US2387258A - Thermal applicator - Google Patents

Description

Ot.q23, 1945. A. HAGUE THERMAL APPLICATOR Filed May 16, 1941 M/VEA/TOAZ ALF/250 H4605 Patented Oct. 23, 1945 V UNITE-D STATES PAr NroFFlcE THERMAL APPLICATOR Alfred Hague, ossining, N. Y. Application May 16, 1941, Serial No. 393,803 Claims. (c1. 128'403) This invention relates to thermal applicators used for heating or cooling purposes, and has for its object the provision of an improved thermal applicator and method of transmitting the therlost to the surrounding atmosphere by conduction through the material of which the bag is made. In an endeavor to reduce this necessity for frequent replenishment, particularly in the case of hot water, there is a tendency to supply the hot water at a temperature considerably higher than that required, with the danger of burning the patient unless the hot water bottle is wrapped in a towel or other insulator until it cools sufiiciently to be used directly, which common practice in turn involves unnecessary waste of the heat energy: Even where normally poor conductors of heat, e. g. rubber, are used in the fabrication of these appliances, the transmission by and loss of heat as a result of conduction is none the less vvery substantial. 1

I have found that this high thermal conductance and its attendant energy waste in the ordinary hot water or ice bag, proceeds to a large extent from the use of material therein, such as rubber and the like, which is relatively'highly absorptive of the long wave infra-red radiation principally characterizing these sources of therice bag, orother thermal applicator, is transmitted through a material which is substantially transparent to the infra-red radiation principally characterizing the hot water, ice, or other source of thermal energy, the term ,fthermal being used herein to embrace also, radiationwhich would in common parlance be designated as cold waves rather than heat Waves.

In the accompanying drawing I have shown certain illustrative embodimentsof my invention, and referring to the same:

Fig. 1 is a sectional front elevation of one form of appliance taken along the line l-l of the appliance shown in sectional side elevation in Fig. 2.

Fig. 2 is a sectional side elevation taken along the line 2-'-2 of the appliance shown in sectional front elevation in Fig. 1.v

mal energy. As a consequence of this high absorption of the radiant thermal energy emanating from the source, it is inevitably transmitted by conduction, regardless of the otherwise poor ther-' mal conductivity of the material, and the ultimate eifect secured is. substantially an absorption, a conduction, and to a reduced extenta re-radiatlon of the radiant thermal .energy with altered wave length by the materlalforming the exposed surface, with proportionate increase in the amount of heat lost to the convection currents set up in the atmospheric air in contact with said surface. In other words, the principal function which the internal source of radiant thermal energy in these appliances actually serves, is simply to heat up the outer walls of the appliance which are in contact with the outside atmosphere.

In accordance with my invention, the radiant energy from the source within the hot water or Fig, 3 is a mid-sectional front elevation of a modified form of structure, which would appear the same in mid-sectional side elevation.

Fig. 4 is a mid-sectional elevation of a further modified form.

Referring to the drawing, and in particular to Figs. 1 and 2, reference numeral l 0 generally designates a thermal applicator, such as a hot water bottle, which comprises a hollow shell ll constituted of an outer wall l2 and an inner wall I 3 defining a space M. For convenience in manufacturefthe shell may if desired, be made in two maior sections A and B, suitably connected together by cementitious material, fusion or the like along the bisecting line I5; the outer wall of the upper section B being designated l2, the inner wall l3, and the space between them I 4. Access to the interior I6 of the shell I l is afforded by the tubes l1 and I8. A casing I9 of copper, gold, or other suitable metallic or other material, covers th upper part of the shell and is provided internally with a surface 20 which is suitably reflective of the infra-red radiation emanating from the source of thermal energy contained in the interior Hi. This casing, and if desired, the coordinate upper section B of the shell also, may be parabolic or of any other suitable form.

With the exception of the casing IS, the shell H, as shown, is made of amaterial 2| which is substantially impervious to the fluid or other tan-v gible medium with which it will ultimately be in contact, but which is substantially transparent to the long wave infra-red radiation which principally characterizes the particular source of thermal energy involved.

Where the appliance is used as a hot water bottle, for most practical purposes the temperature of the water supplied thereto can be considered to range from a maximum of about 212 F.

downwardly to 118 F. or somewhat less, which minimum is still sufiiciently above the normal body temperature of 98.6 F. to provide sensible heat, i. e. heat which can be perceptibly felt by the human body. At 212 F, the wave length of maximum radiation characterizing the spectral distribution of energy at this temperature, computed fort-thetheoreticalblaclrbody by means ,of' the well; known Winsdisplacement law, would. be approximately 77,000 Angstrom units and at 118 F. it would be approximately 90,000 Ange strom units. application of my invention, Wiens law can be" used as a guide in the selection of the infra-red,- transmitting characteristic of my, materials 2!.

For this hot water bottle type of application; fluorite (calcium fluoride) is one materialwhich; I have found to be highly effective for transmitting} the long wave" infra-red radiationl principally characterizin the distribution of spectral encrgyof' the hot water at the temperatures ordinarily utilized. This'm'aterial has-a low thermal conductivity and in a thicknessofapproximatelyyl 'cm. will transmit QVI' 8 5% of infrared' radiation shorter than 80,000'A; wave length, around 85% of 80,000 A1 wave length; and somewhat over'50% of 90",000A. wave length, which lattertr'ansmission can he stepped up'still further by suitably reducingthe 1 cm. thickness of. the material. Unless otherwise noted herein, the various percentages of'infra-red' transmissibility given, indicate the ratio of the transmitted. infra-red .to the incident infra-red for a thickness of approximately 1 cm. of the. transmitting material.

Other; materials. which. arelfhi'ghly. effective, particularly. where; wave, lengths materially long; er than 90,000 A. arecontemplated, are sylvine, (potassiumbhloride) androclilsaltxsodium chloride). These two materials are almost: perfectly transmissible (over- 90% of the infra-redupto atwaverlength of 140,000 A. .(wave length oimaxi-mum infra-red radiation: at at temperature of -&7- R), above whichlwave. length the transmissibility begins to drop? off. Thev water solubility problem. presented by these potassium and sodium chlorides can? be overcome by fabricating the: body 'of: the transmitting: material; of sylvine or' rock salt, and providing asuitably thinprotectivecoating: of the insoluble fluorite or: other suitable insoluble infra-red transmitting material, over-that area of'the; sylvineror rock salt which-would come in contact with water or. other solvent or disintegrating medium;

Where the-transmitting StructuresIequiredare not! unduly extensivei and may be cut or bored out from suitably large? pieces of the natural crystal, or assembled by: cementing or fusing together suitably pre -formed" smal-l piecesv suchas panes; tubes, etc., of: the same; vthermineral forms of fluorite, rock salt or: sylvine: desired; be used directlyas thebasla material; Otherwise, these compounds; amen asi the mineral or a manufactured product, maybe fus'ed; and then molded; pressed, rolled; blown, or" otherwise formedintothe desired? shapes; The; presence of color and low visible-lighttransmission in these materials, frequently "found in the mineral forms; is'of 'no particular moment so long'as-the infra-red transmitting properties are not seriously impaired'thereb e factthe material-can conceivably be perfectly" opaque to visible light For all practical purposesin the rays, provided its transmission efficiency for the infra-red radiation involved is suitably ig The various infra-red transmitting materials used in my invention, if desirable and if amenable to such treatment, may be ground into the form of lenses, to concentrate or otherwise regiment the radiation.

In another form of composition of the infrared transmitting material 2|, suitably small particles, crystalline. or otherwise; of fluorite or other infra-red transmitting material, may be incorporated in or deposited upon the surface of a suitable matrix or hinder, e. g. cellulose acetate or other suitable cellulosic compounds, suitable synthetic Or natural resins, and various other satisfactory plastics. The dispersion of the particles of the infra-red transmitting material withinthe matrix, may be accomplished by thoroughly; dispersing fine particles of the material in a solution of the matrix in a suitable solvent, 8; g., cellulose; acetate: in. acetone, and appropriately extruding; molding,' rollin or; otherwise treating the: dispersion, with evaporation. of; the solvent, to; iorrna suitably impervious pane, tube or other desirediorm: of: the finished material. Alternatively. the. infra-red transmitting particles; wh-icir may if desired'belarger than in the dispersion method, may be rolled or pressed into a suitably plastic mass or sheet of thematrix,

0 and the compositematerialthen formed into the desired shape and hardened by." drying. or other suitable treatment. With the provision of a suitably large quantity of' the" infra-red transmittingJparticIeS and thoroughdistribution of the a samein the matrix; the infra-red transmitting efiioiency of: such composite material may be madeitoiapproxiniate that of the dispersed material'itself. Where-it is desired to utilize rock salt; sylvine or: the like in this composite material, and therrocksaltorsylvine inthe resultant composite material is still materially accessible toisolvent; the composite material containing the rockisaltyetcz, may be provided upon its surface withi'a protective coating "film or pane of fluorite or other suitable: insoluble material. This "may be donezby. cementing a thin solid pane of pure fluorite,:.or fluorite in the compositeform with matrix, to the surface of'the composite rock'salt or sylvine material, or by applying a suitably plastic coating of'the fluorite in the composite form with matrix to'said surface and permitting ittoharden thereon. The protective coating of fluorite, or'fluoritein matrix, may be applied to a suflacer of the pure rock salt orsylvine in like manner. These various forms of infra-red transmitting material described herein may of course be utilized: in other applications where their spectral transmission or other properties or themethod of composing them, may be advantageous;

Thev hotwater bottle; or icepack or other appliancemaybe constructed in whole or in part ofany-of the specific forms of infra-redtransmitti'ng material'noted, either alone or in vari- OHS'ICOmbihatiOUS withthe other forms of-said material.

The spaces i4, i4, defined'by the outer walls [2, IZ-f'andthednner walls [3, l3 respectively, of" the sheili H are preferably hermeticallysealed and define a* rarefied atmosphere, rarefied? in the sense that the atmosphere may be constituted'of air'or any other suitable gas which is substantiallytransparent to the infrared =radi= ationinvolved, but which is suitablynon-con- I ductiveand non-convective of thermal energy from the inner walls I3, I3 to the outer walls I2, I2, either normally'or with suitable evacuation. This atmosphere should preferably; be relatively'free from. any material amount of suspended foreign particles, e. g., dust, vapour, water and the like, which would have a tendency to absorb infra-red radiation'in its transit .andact as heat conductors through the spaces: I I- M.

If necessary or desiredfthe atmosphere in either or both of the spaces l4, I4 may be evacuated to such a degree as to leave insufiicientresidual gas in the space to afiord any objectionable' 'degree of heat exchange by conduction or convection between the inner and outer walls through the space. Likewise, the atmospherein. either of the spaces I4, l4 may be evacuated to a greater degree thanthe other, as for example, to a greater degree in I4 where the section B is to hem close proximity to the'body of a patient. This evacuation can be accomplished by perforating the shell and sealing the orifice by fusion or otherwise after the evacuation.

The applicator I is designed for continuous .or intermittent flo-w therethrough of the fluid pro viding the thermal energy. For use with hot water for example, the tube Il may be connected by means of rubber tubing with a hot water faucet and similar rubber tubing connectedwith the outlet tube l8 for discharging the fluid,.said rubber discharge tube being provided with a suitable pinch cook or like device to restrict theflow sufficiently to keep the interior It of the applicator substantially filled, or to periodically out ed the flow. Similarly, one of the tubes H or I8 may be plugged, or dispensed with, and continuous or intermittent flow provided through the other tube in the manner of the applicator of Fig. 4. Where continuous or intermittent flow is not desired, either tube I! or I8 may be plugged with a removable stopper, the applicatorfilled with the thermal medium through the open'tube, and said inlet tube then similarly plugged.

In the operation of the applicator II], the infrared rays emitted downwardly from the thermal medium, will pass through the inner wall l3; the

rarefied atmosphere in the space I4, and the outer wall I2, and thence; through any intervening atmospheric air, directly to the area of application on a human or other body of matter being treated. This direct transmission is unaccompanied by any material absorption or convection loss in transit. The rays directed upwardly will pass through the inner wall I3, the rarefied atmosphere 'I I',"the outer wall l2, and Will then be reflected back into the interior I6 by the reflector surface on the interior of the casing I9, which casing is covered externally with suitable heat insulating material (not shown). This reflection of the rays, permitting their escape into the outside atmosphere only through the bottom of the applicator, is likewise unaccompanied b any material absorption of the infra-red radiant energyand its transmission and loss to the outside-atmosphere by conduction and convection. Such channel of conduction to the outside as might be afforded by the inner walls I3 and I3, which are in direct contact with the source ofthermal energy, is substantially blocked off by the non-conductive and non-convective rarefied atmosphere in the spaces I4 and I4. takesplace through the structures connecting the inner walls I3, I3 with the outer walls I2, IT is not great, and even this may-be substantially reduced by eliminating the partitions between the spaces I4 and I I in the illustrative two section The conduction which assemblys'hown, and restricting the connection between the inner and outer walls solely to the tubes ll and I8. With further restriction of the inter-connecting structure to a single tube, as in the provision for continuous flow'through simply one tube, the escape of thermal energy to the outside by conduction through the connecting structure, is rendered practically negligible.

Where the application of the thermal energy is one involving temperature elevation, utilizing for that purpose a heating fiuid such as hot water, oil, steam, or other liquid, vapor or gas, suitable infra-red transmitting material ,ZI is ordinarily provided by the fluorite in any of the forms noted hereinbefore. The rock salt or sylvine materials may however be used if desired, in the solventproof form described if such is called for. Where, on the other hand, the application of the thermal energy involves temperature reduction, utilizing for that purpose a cooling fluid, such as suit.- ably chilled water, brine solution, or the like, the rock salt or sylvine forms of "the material 21, solvent-proofed if necessary, are more effective, because of their much higher transmissibility of the wavelengths of infra-red radiation predom inating at such low temperatures. In Fig. 3 I have shown a modified form of applicator 38, comprising an upper shell section 3I having an inner wall 32 and an outer wall 33, and a bottom shell section 34 having an inner wall 35 and an outer wall 36. The walls 32, 35 and 36 are made of the infra-red transmitting ma terial 2| described hereinbefore. The outer Wall 33 of the upper section 3| may be constituted of any suitable heat insulating material, and encloses a reflector 31 of copper, gold or other suitable material having an inner polished reflector surface 33 which is suitably reflective of the infrared radiation involved in the particular application. A neck 39,made of hard rubber 'or other suitable material, affords access'to the interior 40 of the applicator and may be provided with threads 4! to retain a similarly threaded plug (notshown) to close the opening. If continuous flow through the applicator 30 is desired, the neck 39 may be fitted with an apertured plug of the nature shown in Fig. 4, to permit continuous or intermittent flow of fluid medium through the applicator. A space 42 is provided in the section 3 and a space 43 in the section 3I for the rarefied atmosphere described hereinbefore in connection with the applicator iii of Figs. 1 and 2. Where evacuation of the space 43 is contemplated, this will be facilitated by making the heat insulating wall 33, of material which can be effectively cemented, fused, or otherwise connected with the inner wall 32 to hermetically seal the space While I have shown the applicator 30 as substantially hemispherical in form, it may be semiellipsoidal, parabolic or of any other form desired.

In Fig. 4 I have shown another form of applicator 5|] substantially tubular in conformation, though it may be otherwise shaped,which comprises a shell 5| having an inner wall 52 and an outer wall 53 defining a space 54 for the rarefied atmosphere described hereinbefore. The shell 5| is constructed of the infra-red transmitting material 2I, and may be provided with a suitable reflector (not shown) around the outside or upon the inner surface, to direct the radiation as desired. The neck 55 of the applicator 5B is fitted with an apertured plug 56, of rubber or other suitable material, provided with an inlet tube 51 and an outlet tube 58: to; permitcontinuous or intermittent flow of thermal fluid through the interior 59 of. the applicator; If continuous or intermittent flowis not desired, an ordinary plug. can be substituted for the apertured plug 56.

The applicator 50 maybe tubular in form, substantiallydisc-shaped, parabolically or otherwise curved onits upper surface and: flat on the lower, or shaped in any other form dictated by the particular application-involved- Various changes may be made in the illustrative constructions'of applicators disclosed without departing from the: spiritlof my invention. They may, for example, be made either in one piece or as sectional assemblies of greater or fewer sections. Likewise, the reflector surface may be provided on any of the internal wall surfaces of the applicators, including the inner surface of 'thewall defining the interiors (16,40, 59). The outer surface of the reflector element may be isolated from the outside atmosphere by an interposed covering of suitable'heat insulating material, or said surface may be uninsulated' and coated with flat black paint, to absorb heat from the'surrounding atmosphere or translate absorbed light into heat, where such expedient will increase the thermal efficiency of the applicator. Where this external absorption isresorted to, the blackened surface should have access to the radiant energy from the outside atmosphere either directly, or relatively directly through suitable infra-red transmitting material, such as 2!. An illustration of such access would be presented by blackening the outer surface of the reflector 3! (Fig. 3), and either dispensing with the outer insulating wall 33 or making it of the material 2i; similarly, by blackening the outer surface of the reflector casing I9 (Fig. 1) and locating it on either the inner or outersurface of the inner wall [3, instead of externally of the applicator ID as shown. Conversely, where anice pack o similar low temperature application is involved, said outer surface of the reflector element, in the various locations noted, may be constituted of highly polished reflectivematerial to repel heat absorption by the reflector, rather than to promote it, with similar provision for its access to the outside atmosphere. For various applications, the double-walled or shell type of construction for the applicator may be dispensed with in whole or in part, and a single wall or transmitting pane used, with elimination of the rarefied intervening space. As illustrations, the lower section A of Fig. l, or 34 of Fig. 3, may be constituted simply of the single walls l3 and 35, respectively; or wall 53 of Fig. 4 may be dispensed with; or wall 32 of- Fig. 3; or both walls 32 and 3B of Fig. 3.

While I have made principal reference in the foregoing to the use of the customary hot water orice as the source of thermal energy in my applicators, other sources of the samemay be readily substituted therefor, in many cases with the attainmentof much greater efiectivene'ssthan in their usual methods of application. In general, the source of thermal energy may be either physi cal, chemical, or electrical, and for applicationo'f either sensible heat or cold. Suitable liquids include hot or cold water, oiLbrine' solution,.liquid carbon dioxide, etc. Likewise, hot or cold vapours or gases may be used, such as steam, air, or other denser gases. Hot or cold solidsmay alsobe used and specifically ice, so called Dry' his, solid carbon dioxide. etc. Exothermic chemical'reactions may be utilized, for example, hydration of an anhydrous material, and also endothermic reactime where such are suitably applicable. Simiilarly heat from an electrical resistance element may be used, preferably non-luminous to conserve the energy for heating, eg. by substituting an iron wire in the, rarefied" or inert space V 59,

These applicators and the method of transmission are adapted for a wide variety of uses, where the direct or indirect transmission of thermal energy to the human body or any other body of matter is involved.

For therapeutic uses they find a particularly effective application and may be used either externally of the human body or internally thereof. Their thermal transmission is not greatly diminished at a distance from the body, as is the case for example; with the ordinary hot water bottle which must inconveniently be kept in close proximity or contact therewith; and, moreover, when they are used in close proximity or contact with the body, the attendant discomfort is much less, due to the relatively slight'absorption of thermal energy from the inner source by their body-contacting walls. In addition more accurate control of the thermal application is made possible, and by suitable selection of the transmitting ma terial and the thickness of the same, certain wave lengths of infra-red radiation may be partially or substantially obscured from the body, for example cutting ofi 'wave lengths longer than approximately 93,000 A. in the heat treatment of the human body, this wave length representing the maximum radiation for the theoretical black body at 98.6 F.

In the case of cooling uses, with liquid carbon dioxide for example, or similar applications of cold to the body, my applicator is equally capable of transmitting the very long wave lengths of infra-red (sylvine transmits approximately 60% of the infra-red of wave length as long as 200,000 A.maximum radiation at temperature of 200 F.), and the conservation of such radiant ener y provided by my applicator against the otherwise enormous conduction and convection loss, without materially interfering with the application, is distinctly advantageous. Moreover, a relatively small amount of the shielded liquid or solid carbon dioxide or similar expensive freezing medium, can radiate over a much larger area of application, with proper direction of the rays as desired, than can be covered by actual physical contact of the medium with the'body.

The term screening with a medium non-absorptive of the radiant thermal energy or nonconductive of absorbed radiant thermal energy as used in the appended claims, is intended to include either partial or substantial or complete screening, as circumstances may render desirable, of the source of heat energy with avacuum, reflective material, or the infra-red transparent transmitting material, as well as other suitable media and various combinations of the same. some of which combinations are illustrated in the drawing.

I claim:

1. The method of applying thermal energy which comprises, screening a source of radiant thermal energy from convective or conductive matter externally thereof with a medium which is substantially non-conductive of absorbed radiant thermal energy froms'aid source to said matter, and passing infra-red radiation from said source to the subject of application through a solid material which is substantially transparent to wave lengths of infra-red radiation longer than approximately 50,000 Angstrom units and shorter than approximately 200,000 Angstrom units.

2. The thermal applicator which comprises, a source of radiant heat energy, means for screening said source from convective atmosphere externally thereof, said means being constituted of a medium which is substantially non-absorptive of the infra-red radiation from said source, and means for transmitting infra-red radiation from said source to a subject of application externally thereof, said means being constituted of material which is substantially transparent to wave lengths of infra-red radiation longer than approximately 50,000 Angstrom units and shorter than approximately 200,000 Angstrom units.

3. A thermal applicator which comprises a don-- ble-walled container for material emanating radiant heat energy, the walls of which are provided with a space therebetween and comprise a substance substantially transparent to wave lengths of infra-red radiations longer than approximately 50,000 Angstrom units, the space between the walls being substantially non-absorptive of the infra-red radiations emanating from the material and substantially non-conductive and non-convective of thermal energy from the inner to the outer walls.

4. A thermal applicator which comprises a double-walled container for material emanating radiant heat energy, the walls of which are provided with a space therebetween and comprise a substance substantially transparent to wave lengths of infra-red radiations longer than approximately 50,000 Angstrom units, the space between the Walls being substantially non-absorptive of the infra-red radiations emanating from the material and substantially non-conductive and non-convective of thermal energy from the inner to the outer walls, said infra-red radiation transmitting walls being composed of an infrared radiation transmitting substance selected from the group consisting of fluorite, rock salt and sylvine.

5. A thermal applicator which comprises a dou- =ble-walled. container for material emanating radiant heat energy, the walls of which are provided with a space'therebetween and comprise a substance substantially transparent to wa e lengths of infra-red radiations longer than approximately 50,000 Angstrom units, the space between the walls being substantially non-absorptive of the infra-red radiations emanating from the material and substantially non-conductive and non-convective of thermal energy from the inner to the outer walls, said infra-red radiation transmitting walls being composed of a matrix having incorporated therein particles of infrared transmitting material selected from the group consisting of fluorite, rock salt and sylvine.

ALFRED HAGUE.

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