EP1994827A1

EP1994827A1 - A baking oven

Info

Publication number: EP1994827A1
Application number: EP20080425193
Authority: EP
Inventors: Tiziano Lacche'
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2007-05-25
Filing date: 2008-03-25
Publication date: 2008-11-26
Also published as: RU2008111051A; RU2471124C2

Abstract

A baking oven comprises:
- an inner compartment (2) for receiving the foods to be baked;
- means (40) for generating baking flames comprising at least a first and a second gas-fired burner (41, 42) in thermal contact with said inner compartment (2);
- at least a first support (31) which can be positioned in the inner compartment (2) and is suitable to support directly a food to be baked or is suitable to support directly a container in which the food to be baked is placed.

Let an ideal reference straight line be defined, coinciding with the physical vertical, and let a reference plane be defined, orthogonal to said ideal reference straight line and passing through at least one point of the first support (31).

The oven comprises means (30) for positioning the first support (31) in at least one operative position in which said reference plane is positioned above the first and the second burner (41, 42) and in which said first support (31) is in the inner compartment (2).

Description

The present invention relates to an oven for baking foods: said baking oven is preferably employed in a home environment.
Known baking ovens comprise an inner compartment for receiving the foods to be baked, said inner compartment being defined by:

an opening that enables to introduce and extract foods from said inner compartment, said opening being closable by a door;
a bottom surface opposite to said door at least when said door is in closed position;
a lower base and a ceiling that develop between said door and said bottom surface;
two opposite lateral surfaces that develop between said base and said ceiling.

The baking oven comprises a first gas burner operating mainly by convection. Said first burner is located at the lower base of the inner compartment, nearly abutting the bottom surface of the inner compartment. Said type of baking ovens is widely used above all in Great Britain.
Sometimes there is also a gas-fired grill operating mainly by irradiation, which can be used to provide certain foods with superficial crispness. Said grill burner is positioned at the ceiling of the inner compartment. The activation of the burner operating mainly by convection or of the grill burner operating mainly by irradiation is achieved by acting manually on a dedicated selector that enables the alternated and not simultaneous operation of the two burners.
The ovens described above have some drawbacks and/or limitations. In particular, during traditional convection baking, undesired temperature inconsistencies may be created within the baking compartment, which determine inconsistent baking. This is particularly evident if a lower shelf and an upper shelf are simultaneously present, and foods on each of the two shelves are baked at the same time. To enable the heat flow to reach also the upper shelf in said ovens, the upper and lower shelf do not completely overly the gas burner operating mainly by convection, but they leave free a rear gap that promotes heat distribution. In this way, however, since heat tends to rise upwards, the food located on the upper shelf will receive greater heat flow, which speeds up its baking. If the same type of foods is being baked both in the lower shelf and in the upper shelf, then the foods placed on the upper shelf will be completely baked before the ones placed on the lower shelf. To overcome this problem, when baking is nearly completed, there is a widespread practice of moving the foods placed in the upper shelf to the lower shelf and vice versa.
An object of the present invention is to overcome the aforesaid drawbacks, making available a baking oven that enables to obtain a homogenous and uniform baking.
These objects and others besides, which shall become more readily apparent in the description that follows, are achieved, in accordance with the present invention, by an oven having structural and functional characteristics in accordance with the appended independent claims, additional embodiments of said oven being identified in the appended and corresponding dependent claims.
The invention is described in greater detail hereafter with the aid of the drawings, which represent an embodiment provided purely by way of non limiting example.

Figures 1 and 2 show a schematic perspective views of an oven according to the present invention.
Figure 3 shows a schematic lateral section view of an oven according to the present invention.

With reference to the accompanying figures, the reference number 1 designates an oven for baking foods according to the present invention.
Said oven for baking foods is preferably used for household applications and it comprises an inner compartment 2 for housing the foods to be baked. In technical terms, said inner compartment 2 is commonly called "muffle".
The inner compartment 2 is at least in part identified by an opening 230 that enables to introduce and extract foods from said inner compartment 2, said opening 230 being closable by a door 23. The inner compartment 2 is at least in part identified by a bottom surface 24 opposite to said door 23 at least when the latter is in closed position.
The inner compartment 2 is at least in part defined by a lower base 22 and by a ceiling 21. The lower base 22 and the ceiling 21 are mutually opposite. The lower base 22 and the ceiling 21 develop between said door 23 and said bottom surface 24. Preferably, the lower base 22 and the ceiling 21 develop substantially in a respective horizontal plane.
The inner compartment 2, moreover, is at least partly defined by two opposite lateral surfaces 25, 26, preferably with substantially vertical development, which develop between said base 22 and said ceiling 21.
The baking oven 1 further comprise means 40 for generating baking flames. Said means 40 for generating baking flames comprise at least a first and a second gas-fired burner 41, 42 in thermal contact with said inner compartment 2. Said means 40 for generating baking flames enable to bake the foods. The first and the second gas-fired burner 41, 42 are of the non-grill type. The first and the second gas-fired burner 41, 42 exert their baking action on the foods operating mainly by convection.
The first and the second burner 41, 42 can operate simultaneously. Advantageously, the first and the second burner 41, 42 can be activated independently from each other. The first and the second burner 41, 42 comprise one or more slits wherefrom baking flames develop.
The oven 1 comprises at least a first support 31 which can be positioned in the inner compartment 2. The first support 31 is suitable to support directly a food to be baked or is suitable to support directly a container in which the food to be baked is placed.
The first support 31 comprises, or coincides with, a first shelf 310 or a roasting jack 311. The first shelf 310 may advantageously be a pan defining a continuous support plane without holes; alternatively, the first shelf 310 can be a grille; if the first shelf 310 is a pan, it can also support the foods directly; if the first shelf 310 is a grille, it supports a container which in turn contains the foods.
The oven 1 further comprises a second support 32 that can be positioned in the inner compartment 2 and that is suitable to support directly a food to be cooked or that is suitable to support directly a container in which the food to be cooked is placed; said second support 32 comprises, or coincides with, a second shelf 320. The second support 32 overlies the first support 31. The first and the second support 31, 32 and in particular the first and the second shelf 310, 320 can be inserted into and extracted from the inner compartment 2.
Let an ideal reference straight line be defined, coinciding with the physical vertical; let a reference plane also be defined, orthogonal to said ideal reference straight line and passing through at least one point of the first support 31.
The oven comprises means 30 for positioning the first support 31 in at least one operative position in which said reference plane is positioned above the first and the second burner 41, 42 and in which said first support 31 is internal to the inner compartment 2. Advantageously, the reference plane orthogonal to said ideal reference straight line passes through the point of said first support 31 that is closest to the lower base 22.
The positioning means 30 enable the first support 31 to assume a plurality of distinct operative positions in the inner compartment 2; as the operative position of the first support 31 changes, the location of the first support 31 also changes along the direction of development of the ideal reference straight line; in each of the operative positions allowed by the positioning means 30, said reference plane is above said first and second gas-fired burner 41, 42. Since heat tends to rise upwards, it is important that both the first and the second burner 41, 42 are positioned lower (with respect to the physical vertical) than the first and/or the second support 31, 32.
The positioning means 30 may comprise substantially horizontal guides 301 that support the first shelf 310. The same guides normally can support also the second shelf 320. The guides 301 are usually provided on the lateral walls 25, 26 that delimit at least in part the inner compartment 2. Supporting the first or the second shelf 310, 320 advantageously requires the combined action of two guides 301, each provided on one of the two opposite lateral surfaces 25, 26. The guides 301 obtained on the same lateral surface 25, 26 are positioned in the inner compartment 2 at a different distance from the lower base 22. The positioning means 30 can also comprise a support 302 of the roasting jack 311.
Said support 302 of the roasting jack 311 usually enables to place the roasting jack 311 in horizontal position (see figure 3, where a dashed line schematically indicates the roasting jack 311).
The means 40 for generating flames comprise a gas-fired grill burner 43. The gas-fired grill burner 43 is normally positioned at the ceiling 21. The gas-fired grill burner 43 operates mainly by irradiation. The gas-fired grill burner 43 can advantageously be used for baking with the roasting jack 311.
The oven 1 comprises a user interface 51 for selecting a desired baking program according to the type of food to be baked (e.g. pizza, pasta, fish, etc.). The user interface 51 enables to select the baking program also according to the type of foods to be baked simultaneously in the inner compartment 2. In this latter case, advantageously foods to be baked are placed both on the first and on the second support 31, 32, in particular both on the first and on the second shelf 310, 320. According to the selected baking program (and hence to the foods to be baked) the operating manual of the oven 1 specifies at what distance from the lower base 22 it is best to place the first and/or the second shelf 310, 320; the distance from the lower base 22 can be specified indicating in which guides 301 the first and/or the second shelf 310, 320 are to be positioned.
Advantageously the user interface 51 comprises means 510 for signalling information to the user. The signalling means 510 indicate at what distance from the lower base 22 it is best to place the first and/or the second shelf 310, 320 according to the selected baking program. This can take place by signalling on which guides 301 the first and/or the second shelf 310, 320 are to be placed. Said signalling means 510 comprise for example a display or a voice reproduction device.
The guides 301 comprise a presence sensor (which can advantageously be a weight sensor) that detects whether the first and/or the second shelf 310, 320 are positioned on the guide 301 indicated by the signalling means 510. If the user places the first and/or the second shelf 310, 320 on a different guide from the one previously signalled by the signalling means 510, then the signalling means 510 will notify the user of the positioning error of the first and/or of the second shelf 310, 320.
The oven 1 further comprises an electronic unit 53 for controlling at least a part of said flame generating means 40, said electronic control unit 53 operating according to the baking program selected through the user interface 51.
According to the baking program selected through the user interface 51, said electronic unit 53 implements a time sequence of activation/deactivation of at least the first and/or the second burner 41, 42. The time sequence is selected among a plurality of pre-determined and pre-stored time sequences, each associated with a baking program. The time sequence can be independent of thermodynamic parameters (e.g. temperature and/or humidity) measurable in the inner compartment 2 during the baking operation.
Alternatively instead the time sequence can be influenced by thermodynamic parameters (e.g. temperature and/or humidity) measured in the inner compartment 2 during the baking operation.
Advantageously the duration of at least one part of the activation and/or deactivation phases of the time sequence is equal to a predetermined value or it is determined by the reaching of a predetermined temperature in the inner compartment 2.
If the oven 1 is provided with a weight sensor, the time sequence can be influenced by the weight variation of the foods during the baking operation, measured by means of said weight sensor. The time sequence of activation/deactivation implemented by the electronic unit 53 can also provide for the regulation over time of the thermal power delivered by the first gas-fired burner 41, said thermal power of the first gas-fired burner 41 being able to assume at least two values different from zero.
The time sequence of activation/deactivation implemented by the electronic unit 53 can also provide the regulation in time of the thermal power delivered by the second gas-fired burner 42, said thermal power of the second gas-fired burner 42 being able to assume at least two values different from zero.
The time sequence of activation/deactivation implemented by the electronic unit 53 can involve, in addition to the first and/or to the second burner 41, 42, also the grill burner 43.
The time sequence of activation/deactivation implemented by the electronic unit 53 can also provide the regulation in time of the thermal power delivered by the gas-fired grill burner 43, said thermal power of the gas-fired grill burner 43 being able to assume at least two values different from zero.
The predetermined time sequence is calibrated to uniform the baking times of a first and a second food positioned simultaneously on the first and on the second support 31, 32, in particular on the first and on the second shelf 310, 320. In this case, the first and the second food can be of the same type or they can belong to predetermined types of foods.
The instructions that enable the electronic unit 53 to implement the time sequence of activation/deactivation can be stored in the baking oven during its manufacture, or they can be introduced at a later time through means for programming the oven 1 e.g. a programming keyboard (included in the user interface 51 or constituting a separate device from the user interface 51), or the oven 1 could comprise wireless or wired means for connecting to a remote database (e.g. the Internet).
The oven 1 also comprises actuator means 54 for carrying out the commands provided by the electronic control unit 53, said actuator means being operatively interposed between said electronic unit 53 and at least a part of the flame generating means 40.
The actuator means 54 advantageously comprise shut-off means 521 that can prevent the flow of gas to the first and/or to the second burner 41, 42 and/or to the grill burner 43. The shut-off means 521 comprise a first shut-off valve 522 that can prevent the flow of gas to the first burner 41. The shut-off means 521 comprise a second shut-off valve 523 that can prevent the flow of gas to the second burner 42. The shut-off means 521 comprise a third shut-off valve 529 that can prevent the flow of gas to the grill burner 43.
The actuator means 54 comprise means 55 for igniting the combustible mixture supplying at least part of the means 40 for generating baking flames (said igniting means 55 could, for example, be a device that generates sparks at the instant in which the ignition of the combustible mixture is desired). Advantageously, the means 55 for igniting the mixture are positioned in proximity both to the first and with the second burner 41, 42. The ignition means 55 are also positioned in proximity to the grill burner 43. The actuator means 54 comprise regulating means 524 that regulate the flow of gas to the first and/or to the second burner 41, 42 and/or to the gas-fired grill burner 43. In particular the regulating means 524 comprise a first regulating valve 525 positioned upstream of the first burner 41. The regulating means 524 comprise a second regulating valve 526 positioned upstream of the second burner 42. The first and the second regulating valve 525, 526 regulate the flow of gas that flows respectively to the first and to the second burner 41, 42 and hence they regulate the thermal power of the first and of the second burner 41, 42. The regulating means 524 comprise a third regulation valve that regulates the flow of the gas that flows to the grill burner 43 and hence regulates the thermal power of the grill burner 43. The first shut-off valve 522 and the first regulating valve 525 are positioned on a line 527 for supplying gas to the first burner 41. The second shut-off valve 523 and the second regulating valve 526 are positioned on a line 528 for supplying gas to the second burner 42.
The third shut-off valve 529 and the third regulating valve 530 are positioned on a line 531 for supplying the gas to the grill burner 43.
In an embodiment that is not illustrated herein, the shut-off means 521 comprise a single valve that can prevent flow both to the first and to the second burner 41, 42 and possibly also to the grill burner 43. Said valve is positioned upstream of a downstream branch-off from which originate the lines 527, 528 supplying gas to the first burner 41 and to the second burner 42, the regulating valves 525, 526 being positioned on said lines 527, 528. If supply is to be shut off also to the grill burner 43, then said single valve is positioned upstream also of a branch-off from which originates the supply line 531 that brings the gas also to the grill burner 43, the regulating valve 530 being positioned on said line 531.
When it is in one operative position, the first support 31 is interposed between the lower base 22 and the ceiling 21. Advantageously, the first support 31 is positioned at a distance other than zero from said lower base 22. In an alternative solution, the first support 31 is underneath the ceiling 21 and it can, at the limit, even coincide with the lower base 22.
Advantageously, the first and/or the second gas-fired burner 41, 42 are in proximity to the lower base 22.
The second burner 42 is positioned in proximity to said bottom surface 24.
The second burner 42 develops along a direction joining said two lateral surfaces 25, 26. The second burner 42 comprises a tubular element developing along the direction joining said two lateral surfaces 25, 26 for about 13-15 centimetres and its width is about 1 centimetre. On the upper part of the tubular element are obtained slits that, when the second burner 42 is activated, subdivide the baking flame. Relative to the physical vertical, advantageously the second burner 42 is lower than the lower base 22 or it is substantially at the same height as the lower base 22.
The first burner 41 develops between said door 23 and said second burner 42. Preferably, the first burner 41 remains at a distance of a few centimetres both from the door 23 and from the second burner 42. The first burner 41 is advantageously positioned underneath said lower base 22. In particular said first burner 41 is positioned underneath the first support 31, e.g. it is positioned underneath the first shelf 310. If the same food is to be baked simultaneously on the first and on the second shelf 310, 320, then the second burner 42 can be regulated to the maximum power and periodically the first burner 41 positioned immediately underneath the first shelf 310 will be activated to provide a heat flow destined particularly to baking the foods positioned on the first shelf 310. In this way, it is possible to prevent the foods placed on the second shelf 320 from being baked completely before the ones placed on the underlying first shelf 310, thereby obtaining a simultaneous optimal baking of the foods positioned on both shelves.
The lower base 22 has a plurality of holes 220 to enable a better distribution in the inner compartment 2 of the heat coming from the first burner 41 when said first burner 41 is positioned underneath said lower base 22. The lower base 22 further comprises a slit 221 with greater size than the holes 220. Said slit 221 enables the entry into the inner compartment of the hot air coming from the second burner 42. In a particular configuration, not illustrated, the first and the second burner 41, 42 could be side by side and develop along the direction joining the door 23 and the bottom surface 24.
The first shelf 310, when it is in said inner compartment 2, is positioned at a predetermined distance from the bottom surface 24, to promote the upward convective motion of the heat. In particular, this enables to promote the upward convective motion of the heat generated by the second burner 42 when said burner is placed at the lower base 22 in proximity to the bottom surface 24.
The oven 1 could also comprise a fan 6 that moves the air of the inner compartment 2, in such a way as to expand the baking functions which the oven can execute. In this way, it is possible to bake simultaneously on the first and on the second shelf 310, 320 foods that are even highly dissimilar from each other (in terms of type and baking time). It is possible, in this way, further to improve heat distribution in the inner compartment 2. Advantageously, the time sequence of activation and deactivation of the rotation of the fan 6 is a function of the selected baking program and it is commanded by an electronic board. Preferably, said electronic board is a part of said electronic control unit 53.
The invention achieves important advantages.
First of all, it allows a homogeneous baking of the foods, even if they are baked simultaneously on two distinct shelves.
Secondly, it allows to combine the advantages of gas baking (e.g. in terms of energy savings or baking quality) and the convenience of electronic control which manages the activation, the regulation and the deactivation of the various burners according to the foods to be baked.
The invention thus conceived can be subject to numerous changes and variants, without thereby departing from the scope of the inventive concept that characterises it.
Moreover, all details can be replaced with other, technically equivalent, elements.
In practice, all materials used, as well as the dimensions, can be any, according to requirements.

Claims

An oven for baking foods used preferably for household applications, comprising:
- an inner compartment (2) for receiving the foods to be cooked;

- means (40) for generating baking flames comprising at least a first and a second gas-fired burner (41, 42) in thermal contact with said inner compartment (2);

- at least a first support (31) which can be positioned in the inner compartment (2) and is suitable to support directly a food to be baked or is suitable to support directly a container in which the food to be baked is placed;
let an ideal reference straight line be defined, coinciding with the physical vertical, and let a reference plane be defined, orthogonal to said ideal reference straight line and passing through at least one point of the first support (31);
said oven being characterised in that it comprises means (30) for positioning the first support (31) in at least one operative position in which said reference plane is positioned above the first and the second burner (41, 42) and in which said first support (31) is in the inner compartment (2).
An oven as claimed in claim 1, characterised in that the first support (31) comprises, or coincides with, a first shelf (310) or a roasting jack (311).
An oven as claimed in claim 1 or 2, characterised in that it comprises a second support (32) which can be positioned in the inner compartment (2) and which is suitable to support directly a food to be cooked or that is suitable to support directly a container in which the food to be cooked is placed; said second support (32) comprises, or coincides with, a second shelf (320), said second support (32) overlying the first support (31).
An oven as claimed in any of the previous claims, characterised in that the positioning means (30) enable the first support (31) to assume a plurality of distinct operative positions in the inner compartment (2); as the operative position of the first support (31) varies, the position of the first support (31) also changes along the direction of development of the ideal reference straight line and in each of the operative position allowed by the positioning means (30) said reference plane being above said first and second gas-fired burner (41, 42).
An oven as claimed in any of the previous claims, characterised in that said first and said second gas-fired burner (41, 42) exert their baking action on the foods, operating mainly by convection.
An oven as claimed in any of the previous claims, characterised in that said first and said second gas-fired burner (41, 42) are non grill burners.
An oven as claimed in any of the previous claims, characterised in that said first and said second burner (41, 42) can function simultaneously.
An oven as claimed in any of the previous claims, characterised in that said first and said second burner (41, 42) can be activated independently from each other.
An oven as claimed in any of the previous claims, characterised in that said means (40) for generating flames comprise a gas-fired grill burner (43).
An oven as claimed in any of the previous claims, characterised in that it comprises:
- a user interface (51) for selecting the desired baking program according to the type of food to be cooked in the inner compartment (2) or of the types of foods to be cooked simultaneously in the inner compartment (2);

- an electronic unit (53) controlling at least a part of said flame generating means (40), said electronic control unit (53) operating according to the baking program selected through the user interface (51).
An oven as claimed in claim 10, characterised in that according to the baking program selected through the user interface (51) said electronic unit (53) implements a time sequence of activation/deactivation of at least the first and/or the second burner (41, 42).
An oven as claimed in claim 11, characterised in that said time sequence is selected among a plurality of pre-determined and pre-stored time sequences, each associated to a cooking program, said time sequence being independent from thermodynamic parameters measurable in the inner compartment (2) during the baking operation.
An oven as claimed in claim 11, characterised in that the duration of at least one part of the activation and/or deactivation phases of the time sequence is equal to a predetermined value or it is determined by the reaching of a predetermined temperature in the inner compartment (2).
An oven as claimed in claim 11 or 12 or 13, characterised in that the time sequence of activation/deactivation implemented by the electronic unit (53) provides the regulation in time of the thermal power delivered by the first and/or by the second burner (41, 42), said thermal power of the first and/or of the second burner (41, 42) being able to assume at least two values different from zero.
An oven as claimed in claim 11 or 12 or 13 or 14 when it depends on claim 9, characterised in that said time sequence of activation/deactivation involves, in addition to the first and to the second burner (41, 42), also the grill burner (43).
An oven as claimed in any of the claims 11 through 15 when it depends on claim 3, characterised in that the predetermined time sequence is calibrated to uniform the baking times of a first and of a second food placed simultaneously on the first and on the second support (31, 32).
An oven as claimed in any of the previous claims, characterised in that said inner compartment (2) is at least partly identified by a lower base (22) and by a ceiling (21) opposite to each other.
An oven as claimed in any of the claims 1 through 16, characterised in that said inner compartment (1) is at least partly identified by:
- an opening (230) that enables to introduce and extract foods from said inner compartment (2), said opening (230) being closable by a door (23);

- a bottom surface (24) opposite to said door (23) at least when said door is in closed position;

- a lower base (22) and a ceiling (21) that develop between said door (23) and said bottom surface (24);

- two opposite lateral surfaces (25, 26) that develop between said base (22) and said ceiling (21).
An oven as claimed in claim 17 or 18, characterised in that said reference plane orthogonal to said ideal reference straight line coinciding with the physical vertical passes through the point of said first support (31) that is closest to the lower base (22).
An oven as claimed in claim 17 or 18 or 19, characterised in that the first support (31), when it is in an operative position, is interposed between the lower base (22) and the ceiling (21) and it is at a distance different from zero from said lower base (22).
An oven as claimed in any of the claims 17 through 20 when it depends on claim 9, characterised in that the grill burner (43) is positioned at the ceiling (21).
An oven as claimed in any of the claims 17 through 21, characterised in that said first and/or said second gas-fired burners (41, 42) are in proximity to the lower base (22).
An oven as claimed in any of the claims 18 through 22, characterised in that said second burner (42) is in proximity to said bottom surface (24).
An oven as claimed in any of the claims 18 through 23, characterised in that said second burner (24) develops along a direction joining said two lateral surfaces (25, 26).
An oven as claimed in any of the claims 18 through 24, characterised in that said first burner (41) develops between said door (23) and said second burner (42).
An oven as claimed in any of the claims 18 through 25 when it depends directly or indirectly on claim 2, characterised in that said first shelf (310), when it is in said inner compartment (2), is positioned at a predetermined distance from the bottom surface (24), to promote the upwards convective motion of heat.
An oven as claimed in any of the claims 17 through 26, characterised in that said lower base (22) has a plurality of holes (220) to enable a better distribution in the inner compartment (2) of the heat coming from the first burner (41), when said first burner (41) is positioned underneath said lower base (22).
An oven as claimed in any of the claims 17 through 27, characterised in that said first burner (41) is underneath said lower base (22).
An oven as claimed in any of the previous claims, characterised in that said first burner (41) is underneath the first support (31).
An oven as claimed in any of the previous claims, characterised in that it comprises a fan (6) that moves the air of the inner compartment (2).