EP4035503A1

EP4035503A1 - Induction hob having cooling device with axial fan

Info

Publication number: EP4035503A1
Application number: EP19955192.0A
Authority: EP
Inventors: Metin OZTURK; Omer YANIK; Turgay KILIC
Original assignee: Mamur Teknoloji Sistemleri Sanayi AS
Current assignee: Mamur Teknoloji Sistemleri Sanayi AS
Priority date: 2019-11-18
Filing date: 2019-11-18
Publication date: 2022-08-03
Also published as: WO2021112776A1; EP4035503A4

Abstract

The present invention relates to an induction hob with a cooling device (40) comprising a casing (10); an induction element (50) connected to an electronic device (30) disposed on a lower sheet (12) of the casing (10); a magnetic permeable planar top plate (20) covers top of the casing (10) such that confine an air duct (18) with a predetermined channel height (H) under a magnetic field distance providing a cooking operation with the induction element (50). The cooling device (50) is having an axial fan (43) arranged on the lower sheet (12) of the casing (10) such that rotational speed create an air flow path (F) inside the air duct (18) directly hit the top plate (20) from the lower sheet (12) in order to manipulate the air through the induction element (50) when the axial fan (43) is energized.

Description

INDUCTION HOB HAVING COOLING DEVICE WITH AXIAL FAN

TECHNICAL FIELD

The present invention relates to induction hobs, in particular hobs with a cooling device for cooling induction coils and the electronic control unit by means of a fan.

BACKGROUND ART

During the cooking operation induction coils and electronic components of a circuit board of ab induction hob is heated. In such a case, radial fans are energized to cool down the circuit boards. Although the radial fan provides the desired efficiency in terms of regional cooling, it is insufficient to cool down entire components of the hobs with more than one heater.

EP2578058 discloses an induction heating cooker comprising more than one induction coil, providing the cooking container of ferromagnetic feature placed thereon to be heated by the magnetic field it generates, an upper plate disposed above the induction coils, produced from a material like glass or ceramic, more than one circuit board providing the induction coils to be energized, more than one switching element like IGBT or diode bridge connected to the circuit boards carrying high value electric current and overheated due to effect of the current and a lower plate disposed at the underside of the upper plate, whereon the circuit boards are arranged horizontally side by side at intervals, an axial type fan disposed in an opening arranged on the lower plate, and a heat sink disposed over the opening to be concentric with the fan and surrounding the fan.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to ensure that the induction heater is effectively cooled during operation in the induction hobs.

In order to achieve the aforementioned objectives, the invention comprises an induction hob with a cooling device comprising a casing; an induction element connected to an electronic device disposed on a lower sheet of the casing; a magnetic permeable planar top plate covers top of the casing such that confine an air duct with a predetermined channel height under a magnetic field distance providing a cooking operation with the induction element. The cooling device on the induction hob is having an axial fan arranged on the lower sheet of the casing such that when energized rotational speed create an air flow path inside the air duct directly hit the top plate from the lower sheet in order to manipulate the air through the induction element. In the cooking operation, heat is generated on both in the induction element and the electronic device providing functional support containing electronic components. When the axial fan operates, moves the blown air towards the top sheet, within the volume of the casing between the top sheet and the axial fan. Air hitting the top sheet from its lower sheet provides indirect cooling to the induction element that is heated during operation. In this case, cooling is performed by forced convection via cooling air transmitted from above on both the induction element and in the surrounding area. In a preferred embodiment, the top plate comprises ceramic or hardened glass. Thus, the magnetic field transition to the induction element and the upper part of the top sheet is possible and also a self-planar lower wall is formed inside the ceramic or glass table in flat panel structure, which deflects the air flow path downward.

In a preferred embodiment, the axial fan is provided beneath a heating coil of the induction element in the form of a grid wherein the air directly blown diffuses. In this case, with the axial fan, the heating coil is cooled entirely both from the bottom and the top, respectively, by means of the direct cooling air passing directly through induction coil when first blown and with the indirect cooling air reaching to the induction element by deflecting from the top sheet.

In a preferred embodiment, a baffle delimit the air duct by at least partially surrounding the axial fan in the opposite direction to the induction element. Therefore, the air duct directs more of the cooling air generated by the axial fan to the induction element and the amount of scattered air ineffective for cooling is reduced.

In a preferred embodiment, the baffle is in a plate form mounted at the lower sheet in a standing manner. The baffle is simply mounted vertically to the lower sheet and, when the axial fan operates direct the air blown in the inner chamber between the lower sheet and the top sheet to the section to the air duct section. This ensure more air delivery from the axial fan to the induction element. The baffle can be in one piece or multi-piece plate form.

In a preferred embodiment, the baffle is extending between the electronic device and a peripheral wall of the casing. Since the electronic device comprises components that dissipate heat, the air supplied from the axial fan hits the baffle and reaches both the induction element and the electronic device. In a preferred embodiment, a heat sink is provided on the electronic device defining a critical cooling area adjacent to the induction element. The heat sink helps to remove the excess heat from the electronic device by conduction, which cannot be removed by the forced convection caused by the axial fan alone. The electronic device supports the removal of heat in the critical cooling area with the highest heat dissipation in the casing, in the region where the heat sink is mounted and where the highest heat is generated in the casing during operation such as the inverter circuits.

In a preferred embodiment, the axial fan is disposed at a vicinity of a corner of casing in the rectangular form and the baffle is arranged in an elongated form such that surrounding the axial fan along outward facing edges to focus the air flow path towards the critical cooling area. In this case, the baffle allows the indirect cooling air generated by the axial fan to create an air flow path towards the critical cooling area rather than the parts facing the outer edges of the casing.

In a preferred embodiment, the baffle is having a spaced section enlarging the air duct at the adjacent section against the heat sink. This creates an expanded cooling air flow corridor next to the heat sink, so that it provides more cooling in this area.

In a preferred embodiment, the height of the baffle is adjusted to penetrate to the air duct. Thus, the baffle reaches from the lower sheet above the induction element and ensures complete direct cooling air passes through the induction element.

In a preferred embodiment, the axial fan is secured between the lower sheet and the top sheet in a vertical position. It has been observed that the vertical position provides a much more efficient cooling compared to other angles, with the direct and indirect cooling air provided by the axial fan in the cooling of the induction element.

A preferred embodiment, an air inlet is provided on the casing in fluid connection with the air duct allowing the air flow. In a possible embodiment, the air inlet is located on the peripheral wall. In fact, if the baffle extend parallel to the peripheral wall, the air inlets are positioned close to the lower sheet, preventing the air outlet from the air inlets with a turbulence created by the axial fan, allowing the creation of a counter-vacuum effect to allow the upward air circulation of the axial fan to enable continuous air supply into the casing. Also, in an embodiment where the baffle is greater than the channel height, the air inlet may extend vertically close to the height of the induction element, for example in a grid structure. In a preferred embodiment of the invention, the axial fan is connected to a wiring harness selectively for being energized by means of the electronic device. In this case, the electronic device may be programmed as desired, for example, when the threshold value on a component is exceeded or when the inner temperature of the casing rises above a reference value, it may operate the axial fan by conducting current.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a top perspective view of a representative embodiment of an induction hob with the subject matter cooling device where top plate is transparent.

Figure 2 is a front schematic illustration of a representative embodiment of the subject matter induction hob comprising an axial fan cooling device.

Figure 3 is a schematic top view of a representative embodiment of the induction hob.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the inventive development is described without any limitation and only with references to the examples for a better disclosure of the subject.

In Figure 1 , a representative embodiment of the inventive induction hob having four heating elements is shown in perspective view. A casing (10) in the form of a flat box with an open top is formed by bending the metal sheet. The flat lower sheet (12) of the casing (10) is provided with vertical peripheral walls (14), successively rising along its four circumferential edges. A top sheet (20) resting on an upper edge (16) of the peripheral walls (14) is covering the casing (10) from above delimits the inner chamber between a flat planar lower wall (22) of the casing (10) and itself. Top plate (20) is made of heat resistant glass, for example crystallized glass. On the peripheral wall (14), an air inlet (15) in grid structure consisting of multiple holes extending vertically and equidistant from each other is formed.

An electronic device (30) having a printed board (32) is disposed at the lower sheet (12) of the casing (10). The electronic device (30) in addition to the printed board (32), has an induction element (50) that is connected to the card in a current conducting manner. The induction element (50) comprises a heating coil (52) and second coil (53) provided in the electronic device (30), each of which is aligned on a flat planar upper wall (24) of the top sheet (20), under the marked area, such that an air duct (18) is remained, the height (FI) of which is defined by the distance between the top sheet (20) and them. The heating coil (52) and the second coil (53) are induction coils of similar construction and contain a ferrite from which magnetic flux is generated. Heating coil (52) has gaps that allow air to pass between arms extending radially towards a circular frame.

When the induction element (50) is energized on the printed board (32), a cooling device (40) carries the heat dissipated in both the electronic device (30) and the induction element (50), so that it reduces the heat of the components. To achieve this, the cooling device (40) comprises an axial fan (43) and an auxiliary axial fan (44) connected to the printed board (32) by a wiring harness (33). Axial fans (43, 44) are fixed on the lower sheet (12) as adjacent to two opposite ends of the electronic device (30), each coinciding with a corner in the casing (10). The axial fans (43, 44) are of the known circular frame open propeller type and the air flow to be created in operation is positioned perpendicular to the lower sheet (12). Axial fans (43, 44) face the lower sheet (12) at the bottom and the corresponding heating coils (52, 54) at the top. The baffle (41 ) in the form of a metal plate extends in a spaced manner towards the peripheral walls (14) where the axial fans (43, 44) are adjacent, and surrounds both fans (43, 44) in terms of their outward facing parts in the casing (10). The baffle (41 ) is erected by being mounted to the lower sheet (12) in an integral structure. The baffle (41 ) height is adjusted such that it passes the heating coils (52, 54), that is, it enters the air duct (18). However, the baffle (41 ) has a distance that allows air passage between the top sheet (20) and the lower wall (22). This distance is shorter than the channel height (H).

A heat sink (42) is mounted on the components generating higher heat on the printed board (32). The heat sink (42), in the embodiment shown in the figure, is made of aluminum material as a block and two heat sinks (42) are used adjacent to each other. The heat sink (42) is located close to the peripheral wall (14) on the printed board (32) which is mounted in parallel on the lower sheet (12). On the other hand, the heat sink (42) creates a high temperature zone within the casing (10) in a critical cooling area where the heating coil (54) is under. The axial fan (43) is located close to the corresponding heating coil (52) and heat sink (42). Thus, since the area in which the air flow generated by the operation of the axial fan (43) will be close to the area where the heat is the highest inside the casing (10), the heat transfer efficiency increases. The total number of cookers has been increased to 4 with a second cooking device (60) in the same structure in the casing (10) identical with the one described above.

In Figure 2, a casing (10) with the cooling device (40) is shown schematically from the front. Here, the position of the axial fans (43, 44) under the induction element (50) are seen. In the embodiment given in Figure 3, an induction heater hob is shown schematically from the top. In this view, it may be seen that the axial fans (43, 44) are partially below the corresponding heating coils (52, 54). Namely, the vertical air flow provided by the axial fan (43) continues on its way by passing through the heating coil (54) by creating a direct cooling air, and then rises along the channel height (H) and hits the lower wall (22) on the top sheet (20) reflecting back and creates an indirect cooling air reaching again the heating coil (52) from the top. The baffle (41) prevents the scattering of the air provided by the axial fan (43), and manipulate to focus especially in the critical cooling area (1) in the direct or indirect post-reflection case. As shown in both Figure 2 and Figure 3, the air flow path (F) advances from the lower sheet (12) towards the lower wall (22) forming the ceiling, and is distributed on both the electronic device (30) and the induction element (50) by reflecting therefrom. Both axial fans (43, 44) are located symmetrically to each other. As shown in Figure 3, the baffle (41) surrounds both axial fans (43, 44) from their outward facing parts and advances towards the middle, forming a spaced section (45) with respect to the printed board (32). Thus, with the operation of the axial fans (43, 44), the heat transfer, which will decrease with the low air flow in the middle, is compensated by providing a wide cooling corridor. Also, as the expanded section focuses the air flow inward from the peripheral walls (14), the air supplied by the axial fans (43, 44) is allowed to be pushed towards the printed board (32). REFERENCE NUMBERS

1 Critical cooling area 40 Cooling device 10 Casing 41 Baffle 12 Lower sheet 42 Heat sink

14 Peripheral wall 43 Axial fan

15 Air inlet 44 Auxiliary axial fan

16 Upper edge 45 Spaced section 18 Air duct 50 Induction element

20 Top plate 52 Heating coil 22 Lower wall 54 Second coil 24 Upper wall 60 Second cooking device 30 Electronic device F Air flow path

32 Circuit board H Channel height

33 Wiring harness

Claims

1. An induction hob with a cooling device (40) comprising a casing (10); an induction element (50) connected to an electronic device (30) disposed on a lower sheet (12) of the casing (10); a magnetic permeable planar top plate (20) covers top of the casing (10) such that confine an air duct (18) with a predetermined channel height (H) under a magnetic field distance providing a cooking operation with the induction element (50) characterized in that the cooling device (50) is having an axial fan (43) arranged on the lower sheet (12) of the casing (10) such that when energized rotational speed create an air flow path (F) inside the air duct (18) directly hit the top plate (20) from the lower sheet (12) in order to manipulate the air through the induction element (50).

2. An induction hob according to claim 1 , wherein the axial fan (43) is provided beneath a heating coil (52) of the induction element (50) in the form of a grid wherein the air directly blown diffuses.

3. An induction hob according to any of the preceding claims, wherein a baffle (41 ) delimit the air duct (18) by at least partially surrounding the axial fan (43) in the opposite direction to the induction element (50).

4. An induction hob according to claim 3, wherein the baffle (41 ) is in a plate form mounted at the lower sheet (12) in a standing manner.

5. An induction hob according to claims 3-4, wherein the baffle (41 ) is extending between the electronic device (30) and a peripheral wall (14) of the casing (10).

6. An induction hob according to claims 3-5, wherein a heat sink (42) is provided on the electronic device (30) defining a critical cooling area (1) adjacent to the induction element (50).

7. An induction hob according to claim 6, wherein the axial fan (43) is disposed at a vicinity of a corner of casing (10) in the rectangular form and the baffle (41) is arranged in an elongated form such that surrounding the axial fan (43) along outward facing edges to focus the air flow path (F) towards the critical cooling area (1 ).

8. An induction hob according to claims 6-7, wherein the baffle (41) is having a spaced section (45) enlarging the air duct (18) at the adjacent section against the heat sink (42).

9. An induction hob according to claims 3-8, wherein the height of the baffle (41) is adjusted to penetrate to the air duct (18).

10. An induction hob according to any of the preceding claims, wherein the axial fan (43) is secured between the lower sheet (12) and the top sheet (20) in a vertical position.

11. An induction hob according to any one of the preceding claims, wherein an air inlet (15) provided on the casing (10) in fluid connection with the air duct (18) allowing the air flow.

12. An induction hob according to any of the preceding claims, wherein the axial fan (43) is connected to a wiring harness selectively for being energized by means of the electronic device (30).

13. An induction hob according to any of the preceding claims, wherein the top plate (20) is comprising a ceramic or hardened glass.