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
  • F24C15/08—Foundations or supports plates; Legs or pillars; Casings; Wheels
• • 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
  • F24C15/36—Protective guards, e.g. for preventing access to heated parts

Definitions

• the present invention relates to electric cooking appliances of the oven type enclosing a cooking enclosure inside which are arranged heating means of the radiant type, essentially in the infrared.
• the present invention relates in particular to ovens which can be placed on a table, as opposed to so-called "built-in” ovens.
• Floor-standing ovens are ovens of very variable capacity, ranging from ten liters to almost 40 liters, but which generally all have cooking temperatures of up to 250 ° C inside the cooking chamber .
• the present invention relates to ovens comprising means for heating the air of the enclosure and the food therein by heating elements radiating in the infrared, which can be supplemented by means of stirring the air. . Such ovens therefore see the temperature of their walls rise, in contrast to microwave ovens in particular.
• Document FR 2 732 097 describes in particular a cooking oven door comprising a frame on which are mounted an internal glass wall and an external plastic wall, said door comprising ventilation means between the two walls in order to reduce the temperature of the outer wall.
• the present invention aims to reduce the risk of burns by contact with the external parts of a household appliance operating by radiation and convection, by using simple and inexpensive means.
• the present invention is achieved by means of an electric household cooking oven comprising an enclosure delimited by two lateral faces, a vault face, a sole face and a rear face, main heating means of the radiant type, essentially emitting in the infrared, arranged in the enclosure, said oven comprising a covering surrounding for the most part the enclosure at the level of the lateral faces and of the arch face, the front face of the oven being equipped with a door and a control panel, characterized in that the oven comprises means limiting heating of the covering of the oven.
• the lowering of the temperature of the lining of the oven makes it possible to use a material which is not very resistant to heat, a material generally of low cost.
• the covering also covers the major part of the rear face of the cooking enclosure. Indeed, although the rear face of the oven is less accessible than the side faces and the upper face, it is advantageous that the covering also covers a significant part of the rear face of the enclosure in order to minimize the risk of burns.
• the means limiting overheating of the lining of the oven comprise confinement by partitioning of the space separating the vault from the enclosure of the upper part of the lining.
• confinement must therefore be understood and interpreted as confining or isolating the volume of air located between the vault of the enclosure and the roof of the cladding.
• This confinement can be obtained in various ways, in particular by not providing no ventilation opening in the covering, in particular at the level of the roof and of the parts of the side walls located at and above the vault of the enclosure, thus minimizing air circulation.
• an air circulation in the volume located between the vault of the enclosure and the covering roof causes an increase in the temperature of said roof, by the mixing of the air produced.
• hot spots are then generated at the openings of the covering, locally increasing the temperature, and which can lead to degradation of the material used to make the covering.
• This closure of the space is not, however, watertight but is understood qualitatively as a maximum limitation of air exchanges with the outside. Thus, the residual construction openings do not participate significantly in the heat exchange with the outside.
• An improvement in this confinement of the space above the vault consists in providing a peripheral rim at the vault face of the enclosure.
• a heat shield is disposed in the confinement space, between the upper part of the covering and the vault of the enclosure, making it possible to further reduce the temperature of the roof of the covering.
• the heat shield covers at least the entire surface of the enclosure vault.
• the heat shield has vertical walls inclined downward and extending, at the side faces and the rear face, up to the covering of the oven, thus making it possible to create a double partitioning of the air. , on the one hand between the vault of the enclosure and the heat shield, and on the other hand between the heat shield and the covering of the oven.
• a spacer made of a material of low thermal conductivity (for example less than 1 W m "1 K “ 1 ) is disposed substantially in the middle of the thermal screen, extending on both sides and d 'other of said screen, perpendicular thereto, on the one hand up to the vicinity of the enclosure vault, and on the other hand up to the covering.
• This spacer thus makes it possible to keep a minimum distance between on the one hand the vault of the enclosure and the thermal screen, but also between the roof of the covering and said thermal screen.
• a metal strip is disposed substantially perpendicular to the door, over at least the length of the cooking chamber, said strip being connected to the covering by an insulating rod.
• the arrangement of a metal strip above the oven door makes it possible to locally absorb the rising heat from the oven at the door level, thus constituting overall a thermal brake to the increase in temperature of the covering.
• the metal strip has fine openings to promote the exchange of calories between the interior of the enclosure and the exterior and thus increase the thermal brake effect. These fine openings in the upper part and at the front of the oven are however sufficiently thin and eccentric not to cause a consequent mixing of the air or an air circulation.
• the insulating rod has a local thermal brake function between the metal zone and the covering.
• this rod is made of heat-resistant plastic, such as poly (butanediole terephthalate-1, 4), more commonly known as PBT.
• heat-resistant is meant a material retaining good mechanical properties when its temperature increases, and this over a large temperature range.
• engineering plastic is commonly used to characterize such materials.
• the covering of the oven is made of plastic of the thermoplastic type.
• thermoplastic material such as for example polypropylene (PP)
• PP polypropylene
• the use of a plastic material also brings the advantage of having a contact temperature between the skin and this material lower than it would be with a usual coating of enamelled or coated sheet metal, for the same temperature of dressing. This is due to the difference between the effusives PP and metallic materials such as steel.
• the contact of the skin with this coating will be established at a lower temperature if the coating is made of PP rather than enamelled or coated sheet metal for example.
• plastic allows molding operations that can be easily automated and which allow greater freedom in product design.
• FIG. 1 is an exploded perspective view of the various constituent elements of the oven according to the invention
• FIGS. 2 and 3 are partial views of the front face of the oven
• FIG. 4 is a view along section A-A of FIG. 2,
• FIG. 5 is an enlarged view of Figure 4 along the indicated circle.
• the oven 1 comprises, as it is known, a cooking enclosure 2 composed of five sheets defining the faces 4a to 4e, said sheets being assembled by forming an open parallelepiped volume in the front.
• a door not shown, is disposed at this opening and closes the volume of the enclosure.
• the side faces 4a, 4b have grooves 6 for positioning a cooking grid.
• the control portion of the oven, not shown, is attached to the face 4b, outside the enclosure.
• the horizontal faces of vault 4c and sole 4e respectively comprise stamped bosses 8 and 10 which make it possible to maintain heating resistors 32, visible in FIGS. 2, 4 and 5, at a distance from the surface of said faces.
• the sole bosses 10 also include hooks 12 for fixing the resistance.
• the arch face 4c is bordered by a peripheral rim 14, either from said face, by folding, or from the lateral faces.
• This enclosure is arranged on a base, not shown, which may be made of metal or in technical plastic of the PBT type resistant to high temperatures, as previously explained.
• the base can be made of PP with PBT supports.
• the oven comprises a covering 16 of the enclosure composed of four walls 18a to 18d.
• This covering is to cover the faces of the cooking chamber, except the horizontal face of the 4th floor.
• this covering has no openings or gills, as it is frequently encountered in commercial ovens.
• the face 18c forming the roof of the covering creates, with the rim 14 and the beginning of the vertical faces, a partitioning which creates a confinement of the space situated above the vault 4c of the enclosure.
• the walls 18a and 18b have a return 19 towards the front face of the oven, making it possible to mask the internal edges of the metal carcass while giving the oven a homogeneous shape.
• This oven covering is placed on the base supporting the enclosure, by means of locking clips 40 coming to be positioned in suitable housings made in said base.
• the contact zones between the enclosure and the base are as far as possible from the clip attachment areas.
• the sheet metal of the enclosure is cut at the level of the contacts with the base to minimize the thermal bridges between the enclosure and the base.
• the base has significant vertical walls, further limiting the heat transfer from the base to the covering.
• a heat shield 20 is arranged between the roof 4c of the enclosure and the roof 18c of the covering.
• This heat shield covers the entire surface of the vault of the cooking enclosure and even extends beyond the wall 4b above the oven control part.
• This heat shield 20 also has parts folded at the ends of its four edges, and folded down.
• the lateral parts 22a and 22b, as well as the rear part 22d, visible in FIGS. 2 and 3, are quite long and extend up to the covering, coming to be positioned on locking tabs 34. This allows them to protect effectively the respective walls 18a, 18b and 18d of the covering by closing the hottest space at the top of the enclosure, while ensuring the correct positioning of the screen relative to the covering.
• the front part 22c is shorter and is positioned against the front rim 14, which allows a predetermined distance between the vault 4c of the enclosure and the thermal screen 20 and reinforces the partitioning of the space between the reflector and enclosure.
• a cylindrical spacer 24 is positioned in an opening 26 of the heat shield, substantially in the middle of the latter.
• This spacer 24 has a recess in its diameter so as to present a bearing surface for its positioning on said heat shield.
• the spacer 24 thus extends on either side of the heat shield 20, to come into contact in particular with the roof 18c of the covering.
• a play is left with the vault 4c of the enclosure, essentially to avoid creating a thermal bridge with this surface which is brought to high temperature during the operation of the oven.
• this game makes it possible to compensate for differences in tolerances on the parts, in order to ensure mounting of the covering without deformation of said covering and / or of the heat shield.
• this spacer serves as mechanical reinforcement to the roof 18c of the covering and prevents a heavy object placed on the roof from creating a significant deformation of the covering.
• this spacer is made of a material having a low thermal conductivity.
• a material such as plastic fulfills these conditions, having a thermal conductivity of the order of 0.2-0.3 W m "1 K " 1 . This plastic will however have to resist high temperatures, since the contact with the vault of the enclosure is possible.
• heat-resistant pads made of thermoplastic or thermosetting material compatible with these temperatures and having a low thermal conductivity, for example less than 1 W m "1 K " 1 .
• the heat shield descends sufficiently low along the enclosure so that it is not necessary to use a heat-resistant plastic, in particular for the production of the support legs 34 of the screen, made also in PP.
• the covering of the oven comprises a strip 28 plumb with the oven door.
• This strip is metallic and is connected to the plastic covering by two insulating rods 30, 31.
• the temperature can suddenly increase and reach high values when the door is half open or when the seal is defective, or even in the absence of a seal.
• the limitation of the rise in temperature of the covering can then be achieved by multiplying the thermal screens and by increasing their quality.
• connection between the rod and the strip as well as between the rod and the plastic covering are such that the number of contact points is limited to the number necessary to ensure mechanical positioning without local creep of the materials at the contact points, and thus limit transfer by thermal conduction. Special care should be taken to keep the contact points between the strip and the ring as far away as possible from the contact points between the ring and the covering in order to minimize heat transfer from the strip to the cover via the ring.
• the strip comes to bear on and under the rim 14 on the front face of the oven, by producing a recess 36 on which the door is pressed in the closed position. In this way, the calories escaping through the front face of the cooking chamber, not shown, are inevitably collected by said strip.
• FIG 4 clearly shows that the spacer keeps the heat shield 20 substantially midway between the vault 4c of the cooking chamber and the roof 18c of the covering.
• the roof 18c of the covering is curved, which ensures better mechanical stability of said covering when it is brought to a certain temperature.
• the wall of the reflector and the walls of the enclosure opposite the covering may be treated to minimize the emission by radiation, either by mechanical treatment and / or a specific coating, as is known in the art. field. It will then be ensured that the thermal emissivity coefficient is less than 0.3 for the faces considered and for temperatures between 150 ° C and 300 ° C.
• the heat generated by the heating resistors 32 is essentially reflected by the heat shield 20, or even partly absorbed by the metal strip 28 when it is present.
• Air confinement at above the vault of the enclosure by considerably limiting the air movements, in particular by reducing the air inlets to assembly leaks, makes it possible to considerably reduce the temperature of the covering 16 of the oven.
• the thermal effusiveness of steel is around 14000 W m 2 K "1 s 1/2 .
• the PP has an effusivity around 400 W m 2 K " 1 s 1/2 , while that of the skin is close to 1800 W m 2 K "1 s 1/2 .
• Ti and ⁇ are the temperature and thermal effusivity of solid 1 (respectively of solid 2).

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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)
• Disintegrating Or Milling (AREA)
• Control And Other Processes For Unpacking Of Materials (AREA)
• Vending Machines For Individual Products (AREA)
• Glass Compositions (AREA)
• Surgical Instruments (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

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Family Applications (1)

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Families Citing this family (3)

Family Cites Families (16)

• 2002
  • 2002-01-30 FR FR0201101A patent/FR2835310B1/fr not_active Expired - Fee Related
• 2003
  • 2003-01-29 RU RU2003131891/03A patent/RU2003131891A/ru not_active Application Discontinuation
  • 2003-01-29 WO PCT/FR2003/000272 patent/WO2003064930A1/fr active IP Right Grant
  • 2003-01-29 ES ES03715064T patent/ES2272964T3/es not_active Expired - Lifetime
  • 2003-01-29 AT AT03715064T patent/ATE344909T1/de not_active IP Right Cessation
  • 2003-01-29 EP EP03715064A patent/EP1470371B1/de not_active Expired - Lifetime
  • 2003-01-29 US US10/503,077 patent/US20050072770A1/en not_active Abandoned
  • 2003-01-29 DE DE60309563T patent/DE60309563T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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