WO2022139712A1

WO2022139712A1 - Oven with multiple fans and control method thereof

Info

Publication number: WO2022139712A1
Application number: PCT/TR2021/050056
Authority: WO
Inventors: Mehmet Baris Gocer; Erdem EROGLU; Ethem TEKE
Original assignee: Femas Metal San. Ve Tic. A. S.
Priority date: 2020-12-03
Filing date: 2021-01-22
Publication date: 2022-06-30
Also published as: EP4271943A1; TR202019677A2

Abstract

The invention relates to an oven comprising a muffle (20) confining a cooking chamber with two opposing lateral walls (23), an upper wall (21) and an opposite lower wall (27) a partition wall (28) provided therebetween; a blower (30) provided behind the partition wall (28), and a control unit (10) connected to a motor (33) of the blower (30) with rotatably arranged multiple blades (31) so as to drive in a cooking mode. The oven further comprises a first air blow opening (22) provided on the partition wall (28) and allowing transfer of hot air from the blower (30), and a second air blow opening (24) having a second center (m₂) aligned asymmetrically with respect the horizontal axis (x) passing through an imaginary a first center (m₁) in the middle of the first air blow opening (22) and disposed at a distance at the horizontal axis (x) from the first air blow opening (22).

Description

OVEN WITH MULTIPLE FANS AND CONTROL METHOD THEREOF

TECHNICAL FIELD

The invention relates to an oven equipped with multiple fans for air circulation in a cavity during the cooking operation and control method thereof.

PRIOR ART

One or more hot air circulation fan is provided in a cavity delimiting a cooking chamber to increase the heat transfer efficiency of electric heaters in cooking operation in baking ovens. The air circulation fan, which is in the structure of an axial fan, spreads the heat provided by the electric heaters adapted to the cavity to the food products on the tray disposed in the cooking chamber allowing heat transfer by forced convection.

Electric heaters are mounted on a base and/or top of the cavity. Additionally, electric heater in a ring structure is adapted to the cavity back wall surrounding the air circulation fan. The hot air in the oven with air circulation fan is discharged through multiple openings, ensuring a uniform air flow on the tray. However, ensuring uniform air distribution on the tray is a major design challenge, as the airflow generated by the axial blown fans discharged tangential from the impeller blades. Air flows in the cavity create turbulence by colliding with the inner wall of the cooking chamber and each other. Turbulence causes uneven cooking of food products placed in the muffle on a tray or grill. Therefore, the consequent chaotic result makes it difficult to predict the design parameters for a uniform air flow.

EP1780471 B1 discloses a cooking chamber to cook food therein, a driving fan arranged at a wall of the cooking chamber, and one or more driven fans arranged on a circumference of the driving fan, wherein the driving fan is connected with the drive motor which is installed at an outside of the rear wall of the cooking chamber, to rotate in accordance with an operation of the drive motor, and the driven fans are supported at the rear wall of the cooking chamber by use of bearing members, respectively, to rotate by air streams generated when the driving fan rotates. The driving fan is located at a center of a rear wall of the cooking chamber, and the driven fans can be spaced apart from the driving fan by a predetermined distance. BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to provide homogeneous hot air distribution on the baking tray in ovens with more than one blowing fan.

In order to achieve the said objective, the invention is an oven comprising a muffle confining a cooking chamber with two opposing lateral walls, an upper wall and an opposite lower wall, a partition wall provided therebetween; a blower provided behind the partition wall and a control unit connected to a motor of the blower with rotatably arranged multiple blades so as to drive in a cooking mode. The oven further comprising a first air blow opening provided on the partition wall and allowing transfer of hot air from the blower, and a second air blow opening having a second center aligned asymmetrically with respect the horizontal axis passing through an imaginary a first center in the middle of the first air blow opening and disposed at a distance at the horizontal axis from the first air blow opening. It has been observed that the second fan, which has an asymmetrical alignment with respect to the horizontal axis passing through the first center, which is the geometric center of the first air blow opening, contributes to the homogeneous distribution of hot air in the cavity. Asymmetrical alignment refers to an unequal placement of the second air blow opening in the plate. The second air blow opening can be either partially above or below the horizontal axis, or it can be formed completely away from the horizontal axis so that it does not cross it. The first air blow opening and the second air blow opening are provided at a distance from each other on the horizontal axis. In a possible embodiment, the first air blow opening and the second air blow opening may partially overlap or are preferably in the form of completely independent holes.

In a preferred embodiment, the blower has a corresponding first fan and a second fan adapted behind the partition wall such that transmitting hot air directly to the corresponding first air blow opening and the second air blow opening. In this way, each air blow opening comprises dedicated motor and fan containing blades, and it is possible to blow air from the selected opening only by the control unit selectively activating the relevant fan motor. Thus, the control of blowing hot air inside the muffle is simplified.

In a preferred embodiment, the first fan and the second fan are in the axial fan structure. The axial fan occupies a small space behind the partition wall and is resistant to cooking temperatures, making it possible to perform the cooking operation. A preferred embodiment of the invention a third air blow opening having an imaginary third center provided the partition wall asymmetrically in the horizontal axis against the first air blow opening and the second air blow opening. In this way, blower is having a second and third air blow openings provided at the either side of the first air blow opening on the horizontal axis, and therefore first, second and third air blow opening apertures arrayed on or near a slope line in the partition wall. It has been monitored that this allocation enables the hot air conveyed by the blower to show laminar flow in the muffle.

In a preferred embodiment, blower is having a corresponding third fan adapted behind the partition wall so as to provide direct hot air transmission to the third air blow opening. In this way, each opening of the blower assembly is equipped with a corresponding fan of its own. Control unit to is able to operate each air blow opening jointly or independently in the blower.

In a preferred embodiment, the third center is substantially aligned on a center axis crossing between the first center and the second center. Alignment can be interpreted as being located directly on the center axis, as well as small deviations at acute angles are included in this expression. The center axis ensures that the blower is arranged with a declination on the partition wall. This facilitates the distribution of hot air in the muffle both horizontally and vertically.

In a preferred embodiment, the blower is adjusted to rotate the blown air, and a deviation angle between the central axis with the horizontal axis is set essentially perpendicular to the tangential component of the outlet air. It has been observed that such an embodiment improves the laminar hot air distribution during baking, especially in the muffle containing a partition wall with a blower structure that rotates the blades of the motor in the blower and extracts the hot air from the opening in a rotary manner.

In a preferred embodiment, the second air blow opening and the third air blow opening are at a vicinity of both the first air blow opening on the one hand, and to the corresponding lateral wall on the other. In this way, the homogeneity of the air distribution of the blower in the transverse direction is improved.

In a preferred embodiment, the third fan is in the form of an axial fan. In this case, with the third fan, the third air blow opening is controlled independently with the control unit and a compact blower is obtained. Preferably, the third fan is arranged to rotate in the same direction as the first and second fans. In an alternative embodiment, it is possible to obtain configurations where each fan rotates in different directions. In a preferred embodiment, the first, second and third air blow openings are a circular through hole cut-out from the partition wall, and the corresponding air blow openings of the first, second and third centers, respectively, are set as the radial center. Circular air blow openings provide radial outward distribution of air from the partition wall into the muffle.

In a preferred embodiment, the first, second and third air blow openings are in a grid structure. The grill structure not only allows the passage of hot air, but also largely prevents the access of oil or similar foreign substances splashing from the oven to the blower.

In a preferred embodiment, the first air blow opening is arranged close to the upper wall and the third air blow opening is close to the lower wall. In this way, homogeneous air distribution is improved both above and below a tray or grill that is provided in the muffle transversely. In a preferred embodiment, only the first air blow opening, the second air blow opening and the third air blow opening are disposed in the partition wall. Three air blow openings are placed in the muffle, one in the center, and the others in an asymmetrical arrangement accordingly, and a homogeneous distribution of hot air is obtained in the muffle.

A preferred embodiment of the invention includes a holding element is provided on one lateral wall of the muffle in opposite directions extending through the horizontal axis such that removably secure a baking tray by separating the muffle transversely extending from length to length. The holder part may be a rib structure on the lateral wall of the muffle or a telescopic carrier structure attached to it with mounting elements. With the tray lying on the horizontal axis, homogeneous hot air distribution is optimized for a food cooked on the tray.

In a preferred embodiment, the first air blow opening is arranged in the middle of the partition wall. In this way, it is possible to circulate hot air in all directions inside the muffle with the first air blow opening. The second air blow opening, on the other hand, helps to obtain a homogeneous air flow by creating asymmetrical air movement by compensating the movement of the hot air moving in all directions from the first air blow opening, especially in the rotary direction.

In order to achieve the aforementioned objective, a preferred embodiment of the invention includes the control method for an oven described above. The control method includes the process step of driving a predetermined motor to operate an active blower selected from the group consisting of the first fan, the second fan and the third fan in a cooking operation when the cooking mode is enabled. Regardless of which fan is activated by the control unit a vacuum concurs, allowing air to enter from neighboring air blow openings. Thus, even in a cooking mode where only one fan operates, additional air inlets occur from the partition wall and the homogeneity of the hot air is improved.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a front view of a representative embodiment of the oven according to the subject matter of the invention.

Figure 2 is the schematic representation of the hot air distribution in the muffle of the oven given in Figure 1 , wherein a cooking operation with all fans are activated, right and left single fan is activated and middle fan is activated, respectively.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed explanation, the subject matter invention is explained without any limitation and only with reference to examples to better explain the subject.

A 90 cm wide oven is shown from the front in the open position in Figure 1. The oven comprises a muffle (20) with a rim on a housing (1). The muffle (20) is covered in the housing (1) by a hinged door (2) with air exhaust outlets (not shown). The muffle (20) has a planar lower wall (27) delimiting a cooking chamber and a parallel upper wall (21 ), and lateral walls (23) covering them from the sides. In the rear part of the muffle (20) opposite the rim, a flat partition wall (28) from end to end is provided. A first air blow opening (22) is formed in the middle of the partition wall (28) in the form of a circular hole. A first center (m-i) with the first air blow opening (22) is the radial center is also the geometric center of the partition wall (28). A holder part (25) is formed on the lateral walls (23) in the form of protrusions opposite to each other. A tray (40) from its outer edge is disposed on the holding element (25) on a horizontal axis (x). The horizontal axis (x) is an imaginary axis and also passes through the first center (m-i). A second air blow opening (24) is in the same shape with the first blow opening (22) and is cut-out on the partition wall (28) in close proximity to a lateral wall (23). A second center (m2), which is the radial center of the second air blow opening (24) passes through a center axis (m) which together with the first center (m-i) makes a incline angle (a) with the horizontal axis (x). The second air blow opening (24) is aligned at the top on the horizontal axis (x) with respect to the first air blow opening (22). A third air blow opening (26) is in the same shape with both the first and second air blow openings (22, 24) and is disposed in the partition wall (28) adjacent the first air blow opening (22) to be on the opposite side from the second air blow opening (24). A third center (m3), which is the radial center of the third air blow opening (26) is located on the center axis (m) together with the first and second centers (mi, m2). In this way, the third air blow opening (26) remains below the first air blow opening (22) on the horizontal axis (x). All three air blow openings (22, 24, 26) are in a grid structure, which is formed by arranging the openings extending towards the center in the radial direction and allowing air passage between them. The flat tray (40) extends end to end between the lateral walls (23) of the muffle (20) dividing the cooking chamber. Food products are placed on the tray (40). When the tray (40) is viewed from a front section (42), it cuts the circular first air blow opening (22) from its middle approximately, the second air blow opening (24) from its upper part, and the third air blow opening (26) from its lower part.

A blower (30) comprises a motor (33) for the axial fan and radial blades (31) secured on the rotating shaft of each motor (33). A first fan (32) is connected to the first air blow opening (22), a second fan (34) to the second air blow opening (24) and a third fan (36) to the third air blow opening (26) of the partition wall (28) wherein each fan of the blower (30) is identical to each other and provided behind the partition wall (28). In this way, the first fan (32) rotates the motor (33) corresponding to the first air blow opening (22), the second fan (34) the second air blow opening (24) and the third air blow opening (36) to the third air blow opening (26) over with blades (31 ) in a rotary manner to directly supply air. The motor (33) is driven by a connected control unit (10) in a printed circuit structure provided behind a control panel (3) on the oven housing (1) over an electrical cable. The control unit (10) includes a central processor (12). The operating mode of the oven is selected by the user with the help of an adjustment element (4) on the control panel (3). Accordingly, the processor (12) selects and runs the cooking algorithm from a memory module on the control unit (10). The control unit (10) operates the first fan (32), the second fan (34) and/or the third fan (36) together or in different combinations according to the cooking algorithm. In this case, the control unit (10) simply supplies the relevant motor (33) with electricity and causes the blade (31) to be rotated. The blade (31 ) rotates clockwise when viewed from the muffle (20) from the opposite side. The central axis (m) has a 30-degree incline angle (a) to the left when viewed from the opposite side of the muffle (20) so as to form a component perpendicular to the tangential flow produced by the wing (31 ) component rotating clockwise. Thus, regardless of the configuration of the blower (30), the resistance against the tangential component is formed by the effect of the hot air supplied from the openings adjacent to the air blow opening (22, 24, 26) corresponding to the active fan (32, 34, 36) and the air distribution forced into the muffle (20) becomes homogeneous. This is illustrated in the heat dissipation graphs in Figure 2. In the graph in the left-hand direction, the blower (30) actively operates all the fans (32, 34, 36). Thus, the hot air blown by rotating clockwise by the first air blow opening (22) is distributed on the tray (40) at a temperature that provides active cooking. Meanwhile, the air flow exiting the adjacent second air blow opening (24) and rotating in the same direction and the air flow exiting the third air blow opening (26) and rotating in the same direction form an interference pattern, preventing the formation of turbulence. In this way, the hot air flow over the tray (40) is substantially laminar. In the second graph in the right-hand direction, the second fan (34) and the third fan (36) are active. In this case, the corresponding second air blow opening (24) and third air blow openings (26) are rotating in the same direction to inject air. However, although the first fan (32) does not operate due to the negative pressure created, air also enters through the first air blow opening (22). Thus, although it is not as homogeneous as the activation of all fans (32, 34, 36), a double-sided air flow is created and a distribution of hot air condensed in the direction of the arrow and suitable for cooking is obtained. In the graphic below, only the first fan (32) is operating. In this case, the second air blow opening (24) adjacent to the first air blow opening (22) and the third air blow opening (26) supply air to the muffle (20) with the negative pressure formed. Although passive areas are formed as a result of the interference of this air with the accelerated air transmitted from the first air blow opening (22), an improved homogeneous air distribution is obtained compared to a muffle with a single air inlet.

REFERENCE NUMBERS

1 Housing 30 Blower

2 Door 31 Blade

3 Control panel 32 First fan

4 Adjustment element 33 Motor

10 Control unit 34 Second fan

12 Processor 36 Third fan

20 Muffle 40 T ray

21 Upper wall 42 Front section

22 First air blow opening x Horizontal axis

23 Lateral wall mi First center

24 Second air blow opening m? Second center

25 Holding element m3 Third center

26 Third air blow opening m Center axis

27 Lower wall a Incline angle

28 Partition wall

Claims

8

1- An oven comprising a muffle (20) confining a cooking chamber with two opposing lateral walls (23), an upper wall (21 ) and an opposite lower wall (27) a partition wall (28) provided therebetween; a blower (30) provided behind the partition wall (28), and a control unit (10) connected to a motor (33) of the blower (30) with rotatably arranged multiple blades (31) so as to drive in a cooking mode characterized in that a first air blow opening (22) provided on the partition wall (28) and allowing transfer of hot air from the blower (30), and a second air blow opening (24) having a second center (m?) aligned asymmetrically with respect the horizontal axis (x) passing through an imaginary a first center (m-i) in the middle of the first air blow opening (22) and disposed at a distance at the horizontal axis (x) from the first air blow opening (22).

2- An oven according to claim 1 , wherein the blower (30) has a corresponding first fan (32) and a second fan (34) adapted behind the partition wall (28) such that transmitting hot air directly to the corresponding first air blow opening (22) and the second air blow opening (24).

3- An oven according to claim 2, wherein the first fan (32) and the second fan (34) are in the form of an axial fan.

4- An oven according to any one of the preceding claims, wherein a third air blow opening

(23) having an imaginary third center (m3) provided the partition wall (28) asymmetrically in the horizontal axis (x) against the first air blow opening (22) and the second air blow opening

(24).

5- An oven according to claim 4, wherein the blower (30) is having a corresponding third fan (36) adapted behind the partition wall (28) so as to provide direct hot air transmission to the third air blow opening (26).

6- An oven according to claim 5, wherein the third center (m3) is substantially aligned on a center axis (m) crossing between the first center (ml ) and the second center (m2).

7- An oven according to claim 6, wherein the blower (30) is adjusted to rotate the blown air, and a deviation angle (a) between the central axis (m) with the horizontal axis (x) is set essentially perpendicular to the tangential component of the outlet air. 9

8- An oven according to claims 4-7, wherein the second air blow opening (24) and the third air blow opening (26) are at a vicinity of both the first air blow opening (22) on the one hand, and to the corresponding lateral wall (23) on the other.

9- An oven according to claims 4-8, wherein the third fan (36) is in the form of an axial fan.

10- An oven according to claims 4-9, wherein the first, second and third air blow openings (22, 24, 26) are in the form of a circular hole cut-out the partition wall (28), and the first, second and third center (mi, m2, m3) are set at the radial centers of the corresponding air blow openings (22, 24, 26).

11- An oven according to claim 10, wherein the first, second and third air blow openings (22, 24, 26) are in the form of a grid.

12- An oven according to claims 4-11 , wherein the first air blow opening (22) is arranged close to the upper wall (21 ) and the third air blow opening (26) is arranged close to the lower wall (27).

13- An oven according to any one of the preceding claims, wherein a holding element (25) is provided on one lateral wall (23) of the muffle (20) in opposite directions extending through the horizontal axis (x) such that removably secure a baking tray (40) by separating the muffle (20) transversely extending from length to length.

14- An oven according to any one of the preceding claims, wherein the first air blow opening (22) is arranged in the middle of the partition wall (28).

15- A control method for an oven according to claims 4-11 , comprising the process step of driving a predetermined motor (33) to operate an active blower (30) selected from the group consisting of the first fan (32), the second fan (34) and the third fan (36) in a cooking operation when the cooking mode is enabled.