CA1192803A - Heating device - Google Patents
Heating deviceInfo
- Publication number
- CA1192803A CA1192803A CA000415750A CA415750A CA1192803A CA 1192803 A CA1192803 A CA 1192803A CA 000415750 A CA000415750 A CA 000415750A CA 415750 A CA415750 A CA 415750A CA 1192803 A CA1192803 A CA 1192803A
- Authority
- CA
- Canada
- Prior art keywords
- heating device
- heat
- layer
- heating
- combustible material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J36/00—Parts, details or accessories of cooking-vessels
- A47J36/24—Warming devices
- A47J36/30—Devices for warming by making use of burning cartridges or other chemical substances
Abstract
ABSTRACT OF THE DISCLOSURE:
A heating device for heating liquid and solid products comprises a container structure and heating means located at the base of the container structure, the heating means comprising a heating element including a supply of exothermic gas-less combustible material. The heating element consists of a flat tile like three-layer element comprising a first heat spreading layer made of heat conduct-ing material, a second, intermediate layer composed of the exothermic gas less combustible material, and a third layer made of heat insulating incombustible material. Ignition means are in operable contact with the combustible material through an opening in at least one of the said first and second layers encasing the combustible material. The heating element further comprises walls arranged throughout the second layer and dividing the combustible material to define at least one fire path extending from the opening for the ignition means.
A heating device for heating liquid and solid products comprises a container structure and heating means located at the base of the container structure, the heating means comprising a heating element including a supply of exothermic gas-less combustible material. The heating element consists of a flat tile like three-layer element comprising a first heat spreading layer made of heat conduct-ing material, a second, intermediate layer composed of the exothermic gas less combustible material, and a third layer made of heat insulating incombustible material. Ignition means are in operable contact with the combustible material through an opening in at least one of the said first and second layers encasing the combustible material. The heating element further comprises walls arranged throughout the second layer and dividing the combustible material to define at least one fire path extending from the opening for the ignition means.
Description
HeatinF device The present inver tion relates to a heating device for heating liquid anr. ~olid products.
i~ nulnher of diflerent types of devices comprising a container structure and a heating element, i.e. so called self-heating containers, have u.en previously proposed, which inclucle a substance capable o~ giving rise to an ex~thermic reaction, so that when th~ reaction occurs the contents of the container are heated.
lt is known from the literature that the burning time of a heating element clepends not only on the composition which is used, but also ol) the heat conductivity characteristics of its receptacle and how the heat produced by the reaction is extracted frorn the mass. In order to con~rol and to increase the duration of the reaction, it has been proposed to ernbe~, in the exothermic combustible material, internal walls or partitions of some refractory rnaterial reaching from the top to the bottorn of the heating element and insuring a fire path.
.
Some devices of ~his type are dangerous lo operate, since the heating element is not insulated from the surroundings or may be separated from the container and then actuated. As a result the heat flow produ-ced is not absorbed by the container and its contents, but rather is directed towards the surroundings.
As ~he heat produced in such heating devices, particularly those of the thermite type, can have an extremely high temperature value, up to 1 200~C, such devices are dangerous to handle manually and may cause f ires or explosions. In addition, previously proposed arrangements have not satisfactorily heated the contents of the container in a uniform manner, nor have they been convenient or simple to use.
It is an object of the present invention to provide a heating device which comprises a suitable structure allowing a proper heat dissipation to the contents of the container or food preserve and providing uniform heating thereof whilst insuring complete heat insulation to the surroun-dings and therefore great safety in use.
Another object of the present invention is to provide a heating device that includes a relatively simple and safe ignition arrangement for the combustible material which is reliable in use and which requires no special accuracy in manufacturing.
A further object of the present invention is to provide a heatin~ device which is cheap to manufacture for its manufacturing can be automated.
A still further object of the invention is to completely separate the conditioning of the food into a sterile packaging and the manufacturing of the heatin~ element, both being assembled as completed units.
~ 3 -Yet another obj~ct of the present inventi~n is ~o provide an improved exothermic gas-less composition in liquid or semi-liquid form by the use of a liquid binder for it is well known that it is much easier to handle a liquid or a paste rather than powder. The use ot liquids or pastes allow to get cakes of c~m~osition with a fully controlLed porosity and this for any shape which can be casted, while powders can onl.y be compressed to a given porosity or den-sity in very limited shapes such as cylinders. It is well known from the pyroterhnical art that the porosity of a pyrotechnical reactive mass is determinant Eor its burning speed.
According to the present invention -there is there-fore provided a heati:ng device for heating liquid and solid products comprising a container structure and heating means located at the base of the container structure, said heating means comprising a heating element including a supply of exothermic gas-less combustible material characterized in that said heating element consists of a flat tile like three-layer element comprising a first heat spreading layer made of heat conducting material, a second, intermediate layer composed of said exothermic gas-less combustible material and a third la~er made of heat insulating incom-bustible materiaL, ignition means being in operable contact with said combustible material through an opening in at least one of said f.Lrst and second layers encasing the com bustible material and., said heatiny element further com-prLsing walls arranged throughout said second layer and dividing said combust.ible mater:Lal to define at least one fire path extending from said opening for said ignition means.
The above., and other objects, featu.res and advan tacJes o~ this inventi.on will. be apparent in the following detailed descr:Lption and the accompanying drawings, wherein:
Figure l ShoW5 a heating device with a cross-il~
i3 - 3a -section of its bottom part, Figure 2 shows a top view of said container with a cros~-section along line II - II of f ....
Figure 3 shows the heating element separated from the container7 Figure 4 shows another embodiment of the invention, Figure 5 is a perspective view of the starter used in the embodiment of figure 4, Figure 6 shows a cross sec~ion through a heating element7 Figure 7 is a cross section through a third embodiment of the nvention and Figure 8 shows a cross section through the heating element of the embodiment illustrated in figure 7.
The heating device shown in the figures 1, 2 and 3 consists in a con-tainer with a peripheral wall 102 preferably made of metal to which is secured in a water ~ight manner a flat, relatively thick, bottom part 103 made of good heat conclucting material such as aluminium A portion 104 of the peripheral wall 102 extends beyond the bottom plate 103 forrning the recess which can accomodate the heating element 105 and its ignition system 106. A ring shapped element 107 is inserted against the peripheral wall 102. This ring shapped element guides and supports cover 108 which is engaged in a frictional relationship with the ring 107.
This cover is lined with insulating material 109. This material can consist of glass fibers, rockwoolg ceramix etc. This cover maintains pressed against bottom 103 the heating element 105, the recess 1 10 provided in the insulating material accomodates the ignition system.
The heating element shown in figure 3 consists in a heat diffusion plate 111 made of a good heat conducting material such as aluminium.
Perpendicular walls 112 made of heat conducting material, such as steel, are secured to the h~eat diffusion plate 111 in a heat transrnitting way. lhese walls define th,e fire path for the exothermic material 113 contained therein. A con~enient shape for the fire path is a spiral like disposition of these walls. The exothermic material 113 consisting of a therrnitic cornposi ~ion such as manganese dioxide and silicon and an inert materlal such as silica added with a suitable binder such as a silicate is c:asted in the fire path.
Several inventors have proposed in the past to use thermite which is a reaction of iron oxide with aluminium as exothermic material.
The reac~ion tempera~ure which is over 2.00GC led to plunger ~ype constructions which are very unfavourable as far as -the heat transfer to the food to be heated. The idea of the invention is to provide a container in which the food is heated from the bottom such as to provide a natural convection for liquids or to allow stewing. This is possible through the use of reactive composi tions burning at lower temperatures. It was found tha~ silicon with various oxydants like red lead, manganese dioxide, c opper oxide, give a gas-less exothermic reaction, the speed of propa~ation of which can be controlled by the addition of inert material such as silica, china clay etc. It has been found that the use of oxydants containing little oxygen like minium gives lower reaction te[npe~ratures than the ones containing a great amount of oxygen like manganese dioxide and that the heat output per unit of weight could be adjusted by using two or more oxydants, for example a mixture of manganese dioxide and minium as well as by varing the amount o~ inerl~ materialO
The exothermic material is covered by a layer of heat insulating mate-rial such as finely ground silica with a suitable binder such as silica~e or with plaster. Before casting the exothermic material 113 and the insulatin~ layer 11~, a primer 115 is placed at the centre of the spiral.
This primer consists in a c~omposition which is reactive when heated up to approximately ~00C. ,~ typical composition of this type is finely ground silicon mixed with lead oxide (Pb 02). This composition mixed with a suitable binder such as silicate is cast in a separate mould in order to form a cup shaped body with a finger lil<e free standing body, like conical part 116, protr~llding from the bottom. The external walls of this primer are in contact with the exothermic material 113 and this primer is acclessible through an opening in the layer 114 o~ insulating rna~erial.
The i~nition means consisl: in a thin rnetal strip 118. The ends of this metal strip are bent over the end of the rim of the heating element as shown in 117. This U shape elemellt is located by a slight spring action of the legs 1 17~ T he metal str;p I 18 is pierced at its centre;
a drop 120 o~ exothermic material burning with very high hea~ such as a mixture of boron powder and potassium perchlorate ~KCI 04) bound with a glue is casted on the hole in such a way that the pas~like mate-rial protrudes through the hole 119. A fric~ion sensitiYe material 121 equally bcund with glue such as a match head composition is cast on the other side of the me~:al strip. A pull tab 122 consisting of a strip of stron~ paper or similalr material covered on one side wi~h match strikin~ material is laid accross the match head composition 121 ard maintained resiliently against it by a thin fiexible metal strip 123 spots welded at both ends 124 - 125 to the strip 118. As shown in figure 1, this ignition means are placed on the heating element, the exothermic material 1'0 facin~ the openin~ and the cone of the pri-mer 116.
A cavity 110 made in the insulating layer 109 of cover 108 accomodates the protr~lding part of these ignition means 118. Slots 127 and 12~ are provided between the insulating layer o~ the cover and the heating element and between the cover 108 and the body of the container 101.
The pull tab 122 protrudes through the slot 127 to the outside.
The function of the heating device is the following: after having filled the container 101 with the food to be heated, the pull-tab 122 i3 pulled out, ignitin~ by friction the match head composition 121 which communicates the fire to the exothermic composition 120. The heat radiated by this cormposition is strong enough to ignite the cone 116 of the primer, the reaction propagates through the body of the primer by contact to the exothermic material 113 which fills the fire-path. The heat generated by the slowly progressing reaction is conducted by the metal :fins 1 12 to the heated dissipating plate I 11 which is in contact with bottorn plate 103 of the container to which the heat is transferred and wh~ch acts as a further heat spreading element.
Thickness of the bottom 103 is chosen in such a way as to insure a proper heat dissipation in the whole botlom avoiding scorching of the food to be heated. By varying the proportions of the constituents of the exothermic cornposition, the speed of the propagation o~ the reaction can be adjusted and it is preferably maintained such as $o produce not more than 25 Watts per square centimeter when considering the ~otal surface of the heat dissipating plate 111.
A~ter burning out, the heating element 105 can easily be removed and replaced by a new one.
For safety reasons9 the heating element should not be operable when not properly secured in the bottom of container 101. As described here above, the ignition system is located on the heating element by the two resilient legs 11;7 pressing against side walls of the heating element~ When outside the container, if the pull tab is ac~uated, the whole ignition system is pulled away without functioning. In the contai-ner the ignition system is maintained in place by the mating recesses 110 formed in the insulating layer 109 of cover 108.
In the second embodiment of the invention shown in figure 4, the ~eating element consists in a deep drawn dish shaped member 201 made of a good heat conductive material such as aluminium, the L~ottom. 202 of which is the heat dispersing surface. The peripheral wall 203 is obtained by deep drawing process and can be thinned down to save rnaterial. Perpendicùlar walls 204 made of a heat conductive material like steel are secured in a heat conductive contact to the heat disper-sing plate 202 in a configuration as to form a fire path. An ideal configuratioo is a spiral 21S shown in figure 6. A thin insulatin~ layer 205 made of he~t resistant rnaterial such as silica bound with a silicate is cast in the fire path. A cup shaped primer 206 with in its centre ~r~ a protruding cone is placecl at the centre of the spiral on the thin heat insulatirIg layer 205. The exothermic reactive material 207 is mixed to a suitable binder like a silicate and cast in the fire path. The end of the last turn of the spiral 204 is bent in such a way as ~o close the fire path leaving an annular space 209 between wall 203 and the spiral. On top of the exothermic material 207 an insulating layer 210 which can consist of silica bound with a silicate or plaster is cast filling also the annular recess 209. A ring shaped spacer 211 made of insulating material like corrugated aluminium foils or glass fibers mat is placed on insulating layer 210. A ring shaped cardboard 212 is placed on the spacer. Starter 213 is located in the centre of the ring. The starter consists in a U shaped metal disc 21~, spot welded to a flat metal disc 215 by spot weldsi 216 - 217 forming between them a channel in which is placed a pull-tab 21~ made of flexible material like paper coated with match striking composition on its end 219, on the side facing the U shaped disc. 1 he U shaped disc is pierced at its centre, a drop 221 of exothermic material such as boron and K perchlorate bound with glue is cast on the hole 220 made in the centre of the U shaped member. ~ drop of match head composition 222 bound with glue is cast on hole 220 on the inside of the U such as to be in contact with exothermic material 221 through said hole. ~ cardboard disc 223 maintains the starter 213 in its location. The end 224 of pull-tab 218 passes through hole 225 made in the cardboard disc 223 and this end of the pull-tab 224 is folded over this cardboard disc. A frac-turable sealing membrane 226 made of water impervious material like polyethylene is placed on top of the disc 223 to maintain in its place the pull-tab. The protruding ends of the receptacle 201 are rolled over maintaining the spacer 211, cardboard discs 212, 223 and the sea-ling foil 226 tightly presse,d in their location. The heating element as described is a completely sealed unit which can easily be stored and handled such as before bein~ adapted to the wall of a container in such a way as to make iIt a self-heatin~ container. In figure 4 part 227 is a tube shaped mernber rnade of a water impervious material such as alurniniurn and plastic films lined cardboard impregnated with silicate~ Thc heatine element 201 is adapted to this tube by a push _ 9 fit strong enough to be water ti~ht. This tube 227 forms the peripheral wall of the sel~ heating container 231. Before filling, the container membrane 226 is fractured, the pull-tab is folded towards the outside of the container as shown in the dotted line 2329 the container is then filled with the medium to be heated. By pulling out ~he pull-tab 218, its coated end 219 rubs against the match head composition 222 which ignites, actiYating the exothermic composi~ion 221, the hea~ radiated by this reaction is strong enough to heat the tip of cone 233 protruding from the bottom of ~he cup shaped primer ~06 above its ignition temperature starting the burning of the primer, which in its turn induces the reaction of exothermic composi~ion 207.
This reaction progresses at a speed comprised between 4 and 20mm per second and the heat released is dissipated by conduction by the heat conducting fins 204 sipreading this heat into the heat dissipating plate 202 from where the heat flows into the medium to be heated.
Ihe insulatmg layer 205 L)Lt!v~lLs a d~ect contact bet~ween the heat dissi-pating plate 202 with the exothermic material; this heat insulating barrier favours the spreading of the heat by the means of the fins into the heat dissipating pllate 202 avoiding hot spots on this plate and scorching of the food to be heated. The heat insulation 210 as well as spacer 211 and the two cardboard discs 212,223 form a multi-layer insulating barrier preventing the heat to flow in the direc:tion opposite to the heat dissipating plate 202. The f ins 204 act as a heat sink conducting the heat into the dissipating plate and avoiding greatly a heat transfer to the unreacted part of the exothermic material which could lead to non controlled progression of the reaction. Exarnple:
According the embodiment shown in figure 4, we ha~/e found that a 70 grarn quantity of heating mix ture can raise the temperature of 400 cc of water iErom norrnal room temperature, say 20C, to 72C
in two minutes. C`aloric outlput is 300 cal.tg.
- lo -ln the third embodiment illustrated in the figures 7 and 8, -the hea~ing element consists in a refractory support 301 made of mouldable material such as plaster, clay etc. The support is moulded in such a way as to create on one side a fire path 303 constituted by grooves separated by the raised walls 302. These walls are disposed in such a way as to form two zi~zags starting flrom the cen~er as shown in Figure 8. The refractory support 301 shows at its center a hole 305 in which a primer 306 is placed. This primer consists in a reactive composition bound with a suitable binder and cast in a separate mould such as to take a cup like shape with a fing;er like element 307 raising inside the cup frorn its bottom. After solidification this primer is placed in hole 305. The reactive mass mi~:ed with a suitable binder is cast in the fire path 303 and ~ets in contact with primer 306. On top of the reacti-ve mass, a layer 308 consisting in finely ground heat conducting material such as a metal powder or a metalloid powder like ~raphite mixed with a suitable heat resistant binder such as a silicate is cast. To reinforce this layer, a thin sheet of non combustible fibers, like glass fibers, can be embedded. This sheet is not shown on the drawlng.
This heating element is secured to the bottom of a cardboard container 309 by gluing or by any other suitable mean. The starter 311 as shown in Figure 5 and described pre~viously is located in a recess of cardboard layer 310. The pull tab 312 protrudesthrough a slot made in wall 313 of the container 309 and is accessible from the exterior. A food preserve 314 consisting in a shallow dish 315 made of thin deep drawn aluminium foil sealed with a thin mem,brane of aluminium 316 is placed on the heating element 301 in such a~ way as to insure contact with the bottom 317 of the preserve with the heat dispersing layer 308. This preserve is firmly locate~l on the cardboard box 309, for example by wedging, or by gluing its edges 318 to the rim 319 of cardboard box 309 with for example a hot rnelt.
i~ nulnher of diflerent types of devices comprising a container structure and a heating element, i.e. so called self-heating containers, have u.en previously proposed, which inclucle a substance capable o~ giving rise to an ex~thermic reaction, so that when th~ reaction occurs the contents of the container are heated.
lt is known from the literature that the burning time of a heating element clepends not only on the composition which is used, but also ol) the heat conductivity characteristics of its receptacle and how the heat produced by the reaction is extracted frorn the mass. In order to con~rol and to increase the duration of the reaction, it has been proposed to ernbe~, in the exothermic combustible material, internal walls or partitions of some refractory rnaterial reaching from the top to the bottorn of the heating element and insuring a fire path.
.
Some devices of ~his type are dangerous lo operate, since the heating element is not insulated from the surroundings or may be separated from the container and then actuated. As a result the heat flow produ-ced is not absorbed by the container and its contents, but rather is directed towards the surroundings.
As ~he heat produced in such heating devices, particularly those of the thermite type, can have an extremely high temperature value, up to 1 200~C, such devices are dangerous to handle manually and may cause f ires or explosions. In addition, previously proposed arrangements have not satisfactorily heated the contents of the container in a uniform manner, nor have they been convenient or simple to use.
It is an object of the present invention to provide a heating device which comprises a suitable structure allowing a proper heat dissipation to the contents of the container or food preserve and providing uniform heating thereof whilst insuring complete heat insulation to the surroun-dings and therefore great safety in use.
Another object of the present invention is to provide a heating device that includes a relatively simple and safe ignition arrangement for the combustible material which is reliable in use and which requires no special accuracy in manufacturing.
A further object of the present invention is to provide a heatin~ device which is cheap to manufacture for its manufacturing can be automated.
A still further object of the invention is to completely separate the conditioning of the food into a sterile packaging and the manufacturing of the heatin~ element, both being assembled as completed units.
~ 3 -Yet another obj~ct of the present inventi~n is ~o provide an improved exothermic gas-less composition in liquid or semi-liquid form by the use of a liquid binder for it is well known that it is much easier to handle a liquid or a paste rather than powder. The use ot liquids or pastes allow to get cakes of c~m~osition with a fully controlLed porosity and this for any shape which can be casted, while powders can onl.y be compressed to a given porosity or den-sity in very limited shapes such as cylinders. It is well known from the pyroterhnical art that the porosity of a pyrotechnical reactive mass is determinant Eor its burning speed.
According to the present invention -there is there-fore provided a heati:ng device for heating liquid and solid products comprising a container structure and heating means located at the base of the container structure, said heating means comprising a heating element including a supply of exothermic gas-less combustible material characterized in that said heating element consists of a flat tile like three-layer element comprising a first heat spreading layer made of heat conducting material, a second, intermediate layer composed of said exothermic gas-less combustible material and a third la~er made of heat insulating incom-bustible materiaL, ignition means being in operable contact with said combustible material through an opening in at least one of said f.Lrst and second layers encasing the com bustible material and., said heatiny element further com-prLsing walls arranged throughout said second layer and dividing said combust.ible mater:Lal to define at least one fire path extending from said opening for said ignition means.
The above., and other objects, featu.res and advan tacJes o~ this inventi.on will. be apparent in the following detailed descr:Lption and the accompanying drawings, wherein:
Figure l ShoW5 a heating device with a cross-il~
i3 - 3a -section of its bottom part, Figure 2 shows a top view of said container with a cros~-section along line II - II of f ....
Figure 3 shows the heating element separated from the container7 Figure 4 shows another embodiment of the invention, Figure 5 is a perspective view of the starter used in the embodiment of figure 4, Figure 6 shows a cross sec~ion through a heating element7 Figure 7 is a cross section through a third embodiment of the nvention and Figure 8 shows a cross section through the heating element of the embodiment illustrated in figure 7.
The heating device shown in the figures 1, 2 and 3 consists in a con-tainer with a peripheral wall 102 preferably made of metal to which is secured in a water ~ight manner a flat, relatively thick, bottom part 103 made of good heat conclucting material such as aluminium A portion 104 of the peripheral wall 102 extends beyond the bottom plate 103 forrning the recess which can accomodate the heating element 105 and its ignition system 106. A ring shapped element 107 is inserted against the peripheral wall 102. This ring shapped element guides and supports cover 108 which is engaged in a frictional relationship with the ring 107.
This cover is lined with insulating material 109. This material can consist of glass fibers, rockwoolg ceramix etc. This cover maintains pressed against bottom 103 the heating element 105, the recess 1 10 provided in the insulating material accomodates the ignition system.
The heating element shown in figure 3 consists in a heat diffusion plate 111 made of a good heat conducting material such as aluminium.
Perpendicular walls 112 made of heat conducting material, such as steel, are secured to the h~eat diffusion plate 111 in a heat transrnitting way. lhese walls define th,e fire path for the exothermic material 113 contained therein. A con~enient shape for the fire path is a spiral like disposition of these walls. The exothermic material 113 consisting of a therrnitic cornposi ~ion such as manganese dioxide and silicon and an inert materlal such as silica added with a suitable binder such as a silicate is c:asted in the fire path.
Several inventors have proposed in the past to use thermite which is a reaction of iron oxide with aluminium as exothermic material.
The reac~ion tempera~ure which is over 2.00GC led to plunger ~ype constructions which are very unfavourable as far as -the heat transfer to the food to be heated. The idea of the invention is to provide a container in which the food is heated from the bottom such as to provide a natural convection for liquids or to allow stewing. This is possible through the use of reactive composi tions burning at lower temperatures. It was found tha~ silicon with various oxydants like red lead, manganese dioxide, c opper oxide, give a gas-less exothermic reaction, the speed of propa~ation of which can be controlled by the addition of inert material such as silica, china clay etc. It has been found that the use of oxydants containing little oxygen like minium gives lower reaction te[npe~ratures than the ones containing a great amount of oxygen like manganese dioxide and that the heat output per unit of weight could be adjusted by using two or more oxydants, for example a mixture of manganese dioxide and minium as well as by varing the amount o~ inerl~ materialO
The exothermic material is covered by a layer of heat insulating mate-rial such as finely ground silica with a suitable binder such as silica~e or with plaster. Before casting the exothermic material 113 and the insulatin~ layer 11~, a primer 115 is placed at the centre of the spiral.
This primer consists in a c~omposition which is reactive when heated up to approximately ~00C. ,~ typical composition of this type is finely ground silicon mixed with lead oxide (Pb 02). This composition mixed with a suitable binder such as silicate is cast in a separate mould in order to form a cup shaped body with a finger lil<e free standing body, like conical part 116, protr~llding from the bottom. The external walls of this primer are in contact with the exothermic material 113 and this primer is acclessible through an opening in the layer 114 o~ insulating rna~erial.
The i~nition means consisl: in a thin rnetal strip 118. The ends of this metal strip are bent over the end of the rim of the heating element as shown in 117. This U shape elemellt is located by a slight spring action of the legs 1 17~ T he metal str;p I 18 is pierced at its centre;
a drop 120 o~ exothermic material burning with very high hea~ such as a mixture of boron powder and potassium perchlorate ~KCI 04) bound with a glue is casted on the hole in such a way that the pas~like mate-rial protrudes through the hole 119. A fric~ion sensitiYe material 121 equally bcund with glue such as a match head composition is cast on the other side of the me~:al strip. A pull tab 122 consisting of a strip of stron~ paper or similalr material covered on one side wi~h match strikin~ material is laid accross the match head composition 121 ard maintained resiliently against it by a thin fiexible metal strip 123 spots welded at both ends 124 - 125 to the strip 118. As shown in figure 1, this ignition means are placed on the heating element, the exothermic material 1'0 facin~ the openin~ and the cone of the pri-mer 116.
A cavity 110 made in the insulating layer 109 of cover 108 accomodates the protr~lding part of these ignition means 118. Slots 127 and 12~ are provided between the insulating layer o~ the cover and the heating element and between the cover 108 and the body of the container 101.
The pull tab 122 protrudes through the slot 127 to the outside.
The function of the heating device is the following: after having filled the container 101 with the food to be heated, the pull-tab 122 i3 pulled out, ignitin~ by friction the match head composition 121 which communicates the fire to the exothermic composition 120. The heat radiated by this cormposition is strong enough to ignite the cone 116 of the primer, the reaction propagates through the body of the primer by contact to the exothermic material 113 which fills the fire-path. The heat generated by the slowly progressing reaction is conducted by the metal :fins 1 12 to the heated dissipating plate I 11 which is in contact with bottorn plate 103 of the container to which the heat is transferred and wh~ch acts as a further heat spreading element.
Thickness of the bottom 103 is chosen in such a way as to insure a proper heat dissipation in the whole botlom avoiding scorching of the food to be heated. By varying the proportions of the constituents of the exothermic cornposition, the speed of the propagation o~ the reaction can be adjusted and it is preferably maintained such as $o produce not more than 25 Watts per square centimeter when considering the ~otal surface of the heat dissipating plate 111.
A~ter burning out, the heating element 105 can easily be removed and replaced by a new one.
For safety reasons9 the heating element should not be operable when not properly secured in the bottom of container 101. As described here above, the ignition system is located on the heating element by the two resilient legs 11;7 pressing against side walls of the heating element~ When outside the container, if the pull tab is ac~uated, the whole ignition system is pulled away without functioning. In the contai-ner the ignition system is maintained in place by the mating recesses 110 formed in the insulating layer 109 of cover 108.
In the second embodiment of the invention shown in figure 4, the ~eating element consists in a deep drawn dish shaped member 201 made of a good heat conductive material such as aluminium, the L~ottom. 202 of which is the heat dispersing surface. The peripheral wall 203 is obtained by deep drawing process and can be thinned down to save rnaterial. Perpendicùlar walls 204 made of a heat conductive material like steel are secured in a heat conductive contact to the heat disper-sing plate 202 in a configuration as to form a fire path. An ideal configuratioo is a spiral 21S shown in figure 6. A thin insulatin~ layer 205 made of he~t resistant rnaterial such as silica bound with a silicate is cast in the fire path. A cup shaped primer 206 with in its centre ~r~ a protruding cone is placecl at the centre of the spiral on the thin heat insulatirIg layer 205. The exothermic reactive material 207 is mixed to a suitable binder like a silicate and cast in the fire path. The end of the last turn of the spiral 204 is bent in such a way as ~o close the fire path leaving an annular space 209 between wall 203 and the spiral. On top of the exothermic material 207 an insulating layer 210 which can consist of silica bound with a silicate or plaster is cast filling also the annular recess 209. A ring shaped spacer 211 made of insulating material like corrugated aluminium foils or glass fibers mat is placed on insulating layer 210. A ring shaped cardboard 212 is placed on the spacer. Starter 213 is located in the centre of the ring. The starter consists in a U shaped metal disc 21~, spot welded to a flat metal disc 215 by spot weldsi 216 - 217 forming between them a channel in which is placed a pull-tab 21~ made of flexible material like paper coated with match striking composition on its end 219, on the side facing the U shaped disc. 1 he U shaped disc is pierced at its centre, a drop 221 of exothermic material such as boron and K perchlorate bound with glue is cast on the hole 220 made in the centre of the U shaped member. ~ drop of match head composition 222 bound with glue is cast on hole 220 on the inside of the U such as to be in contact with exothermic material 221 through said hole. ~ cardboard disc 223 maintains the starter 213 in its location. The end 224 of pull-tab 218 passes through hole 225 made in the cardboard disc 223 and this end of the pull-tab 224 is folded over this cardboard disc. A frac-turable sealing membrane 226 made of water impervious material like polyethylene is placed on top of the disc 223 to maintain in its place the pull-tab. The protruding ends of the receptacle 201 are rolled over maintaining the spacer 211, cardboard discs 212, 223 and the sea-ling foil 226 tightly presse,d in their location. The heating element as described is a completely sealed unit which can easily be stored and handled such as before bein~ adapted to the wall of a container in such a way as to make iIt a self-heatin~ container. In figure 4 part 227 is a tube shaped mernber rnade of a water impervious material such as alurniniurn and plastic films lined cardboard impregnated with silicate~ Thc heatine element 201 is adapted to this tube by a push _ 9 fit strong enough to be water ti~ht. This tube 227 forms the peripheral wall of the sel~ heating container 231. Before filling, the container membrane 226 is fractured, the pull-tab is folded towards the outside of the container as shown in the dotted line 2329 the container is then filled with the medium to be heated. By pulling out ~he pull-tab 218, its coated end 219 rubs against the match head composition 222 which ignites, actiYating the exothermic composi~ion 221, the hea~ radiated by this reaction is strong enough to heat the tip of cone 233 protruding from the bottom of ~he cup shaped primer ~06 above its ignition temperature starting the burning of the primer, which in its turn induces the reaction of exothermic composi~ion 207.
This reaction progresses at a speed comprised between 4 and 20mm per second and the heat released is dissipated by conduction by the heat conducting fins 204 sipreading this heat into the heat dissipating plate 202 from where the heat flows into the medium to be heated.
Ihe insulatmg layer 205 L)Lt!v~lLs a d~ect contact bet~ween the heat dissi-pating plate 202 with the exothermic material; this heat insulating barrier favours the spreading of the heat by the means of the fins into the heat dissipating pllate 202 avoiding hot spots on this plate and scorching of the food to be heated. The heat insulation 210 as well as spacer 211 and the two cardboard discs 212,223 form a multi-layer insulating barrier preventing the heat to flow in the direc:tion opposite to the heat dissipating plate 202. The f ins 204 act as a heat sink conducting the heat into the dissipating plate and avoiding greatly a heat transfer to the unreacted part of the exothermic material which could lead to non controlled progression of the reaction. Exarnple:
According the embodiment shown in figure 4, we ha~/e found that a 70 grarn quantity of heating mix ture can raise the temperature of 400 cc of water iErom norrnal room temperature, say 20C, to 72C
in two minutes. C`aloric outlput is 300 cal.tg.
- lo -ln the third embodiment illustrated in the figures 7 and 8, -the hea~ing element consists in a refractory support 301 made of mouldable material such as plaster, clay etc. The support is moulded in such a way as to create on one side a fire path 303 constituted by grooves separated by the raised walls 302. These walls are disposed in such a way as to form two zi~zags starting flrom the cen~er as shown in Figure 8. The refractory support 301 shows at its center a hole 305 in which a primer 306 is placed. This primer consists in a reactive composition bound with a suitable binder and cast in a separate mould such as to take a cup like shape with a fing;er like element 307 raising inside the cup frorn its bottom. After solidification this primer is placed in hole 305. The reactive mass mi~:ed with a suitable binder is cast in the fire path 303 and ~ets in contact with primer 306. On top of the reacti-ve mass, a layer 308 consisting in finely ground heat conducting material such as a metal powder or a metalloid powder like ~raphite mixed with a suitable heat resistant binder such as a silicate is cast. To reinforce this layer, a thin sheet of non combustible fibers, like glass fibers, can be embedded. This sheet is not shown on the drawlng.
This heating element is secured to the bottom of a cardboard container 309 by gluing or by any other suitable mean. The starter 311 as shown in Figure 5 and described pre~viously is located in a recess of cardboard layer 310. The pull tab 312 protrudesthrough a slot made in wall 313 of the container 309 and is accessible from the exterior. A food preserve 314 consisting in a shallow dish 315 made of thin deep drawn aluminium foil sealed with a thin mem,brane of aluminium 316 is placed on the heating element 301 in such a~ way as to insure contact with the bottom 317 of the preserve with the heat dispersing layer 308. This preserve is firmly locate~l on the cardboard box 309, for example by wedging, or by gluing its edges 318 to the rim 319 of cardboard box 309 with for example a hot rnelt.
2~
This whoie assembly constitutes a self heating food preserve. Af ter removing cover 316~ the heating reaction is star~ed by pulling out pull tab 312.
It is obvious that this heating device could be suppiied witn the container 315 being empty, this apparatus constituting a disposable self heating container.
The primer 306 could be placed in reverse position directly in the fire path, accessible through an opening in the heat dispersing layer 303. In this case, the starter should be placed between bottom 317 of the container 315 and heat dispersing layer 308. The f in8er like body 307 could also be tipped with a friction sensitive material and the pull tab rnaintained resiliently against friction sensitive tip.
Similarly the primer 306 could be placed in a hole of one of the side walls 320 of tlle heating element, the starter being located adequately between wall 320 and the vertical wall of cardboard 309.
This whoie assembly constitutes a self heating food preserve. Af ter removing cover 316~ the heating reaction is star~ed by pulling out pull tab 312.
It is obvious that this heating device could be suppiied witn the container 315 being empty, this apparatus constituting a disposable self heating container.
The primer 306 could be placed in reverse position directly in the fire path, accessible through an opening in the heat dispersing layer 303. In this case, the starter should be placed between bottom 317 of the container 315 and heat dispersing layer 308. The f in8er like body 307 could also be tipped with a friction sensitive material and the pull tab rnaintained resiliently against friction sensitive tip.
Similarly the primer 306 could be placed in a hole of one of the side walls 320 of tlle heating element, the starter being located adequately between wall 320 and the vertical wall of cardboard 309.
Claims (20)
1. A heating device for heating liquid and solid products comprising a container structure and heating means located at the base of the container structure, said heating means comprising a heating element including a supply of exothermic gas-less combustible material characterized in that said heating element consists of a flat tile like three-layer element comprising a first heat spreading layer made of heat conducting material, a second, intermediate layer composed of said exothermic gas-less combustible material, and a third layer made of heat insulating incom-bustible material, ignition means being in operable contact with said combustible material through an opening in at least one of said first and second layers encasing the com-bustible material and, said heating element further compris-ing walls arranged throughout said second layer and dividing said combustible material to define at least one fire path extending from said opening for said ignition means.
2. A heating device according to claim 1, charac-terized in that said ignition means comprises an ignition element including a finger like free standing member in con-tact with said combustible material, a free end of said member being adapted for ignition.
3. A heating device according to claim 1, charac-terized in that the ignition means comprises an element made of friction sensitive material and a striker arranged to be drawn accross said friction sensitive element.
4. A heating device according to claim 3, charac-terized in that said friction sensitive element is adapted to ignite said free end of the finger by contact less heat radiation.
5. A heating device according to claim 2, charac-terized in that said ignition means further comprises a cup shaped member arranged to have said member protruding sub-stantially from the middle of the cup.
6. A heating device as defined in claim 1, char-acterized in that said walls defining a fire path are of good heat conducting material and in heat transmitting contact with the heat spreading layer.
7. A heating device as defined in claim 1, char-acterized in that said heat spreading layer consists of an aluminium foil.
8. A heating device as defined in claim 1, char-acterized in that said heat spreading layer consists of a finely ground metal or metalloid bound with a heat resistant binder.
9. A heating device as defined in claim 8, char-acterized in that said metalloid is carbon.
10. A heating device as defined in claim 8, char-acterized in that said heat spreading layer includes non combustible fibers.
11. A heating device as defined in claim 1, char-acterized in that said heating element includes a fourth layer comprising a thin heat insulating layer made of heat resistant material interposed between said first heat spread-ing layer and said second layer formed of said exothermic gas-less combustible material.
12. A heating device as defined in claim 1, characterized in that said walls defining a fire path are composed of heat insulating incombustible material made up with said insulating layer in one plate formed by casting.
13. A heating device as defined in claim 1, characterized in that said walls are formed having a pre-determined length to form said fire path, thereby dividing said combustible material to have a surface for combustion such that the heat produced by the exothermic reaction is less than 25 watts per square centimeter of said base.
14. A heating device according to claim 1, characterized in that the tile like element is in contact with the outer face of the bottom of a container.
15. A heating device as defined in claim 1, characterized in that said exothermic gas-less combustible material comprises at least 20 % silicon and at least 10 minium.
16. A heating device as defined in claim 15, characterized in that said exothermic gas-less combustible material contains at least one metal oxide other than minium and a suitable binder.
17. A heating device as defined in claim 16, characterized in that said exothermic gas-less combustible material comprises at least 20 % manganese dioxide.
18. A heating device as defined in claim 15, characterized in that said exothermic gas-less combustible material contains an inert material.
19. A heating device according to claim 1, characterized in that the ingredients of the exothermic gas-less combustible layer are bound together with an uncombustible binder.
20. A heating device according to claim 1 or 19, characterized in that the exothermic gas-less combustible layer and the insulating layer are made from mixtures which can be cast.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE0/209364A BE894859A (en) | 1982-10-28 | 1982-10-28 | Heater for liquids and solids - has container with base heater formed of mass of exothermic material requiring no gas |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1192803A true CA1192803A (en) | 1985-09-03 |
Family
ID=3843569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000415750A Expired CA1192803A (en) | 1982-10-28 | 1982-11-17 | Heating device |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU561141B2 (en) |
| CA (1) | CA1192803A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4949702A (en) * | 1988-08-12 | 1990-08-21 | Nissin Shokuhin Kabushiki Kaisha | Self-heating container |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR960005779B1 (en) * | 1988-03-18 | 1996-05-01 | 신닛뽕 세이데쓰 가부시끼가이샤 | Heat-generating member |
-
1982
- 1982-11-03 AU AU90137/82A patent/AU561141B2/en not_active Ceased
- 1982-11-17 CA CA000415750A patent/CA1192803A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4949702A (en) * | 1988-08-12 | 1990-08-21 | Nissin Shokuhin Kabushiki Kaisha | Self-heating container |
Also Published As
| Publication number | Publication date |
|---|---|
| AU561141B2 (en) | 1987-04-30 |
| AU9013782A (en) | 1984-05-10 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |