US3112792A

US3112792A - Personal thermal device

Info

Publication number: US3112792A
Application number: US309416A
Authority: US
Inventors: Jr Robert E Coleman; Calvin D Maccracken
Original assignee: JET HEET Inc
Current assignee: JET HEET Inc
Priority date: 1952-09-13
Filing date: 1952-09-13
Publication date: 1963-12-03
Anticipated expiration: 1980-12-03

Description

Dec. 3, 1963 R. E. COLEMAN, JR. ET AL PERSONAL THERMAL DEVICE Filed Sept. 13, 1952 5 Sheets-Sheet 2 i I I l N I I I I mmvroa.

Roan E. (01.2mm an. (sum. 0. Mac Camus Anonntv Dec. 3, 1963 R. E. COLEMAN, JR., ETAL 3,112,792

PERSONAL THERMAL DEVI CE 5 Sheets-Sheet 2 Filed Sept. 13/1952 gVENTOR. ROBERT E. C LEMAN JR.

CALVIN D. MALCKACKEN IMTTOKNEY Dec. 3, 1963 R. E. COLEMAN, JR.. EIAL 3,112,792

PERSONAL 'I'l-IERHAL DEVICE Filed Sept. 13, 1952 5 Sheets-Sheet 3 1'0 bunmu' THEKMOPUMP INVENTOR. Roan E. (ousumu a.

\D v Q 8? (ALVIN D. Mattlmuuu F @W m. 80 901.

A'n'onuev Dec. 3, 1963 R. E. COLEMAN, JR., ETAL 3,112,792

PERSONAL THERMAL DEVICE Filed Sept. 15, 1952 5 Sheets-Sheet 5 THERMOPUMP --T THERMOPUMP INVENZOR. ROBERT E. (.oLemRN .m (awn: D. MNLCRAQQEN United States Patent 3,112,792 PERSQNAL THERMAL DEVHCE Robert E. Coleman, .lrx, Packanack Lake, and Calvin l). Macilraclren, Tenatiy, N.J., assignors to Jet-Heat, Inc, Englewood, NJ a corporation oi New York Fiied Sept. 13, 1952,8er. No. 369,416

' 16 Claims. (Cl. 165-46) This invention relates to improvements in personal thermal devices, and particularly to improved personal heatvariety of ambient temperature conditions, and that is' suitable both for heating and for cooling.

In accordance with preferred embodiments of the in vention, the foregoing and other related objects and advantages are attained in apparatus wherein a thin, flexible heat exchange structure, such as a garment, a blanket or a pillowcase insert, is provided with liquid conducting,

passages through which liquid is circulated by means of a heat operated pump (referred to hereinas a thermopump). As will be brought out more fully hereinafter, such an arrangement can be embodied in a very small apparatus package. which the apparatus is designed, the primary heat source for the thermopump may comprise an electrical heater, a small flame supported by a combustible fluid, or a variety of other similar heat sources.

Because of the simplicity and compact configuration of the thermopump, the apparatus has unusual versatility, and finds application in a variety of uses for which comparable prior art devices are of limited or no utility. Moreover, where heatingis required, the heat energyais used in a dual capacity as a source of motive power and for heating the circulated fluid.

A more complete understanding of the invention can be had by reference to the following description of illustrative embodiments thereof, when considered in connectioniwith the accompanying drawing wherein FIG. 1 illustrates a heated blanket arranged in accordance with the invention, with a portion, of the blanket surface broken away to show the interior construction,

FIG. 2 is a cross-sectionalview of the blanket of FIG. 1, taken on the line 2 2 of FIG. 1,

1 FIG. 3 is a perspective view of a header unit used in the blanket of FIG. l, a l i I FIG. 4 is a fragmentary view of a thermopump, showing electrical heating of the pump generator,

FIG. 5 illustrates 'a heated suit arranged inaccordance with the invention,

FIG. 6 illustrates a thermopump and fuel container assembly suitable for use in the system of the present invention, 1

FIGS. 7*9 illustrate modified forms of fluid heating circuits embodying the invention,

V attains? Patented Dec. 3, 1%63 is circulated in accordance with the present invention may take any one of a variety of diiferent forms. In general, what is contemplated is a flexible structure or web of material capable of conforming to or serving as a covering for part or all of the human body, and may comprise a garment, such as a jacket, coveralls or the like, bedclothing, such as a sheet, a blanket, a sleeping bag, a

pillow insert or a mattress cover, or similar items of personal use. a

By way of introduction, the invention will first be described as embodied in ,aheated blanket.

Depending on the specific use for Referring to FIGS. 1 and 2 of the drawing, a heated blanket 8 arranged in accordance with the invention comprises a thin,.flexible two-layer heat exchange structure 1d, 11, provided between the fabric layers 10, 11 with liquid conducting passages 12 extending throughout the blanket and through which heated liquid is circulated by a thermopump l4.

The superposed fabric layers l0, 11 are sewn together along the outside edges and along spaced lines 13 to provide channels for holding flexible tubing, such as rubber or plastic tubes, forming the liquid conducting passages 12.

For clarity, only a small number of relatively large cross-section tubes 12 are shown in FIGS. 1 and 2. In

r actual practice, tubing of capillary dimensions is preferably used, not only to decrease the quantity of circulating liquid in the blanket structure andto make the surface irregularities due to the tubing less noticeable, but also to avoid stoppages due to kinking of the tubing 12. For example, tubing with an inside diameter and a wall thickness of, say, 40 mils, is found to be appropriate. A suitable material for the tubing is a plastic material, such liquid will enter the blanket through the input header 16,

flow through the various loops of tubing 12 in parallel, and flow out through the header 1%. This. parallel flow arrangement has the advantage that it equalizes the heating eifect across the blanket, and also reduces'the pressure drop or resistance to liquid flow in the tubing 12, as comparedwith a series path through a single tube looped back and forth across the entire blan ket.

it has been found preferable to use small diameter tubing throughout the entire blanket and to connect this 7 tubing to small compact headers or junction units 16, 18

rather than having large diameter header tubes extend along the edge of the blanket.

enough in diameter to carry the liquid for substantially all of the circuits 12 without appreciable pressure drop.

On the other hand, tubing of the required diameter is FIG. 10 illustrates a cooling and heating system emvery likely to kink and materially reduce or even com pletely cut off the flow of liquid if made flexible enough to conform to folds and the like in the blanket. The header units 16, 18 can be very compact assemblies, fully rigid to obviate kinking and yet extending over no more than one or two square inches of blanket surface area.

As shown in detail in FIG. 3, for example, each header unit may comprise a short length of metal tubing 20, partially fiattened to an oval shape throughout a portion of its length, and having the oval shaped end 26a sealed off. In the oval shaped portion of the tube 20, short stubs 24 of very small diameter tubing are soldered into the tube 2%) in the general plane of the major axis of the oval to connect to the blanket circuit tubes 12. The round end 29b of the header tube 2%? is adapted to be The arrangement is such that heated I The reason for this is that if long header tubes are used, they .must be large from some source such as an open flame 3d. The end of one leg of the U-tube 29 is connected through a smaller diameter U-shaped vapor transfer tube 32 to a vertical tube 34 which constitutes a vapor condenser chamber. The lower end of the condenser tube 34 and the other leg of the generator 29 are connected through a reservoir 36. The generator 29, the vapor tube 32, the condenser 34 and the reservoir 36 constitute a closed loop which is coupled to the blanket passages 12 through a pair of

check valves

37, 39, the

flexible tubing

26, 28, and the headers 16, 18.,

The operation of the thermopump 14 'is as follows:

When the heat of the flame Si) acts on the generator "tube 29 to vaporize the liquid therein, vapor will collect inthe upper portion of the U, raising the pressure in the pump and forcing liquid to flow downwardly through the leg of the generator tube and upwardly through the vapor tube 32 and the condenser 34. This, of course, 'will force liquid toflow out through the check valve 39 and into the blanket circuits 12 through the header to as the blanket circuits expand slightly to accept the liquid forced into them. When the liquid level in the pump has been .forced down by the vapor. to the lowermost point in the vapor tube 32, vapor will begin traveling up through the vapor tube 32. This will create a hydrostatic unbalance between the liquid inthe generator and condenser columns, tending to cause liquid to flow down wardly through the condenser tube 34 and upwardly into the generator 29. This counter-clockwise flow of liquid in the pump will force all the vapor out of the generator chamber andinto the condenser chamber wherein the vapor will condense,-thereby decreasing the pressure in the pump and causing liquid to be suctioned into the pump through the check valve 37 from the return header lidand the return tube 28. Thereupon, the system will temporarily come to rest until a new volume of vapor begins to collect in the generator tube, whereupon the entire cycle will be repeated. A more complete description of the features and functioning of the thermopump M will be found in the above mentioned Kleen patent.

From the brief description just given, it can be seen that the operation of the thermopump 14 will result in a continual cyclical delivery of hot vapor to the condenser tube 34-, and that during the expulsion stroke of the pump,

liquid heated by the vapor will be forced out of the condenser tube. If the volume of the coupling between the condenser 34 and the

check valves

37, 39 is less than that of the pump stroke, hot liquid will pass through the check valve 39 into the blanket inlet tube 26 on each pumping stroke. Thus, it can be seen that the therm'opump 14 is peculiarly adapted for utilization in a personal heating system of the type with which the present invention is concerned for the reason that the application of heat can be'utilized both to obtain the necessary circulating action and to heat the liquid being circulated.

While the flow of liquid to and from'the pump 14- is cyclical, rather than unvarying or continuous, the flexibility of the various tubes and tubing circuits is more than adequate to accommodate the small changes in liquid volume in the system outside the pump 14.

While the heat for generating vapor can be supplied in a number of different ways, a flame operated system is of particular utility for portable apparatus. So far as is known, the system of the present invention provides the first entirely practical portable individual heating or coolingapparatus to be proposed. For example, utilizing a fuel such as bottled propane gas or the like, readily 4 available in small containers occupying only a few cubic inches of space and weighing about one pound, a system of the type just described is ideally suited for individual use in cold areas. Such a system is particularly useful for evacuation of wounded military personnel from the field of action where weight and bulk of the protective apparatus must be kept at a minimum, and yet where some form of heating is frequently vital to prevent shock.

. Using a fuel supply of the type just indicated, it is entirely feasible to have a complete system capable of delivering 1500 Btu/hr. to the blanket for 10 hours and weighing less than 15 pounds, including blanket, pump and fuel.

f course, for heating applications in extreme cold, an anti-freeze liquid such as alcohol or the like will be used as the circulating medium. Water and other liquids are suitable in situations where the ambient temperature will permit use of higher freezing point liquids.

in domestic as well as military applications, sportsmen and others who haveoccasion to require some type of artificially supplied personal heating in remote localities Where electrical power is not available can use such an apparatus to advantage. Of course, while a bottled gas such as propane may be most convenient to use, other fuels such as wood alcohol, kerosene and the like can also With an electrically heated pump as shown in FIG. 4,

the apparatus of H88 1 and 2 has important advantages for use in the home. It is essentially noiseless in operation, and as compared with the conventional electric blanket it involves absolutely no risk of burns or electrical shock to the user.

As already indicated, the present invention is equally applicable to a personal heating unit in the nature of a suit or garment as well as the blanket-type heat exchange structure shown in FIGS. 1 and 2. The tubing lZ'can be sewn into such a garment as well as in a blanket. For example, as shown in FIG. 5, the tubing 12 can be arranged. in circuits through the body, arm and leg portions of a Coverall type garment 4b, with the pump and a fuel container assembled'in a cylindrical unit 42 hangrug from the garment 49 at the beltline. At least one of the tubing circuits 1?; normally will be provided in each portions of the garment 40,.with the of the arm and leg circuits 12 preferably being connected in parallel between inlet and

outlet tubes

26, 28. Of course, a greater number of circuits 12 can be provided for more uniform heat distribution if desired.

FIG. 6 is asomewhat enlarged view of the pump and fuel container assembly 4 2 of FIG. 5. As shown in FIG. 6, the upper portion of the assembly 42 comprises a cylindrical shell 43 housing the pump 1 (not shown in FIG. 6) and having a flue outlet opening 44- in the upper end through which to discharge exhaust gases from a burner 46 in the lower part of the shell The burner 46 is coupled to a cylindrical fuel container 48 by means of a threaded cap 50 in the bottom of the shell 43 into which the fuel container 4-8 can be screwed readily for quick interchange of fuel cartridges. A control knob 52. is mounted on the upper end of the housing 43 beside the flue outlet 44 for adjusting. the burner out- If the pump in FIGS. 1-4, and including thermopump. v

in the, FIG. 7 apparatus, there is provided a fuel container 48, containing a combustible gas such as propane or the like; On the outlet line frornthegas container 43, there is provided a pressure regulating valve 49 for eliminating fuel pressure variations due to ambient'temperature variations and the like.

ally controlled valve 51, operable by a control knob 52, for adjusting the flow of fuel. The valve 51 connects to a burner nozzle 46 which is disposed in the lower end of a flue' 44. s

Extending late-rally into-the flue 44 immediately above the burner 46 is the vapor generator tube 62 of a thermopump 16a certain features of which are described and claimed in a copending application of R. Coleman, filed July 5, 1952, Serial No; 297,371, and assigned to th assignee of the present invention.

The lower end of the generator tube 62 is connected to a generally vertical cylindrical tube 66 which comprises a combined reservoir and vapor collecting chamber. The upper portion of the generator 62 is of inverted U-shape and opens into the top of the vapor collecting chamber 66 at a point slightly off center.

In the center. of the top of the vapor collecting chamber 66, a vapor outlet tube 68 protrudes down into the chamber 66 for a short distance, and extends from the chamber 66 to a condenser tube 76 in a manner similar to the vapor tube 32, in the pumpwll l of FIG. 1.1 The condenser chamber 76 is connected at the bottom to the chamber 66, :while the top of the condenser tube 70 is coupled through a check valve 39 to a heat exchange 76 comprising a coil of several turns around thefiue 44 in the vicinity of the generator arm62. It will .be understood that the free end of the coil '74 will be connected to a header (not shown in FIG. 7) such as the header 16 in FIG. 1. Similarly, a return line 23 from a second header (not shown in FIG. 7) is connected to the condenser 70 through a second checkvalve '37. I Inside the vapor collecting chamber 66; there is provided a float 76 which will rise and fall in the chamber 66 as vapor is alternately collected in and discharged from the chamber 66. I a The system shown in FIG. 7 will be put in operation by igniting the burner 46 to provide a flame inside the flue 44. The flame will envelope the generator 62'and at thesame time supplyheat to the heat exchanger coil 76. Vapor generated in the generator 62 will pass over into the top of the vapor collecting chamber 66 and accumulate therein, at the same time for'cing'liquid downwardly in the chamber 66 and up and out through the condenser tube 70. Prior to vapor accumulation, the float '76 will perform one of its functions; i.e., preventing the flow of heated liquid up and out through the vapor tube 68, prior to collection of vapor in the top of the chamber 66. I

As vapor continues to collect in the collector 66, the liquid level therein eventually will drop sufficiently to allow the float 76 to drop away from the vapor tube 63. Thereafter, as further quantities of vapor are collected in the collector 66, the float '76 will act'as an insulating separator, reducing heating of the liquid to prevent overheating of the pump system.

Whenthe level of the liquid in the chamber 66 drops below the lowermost point in the vapor tube 68, the pump will cycle in'the same manner already described in connection with pump 14 in FIG. 1. However, it is to be noted that as the liquid level rises in the chamber 66 during the condensing or suction portion of the pump cycle, the float 76 will seal offthe vapor outlet tube 68 before liquid has completely refilled the chamber 66. This tends to maintain a quantity of vapor in the top of the collector 66 at all times, thereby facilitating the start of the next expulsion or pressure stroke of the pump.

a slightly modified type of" Downstream from the. pressure regulating valve &9, there is provided a manu It will be understood that by adjusting the control knob 52, the amount of heat supplied to the pump can be adjusted as required, simultaneously changing both the pumping rate and the amount of heat put into the pumped liquid at the heat exchanger coil '7 4. While the heating of the liquid within the pump itself is adequate for moderately low ambients, the heat exchanger 74 is advantageous for operation under extreme cold conditions.

As an alternative to the manual control of heating illustrated in FIG. 7, it is quite feasible to have thermostatic control of the pump operation orof the temperature of the circulated liquid. In other words, the temperature of the liquid being circulated can be thermostatically controlled without altering thepump output, or both the pump output and liquid heating can be controlled automatically by use of a thermostatic valve supplementing or replacing the manual valve 51 in FIG. 7.

For example, as shown in FIG. 8, the manual valve 51 of 'FIG. 7 can be replaced by a thermostatic fuel control valve '78 disposed in the return line 28 to be bathed by and responsive to the temperature of the liquid returning from the blanket through the tube 28. This, of course,

I tively remote-- from the body-covering area.

will control pump output and liquid heating simultaneously. Alternatively, as shownschematically in FIG. 9, the heat exchange coil '74 of FIG. 7 can be connected in parallel with a bypass line 74a to a two-way thermostatic liquid floW control valve 3% disposed in the return line 28 to be bathed by the return fluid from the blanket: In this case, the thermostatic valve is arranged to directmore fluid through the by-pms 74a and correspondingly less through the heat exchange coil '74 as the temperature of the returning liquid from the blanket increases. Of course, a combination of both types of control illustrated in FIGS. 8 and 9 is entirely feasible.

As previously indicated, the apparatus of the present invention can be used for personal cooling as well asv for heating. In the apparatus of FIG. 1, for example, if the volume of the coupling between the condenser tube 34 and the check valves 37, 39' is greater than the volume of one stroke of the pump 14, it istlieoretically possible to'keep hot liquid from passing the outlet check valve 39. Under these conditions, liquid will be circulated through the circuitslZ in the blanket 8 without any heating by the pump. The circulating liquid will, however, absorb.

hcat'from a person covered by the blanket, and this heat will be lost. as the liquid circulates through circuits rela- Thus, a definite cooling action will be obtained even though the temperature of the circulating medium is not artificially forced below the ambient temperature. in fact, experiments show that circulating a liquid at temperature only a few degrees below the ambient may create a definitely uncomfortable chilly condition, if the area of body contact is at all extensive. v 3

Investigation also has shown that there is a psyochological factor involved in cooling that has bearing on the apparatus used for cooling, and the Way in which it is used. This is based on the fact that the average individual is accustomed to having his head exposed and the rest of his body covered. This means the individual is also accustomed to a slightly higher ambient temperature close to the body below the neck as compared to a similar area" about the head. It has been found, therefore, that a cooling blanket, while cooling the body, is not necessarily the only satisfactory cooling medium, because as long as the head is cooled even slightly,iit is found that one can be quite comfortable on a very warm night. In other words, a satisfactory cooling effect can be obtained with a cooling pillow-under'the head as well as with a cooling blanket over or under the body. Experiments have shown that a person using a cooling pillow as contemplated herein can be quite comfortable under a light blanket when the room temperature is such that the sameperson feels uncomfortably warm without the cooling pillow, even though completely uncovered.

' system arranged in accordance with the invention.

and 2 construction.

It should also be noted that a cooling device of the type about to be described is not necessarily limited to use of a thermopump as the liquid circulator, since a mechanical pump can be used that is arranged to circulate liquid through the cooling circuit Without atiecting the temperature of the circulated liquid. -Iowever, the use of a thermopump is deemed preferable since it is essentially noiseless, is less expensive, requires less maintenance, and can also be used for a combination heating and cooling system.

- In FIGS. 10 and 11 there is shown a personal cooling ihe same apparatus can also be used for heating, as willbe explained shortly.

The apparatus shown in FIGS. 10 and 11 includes a thin, flexible heat exchange structure 31 comprising two superposed flexible sheets 32, $3 of water-proof material, having approximately the (rectangular) dimensions of an ordinary bedpillow. The

sheets

82, 83 preferably are of plastic material, such as one of the so-called vinyl plastics. The'two sheets 82, 33 are sealed together along the edges and along spaced lines 84- to define in the unsealed areas between the

sheets

82, 83 integral passages 86 through which to circulate cooling liquid.

Even though the coolingelernent (ll of FlGS. 10 and 11, when used in the manner described hereinafter, will tend to keep the user comfortably cool, it is possible for small quantities of moisture to accumulate under the users head and create a clarnmy feeling. Accordingly, in the sealed surface'areas 84- between the conducting passages $6, the cooling element 81 preferably is perforated as indicated at so that moisture will not accumulate on the waterproof surface (32 or 83).

In the cooling element presently being descnibed, as compared with the blanket structure of FIGS. 1 and 2, it is seen that the passages 86 are arranged in a continuous circuit between the inlet and

outlet tubes

26, 28, rather than all in parallel as are the tubes 12 in the FIGS. 1 The reason for this is that in the system of FIG. 10, heat exchange bet een the user and the circulating liquid is more a matter of conduction than of convection. In other words, it is contemplated that the user will lose heat to the surface of the cooling element ill by contact therewith (with, perhaps, a pillowcase or the like separating the users head from the cooling surface). Accordingly, for best efiiciency; the circuit 86 should be arranged so that no matter how limited the area of user contact, substantially all of the cooling medi' um will flow through that area. In the case of the heating blanket, on the other hand, what is contemplated is the creation of a warmambient about the users body, rather than direct heat exchange contact between the users body and the warm surface. Therefore, it is not essential that the warming liquid flow through every one of the blanket circuits to every portion of the blanket, but merely that the heated liquid flow through a major part of the blanket to create Warmth beneath the blanket which will dispel itself over the entire area covered by the blanket.

Secondly, if all of the passages in the cooling element 81 were connected in parallelbetween the inlet and

outlet tubes

26, 28 the pressure of the users 'head might well divert all of'the cooling flow through passages remote from the users head, and the cooling efiect would be lost. 0f course, it is entirely permissible to have two or more parallel circuits through the cooling element, provided valve 94 that permits the user'to select either the long line id or the short line 92 as the coupling, as explained hereinafter.

In use, it is contemplated that the cooling device 31 will be inserted between the pillow body and the pillo case of an ordinary bedpillow. Assuming that the valve he has been set as in FIG. 10 to complete a circuit to the pump through the line and with the entire system of FIG. 10 filled with liquid, such as water, operation of the thermopump 14 will establish a cyclical flow of liquid back and forth in the line 90. This will force liquid through the check valve 39, around through the passages 86, and back through the check valve 37 as the liquid moves back and forth in the isolation line 90. As the liquid passes under the users head, it will absorb heat, and will thenlose this heat during circulation through parts of the element 8d remote from the users head and through the

coupling lines

26, 28. The relatively large volume coupling line 90 will ensure against any transfer of heat from the pump to the cooling element 81.

In order to use the apparatus of FIG. 10 as a heating system, the valve 94 will be adjusted to place the short line 92 in the circuit rather than the long line 94. This will couple the pump 14 closely to the element 81 so that, on each pump stroke, heated liquid will flow from the pump 14 past the check valve 3h and into the passages 86.

Due to the flexibility of the element 81, it is possible that the weight-of a users head may materially restrict one or more of the passages 8-6, cutting down the flow of cooling fluid. This effect can be substantially overcome by charging the system with fiuid at a pressure slightly above atmospheric pressure to help maintain the cross-' will not have the benefit of drawing in relatively cool liquid 1 on such suctionstroke. Depending on the'heat loss characteristics of the coupling line from the condenser to the check valves, it is possible for the condenser to overheat under these conditions so that the thermopurnp will fail to operate due to failure of condensation.

'Again, it is sometimes found that when the cooling element 81 is inserted in a pillow as just described, the pillowcase does not allow enough heat loss from the circulating liquid to obtain the desired cooling effect.

To avoid these difficulties, auxiliary cooling circuits both for the pump and for the cooling element sometimes can be used toadvantage. I An arrangement illustrating the use of such auxiliary cooling circuits is shown in FIG. 12. The FIG. 12 system also includes a preferred form of cooling element, as well as a circuit arrangement that all of the circuits are substantially coextensive and all pump 14 and the check valves 37, 3%, through a selector cooling, as desired.

In the PEG 12 apparatus, a thermopump 14 is connected to circulate liquid through a heat exchange element 81a. Between the pump 14 and the element 81a in FIG. 12, there is provided an auxiliary cooling or isolation circuit for the pump 14, comprising a tube 96 and a pair of check valves 98, 1%. Between the check valves 98, 1653a T connection 162 leads to the cooling element circuit through an isolating line 104.

To provide extra cooling for the liquid circulated through the element 81a, the system of FIG. 12 includes a pair of relatively long inlet and outlet lines 26a, 23a, rather than the comparatively

short lines

26, 28 utilized in the FIG. 10 system.

The cooling element 81a in FIG. 12 is made up in a manner similar to that shown in FIG. 11; e.g., by sealing.

cuit arrangement is somewhat different. In the FIG. I element til, it will be. noted that the. circuit extends from the corner where the liquid inlet 26 is located, to the diagonally opposite corner, along a devious path that extends backand forth across the element 81, and then returns directly along the edge of the element to the outlet opening connecting with tube 28.

If. the element 81 is contacted by the users head'in any given area, the surface downstream from that area-will contain relatively warm liuid, while upstream fromthat area the liquid will be cool incoming liquid. Thus, a fairly well defined separation will exist between the warm and the cool surface areas. Experiments have shown that this is not entirely desirable. Since the cooling effect or distribution of cool liquid is not uniform across theelement 81, there is a tendency for the used to move about restlessly in an attempt to use only the coolest part of the,

element. in order to overcome this tendency, it has been found desirable to distribute the circuits in such a manner that passages containing relatively cool incoming liquid will be intermingled with passages containing outgoing relatively Warm liquid, so that the relatively warm and cool liquid areas will not be sharply separated but will be mingled in such a manner that the user will not'prefer one area of the element to another.

A preferred circuitarrangement for accomplishing this is shownin the element dla in FIG. 12, wherein subscripts ap have been added to the passage numerals $6 to facilitate discussion. i

To avoid confusion, it should be noted first that the passages dam-85p are connected together to form two substantially identical circuits extending between the inlet and outlet connections 260., 2.8a. This'has the eifect of decreasing the pressure drop orresistance to flow through i the cooling element for a given flow rate. For simplicity, in the following discussion, it will be assumedthat only a single circuit is involved.

Starting from an origin point at the inlet tube 26a, in the upper lefthand corner or" the element 31a as viewed in the drawing, the circuit extends along a devious path through passages 3611-4365 traversing substantially the However, with the circuit arrangement shown, wherein the circuit is, so to speak, folded back on itself, the paralleled incoming and outgoing liquid pathswill distribute the cooling effect more uniformly and across a greater part of the element'hlra than in the case of the circuit in the element 81.

While the foregoing discussion has been'directed-primarily to the case of a bedpillow type of cooling element, it should be noted that the invention is by no means thus limited. For example a larger element of similar construction can also be used for cooling, in the same mannor, as a mattress cover, an automobile seat cover or the like.

ing element circuit in FIG. 12 either directly, or through the isolation line Ell-t, by means of a selector valve 94, so that the heat exchange element 81a can be used either for heating or cooling. i

For example, if the FIG. 12 system is to be used for cooling, the selector valve 94 will be set in the position The pump 14 is arranged to be connected to the cool snares shown to couple the pump 14 to the element 81 through the isolation circuit 164. This will cause hot liquid forced from the pump 14 to llow past the valve 1%, and this hot liquid will cool considerably before being returned through the valve 93 several cycles later. As before, the

reciprocating motion of the liquid in the isolation tube of its heat, the auxiliary cooling circuit as, 98, we will not be needed.

A somewhat simpler substitute for the auxiliary cooling circuit )6ltlil of PEG. 12 is shown in FIG. 13.

This comprises a tank N6, of volume several times that of the pump stroke, in place of the tube 96 and check valves 98, 1%. The tank res also can serve as a collector for any air inadvertently trapped in the system when it is filled. In fact, a small quantity of air can purposely be'trapped in the tank res, both to serve as a cushion for absorbing the pump stroke if the cooling circuit is inadvertently kinked off, as well as a thermalisolator for reducin the required volume of the isolation line'ldd. In operation, the hot liquid discharged from the pump will rise to the top of the tank 1% on each pressurestroke, while on the suction stroke the pump will refill with relatively cool liquid from the bottom of the tank. At the same time, any air in the system will gradually work its way to the highest point in the tank where it will collect and serve the cushioning and isolation functions already stated. l a

If desired, the control valve $4 in the systems of FIGS. 10-13 can be in the form of a thermostatic valve, arranged as shown in FIG. 14, to hold the maximum temperature of the circulated'liquid at some preselected level. The thermostatic valve 108 is placed in theoutlet line 28a to sense the temperature of the liquid leaving the heat exchange structure 81a. With such an arrangement, an increase in the temperature of the liquid leaving the element 81a will. cause the valve 1% to divert some of the liquid leaving the pump 14 to flowv through the isolation circuit %I1tl, thereby decreasing the heat input to the element Sta. In warm weather, of course, the thermostatic valve 198 will automatically divert all of the pumped liquid to flow through the isolation circuit h l'lltl, 'thereby'setting the system for cooling action as previously described. v

We claim: V

1. A quiet-operating personal thermal system utilizing circulating liquid comprising a thin, flexible, neat exchange structure adapted to be placed in thermal contact with a persons body and including means defining liquid conducting passages extending throughout said structure and having inlet and outlet ports, a heat actuated pump, and supply and return liquid-conducting means coupling said pump to said inlet and outlet ports respectively to circulate liquid through said passageasaid pump including a supply check valve in said supply liquid conductiug means to said inlet port and a return check valve in said return liquid-conducting means from said outlet port, a vapor generator chamber in which to form vapor by eating whereby to force liquid out of said pump due to displacement of liquid by vapor, means for heating said vapor generator chamber, a vapor condenser chamber in which to condense vapor generated in said generator chamber whereby todraw liquid into said pump to replace the condensed vapor, and a vapor transfer passage between said generator chamber and said condenser chamber. The inventiondefined in claim 1 wherein said heat exchange structure comprises a fabric blanket having a plurality of liquid-conducting flexible tubes disposed in said blanket, each of said tubes having one end connected to said inlet port and theother end connected to said outlet port, whereby all of said tubes are connected in parallel liquid-conducting relationship, each of said tubes being bent back near its center with its two halves extending along closely adjacent to each ot rer so that the liquid flows in opposite directions through the two adjacent halves of the tubes, thereby to provide a uniform average temperature along each tube, and said tubes being substantially uniformlyspaced throughout said blanket to provide a uniform heating effect throughout thearea or the blanket. 3. The invention defined in claim 2, wherein each said tube makes a single pass' along a first path from one edge of said blanket to thev opposite edge and then ret ms to said one edge along a path closely paralleling said first path. n 4. The invention defined in claim 1 wh rein said heat exchange structure comprises superposed sheets of flexible, water'proof, heat-scalable material, said sheets being sealed together along spaced, finite abutting areas to define liquid conducting passages through the unsealed area between said sheets, said'sealed areas being substantially equal in width to the widths of the unsealed areas therebetween.

5. A personal thermal system adapted for use with a circulatin liquid com rising a thin, flexible, heat exis i P I to form vapor by heating whereby to force liquid out of said pump due to displacement of liquid by vapor, said generator chamber communicating with said inlet tube,

said displaced liquid flowing from said pump to said heat.

exchange structure through said inlet tube, and a vapor condenser chamber in which to condense vapor generated in said generator chamber, said condenser chamber communicating with said outlet tube, whereby to draw liquid into saidpump through said outlet tube to replace the condensed vapor, means for heating said vapor generator chamber, and said inlet tube having a portion arranged in heat exchange relation with said heating means, said heating means supplying the energy to pump the liquid and also to heat the liquid.

6. The invention defined in claim 5 and further including a by-pass tube connected in parallel with said heat exchange portionof said inlet tube, valve means for controlling the relative flow through said by-pass tube and through said inlet tube portion, and a temperature-responsive control coupled to said valve means and being at least partially responsive to the temperature of the liquid returning from the outlet port for controlling said valve means in response to the temperature of the liquid returning from said heat exchange structure.

7. The invention defined in claim 5, and including means for regulating the amount of heat supplied by said heating. means to said vapor generating chamber, and a thermostatic control connected to said regulating means, said thermostatic control being at least partially respon- V sive to the temperature of the'liquid flowing through said outlet tube for controlling the amount of heat supplied to said vapor generating chamber.

8. The invention defined in claim 5, wherein said heating means comprises a fluid fuel burner, a bottled-gas fuel supply source connected to deliver fuel to said burner, and a thermostatically controlled valve forv regulating the flow of fuel from said supply source to said burner, said thermostatically controlled valve being at least partially.

responsive to the temperature of the liquid returning from said outlet port.

9. A bed covercornprising va flexible layer of fabric,

I12 means defining a plurality of flexible fluid carrying assageways within said fabric, a totally enclosed pump unit remotely disposed relative to said bed cover, flexible conduit means interconnecting said pump unit and said passageways, a heat transfer liquid circulated through said passageways by said pump unit, means for varying the temperature of said heat transfer liquid, and means responive directly to the temperature of the liquid return- =from said flexible fluid carrying passageways for con trolling said means for varying the temperature.

10 A bed cover comprising aflcxible layer of fabric,

meansdefining a plurality of flexible fluid carrying passageways associated with said fabric, fluid circulating means remotely disposed relative to said bed cover for sageways associated with said fabric, a fluid circulating element remotely disposed relative to said bed cover for circulating a heat transfer liquid throughsaid passageways, flexible conduit means interconnecting said fluid circulating element and said passageways associated with said fabric, temperature responsive means responsive directly to the temperature of the heat transfer liquid returning from said flexible fluid carrying passageways, a temperature varying element for varying the [temperature l of said heat transfer liquid, and means responsive to said temperature responsive means for controlling one of said elements.

12. A heat exchange blanket adapted for use in main taining a persons body at a comfortable temperature com, prising a generally rectangular fabric, a pair of small header units in said fabric near one of its edges and forming liquid inlet and outlet ports for said blanket, a plurality of long liquid-conducting flexible tubes of capillary dimensions each connected at one end to the inlet header and at the opposite end to the outlet header, said tubes being in parallel liquid-conducting relationship between said inlet and said outlet headers, each said tube being bent near the center of its length 'at a bend forming the tube into a pair of closely adjacent parallel tube sections of substantially equal length with liquid flow through the adjacent sections of each tube being in opposite directions, said tubes being positioned in said fabric with said bends adjacent the opposite edge of the blanket from said headers, said bends being spaced at substantially uniform intervals along said opposite edge with the adjacent parallel sections of .each tube extending [from the bend in spaced parallel relationship across the fabric to the edge near said headers and thence turning and extending along the latter edge to the headers, whereby said blanket is maintained at a uniform temperature throughout,

13. A thermal blanket comprising two superposed layers of fabric material, said layers being secured together along spaced parallel lines defining a plurality of spaced parallel pockets extending a substantial distance across said blanket between a pair of opposite edges, a pair of small header units extending between said layers near a first one of said edges and centered along said firs-t edge,

said header units being positioned near each other and forming liquid inlet and outlet passages, a plurality of long flexible small-diameter tubes, each of said tubes being connected at one end to .the inlet header and at the other end to the outlet header, said tubes being in parallel liquid-conducting relationship between the inlet and outlet header, each of said flexible tubes near its center the two halves of the tube forming a pair of closely adja- 7 tioned in a pocket, with the respective bends of said tubes all being near the second edge of said blanket, said closely adjacent parallel sections of tube extending back along the respective pockets in spaced parallel relationship to said first blanket edge and thence along said first edge to said headers, whereby the blanket is maintained at a uniform temperature throughout.

14. A thermal blanket adapted for use in maintaining a comfortable uniform, temperature adjacent to a persons body and including a fiabric panel having a plurality of tubular passageways therein, said tubular passageways comprising an inlet port and an outlet port, liquid supply means and liquid return means along one edge of said fabric panel and being connected to said inlet port and said outlet port, respectively, and a plurality of liquidconducting flexible tubes each connected at one end to said liquid supply means and each connected at the other end to said liquid return means whereby all of said tubes are 'connected in parallel liquid-conducting relationship between said liquid supply means and said liquid return means, each of said tubes being bent back adjacent to itself in a U-shaped bend near its middle forming a pair of adjacent parallel tube sections having liquid flow therethrough in opposite directions, said U-shaped bend-s being uniformly spaced along the opposite edge of said fabric panel from said liquid supply and return means, the parallel sections of all of said tubes being disposed in spaced parallel relationship extending across said fabric panel, whereby even though a substantial temperature differential exists between the fluid entering and leaving said tubes, the average temperature produced by said parallel adjacent tube sect-ions is equal throughout the extent thereof, whereby said fabric panel is maintained at a uniform temperature throughout.

15. A heat exchange blanket adapted for use in maintaining a uniform temperature adjacent to a persons body comprising an area of flexible material having a plurality opposite directions, the pair of equal-length sections of each respective tube lying closely adjacent to one another, whereby the liquid flowing through each tube to its U- shaped bend and returning through each tube from its U-shaped bend travels along closely adjacent paths throughout the length of the tube, whereby even though a substantial temperature differential exists between the temperature of theliquid entering and leaving said tubes, the average temperature produced by the adjacent equalleng-th sections of said tubes is equal throughout the length thereof, whereby said area of flexible material in the blanket is maintained at a uniform temperature throughout.

16. A flexible thermal panel adapted for maintaining a uniform temperature adjacent to the human body comprising an area of flexible material having a plurality of parallel connected fluid-conducting passageways disposed therein in substantially uniformly spaced relationship throughout said area, each of said passageways doubling back upon itself at a point midway of its length, the two halves of each passageway being closely adjacent one another thoro'ughtout their lengths, whereby the fiuid flowing into each passageway to the point midway between its ends follows a path which closely and con tinuously parallelsthe path of the fluid flowing (from said point out of the respective passageway, whereby even though a substantial temperature differential exists between the temperature of the fluid entering and leaving said passageways, the average temperature produced by the adjacent halves of each passageway is equal through outthe extent thereof, whereby said panel is maintained at a uniform temperature throughout,

References Cited in the file of this patent UNITED STATES PATENTS 719,638 Batter Feb. 3, 1903 1,121,277 Mitchell Dec. 15, 1914 1,896,953 Hassell Feb. 7, 1933 2,015,240 Scott-Snellet al. Sept. 24, 1935 2,062,864 Clark et a1 Dec. 1, 1936 2,110,022 Kliesrath Mar. 1, 1938 2,155,510 Shepperd Apr. 25, 1939 2,250,325 Barnes July 22, 1941 2,397,232 Barnes et al. Mar. 26, 1946 2,400,290 Clancy May 14, 1946 2,402,413 Kogel June 18, 1950 2,504,308 Donkle- Apr. 18, 1950 2,553,817 Kleen May 22, 1951 2,615,115 Wat-ter Oct. 21, 1952 2,652,824 Kopp Sept. 22, 1953

Claims

1. A QUIET-OPERATING PERSONAL THERMAL SYSTEM UTILIZING CIRCULATING LIQUID COMPRISING A THIN, FLEXIBLE, HEAT EXCHANGE STRUCTURE ADAPTED TO BE PLACED IN THERMAL CONTACT WITH A PERSON''S BODY AND INCLUDING MEANS DEFINING LIQUID CONDUCTING PASSAGES EXTENDING THROUGHOUT SAID STRUCTURE AND HAVING INLET AND OUTLET PORTS, A HEAT ACTUATED PUMP, AND SUPPLY AND RETURN LIQUID-CONDUCTING MEANS COUPLING SAID PUMP TO SAID INLET AND OUTLET PORTS RESPECTIVELY TO CIRCULATE LIQUID THROUGH SAID PASSAGES, SAID PUMP INCLUDING A SUPPLY CHECK VALVE IN SAID SUPPLY LIQUID-CONDUCTING MEANS TO SAID INLET PORT AND A RETURN CHECK VALVE IN SAID RETURN LIQUID-CONDUCTING MEANS FROM SAID OUTLET PORT, A VAPOR GENERATOR CHAMBER IN WHICH TO FORM VAPOR BY HEATING WHEREBY TO FORCE LIQUID OUT OF SAID PUMP DUE TO DISPLACEMENT OF LIQUID BY VAPOR, MEANS FOR HEATING SAID VAPOR GENERATOR CHAMBER, A VAPOR CONDENSER CHAMBER IN WHICH TO CONDENSE VAPOR GENERATED IN SAID GENERATOR CHAMBER WHEREBY TO DRAW LIQUID INTO SAID PUMP TO REPLACE THE CONDENSED VAPOR, AND A VAPOR TRANSFER PASSAGE BETWEEN SAID GENERATOR CHAMBER AND SAID CONDENSER CHAMBER.