WO2022184395A1 - Appareil de cuisson ayant un élément de couvercle à surface de réflectivité élevée - Google Patents

Appareil de cuisson ayant un élément de couvercle à surface de réflectivité élevée Download PDF

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Publication number
WO2022184395A1
WO2022184395A1 PCT/EP2022/053170 EP2022053170W WO2022184395A1 WO 2022184395 A1 WO2022184395 A1 WO 2022184395A1 EP 2022053170 W EP2022053170 W EP 2022053170W WO 2022184395 A1 WO2022184395 A1 WO 2022184395A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating
cooking
cover element
cooking appliance
cavity
Prior art date
Application number
PCT/EP2022/053170
Other languages
English (en)
Inventor
Marco Böckler
Klaus Wälzlein
Christoph Luckhardt
Aynur Gerede
Georg Pauli
Original Assignee
Electrolux Appliances Aktiebolag
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 Aktiebolag filed Critical Electrolux Appliances Aktiebolag
Publication of WO2022184395A1 publication Critical patent/WO2022184395A1/fr

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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 partic- ular 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 prolude airflow throughout the cooking chamber and to evenly dis- tribute cooking temperatures.
  • WO 2006/122118 A2 discloses radiant convection baffles for ovens that may comprise a fan, catalysts and a heater.
  • the fan is ar ranged to circulate air over the heater and the catalysts.
  • a support structure is formed to the baffle to deflect air circu lated 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 baf fles are difficult to clean for a user of the cooking appliance, since the openings are difficult to be manually reached and re mains 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 ap pliance that can be advantageously cleaned.
  • a cooking appliance in particular a domestic cooking oven, comprising:
  • a cavity comprising at least one cavity wall defining a cook ing chamber for cooking foodstuff therein and an opening for placing foodstuff into the cooking chamber, - at least one thermal radiation emitting heating element for heating said cavity, wherein the at least one heating element is arranged within said cavity adjacent to or in contact with the cavity wall, - at least one cover element being arranged within the cavity, wherein the cover element forms a partition wall between the cooking chamber and a hot air chamber in which hot air for heat ing the cooking chamber can be generated by heating the at least one heating element, the cover element comprises a first surface being directed to the cooking chamber and a second surface being directed to the hot air chamber.
  • the second surface comprises a reflectivity for thermal radiation that is higher than a reflectivity for thermal radiation of the first surface.
  • the surface temperature of the second surface can be reucked under normal operation conditions of the cooking appli ance. This results in a decreased temperature of the cover ele ment and, consequently, in a decreased surface temperature of the first surface being directed to the cooking chamber.
  • an easy-to-clean coating that is temperature sensitive and that does not tolerate a surface tem- perature above 300°C to 350°C.
  • Reflectivity shall be understood as the ability of the surface to reflect a portion of the incom ing radiation back from the surface. The portion of the radia tion 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 sur face of the cover element, wherein the second surface is config ured to reflect at least 30% of the portion of the thermal radi ation 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 reflec tivity 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 sur- face.
  • the reflectivity of a stainless steel surface without spe cific 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 radia- tion of the second surface.
  • emissivity of a surface of a material is its effectiveness in emitting energy as thermal radiation.
  • Thermal radiation is electromagnetic radia tion that may include both visible radiation (light) and infra- red 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 sur face 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
  • 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 op- eration conditions of the cooking appliance, which allows the advantageous use of a temperature sensitive easy-to-clean coat ing on the first surface.
  • the second surface is provided as a coating-free surface, in particular as a surface of a steel ma terial, 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 pre forming 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 com pound 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 ma terial 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 com- prising 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 dis tance 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 de creased 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 sur face temperature of the first surface and efficient hot air gen eration 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 is a cross-sectional side view of a cavity of a cooking appliance according to an exemplary embodiment of the invention
  • Fig. 2 is an enlarged view of the detail as indicated in Fig. 1;
  • 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 con veyed 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 Si for thermal radiation. At least, the emissivity Si of the first surface 6a is selected to be higher than the emis- sivity £ 2 of the second surface 6b. A particularly advantageous ratio has been found to be £iequal 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 £i is that the emission of thermal radiation of from the cover element 6 towards the cooking chamber 4 is high.
  • 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 sur face of the cover element 6 at a relatively low surface tempera ture allows the use of a temperature sensitive coating to be ap- plied 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 sec ond layer is applied to the first layer, so that a cover element 6 comprising a coating having base layer and top layer is ob tained.
  • 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 2177 580 B1.
  • the second layer hereinafter also referred to as top layer, is composed of a matrix comprising the condensa tion 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 composi tion 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.
  • the silane in the first and/or the second composi tion and/or in the first and/or second layer is an organoal- koxysilane, 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. hydro- chloric 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. hydro- chloric acid, sulfuric acid or nitric acid.
  • Different monocar- boxylic or dicarboxylic acids like formic acid, acetic acid or oxalic acid may be mentioned here as an example for suitable catalysts .
  • 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.
  • 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 metha- nol, 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 composi tion or first layer may also comprise a siloxane in a preferred embodiment.
  • Said siloxane is in particular a polydimethylsilox- ane.
  • 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 composi tion or second layer may comprise pigments and/or dyes and/or filling materials and/or further additives. In particular, tem perature 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
  • the first surface 6a of the cover element 6 is re quired to not exceed a surface temperature of 350°C or preferea- bly of 300°C.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electric Stoves And Ranges (AREA)

Abstract

Appareil de cuisson (1), en particulier un four de cuisson domestique, comprenant : - une cavité (2) comprenant au moins une paroi de cavité définissant une chambre de cuisson (4) pour cuire des aliments à l'intérieur de celle-ci et une ouverture pour placer des aliments dans la chambre de cuisson (4), - au moins un élément chauffant émettant un rayonnement thermique (5) pour chauffer ladite cavité (2), le ou les éléments chauffants (5) étant disposés à l'intérieur de ladite cavité (2) adjacents à la paroi de la cavité ou en contact avec celle-ci (3), - au moins un élément de recouvrement (6) étant disposé à l'intérieur de la cavité (2), l'élément de recouvrement (6) formant une paroi de séparation entre la chambre de cuisson (4) et une chambre d'air chaud (7) dans laquelle de l'air chaud pour chauffer la chambre de cuisson (4) peut être produit par chauffage du ou des éléments chauffants (5), l'élément de recouvrement (6) comprenant une première surface (6a) étant dirigée vers la chambre de cuisson (4) et une seconde surface (6b) étant dirigée vers la chambre d'air chaud (7), caractérisé en ce que la seconde surface (6b) comprend une réflectivité pour un rayonnement thermique qui est supérieure à une réflectivité pour un rayonnement thermique de la première surface (6a).
PCT/EP2022/053170 2021-03-01 2022-02-09 Appareil de cuisson ayant un élément de couvercle à surface de réflectivité élevée WO2022184395A1 (fr)

Applications Claiming Priority (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
EP21160068.9 2021-03-01

Publications (1)

Publication Number Publication Date
WO2022184395A1 true WO2022184395A1 (fr) 2022-09-09

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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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