without limiting the invention. or claims thereto, certain practical embodiments illustrating the principles of this invention wherein:

FIG. 1 is a horizontal cross section of the thermostatic chamber having unitary inner and outer housings connected through thermal junctions and a movable means.

FIG. 2 is a horizontal section of a thermostatic chamber having inner and outer housings connected through thermal junctions and a movable means wherein the chamber of the inner housing is additionally controlled by a circulating thermal system.

FIG. 3 is a view in side elevation of a thermostatic chamber with parts broken away and shown in section to illustrate the inner and outer housing connected through thermal junctions and a movable means.

FIG. 4 is a top plan view of the thermostatic chamber shown in FIG. 3.

FIGS. 5 and 6 are each views in vertical section of a thermostatic chamber with parts broken broken away to illustrate the inner and outer housing connected through thermal junctions supported by a modified form of movable spring means.

Referring to FIG. 1 of the drawings the inner housing 1 is suspended within the outer housing 2 and is connected thereto by means of a plurality of thermal junctions 3 there being at least two thermal junctions connected in line with each other between the opposite sides of the housings l and 2 which are polygon in shape and each surface of the polygon may be provided with at least two thermal junctions connected in line.

As shown in FIG. 1 the inner housing 1 with its inner chamber 4 is substantially square in cross section and thus requires two sets of opposed thermal junctions 3 to be aligned on its opposite faces and thereby connecting the inner housing 1 with the outer housing 2, the inner surface of which is also square but larger than the inner housing in order to receive the same.

Each of the housings 1 and 2 are unitary in that they are made of a single character of material that has a high thermal conductivity and is impervious to liquids. Such a material could be substantially any material that could be welded, casted, soldered, or otherwise pressed or formed, and its walls being impervious to the seepage of liquid thereinto. A molded single piece of material is preferable for each of these housings. An insulating means 5 surrounds the inner chamber and occupies substantially all of the inner space between the two housings except that required for the thermal junctions, and other [movable parts associated therewith.

As previously explained the thermal junctions 3 are preferably mounted in alignment with one on each side of the inner housing l and in direct contact with the plurality of heat exchange surfaces 6 on the outer walls of the inner housing. Heat exchange surfaces 7 and 8 on the inner wall of the outer housing 2. These aligned heat exchange surfaces may be welded, soldered, brazed,

. or otherwise secured to the metal plates on the op p-osite sides of the thermal junctions 3 which actually form the junction on opposite sides of the semiconductor indicated at 11 which mates and is secured to the thermal heat exchange surfaces 7 to fix the thermal junctions 3 in place. These semiconductors 11 may be single crystals or a multiple series of crystals stacked together and soldered, brazed, welded or otherwise secured to the metal plates 10 which may be uniformly finished on their outer faces engage or be secured for the purpose of exchanging heat with the heat exchange surfaces 6, 7 and 8.

In order that the relative expansion and contraction of each of these members which are directly connected in aligned series perform the heat exchange path between the two housings, it is necessary to provide some means that is capable of movement so that it will allow for the ex-pansi on and contraction and prevent the pressure from crushing or otherwise injuring the thermal junctions 3 or crushing or otherwise bending the walls of the chambers 1 and 2. This movable means in FIG. 1 and 2 is represented by the wedge members 13. The wedge member in FIG. 1 is slidable on the incline surface 7 which in this instance is an integral part of two sides of the inner wall surface of the outer housing 2. Each wedge 13- has one parallel surface 14 and one incline surface 15. As shown in FIG. 1 metal plate 161 on two of the thermal junctions 3, adjacent the wedges 13, functions as stationary heat exchange surfaces in engagement with the movable parallel surfaces 14 of the wedge. The wedge surfaces 15 are in engagement with the incline heat exchange surfaces 7 of the inner surface of the housing 2.

In order to urge the wedge into position to provide a continuous thermal conducting relation of the wedge surfaces and their adjacent heat exchange surfaces a pair of springs 16, one disposed on each side of the wedge and engaging the transverse rod 17 on the large end of each wedge. The other ends of the springs 16 are fastened to the cross plate 18 which is provided with a threaded opening to provide an adjustable screw member 20 that engages the abutment surface 21 at the point of greatest inclination of the inclined heat exchange surface 7 in which the end of the thumb screw Ztl has a rotary seat to hold this screw in place. Thus, by turning in the thumb screw 20 the springs 16 on either side of the wedge 13 draw the wedge tighter into thermal conducting relation with their adjacent heat exchange surfaces 6, 7 and 8.

When the expansion in one seat of aligned thermal junctions occurs, the forces pinch out the wedge 13, increasing the tension of the springs 16 but maintaining thermal conduction relation with the adjacent heat exchange inclined surfaces 7 and the outer heat exchange surface of the plates 111 which are indicated at 22.

It will be noted that there are four thermal junctions 3, with a pair in alignment in their respective major axes of the aligned walls of this interchamber 1 which is in the form of a square. There may only need be two thermal junctions employed in some installation. However, as shown in FIG. 1, there are as many thermal junctions as there are sides of the polygon which in this instance is in the form of a square. In FIG. 2 there are only two thermal junctions 3 aligned in one major axis of the housings but the incline heat exchange surface 7 of the housing 2 as shown in FIG. 1 is not present in FIG. 2 but is formed as indicated at 24- as an inner fiat heat exchange surface as a part of the wall 1 which is stationary relative to the wedge 13 which is mounted in the same manner to place the springs 16 in tension. The wedge 13 in this instance has its incline surface 15 in engagement with the incline surface 24 of the member 23. The parallel surface 14 of the wedge is movable against the fixed heat exchange surface of the plate 10 which is stationary relative to the outer case.

Thus, the wedge 13 is reversed in its application as shown in FIGS. 1 and 2. The structures of FIGS. 1

6 and 2 illustrate that the wedge may be adjacent the outer or the inner housing respectively; however, its function if precisely the same.

As shown in FIG. 2 the chamber 4 is provided with the circulating conduit connections 25 and 2.6 for the purposes of circulating a fluid within the chamber 4 of the inner housing 1. The lower thermal junctions 3 in FIG. 2 has an extended or enlarged wall member 27 that forms a junction with the semiconductor 11 and. extends to and is secured in thermal conductivity with the wall 6 of the inner housing 1.

If both of the housings 1 and 2 are made of a metal of high thermal conductivity they may be provided. with current conductors 30 and 31 for the purposes of placing each of the thermal junctions 3 in FIG. 1 into parallel circuit thereby control the current and the direction of the current flowing through the semiconductors of the thermal junctions 3 and thus determine whether or not heat is supplied to the inner chamber through what is knOWn as the Peltier effect. The conductors 30 and 31 may be connected to insulated binding posts or terminals such as 32 and. 33 as shown in FIG. 4.

Referring to FIGS. 3 and 4 the structure of the inner and outer housing 1 and 2 are more elaborate and the fins are extended only on 2 sides and are larged. However, the structure of the wedge blocks 13 is similar and are operated to be urged vertically upwardly by their respective springs 16 in place of horizontally as indicated. in FIGS. 1 and 2. In FIGS. 1 and 2 the stationary part that is provided with a complimentary incline surface 7 indicated at 23 in FIGS. 1 and 2 is provided with an underlip or shelf 28 to support the underside of the wedge as it is slid horizontally back and forth. The underlip 28 may take many forms such as a key and. slot on the wedge 13 and in the member 23 respectively.

As illustrated in FIGS. 1 and 2 a vibrator as indicated at 34 is connected to the outer housing to vibrate the same at a high vibratory frequency so that the wedges will be made sensitive to movement due to the expansion and retraction forces created by the materials of high thermal conductivity that connect the thermal junctions between the inner housing 1 and the outer housing 2.

As shown at the bottom of FIG. 3 the inner bottom wall of this outer housing is provided with an upwardly projecting stool or section 35 having a central bore to form a socket 36 for the reception of the plastic insulating holder 37 which mates with the socket 36 and is likewise provided with an upwardly open socket 38 to receive the lower end of the spring 40 the upward end of which extends out of socket 38 into engagement with the underside of the bottom of the housing 1 and is enable to resiliently support the same taking a mechanical load from the wedge surfaces in the heat exchange thermal conducting relationship. move vertically and have their incline surfaces 15 slidable against the corresponding incline heat exchange surfaces 7 which actually form the outer aligned heat exchange surface of the wall of the inner housing 1.

One or more of the springs 40 may be employed along the bottom of the housings. However, these springs being set in the sockets of independent insulating resins will conduct very little heat and electrically insulate the inner and outer housings 1 and 2.

The upper rim of the inner housing 1 in FIG. 3 is provided with an outwardly extending annular flange 41 in which the screw 20 is mounted to suspend the cross member 18 supporting the springs 16 to urge the wedge blocks 13 upwardly into contacting relationship.

The upper face of the flange 41 is engaged by the insulating annular mouth 42, which extends upwardly and outwardly of the insulating material 5 and defines the top 43 of the outer chamber 2. As illustrated in FIG. 4 the housings are rectangular and the annular mouth 42 In this structure the wedges is closed by the insulating lid 44 which carries the thermometer 45 and observation window 46 and a series of terminals 47 and which maybe raised or lowered by the handles 48. The handles 49 are placed on the outer housing 2 for carrying the thermostatic chamber. This lid may also carry a rotary shaft to rotate the specimen in the chamber 4 or to stir a mixture in the chamber 4. As illustrated in FIG. 3 some of the terminals 47 are connected to an inter-heat element St) within the chamher 4. Thus, when the lid 44 is placed in sealing position as illustrated in FIGS. 3 and 4, chamber 4 is completely sealed and. will remain in this way until open. Latch or locks may be provided to secure the lid so that it will not accidently become loosen by the operation of the vibrator 34.

In FIGS. 5 and 6 the wedges 13 have been eliminated and the thermal junctions 3 are supported between flexible leaf springs of high thermal and electrical conductivity. In FIG. 5, the leaf spring 51 is shown elliptical in shape and the opposite sides of its longitudinal axis 52 are welded, soldered or brazed or otherwise secured to the thermal junctions 3 on one side as indicated at 53 and to the wall of the inner chamber as indicated at 54 on its other side. Thus, any relative expansion or contraction movement in any direction is assumed between these strap loop springs which may also function as the heat and electrical conductor if desired. If not so desired, the wires such as illustrated. at 30 and 31 may be employed to directly connect the opposite sides of the thermal junctions 3.

In the structure of FIG. 6, the thermal junctions 3 are connected on opposite sides between strap type leaf springs 55 and 56 intermediate ends of which are secured directly to the inner and outer housing walls as indicated at 57 and 58 and the outer or free ends of the spring 55 and 56 are welded, brazed or soldered or otherwise secured to the thermal junctions 3. Here again the flexure of the springs 56 intermediate of their connection to form the aligned heat exchange surfaces to provide a continuous thermal conducting relationship with the inner and outer housings may flex to compensate for the expansion and contraction owing to the supply or withdrawal of the heat from the chamber 4 through the thermal junctions 3.

It is preferable to have the spring or straps 55 and 56 constructed of copper that is thicker adjacent the thermal junctions 3 than in their flexing positions so that the flexure of these springs will not be transmitted to the semiconductors 11 and cause them to fracture.

In spring supported thermal junctions of this character it is still best to provide a vibrator 34 so as to provide some vibration at all times to these spring members 51 and 55 and 56 to make them sensitive to very slight expansion and contraction forces.

I claim:

1. A thermostatic chamber for heating and cooling objects and including an outer housing with an annular Wall of high thermal conductivity, an inner housing with an annular wall of high thermal conductivity and mounted in said outer housing, an annular insulating mouth connecting both housings leading into a chamber in said inner housing to contain the objects to be treated, an insulating lid closing said annular mouth in both housings, insulation means between the walls of adjacent housings including said annular mouth, a plurality of thermal junctions including semiconductors having their oppositely facing ends directly connected to parallel walls of high thermal conductivity, a plurality of aligned heat exchange surfaces on said adjacent housing walls and on said parallel thermal junction walls in continuous thermal conducting relation to each other to complete a thermal exchange circuit between said chambers, and means to connect said thermal junctions in an electrical circuit to transfer heat relative to said inner chamber, and a movable means of high thermal conductivity material having oppositely disposed heat conducting surfaces and interposed between at least two of said mating adjacent heat exchange surfaces to compensate for the relative expansion and retraction movement between said continuous thermal conducting heat exchange surfaces of said inner and outer housings.

2. The thermostatic chamber of claim 1 including a vibratory means connected to vibrate said housings to induce movement of said movable means to make it more sensitive to changes in thermal expansion and contraction.

3. The thermostatic chamber of claim 1 wherein said movable means is a spring member.

4. The thermostatic chamber of claim 3 wherein said spring member is a closed elliptically shaped flat spring with long sides providing said heat conducting surfaces capable of greater flexibility along its minor axis and less flexibility along its major axis.

5. The thermostatic chamber of claim 1 wherein said movable means is a wedge, and spring means connected to said wedge to continuously urge said wedge conducting surfaces in thermal conducting contact with said mating adjacent heat exchange surfaces.

6. A thermostatic chamber for heating and cooling objects and including an outer housing with an annular wall of high thermal conductivity, and inner housing with an annular wall of high thermal conductivity and mounted in said outer housing, an annular insulating mouth connecting both housings leading into a chamber in said inner housing to contain the objects to be treated, an insulating lid closing said annular mouth in both housings, insulation means between the walls of adjacent housings including said annular mouth, a plurality of thermal junctions including semi-conductors having their oppositely facing ends directly connected to parallel walls of high thermal conductivity, a plurality of aligned heat exchange surfaces on said adjacent housing walls and on said parallel thermal junction walls in continuous thermal conducting relation to each other to complete a thermal exchange circuit between said chambers, and means to connect said thermal junctions in an electrical circuit to transfer heat relative to said inner chamber, and a wedge member of high thermal conductivity material having oppositely disposed heat conducting surfaces at least one of which is inclined, said wedge conducting surfaces complementary to and mating in sliding contact with at least two of said mating adjacent heat exchange surfaces, and spring means connected to said wedge to continuously urge said wedge conducting surfaces in thermal conducting contact with said mating adjacent heat exchange surfaces.

7. The thermostatic chamber of claim 6 wherein said inclined wedge conducting surface is adjacent and complementary to said heat exchange surface on said outer housing.

8. The thermostatic chamber of claim 6 wherein said inclined wedge conducting surface is adjacent and complementary to said heat exchange surface on said inner housing.

9. The thermostatic chamber of claim 6 wherein said inclined wedge conducting surface is adjacent and complementary to said heat exchange surface on one wall of said thermal junction.

10. The thermostatic chamber of claim 2 characterized by a circulating fluid cell in said inner housing to transfer heat relative to said inner chamber.

11. A thermal transfer junction having semiconductor thermal junction means with oppositely facing surfaces to be secured to spaced heat exchange surfaces characterized by a movable means of high thermal conductivity material having oppositely disposed heat conducting surfaces interposed between one of said heat exchange surfaces and said semiconductor thermal junction means to compensate for the relative expansion and contraction movement in exchanging heat.

12. The thermal transfer junction of claim 11 wherein said movable means is a spring means to compensate for r l ive exp nsion and contraction movement.

13. The thermal transfer junction of claim 11 wherein said movable means is a wedge with biased pressure means to maintain thermal contact there between to compensate for relative expansion and contraction movement.

14. The thermostatic chamber of claim 1 characterized in that said inner housing is unitary and impervious to liquids.

15. The thermostatic chamber of claim 1 characterized in that said outer housing is unitary and impervious to liquids.

References Cited by the Examiner UNITED STATES PATENTS Ryan 623 Bury 62--3 Kistler 623 Petrie 62-3 Eidus 623 10 WILLIAM J. WYE, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFI"(TN CORRECTION Patent No. 3, 290, 889 December 13, 1966 Kazukuni Nii It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 71 and column 8, line 37, for "chambers", each occurrence, read housings Signed and sealed this 19th day of September 1967.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer

Claims (1)

1. A THERMOSTATIC CHAMBER FOR HEATING AND COOLING OBJECTS AND INCLUDING AN OUTER HOUSING WITH AN ANNULAR WALL OF HIGH THERMAL CONDUCTIVITY, AN INNER HOUSING WITH AN ANNULAR WALL OF HIGH THERMAL CONDUCTIVITY AND MOUNTED IN SAID OUTER HOUSING, AN ANNULAR INSULATING MOUTH CONNECTING BOTH HOUSINGS LEADING INTO A CHAMBER IN SAID INNER HOUSING TO CONTAIN THE OBJECTS TO BE TREATED, AN INSULATING LID CLOSING SAID ANNULAR MOUTH IN BOTH HOUSINGS, INSULATION MEANS BETWEEN THE WALLS OF ADJACENT HOUSINGS INCLUDING SAID ANNULAR MOUTH, A PLURALITY OF TERMAL JUNCTIONS INCLUDING A SEMICONDUCTORS HAVING THEIR OPPOSITELY FACING ENDS DIRECTLY CONNECTED TO PARALLEL WALLS OF HIGH THERMAL CONDUCTIVITY, A PLURALITY OF ALIGNED HEAT EXCHANGE SURFACES ON SAID ADJACENT HOUSING WALLS AND ON SAID PARALLEL THERMAL JUNCTION WALLS IN CONTINUOUS THERMAL CONDUCTING RELATION TO EACH OTHER TO COMPLETE A THERMAL EXCHANGE CIRCUIT BETWEEN SAID CHAMBERS, AND MEANS TO CONNECT SAID THERMAL JUNCTIONS IN AN ELECTRICAL CIRCUIT TO TRANSFER HEAT RELATIVE TO SAID INNER CHAMBER, AND MOVABLE MEANS OF HIGH TERMAL CONDUCTIVITY MATERIAL HAVING OPPOSITELY DISPOSED HEAT CONDUCTING SURFACES AND INTERPPOSED BETWEEN AT LEAST TWO OF SAID MATING ADJACENT HEAT EXCHANGE SURFACES TO COMPENSATE FOR THE RELATIVE EXPANSION SURFACES TO MOVEMENT BETWEEN SAID CONTINUOUS THERMAL CONDUCTING HEAT EXCHANGE SURFACES OF SAID INNER AND OUTER HOUSING.

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