Direct-heating fan oven

The present invention relates to an oven comprising: a muffle that defines a cooking cavity for containing foods to be cooked, the muffle comprising at least one horizontal floor, heating means adapted to heat air, ventilating means adapted to circulate the air, at least one air distribution element comprising at least one channel adapted to receive the air being circulated and to allow it to flow through, wherein the distribution element further comprises a plurality of inlet openings in fluidic connection with the at least one channel and adapted to supply air into said cooking cavity; the ventilating means comprise at least one fan in fluidic connection with the distribution element, the fan being placed at least partially under the level of the horizontal floor.

TECHNICAL FIELD

The present invention relates to a fan oven, in particular for household use.

PRIOR ART

Fan ovens according to the prior art comprise a cooking cavity that is heated by suitable heating means, and ventilating means, such as one or more fans, associated with the heating means for circulating hot air inside the cooking cavity. The foods contained in the cooking cavity are hit by the hot air current and cooked.

In production ovens, the ventilated cooking system normally comprises a bulkhead, a fan, and a circular resistor. The bulkhead performs the task of dividing the space of the muffle into two parts, i.e. a first part where food is placed for cooking, and a second part where air is heated. The fan performs the task of giving kinetic energy to the air, which then enters the cooking cavity through slots typically arranged at the sides of the bulkhead, and is recovered through a grid, called a return grid, arranged in front of the bulkhead.

The air flowing from the bulkhead into the cooking cavity through the side slots typically has a hardly controllable chaotic motion, which also depends on the direction of rotation of the fan. In particular, the cooking of the food placed in the central region of the cavity is related to the return of the air, which in that region is normally colder and, for this reason, may cause uneven cooking and browning of the food. This type of cooking can be defined as “passive” cooking.

A further example of a fan oven according to the prior art is described in patent application EP2607797A2 by Indesit Company S.p.A., which relates to an oven of the ventilated type that comprises: a muffle that defines a cooking cavity, heating means associated with the muffle for heating the air, a fan for circulating air inside the muffle, positioned in an interspace of the back wall of the muffle, behind a bulkhead. The fan oven known from patent application EP2607797A2 envisages that the fan interspace is in fluidic connection with the muffle compartment for supplying hot air into the muffle itself, and that there are return means allowing the air in the muffle to be sucked by the fan into the interspace and heated again. The solution known from patent application EP2607797A2 envisages the presence of a channel proximal to the front wall of the muffle, through which air it taken from the muffle.

Fan ovens in known configurations like the one exemplified above still suffer, however, from a few drawbacks.

In particular, the temperature distribution inside the muffle is not sufficiently even, and is adversely affected by the fluid dynamics imposed by the oven, which condition the hot air flow coming from the heating element.

Therefore, the efficiency of the fan ovens known in the art is not adequate for the food cooking process that must take place inside said cooking cavity.

This problem is particularly felt when multiple foods must be cooked simultaneously in the cooking cavity on different trays arranged at different levels. It has been observed that, when several shelves or pans are placed at different levels in the cooking cavity, the foods contained therein get cooked differently.

Furthermore, such dishomogeneousness of the air distribution in the cooking cavity is also observed, to some extent, at each level of the cooking cavity, since foods get cooked differently even when they are put on the same shelf.

It is clear that this inevitably poses significant difficulties to the user, who will find it impossible to attain a homogeneous cooking of foods placed in the cooking cavity.

Furthermore, the generic configurations envisaged by the prior art share the fact that they do not take appropriately into account the fluid dynamics existing in the cooking cavity, leading to the risk of problems arising during the use of the fan oven.

OBJECTS AND SUMMARY OF THE INVENTION

It is one object of the present invention to provide a fan oven capable of solving some of the problems suffered by the prior art.

In particular, it is one object of the present invention to provide a fan oven which is so designed as to ensure that the hot air flow will be distributed evenly inside the cooking cavity.

It is another object of the present invention to provide a fan oven which is so designed as to ensure an effective circulation of the air flow between the heating elements and inside the cooking cavity.

It is a further object of the present invention to provide a fan oven which is so designed as to ensure a better cooking of the foods, even when the latter are simultaneously placed in the cooking cavity at different levels.

It is a further object of the present invention to provide a fan oven that optimizes the fluid dynamics in the cooking cavity.

It is a further object of the present invention to provide a fan oven that optimizes the fluid dynamics in the air circulation ducts, under the action of the ventilating means.

These and other objects are achieved through a fan oven as set out in the appended claims, which are an integral part of the present description.

A basic idea of the present invention is to provide an oven comprising: a muffle that defines a coking cavity for containing foods to be cooked, the muffle comprising at least one horizontal floor, heating means adapted to heat air, ventilating means adapted to circulate the air, at least one air distribution element comprising at least one channel adapted to receive the air being circulated and to allow it to flow through, wherein the distribution element further comprises a plurality of inlet openings in fluidic connection with the at least one channel and adapted to supply air into the cooking cavity; the ventilating means comprise at least one fan in fluidic connection with the distribution element, the fan being placed at least partially under the level of the horizontal floor.

This solution improves the air circulation through the heating elements and inside the cooking cavity.

This solution also optimizes the fluid dynamics in the air circulation duct, under the action of the ventilating means.

Thus, the invention envisages to modify the air heating and circulation system in order to attain an “active” type of cooking.

Further advantageous and particular aspects will become apparent from the following detailed description and from the dependent claims.

The drawings show different aspects and embodiments of the present invention and, where appropriate, similar structures, components, materials and/or elements are designated in the various drawings by the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows an exploded view of an oven1comprising a muffle2that defines a cooking cavity3for containing foods to be cooked, which are typically placed on pans4, or shelves and trays, that can be inserted into the cooking cavity3.

The muffle2comprises at least one vertical back wall5and heating means6adapted to heat air; the heating means6are enclosed in a tray7positioned underneath the cooking cavity3, separated from the latter by a dividing floor8.

The oven1further comprises ventilating means, such as at least one fan9, adapted to circulate the air inside the oven1. The fan9is thus in fluidic connection with the distribution element5, and is positioned under the level of the horizontal floor8. Therefore, the tray7is in fluidic connection with the fan9. A space, i.e. the tray7, is thus dedicated to housing a heating element6in the base of the muffle2, and a dividing floor8confines the space dedicated to the heating element6and provides return slots or openings12through which the air is recovered after having yielded its heat to the foods being cooked.

More in particular, the fan9comprises an impeller in fluidic connection with the region underneath the horizontal floor8on the upstream side relative to the direction of circulation of the heated air. At the same time, on the downstream side relative to the direction of circulation of the heated air, the impeller of the fan9is in fluidic connection with the distribution element5.

According to a preferred embodiment, the impeller of the fan9is of the centrifugal type, with an axial inlet for said heated air, and a radial outlet for said heated air.

Further embodiments may envisage the presence of one or more fans, even of different types, e.g. tangential fans, axial-centrifugal fans, etc., which may alternatively be used with the same hot air intake and distribution system described herein.

Due to the presence of the heating element6in the tray7, energy is saved because the main heating element6is located under the bottom of the cooking cavity3; therefore, in addition to heating air for convective cooking, it also participates in heating the floor8, which thus becomes an active hot surface without requiring an additional heating element dedicated thereto.

The oven1then comprises at least one air distribution element10associated with the vertical back wall5and comprising at least one channel10(or10aand10b) adapted to receive the heated air circulated by the fan9and to allow it to flow through.

The distribution element5comprises a plurality of inlet openings11, which are in fluidic connection with the channel10and are adapted to supply the heated air into the cooking cavity3.

The inlet openings11are positioned, preferably in pairs, at different levels on the distribution element5; preferably, each opening of a pair is located on one of the different channels10aand10b.

The channel10preferably comprises a confining element13adapted to reduce the cross section available for the heated air as it flows through the space between two inlet openings located at different levels on the distribution element5.

This provides a reduction of the cross section as the air covers the path within the distribution element5, resulting in a balanced air flow between the air inlets that are closer to the fan9and those that are farther from the fan9, whether at the same level or, most importantly, at different levels. In this way it is possible, among other things, to optimize and even out the cooking of the foods.

Preferably, the fan9is of the centrifugal type and is positioned underneath the distribution element5. Preferably, the fan9comprises, therefore, a centrifugal impeller and an associated scroll that increases the efficiency of the impeller, the task of which is to suck air from the slots12of the floor8through the heating element6and direct it towards the distribution element5.

The hot air distribution element5then comprises a bulkhead10with front slots or inlet openings11, which exploit the Coanda effect. For this purpose, each one of the inlet openings11further comprises a deflecting element (not visible in the drawing) internal to the channel10, and further comprises a surface (not shown) adapted to cooperate with an inner wall of the channel10, so shaped as to allow the heated air flow to be deflected into the cooking cavity3. Preferably, said shape of the internal deflecting element and of the surface is obtained by drawing the inlet openings11. As aforesaid, the inlet openings11are located at different levels to serve the cooking shelves4in a more uniform manner.

The air that has exchanged heat by convection with the foods is preferably recovered in the front part of the cavity3, where slots12are provided on the floor8. The centrifugal fan9downstream of the slots12sucks this air, causing it to flow through the heating element6for heating it again.

As better shown inFIG. 2, the oven1preferably comprises a first channel10aand a second channel10b. Each one of the channels10aand10bcomprises respective inlet openings11as already described. The reduction of the available cross section is obtained by means of a confining element13interposed between the first channel10aand the second channel10b; the confining element13defines a volume that preferably has a triangular section in projection on the vertical back wall, as shown in part (a) ofFIG. 2.

The oven1then comprises support means14for at least one pan4inside the cooking cavity3, as shown in the sectional view of part (b) ofFIG. 2. The support means14are positioned at a plurality of heights compatible with the different levels of the inlet openings11, so that there is at least one inlet opening11higher than said pan4positioned at any level defined by the support means14. The openings11are thus configured for ensuring that the various shelves4will be hit by a heated air current, such that the cooking will be more uniform on each shelf4and also among the various shelves4. In particular, the hot air circulation is represented in part (b) ofFIG. 2by straight arrows indicating the direction of circulation of the flow.

In one embodiment, the oven1further comprises sensing means, such as switches, adapted to detect the presence of at least one pan4(wherein said pan4is suitably configured as a partition, and hence is called “divider”) at a specific level defined by the support means14. In such an embodiment, the oven1further comprises means adapted to change the opening configuration of at least one of the inlet openings11. Such means may comprise movable deflectors or baffles that may be operated mechanically or by electric actuators or motors, by means of which the heated air can be selectively made to exit through specific inlet openings11. In this manner, it is possible to exploit the insertion of a “divider” such as the pan4for partitioning the cooking cavity3and obtaining a more effective heating without wasting energy, thereby improving the energetic efficiency of the oven1.

In an alternative embodiment, the oven1comprises means adapted to modify the opening configuration of at least one of the inlet openings11based on suitable commands issued by a control unit, whether automatically or upon a selection made by the user.

The distribution system, if designed for this purpose, can thus be used for obtaining differentiated cooking results by directing more air towards specific levels. This offers the possibility of cooking, during the same cycle, foods requiring, within a certain extent, different cooking times. The system thus implemented, in addition to offering clear cooking advantages, is also advantageous in terms of energetic efficiency. The air flow is no longer delivered into a large cavity, where it would exchange heat with side surfaces of the muffle2not used for heating foods; this will be reflected in less energy needed for cooking foods.

In general, it is possible to achieve cooking efficiency even without necessarily employing means adapted to vary the configuration of the inlet openings11; to this end, it becomes important to properly size the inlet openings11so as to obtain optimal cooking results on each shelf considered individually (in this case, the above-described cooking flexibility among the various shelves would however be lost).

FIG. 3illustrates a variant of the oven1, comprising a different configuration6bof the heating means6ofFIG. 1. This variant will be described more in detail with reference toFIGS. 5 and 6.

FIG. 4illustrates an embodiment of the oven1, comprising a further air circulation element41, i.e. a fan located on the top surface of the cooking cavity3, which allows direct fluidic connection between the cooking cavity3and an air channel arranged above the muffle2; such elements allow the cooking fumes to be extracted from the cooking cavity3, thereby ensuring an optimal humidity level for cooking the food.

The oven1ofFIG. 4comprises further heating means42, which will be described more in detail below, positioned at the entrance of the channel10and downstream of the fan9, which can be used for pyrolyzing smells transported by the heated air flow, preferably operating by incandescence at temperatures in excess of 400-500° C., or as an additional element for heating the air to be supplied into the cooking cavity3.

With reference toFIGS. 5 and 6, there are shown two embodiments6aand6bof the heating means in the oven1, wherein the presence of at least one tubular electric resistor6ais envisaged.

The tubular electric resistor6acomprises a spiral element wound around it (not shown) and adapted to increase the thermal exchange with the heated air coming from the cooking cavity3, which has already exchanged heat with the foods being cooked. In this embodiment, the tubular electric resistor6ahas the peculiarity of being formed by a hot pipe (resistor) on which a spiral is applied, forming a continuous fin that increases the exchange area and hence improves the efficiency of the system.

The tubular electric resistor6b, instead, comprises a plurality of substantially parallel fins61adapted to enhance the thermal exchange with said heated air. This version of the tubular electric resistor6bproves to be more efficient, and comprises a hot coil (resistor), wherein the pipes are arranged in an alternated fashion, with a series of fins61arranged parallel to the air flow, thus forming a heating battery.

In yet another variant (not shown), the fins61are replaced by a foil arranged between the two rows of pipes, the surface of which lies in the same plane as the air flow; this variant provides a more economical alternative to the finned variant of the tubular electric resistor6b.

A further variant (not shown) comprises a hot battery, wherein the pipe element and the fins61are replaced by an incandescent wire element with a foil positioned between the filaments, the surfaces of which lie in the same plane as the air flow.

With reference toFIG. 7, there is shown a preferred embodiment of the additional heating means42ofFIG. 4, consisting of a filament heater comprising a plurality of electrically heated filaments71arranged transversally to the air flow that crosses the additional heating means42. As already described, the plurality of heated filaments71are preferably adapted to pyrolyze smells transported by the air flow, since they operate by incandescence, and/or are adapted to additionally heat the air to be supplied into the cooking cavity3.

In another embodiment of the oven1according to the present invention, in addition or as an alternative to the embodiments described so far with reference toFIGS. 1 to 7, it is envisaged to provide one or more inlet openings11with at least one grease filter, which reduces the fouling of the oven in general, reducing in particular the fouling of the functional elements thereof (such as the resistors and the fan), thus contributing to keeping the latter efficient by preventing deposits of cooking residues transported by the air that flows through said elements. Said grease filter may comprise, for example, metallic mesh elements that can be washed and reconditioned.

In yet another embodiment of the oven1according to the present invention, in addition or as an alternative to the embodiments described so far with reference toFIGS. 1 to 7, it is envisaged to provide the oven1with a floor8made of glass-ceramic, which is transparent to heat and allows the heating element6to be used as a radiating element, thus creating a “fast-oven” food cooking configuration.

In yet another embodiment of the oven1according to the present invention, in addition or as an alternative to the embodiments described so far with reference toFIGS. 1 to 7, it is envisaged to provide the oven1with a lower heater of the “thick-film” type, preferably applied to the floor8, e.g. on a glassy, ceramic or metallic support, as an alternative to the above-mentioned heaters.

In the light of the above description of some preferred and advantageous embodiments of the present invention, it will be apparent to one skilled in the art that the invention may be subject to further modifications and variations.

For example, the centrifugal fan described herein may be manufactured as a single part, wherein the scroll and the air distribution element are made as one piece, as opposed to two separate pieces.

The inlet openings11may be in a different number than described herein, and may also have different shapes from one another.