WO2008150172A1 - Élément de chauffage et récipient pour liquide fourni avec un tel élément de chauffage - Google Patents

Élément de chauffage et récipient pour liquide fourni avec un tel élément de chauffage Download PDF

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Publication number
WO2008150172A1
WO2008150172A1 PCT/NL2008/050360 NL2008050360W WO2008150172A1 WO 2008150172 A1 WO2008150172 A1 WO 2008150172A1 NL 2008050360 W NL2008050360 W NL 2008050360W WO 2008150172 A1 WO2008150172 A1 WO 2008150172A1
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WO
WIPO (PCT)
Prior art keywords
heating element
heating
dielectric layer
track
layer
Prior art date
Application number
PCT/NL2008/050360
Other languages
English (en)
Inventor
Simon Kaastra
Original Assignee
Otter Controls Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Otter Controls Limited filed Critical Otter Controls Limited
Priority to CN200880101804.3A priority Critical patent/CN101772985B/zh
Priority to EP08766783.8A priority patent/EP2163130B1/fr
Publication of WO2008150172A1 publication Critical patent/WO2008150172A1/fr

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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
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
    • H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
    • 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
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
    • H05B3/26—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base
    • 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
    • H05B2203/002—Heaters using a particular layout for the resistive material or resistive elements
    • H05B2203/003—Heaters using a particular layout for the resistive material or resistive elements using serpentine layout
    • 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
    • H05B2203/021—Heaters specially adapted for heating liquids

Definitions

  • Heating element and liquid container provided with such a heating element
  • the invention relates to a heating element.
  • the invention also relates to a liquid container provided with such a heating element.
  • the use of enamel as dielectric intermediate layer in the manufacture of heating elements is known.
  • the dielectric enamel layer is herein arranged on a generally metal substrate for heating, after which metal heating tracks are arranged on the dielectric enamel layer by means of silkscreen techniques.
  • Such a heating element is for instance described in Netherlands patent application NL 1014601. Described herein is a heating element, for instance for heating liquid in liquid containers or for heating of heating plates, wherein heat is generated by conducting electric current through the at least one heating track.
  • the heating track is herein arranged via a dielectric layer on a substrate for heating.
  • the intermediate layer with dielectric properties not only provides for a good transmission of the generated heat to the substrate for heating, but also for an electric barrier between the - usually metal - substrate for heating and the heating track, whereby short-circuiting in the heating element can be prevented under normal operating conditions.
  • the dielectric can moreover function as protection against overheating.
  • the heating element according to NL 1014601 is provided for this purpose with an ammeter which can detect the leakage current through the dielectric.
  • the leakage current coming from the heating element depends partly on the electrical resistance of the dielectric. Because the electrical resistance of the dielectric, at least in a determined temperature range, in turn depends on the temperature, and this dependence can in principle be predetermined, the detection of the leakage current through the dielectric provides insight into the temperature thereof.
  • the leakage current which can be detected in simple manner with an ammeter therefore forms a measurement value with which the temperature of the dielectric, and thus of the heating element, can be determined.
  • a protection against overheating can be easily built in by coupling the ammeter to a control for the heating element, whereby the supply of current to the heating element can be reduced or even wholly interrupted when a pre-defined minimal leakage current is detected.
  • the known heating element provides a simple detection of temperature changes and protection against overheating, separate provisions must generally be made to enable proper detection of the leakage current. It is thus usually necessary on occasions to for instance amplify or, conversely, attenuate the current strength of the leakage current. It has also been found that the leakage current is generally difficult to detect if the heating element is provided with earthing. In that case a galvanically separated transformer system will have to be incorporated in the earth wire, which is time-consuming.
  • the international patent application WO2006083162 in the name of applicant provides an improved heating element for detecting a temperature change in the heating element with a view to protection against overheating.
  • the improved known heating element comprises a substrate on which are successively arranged a first dielectric layer, an electrically conductive sensor layer, a second dielectric layer and a heating track.
  • the second dielectric layer will generally have a thickness here of about 100 ⁇ m. Owing to the particular assembly of the dielectric a leakage current flowing in the second dielectric layer will preferably be diverted to the sensor layer, since in such a case the first dielectric layer acts as electrically more insulating layer (relative to the second dielectric layer).
  • the improved known heating element also has a number of drawbacks.
  • a significant drawback of the known heating element is that the production process is relatively labour-intensive and time-consuming.
  • gas bubbles possibly formed in the second dielectric layer may result relatively quickly in an accelerated breakdown (electric short-circuiting) between the heating track and the sensor layer, which detracts from the ability to accurately and reliably detect a leakage current flowing through the second dielectric.
  • the invention has for its object, while retaining the advantage of the prior art, to provide an improved heating element with which at least one of the above stated drawbacks can be obviated.
  • the invention provides for this purpose a heating element, comprising: a substrate for heating, at least one first dielectric layer arranged on the conductive substrate, at least one electrically conductive heating track arranged on the first dielectric layer, at least one electrically conductive sensor track arranged on the first dielectric layer at a distance from the heating track, and at least one second dielectric layer arranged on the first dielectric layer, which second dielectric layer connects to at least a part of the heating track and to at least a part of the sensor track.
  • the heating track and the sensor track can be arranged on the first dielectric layer in a single pressing run, which considerably simplifies the production process for manufacturing the heating element according to the invention.
  • the distance between the heating track and the sensor track can moreover be kept relatively large (generally about 500 ⁇ m) in simple manner, whereby the chance of accelerated breakdown between the heating track and the sensor track as a result of gas bubbles possibly situated between the two tracks can be reduced significantly.
  • An additional advantage is that in this way the heating track is substantially fully protected by the dielectric layers, which enhances the lifespan of the heating element according to the invention.
  • leakage currents can thus be measured in relatively efficient manner and at very low current strengths and/or voltages, whereby the (exceeding of a critical) temperature of the heating element according to the invention can be measured relatively quickly and accurately.
  • a single first dielectric layer and a single second dielectric layer are in general usually applied in the heating element according to the invention, it is likewise possible to envisage a plurality of first dielectric layers, preferably arranged on each other, and/or a plurality of second dielectric layers, preferably arranged on each other, being applied in the heating element.
  • the different first dielectric layers can herein be of differing composition and thickness. The same applies for the second dielectric layers in the case they are applied.
  • Additional sensor tracks and/or additional heating tracks can optionally be arranged between the different first dielectric layers (and/or second dielectric layers) in order to enable optimizing of the safety and/or the power of the heating element.
  • the heating track and the sensor track are preferably designed such that there is sufficient potential difference between the two tracks in operative mode to enable the forcing of a leakage current at sufficiently high temperature which flows from the heating track with a high potential to an adjacent part of the sensor track with a low potential.
  • the electrical resistance of the first dielectric layer is higher than the electrical resistance of the second dielectric layer at substantially the same temperature. Owing to the further increased electrically insulating action of the first dielectric layer relative to the second dielectric layer, an even more sensitive leakage current measurement is found to be possible. It is advantageous here when the first electric layer is situated closer to the surface for heating than the second dielectric layer. During overheating a leakage current will occur which will flow from the heating track to the adjacent sensor track via the second dielectric layer. The leakage current will here not flow via the first dielectric layer, or at least hardly so, which could result in a dangerous situation for a user of the heating element.
  • this preferred embodiment Owing to measurement or at least detection of the leakage current, combined if desired with a control of the heating element as already described above, in this preferred embodiment a very sensitive and rapidly responding protection against overheating is obtained.
  • This embodiment has the additional advantage here that the protection against overheating gains in reliability and can for instance withstand improper use. The operation of the protection is thus to a large extent insensitive to whether or not the heating element, and in particular the substrate for heating, is earthed.
  • a track configuration is usually also referred to as a bifilar track.
  • At least a part of the heating track and at least a part of the sensor track are preferably given a spiral form.
  • the shortest mutual distance between at least a part of the at least one heating track and at least an adjacent part of the at least one sensor track is here more preferably substantially constant, whereby a substantially parallel orientation of the heating track and the sensor track can be realized.
  • the shortest mutual distance between the heating track and the sensor track in position-selective manner in order to be able to predefine, and thereby optimize, the location of the occurrence of a leakage current.
  • the shortest mutual distance between at least a part of the at least one heating track and at least an adjacent part of the at least one sensor track lies between 100 ⁇ m and 800 ⁇ m, preferably between 400 ⁇ m and 600 ⁇ m, and more preferably amounts to substantially 500 ⁇ m.
  • the at least one heating track and/or the at least one sensor track are preferably coupled to a control unit.
  • a leakage current can on the one hand be detected and the heating element can on the other hand be (de)activated, and more preferably regulated.
  • the sensor track is coupled electrically to an ammeter and/or a voltmeter.
  • a leakage current can be detected in relatively simple and inexpensive manner by applying the ammeter and/or the voltmeter.
  • the ammeter and/or the voltmeter will here generally also take an earthed form in order to be able to detect a potential difference between the fixed world and the sensor track.
  • At least one electrically conductive element is arranged on the second dielectric layer.
  • the electrically conductive element such as for instance a layer of silver, may be arranged in position-selective manner on a side of the second dielectric layer remote from the heating track and the sensor track.
  • the electrically conductive element facilitates the flow of a leakage current between the heating track and the sensor track.
  • the electrically conductive element is also adapted to function as additional safety provision in the case the electronic regulation fails at sufficiently high temperature.
  • the electrically conductive element is adapted to be able to facilitate, and thereby guarantee, the flow of a leakage current from the heating track to a heating track with a lower potential when a critical temperature is exceeded.
  • the electrically conductive element for instance formed by a silver strip, in fact functions here as a bridge for the purpose of being able to facilitate the flow of a leakage current from the heating track to a (heating) track with a lower potential at sufficiently high temperature.
  • the temperature of the second dielectric layer will increase sharply locally due to the leakage current which flows from a heating track via the second dielectric layer, via the conductive element and once again via the second dielectric layer to a track, such as for instance a heating track or a (passive) sensor track, with lower potential.
  • a track such as for instance a heating track or a (passive) sensor track
  • the electrically conductive element at least partially crosses the heating tracks with differing potential (in a top view or bottom view of the heating element) in order to be able to limit the resistance between the heating tracks with different potential such that a leakage current will begin to flow between the heating tracks with differing potential when a critical temperature is exceeded.
  • the resistance of the second dielectric layer and the electrically conductive element will preferably be lower than the resistance of the first dielectric layer, so as to be able to ensure sufficient safety for a user.
  • the leakage current flowing from the heating track to the electrically conductive element could optionally also be detected, wherein the electrically conductive element can for instance be connected to a control unit, an ammeter and/or a voltmeter, whereby the electrically conductive element itself does in fact function as sensor element.
  • the shortest distance between the heating track and the electrically conductive element lies between 5 ⁇ m and 50 ⁇ m, preferably between 12 ⁇ m and 20 ⁇ m.
  • the heating track is at least partially protected by a sintered glass layer, preferably a sintered glass layer with a low melting point, more preferably a melting point lower than 450° Celsius.
  • a sintered glass layer preferably a sintered glass layer with a low melting point, more preferably a melting point lower than 450° Celsius.
  • the dielectric can be assembled from a dielectric layer of a polymer and a dielectric layer of enamel. Most preferably however, both dielectric layers are manufactured from enamel. Enamel compositions particularly suitable for this application are marketed under the name Kerdi. The use of an enamel layer as dielectric in the manufacture of, among other products, electrical heating elements is per se known, for instance from NL 1014601. The dielectric herein provides for electrical insulation of the electrical resistance, which generally consists of a metallic track. The manufacture of the dielectric from enamel results here in a mechanically relatively strong dielectric which conducts heat relatively well.
  • the composition of the enamel for both dielectric layers can be selected within wide limits, this subject to the desired electrical properties, particularly at temperatures occurring during use.
  • the specific electrical resistance of a common enamel composition is generally high at room temperature, usually higher than 1.5*10 11 ⁇ cm, but can fall drastically as temperatures increase to for instance a typical value of 1.5.10 7 ⁇ cm at 180-400° Celsius. A (relatively small) leakage current through the dielectric becomes possible at such a resistance.
  • the conductivity of an enamel composition can be readily adjusted by for instance making variations in the alkali metal content and/or by adding conducting or, conversely, electrically insulating additives.
  • the dielectric comprises a first and/or a second dielectric layer of an enamel composition and an electrically conductive layer which is assembled from metals and/or semiconductors and/or other conductive materials such as for instance graphite and so forth.
  • a heating element according to the invention which operates particularly well has the feature that the alkali metal content of the enamel composition of the first dielectric layer is lower than that of the second dielectric layer.
  • the manufacture of each layer of the dielectric from an enamel composition which differs only in the alkali metal content has the additional advantage that an optimal adhesion is achieved between the layers.
  • the difference in coefficient of expansion of the layers is moreover relatively small, so that the mechanical stresses in the material are minimized, which results in an improved durability of the dielectric, and therefore also of the heating element.
  • the breakdown voltage of such a layer is also important.
  • the breakdown voltage is the level of the electrical potential difference over the dielectric layer at which an electric current (with a much greater current strength than a leakage current) begins to flow through the layer. Breakdown can result in undesirable adverse effect on, and even irreparable disintegration of the dielectric layer and also the whole heating element.
  • the breakdown voltage of the dielectric must be sufficiently high in accordance with regulations of certifying organizations such as KEMA and ISO, preferably at least 1250 V (alternating voltage) relative to the earth.
  • the second dielectric layer By selecting the electrical resistance at a given temperature of the first dielectric layer significantly higher than that of the second dielectric layer, the second dielectric layer will at least partly transmit current at a given moment when the electrical resistance overheats. In such a case the first layer will transmit substantially no current, or in any case less.
  • the heating element according to the invention is therefore resistant to high voltage, even if the element continues heating at too high a temperature due to a failure of the electronic regulation or the switching member/relay connected thereto. During this process the electrical resistance track will then burn through (like a melting fuse) as a result of the above described conductive layer or sintered glass layer, and after this process the first dielectric layer ensures that a sufficient dielectric strength always remains relative to the earth or the consumer.
  • the heating element according to the invention is therefore intrinsically safe.
  • the breakdown voltage of a dielectric is determined by a plurality of factors, including among others the layer thickness of the dielectric, the enamel composition and structural defects such as gas inclusions and the like present in the dielectric.
  • a good adhesion of the dielectric layer, in this case the enamel composition on the surface for heating is also important.
  • a particularly suitable enamel composition for application in a dielectric layer of the heating element, preferably the first dielectric layer comprises between 0 and 10% by mass OfV 2 O 5 , between 0 and 10% by mass of PbO, between 5 and 13% by mass of B2O3, between 33 and 53% by mass of SiO 2 , between 5 and 15% by mass OfAl 2 O 3 , between 0-10% by mass of ZrO 2 and between 20 and 30% by mass of CaO.
  • the preferred composition also comprises between 0 and 10% by mass Of Bi 2 O 3 .
  • Such a composition results in an enamel layer with an improved durability when used in heating elements.
  • the enamel composition can be melted relatively easily and herein has a favourable viscosity, whereby it can be applied easily to different types of surface.
  • the enamel composition adheres particularly well to metals, in particular to steel, more particularly to ferritic chromium steel, and still more particularly to ferritic chromium steel with numbers 444 and/or 436 according to the American AISI norm.
  • the maximum compressive stress of the enamel layer which can be obtained from the enamel composition lies in the range between 200 - 250 MPa for the new composition.
  • the maximum compressive stress generally lies in the range of 70 - 170 MPa.
  • the preferred enamel composition furthermore has a high temperature resistance so that prolonged exposure to temperatures up to about 53O 0 C, with peak loads up to 700 0 C, does not cause problems.
  • a first dielectric layer on the basis of the preferred enamel composition therefore has little risk of breakdown, in other words is less susceptible to degeneration owing to prolonged load at a high voltage than known enamel compositions.
  • the properties of the enamel composition are furthermore such that the chance of crack formation in a dielectric layer manufactured therefrom is reduced in the case of temperature changes.
  • the preferred enamel composition has the additional advantage that dielectric layers with the desired properties can be applied to the surface for heating in small layer thicknesses. This enhances the heat conduction.
  • a particular preferred embodiment comprises a dielectric in which at least the lithium and/or sodium and/or potassium content of the first and the second dielectric layers differ from each other. It is advantageous herein if the enamel composition of the first dielectric layer is substantially free of lithium and/or sodium ions.
  • the second dielectric layer comprises at least lithium and/or sodium ions.
  • the enamel composition comprises between 0.1 and 6% by weight of potassium. Owing to the addition of potassium the load-bearing capacity of the adhesion of the enamel composition to the substrate surface is less critical. In an assembly of such an enamel composition with a substrate surface there occurs less deformation at increased temperatures, in particular in the case of overheating. This is particularly advantageous when the enamel composition is fired into a heating element.
  • the substrate for heating, on which the dielectric is arranged can be manufactured from any heat-conducting material.
  • the surface for heating is preferably manufactured substantially from metal, for instance steel and/or aluminium. Particularly advantageous is ferritic chromium steel, preferably with a chromium content of at least 10% by weight.
  • the coefficient of expansion of the material from which the surface for heating is manufactured does not differ too much from the coefficient of expansion of the first dielectric layer, for instance no more than 20 to 45%, for instance relative to steel, more preferably no more than 20 to 35%.
  • the coefficient of expansion of the second layer preferably does not differ any more than 0 to 25% relative to that of the first layer.
  • the coefficient of expansion of an enamel composition can be readily adapted to the coefficient of expansion of the surface for heating by for instance adjusting the alkali metal content. Adjusting the potassium content in the enamel composition is recommended here, since the leakage current is hardly influenced hereby at increased temperature. Conversely, it is also possible to choose another material for the substrate for heating.
  • the invention also relates to a liquid container provided with at least one heating element according to the invention.
  • the heating element according to the invention can be applied in many fields. It is thus possible to use the element in a water boiler, wherein electrical safety is provided for the user.
  • the heating element is also particularly suitable for application in steam generators, (dish-)washing machines, humidifiers, milk and other liquid heaters, pipe heating devices for liquids, cooker plates, grill plates and the like.
  • figure 1 shows a cross-section of a heating element according to the invention
  • figure 2 shows a bottom view of a part of the heating element according to figure 1
  • figure 3 shows the progression of the specific resistance of the first dielectric layer and second dielectric layer forming part of the heating element according to figure 1 as a function of the temperature
  • figure 4 shows the progression of the measured current strength as the temperature increases through dielectric layers of different enamel composition.
  • FIG. 1 shows a cross-section of a heating element 1 according to the invention.
  • Heating element 1 comprises a heating plate 2 for heating manufactured from ferritic chromium steel with a content of 18% by weight of chromium. It is also possible to apply another suitable metal or ceramic carrier, such as for instance decarbonized steel, copper, titanium, SiN, Al 2 O 3 and so forth.
  • a first dielectric enamel layer 3 is arranged on heating plate 2.
  • the first enamel layer 3 has an enamel composition substantially as according to column HT of Table 1.
  • a heating track 4 and a sensor track 5 running parallel to heating track 4 are arranged on the first, relatively electrically insulating enamel layer 3 in a substantially spiral-shaped pattern, wherein the distance between the tracks amounts to about 500 ⁇ m.
  • Heating track 4 and sensor track 5 are preferably manufactured from the same material, more preferably from silver, copper or an alloy of these or other metals, in order to be able to simplify and speed up the production process for the manufacture of heating element 1.
  • a second enamel layer 6 is arranged on top of and between tracks 4, 5, wherein a sintered glass layer 7 with a relatively low melting point is arranged crosswise over two or more of the heating tracks 4.
  • the enamel composition of second enamel layer 6 is selected within the limits indicated in column LTl of Table 1.
  • Arranged on second enamel layer 6 is a metal strip 8, in particular a silver strip, which extends over both heating track 4 and sensor track 5 to a different part of heating track 4 via the second dielectric layer.
  • Heating track 4 and sensor track 5 are electrically connected to a control unit 9.
  • Control unit 9 is adapted here to regulate the current strength through heating track 4.
  • Control unit 9 is coupled to a safety circuit 10 which can for instance be provided with a bimetal.
  • Control unit 9 is also coupled to an ammeter 11 for measuring the leakage current through sensor track 5.
  • Figure 2 shows a bottom view of a part of heating element 1 according to figure 1, in which the second enamel layer 6 is omitted from the figure for the sake of clarity.
  • Figure 2 clearly shows that heating track 4 and sensor track 5 are arranged in substantially spiral shape and substantially parallel to each other on first enamel layer 3.
  • Figure 2 also shows that silver strip 8 overlaps both sensor track 5 and heating track 4, in fact a plurality of heating track sections.
  • the operation of heating element 1 can be described as follows.
  • heating track 4 After activation of heating track 4 by control unit 9 heat will be generated in heating track 4, a substantial part of which heat is transferred to heating plate 2 via enamel layers 3, 6. Heating plate 2 will here generally be in contact with a liquid, to which the heat can then be relinquished. If however the heat developed by heating element 1 can no longer be transferred in adequate manner, the temperature of heating element 1 will rise.
  • the composition of second enamel layer 6 is chosen such that the resistance decreases significantly when a critical temperature is exceeded, such that a leakage current will begin to flow from heating track 4 to sensor track 5 via second enamel layer 6 and possibly also via silver strip 8. A leakage current flowing through sensor track 5 can be detected by ammeter 11.
  • Figure 3 shows the progression of the specific resistance of the first dielectric layer and second dielectric layer forming part of the heating element according to figure 1 as a function of the temperature.
  • the LTl and HT enamel compositions among others, ensure that the specific electrical resistance R6 of second enamel layer 6 decreases at a lower temperature than the specific electrical resistance R3 of the first relatively insulating layer 3.
  • the leakage current characteristic measured with the ammeter for a number of dielectric layers is shown in figure 4 as a function of the temperature T.
  • the leakage current I plotted on the vertical axis remains limited for relatively low temperatures T up to a point close to a determined initiating temperature, above which it suddenly increases rapidly.
  • the initiating temperature greatly depends on the composition of the enamel layer.
  • Figure 4 shows that the composition of the first layer, indicated with HT, has an initiating temperature which amounts to at least 500 0 C.
  • the other four shown leakage current characteristics are representative of enamel compositions of the second layer.
  • Table 1 preferred enamel compositions in heating element 1 according to the invention

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  • Resistance Heating (AREA)
  • Surface Heating Bodies (AREA)
  • Control Of Resistance Heating (AREA)

Abstract

L'utilisation d'émail en tant que couche intermédiaire diélectrique dans la fabrication d'éléments de chauffage est connue. L'invention concerne une couche d'émail diélectrique disposée ici sur un substrat dans l'ensemble métallique pour chauffer, les voies de chauffage métalliques sont disposées sur la couche en émail diélectrique par sérigraphie. L'invention concerne également un récipient pour liquide fourni avec un tel élément de chauffage.
PCT/NL2008/050360 2007-06-06 2008-06-06 Élément de chauffage et récipient pour liquide fourni avec un tel élément de chauffage WO2008150172A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN200880101804.3A CN101772985B (zh) 2007-06-06 2008-06-06 加热元件及装备有该加热元件的液体容器
EP08766783.8A EP2163130B1 (fr) 2007-06-06 2008-06-06 Élément de chauffage et récipient pour liquide fourni avec un tel élément de chauffage

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL2000685 2007-06-06
NL2000685A NL2000685C2 (nl) 2007-06-06 2007-06-06 Verwarmingselement en vloeistofhouder voorzien van een dergelijk verwarmingselement.

Publications (1)

Publication Number Publication Date
WO2008150172A1 true WO2008150172A1 (fr) 2008-12-11

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Family Applications (2)

Application Number Title Priority Date Filing Date
PCT/NL2008/050359 WO2008150171A1 (fr) 2007-06-06 2008-06-06 Elément chauffant et appareil électrique pourvu d'un tel élément chauffant
PCT/NL2008/050360 WO2008150172A1 (fr) 2007-06-06 2008-06-06 Élément de chauffage et récipient pour liquide fourni avec un tel élément de chauffage

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PCT/NL2008/050359 WO2008150171A1 (fr) 2007-06-06 2008-06-06 Elément chauffant et appareil électrique pourvu d'un tel élément chauffant

Country Status (4)

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EP (1) EP2163130B1 (fr)
CN (1) CN101772985B (fr)
NL (1) NL2000685C2 (fr)
WO (2) WO2008150171A1 (fr)

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WO2011158028A2 (fr) 2010-06-15 2011-12-22 Otter Controls Limited Dispositifs de chauffage de film épais
EP2720746A1 (fr) * 2011-06-16 2014-04-23 ResMed Limited Humidificateur et élément chauffant stratifié
WO2020201433A1 (fr) 2019-04-02 2020-10-08 Otter Controls Limited Générateur de vapeur
EP3610763B1 (fr) 2018-08-16 2021-04-07 CUP&CINO Kaffeesystem-Vertrieb GmbH & Co. KG Machine à café destinée à préparer une boisson chaude

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GB2470368A (en) * 2009-05-19 2010-11-24 Sagentia Ltd A glass kettle with a heating element comprising a film coating of semiconducting material
DE102012202379A1 (de) 2012-02-16 2015-08-13 Webasto Ag Fahrzeugheizung und Verfahren zur Überwachung einer Fahrzeugheizung
CN102685938A (zh) * 2012-05-05 2012-09-19 江苏正基仪器有限公司 耐磨防腐绝缘加热器托盘
CN104754788B (zh) * 2015-03-25 2016-05-25 国网山东省电力公司胶州市供电公司 节能电热玻璃板
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EP3281569B1 (fr) 2016-08-09 2018-07-04 CUP&CINO Kaffeesystem-Vertrieb GmbH & Co. KG Unité de moussage modulaire
US10917942B2 (en) 2017-07-31 2021-02-09 Samsung Electronics Co., Ltd. Structure, planar heater including the same, heating device including the planar heater, and method of preparing the structure
GB2576895B (en) * 2018-09-05 2021-02-17 Ferro Tech Bv Thick film resistor
JP2022534855A (ja) * 2019-06-06 2022-08-04 ヴィンセント メディカル（ドングアン）マニュファクチャリング シーオー．，エルティーディー． 改良されたヒータープレート
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WO2011158028A2 (fr) 2010-06-15 2011-12-22 Otter Controls Limited Dispositifs de chauffage de film épais
US9854626B2 (en) 2010-06-15 2017-12-26 Ferro Techniek Holding B.V. Thick film heaters
EP2720746A1 (fr) * 2011-06-16 2014-04-23 ResMed Limited Humidificateur et élément chauffant stratifié
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US9821135B2 (en) 2011-06-16 2017-11-21 Resmed Limited Humidifier and layered heating element
US10549064B2 (en) 2011-06-16 2020-02-04 ResMed Pty Ltd Humidifier and layered heating element
EP3714930A1 (fr) * 2011-06-16 2020-09-30 ResMed Pty Ltd Humidificateur avec élément chauffant en couches
US10940285B2 (en) 2011-06-16 2021-03-09 ResMed Pty Ltd Humidifier and layered heating element
US11504495B2 (en) 2011-06-16 2022-11-22 ResMed Pty Ltd Humidifier and layered heating element
EP3610763B1 (fr) 2018-08-16 2021-04-07 CUP&CINO Kaffeesystem-Vertrieb GmbH & Co. KG Machine à café destinée à préparer une boisson chaude
WO2020201433A1 (fr) 2019-04-02 2020-10-08 Otter Controls Limited Générateur de vapeur

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CN101772985B (zh) 2013-04-10
CN101772985A (zh) 2010-07-07
EP2163130B1 (fr) 2013-12-11
NL2000685C2 (nl) 2008-12-09
EP2163130A1 (fr) 2010-03-17

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