Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/40—Heating elements having the shape of rods or tubes
  • H05B3/54—Heating elements having the shape of rods or tubes flexible
  • H05B3/58—Heating hoses; Heating collars
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/013—Heaters using resistive films or coatings
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/017—Manufacturing methods or apparatus for heaters
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/02—Heaters using heating elements having a positive temperature coefficient
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/021—Heaters specially adapted for heating liquids
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
  • H05B2203/022—Heaters specially adapted for heating gaseous material

Definitions

• the invention relates to the field of heaters for fluids contained in tubes with small diameters.
• heating devices are used for fluids contained or flowing in tubes with small or very small flow rates, such as for heating liquids for washing the windows of motor vehicles or also for applications in scientific and electromedical equipment, for example.
• Some important features, which are needed in small heating devices, include heating speed, effectiveness, and efficiency. Furthermore, aspects relating to the safety of the device need to be addressed, such as the capacity to prevent undesired overheating, for example. It is also important for the heating devices to have small dimensions, in particular they need to be very thin in a radial direction, and manufacturable at a low cost, when applied to widely consumed products, and they also need to be light-weight and manageable.
• a further important feature, which is desired in such heating devices is the creation and maintaining of a homogenous temperature in specific zones of a tube where a fluid flows.
• a heating device for heating fluids which, according to claim 1 , comprises a tube having a predetermined length and a longitudinal axis X, covered by a plurality of layers of materials which wrap the tube, where the plurality of layers comprises, considering a cross-section view on a plane transversal to said axis X, a first electrically insulating layer wrapped on the tube; an electrical resistance made from a metal sheet etched so as to form three or more electrical conducting tracks, connected together at two respective ends at two respective terminals, the electrical resistance being wrapped around the first electrically insulating layer; a second electrically insulating layer wrapped around the electrical resistance; a layer of heat-shrinkable material wrapped around the second electrically insulating layer, said layers being arranged in sequence and in the listed order from an outer surface of the
• the aforesaid objective is achieved by a method of manufacturing the heating device having the features in claim 10.
• the invention there is the advantage of having a highly compact heating device, particularly adapted to produce heat with a very low electricity consumption, which can be mounted about tubes having a small diameter in which a fluid flows, with a small flow rate and capable of reaching the working temperature very quickly.
• the device of the invention is particularly advantageous for heating medical, sanitary, edible fluids or industrial fluids, in particular for heating medical, sanitary, edible, and industrial liquids.
• composition of the elements thereof where the heating device operates with an electrical resistance with a PTC effect.
• the small thicknesses of the layers composing the device contribute to a small mass, which ensures very quick response times with low thermal inertia.
• the small volume in a diametral direction optimizes the introduction of the device into existing systems or apparatuses, or however an easy adaptation thereof to such systems or apparatuses.
• the flexibility of the layers also allows the application thereof to tubular shapes with a non-circular section, e.g., elliptical or composite.
• the plurality of tracks of the electrical resistance allows homogenizing the heat distribution over the whole heating device.
• Fig. 1 shows an overall axonometric view of a heating device according to the invention
• Fig. 2 shows a section along an axial plane of the heating device in Fig. 1 ;
• Fig. 2a shows an enlarged detail of the structural element in Fig. 2;
• Fig. 3 shows the view of an electrical heating resistance deployed on a plane and belonging to the heating device in Fig. 1 ;
• Fig. 4 shows an axonometric view of the partially mounted heating device in Fig. 1 ;
• Fig. 5 shows an axonometric view of the heating device in fig. 1 , on which further components are mounted;
• Fig. 6 shows a structural element used in the production cycle of the heating device
• Fig. 6a shows an enlarged detail of the structural element in Fig. 6;
• Fig. 7 shows a partial subset of the device of the invention in an intermediate step of the manufacturing process
• Fig. 8 shows a partial subset of the device of the invention in an intermediate step of the manufacturing process following that in Fig. 7.
• the heating device, or simply heater, of the invention indicated by reference numeral 1 as a whole, comprises a tube 2 defining a longitudinal central axis X, in particular a longitudinal central axis of symmetry X and having a preferably circular section on a plane transversal to the axis X.
• the tube can also have a different cross-section shape from the circular one, e.g., elliptical or polygonal or any other section commonly used in tubes.
• the tube 2 is made of metal, preferably of stainless steel or a plastic or ceramic material, with a thin wall thickness.
• the thickness of the wall of the tube 2 is preferably between 70 and 110 pm (micrometers), preferably of about 90 pm.
• the material can have different wall thicknesses, as a function of the design and use requirements.
• the length of the tube 2 can be selected based on the use thereof and on the amount of heat to be supplied to the fluid.
• the tube 2 can have a limited axial length and be wrapped around another tube (not shown) of greater length where the fluid flows or connected to the other tube in a known manner. In this case, the choice of the material of tube 2 depends on the heat transmission capacity existing with the material of the longer tube where the fluid flows.
• a first adhesive layer 3 (preferably made of silicone or an acrylic material) is wrapped around the outer surface of the tube 2, being for example in the form of a film having a thickness of about 50 pm and preferably square or rectangular in plan when deployed on a plane, or more generally polygonal, as well as the other layers composing the heating device 1.
• a first electrically insulating layer 4, or first insulating layer is wrapped directly around the adhesive layer 3, preferably comprising or consisting of polyimide, e.g., “Kapton®” or a material comprising or consisting of poly-oxy diphenylene-pyromellitimide), and preferably having a thickness of about 25 pm.
• Other materials for this insulating layer can be selected from polyimides, polyesters, silicones, polyamides, fluoropolymers, polyetherimides and polyesterimides.
• a heating layer consisting of an electrical heating resistance 5 (or electrical resistor), in the shape of a flexible metal sheet and with a thickness preferably of about 50 pm, is directly wrapped around the insulating layer 4.
• the electrical resistance 5 is adapted to generate heat when it is electrically powered.
• the electrical resistance 5 is made of a material having a PTC (Positive Temperature Coefficient) feature or is coupled to a layer with PTC effect, which allows controlling the passage of electricity in the electrical resistance 5 and thus interrupting the heating when the predetermined design temperature is reached.
• a small tube 8 made of a plastic material is directly wrapped around the second insulating layer 7, which has the property of shrinking when heated, e.g., the material commercially known as thermoshrink PEEK.
• the heating device 1 after undergoing the final heating which causes the tube 8 to shrink, takes a compact shape which contributes to keeping all the layers 3, 4, 5, 6, 7, 8 tightened together, in particular sealed, around the tube 2, giving the heating device 1 its final shape. It is possible to use a final fixing system for the layers, which is different from the small heat shrinkable tube 8.
• a temperature sensor 9, with a related electrical circuit 16 is conveniently fixed to the second insulating layer 7 before the small tube 8, wrapped around the tube, is shrunk by heating and when the small tube is shrunk, it also tightens the sensor 9 firmly along with the layers. Thereby, the temperature of the heater can be measured with precision during operation.
• the temperature sensor 9 is positioned so that after completing the winding of the layers, the sensor is positioned in a hole made on the underlying insulating layers. Thereby, at the end of the assembly operations, the sensor 9 is fixed in direct contact with the tube 2, and a particularly precise measurement of the tube 2 wall is obtained.
• a cable 10 can be provided for transmitting the data on the working temperature of the heating device 1 during use, detected by the sensor 9, which is brought out of one end of the small tube 8 and which can thus be connected to a possible electrical or electronic circuit to control the use of the heating device 1 .
• the current supply needed for the electrical resistance 5 is obtained by means of the two cables 1 1 and 12 which are fixed, in a known manner, e.g., by brazing, to the terminals 13, 14 of the electrical resistance 5 and they cause the current to arrive from batteries or accumulators specifically provided, but the electrical supply can be achieved using other known means.
• the electrical resistance 5 is made by etching the tracks 15’, 15”, 15”’ from a flexible sheet of current-conducting metal, such as copper, for example.
• the tracks 15’, 15”, 15’” are three in number, joined parallel to one another to the ends forming the terminals 13, 14.
• the electrical cables 1 1 and 12 are connected, at the other respective end thereof, to the electrical source, not shown, and to the possible electronic control circuit in a manner well known to those skilled in the art, based on the applications for which the heating device is designed.
• the method includes coupling the metal sheet, in the shape of leaf, e.g., of copper, to an insulating material sheet 4, preferably by hot pressing. Then, with the two layers coupled, the metal part is etched to obtain the electrical resistances 5 seen in Fig. 6, one of which is enlarged in Fig. 6a.
• Photoengraving process of the known type can be used, such as application of photosensitive layer, photo impression, etching by means of acids and removal of a photosensitive layer, for example.
• the sheet 17, or substrate, on which several etched electrical resistances 5 arranged, for example, according to a matrix are obtained is cut into pieces 20, preferably having a substantially quadrangular shape, e.g., substantially rectangular, with the desired dimensions for wrapping them around the tubes 2 to obtain the heating devices 1 .
• each piece 20 are such that the longer side of the rectangle is selected to be substantially double the length of the circumference of the tube 2.
• the electrical resistance 5 is arranged on one part of the piece 20, corresponding to about half of the surface thereof, while the part on which there is the circuit or connection 16 corresponds to the other half of the surface of the piece 20.
• a layer 3 of adhesive material is laid over the outer surface of the tube 2.
• the piece 20 is then wrapped around the tube 2, with the face on which the electrical resistance 5 is fixed facing outside, and by virtue of the length thereof, two windings are made around the tube 2.
• the step of etching the electrical resistances 5 can be carried out from the single thin sheet of electrical conductor material or metal sheet, without previously gluing it onto a layer of insulating material.
• all the electrical resistances 5 and connections 16, after etching, are transferred and glued onto a thin sheet 4 of insulating material.
• the next step consists in cutting the insulating material sheet 4 into pieces 20, or strips, preferably having a substantially quadrangular shape, in plan, preferably rectangular or square, as shown in Fig. 6a.
• the piece 20 is then wrapped around the tube 2 arranging the face on which the electrical resistance 5 is fixed outwards, and also in this case two windings are made around the tube 2, as explained above.
• other circuits can also be obtained from the metal sheet, intended to be arranged on each of the pieces 20, e.g., for connecting other types of sensor.
• all the pieces 20 are made with the same dimensions, which are sufficient to allow two complete windings around the tube 2, so that the electrical resistance 5 and the temperature sensor 9, at the end of the winding, are arranged in the position which causes the temperature sensor 9 to take the position on the surface of the electrical resistance 5 where the maximum temperature is generated during operation.
• the temperature sensor 9 is fixed to the circuit 16 by welding or brazing, and the two terminals 13, 14 of the electrical resistance 5 are welded to the electrical conductors 1 1 and 12, preferably and advantageously by laser welding.
• a small tube 8 made of a heat shrinkable material is wrapped, which, after being heated above a certain temperature, tightens all the underlying layers, e.g., it is a material comprising or consisting of PEEK (polyether ether ketone), such as thermoshrink PEEK, or a similar product serving the same purposes.
• PEEK polyether ether ketone
• the first adhesive material layer 3 is applied to the face of the electrically insulating layer 4 opposite to that on which the electrical resistance 5 and the temperature sensor 9 are fixed and only at the surface half where the electrical resistance 5 is positioned.
• an aggregation is prepared (i.e., a preassembled component is formed), including the adhesive layer 3, with the electrically insulating layer 4 and the electrical resistance 5 on top, and then the adhesive layer 3 is arranged first in contact with the outer surface of the tube 2, and the aggregation consisting of the three elements is rolled up: also in this case, two windings are made around the tube 2 because of the dimension of the larger side of the piece 20.
• the adhesion of the electrically insulating layer 4 to the surface of the tube 2 is increased.
• a second adhesive layer is wrapped around the electrical resistance 5 after this is wrapped around the tube 2 according to the methods explained above.
• This variant can be obtained by extending the adhesive layer 3 over the whole surface of the electrically insulating layer 4 opposite to the surface where the heating resistance 5 and the circuit 16 are glued.
• the first 3 and second 6 adhesive layers may also not be used together, in a variant of the invention, or only one of the two or none of the two can be used. If both adhesive layers 3 and 6 are obtained together, this can be done by gluing only one adhesive layer or adhesive sheet which covers the whole surface of the piece 20 on the side opposite to the side where the electrical resistance 5 and the circuit 16 are glued, or this can be done by gluing two different pieces 3 and 6 onto the same side.
• the length of the piece 20 is preferably defined as double the length of the circumference of the outer surface of the tube 2, at the end of the process of winding the layers 3, 4, 5 about the tube 2, the final structure of the heating device 1 , seen in a crosssection to the axis of the tube 2, and from the outer surface of the tube 2, contains the first adhesive layer 3, the electrically insulating layer 4, the electrical resistance 5, the second adhesive layer 6 (which, in a variant shown above, is a part of the same adhesive layer 3), the second electrically insulating layer 7 (which, in a variant already shown above, is a part of the same electrically insulating layer 4), and the heat shrinkable material layer 8.
• Fig. 2a shows the distribution of the layers in this particular preferred variant of the invention.
• the cross-section structure of the heating device 1 would be correspondingly different, as those skilled in the art can easily understand.

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Applications Claiming Priority (2)

Publications (1)

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ID=75111659

Family Applications (1)

Country Status (3)

Family Cites Families (5)

• 2020
  • 2020-12-18 IT IT102020000031331A patent/IT202000031331A1/it unknown
• 2021
  • 2021-12-17 WO PCT/IB2021/061927 patent/WO2022130319A1/en unknown
  • 2021-12-17 EP EP21844051.9A patent/EP4265058A1/de active Pending

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