A cooled induction HOB with an air acceleration device

Abstract

The invention relates to an induction hob comprising a housing (10) with a ventilation opening (14); an induction first heating element (20) and a second heating element (40) mounted spaced apart within the housing (10); a fan (50) located under the first heating element (20), which cools the first heating element (20) via a first air flow path (f1) progressing towards the first heating element (20) from the air outlet by accelerating the ambient air supplied from the ventilation opening (14); wherein the induction hob includes a fan outlet (66) in the form of a nozzle that pressurizes the air flow by forming a second air flow path (f2) at an angle with the first air flow (f1) at the fan's (50) air outlet, directing the air flow rate towards the second heating element (40); and a elevated contour (73) provided on the base plate (12) of the housing (10) that directs the cooling air progressing from the second air flow path (f2) towards under the second heating element (40) by narrowing the air flow cross-section.

Description

[0001] A COOLED INDUCTION HOB WITH AN AIR ACCELERATION DEVICE

[0002] TECHNICAL FIELD

[0003] The present invention relates to induction hobs, particularly to induction hobs that have coils cooled with the aid of a fan.

[0004] STATE OF THE ART

[0005] IGBT components used in induction hobs are exposed to high currents and voltages during power switching operations. This causes energy losses due to their electrical resistance and leads to heating. Heating can affect the performance of IGBT components and may even cause serious malfunctions in case of overheating. Therefore, effective cooling of IGBT components is necessary. Ferrite materials are used in the coils that form the basic principle of induction hobs. Ferrite materials have a high ability to direct the magnetic field, and they exhibit this property up to a certain temperature (up to the saturation temperature). As a result, reaching the saturation temperature of these materials negatively affects the operation of the system. Therefore, the coils in hobs need to be cooled. Increasing the air flow rate to the coil will prevent the ferrite material from reaching its saturation temperature. Thus, the ferrite material does not exceed its operating temperature before reaching the saturation temperature, and undesirable changes in its magnetic properties do not occur. This increases the lifespan and performance of induction hobs.

[0006] Cooling fans are used in induction hobs to provide direct air flow to the coils and IGBT components. Axial fans are generally preferred. Axial fans provide parallel air flow, creating air movement in a large volume, and they generally move air by pushing it in a single direction. This is a factor that limits our ability to direct the fan’s air flow as desired.

[0007] WO2021112776A1 relates to an induction hob with a cooling device, comprising a housing; an induction element connected to an electronic device located at the base of the housing; and a magnetically permeable planar upper plate that covers the housing, limiting an air channel with a predetermined channel height within a magnetic field distance that provides the cooking effect between the induction element and the upper plate. The induction hob includes an axial fan located at the base of the housing, which, when energized, is arranged to distribute the air flow path created in the air channel towards the induction element by directly striking the upper plate from a lower wall due to its rotational speed.

[0008] BRIEF DESCRIPTION OF THE INVENTION

[0009] The object of the invention is to ensure that the cooling air of an induction hob reaches two heating elements with a single fan.

[0010] In order to achieve the aforementioned objective, the invention relates to an induction hob comprising a housing with a ventilation opening; an induction first heating element and a second heating element mounted spaced apart within the housing; a fan located under the first heating element, which cools the first heating element via a first air flow path progressing towards the first heating element from the air outlet by accelerating the ambient air supplied from the ventilation opening. The induction hob includes a fan outlet in the form of a nozzle that pressurizes the air flow by forming a second air flow path at an angle with the first air flow at the fan’s air outlet, directing the air flow rate towards the second heating element. An elevated contour is provided on the base plate of the housing that directs the cooling air progressing from the second air flow path towards under the second heating element by narrowing the air flow cross-section. Since the air flow cross-section is narrowed, the air accelerates and reaches the second heating element from the second air flow path. In this way, both the nearby first heating element and the distant second heating element can be cooled with the flow rate produced by a single fan. By accelerating the air, the divided flow reaches the second heating element despite the falling pressure.

[0011] Preferably, the fan is an axial fan, and the ventilation opening is provided on the base plate of the housing so that it remains under the air inlet of the axial fan. In this way, the ambient air drawn from the housing base is delivered to the first heating element by the shortest path with minimal pressure loss, cooling the coil. In this case, a portion of the cooling air can be accelerated and delivered to the second heating element.

[0012] Preferably, the elevated contour is in the form of a dome that provides a third air flow path from the base plate towards the second heating element. In this case, the dome allows the air to progress over the housing base in the transverse direction and to rise towards the coil, including a vertical component. Preferably, the fan outlet includes a reducer portion that narrows to accelerate the air directed by the fan. The reducer ensures that the fan outlet narrows in the form of a nozzle, accelerating the air flow.

[0013] Preferably, a diffuser element is positioned in the second air flow path to distribute the second air flow under the second heating element. In this way, the second heating element can be cooled uniformly.

[0014] Preferably, the elevated contour is provided adjacent to an inlet portion of the diffuser element near the second heating element. In this way, the cooling air progressing in the second air flow path is accelerated along the underside of the second heating element.

[0015] Preferably, the diffuser element includes angled fins arranged to expand from an inlet portion towards the center of the second heating element. The fins allow the cooling air to be distributed radially to the circular coil.

[0016] Preferably, the diffuser element includes a base plate provided spaced under the second heater and on which the fins are provided. The base plate forms a corridor where the air in the second air flow path can progress under the second heating element without encountering any obstacles and without pressure loss.

[0017] Preferably, the base plate is made from a monoblock plastic injection provided at the inlet portion of the elevated contour. In this way, the part can be easily produced and modularly placed in the induction hob housing for dual heating element groups.

[0018] Preferably, the fan outlet extends adjacent and parallel to the side edge of the housing aligned with the elevated contour. In this way, the cooling air progressing linearly from the fan outlet crosses the distance in the transverse direction and accesses the second heating element by the shortest path.

[0019] Preferably, a heat sink extends between the first and second heating elements, adjusted adjacent to the fan outlet from a front wall and to the elevated contour from a rear wall, guiding the second air flow path.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective assembly view of the representative construction of the induction hob with an axial fan according to the invention.

[0021] Figure 2 is an exploded view of the induction hob shown in Figure 1 with the axial fan disassembled.

[0022] Figure 3 is a cross-sectional view along the direction indicated in Figure 4 of a representative application of the induction hob.

[0023] Figure 4 is a top view of the induction hob with the axial fan mounted.

[0024] DETAILED DESCRIPTION OF THE INVENTION

[0025] In this detailed description, the development subject to the invention is described with references to examples, solely to better explain the subject without any limitation.

[0026] In Figure 1 , a representative construction of the induction hob according to the invention is shown in perspective with an open-top metal tray-shaped housing (10) with its ceramic glass top plate removed. In the housing (10) of the induction hob, there is a first heating element (20) and a second heating element (40) controlled by a single circuit board (80). The housing (10) has a flat and planar base plate (12) and flat strip-shaped side edges (11 ) surrounding the perimeter of the base plate (12) perpendicularly. The top plate (not shown) is placed flatly on top of the side edges (11 ). The first and second heating elements (20, 40) have the same structure and provide heating by induction. For this purpose, the first heating element and the second heating element (20, 40) include respective flat first coil (24) and second coil (44), which are wound in interleaved hexagonal rings. The first and second coils (24, 44) are fixed at a distance from each other to the base plate (12) with circular frames (22, 42) on which they are mounted. The electronic circuit board (80) extends under the frames (22, 42). An IGBT circuit that generates high heat is located on the upper wall of the circuit board (80). A prismatic heat sink (30) made of aluminum is placed in a way that it provides heat conduction, extending between the frames (22, 42) on the upper wall (82) of the circuit board (80), close to the side edge (11 ) of the base plate (12).

[0027] In Figure 2, the components on the induction hob are shown exploded. A ventilation opening (14) is provided on the base plate (12) of the housing (10) concentric with the center of the first coil (24) adjacent to the corner. The ventilation opening (14) is in the form of a circular grille and allows the external ambient air to pass into the housing (10). A fan housing (60) sits on the base plate (12) concentrically with the ventilation opening (14) via a circular side wall (62). The fan housing (60) has a deflector plate (64) on the side wall (62) that covers half of the fan outlet surrounded by the upper edge of the side wall (62). The deflector plate (64), together with the side wall (62) in the form of a circular strip, forms a structure similar to a radial fan casing with a partially open top surface. On the side of the side wall (62) facing the second heating element (40), an extension with a partially rectangular cross-section is made to form a nozzle-shaped fan outlet (66). The fan outlet (66) is connected via a flat bridge element (68) facing the inlet (72) of an opposing diffuser element (70). The diffuser element (70) and the fan housing (60) are produced as a monoblock by plastic injection molding. An aluminum monoblock heat sink (30) extending along its length is mounted on the bridge element (68) and has a rectangular prismatic structure. The heat sink (30) is adjacent to the fan outlet (66) at one end and to the inlet (72) of the diffuser element (70) at the other end.

[0028] An impeller (56) mounted on its rotation axis is placed together with a motor (54) to the side wall (62) of the fan housing (60). The motor (54) and the impeller (56) rotatably connected to it are fixed at their center to a mounting bracket (52) in the form of a plastic bridge. The mounting bracket (52) is locked onto the upper edge of the side wall (62) from its opposite ends. When the axial fan (50) is mounted on the fan housing (60), its impeller (56) rotates and creates low pressure at the ventilation opening (14), drawing external ambient air into the housing (10). Since the rotation axis of the axial fan (50) is perpendicular to the base plate (12), the ambient air passes through the axial fan (50) and reaches the first heating element (20) directly from the open part of the side wall (62).

[0029] The diffuser element (70) has a base plate (74) similar to a truncated circle with raised peripheral edges (75). The base plate (74) extends at a distance under the coil (44) of the second heating element (40), forming an air passage corridor.

[0030] The fan housing (60) is in the form of a radial fan casing with a half-circle cut from the top, providing the axial fan (50) outlet. Next to the axial air flow path (f1 ) perpendicular to the base plate (12) above the axial fan (50), the pressurized air is radially discharged in the part covered by the deflector plate (64) through the nozzle-shaped fan outlet (66), providing an air flow in the direction of the second air flow path (f2). The second air flow path (f2) is adjacent and parallel to the side edge (11 ) of the housing (10). When the pressurized air is discharged from the fan outlet (66), it passes over the bridge element (68) and is taken into the diffuser element (70) having an inlet (72) of equal width to the fan outlet (66), passing through a elevated contour (73) and gaining an upward velocity vector. As shown in Figure 4, the air passing through the elevated contour (73) is passed between angled fins (a-e) that are adjacent and expanding, and distributed over the flat and planar base plate (74) to form a largely homogeneous and laminar third air flow path (f3). When the axial fan (50) is operated, the motor (54) attached to the mounting bracket (52) rotates the impeller (56) in the direction perpendicular to the base plate (12), and the air drawn from the ventilation opening (14) passes through the open part of the side wall (62) of the fan housing (60) directly towards the first heating element (20), cooling the first coil (24) on the frame (22). In the part covered by the deflector plate (64) on the side wall (62), the air pressure increases in the enclosed volume formed with the adjacent side wall (62) portion, and is radially discharged from the fan outlet (66). The air flow in the blowing direction of the axial fan (50) forms the first air flow path (f1 ), and the radial air flow forms the second air flow path (f2) perpendicular to the first air flow path (f1). The air discharged from the fan outlet (66) follows the second air flow path (f2) and passes over the heat sink (30) from a front wall (31 ) adjacent to the fan outlet (66) to a rear wall (33) at the opposite end.

[0031] The heat sink (30) is a monoblock aluminum extrusion profile similar to a rectangle and extends along its length with a first and a second tunnel (32, 34) parallel to each other. The first tunnel (32) is obtained by bending an upper flat outer edge (37) adjacent and parallel to the side edge (11) of the housing (10) to form a W-like cross-sectional shape. Continuing from this, a second tunnel (34) with an inverted W-shaped cross-sectional form is located.

[0032] An inner edge (36) opposite to the outer edge (37) has an inward-facing channel along its length. Additionally, the upward-facing surface of the second tunnel (34) has a downward inclined extension (35). It has been determined that the described profile of the heat sink (30) effectively cools the heat sink (30) with the cooling air progressing in the second air flow direction, and does not disturb the flow profile during this time. The rear wall (33) of the heat sink (30) abuts the inlet (72) of the diffuser element (70). Indeed, each vertical edge of the profile of the first and second tunnels (32, 34) abuts a corresponding fin (b-e) placed at the inlet (72). As shown in Figure 4, the gaps in the expanding parts of the fins (a-e) distribute the third air flow path (f3) along the inlet of the base plate (74) by widening it.

[0033] In Figure 3, the induction hob is shown with a transverse cross-section taken. In the part where the fan housing (60) is located near an upper edge of the housing (10), the part where the air flow created by the axial fan (50) is radially directed with the help of the deflector plate (64) defines the first air flow cross-sectional area (A1 ). The base plate (12) is bent upwards with a bent portion (16) and correspondingly with a reducer portion (63) in the fan housing (60), defining a narrower second air flow cross-sectional area (A2) from the first air flow cross-sectional area (A1 ) towards the nozzle-shaped fan outlet (66). Due to the reduction in cross-sectional area (A1 > A2), the cooling air at the fan outlet (66) is accelerated. The accelerated cooling air reaches the heat sink (30) from a rear wall (33), progressing linearly through the first and second tunnels (32, 34) and reaches the inlet (72) of the diffuser element (70) from a front wall (31). Here, the elevated contour (73) directs the cooling air in the second air flow path (f2), which progresses perpendicular from the upper edge to the lower edge, upwards with an incline towards under the coil (44) of the second heating element (40), parallel to the base plate (12) of the housing (10).

[0034] Meanwhile, the cooling air is compressed between the second coil (44) and the rising base plate (74), progressing through a corridor defining a third air flow cross-sectional area (A3) narrower than the second air flow cross-sectional area (A2). Due to the cross-sectional reduction (A2 > A3), the air accelerates, and while expanding radially between the fins (a-e), the pressure loss occurring is compensated, and the cooling air exits upwards through the second coil (44) via the third air flow path (f3) in a way that completely cools the second coil (44).

[0035] In Figure 4, the induction hob is shown from above. As seen here, the axial fan (50) that cools the first coil (24) of the first heating element (20) is partially blocked in the axial direction by the deflector plate (64), so the air is divided into both the axial first air flow path (f1 ) and the radial second air flow path (f2). The divided cooling air, which has undergone pressure loss, easily reaches the first coil (24) since it is close, and is delivered to the second coil (44) by being accelerated due to the cross-sectional reductions (A1 > A2 > A3). In this way, effective cooling of both coils (24, 44) with a single axial fan (50) becomes possible.

[0036] REFERENCE NUMERALS

[0037] 10 Housing 40 Second heating element

[0038] 11 Side edge 42 Frame

[0039] 12 Base plate 44 Second coil

[0040] 14 Ventilation opening 50 Axial fan

[0041] 16 Bent portion 52 Mounting bracket

[0042] 17 Middle portion 54 Motor 18 Distant portion 56 Impeller

[0043] 19 Exhaust opening 60 Fan housing 0 First heating element 62 Side wall 2 Frame 63 Reducer portion

[0044] 24 First coil 64 Deflector plate

[0045] 30 Heat sink 66 Fan outlet

[0046] 31 Front wall 68 Bridge element

[0047] 32 First tunnel 70 Diffuser element

[0048] 33 Rear wall 72 Inlet

[0049] 34 Second tunnel 73 Elevated contour

[0050] 35 Inclined extension 74 Base plate

[0051] 36 Inner edge 75 Peripheral edge

[0052] 37 Outer edge a-e Fins f1 First air flow path 80 Circuit board f2 Second air flow path 82 Upper wall f3 Third air flow path A1 First air flow cross-sectional area

[0053] A2 Second air flow cross-sectional area

[0054] A3 Third air flow cross-sectional area

Claims

CLAIMS1. An induction hob comprising a housing (10) with a ventilation opening (14); an induction first heating element (20) and a second heating element (40) mounted spaced apart within the housing (10); a fan (50) located under the first heating element (20), which cools the first heating element (20) via a first air flow path (f1) progressing towards the first heating element (20) from the air outlet by accelerating the ambient air supplied from the ventilation opening (14); characterized in that the induction hob is having a fan outlet (66) in the form of a nozzle that pressurizes the air flow by forming a second air flow path (f2) at an angle with the first air flow (f1) at the fan’s (50) air outlet, directing the air flow rate towards the second heating element (40); and an elevated contour (73) provided on the base plate (12) of the housing (10) that directs the cooling air progressing from the second air flow path (f2) towards under the second heating element (40) by narrowing the air flow cross-section.

2. An induction hob according to claim 1 , wherein the fan (50) is an axial fan and the ventilation opening (14) is provided on the base plate (12) of the housing (10) so that it remains under the air inlet of the axial fan (50).

3. An induction hob according to any of the preceding claims, wherein the elevated contour (73) is in the form of a dome that provides a third air flow path (f3) from the base plate (12) towards the second heating element (40).

4. An induction hob according to any of the preceding claims, wherein the fan outlet (66) includes a reducer portion (63) that narrows to accelerate the air directed by the fan (50).

5. An induction hob according to any of the preceding claims, wherein it includes a diffuser element (70) positioned in the second air flow path (f2) to distribute the second air flow under the second heating element (40).

6. An induction hob according to any of the preceding claims, wherein the elevated contour (73) is provided adjacent to an inlet portion (72) of the diffuser element (70) near the second heating element (40).

7. An induction hob according to claims 5-6, wherein the diffuser element (70) includes angled fins (a-e) arranged to expand from an inlet portion (72) towards the center of the second heating element (40).

8. An induction hob according to claims 5-7, wherein the diffuser element (70) includes a base plate (74) provided at a distance under the second heater (40) and on which the fins (a-e) are provided.

9. An induction hob according to claim 8, wherein the base plate (74) is made from a monoblock plastic injection provided at the inlet portion of the elevated contour (73).

10. An induction hob according to any of the preceding claims, wherein the fan outlet (66) extends adjacent and parallel to the side edge (11) of the housing (10) aligned with the elevated contour (73).

11. An induction hob according to any of the preceding claims, wherein it includes a heat sink (30) extending between the first and second heating elements (20, 40), adjusted adjacent to the fan outlet (66) from a front wall (31) and to the elevated contour (73) from a rear wall (33), guiding the second air flow path (f2).

Images