WO2007144432A1

WO2007144432A1 - Apparatus for preparing food and air guide member therefor

Info

Publication number: WO2007144432A1
Application number: PCT/EP2007/055993
Authority: WO
Inventors: Fedde Van Der Weij
Original assignee: Kavaring Cooking Systems B.V.
Priority date: 2006-06-16
Filing date: 2007-06-18
Publication date: 2007-12-21
Also published as: JP5756494B2; PL2034872T3; JP6211659B2; KR101482581B1; CN101500462A; CA2655284A1; EP2034872A1; AU2007259266B2; US20090134140A1; MX2008016234A; JP2013174436A; JP5340142B2; DE602007006016D1; EP1867264A1; RU2444971C2; AU2007259266A1; KR20090023673A; JP2014185849A; ATE464823T1; EP2034872B9

Abstract

Apparatus for preparing food, comprising a food preparation chamber (2) with an air-permeable bottom wall (5) and an upper air discharge opening (6), a fan (7) for moving hot air succesively through the bottom wall (5), the food preparation chamber (2) and the discharge opening (6), air guide means (9) for returning the air from the discharge opening (6) towards the bottom wall (5) separate from the food preparation chamber (2), heat radiating means (10) positioned in the upper part of the food preparation chamber (2) and an air guide member (II) below the food preparation chamber (2). The air guide member (II) is provided for directing the air flow essentially upwards into food present in the food preparation chamber (2).

Description

Apparatus for preparing food and air guide member therefor

The invention firstly relates to an apparatus for preparing food, comprising a food preparation chamber with an air-permeable bottom wall and an upper air discharge opening, a fan for moving hot air succesively through the bottom wall, the food preparation chamber and the discharge opening, air guide means for returning the air from the discharge opening towards the bottom wall separate from the food preparation chamber, heat radiating means positioned in the upper part of the food preparation chamber and an air guide member below the food preparation chamber.

Such an apparatus is known, for example, from US- A-4.374.319 and from EP-A-284.420. In the known apparatus according to the former document the food preparation chamber is provided with a sliding shelf defining the bottom wall thereof. This sliding shelf is provided with an array of small perforations to admit hot air from a bottom air space (acting as air guide member) into the food preparation chamber. The hot air flows through the food preparation chamber as high velocity air streams. In the latter document figure 7 shows a space defined by a convex air guiding wall in parallel to and underneath the air-permeable bottom wall. The air is allowed to swirl in this space and is not directed upwards.

An apparatus of this type provides a method for the preparation of food wherein the food is heated from below (by means of the air flow) and from above (by the heat radiating means) simultaneously. The air, which is heated by the heat radiating means, circulates within the apparatus and prepares the food (frying, cooking) . It is an object of the present invention to provide an improved apparatus of the type referred to above.

Thus, in accordance with the present invention the air guide member is provided for directing the air flow es- sentially upwards into food present in the food preparation chamber.

In this aspect the phrase ^essentially upwards' basically tries to express that the radial component of the flow is bent essentially vertically upwards such that the flow essentially occurs upwards through the food. Such an upwardly directed air flow leads to an improved regular air flow pattern, compared to a situation in which the air would arrive at the bottom wall of the food preparation chamber with a considerable radially directed flow component (as will be the case, for example, in the apparatus according to the state of the art mentioned above) . As a result the food is prepared evenly.

Preferably the air guide member provides an unob- structed air flow pattern having the highest velocity in the center of the food preparation chamber and decreasing radially outward.

In this context ^unobstructed' means a situation in which no food is present in the food preparation chamber. However, the distribution of the air flow across the food preparation chamber will be influenced by the food. Generally the food will be positioned such that it provides the highest flow resistance in the center, decreasing radially outwards. In combination the velocity distribution and the resistance distribution will provide the desired regular flow pattern across the food preparation chamber (thus, for example, the ^obstructed' air flow velocity will be substantially constant across the entire food preparation chamber) . Preferably said air guide member comprises air guide ribs.

For example it is possible that said air guide ribs are arranged in vertical planes, extend radially and meet at a central location. Such ribs promote the upward air flow, prevent a circular (swirling) air flow and create a pressure increase towards the centre. Preferably, the air guide member comprises a frusto-conical upwardly tapering air guide part. Such air guide part is very effective in promoting the upward air flow. This part also may be combined with the above air guide ribs and be positioned concentrically therebelow. Constructively it is preferred that there are three or more air guide ribs substantially arranged as a cross with arms of equal length. Then, when there are four air guide ribs, these substantially are arranged in the shape of a Greek cross.

Although then, basically, the ribs would be straight, it is conceivable too that the individual air guide ribs have a curved extension, of which preferably the direction of curve is determined by the rotation direction of the fan such that the air converges in the center.

When, in accordance with another embodiment, the air guide ribs and, if provided, the air guide part define an assembly which is removable from the remainder of the apparatus, one can remove said air guide ribs for inspection, maintenance, cleaning or for interchanging it (depending on the specific use of the apparatus, e.g. the specific food to be prepared) .

When, in accordance with another preferred embodiment of the apparatus according to the present invention, the bottom wall of the food preparation chamber has, at least partly, an open structure, the air can flow easily through the bottom wall and can reach all sides of the food and can heat it very effectively. In this respect it should be noted that the state of the art shelf does not have an open structure, because the penetrations only define a very small part of the entire area of the shelf. Here, however, an open structure means that a substantial part of the area is open for the passage of the air flow.

Such an open structure can, for example, be achieved when the bottom wall of the food preparation cham- ber is, at least partly, defined by a grid or mesh structure. Then the openings even define the greater part of the area .

Preferably the food preparation chamber is con- structed in a manner as to provide a disposition of the food therein having a cross-sectional area increasing upwardly.

As a result the highest flow resistance can be obtained in the center of the food preparation chamber, which measure, as stated above, may have an advantageous effect on the operation of the apparatus.

Preferably at least the bottom wall of the food preparation chamber is corrugated. This may lead to a positioning of the food in the valleys of the corrugations, whereas the tops are free for the passage of the air, which disposition is advantageous in case of dense food which is not very permeable for air.

Further it is preferred that the food preparation chamber has a circumferential wall with a lower end extending downwardly beyond the connection between said circumfer- ential wall and the bottom wall of the food preparation chamber. Such lower end, which may be curved (for example inwardly) , is helpful in directing the flow of air into the food and prevents a return of the air into the air guide means . When the food preparation chamber is provided with a removable bottom wall, it can be replaced by another bottom wall or even other type of bottom wall more suited for the type of food to be prepared, if needed.

In yet another preferred embodiment of the appara- tus according to the present invention, the food preparation chamber is double-walled with an inner wall and an outer wall defining therebetween the air guide means for returning the air from the discharge opening towards the bottom wall and wherein said double-walled food preparation chamber is housed within an outer shell. In such an embodiment the heated air circulating within the apparatus does not come into contact with the outer shell which remains at a low, safe temperature.

It is possible that the air guide means for re- turning the air from the discharge opening towards the bottom wall comprise a number of distinct channels.

An extremely user friendly apparatus can be obtained when the food preparation chamber comprises an upper portion and a removable lower portion. The lower portion generally will contain the food to be prepared, and after removing it a user can shake it to disturb the food before again reinstalling the lower portion. This offers a user the possibility to at a certain level control the food preparation process in accordance with its own wishes. The user does not have to reach within the food preparation chamber and therefore stays safely away from the circulating heated air and from the heat radiating means.

For example it is possible that the lower part of the food preparation chamber comprises a grip and a basket- like member within the double wall. The grip makes the handling of the lower part easy, whereas the basket-like member provides a good flow pattern for the air flow.

Such a basket-like member can have an inverted frusto-conical shape, which will lead to a corresponding disposition of the food with favorite flow characteristics therethrough.

For safety reasons it may be advantageous if means are provided for deactivating the heating means and/or stopping the air flow between the inner and outer walls when the upper and lower portion of the food preparation chamber are separated. As a result no dangerous situations can occur when a user for example removes the lower part without deactivating the apparatus.

For example such means may comprise a switch coop- erating with the removable portion of the food preparation chamber. When the lower portion is removed the switch is operated. However, other positions of such a switch are conceivable too.

Constructively there are many options for further realising the apparatus. For example the basket-like member may be removable wherein the grip comprises activatable latching means for connecting and disconnecting the removable basket-like member.

For obtaining a good connection and sealing be- tween the upper and lower portion of the food preparation chamber it is possible that means are provided for preloading the lower portion towards the upper portion of the food preparation chamber.

Such means may comprise spring means located un- derneath the lower portion.

Because during preparation of food within the basically closed system within the apparatus a pressure rise will occur, the food preparation chamber preferably is provided with a pressure relief valve, or openings to release pressure and steam. These openings can be provided with a filter to reduce fumes and exhaust of fat particles.

It is possible that both the upper portion and lower portion are provided with a grip.

For example, when the lower and upper portion are assembled, the grips together define a unitary combined grip, for example by being nested or by being arranged closely alongside each other.

When in the air guide means for returning the air from the discharge opening towards the bottom wall verti- cally extending air guides are provided, a circumferential, swirling air flow in said air guide means may be prevented.

It is favourable too that at the start of the air guide means for returning the air from the discharge opening towards the bottom wall, above the food preparation chamber, radially extending air guides are provided. This also encourages a proper air flow in said air guide means.

Preferably, in such a case, said radially extending air guides are part of a heat reflector means defining the top of the food preparation chamber.

Such a heat reflector means may be removable.

The invention secondly relates to an air guide member presenting all the features of the air guide member provided in the apparatus in accordance with the present in- vention.

Hereinafter the invention will be elucidated while referring to the drawings in which:

Fig.l shows an embodiment of the apparatus according to the invention in a schematical vertical cross- sectional view;

Fig.2 schematically shows two different configurations of a bottom;

Fig.3 perspectively shows two different configurations of air guide ribs; Fig.4 shows another embodiment of the apparatus according to the invention in a schematical vertical cross- sectional view;

Fig.5 shows three different grip configurations;

Fig.6 perspectively shows an embodiment of a heat reflector;

Fig.7 shows, in a schematical vertical cross- sectional view, an embodiment of the apparatus according to the invention destined to be built-in in a surface, and

Fig.8 shows an alternative configuration of air guide ribs.

Referring to figure 1 the apparatus comprises an outer shell 1 which may be fabricated of a plastic material. Within said shell 1 a double-walled food preparation chamber 2 is defined surrounded by an inner wall 3 and an outer wall 4. In its bottom part the inner wall 3 is provided with an air-permeable bottom section 5. At its top, the inner wall is provided with a discharge opening β for air.

Above the discharge opening 6 a fan 7 is positioned which is driven by an electric motor 8 (of which the speed may be controllable) . By means of the low pressure caused at one side of said fan 7 air is sucked from the food preparation chamber 2 through the discharge opening 6, and is delivered at a high pressure in a channel 9 defined between the inner wall 3 and outer wall 4. Thus the air is forced through said channel 9 towards and through the air- permeable bottom section 5 of the inner wall 3 to arrive again at the food preparation chamber 2.

It is noted that, although figure 1 suggests that the channel 9 between the inner wall 3 and outer wall 4 con- tinuously surrounds the food preparation chamber 2 to define an annular channel, it also conceivable that there are a number of distinct channels leading from the fan 7 towards the bottom section 5.

In the upper part of the food preparation chamber one (or a number of) heat radiating means 10 is positioned which not only radiates heat into the food preparation chamber and towards any food present therein, but also heats the air circulating in the apparatus and flowing upwardly past said heat radiating means 10. Thus, food in the food preparation chamber 2 is heated simultaneously in two different manners: by heat radiated from the heat radiating means 10 and by the heated air passing the food from below.

Below the bottom section 5 sitting on the outer wall 4 is air guide member 11. The arrangement and/or shape of this air guide member 11 is such that the arriving air is directed upwardly through the bottom section 5 and into the food preparation chamber 2 with a regular flow pattern. This means that the air guide member 11 causes an essentially up- wardly directed air flow along the food present in the food preparation chamber 2. As a result across the entire cross- section of the food preparation chamber 2 the interaction between the heated air and the food is substantially equal. Another posibility is that the air guide member sitting on the outer wall 4 provides an unobstructed air flow pattern (that means without the presence of food) having the highest velocity in the central location of the food preparation chamber 2 and decreasing radially outward. Then, when food is present the resulting air flow can have the required regular pattern.

As shown schematically in figure 1, the bottom section 5 of the inner wall 3 of the food preparation chamber has, at least partly, an open structure, for example by being defined by a grid or mesh structure. Whereas in figure 1 the bottom section 5 connects to the lowermost part of the inner wall 3, figure 2 shows two alternative embodiments in which the food preparation chamber 2 has a circumferential wall 3' with a lower end 3" extending downwardly beyond the connection between said circumferential wall 3' and the bottom section 5 of the food preparation chamber. In Figure 2A said lower end 3" is straight and in figure 2B it is curved inwardly. Such lower end 3" prevents a disturbance of the upward airflow by the downward airflow out of channel 9 (see figure 1). Again referring to figure 1 one can see that the food preparation chamber 2 comprises an upper portion 2' and a removable lower portion 2". The lower part 2" of the food preparation chamber comprises a grip 12. The bottom section 5 may be part of a basket-like member 13 (indicated in fig- ure 2) within the double wall. Basically such a basket-like member will comprise (vertically or inclined) upwardly extending walls (e.g 13' in figure 2) and a horizontally extending bottom wall which in the present embodiment is defined by the bottom section 5. The lower portion 2" of the food preparation chamber can be removed from the shell 1. A user then can inspect the food in the basket-like member 13 and can, if needed, shake the basket-like member for disturbing the food therein or may choose different settings for the operation of the apparatus by means of a control panel (to be discussed below) .

Not shown are means (for example valve members) which may be provided to automatically shut down the heat radiating means and/or automatically close the channel 9 when the lower part 2" is removed. This prevents an unwanted outflow of heated air out of the apparatus in such a situation. Neither shown are pressure relief means or filtration openings which may be provided to cope with an increasing pressure within the food preparation chamber due to the heating of the food.

As illustrated, for example in Figure 2 or figure 4, the upwardly extending walls 13' of the basket-like member 13 diverge in such a way that the basket-like member 13 has an inverted frusto-conical shape. As a result a disposition of the food therein having a cross-sectional area increasing upwardly is provided which can be helpful in obtaining the regular flow pattern and even processing or preparing of the food sought for. Finally on top of the shell 1 a control panel 14 is shown with which the operation of the apparatus can be controlled (e.g. by setting parameters such as temperature, heating time, flow velocity etcetera) .

Figure 3 shows two embodiments of an air guide member 11 comprising air guide ribs 15. Both in figure 3A and figure 3B these air guide ribs 15 are four in number and are arranged in vertical planes, extend radially and meet at a central location. The guide ribs substantially are arranged in the shape of a Greek cross. Such ribs 15 promote the upward air flow, prevent a circular (swirling) air flow and create a pressure increase towards the central location.

In Figure 3B underneath or combined with said air guide ribs and concentrically therewith a frusto-conical up- wardly tapering air guide part 11 is arranged. The upwardly tapering circumferential surface 16 of this air guide part 11 helps in directing air arriving from the channel 9 (see figure 1) upwardly into the food preparation chamber 2.

Figure 8 shows a top plan view of an alternative embodiment of the air guide ribs 15' with a curved extension, of which preferably the direction of curve is determined by the rotation direction of the fan such that the air converges in the center.

The air guide ribs 15 or 15' and, if provided, the air guide part 11 may define an assembly which is removable from the remainder of the apparatus.

Figure 4 illustrates, in a view similar to figure 1, an alternative embodiment of the apparatus. Only the differences with respect to the embodiment according to figure 1 will be discussed.

In channel 9 for returning the air from the discharge opening 6 towards the bottom wall 5 vertically extending air guides 17 are provided. These air guides 17 are useful in preventing a circumferential, swirling air flow in said channel 9.

In the upper part of the food preparation chamber 2 a heat reflector 18 is provided, which is shown in more detail in figure 6. This heat reflector 18 comprises a central opening 19 defining the discharge opening 6. Further this heat reflector 18 defines radially extending air guides 20 which then are positioned at the start of the channel 9 for returning the air from the discharge opening 6 towards the bottom wall 5. These air guides 20 also prevent a circumferential flow of the air in the channel 9, in addi- tion to the air guides 17. Said heat reflector 18 may be removable .

Finally, in figure 4, there are shown means 21 which are provided for preloading the lower portion 2" to- wards the upper portion 2' of the food preparation chamber. Such means may comprise spring means 22 located underneath the lower part of the food preparation chamber 2. A safety switch as mentioned before may be integrated in these means 21. Figure 5 shows alternative grip embodiments. Figures 5A and 5B show a lower portion 2" with first grip part 23 and a basket 13 with second grip part 24. In the assembled position (figure 5A) the grip parts 23 and 24 are nested to define a unitary combined grip. Figures 5C and 5D show a basket 13 with grip 25 which is provided with a manually operable locking mechanism 26, and a lower portion 2" with locking part 27 cooperating with the locking mechanism 26 of the grip 25 when the basket 13 is positioned within the lower portion 2". Figure 5E illustrates a basket 13 with grip part

28 and lower portion 2" with grip part 29. In the illustrated assembled position the grip parts 28 and 29 are positioned in a common vertical plane one above the other. For removing the basket 13 from the lower portion 2" the basket first should be rotated in such a manner that both grip parts 28 and 29 are no longer positioned in a common plane. Of course other grip embodiments are conceivable, such as for example grip parts of the basket and lower portion which in the assembled position are located closely alongside each other.

Finally figure 7 illustrates an embodiment of the apparatus which can be built-in in a surface 30, for example a table top. The invention is not limited to the embodiments described before which may be varied widely within the scope of the invention as defined by the appending claims.

Claims

1. Apparatus for preparing food, comprising a food preparation chamber with an air-permeable bottom wall and an upper air discharge opening, a fan for moving hot air succe- sively through the bottom wall, the food preparation chamber and the discharge opening, air guide means for returning the air from the discharge opening towards the bottom wall separate from the food preparation chamber, heat radiating means positioned in the upper part of the food preparation chamber and an air guide member below the food preparation chamber, characterized in that the air guide member is provided for directing the air flow essentially upwards into food present in the food preparation chamber.

2. Apparatus according to claim 1, wherein the air guide member provides an unobstructed air flow pattern hav- ing the highest velocity in the center of the food preparation chamber and decreasing radially outward.

3. Apparatus according to claim 1 or 2, wherein said air guide member comprises air guide ribs.

4. Apparatus according to claim 3, wherein said air guide ribs are arranged in vertical planes, extend radially and meet at a central location.

5. Apparatus according to any of the previous claims, wherein the air guide member comprises a frusto- conical upwardly tapering air guide part.

6. Apparatus according to claim 4 or 5, wherein there are three or more air guide ribs substantially arranged as a cross with arms of equal length.

7. Apparatus according to any of the claims 4-6, wherein the individual air guide ribs have a curved exten- sion.

8. Apparatus according to any of the claims 4-7, wherein the air guide ribs and, if provided, the air guide part define an assembly which is removable from the remainder of the apparatus.

9. Apparatus according to any of the previous claims, wherein the bottom wall of the food preparation chamber has, at least partly, an open structure.

10. Apparatus according to claim 9, wherein the bottom wall of the food preparation chamber is, at least partly, defined by a grid or mesh structure.

11. Apparatus according to any of the previous claims, wherein the food preparation chamber is constructed in a manner as to provide a disposition of the food therein having a cross-sectional area increasing upwardly.

12. Apparatus according to any of the previous claims, wherein at least the bottom wall of the food prepa- ration chamber is corrugated.

13. Apparatus according to any of the previous claims, wherein the food preparation chamber has a circumferential wall with a lower end extending downwardly beyond the connection between said circumferential wall and the bottom wall of the food preparation chamber.

14. Apparatus according to claim 13, wherein said lower end of the circumferential wall is curved.

15. Apparatus according to any of the previous claims, wherein the food preparation chamber is provided with a removable bottom wall.

16. Apparatus according to any of the previous claims, wherein the food preparation chamber is double- walled with an inner wall and an outer wall defining therebetween the air guide means for returning the air from the discharge opening towards the bottom wall and wherein said double-walled food preparation chamber is housed within an outer shell.

17. Apparatus according to any of the previous claims, wherein the air guide means for returning the air from the discharge opening towards the bottom wall comprise a number of distinct channels.

18. Apparatus according to any of the previous claims, wherein the food preparation chamber comprises an upper portion and a removable lower portion.

19. Apparatus according to claim 18 in combination with claim 16, wherein the lower portion of the food preparation chamber comprises a grip and a basket-like member within the double wall.

20. Apparatus according to claim 19, wherein the basket-like member has an inverted frusto-conical shape.

21. Apparatus according to any of claims 18-20, wherein means are provided for deactivating the heating means and/or stopping the air flow between the inner and outer walls when the upper and lower portion of the food preparation chamber are separated.

22. Apparatus according to claim 21, wherein said means comprise a switch cooperating with the removable portion of the food preparation chamber.

23. Apparatus according to any of the claims 19-

22, wherein the basket-like member is removable and wherein the grip comprises activatable latching means for connecting and disconnecting the removable basket-like member.

24. Apparatus according to any of the claims 18- 23, wherein means are provided for preloading the lower portion towards the upper portion of the food preparation chamber.

25. Apparatus according to claim 24, wherein said means comprise spring means located underneath the lower portion.

26. Apparatus according to any of the previous claims, wherein the food preparation chamber is provided with a pressure relief valve.

27. Apparatus according to any of the previous claims in combination with claim 18, wherein both the upper portion and lower portion are provided with a grip.

28. Apparatus according to claim 24, wherein when the lower and upper portion are assembled, the grips together define a unitary combined grip, for example by being nested or by being arranged closely alongside each other.

29. Apparatus according to any of the previous claims, wherein in the air guide means for returning the air from the discharge opening towards the bottom wall vertically extending air guides are provided.

30. Apparatus according to any of the previous claims, wherein at the start of the air guide means for returning the air from the discharge opening towards the bot- torn wall, above the food preparation chamber, radially extending air guides are provided.

31. Apparatus according to claim 30, wherein said radially extending air guides are part of a heat reflector means defining the top of the food preparation chamber.

32. Apparatus according to claim 31, wherein said heat reflector means is removable.

33. Air guide member presenting all the features of the air guide member disclosed in any one of the previous claims and being thus constructed and evidently intended for use in the apparatus as claimed in any one of the previous claims .