EP2103878A1

EP2103878A1 - Cooking oven with humidification device

Info

Publication number: EP2103878A1
Application number: EP08425183A
Authority: EP
Inventors: Silvano Fumagalli
Original assignee: Candy SpA
Current assignee: Candy SpA
Priority date: 2008-03-20
Filing date: 2008-03-20
Publication date: 2009-09-23
Anticipated expiration: 2028-03-20
Also published as: EP2103878B1; ES2542149T3

Abstract

A cooking oven (1), particularly of the household electrical type, comprises a housing (2) with a cooking recess (3); heating means (4); and a humidification device (10) adapted to inject moisture into the cooking recess (3), wherein the humidification device (10) comprises water amount supplying means (11, 12), and a piezoelectric aerosol generator (13).

Description

The present invention relates to a cooking oven, particularly a household electric oven, provided with a humidification device.
Household electric ovens usually comprise a housing with a cooking recess defining therein a cooking space to receive the dishes to be cooked. The cooking recess is surrounded by a layer of thermoinsulating material, and has an access opening which can be closed by means of a door which is hinged to the housing forming the household appliance outer covering.
In order to carry out the heating of the cooking space, the cooking recess is provided, at the lower and upper walls thereof, with heating members typically composed by armoured tube resistors. The lower heating member is typically arranged outside the cooking space, between the cooking recess lower wall and the thermoinsulating layer, so as to heat the dishes, particularly those in the cooking space lower part, through such lower wall. Instead, the upper heating member is typically composed of a resistor which is coil-shaped and arranged inside the cooking space, adjacent the cooking recess upper wall, so as to heat the dishes, particularly those in the cooking space upper part, by convection and thermal irradiation.
In order to achieve a preferably even heating distribution, particularly of the hot air inside the cooking recess, the electric cooking ovens comprise an air ventilation and circulation system. Typically, such air circulation system provides a fan wheel actuated by a electric motor, and in flow communication with the cooking recess, so as to be able to generate a circulation of the air in the cooking space. Furthermore, it is known to arrange one or more further heating members, for example, resistors, in the path of the air flow generated by the fan wheel, so as to heat the air circulating downstream the cooking recess, and before the air laps against the dishes arranged in the cooking space.
Cooking ovens having a humidification function for the cooking environment further comprise a humidification device which injects moisture into the cooking recess. This allows an improved preservation of the foods organolectic properties, and a reduced weight loss due to fluid leakages, which is an important aspect while cooking meats, which keep their own juices therein, thus remaining soft and tasty.
When cooking vegetables, the cooking recess humidification obviates an undue drying, with relative loss of vitamins and mineral salts. A further known advantage of the cooking ovens having a humidification function is that, during the cooking of breads and derivates, the moisture ensures elasticity and softness also to the outer layer of the dough, thus avoiding crust tearing during a volume increase.
In the cooking ovens of the prior art, particularly of the industrial type, the cooking recess humidification is achieved by boilers which develop vapour, or by water atomization pneumatic devices. Such known systems, while being satisfactory as regards humidification, are expensive and technically complex. Furthermore, the vapour generators consume a considerable amount of electrical power, on the order of hundreds of Watts, and require special anti-explosion safety measures for the boiler.
This also translates in high overall dimensions, which compromise the application of these humidifiers in household electric ovens, particularly those of the built-in type.
Therefore, object of the present invention is to propose a cooking oven with humidification device, particularly of the household electrical type, having such features as to obviate at least some of the drawbacks cited with reference to the prior art.
Within the scope of the main object, a further object of the present invention is to propose a cooking oven with humidification device which has a simplified structure, does not require anti-deflagration safety measures, and has reduced power consumes.
Such object is achieved by a cooking oven, particularly of the household electrical type, comprising a supporting and housing structure with a cooking recess adapted to receive the dishes; heating means arranged in a thermal exchange relationship with the cooking recess; and a humidification device adapted to inject moisture into the cooking recess,
in which said humidification device comprises:

water amount supplying means;
water atomization means;

characterized in that

The piezoelectric aerosol generator in contact with the water to be converted into moisture expands and shrinks in response to a potential difference applied to the piezoelectric crystal, thus applying a high frequency vibration (in the ultrasound range) to the water, such as to generate an instantaneous, cold aerosol flow.
In order to better understand the invention, and appreciate the advantages thereof, the exemplary, nonlimiting description of some embodiments thereof will be set forth herein below.
The only Figure schematically shows a cooking oven according to an embodiment of the invention.
With reference to the Figure, a cooking oven 1 comprises a housing 2, inside which a cooking recess 3 is arranged, preferably wrapped in a layer of thermoinsulating material, and intended to receive the dishes to be cooked. The cooking recess 3 is defined by an upper wall, a lower wall, a rear wall, and side walls provided with sliding guides adapted to slidingly support shelves 5 of the "grid" or "sheet" type, which can be withdrawn from the cooking recess 3 through an access opening, which can be closed by means of a door (not shown) preferably secured to the oven 1 housing 2.
The oven 1 further comprises a suction system to suck fumes and vapours from inside the cooking recess 3. The suction system comprises air inlet openings arranged in the housing 2 lower part, and air outlet openings preferably arranged in the housing upper front part. The inlet and outlet openings are mutually connected through a tubing system (not shown) inside which an air flow is created, by means of so-called "tangential" or "entrainment" ventilating means 6. Such entrainment flow creates a suction inside a jointing tube connected to the tubing opening with one attachment end thereof to the cooking recess.
The oven 1 is provided with heating means, for example, resistors 4 or, in the case of gas ovens, with burner units which are arranged outside and/or inside the cooking recess 3.
In accordance with an embodiment, a lower heating member is arranged outside the cooking space between the cooking recess 3 lower wall and the thermoinsulating layer, so as to heat the dishes, particularly those in the cooking space 3 lower part, through such lower wall. A further upper heating member, consisting in a coil-shaped resistor, is arranged inside the cooking recess 3, adjacent the upper wall thereof, so as to heat the dishes, particularly those in the cooking recess upper part, by convection and thermal irradiation. Alternatively to the coil-shaped resistor, the upper heating member comprises an infrared and/or thermal irradiation plate secured to the cooking recess 3 upper wall.
In at least one of the cooking recess 3 walls, or between one or more of these walls and the thermoinsulating material layer, a ventilation space is obtained, which is provided in flow communication with the cooking recess 3 through one or more suctioning openings and one or more ventilation openings obtained in at least one of the walls defining and separating cooking recess 3 and ventilation space one from the other. In the ventilation space, a recirculating fan wheel 7 is arranged, which can be actuated by an electric motor and which is intended to mix the air inside the cooking recess 3. To this aim, the recirculating fan wheel 7 is adapted to suck air from the cooking recess 3 through the suctioning openings in the ventilation space, and to input air from the ventilation space back into the cooking recess 3 through the ventilation openings. In this manner, the recirculating fan wheel 7 generates an air flow in the cooking recess 3 which extends from the ventilation openings through regions in which the air laps against the dishes arranged in the oven up to the suctioning openings.
In order to heat the air flow during the recirculation, one or more further heating members (not shown) can be provided, for example, resistors arranged in the path of the air flow generated by the recirculating fan wheel 7.
The cooking oven 1 further comprises a humidification device 10 with water amount supplying means which is sufficient to the generation of moisture, for example, a water reservoir 11 arranged outside the cooking recess 3 but inside the housing 1 or, alternatively, a water duct connectable to a water source outside the oven.
In accordance with an embodiment, the water reservoir 11 is arranged between an outer wall of the housing 2 and the cooking recess 3 rear wall, or between an outer wall of the housing 2 and one of the cooking recess 3 side walls, and extends in the vertical direction at least along a major part of the cooking recess 3 full height.
The water reservoir 11 can be removably housed in a seat which is accessible by the user, in order to allow the filling thereof, or a filling opening can be provided which is accessible from outside the oven, and which is in flow connection with the same reservoir 11.
In order to allow the detection of the reservoir 11 filling status from outside the oven, a level indicator 20 can be provided, preferably arranged on the oven front side, in the proximity of the handles 9 for the cooking program setting and selection. Such level indicator 20 can be operatively connected to a float in the reservoir 11, with discrete level sensors in the reservoir, or it can comprise an indicator tube communicating with the reservoir 11 so that the water level in the indicator tube is identical to the water level in the reservoir.
The humidification device 10 further comprises an atomization tank 12 adapted to contain a water portion in contact with a piezoelectric aerosol generator 13, which will be described herein below. The atomization tank 12 can be configured as a portion of the water reservoir 11 and directly connected thereto, or it can be manufactured as a single piece therewith. Alternatively, the atomization tank 12 is configured as a container separated from the reservoir 11 and supplied therefrom through a feeding opening 25. The feeding opening 25 is preferably obtained in the reservoir 11 lowermost point, so that the water is conveyed to the atomization tank by the force of gravity.
Alternatively, the reservoir 11 can be connected to the atomization tank 12 through a capillary tube duct or a suction duct, so that the liquid which the reservoir 11 holds can be conveyed into the atomization tank 12 through a suction induced by a pressure differential between reservoir 11 and atomization tank 12, and under the capillary action in the same tube.
In accordance with an embodiment, valve means 26 are provided which are adapted to control the water passage through the feeding opening as a function of the water level in the atomization tank and, particularly, as a function of the water level relative to the piezoelectric aerosol generator 13.
The valve means 26 may comprise a float valve, or a valve which, during the closure thereof, is stressed by an elastic preload, such as to ensure a closure of the feeding opening 25 whenever a preset upper water level suitable to a piezoelectric aerosol generator 13 proper functioning is achieved or exceeded in the atomization tank and, similarly, an opening of the feeding opening 25 whenever the water in the atomization tank reaches or falls below a preset lower water level suitable to the piezoelectric aerosol generator 13 proper functioning.
According to the space requirement in the oven 1 housing 2, the atomization tank 12 can be arranged beneath the cooking recess 3 or laterally relative to the cooking recess 3. As already described with reference to the reservoir 11, the atomization tank 12 can also be configured as a fitting which can be withdrawn from and inserted into a special seat obtained in the housing 2, or as a fixed component of the oven. In order to allow the atomization tank 12 emptying, a waste pipe 21 can be provided which can be closed by means of a plug 22 and which is configured to allow the discharge of the water outside the oven.
The piezoelectric aerosol generator 13 is so arranged and configured as to be able to transmit its own oscillatory strains as mechanical impulses to the water inside the atomization tank 12.
The transmission of the mechanical impulses preferably occurs through the direct contact (e.g., by dipping) of a vibrating plate 15, made of or connected to a piezoelectric crystal 14, with water.
Alternatively, such transmission of the vibrating plate 15 oscillation to the water can occur in an indirect manner, through a solid transmission means (a mechanical stirrer), or through a transmission fluid (an hydraulic or pneumatic stirrer).
In accordance with an embodiment, the aerosol generator 13 vibrating plate 15 is arranged just beneath and essentially parallel to the water level in the atomization tank 12. The term "water level" means herein the preset water level range suitable to the aerosol generator functioning.
The piezoelectric aerosol generator 13 is electrically connected to a control circuit board 16 so configured as to energize the piezoelectric crystal or crystals 14 as a function of a preset cooking program or selected type of dish by means of the handles 9 or other member for the user interfacing. To this aim, the control circuit 16 is connected to an electronic control unit 8, or integrated therein.
Therefore, the control unit 8 is configured to drive the supply of heating resistors, ventilation system, and humidification device as a function of the cooking parameters which the user can choose from.
Advantageously, a moisture sensor 23 is further provided which is arranged in the cooking recess 3, or in communication with the internal environment of the cooking recess 3, and in signal connection with the control unit 8, that is with the electronic circuit board 16 driving the supply of the piezoelectric aerosol generator 13. In this manner, the control unit 8 drives heating, ventilation, and humidification of the dishes as a function of the cooking program which is selected by the user, and the moisture and effective temperature which are detected by the sensors.
The temperature sensor, while being per se well-known, is indicated for the sake of completeness with the numeral reference 29.
In order to convey the aerosol flow 27 from the atomization tank 12 into the cooking recess 3, an aerosol duct 17 is provided which is connected to the tank 12 above the water upper level, and to the cooking recess 3, preferably but not necessarily, at one of the side walls about at the cooking recess 3 half height.
According to an embodiment, aerosol distribution means are provided inside the cooking recess, for example, a distribution barrier 18 arranged inside the cooking recess 3 facing the aerosol duct 17 outlet 28. The distribution barrier 18 is preferably configured as a wall with a plurality of passage openings 19 in order to promote the greatest moisture distribution possible. The aerosol which is so spread while inputting it into the cooking recess 3, immediately vaporizes thanks to the heat present in the oven, and evenly distributes in all the regions of the cooking recess 3.
In accordance with a further embodiment, the humidification device 10, comprising reservoir 11, atomization tank 12, piezoelectric aerosol generator 13 and, preferably, aerosol generator control unit 16 is configured as a pre-assembled assembly which can be mounted in the oven housing.
The cooking oven according to the present invention has a number of advantages. It allows a structure simplification, a reduction of overall dimensions and power consumes for the humidification function, it obviates the dangerousness of the pressurized vapour which is reported for the known ovens with boiler, and it allows for the instantaneous production of moisture.
Last, but not least, thanks to the possibility to select the cooking parameters:

temperature;
ventilation;
moisture;
as a function of:
selected cooking program;
measured effective moisture;

It shall be apparent that, to the cooking oven according to the present invention, one of ordinary skill in the art, with the aim of meeting contingent, specific, needs, will be able to make further modifications and variations, all of which anyhow fall in the protection scope of the invention, as defined by the following claims.

Claims

A cooking oven (1), particularly of the household electrical type, comprising a supporting and housing structure (2) with a cooking recess (3) adapted to receive the dishes; heating means (4) arranged in thermal exchange relationship with the cooking recess (3); and a humidification device (10) adapted to inject moisture into the cooking recess (3),
wherein said humidification device (10) comprises water amount supplying means (11, 12) and water nebulization means,
characterized in that said nebulization means comprise a piezoelectric aerosol generator (13).
The cooking oven (1) according to claim 1, wherein said water supplying means comprise a water reservoir (11) arranged between an outer wall of the housing (2) and the cooking recess (3), and extended in the vertical direction at least along a major part of the cooking recess (3) full height.
The cooking oven (1) according to claim 2, wherein the water reservoir (11) is removably housed in a seat accessible by the user in order to allow the filling thereof.
The cooking oven (1) according to claim 2, comprising a filling opening accessible from outside the oven, and in flow connection with the same reservoir (11).
The cooking oven (1) according to one of the claims 2 to 4, comprising a level indicator (20) operatively connected to the reservoir (11).
The cooking oven (1) according to claim 5, wherein said level indicator comprises an indicator tube (20) communicating with the reservoir (11) so that the water level in the indicator tube is identical to the water level in the reservoir (11).
The cooking oven (1) according to any preceding claim, wherein the water supplying means comprise an atomization tank (12) supplied with water by said reservoir (11), and adapted to contain a water portion in contact with said piezoelectric aerosol generator (13).
The cooking oven (1) according to claim 7, wherein said atomization tank (12) is configured as a portion of the water reservoir (11) and is manufactured as a single piece therewith.
The cooking oven (1) according to claim 7, wherein said atomization tank (12) is configured as a container separated from the reservoir (11) and supplied therefrom through a feeding opening (25).
The cooking oven (1) according to claim 9, wherein the feeding opening (25) is obtained in the reservoir (11) lowermost point, so that the water is conveyed to the atomization tank due to the force of gravity.
The cooking oven (1) according to claim 7, wherein the reservoir (11) is connected to the atomization tank (12) through a capillary tube duct or a suction duct, so that the liquid which is hold in the reservoir (11) can be conveyed to the atomization tank (12) by a suction caused by a pressure differential between reservoir (11) and atomization tank (12), or under the capillary action in the same tube.
The cooking oven (1) according to claim 9,comprising valve means (26) adapted to control the water passage through the feeding opening (25) as a function of a water level in the atomization tank (12), and as a function of a water level relative to the piezoelectric aerosol generator (13).
The cooking oven (1) according to claim 12, wherein the valve means (26) are selected from the group consisting of:
- a float valve;

- a valve which is elastically biased in a closed configuration,
so as to close the feeding opening (25) whenever a preset water upper level suitable to a proper functioning of the piezoelectric aerosol generator (13) is exceeded in the atomization tank, and so as to open the feeding opening (25) whenever the water in the atomization tank falls below a preset water lower level suitable to the proper functioning of the piezoelectric aerosol generator (13).
The cooking oven (1) according to any one of the claims 7 to 13, wherein the atomization tank (12) is arranged beneath the cooking recess (3), or laterally relative to the cooking recess (3).
The cooking oven (1) according to any one of the claims 7 to 14, wherein said atomization tank (12) is configured as a fitting which can be withdrawn from and inserted into a special seat obtained in the housing (2).
The cooking oven (1) according to any one of the claims 7 to 15, wherein the atomization tank (12) comprises a discharge pipe (21) which can be closed by a plug (22) and so configured as to allow the water discharge outside the oven.
The cooking oven (1) according to any preceding claim, wherein the piezoelectric aerosol generator (13) is so arranged and configured as to be able to transmit its own oscillatory strains as mechanical impulses to the water inside the atomization tank (12).
The cooking oven (1) according to claim 17, wherein the transmission of the mechanical impulses occurs by direct contact, preferably by dipping in the water, of a vibrating plate (15) consisting in, or connected to, a piezoelectric crystal (14).
The cooking oven (1) according to claim 17, wherein the transmission of the oscillation from piezoelectric aerosol generator (13) to the water can occur in an indirect manner, through a solid transmission means, or through a transmission fluid.
The cooking oven (1) according to claim 18,
wherein said aerosol generator (13) vibrating plate (15) is arranged just beneath and essentially parallel to the water level in the atomization tank (12).
The cooking oven (1) according to any preceding claim, wherein the piezoelectric aerosol generator (13) is electrically connected to a control circuit (16) connected to an oven (1) control unit (8), or integrated therein, and so configured as to energize the piezoelectric crystal or crystals (14) as a function of a cooking program which can be preset by a user interface (9).
The cooking oven (1) according to claim 21, comprising a moisture sensor (23) in communication with the cooking recess (3) inner environment, and in signal connection with the control unit (8).
The cooking oven (1) according to claim 21, wherein said control unit (8) is configured to drive the supply of heating resistors, ventilation system, and humidification device as a function of the cooking parameters from which the user can select.
The cooking oven (1) according to claim 22, wherein said control unit (8) is configured to drive heating, ventilation, and humidification of the dishes as a function of the cooking program selected by the user, and of the effective moisture detected by said sensor (23).
The cooking oven (1) according to any preceding claim, comprising an aerosol duct (17) connected to said tank (12) above the water upper level and to the cooking recess (3), preferably in one of the side walls about at the cooking recess (3) half height.
The cooking oven (1) according to claim 25, comprising a distribution barrier 18 arranged inside the cooking recess 3, and facing the aerosol duct (17) outlet (28).
The cooking oven (1) according to claim 26, wherein said distribution barrier (18) is configured as a wall with a plurality of passage openings (19).
The cooking oven (1) according to any preceding claim, wherein said humidification device (10), comprising reservoir (11), atomization tank (12), piezoelectric aerosol generator (13), and preferably aerosol generator (13) control panel (16) is configured as a preassembled unit which can be mounted in the oven (1) housing (2).