OVEN WITH AIR NOZZLES AND MOVABLE MECHANISM THAT CAN BE OPENED / CLOSED OVER THE NOZZLES

Description

Technical Field

[0001] The present invention relates to an oven wherein the dirt on the oven base can be cleaned in household ovens with air impingement jet technology.State of the Art

[0002] Today, the air impingement jet technology is used in ovens for various cooking applications. In the ovens with air impingement jet technology, high-speed jets of hot air impinge a foodstuff vertically and / or impinge cooking members or trays carrying foodstuffs. Hot air jets are delivered by means of nozzles. Said nozzles are generally placed on the upper and lower walls of the oven so as to be perpendicular to the foodstuff. In said ovens, high-speed jets of hot air impinge the foodstuff, thus providing more homogeneous heat distribution rates or shorter cooking times.

[0003] One of the most common problems in state of the art household ovens with air impingement jet technology is the cleaning of the bottom of the oven which is contaminated during the cooking of the foodstuff. This problem especially arises while placing the tray or oven accessories into the oven or removing the same from the oven after the cooking process. One of the most common problems is that oil or foodstuff liquids can easily spill onto the base due to the fact that the tray becomes both heavy and hot and slips on the wire rack during the cooking process performed with accessories such as Pyrex, etc. While the dirt on the floor can be cleaned manually after the cooking process in conventional ovens, this is not possible in the ovens with the air impingement jet technology with nozzles.

[0004] In the ovens with the air impingement jet technology, the problem of cleaning the bottom surface of the oven if anything or oil spills during cooking due to the nozzles on the bottom arises. Difficult-to-clean substances such as sauce or oil flowing from the lower nozzle openings collect on the oven bottom, causing the problem of the dirt burning or sticking due to the direct contact with the hot surface. Since the user cannot directly reach this surface, the problem of failing to clean the same arises.

[0005] In the state of the art Patent Application No. WO2010135693A1, an oven is disclosed, a jet nozzle which accelerates the hot air and which converts the airflow to create a relatively thin thermal boundary layer of hot air on the surface of foodstuff or any other material placed in the airflow. However, there is no explanation regarding the cleaning of jet nozzles and oven bottom in the ovens with the air impingement technology. Application JP 2016-128745A discloses a cooking oven comprising a removable tray with a plurality of jet nozzles.Brief Description of the Invention

[0006] The aim of the present invention is the realization of an oven comprising an air impingement jet technology which eliminates the problem of the liquids, which spill from the foodstuffs while said foodstuffs are being loaded into / unloaded from the oven, being burnt or getting stuck on the oven bottom due to high temperatures, thus providing ease of cleaning.

[0007] Another aim of the present invention is the realization of an oven comprising an air impingement jet technology, which allows regional cooking and wherein the air delivered by the jet nozzles during the cooking process can be controlled locally. Another aim of the present invention is the realization of an oven comprising an air impingement jet technology which eliminates the problem of the speed of the air, delivered by the nozzles close to the front wall of the oven, being low and hence the problem of nonhomogeneous cooking on the foodstuff surface.

[0008] Another aim of the present invention is the realization of an oven comprising an air impingement jet technology which eliminates the problem, encountered in the state of the art, of the air losing speed while flowing from the rear side of the oven towards the front side thereof, which increase the flow speed of air towards the front side of the oven and which prevents the loss in speed and heat at the front wall region of the oven. Another aim of the present invention is the realization of an oven comprising an air impingement jet technology which eliminates the problem of the airtightness of the plates, whereon the nozzles are provided, being deteriorated due to the frequent detachment of the plates.

[0009] The oven realized in order to attain the aim of the present invention, explicated in the first claim and the respective dependent claims thereof, comprises an oven compartment which is defined by side walls, a rear wall, an upper wall, a lower wall and a door and wherein the foodstuffs to be cooked are placed by means of a cooking member; a lower plate which is provided on the lower wall; and a plurality of jet nozzles which are arranged on said lower plate. The oven of the present invention comprises a plate which is positioned over the jet nozzles on the lower plate so as to cover the entire surface of the jet nozzles, which has a movable mechanism that can be opened / closed over the jet nozzles and which has at least two guiding fins that are positioned at an angle with respect to each other in the open position such that the inner surface of the one faces the back surface of the other and that form a flat surface in the closed position.

[0010] In an embodiment of the present invention, the oven comprises a hidden tray which is disposed under the lower plate and which collects the liquids that may flow from the jet nozzles.

[0011] In an embodiment of the present invention, the oven comprises a large number of fins which are positioned on the plate in a gradual order and which has a monolithic structure with the plate.

[0012] In an embodiment of the present invention, the oven comprises the fins each having an angle of 0 degrees with respect to the plate when in the closed position and an angle with respect to the plate of 180 degrees when in the open position.

[0013] In an embodiment of the present invention, the oven comprises at least one hinge which is positioned at least one lower edge of the door and which aligns with the lower side of at least one of the side walls and which triggers the fins so as to enable the same from shifting from the open position to the closed position or from the closed position to the open position; and a hinge system which can move forwards and backwards on the lower side of at least one of the side walls.

[0014] In an embodiment of the present invention, the oven comprises the hinge which is disposed at the lower edge of the door aligning with the lower side of the first side wall or at the lower edge of the door aligning with the lower side of the second side wall or at both lower edges of the door; and a hinge system which is connected to said hinge and which can move forwards and backwards on the lower side of the first side wall or on the lower side of the second side wall or on the lower side of both side walls.

[0015] In another embodiment of the present invention, the oven comprises a display which has automatic menus for enabling the user to select the type of foodstuff to be cooked and also enabling the user to enter a desired cooking temperature and cooking time; at least one sensor which is disposed in the oven compartment and which measures the humidity in the oven; and at least one circuit board which receives humidity information from said sensor and which adjusts an air flow according to said information.

[0016] In another embodiment of the present invention, the oven comprises a control panel; at least one motor which moves the fins to bring the same to a certain position according to the information received from said electronic card; and at least two fins which are activated by being triggered by the motor.

[0017] In an alternative of the present invention, the oven comprises an oven compartment which is defined by side walls, a rear wall, an upper wall, a lower wall and a door and wherein the foodstuffs to be cooked are placed by means of a cooking member; a lower plate which is provided on the lower wall; and a plurality of jet nozzles which are arranged on said lower plate. The oven comprises a sheet which is disposed under the lower plate and which has holes as many as the number of jet nozzles on the lower plate and with the diameter equal to that of the jet nozzles, which are positioned so as to align with the bottom side of each jet nozzle.

[0018] In an embodiment of this alternative, the oven comprises a hidden tray which is disposed under the sheet and which collects the liquids that may flow from the holes.

[0019] In a further embodiment of this alternative, the holes of the sheet have the same dimensions or different dimensions according to the diameter of the jet nozzles.

[0020] In the alternative of the present invention, the oven comprises a sheet having at least one connection component which is positioned at at least one edge of the sheet so as to trigger the sheet to enable the sheet to move forwards and backwards; and at least one hinge which is connected to the at least one connection component and which is positioned at at least one lower edge of the door.

[0021] Said figures are: Figure 1: is the front perspective view of the oven when the door is in the open position. Figure 2: is the perspective view of the interior of the oven when the door is in the closed position. Figure 3: is the front perspective view of the oven when the door is in the closed position. Figure 4: is the front perspective view of the hidden tray. Figure 5: is the front perspective view of the oven door. Figure 6: is the front perspective view of the interior of the oven. Figure 7: is the assembly view of the lower plate and the fan sheet metal. Figure 8: is the assembly view of the lower plate and the hidden tray. Figure 9: is the perspective view of the placement of the lower plate and the sheet. Figure 10: is the front perspective view of the lower plate hinge system.

[0022] The following numerals are referred to in the description of the present invention: 1. Oven 2. First side wall 3. Second side wall 4. Rear wall 5. Upper wall 6. Lower wall 7. Door 7.1 Control panel 7.2 Knob 7.3 Display 7.4 Circuit board 7.5 Switch 7.6 Hinge 8. Fan 9. Motor 10. Fan sheet metal 10.1 Mounting housing 11. Oven compartment 12. Oven shelf 13. Upper plate 14. Lower plate 14.1 Claw 14.2 Catch 15. Jet nozzle 16. Fin 16.1 Fin inner surface 16.2 Fin back surface 17. Plate 18. Hidden tray 18.1 Connection member 19. Sheet 19.1 Hole 19.2 Connection component 20. Hinge assembly 21. Sensor h1: tray front height h2: tray back heightDetailed Description of the Invention

[0023] The oven (1) of the present invention comprises a first and second side wall (2, 3); a rear wall (4); an upper wall (5); a lower wall (6); and a door (7). A control panel is provided, which can be placed above, below or next to the door (7). An arm (not shown in the figures) is positioned on the door (7) so as to open the door (7) from top to bottom, from left to right or from right to left. The oven (1) comprises at least one fan (8) which is positioned on the rear wall (4), a circular heater which is disposed around the fan (8) and at least one motor (9). A fan sheet metal (10) which is mounted on the rear wall (4) by being screwed at the corners is provided in front of said fan (8) and the heater.

[0024] The oven (1) comprises an oven compartment (11) which is defined by the side walls (2, 3), a rear wall (4), an upper wall (5), a lower wall (6) and a door (7). The oven (1) further comprises at least one sensor (21) which is disposed in said oven compartment (11) and which measures the humidity value in the oven (1). An oven shelf (12) is supported by any support member so as to be placed in the oven compartment (11). In an embodiment of the present invention, the oven shelf (12) is a standard oven grill. In an embodiment of the present invention, support members are positioned on the side walls (2, 3) so as to align with each other and face each other. The oven shelf (12) is placed on said support members and is positioned in the oven compartment (11). In different embodiments of the present invention, a large number of oven shelves (12) can be placed in the oven compartment (11) parallel to each other in the horizontal plane with a certain space therebetween.

[0025] The oven (1) comprises an upper plate (13) which is placed under the upper wall (5) and a lower plate (14) which is placed on the lower wall (6). Said upper plate (13) and lower plate (14) comprise a plurality of jet nozzles (15) arranged thereon in rows and columns. Said jet nozzles (15) are configured to transmit hot or cold impingement air towards the oven shelf (12) at a high speed. Relatively hot air entering the middle region of the fan sheet metal (10) passes through the fan (8) and the heater so as to be accelerated after passing through the upper plate (13) and the lower plate (14) to be directed onto the foodstuff surface. In the present invention, the jet nozzles (15) are shaped so as to form a flow pattern which enhances heat transfer on the surface of the foodstuff. Thus, a more homogeneous and high heat transfer distribution is obtained, which enables the foodstuffs to be cooked homogeneously and more quickly in the oven (1).

[0026] According to the present invention, the oven (1) comprises a plate (17) which is positioned over the jet nozzles (15) on the lower plate (14) so as to cover the entire surface of the jet nozzles (15), which has a movable mechanism that can be opened / closed over the jet nozzles (15) and which has at least two guiding fins (16) that are positioned at an angle with respect to each other in the open position such that the inner surface (16.1) of the one faces the back surface (16.2) of the other and that form a flat surface in the closed position.

[0027] In an embodiment of the present invention, the oven (1) comprises a plurality of fins (16) which are successively positioned on the plate (17) so as to cover the surface of all the nozzles (15) on the lower plate (14). Said fins (16) have a monolithic structure with the plate (17) whereon the former are positioned.

[0028] In an embodiment of the present invention, the oven (1) comprises at least one hinge which is positioned at at least one lower side of the side walls (2, 3) and which corresponds to the lower side of at least one of the side walls (2, 3); and a hinge system (20) which can move forwards and backwards along the y axis at the lower side of at least one of the side walls (2, 3).

[0029] In an embodiment of the present invention, the oven (1) comprises the hinge (7.6) which is disposed at the lower edge of the door (7) aligning with the lower side of the first side wall (2) of the oven (1) or at the lower edge of the door (7) aligning with the lower side of the second side wall (3) thereof or at both lower edges of the door (7); and a hinge system (20) which can move forwards and backwards on the lower side of said first side wall (2) of the oven (1) or on the lower side of the second side wall (3) thereof or on the lower side of both side walls (2, 3). Said hinge (7.6) and hinge system (20) are connected to each other.

[0030] In an embodiment of the present invention, the hinge system (20) moves forwards and backwards along the y axis at the lower side of the first side wall (2) of the oven (1), or at the lower side of the second side wall (3) thereof or at the lower side of both side walls (2, 3) thereof.

[0031] In an embodiment of the present invention, with the opening movement of the oven (1) door (7), the hinge system (20) is triggered from the hinge (7.6) on the door (7), thus enabling the fins (16) to be closed and forming a flat surface on the jet nozzles (15). When the fins (16) are in the closed position on the jet nozzles (15), the angle between the fins (16) and the surface of the jet nozzles (15) is 0 degree. Thus, liquids which may spill while placing foodstuffs in the oven (1) remain on the surface of the fins (16) and cannot reach the lower wall (6) of the oven (1). With the closing movement of the oven (1) door (7), the hinge system (20) is triggered from the hinge (7.6) on the door (7), thus enabling the fins (16) to open. Thus, the fins (16) switch to the open position to form an angle with the surface of the jet nozzles (15). The angle of said fins (16) when switching from the closed position to the open position is in the range of 0 to 180 degrees. When the door (7) is closed, the fins (16) are opened and the hot air outlet is provided from the jet nozzles (15) such that the air outlet speed is not affected.

[0032] In an embodiment of the present invention, the door (7) comprises a control panel (7.1) having at least one knob (7.2) positioned thereon and a display (7.3) having automatic menus for selecting the foodstuffs to be cooked and a timer and at least one circuit board (7.4) receiving the humidity value from the sensor (21) and accordingly adjusting an air flow; and a switch (7.5) which is disposed at the inner side of the door (7) and which can detect whether the door (7) is open or closed.

[0033] In an embodiment of the present invention, the oven (1) comprises a sensor (21) which measures the humidity content in the oven (1) and records said data; a control panel (7.1) which has a display (7.3) having menus where the user can select the type of foodstuff to be cooked and the temperature is automatically adjusted depending on said foodstuff type and where the user can enter a cooking time as per his / her preference and at least one circuit board (7.4) which receives humidity information from the at least one sensor (21) and adjusts an air flow according to this information; at least one motor which enables the fins (16) to be moved to a certain position depending on the information received from said circuit board (7.4); and at least two fins (16) which are activated by being triggered by the motor, which can be opened or closed on the jet nozzles (15) as required or which can be positioned at a certain angle to provide the necessary air flow according to the needs of the cooked foodstuff. In another embodiment of the present invention, the movement of the fins (16) on the jet nozzles (15) is automatically provided according to the foodstuff selection in the menus, the cooking function or the data of the sensor (21) in the oven (1), and the air flow balance is provided by changing the angle of the fins (16) according to the need. The jet nozzles (15) on the upper plate (13) and the jet nozzles (15) on the lower plate (14) are both active until a certain cooking level. After reaching a certain cooking level, the extra air flow required to better cook the top or bottom of the foodstuff to be cooked is directed by adjusting the angle of the fins (16). Surprisingly, it has been determined that only by this manner, the optimum internal cooking balance and the brownness of the bottom / top surface can be achieved for foodstuffs such as bread and pizza. For example, when a better brownness is desired while cooking pizza, halfway through the cooking time, the fins (16) move counterclockwise to direct the air towards the bottom, at a predetermined degree of n such that the bottom of the pizza is better cooked. In another example, when it is desired to better fry the top of the chicken while cooking chicken, the fins (16) provide an m-degree movement clockwise at a determined moment t of the cooking time, thus directing the air to the upper side this time.

[0034] In an embodiment of the present invention, the oven (1) comprises a hidden tray (18) which is positioned under the lower plate (14) and which allows the collection of liquids flowing from the plurality of jet nozzles (15). There is a gap between said hidden tray (18) and the lower plate (14) through which hot air passes. The grease and foodstuff liquids flowing from said jet nozzles (15) are collected in the hidden tray (18) disposed under the lower plate (14). Thus, since grease and foodstuff liquids do not come into direct contact with the hidden heater on the lower wall (6), the problem of said liquids being burnt or being difficult to clean is prevented.

[0035] In an embodiment of the present invention, in the oven (1) with the air impingement jet technology, when viewed from the front wall (7), the lower plate (14) has an inclination towards the rear wall (4). Thus, air flow is provided at the same time, and a homogeneous distribution of hot air is achieved while the weak air flow region between the jet nozzles (15) is strengthened.

[0036] In the present invention, the height of the hidden tray (18) disposed under the lower plate (14) has a decreasing height from the rear wall (4) part towards the front wall (7) part depending on the placement. The ratio of the front height (h1) of the hidden tray (18) to the rear height (h2) thereof is between 0.3 and 0.8. Thus, the flow of hot air passing between the hidden tray (18) and the lower plate (14) increases towards the front wall (7) and offers a more homogeneous air distribution. Consequently, the air flow difference between the rear wall (4) and the front wall (7) of the oven (1) is reduced. This ensures that the foodstuff in the tray or cooking member is cooked evenly.

[0037] The hidden tray (18) and the lower plate (14) are required to be removed and cleaned periodically. In an embodiment of the present invention, the hidden tray (18) and the lower plate (14) are removed and cleaned separately. There is at least one mounting housing (10.1) on the surface of the fan sheet metal (10) which is in contact with the edge of the lower plate (14). On the surface of the lower plate (14) in contact with the fan sheet metal (10), there is at least one claw (14.1) to be fitted into said at least one mounting housing (10.1). When the lower plate (14) having the jet nozzles (15) is desired to be cleaned, the claw (14.1) on the lower plate (14) is removed from the mounting housing (10.1) on the fan sheet metal (10), and the lower plate (14) is cleaned separately. On the part of the hidden tray (18) facing the front wall (7), there is a connection member (18.1) which enables the hidden tray (18) to be gripped and pulled out of the oven compartment (11) by being pulled. Thus, the hidden tray (18) is taken out of the oven compartment (11) and cleaned by means of this sliding structure.

[0038] In another embodiment of the present invention, the hidden tray (18) and the lower plate (14) are removed and cleaned together. As seen in Figure 8, the bottom plate (14) is mounted to the hidden tray (18) by engaging a catch (14.2), which is positioned on the part of the lower plate (14) facing the front wall (7), with the connection member (18.1) positioned on the part of the hidden tray (18) facing the front wall (7) so as to correspond to the catch (14.2). In an embodiment of the present invention, the connection of said catch (14.2) is provided by a spring mechanism. Said spring mechanism has a structure which can be gripped by the user by hand. The user takes out the hidden tray (18) and the lower plate (14) by holding this spring mechanism. Then, he / she separates the hidden tray (18) and the lower plate (14) from each other by lifting the catch (14.2). After being cleaned, the hidden tray (18) and the lower plate (14) are connected to each other outside and placed in the oven compartment (11).

[0039] In another embodiment of the present invention, the mounting of the lower plate (14) and the fan sheet metal (10) to each other by means of at least one claw (14.1) fitted into at least one mounting housing (10.1) as well as the mounting of the lower plate (14) to the hidden tray (18) by means of a catch (14.2) engaging with the connection member (18.1) can be used together in the same embodiment without changing the above-described embodiments.

[0040] In an alternative of the present invention, the oven (1) comprises a sheet (19) which has holes (19.1) positioned thereon, which has at least one connection component (19.2) and which is positioned between the lower plate (14) and the hidden tray (18). On said sheet (19), there are holes (19.1) as many as the number of jet nozzles (15) on the lower plate (14) and with the diameter equal to that of the jet nozzles (15). Said holes (19.1) are positioned on the sheet (19) so as to exactly align with the bottom side of each jet nozzle (15). Said connection component (19.2) is positioned on the sheet (19) so as to be connected to the hinge (7.3) on one lower edge of the door (7) or to the hinge (7.3) on the other lower edge thereof or the hinges (7.3) positioned on both lower edges thereof.

[0041] In the alternative of the present invention, with the opening movement of the oven door (7), the connection component (19.2) is triggered by the hinge (7.3), thus enabling the sheet (19) to move. During this movement, the sheet (19) moves forward as much as the diameter of one jet nozzle (15), and the closed part on the sheet (19) without holes (19.1) aligns with the jet nozzles (15), thus closing the jet nozzles (15). When the door (7) is closed, the sheet (19) moves in the opposite direction as much as the diameter of one jet nozzle (15). The holes (19.1) on the sheet (19) align with the bottom side of the jet nozzles (15), allowing the jet nozzles (15) to be opened. Thus, the air is directed into the oven (1) through the jet nozzles (15).

[0042] In an embodiment of the present invention, the sheet (19) is triggered by the hinge (7.3) and moves forwards and backwards along a y axis.

[0043] In an embodiment of the alternative of the present invention, the jet nozzles (15) through which the air exits may have the same or different dimensions. In this case, the dimensions of the holes (19.1) on the sheet (19) are also designed to have the same or different dimensions depending on the diameter of the jet nozzles (15). The dimensions of the jet nozzles (15) can also be adjusted to provide a homogeneous distribution of hot air.

Claims

1. An oven (1) comprising an oven compartment (11) defined by the side walls (2, 3), a rear wall (4), an upper wall (5), a lower wall (6) and a door (7) , at least one fan (8) positioned on the rear wall (4), a circular heater disposed around the fan (8) and at least one motor (9), a lower plate (14) provided on the lower wall (6); and a plurality of jet nozzles (15) arranged on said lower plate (14), characterized by a plate (17) positioned over the jet nozzles (15) on the lower plate (14) so as to cover the entire surface of the jet nozzles (15), which has a movable mechanism that can be opened / closed over the jet nozzles (15) and which has at least two guiding fins (16) that are positioned at an angle with respect to each other in the open position such that the inner surface (16.1) of the one faces the back surface (16.2) of the other and that form a flat surface in the closed position.

2. An oven (1) according to Claim 1, characterized by a hidden tray (18) which is disposed under the lower plate (14) and which collects the liquids that may flow from the jet nozzles (15).

3. An oven (1) according to Claim 1 or 2, characterized by a large number of fins (16) which are positioned on the plate (17) in a gradual order and which has a monolithic structure with the plate (17).

4. An oven (1) according to any one of Claims 1 to 3, characterized by the fins (16) each having an angle of 0 degrees with respect to the plate (17) when in the closed position and an angle with respect to the plate of 180 degrees when in the open position.

5. An oven (1) according to any of Claims 1 to 4, characterized by at least one hinge (7.6) which is positioned at at least one lower edge of the door (7) and which aligns with the lower side of at least one of the side walls (2, 3) and which triggers the fins (16) so as to enable the same from shifting from the open position to the closed position or from the closed position to the open position; and a hinge system (20) which can move forwards and backwards on the lower side of at least one of the side walls (2, 3).

6. An oven (1) according to Claim 5, characterized by the hinge (7.6) which is disposed at the lower edge of the door (7) aligning with the lower side of the first side wall (2) or at the lower edge of the door (7) aligning with the lower side of the second side wall (3) or at both lower edges of the door (7); and a hinge system (20) which is connected to said hinge (7.6) and which can move forwards and backwards on the lower side of the first side wall (2) or on the lower side of the second side wall (3) or on the lower side of both side walls (2, 3).

7. An oven (1) according to any one of Claims 1 to 4, characterized by at least one sensor (21) disposed in the oven compartment (11) and measures the humidity in the oven (1), a control panel (7.1) having a display (7.3) which has automatic menus for enabling the user to select the type of foodstuff to be cooked and also enabling the user to enter a cooking temperature and cooking time and at least one circuit board (7.4) which adjusts an air flow according to the information received from the sensor (21), at least one motor (9) which moves the fins (16) to bring the same to a certain position according to the information received from said electronic card (7.4), and at least two fins (16) which are activated by being triggered by the motor (9).

8. An oven (1) comprising an oven compartment (11) defined by the side walls (2, 3), a rear wall (4), an upper wall (5), a lower wall (6) and a door (7), at least one fan (8) positioned on the rear wall (4), a circular heater disposed around the fan (8) and at least one motor (9) and a lower plate (14) which is provided on the lower wall (6); and a plurality of jet nozzles (15) which are arranged on said lower plate (14), characterized by a sheet (19) which is disposed under the lower plate (14) and which has holes (19.1) as many as the number of jet nozzles (15) on the lower plate (14) and with the diameter equal to that of the jet nozzles (15), which are positioned so as to align with the bottom side of each jet nozzle (15) wherein the sheet (19) has at least one connection component (19.2) which is positioned at at least one edge of the sheet (19) so as to trigger the sheet (19) to enable the sheet (19) to move forwards and backwards; and at least one hinge (7.6) which is connected to the at least one connection component (19.2) and which is positioned at at least one lower edge of the door (7).

9. An oven (1) according to Claim 8, characterized by the holes (19.1) of the sheet (19) having the same dimensions or different dimensions according to the diameter of the jet nozzles (15).

10. An oven (1) according to Claim 8 or 9, characterized by a hidden tray (18) which is disposed under the sheet (19) and which collects the liquids that may flow from the holes (19.1).