BAKING TRAY FOR USE IN A COOKING DEVICE AND COOKING DEVICE COMPRISING SUCH A BAKING TRAY

Technical Field

The invention relates to a baking tray for use in a cooking device , in particular an oven . Furthermore , the invention relates to a cooking device comprising said baking tray . Another part of the invention relates to a method for manufacturing said baking tray .

Background Art

Baking trays are used for supporting foods inside a cooking chamber of a cooking device of a private household, in particular a baking oven or a steam oven . Before inserting food into the cooking chamber, the user might preheat the baking tray inside the cooking chamber . In a second scenario , the user might not preheat the baking tray and might insert a cold baking tray together with the food into the cooking chamber . In a third scenario , the user might preheat a baking stone and uses it for a better cooking result . The cooking result will be di f ferent in these three scenarios .

An improvement of these three scenarios is the use of baking trays which comprise local heater elements for heating the baking tray inside the cooking chamber . The baking tray is connected with a power source of the cooking device in order to operate the heater elements of the baking tray . This arrangement accelerates the heating of the baking tray inside the cooking chamber . However, the thermal ef ficiency of such baking trays is unsatis factory . Alternatively, a baking stone can be equipped with local heater elements .

However, the maximum temperature of a baking oven in a private household is limited and even the use of baking trays or baking stones with local heater elements do not solve the problem that in certain cooking scenarios even more heat would be required in order to achieve an optimal cooking result . For example , Pi z za, Tarte Flambee or certain types of bread cannot optimally be cooked in known baking ovens since not enough heat is provided by known baking trays or baking stones with or without local heater elements .

Disclosure of the Invention

The problem to be solved by the present invention is therefore to provide a baking tray for a better cooking result in a cooking device .

This problem is solved by the subj ect of independent claim 1 . According to this , a baking tray for use in a cooking device , in particular a baking oven or a steam oven, comprises a bottom element made of aluminium alloy and a tubular heater . "Made of aluminium alloy" means that the baking tray bottom element is made of an alloy in which aluminium is the predominant metal . The "bottom element" is the supporting element for supporting the food inside a cooking chamber .

In particular, a tubular heater is a metal- sheathed and deformable heater with a round or oval cross-section . In particular, the heater can be made of a NiCR alloy, the sheath material can be made of an aluminium alloy or CrNi steel . An insulating material could be magnesium oxide .

On the one hand, aluminium is a very good heat conductor . Heat trans ferred from the tubular heater to the bottom element made of aluminium alloy is distributed quickly over the entire bottom element . On the other hand, aluminium can be used for casting a baking tray in order to produce an optimally formed baking tray . Such a baking tray can be heated quickly inside a cooking chamber which leads to a better cooking result and a better thermal ef ficiency .

For example , a Pi z za, Tarte Flambee or certain types of bread can be better cooked by using such a baking tray . I f French fries are cooked on such a baking tray, they become crispy even i f the user does not turn the fries during cooking .

Advantageously, the tubular heater has the form of a wavy line and the tubular heater can extend over the entire bottom element . "Extend over the entire bottom element" means , that the tubular heater is distributed over the entire bottom element . There is no part of the bottom element which is not heated by the tubular heater . The tubular heater with the form of a wavy line and an even distribution of the entire bottom element heats the bottom element uni formly such that equal cooking results can be expected everywhere on the baking tray .

In particular, the bottom element is a casting . With other words , the bottom element is made by a manufacturing process in which a liquid aluminium alloy is poured into a mould, which contains a hollow cavity of the desired shape , and then allowed to solidi fy . Casting is used for making a complex shape of the baking tray .

Advantageously, the tubular heater is casted in the bottom element . This means , that the tubular heater is surrounded by the casted aluminium alloy . During the manufacturing process , the tubular heater is arranged in the empty mould . Liquid aluminium alloy is poured into the mould such that liquid aluminium alloy surrounds the tubular heater at least partly and encloses the tubular heater .

The baking tray has an optimal heat trans fer from the tubular heater to the bottom element . Since the aluminium alloy surrounds the tubular heater, the heat trans fer area between the tubular heater and the casted aluminium alloy is very large . The baking tray can be heated very quickly .

In particular at least 60% , in particular at least 80% , in particular at least 90% , of the outer surface of the tubular heater is surrounded by the bottom element . It is not necessary that the complete outer surface of the tubular heater is surrounded by the aluminium alloy . A good heat trans fer is ensured even i f only one part of the tubular heater touches the bottom element .

Advantageously, the bottom element comprises at least one heater rip enclosing a section of the tubular heater and/or at least one stability rip not enclosing a section of the tubular heater . Heater rips enclose the tubular heater and trans fer the heat generated by the tubular heater to other parts of the bottom element . Stability rips are additional rips arranged at the bottom element which do not enclose tubular heater but improve the mechanical stability of the bottom element . In particular, the stability rips can comprise a wire or a tube , in particular made of steel . Alternatively, the stability rips could be substituted by steel wire or steel tubes attached to the bottom element .

In particular, the baking tray comprises a temperature sensor . The temperature sensor measures the temperature at at least one position of the baking tray . The power of the tubular heater can be controlled more precisely using the temperature data generated by the temperature sensor .

Furthermore , the temperature sensor can be arranged closer to an edge of the baking tray than to the centre of the baking tray . Arranging the temperature sensor in an outer area of the baking tray simpli fies the connection between the temperature sensor and a connecting element connecting the baking tray with the cooking device .

Advantageously, the temperature sensor is arranged at one of the at least one stability rips or is spaced from one of the at least one stability rips not more than 3 cm, in particular not more than 2 cm . Since the stability rip provides a good heat trans fer between di f ferent locations on the baking tray, the temperature sensor measures at the stability rip or close to the stability rip a temperature representing the temperature of another part , in particular a centre part , of the baking tray . It can be avoided that the temperature measures locally low values or locally high values of the temperature of the baking tray .

In particular, the temperature sensor is spaced at least 0 . 5 cm, in particular at least 1 cm, in particular at least 2 cm, from the heater rip . A minimum distance to the heater rip ensures that the temperature sensor measures an average temperature of the bottom element and not a local high temperature caused by heat emitted by the tubular heater .

Advantageously, the tubular heater comprises a PTC-Heater, which is a positive temperature coef ficient heater, and/or the tube of the tubular heater is made of aluminium alloy or steel .

In particular, the baking tray comprises a connecting element , in particular one single connecting element , for electrically connecting the tubular heater and the temperature sensor with a cooking device , in particular a baking oven . The connecting element connects the temperature sensor and the tubular heater together with the device control and the power source of the cooking device .

Furthermore , the initially mentioned problem is solved by a cooking device comprising a cooking chamber, a device control and a baking tray described above . The baking tray is arranged in the cooking chamber .

Advantageously, the cooking device comprises a receiving element for receiving the connecting element of the baking tray, wherein the receiving element is arranged at a back wall or at a side wall of the cooking chamber .

Furthermore , the device control can be adapted to limit the air temperature inside the cooking chamber to a first temperature i f the baking tray is arranged in the cooking chamber, and to a second temperature i f the baking tray is not arranged in the cooking chamber . In particular the second temperature is higher than the first temperature . This control of the air temperature inside the cooking chamber avoids an overheating of the baking tray . I f the baking tray is heated by the tubular heater, the air temperature is kept below a certain temperature .

Advantageously, the device control is adapted to deactivate the tubular heater i f the temperature sensor measures a temperature exceeding a predefined temperature limit . This is a further safety mechanism in order to avoid an overheating of the baking tray .

Advantageously, the cooking device comprises an input device , in particular a touch screen, adapted such that a user can select a cooking chamber air temperature and a baking tray temperature independently from each other via the input device . In particular, the device control is adapted to identi fy, i f the temperatures selected by the user cannot be maintained or reached by the cooking device , in particular wherein the device control can communicate this identi fication to the user via an output device .

Furthermore , the invention is related to a method for manufacturing the baking tray described above . The method comprises the following steps :

- arranging the tubular heater in a mould,

- pouring liquid aluminium alloy in the mould and casting in the tubular heater . The method ensures that the tubular heater is enclosed by the aluminium alloy such that heat can ef ficiently be trans ferred from the tubular heater to the aluminium alloy . In particular the method comprises the step of applying a surface finish to the bottom element .

Other advantageous embodiments are listed in the dependent claims as well as in the description below .

Brief Description of the Drawings

The invention will be better understood and obj ects other than those set forth above will become apparent from the following detailed description thereof . Such description makes reference to the annexed drawings , wherein :

Fig . 1 shows a front view of a cooking device with a baking tray according to the invention;

Fig . 2 shows the baking tray with view from the top ;

Fig . 3 shows a first sectional view of the baking tray;

Fig . 3a shows a detail view of Fig . 3 ;

RECTIFIED SHEET (RULE 91) ISA/EP Fig. 4 shows a second sectional view of the baking tray; and

Fig. 5a-5e show a method for manufacturing a baking tray according to the invention.

Modes for Carrying Out the Invention

Fig. 1 shows a household cooking device with a view from the outside to the front. The cooking device 1 is a baking oven. The terms "left", "right", "behind", "top", "bottom" are understood from the perspective of a user with a front view as shown in Fig. 1. The front of the cooking device 1 is defined as the position where the door 5 of the cooking device 1 is arranged.

The cooking device 1 comprises a housing 2 and a cooking chamber 3. The cooking chamber 3 is arranged in the housing 2. One or more food supports are arranged in the cooking chamber 3. The food supports can be designed, for example, as a grid, a baking tray or the like. The cooking device 1 shown in Fig. 1 comprises only one baking tray 4. The cooking chamber 3 is accessible to the user via a door 5. The door 5 comprises a door handle 6 with which the door 5 can be opened by hand. A heating chamber is arranged behind the cooking chamber 3 and is separated from the cooking chamber 3 by a back wall 7. The back wall 7 comprises air openings 8. Air is blown through theses air openings 8 between the cooking chamber 3 and the heating chamber by a fan arranged behind the back wall 7 in the heating chamber.

Fig. 2 shows the baking tray 4 of Fig. 1 with view from the top. The baking tray 4 comprises a bottom element 11. The bottom element 11 is surrounded by edges 12. The bottom element 11 is a casting made by aluminium alloy. A surface finish 13 is applied to the top side of the bottom element 11. The surface finish could be a solgel coating or a plasma coating. Fig. 3 shows a sectional view of the baking tray as defined by the dashed line shown in Fig. 2. Fig. 4 shows another sectional view of the baking tray as defined by the dashed line shown in Fig. 3.

A tubular heater 14 is cast into the bottom element 11. The tubular heater 14 is arranged on the bottom side of the baking tray 4 and has the form of a wavy line, i.e. the line runs with numerous turns. The tubular heater 14 extends over the entire bottom element 11, i.e. over the entire baking tray 4. With other words, the tubular heater 14 is bent and arranged such that the bottom element 11 is homogeneously heated by the tubular heater 14.

Fig. 3a shows a detail view of Fig. 3. It shows a sectional view with the cross-section of the tubular heater 14. In the present embodiment, the outer surface 15 of the tubular heater 14 is fully, i.e. 100% of the outer surface 15 of the tubular heater 14, surrounded by the bottom element 11. Heat can be transferred from the tubular heater 14 to the bottom element 11 via the whole circumference of the outer surface 15. Alternatively, only one part of the tubular heater 14 could be surrounded by the bottom element 11. The other part could protrude downwards from the bottom element 11 and could be surrounded by air. The letter embodiment would be thermally less efficient.

The part of the bottom element 11 which surrounds the tubular heater 14 and protrudes downwards from the bottom element 11 is defined as a heater rip 16. The heater rip 16 follows the complete course of the tubular heater 14.

Furthermore, the bottom element 11 comprises stability rips 17 which do not enclose the tubular heater 14 but improve the mechanical stability of the baking tray 4. On the other hand, stability rips 17 support the heat transfer between different locations of the baking tray 4 and improve a homogenous temperature distribution on the baking tray 4 .

A temperature sensor 18 is arranged at the bottom side of the baking tray 4 . It is arranged on an outer part of the baking tray 4 , i . e . it is arranged closer to an edge 12 than to the centre 19 of the baking tray 4 . Furthermore , the temperature sensor 18 is spaced from the tubular heater 14 by distance 20 of 2 cm such that the tubular heater 14 does not distort the measurement of the temperature of the baking tray 4 by the temperature sensor 18 .

The centre line of the tubular heater 11 represents the heater 21 . The heater 21 is a PTC-Heater which is enclosed by the tube 22 of the tubular heater 11 . The tube 22 is made of steel . Magnesium oxide is enclosed in the tube 22 .

The heater 21 and the temperature sensor 18 are electrically connected with the cooking device 1 via a connecting element 23 . The connecting element 23 comprises two plugs for the heater 21 and one plug for the temperature sensor 18 .

I f the user inserts the baking tray 4 into the cooking chamber 3 , the connecting element 23 connects with a receiving element 24 arranged at the back wall 7 of the cooking chamber 3 .

Since the bottom element made of aluminium alloy has a low melting temperature compared to other metals , the device control 25 limits the air temperature inside the cooking chamber 3 i f the baking tray 4 is inserted into the cooking chamber 3 . For example , the air temperature is limited to 250 ° C . The device control 25 deactivates the tubular heater 14 i f the temperature sensor 18 measures a temperature exceeding a predefined temperature limit , for example 220 ° C .

Fig . 5a to 5e illustrate several steps of a method for manufacturing the described baking tray 4 . Fig . 5a shows a mould 31 and the tubular heater 14 . The tubular heater 14 is arranged inside the mould 31. In a next step, liquid aluminium alloy is poured into the mould 31. The liquid aluminium alloy casts in the tubular heater 14 such that the tubular heater 14 is completely enclosed by the liquid aluminium alloy.

Fig. 5b shows a closing part 32 which closes the mould 31. The liquid aluminium alloy solidifies as shown in Fig. 5c. The mould 31 and the closing part 32 are detached from casting 33 as shown in Fig. 5d. Casting 33 comprises the bottom element 11 and the tubular heater

14. A surface finish 13 is applied on the top side of the casting 33 as shown in Fig. 5e.