WO2006048748A2

WO2006048748A2 - Oven with improved arrangement of the internal elements

Info

Publication number: WO2006048748A2
Application number: PCT/IB2005/003306
Authority: WO
Inventors: Luciano Antonini; Jean Claude Chapelier; Mirco Milanese; Renato Longo
Original assignee: Indesit Company S.P.A.
Priority date: 2004-11-08
Filing date: 2005-11-07
Publication date: 2006-05-11
Also published as: EP1819966A2; ITTO20040767A1; RU2007121450A; WO2006048748A3; RU2382280C2

Abstract

A pyrolitic oven is described, which comprises a muffle delimiting a cooking compartment wherein food can be placed through an aperture which can be closed by means of a door, a container containing said muffle, and control means being external to said muffle and adapted to control the temperature inside the cooking compartment. According to the invention, said control means are located in the lower half of said container, preferably on the base of said container.

Description

OVEN WITH IMPROVED ARRANGEMENT OF THE INTERNAL ELEMENTS

DESCRIPTION

The present invention relates to a pyrolitic oven according to the preamble of claim 1. Nowadays a plurality of pyrolitic ovens are known; the size of those for domestic use is almost standardized, due to the necessity of installing built-in ovens into a recess of a kitchen cabinet. Except for craftworks, the standard sizes of said recess are 60 cm width x 60 cm height x 60 cm depth, or 90 cm width x 60 cm height x 60 cm depth.

Such dimensions derive from two main factors: the furniture manufacturers' habit of working with multiples of 12 cm and the necessity, imposed by the market, of having an oven cooking compartment which volume is approximately 50 It or higher. In the most widespread solutions, the pyrolitic oven comprises three elements: an upper grill element positioned inside the cooking compartment, a circular element for ventilated cooking, and a lower element typically positioned within a housing under the muffle. Through said element it is possible to carry out different types of cooking and to perform a pyrolisis process wherein the oven temperature is brought to approximately 500 ⁰C in order to carbonize all food residues forming the dirt and which are typically deposited on the walls of the cooking compartment. In these types of ovens, the presence of title lower element obliges to locate the electronics of the oven above the muffle; as a matter of fact, no room is available under the muffle due to the presence of the lower element, while behind the muffle there are the terminals of the lower element, which become very hot, but there is some space available above the muffle, due to the presence of the control panel of the oven, wherein the control electronics may be placed. This area is however relatively hot because of the heat generated by the element terminals extending into said container.

Patents GB 2 325 299, GB 1 455 838 and US 6,730,881 describe pyrolitic ovens fitted with just two elements: an upper element for the grill and a circular element for ventilated cooking. Notwithstanding the absence of the lower element, in the Patents GB 2 325 299 and US 6,730,881 the oven control electronics is still located above the muffle.

As shown in Fig. 1, according to the Patent GB 1 455 838 the control electronics is located behind the muffle, in direct contact with the grill element; the reasons for such an illogical positioning of the control electronics are not described. In all known solutions, therefore, the control electronics is located in a relatively hot zone of the oven, so that the control electronics must be adapted to operate at relatively high temperatures of approximately 75°C, or else cool fans must be provided.

In the case of the Patent GB 1 455 838, wherein the control electronics is very close to the grill element, the operating specifications required are necessarily very severe; as a matter of fact, the control electronics turns out to be very expensive; de facto this solution cannot be implemented due to its costs.

For the purpose of positioning the control electronics in a less hot area, the Patent Application

WO 97/26486 discloses the idea of locating almost the entire electronics and the control panel inside the handle of the door of the oven cooking compartment. The only exception, due to safety reasons, is represented by the power electronics, which is part of the control electronics and manages the energy supply. This solution offers the advantage of eliminating the encumbrance of the control panel, but it does not teach how to obtain a reduction of the oven dimensions, for it does not indicate where the power electronics should be located.

A first object of the present invention is therefore to find a better position for the control electronics, thereby allowing less restrictive operating specifications for said electronics.

Considering that in any known oven which can be manufactured at low costs the position of the control electronics does not allow to reduce the overall dimensions of the oven, another object of the present invention is to provide a pyrolitic oven characterized by low costs and reduced dimensions. In particular, such a size reduction must be achieved without affecting the capacity of the cooking compartment, which must remain of approximately 50 It.

Another object of the present invention is to provide a multifunction pyrolitic oven having just two elements and compensate for the absence of the lower element.

These and other objects are achieved by means of a pyrolitic oven incorporating the features of the annexed claims, which form an integral part of the present description. Further objects and advantages will become apparent from the following detailed description and annexed drawings, supplied by way of non-limiting example, wherein:

Fig. 1 shows a kitchen cabinet and an oven being built-in.

Fig. 2 shows an open oven.

Fig. 3 shows a vertical cross-section of an oven according to the prior art. Fig. 4 shows a vertical cross-section of an oven according to the invention.

Fig. 5 shows a front view of an oven according to the invention, with the door closed.

Fig. 6 shows an embodiment of a fan guard according to the invention. In the following description and in the annexed drawings, corresponding items will be referred to the same reference number.

Fig. 1 shows a kitchen cabinet 1 in which a refrigerator 2 is built-in; Fig. 1 also shows an oven 3 made according to the prior art being built-in inside a recess 4 of the cabinet. The oven 3 is fitted with a control panel 5 comprising knobs 6 and a display 7 through which the user can select the cooking parameters, in particular temperature and time, and possibly preset cooking programs as well.

Fig. 1 also shows the container 8 which encloses the rear portion of the oven, while in front there is a door 9 provided with a handle 10 and an inspection glass 11. Fig. 2 shows a front view of the oven 3 with the door 9 open. In this illustration it is visible the muffle 12 defining a cooking compartment 13 in which the food to be cooked can be placed; reference number 26 shows a baking pan positioned inside the cooking compartment. Fig. 3 shows a vertical cross-section of an oven according to the prior art; inside the muffle there are a grill element 14 close to the muffle top and a circular element 15 on the side opposite to the door 9.

Inside the muffle 12 there is also a fan 16 operated by a motor 17; the fan is mounted with its rotation axis being concentric to the circular element 15, therefore when the element is heated the rotating fan will generate a hot air flow inside the oven. For safety reasons, the fan is located behind a guard 18 consisting of a perforated panel mounted on the vertical side of the muffle.

The control panel 5 is connected through cables 19 to the control electronics 20, which controls, through electric connections 21, the activation of the fan 16 and the power supplied to the elements, so as to adjust the temperature inside the oven. By appropriately sizing and controlling the elements it is possible to obtain, in a known way, a pyrolisis process in the oven.

Particularly during this process, high current passes through the elements and dissipate much heat in order to bring the temperature inside the cooking compartment to approximately 500 ⁰C. Despite the muffle insulation, the terminals of the elements 14 and 15, which extend outside the muffle for establishing the necessary electric connections, warm up the air within the container 8. The control electronics 20 therefore operates at relatively high temperatures; in ventilated ovens, the control electronics must typically be sized to operate at 75 °C. According to the invention, in order to guarantee a better or the same efficiency of the control electronics or, to allow to manufacture said electronics according to less restrictive specifications, the pyrolitic oven comprises a muffle delimiting a cooking compartment wherein food can be placed through an aperture which can be closed by means of a door, a container containing said muffle, and control means being external to said muffle and adapted to control the temperature inside the cooking compartment, and is characterized in that said control means are located in the lower half of said container, preferably near the base of said container.

A vertical cross-section of a pyrolitic oven according to the invention is shown in Fig. 4. The control means 22 are located behind the muffle 12 and rest on the base of the container 8, in an area of the oven being cooler than the high portion of the container.

In the pyrolitic oven according to the invention, the control means 22 are adapted to adjust the power of a first element 15, being preferably circular, which is located on the side opposite to said aperture, and of a second grill element 14 which is located close to the top of said muffle. According to a preferred embodiment, said first element and said second element are the only elements adapted to heat the inside of said cooking compartment; in a possible variant, it may be provided that, for instance, the second grill element consists of two distinct elements being controllable independently by said control means.

For the purpose of providing the control functionalities of the heating elements 14 and 15, the control means 22 comprise power circuits, one or more logic units, in particular a microcontroller, and a plurality of memories, e.g. ROM, RAM, EEPROM.

Since the control means 22 are located under the elements 14 and 15, they are less affected by the heat generated by the same elements inside the container.

In order to improve the cooling of the oven and of the control means, according to the invention the oven also comprises cooling means, in particular a fan 23 being external to said muffle and located in the upper half of said container; said cooling means adapted to draw air F from outside said container and to make air circulate inside said container 8. The rotation of the fan 23 being external to the muffle generates an air flow F which is drawn from outside the oven through a number of apertures 24 obtained in the base of the container 8 and then delivered outside of the oven through a duct 25 running above the muffle 12. According to this embodiment, air at room temperature is drawn and gets in contact with the control means, thereby cooling them. With respect to the prior art, it is thus obtained a better efficiency in cooling control means, as the control means are cooled by air at room temperature and not by air previously warmed up inside the oven container.

In order to improve the cooling efficiency even further, the control means may be inserted in a dedicated container, preferably a metallic one, fitted with air passage slots and located immediately above an aperture 24 in the base of the container 8. The position of the control means in an oven according to the invention also allows to reduce the number of elements positioned above the muffle; one of these elements is the control panel, which is a user interface device adapted to the selection of the functions of said oven; knobs 6 or push-buttons and a display 7 are employed for this purpose.

According to the invention, said interface device 27 is connected to the control means 22 through electric cables or optical fibers or by radio.

Advantageously, said user interface device 27 is located in such a way as to remove a further element from above the muffle and thus be able to reduce the overall dimensions of the oven 3 without decreasing the capacity of the muffle 12.

In the preferred embodiment shown in Figs. 4 and 5, said user interface device 27 is inserted in a handle 10 associated with the oven door 9. According to a preferred embodiment, said user interface device may also be separated from said oven and used remotely; in this embodiment, the oven according to the invention is therefore provided with a housing, e.g. inside the oven handle, in which said user interface device can be inserted. Such a housing comprises an electronic board fitted with electrical, optical or radiofrequency contacts adapted to connect said interface device 27 to said control means 22 when said device is inserted in the housing, as well as interfaces, in particular radio or infrared ones, adapted to connect said board to said interface device when the latter is separated from the oven.

Advantageously, said user interface device may be a remote control unit directly communicating with said control means through a radio connection. The above teachings referring to the user interface device are not strictly bound to the position of the control means. In this sense, an oven comprising a muffle 12 delimiting a food cooking compartment, a container 8 containing said muffle 12, control means 22 adapted to control the operation of said oven, and a user interface device 17 connected to said control means 22 and adapted to select the operation of said oven may be characterized in that said user interface device 27 can be separated from said oven and used remotely, and that, preferably, the width and height of said container 8 are substantially equal to the width and height of said muffle. In a known manner, the pyrolitic oven according to the invention comprises an internal fan 16 mounted close to the circular element 15 and adapted to generate a hot air flow inside said muffle. Said oven also comprises a guard 28 adapted to avoid the risk of unintentional contact with said internal fan. Experiments and simulations carried out by the Applicant of the present Patent have shown that pyrolitic ovens having just two elements, like those described above, imply some problems related to the necessity of bringing the lower surfaces of the cooking compartment to an acceptable temperature for the pyrolisis. As a matter of fact, the absence of the lower element makes it difficult to bring the base of the cooking compartment to 500 °C in order to carbonize, and therefore effectively remove, food residues.

In order to improve the efficiency of a two-element oven, the oven may comprise diverting means adapted to direct the most part, preferably at least 50%, of the air flow generated by the fan in the muffle toward the base of said cooking compartment. In particular, the oven may comprise flow diverters, e.g. simple metal panels, which direct the hot air flow generated by the fan 16 in the muffle toward the base of the cooking compartment. Said means used for diverting the air flow may, as an alternative o in addition, comprise the guard of said internal fan 16.

For the purpose of directing the air flow toward to base of the cooking compartment, according to a preferred embodiment the fan guard comprises a panel 28 being polyhedric, preferably substantially cylindrical, in shape and mountable to or integrated with a first wall of the cooking compartment being opposite to the oven's aperture; according to the invention, said panel has:

- at least a first face positioned toward said aperture, and a side surface connecting said first face to said first wall of the cooking compartment, - a plurality of apertures 29 and 30 being present on said first face and along said side surface.

According to the invention, at least 50% of the overall surface of the apertures along the side surface of the polyhedron is contained in the polyhedron half facing the base of the cooking compartment. In a preferred embodiment shown in Fig. 6, said panel is substantially cylindrical in shape and is mounted with its base being parallel to the oven's aperture; the panel is provided with apertures 29 and 30 being present solely in said base and in the lower half of the side surface of said cylinder.

In the embodiment shown in Fig. 6, the apertures 29 along the side surface are bigger than those being present in the base 30, in particular at least one of said apertures covers an area of a few cm , e.g. more than 3 cm . In an oven fitted with a fan guard, e.g. like the one shown by way of example in Fig. 6, which is substantially closed along the side surface facing the top of the cooking compartment and has large apertures 29 along the side surface facing the base of the cooking compartment, the rotation of the fan 16 in the muffle generates an air flow C which escapes through the apertures 29, runs along the side surfaces and enters again through the apertures 30 on the base.

Fig. 6 clearly shows how the shape of the apertures along the side surfaces of the guard allows to direct the hot air flow generated by the fan toward the base of the cooking compartment. The teachings of the present Patent Application allow to manufacture a pyrolitic oven fitted with a muffle having a volume of approximately 50 It and being built-in into a recess of a cabinet having at least a side measuring 48 cm. In fact, the oven according to the invention still uses a muffle 12 having the standard dimensions of a built-in oven, while the removal of the lower element, the positioning of the control means 22 on the base of the container 8 rather than above the muffle and the contemporary removal of the control panel from the front side of the oven allow, the muffle height being equal, to reduce the vertical dimensions of the oven. Such a reduction may de facto be as large as 12 cm.

Claims

1. Pyrolitic oven comprising a muffle (12) delimiting a cooking compartment wherein food can be placed through an aperture which can be closed by means of a door (9), a container (8) containing said muffle, and control means (22) being external to said muffle (12) adapted to control the temperature inside the cooking compartment, characterized in that said control means (22) are located in the lower half of said container (8), preferably on the base of said container.

2. Pyrolitic oven according to claim 1, characterized in that said control means are adapted to adjust the power of a first element (15) located on the side opposite to said aperture, and of a second element (14) mounted to the top of said muffle.

3. Pyrolitic oven according to claim 2, characterized in that said first element (15) and said second element (14) are the only elements adapted to heat the inside of said cooking compartment.

4. Pyrolitic oven according to claim 2, characterized in that said oven comprises cooling means adapted to draw air (F) from outside said container and to make air circulate inside said container.

5. Pyrolitic oven according to claim 4, characterized in that said cooling means comprise a fan (23) being external to said muffle (12) and located in the upper half of said container (8).

6. Pyrolitic oven according to one of the previous claims, characterized in that it comprises a user interface device (27) adapted to the selection of the functions of said oven and connected to said control means (22) through electric cables, optical fibers or by radio.

7. Pyrolitic oven according to claim 6, characterized in that said user interface device (27) is inserted inside a handle (10) associated with said door (9).

8. Pyrolitic oven according to claim 7, characterized in that said user interface device (27) can be separated from said oven and used remotely.

9. Pyrolitic oven according to claim 6 or 8, characterized in that said user interface device

(27) is a remote control unit.

10. Pyrolitic oven preferably according to one of the previous claims, characterized in that said oven comprises a fan (16) being internal to said muffle (12) and mounted close to said first element (15), as well as diverting means adapted to direct the most part, preferably at least 50%, of the air flow generated by said fan towards the lower portion of said cooking compartment.

11. Pyrolitic oven according to claim 10, characterized in that said diverting means comprise a guard (28) for protecting said internal fan.

12. Pyrolitic oven according to claim 11, characterized in that said guard (28) of said internal fan (16) comprises a panel being polyhedric, preferably substantially cylindrical, in shape and mountable to or integrated with a first wall of the cooking compartment being opposite to said aperture, said panel having:

- at least a first face positioned towards said aperture, and a side surface connecting said first face to said first wall of the cooking compartment,

- a plurality of apertures (29,30) being present on said first face and along said side surface, and that at least 50% of the overall surface of the apertures (29) along the side surface of the polyhedron is contained in the polyhedron half facing the base of the cooking compartment.

13. Pyrolitic oven according to claim 12, characterized in that said apertures (29) along said side surface (30) have larger dimensions than the apertures (29) being present on said first face.

14. Pyrolitic oven according to claim 12, characterized in that at least one of said apertures

(29) along the side surface has an area of a few cm².

15. Pyrolitic oven according to one of the previous claims, characterized in that said muffle (12) has a volume of approximately 50 It and said oven (3) is adapted to be built-in in a recess (4) having at least one side measuring 48 cm.

16. Oven comprising a muffle delimiting a cooking compartment and two elements

(14,15), a first one (15) of said two elements being located on a first wall of said cooking compartment close to a fan (16) generating an air flow (C), and a second element (14) being located on a second wall of said cooking compartment, characterized in that said oven comprises diverting means adapted to divert said air flow (C) toward the wall of the cooking compartment being opposite to said second wall.

17. Oven comprising a muffle (12) delimiting a food cooking compartment, a container (8) containing said muffle (12), control means (22) adapted to control the operation of said oven, and a user interface device (17) connected to said control means (22) and adapted to select the operation of said oven, characterized in that said user interface device (27) can be separated from said oven and used remotely, and that, preferably, the width and height of said container (8) are substantially equal to the width and height of said muffle.