EP4053457A1 - Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité - Google Patents

Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité Download PDF

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Publication number
EP4053457A1
EP4053457A1 EP21160068.9A EP21160068A EP4053457A1 EP 4053457 A1 EP4053457 A1 EP 4053457A1 EP 21160068 A EP21160068 A EP 21160068A EP 4053457 A1 EP4053457 A1 EP 4053457A1
Authority
EP
European Patent Office
Prior art keywords
coating
cooking
cover element
cooking appliance
thermal radiation
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.)
Pending
Application number
EP21160068.9A
Other languages
German (de)
English (en)
Inventor
Marco Böckler
Klaus Wälzlein
Christoph Luckhardt
Aynur Gerede
Georg Pauli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electrolux Appliances AB
Original Assignee
Electrolux Appliances AB
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 Electrolux Appliances AB filed Critical Electrolux Appliances AB
Priority to EP21160068.9A priority Critical patent/EP4053457A1/fr
Priority to PCT/EP2022/053170 priority patent/WO2022184395A1/fr
Publication of EP4053457A1 publication Critical patent/EP4053457A1/fr
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/005—Coatings for ovens
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/32—Arrangements of ducts for hot gases, e.g. in or around baking ovens
    • F24C15/322—Arrangements of ducts for hot gases, e.g. in or around baking ovens with forced circulation
    • F24C15/325—Arrangements of ducts for hot gases, e.g. in or around baking ovens with forced circulation electrically-heated

Definitions

  • the present invention relates to a cooking appliance, in particular a domestic cooking oven.
  • US 2014/0110392 A1 discloses a baffle for directing air in a convection oven.
  • the baffle comprises vents and conduits to produce airflow throughout the cooking chamber and to evenly distribute cooking temperatures.
  • WO 2006/122118 A2 discloses radiant convection baffles for ovens that may comprise a fan, catalysts and a heater.
  • the fan is arranged to circulate air over the heater and the catalysts.
  • a support structure is formed to the baffle to deflect air circulated by the fan in opposite direction.
  • Baffles known in the art have slots, openings and gaps through which hot air can stream and which are subject to staining from contaminants solved in the hot air stream or moved by the hot air stream, such as hot fat drops, vapor or the like.
  • Such baffles are difficult to clean for a user of the cooking appliance, since the openings are difficult to be manually reached and remains of foodstuff previously cooked may adhere tenaciously to the surfaces of the baffle and/or to the cooking chamber walls.
  • the object of the present invention is to provide a cooking appliance that can be advantageously cleaned.
  • a cooking appliance in particular a domestic cooking oven, comprising:
  • the surface temperature of the second surface can be reduced under normal operation conditions of the cooking appliance. This results in a decreased temperature of the cover element and, consequently, in a decreased surface temperature of the first surface being directed to the cooking chamber. Therefore, by reducing the surface temperature of the first surface during operation of the cooking appliance, it is possible to coat the first surface with an easy-to-clean coating that is temperature sensitive and that does not tolerate a surface temperature above 300°C to 350°C. Reflectivity shall be understood as the ability of the surface to reflect a portion of the incoming radiation back from the surface. The portion of the radiation that is not reflected is absorbed by the body, i.e. the cover element.
  • the heating element is positioned within the hot air chamber and is configured such that at least a portion of the thermal radiation emitted by the at least one heating element hits the second surface of the cover element, wherein the second surface is configured to reflect at least 30% of the portion of the thermal radiation that hits the second surface.
  • the second surface reflects at least 30% if the incoming thermal radiation.
  • the second surface is configured to reflect at least 40% or at least 50%, in particular at least 55%, preferably at least 60% or at least 65% or at least 70% or at least 75% or at least 80% of the portion of the thermal radiation that hits the second surface.
  • Reflectivity for infrared or thermal radiation e.g. the reflectivity of a stainless steel material surface can be increased by providing a surface with increased gloss, e.g. by sanding and/or polishing. It has been found by the applicant that under normal operation conditions of a cooking oven, a second surface being provided as a stainless steel surface or as a surface having a comparable reflectivity for thermal radiation can reduce the surface temperature of the first surface by about 30°C to 40°C compared to a cast iron surface or a conventional enamel surface.
  • the reflectivity of a stainless steel surface without specific surface treatment is in the range of 50% to 55%.
  • the first surface has an emissivity for thermal radiation higher than an emissivity for thermal radiation of the second surface.
  • emissivity of a surface of a material is its effectiveness in emitting energy as thermal radiation.
  • Thermal radiation is electromagnetic radiation that may include both visible radiation (light) and infrared radiation, which is not visible to human eyes.
  • emissivity is the ratio of the thermal radiation emitted from a surface to the radiation emitted from an ideal black surface at the same temperature as given by the Stefan-Boltzmann law.
  • the emissivity of the first surface may be equal or higher than 0,7. Additionally or alternatively, the emissivity of the second surface may be equal or lower than 0,3.
  • Such a ratio of emissivity of the first surface and emissivity of the second surface results in a relatively high emissivity of the first surface. Consequently, the surface temperature of the first surface can be maintained relatively low under normal operation conditions of the cooking appliance, which allows the advantageous use of a temperature sensitive easy-to-clean coating on the first surface.
  • the second surface is provided as a coating-free surface, in particular as a surface of a steel material, preferably a polished steel material or a stainless steel material or a polished stainless steel material, or in particular as a surface of an aluminium material or an aluminium compound material.
  • the use of a stainless steel material allows preforming of the cover element from stainless steel and subsequent coating on the cooking chamber side of the cover element with an easy-to-clean coating.
  • the second surface may be provided by a coating.
  • the second surface may be provided by a coating having an emissivity equal or lower than 0,3.
  • the second surface may be provided by a coating applied to a steel material or an aluminium material or an aluminium compound material comprised by the cover element.
  • the coating may be an aluminium coating.
  • the cover element can be made from a cheaper material than stainless steel, e.g. from cast iron or another iron optionally having an enamel coating.
  • the coating having a low emissivity e.g. an aluminium coating which has also a high reflectivity for thermal radiation, may be applied to such a material.
  • the steel material or the aluminium material or the aluminium compound material comprised by the cover element may be coated by an intermediate coating, in particular comprising an enamel material or a ceramic base material or a non-stick and/or non-wetting coating material, forming a layer between the steel material or the aluminium material or the aluminium compound material and the coating forming the first surface, wherein the intermediate coating has a higher emissivity than the emissivity of the coating forming the first surface.
  • a cover element pre-fabrication of the cover element is enabled, wherein the cover element is provided from a specific material being coated with the intermediated coating, e.g. on the first surface side as well as on the second surface side. Subsequently, the coating, e.g. the aluminium coating, forming the second surface is applied on the hot air chamber side of the cover element only.
  • a cover element is achieved, that comprises a first surface formed by an enamel material or a ceramic base material or a non-stick and/or non-wetting coating material and a second surface formed by the coating having a low emissivity and being applied on the intermediate coating.
  • the first surface is provided by a coating comprising an enamel material or a ceramic base material or a non-stick and/or non-wetting coating material.
  • non-stick and/or non-wetting coating material which has easy to clean properties allows simple cleaning of the cover element.
  • the cover element may be arranged at a distance to the at least one heating element, wherein the distance is within a range from 2mm to 20mm, in particular within 4mm to 10mm, preferably within 5mm to 7mm, more preferably within 5mm to 6mm.
  • the surface temperature of the first surface may be further decreased by increasing the distance of the cover element from the heating element.
  • a large distance negatively affects the hot air generation within the hot air chamber.
  • the claimed ranges have been found to show the best results for a low surface temperature of the first surface and efficient hot air generation within the hot air chamber. Particularly advantageous is a distance between 5mm and 6mm.
  • a cover element comprising a sheet-like cover section separating the cooking chamber from the hot air chamber, wherein the thickness of the cover section is within a range of 0,3mm to 2mm, in particular within a range of 0,5mm to 1,2mm, preferably within a range of 0,5mm to 0,7mm.
  • the surface temperature of the first surface can be maintained in a range tolerable for an easy-to-clean coating.
  • Fig. 1 illustrates a cooking appliance 1 such as a domestic cooking oven comprising a cavity 2. Further commonly known parts of the cooking appliance 1 such as a housing, an operation panel and a door are not shown.
  • the cavity 2 defines a cooking chamber 4. Foodstuff to be cooking can be disposed within the cooking chamber 4.
  • a heating element 5 is arranged within the cavity 2 close to a rear wall of the cavity 2 being part of a cavity wall 3.
  • a cover element 6 is arranged within the cavity 2, separating the cooking chamber 4 from a hot air chamber 7 in which the heating element 5 is placed.
  • the heating element 5 is configured to heat up air within the hot air chamber 7 which can be conveyed from the hot air chamber 7 into the cooking chamber 4, e.g. by means a fan that may be arranged within the hot air chamber 7 or, alternatively, outside of the hot air chamber 7.
  • the cover element 6 comprises a first surface 6a and a second surface 6b, wherein the first surface 6a is directed to the cooking chamber 4 and the second surface 6b is directed to the hot air chamber 7.
  • the second surface 6b is configured to have a relatively high reflectivity for thermal radiation in order to reflect a large portion of the thermal radiation emitted by the heating element 5 and hitting the cover element 6. This has the effect that the surface temperature of the cover element 6 on the cooking chamber side, i.e. the surface temperature of the first surface 6a can be decreased.
  • the first surface 6a is configured to a have a high emissivity ⁇ 1 for thermal radiation. At least, the emissivity ⁇ 1 of the first surface 6a is selected to be higher than the emissivity ⁇ 2 of the second surface 6b. A particularly advantageous ratio has been found to be ⁇ 1 equal or higher than 0,7 and ⁇ 2 to be equal or lower than 0,3.
  • the technical effect of the first surface 6a having a relatively high emissivity ⁇ 1 is that the emission of thermal radiation of from the cover element 6 towards the cooking chamber 4 is high. During operation of the heating element 5, the cover element 6 is heated up and efficiently emits thermal radiation on the cooking chamber side. This also contributes in maintaining the first surface 6a at a relatively low surface temperature.
  • first surface 6a i.e. the cooking chamber side surface of the cover element 6 at a relatively low surface temperature allows the use of a temperature sensitive coating to be applied on the first surface 6a, such as an easy-to-clean coating.
  • An example for an easy-to-clean coating is a ceramic non-stick and/or non-wetting coating comprising at least a first and a second layer, wherein the first layer is applied to a pretreated substrate surface of the cover element 6 or a surface of a ground layer or a pretreated surface of a protective layer that is intended to be arranged on the cooking chamber side.
  • the second layer is applied to the first layer, so that a cover element 6 comprising a coating having base layer and top layer is obtained.
  • the second layer is obtained by a sol-gel process from a second composition comprising a silica sol, a silane and a siloxane, in particular a polydimethylsiloxane.
  • a coating having at least a second layer is also known from EP 2 177 580 B1 .
  • the second layer hereinafter also referred to as top layer, is composed of a matrix comprising the condensation reaction product of a silica sol, a silane and a siloxane. Obtained by a sol-gel process from a second composition has therefore to be understood in such a way, that the second layer is obtained by means of hydrolysis and (poly-)condensation of an aqueous mixture comprising at least a silica sol, a silane and a siloxane.
  • the starting materials of the second composition namely at least silica sol, silane, siloxane and water if needed, are mixed together and stirred. The mixture obtained thereof is then applied to the inner surface of the first layer and dried to obtain the second layer.
  • the silica sol is present in an amount of 15 to 70wt%, in particular in an amount of 30 to 70wt% and/or the silane is present in an amount of 2 to 70wt%, in particular in an amount of 10 to 40wt%, both in the first and/or the second composition and/or in the first and/or second layer.
  • silane in the first and/or the second composition and/or in the first and/or second layer is an organoalkoxysilane, in particular a methyltrimethyoxysilane and/or a fluoralkoxysilane.
  • the first and/or the second composition and/or in the first and/or second layer may comprise a catalyst, in particular an acidic catalyst, more preferably an organic compound containing one or more carboxyl groups and/or a mineral acid, e.g. hydrochloric acid, sulfuric acid or nitric acid.
  • a catalyst in particular an acidic catalyst, more preferably an organic compound containing one or more carboxyl groups and/or a mineral acid, e.g. hydrochloric acid, sulfuric acid or nitric acid.
  • a catalyst in particular an acidic catalyst, more preferably an organic compound containing one or more carboxyl groups and/or a mineral acid, e.g. hydrochloric acid, sulfuric acid or nitric acid.
  • a catalyst in particular an acidic catalyst, more preferably an organic compound containing one or more carboxyl groups and/or a mineral acid, e.g. hydrochloric acid, sulfuric acid or nitric acid.
  • the catalyst is present in an amount of 0,1 to 5 wt%, in particular in an amount of 0,1 to 2 wt%, both in the first and the second composition and/or in the first and/or second layer.
  • the catalyst generally acts as a catalyst in the hydrolysis and condensation reaction and prevents too slow crosslinking.
  • the first and/or the second composition and/or in the first and/or second layer comprise or comprises a solvent, in particular an organic solvent.
  • organic solvents are alcoholic solvents, for example methanol, ethanol or propanol.
  • the solvent is present in an amount of 10 to 60wt%, in particular in an amount of 10 to 40wt%.
  • the first composition or first layer may also comprise a siloxane in a preferred embodiment.
  • Said siloxane is in particular a polydimethylsiloxane.
  • An advantageous amount of siloxane in the first composition or first layer as well as in the second composition or second layer is between 0,1 to 2 wt%.
  • the first composition or first layer and/or the second composition or second layer may comprise pigments and/or dyes and/or filling materials and/or further additives.
  • temperature resistant anorganic pigments are favourable.
  • water may be added to the first composition and/or the second composition, if needed.
  • such a ceramic non-stick and/or non-wetting coating is able to tolerate a surface temperature of about 300°C to 350°C, but decomposes when being exposed to higher temperatures. Therefore, the first surface 6a of the cover element 6 is required to not exceed a surface temperature of 350°C or prefereably of 300°C.
EP21160068.9A 2021-03-01 2021-03-01 Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité Pending EP4053457A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP21160068.9A EP4053457A1 (fr) 2021-03-01 2021-03-01 Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité
PCT/EP2022/053170 WO2022184395A1 (fr) 2021-03-01 2022-02-09 Appareil de cuisson ayant un élément de couvercle à surface de réflectivité élevée

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21160068.9A EP4053457A1 (fr) 2021-03-01 2021-03-01 Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité

Publications (1)

Publication Number Publication Date
EP4053457A1 true EP4053457A1 (fr) 2022-09-07

Family

ID=74853579

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21160068.9A Pending EP4053457A1 (fr) 2021-03-01 2021-03-01 Appareil de cuisson ayant un élément de couverture comprenant une surface à haute réflectivité

Country Status (2)

Country Link
EP (1) EP4053457A1 (fr)
WO (1) WO2022184395A1 (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6004894A (en) * 1997-09-05 1999-12-21 Ferro Corporation Reflective porcelain enamel coating compositions
WO2006122118A2 (fr) 2005-05-09 2006-11-16 Adamski Joseph R Parois de four a rayonnement et convection
KR100821754B1 (ko) * 2006-11-29 2008-04-14 엘지전자 주식회사 오븐의 캐비티 구조
US20100006559A1 (en) * 2008-07-10 2010-01-14 Whirlpool Corporation Oven with improved functionality during grilling
EP2177580B1 (fr) 2008-10-16 2011-01-19 Looser Holding AG Couches antiadhésives
US20140110392A1 (en) 2012-10-22 2014-04-24 Miguel Estrella Oven baffle
EP3327358A1 (fr) * 2016-11-25 2018-05-30 Electrolux Appliances Aktiebolag Cavité ayant un revêtement d'émail, appareil de cuisson comprenant une telle cavité et procédé de fabrication d'une telle cavité

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6004894A (en) * 1997-09-05 1999-12-21 Ferro Corporation Reflective porcelain enamel coating compositions
WO2006122118A2 (fr) 2005-05-09 2006-11-16 Adamski Joseph R Parois de four a rayonnement et convection
KR100821754B1 (ko) * 2006-11-29 2008-04-14 엘지전자 주식회사 오븐의 캐비티 구조
US20100006559A1 (en) * 2008-07-10 2010-01-14 Whirlpool Corporation Oven with improved functionality during grilling
EP2177580B1 (fr) 2008-10-16 2011-01-19 Looser Holding AG Couches antiadhésives
US20140110392A1 (en) 2012-10-22 2014-04-24 Miguel Estrella Oven baffle
EP3327358A1 (fr) * 2016-11-25 2018-05-30 Electrolux Appliances Aktiebolag Cavité ayant un revêtement d'émail, appareil de cuisson comprenant une telle cavité et procédé de fabrication d'une telle cavité

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Publication number Publication date
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