US3423953A - Refrigeration system including a thermostatically controlled valve - Google Patents

Description

Jan. 28, 1969 A. E. SPILLER 3,423,953

REFRIGERATION SYSTEM INCLUDING A THERMOSTATICALLY CONTROLLED VALVE Sheet Filed April l0, 1967 vF/G. l

A/DAN B Y fbakubgm S. W

Attorney Jan. 28, 1969 A. E SPILLER REFRIGERATION SYSTEM INCLUDING A THERMosTATIcALLY coNTRoLLED VALVE Filed April lo, 1967 Sheet 2 of 2 BY fwp 58%....

United States Patent 3,423,953 REFRIGERATION SYSTEM INCLUDING A THERMOSTATICALLY CONTROLLED VALVE Aidan Edward Spiller, 60 Wakefield Place, London, Ontario, Canada Filed Apr. 10, 1967, Ser. No. 629,745 U.S. Cl. 62-217 Int. Cl. F25b 41 /04, J 9/ 00 4 Claims ABSTRACT F THE DISCLOSURE Field of the invention The refrigeration system of this invention is particularly adapted for use by campers, picnickers, and for similar uses where it is desired to refrigerate a small enclosed volume with an inexpensive, light-weight refrigerating unit. For example, the refrigeration system of this invention might be used in a cooler chest of the type used by campers, and which has an enclosed volume of 2 or 3 cubic feet. In the past, it has been usual to cool such chest by placing a block of ice therein; or by the use of sealed, reusable containers (which might contain alcohol and water), and in which the contents may be prefrozen and liquify in use. When ice is used, the problem of collecting and disposing water formed as the ice melts is posed, along with the probability of damage to the cooler chest or its contents by the water. In the case of reusable sealed containers, they have a short use period, and access to a freezer or additional prefrozen containers is required if the cooler chest in which such containers are placed is to be used for more than a few hours.

Additionally, it can be seen that little or no control of the temperature 'within the enclosed volume intended to be refrigerated can be achieved using the cooling methods discussed above. For instance, as a block of ice melts, the temperature within the enclosed volume may rise sufiiciently as to promote spoilage of foodstuffs stored therein.

Description of the prior art It can be seen that a normal, closed refrigeration system would be impractical for such purposes as discussed above. Such systems require the use of motors, compressors, expansion chambers and heat exchangers. The Weight of such a system, not to mention its expense, all but precludes their use for such purposes as have been discussed above.

Summary of the invention It has been found expedient, therefore, to develop a refrigeration system which is light-weight and inexpensive, in which no liquid waste product develops, and which can be controlled so as to keep the temperature of the enclosed volume being refrigerated within defined limits. The open-ended refrigeration system of the present invention satisfies these requirements. Generally, this invention provides a refrigeration system in which pressurized gas is permitted to expand, from which gas expansion a cooling effect is achieved. The gas as it expands is permitted to escape usually to within the enclosed Ivolume being refrigerated, and is not recovered.

Thus, the refrigeration system of this invention is openended, and requires replenishment of the pressurized gas source as it is depleted. However, it is a feature of this invention that the pressurized gas source may be easily and economically replaced.

It is an object of this invention to provide an openended refrigeration system which is light-weight, economical, and provides cooling for an enclosed volume into which it is placed. i

A further object of this invention is to provide a lightweight, economical, portable refrigeration unit which employs pressurized gas as the refrigerant and permits the gas after it has expanded to escape, and which has thermostatic control of its operation.

Yet another object of this invention is to provide an open-ended refrigeration system which employs a refrigerating panel or surface as the heat exchange medium by which a cooling effect is achieved.

Brie;c description of the drawing Description of the preferred embodiments The refrigeration unit of FIGURE l is intended to be placed within a cooler chest or other -volume which is to be refrigerated. The unit, generally designated at 10, comprises a canister 11 for pressurized gas, gas conduit means or tubing 12, a thermostatically controlled valve generally designated at 13, and a carrying handle 14. The tubing 12, in the embodiment of FIGURE 1, is placed within a panel unit 15 which is described in greater detail below. An additional valve 19, whose purpose is discussed below, may be inserted in the position shown.

Unit 10 of FIGURE l is a light-weight, open-ended refrigeration unit. The canister 11 contains the pressurized gas which is used as the refrigerant, and is conveniently placed below panel 15. For ease of installation and removal of canister 11, it may be mounted as shown in blocks 16 and 17 which are adapted to secure the canister 11 in a rigid position. Blocks 16 and 17 may be secured along parting line 18 by any convienient means such as hook means which swings over a post (not shown), a sliding bolt, etc. The blocks may be hinged on the parting line opposed to parting line 18 shown in the drawing. The canister 11 may be secured to panel 15 in other manners than that illustrated in FIGURE 1.

The gas which is used as the refrigerant in the present invention may be any gas that can be pressurized and is commercially available in canisters such as canister 11. Such gases may include carbon dioxide, Freon, nitrogen, etc. The gas must be one that expands at atmospheric pressure when released from the canister, and which requires the absorption of heat as it expands thereby achieving a cooling effect. The pressurized gas Within canister 11 may, indeed, be liquied, depending on what gas is used. However, it is important only that the pressurized gas is permitted to escape therefrom in a controlled manner so that its expansion may be utilized in achieving a refrigerating effect. Valve 19, which may be opened and shut by such means as the knurled thumb screw 20, may

be installed as shown to open and shut the orifice through which pressurized gas from canister 11 escapes; and may be used so as to control the rate at which the gas escapes. Further, valve 19 may be closed when unit 10 is taken from service, so that no residual gas or pressure remains in tubing 12 as will become more apparent hereafter.

Canister 11 is generally of the type which may be punctured, and resealed by such means as valve 19. Tubing 12 may be lixedly or detachably attached to valve 19 at 21, but in use `a gas-tight communication is achieved between valve 19 and the tubing 12. In the embodiment illustrated in FIGURE 1, the tubing 12 is formed in a convoluted or serpentine fashion within panel 15. At least one surface 22 of panel 15 is of a heat conducting material such as copper or aluminum, and stippled aluminum of the -type used in freezer chests has been found to be very successful. The tubing 12 is in heat conducting relationship to surface 22, and may be bonded to the inner side of that surface. In the usual embodiment, both surfaces of panel comprise a heat conducting material which are in heat conducting relationship to tubing 12.

At the end of tubing 12 opposite to valve 19, there is a thermostatically controlled valve generally designated at 13, and which is shown in greater detail in FIGURE 2. This valve is illustrated generally at 23, and its operation is as follows: An elongated valve exit stem 24 is screwthreaded in fitting 25 at its bottom end. Gas in tubing 12 acts against the backside of valve 23, and the valve is opened permitting the gas to escape through exit stem 24. Thumb screw 26 is provided so that the valve may be manually closed by turning valve stem 24 in fitting 25. However, when the valve is in use in a open-ended refrigeration system it is desirable that the operation of the valve be automatic and be dependent upon the temperature of the ambient in which the refrigeration unit is working. The valve is therefore thermostatically controlled.

To effect such control, the valve stem 24 is slidably fitted within fitting 27, which is fixed to housing 29, near the upper end, of stem 24. Four bimetallic strips 28 are formed within housing 29 in a generally diamond-shaped configuration. The upper and lower apices of the diamond terminate at fittings 27 and 25, respectively. The outer apices and 31 of the diamond may be as illustrated in FIGURE 2 or as illustrated in FIGURES 3a or 3b, and as discussed in greater detail hereafter. Each bimetallic strip 28 is comprised in the usual manner of two metals having differing coefficients of thermal expansion. For the purposes intended by this invention, it has been found particularly useful to have the bimetallic strips with copper as the upper portion 28a and aluminum as the lower portion 28b, of each strip. As the ambient in which the thermostatic control is situated warms up, each aluminum strip 28b tends to expand at a greater rate than the copper strips 28a. Since each of the apices of the diamond are fixed, but since the outer apices 30 and 31 are permitted to move up and down against housing 29, the lower apex 25 of the diamond is lifted, and the valve opened. Conversely, as the ambient cools, apex 25 of the diamond is forced downwards, and the valve is closed. Thus, escape of gas through tubing 12 and exit stem 24 to the ambient is controlled thermostatically by the thermostatic valve unit 13. The housing 29 of unit 13 is one which permits an accurate sampling of the temperature of the ambient in which it is placed, and this may be achieved by making provision for air circulation through the housing.

The apices 30 and 31 may be formed as illustrated in FIGURE 2 or as illustrated in FIGURE 3a or 3b. In FIGURE 2, the outer ends of bimetallic elements 28 are mitred, and may be joined by any convenient means such as brazing or riveting. In FIGURE 3a, the outer ends of elements 28 are brazed to a cup 32 in which a ball or roller 33 iS Situated.. 1.11 FIGURE 3b, the outer ends of Velements 28 are brazed to a pad 34 which is permitted to slide against the adjacent portion of housing 29.

In operation, the unit 10 of FIGURE 1 is placed in the enclosed volume which is to be refrigerated. Valve 19 is opened, `and valve 23 is also opened so that gas is permitted to escape from canister 11. As the gas escapes, it begins to expand, and in expanding the gas absorbs heat from its surroundings. The expanding gas enters the gas conduit or tubing 12, and continues its expansion substantially through the length of tubing 12. Since the tubing is in heat conducting relationship to the surfaces of panel member 15, the outer surfaces of the panel become cold. The expanded gas escapes through the thermostatic valve control unit 13, and is released to the ambient through stem 24. If the gas is not fully expanded on its escape from stem 24, a further expansion will take place within the enclosed volume being refrigerated. However, when such a gas is carbon dioxide, such further expansion merely results in a further cooling reaction within the enclosed volume, and Dry Ice may be formed. In any event, a cooling or refrigerating effect within the enclosed volume is achieved by the cold surfaces of panel 15. Further, when such gases as carbon dioxide or nitrogen are used, the escaped, expanded gases have the additional advantage that they tend to restrain spoilage of foodstuffs. In addition, neither gas is noxious. Alternatively, the released gas from stem 24 may be ducted by the use of additional tubing to the exterior of the volume being refrigerated.

A further embodiment of the refrigeration system of this invention is illustrated in FIGURE 4. This embodiment also relies on the cooling effect achieved by permitting the expansion of pressurized gas, and is open-ended. However, a constrained but more free expansion of the gas is permitted in this embodiment, as will appear from lche following discussion.

A canister 11 of pressurized gas is punctured with a valve unit 35 through which gas may be permitted to escape. Over valve unit 35 there is a thermostatic valve control 36 which is essentially identical to tihat shown in FIGURE 2 as discussed above. Extending from the valve control unit 36 is gas permeable enclosure 37 from which the expanding gas is permitted to escape. In addition, the enclosure 37 is rotatalble so as to shut the valve off in the same manner as discussed with respect to valve 23 above.

The enclosure 37 may take the form of a perforated sphere as illustrated. Alternatively, it may have any form in which expanding gas is freely permitted to escape from its interior. Enclosure 37 is situated approximately centrally in globe 38 when the globe is in place. Tlhe bottom 39 of the globe 38 is adapted to fit about the top of canister 11, and fmay be secured thereto by such means as thumb screw 40. Several openings 41 are formed in the surface of globe 38, which openings may have screening placed thereover as illustrated. Handle 42 is secured to the top of globe 38 to permit portability, especially fwhen assembled to canister 11.

In operation, the refrigeration unit of FIGURE 4 is turned on by twisting the enclosure 37. Gas is thereby permitted to escape from canister 11, and passes through gas permeable enclosure 37 to tlhe interior of globe 38. The material of globe 38 is one having high heat conductivity, such as aluminum or copper. Since the gas is expanding within globe 38, heat is absorbed and a cooling effect achieved. Since most of the gas expansion occurs within the interior of globe 38, and the material of the globe is heat conducting, the outside surface thereof becomes cold. In addition, a circulation of air and expanded gas is permitted through the interior of lglobe 38 by means of openings 41. Thus, as stated before, the refrigeration effect within the enclosed volume is achieved, and when such gases as carbon dioxide or nitrogen are used, spoilage of foods within the enclosed volume is inhibited.

The above discussion has been related to two embodiments of an open-ended refrigeration system which is portable, light-weight and inexpensive. In addition, a thermostatically controlled valve for use 'with open-ended refrigeration systems has been discussed, which thermostatically controlled valve permits the maintenance of the enclosed volume to be refrigerated at an ambient temperature which may fbe predetermined. Each of the embodiments of the open-ended refrigeration system discussed above relies primarily for its refrigerating eiect on la surface or surfaces of heat conducting material which is in heat conducting relationship with a volume within which a refrigerant gas is expanding. In addition, a further cooling eifect may be derived from the expansion of the refrigerant gas within the enclosed volume.

Furtther purposes to which the refrigeration system of the present invention may be put include the refrigeration of medical supplies such as drugs, whole blood, human eyes, etc. during transport, say to a wholesale market. In some instances, it may be desiralble to use a single source of refrigerant gas for several units such as unit of FIGURE 1. In such cases, as many conduits may be provided as needed .which lead olf gas from a single pressurized canister to each of the individual refrigeration units in their respective enclosed volumes. Further alternatives and variations may be made to the refrigeration system of this invention without departing from the spriit and scope of the appended claims.

"Ilhe embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

I claim:

1. A refrigeration system comprising means for supplying pressurized gas; a laminated panel having at least one side thereof of a [heat conducting material; gas conduit means Within said laminated panel communicating at a iirst end with said source of pressurized gas, and

being in heat conducting relationship to said at least one side of said panel; said gas conduit means communicating at its second end with rval-ve means; said valve means communicating with the ambient, and being operable by thermostat means: said thermostat means comprising four bimetallic elements in generally diamond-shaped configuration, each of said bimetallic elements comprising strips of aluminum and copper securely bonded one to the other; said diamond-shaped configuration of said thermostat operable at one apex thereof against said valve means, and the apex opposed to said valve operating apex being spacially lixed with respect to said valve.

2. The refrigeration system of claim 1 wherein said panel means comprises two sides of heat conducting material, said gas conduit means being in heat conducting relationship to each of said sides.

3. The refrigeration system of claim 2 further comprising additional valve means at said iirst end of said gas conduit means.

4. The refrigeration system of claim 2 further comprising additional valve means at said rst end of gas conduit means; wherein said lgas conduit means is generally serpentine in configuration and is bonded to both sides of said heat conducting panel.

References Cited UNITED STATES PATENTS 2/1948 Kleist 62-515 6/.1963 Skinner 62-514 MEYER PERLIN, Primary Examiner.

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