WO2013064396A1

WO2013064396A1 - An induction heating cooker

Info

Publication number: WO2013064396A1
Application number: PCT/EP2012/070979
Authority: WO
Inventors: Cemalettin Kalayci
Original assignee: Arcelik Anonim Sirketi
Priority date: 2011-11-04
Filing date: 2012-10-23
Publication date: 2013-05-10
Also published as: ES2694569T3; EP2774454B1; EP2774454A1; TR201718646T4

Abstract

The present invention relates to an induction heating cooker (1) comprising an upper table (3) produced from materials such as glass or ceramic, more than one induction coil (2) disposed under the upper plate (3), providing the cooking container of ferromagnetic feature placed thereon to be heated by the magnetic field it generates, more than one circuit board (4) providing the induction coils (2) to be energized, more than one switching element (5) connected to the circuit board (4), carrying high value electric current and heating due to effect of the current it carries, a fan (6) disposed under the upper plate (3) and at least one heat sink (7) that provides the cooling of the switching elements (5) placed thereon by distributing the air blown by the fan (6).

Description

AN INDUCTION HEATING COOKER

The present invention relates to an induction heating cooker that is provided to operate in a safe manner.

The induction heating cooker functions according to the principle of heating a cast iron or steel ferromagnetic cooking container with the magnetic field effect generated by the induction coil. The energy efficiency of induction heating cookers is considerably high since the heat required for cooking is not generated in the gas or electric burners on the cooker but directly in the cooking container. In order to drive the induction coils that generate magnetic field, great amount of electric current is passed through electronic switching elements such as the IGBT (Insulated Gate Bipolar Transistor) or the diode bridge on the circuit board and therefore the said switching elements are excessively heated. An effective cooling system is required so that the switching elements can operate safely. In state of the art, the switching elements carrying high current and where the most overheating is observed are cooled by being connected to a heat sink and by delivering air thereto by means of a fan.

In order to assure that the induction heating cooker operates in safe conditions, the temperature of the switching elements must be kept under control. When the switching elements reach the critical temperature defined by the producer, the current passed therethrough is cut off by the control unit.

In the state of the art induction heating cookers, the temperature of the switching element (4’) is tried to be kept under control by connecting a sensor (2’) onto the heat sink (3’). However, since the temperatures of the switching element (4’) and the heat sink (3’) will be different from each other, an efficient and safe control mechanism cannot be provided. Since the sensor (2’) contacts onto the heat sink (3’), the temperature measured by the sensor (2’) is lower than the actual temperature of the switching element (4’). Since the turning off of cooker is decided depending on the temperature values measured by the sensor (2’), it is crucial to perform a temperature control that does not compromise from cooking efficiency and also provides safe operating conditions.

In the state of the art European Patent Application No. EP1936283, a cooking device is disclosed, comprising a guide that is disposed on the heat sink so as to cover at least some portion of the heat sink and that provides some of the cold air to be guided onto the switching elements.

The aim of the present invention is the realization of an induction heating cooker that is provided to operate in a safe manner by providing the temperature of the switching elements to be measured as close as possible to the actual values.

The induction heating cooker realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof comprises at least one heat sink whereon the switching elements are placed, providing the cooling of the switching elements, a plate produced from a heat-conducting material, placed on the heat sink so that the switching elements are therebetween, a sensor disposed on the plate and used for measuring temperature and a control unit that provides the power to be transmitted to the switching elements depending on the temperature data transmitted by the sensor. The switching elements heat due to the current passing therethrough. The heat sink provides the cooling of the switching elements by spreading the cold air blown by the fan. The plate is placed onto the switching elements so that there is heat transfer therebetween by means of conduction. Thus, when the switching elements heat, the plate heats as well. The temperature of the plate is almost equal to the average temperature of the switching elements. By means of the sensor being placed onto the plate, the sensor is provided to measure the average temperature of the switching elements. When the switching elements excessively heat, the control unit cuts off the current passing through the switching elements and prevents the switching elements from being damaged. With the control unit controlling the transmission of power to the switching elements according to the temperature data transmitted by the sensor, the induction heating cooker is provided to operate in safer operating conditions with respect to the user.

In an embodiment of the present invention, the switching elements are fastened onto the heat sink and the plate is mounted onto the switching elements so as to contact the switching elements.

In another embodiment of the present invention, the plate is placed between the sensor and the heat sink so as to prevent the contact of these two. Thus, the sensor is prevented from directly contacting the heat sink. Consequently, the sensor is enabled to measure the temperature of the plate heating up due to the heat conducted to the plate from the switching elements.

In another embodiment of the present invention, the plate is placed so as to longitudinally extend over the heat sink. Thus, the heat passing to the plate from the switching elements placed side by side onto the heat sink is provided to be homogeneously distributed on the plate.

In another embodiment of the present invention, the sensor is placed at the center of the plate so that the switching elements remain at both sides of the sensor. Thus, the heat passing from the switching elements to the plate is provided to be better homogenized. Being placed almost at the center of the plate, the sensor is provided to measure the heat effectively distributed on the plate.

In another embodiment of the present invention, more than one fixing hole is arranged on the plate. After being positioned between the heat sink and the plate, the switching elements are fastened to the heat sink by means of fixing elements. The fixing element is respectively passed through the fixing hole and the switching element to be fixed onto the heat sink. Similarly, the sensor is also positioned on the plate and fastened onto the plate by means of a fixing element. The other end of the fixing element extends towards the heat sink.

In another embodiment of the present invention, the plate is produced from rectangular sheet metal. With a much shorter width with respect to its length, the plate is in a flat rod shape.

In another embodiment of the present invention, the plate is produced from aluminum. Thus, the heat conduction feature of the plate is improved.

By means of the present invention, an induction heating cooker is realized, wherein the temperature of the switching elements are measured by means of the sensor on the plate placed onto the switching elements.

The induction heating cooker realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

Figure 1 – is the schematic view of an induction heating cooker.

Figure 2 – is the perspective view of the heat sink, the switching elements, the sensor and the plate in the state of the art.

Figure 3 – is the perspective view of a heat sink, a fan, switching elements, a sensor and a plate.

Figure 4 – is the perspective view of a heat sink, switching elements, a sensor and a plate.

Figure 5 – is the perspective view of a plate.

Figure 6 – is the partial perspective view of a heat sink, switching elements, a sensor and a plate.

Figure 7 – is the view of detail A in Figure 6.

The elements illustrated in the figures are numbered as follows:

Induction heating cooker
Induction coil
Upper plate
Circuit board
Switching element
Fan
Heat sink
Plate
Sensor
100 Fixing hole
111 Fixing element
Control unit

The induction heating cooker (1) comprises an upper table (3) produced from materials such as glass or ceramic, more than one induction coil (2) disposed under the upper plate (3), providing the cooking container of ferromagnetic feature placed thereon to be heated by the magnetic field it generates, more than one circuit board (4) providing the induction coils (2) to be energized, more than one switching element (5) connected to the circuit board (4), carrying high value electric current and heating due to effect of the current it carries, a fan (6) disposed under the upper plate (3) and at least one heat sink (7) that provides the cooling of the switching elements (5) placed thereon by distributing the air blown by the fan (6).

The switching elements (5) are elements carrying high-value electric current, overheating due to the current, such as IGBT (Insulated Gate Bipolar Transistor) and diode bridge. Being placed onto the heat sink (7) distributing the cold air blown by the fan (6), the switching elements (5) are prevented from overheating thanks to the heat transfer between the switching elements (5) and the heat sink (7).

The induction heating cooker (1) of the present invention furthermore comprises a plate (8) produced from a heat-conducting material, placed on the heat sink (7) so as to contact the switching elements (5), at least one sensor (9) disposed on the plate (8) and used for measuring the temperature of the plate (8) and a control unit (12) that controls the energizing of the switching elements (5) depending on the temperature data transmitted by the sensor (9). Since the switching elements (5) contact both the heat sink (7) and the plate (8), heat transfer occurs between the switching element (5), the heat sink (7) and the plate (8) by means of conduction. Since the plate (8) contacts every one of the switching elements (5), the temperature of the plate (8) is almost equal to the average temperature of the switching elements (5). The plate (8) undertakes the role of homogenizing the temperatures of the switching elements (5). By means of the sensor (9) being placed onto the plate (8), the sensor (9) is provided to measure the average temperature of the plate (8), hence of the switching elements (5). The control unit (12) controls the current transmitted to the switching elements (5) depending on the temperature values transmitted by the sensor (9). When the temperature value measured by the sensor (9) reaches the critical value determined by the producer, the control unit (12) cuts off the current passing through the switching elements (5). Thus, the switching elements (5) are prevented from overheating, providing safe operating conditions with respect to the user.

In an embodiment of the present invention, the switching element (5) is fastened onto the heat sink (7) so as to be between the heat sink (7) and the plate (8). The switching elements (5) contact both the heat sink (7) and the plate (8). Accordingly, when current passes through one of the switching elements (5), heat transfer occurs between that switching element (5) and the plate (8). By means of the sensor (9) on the plate (8), the temperature of the plate (8), hence of the switching element (5) is measured.

In another embodiment of the present invention, the plate (8) is placed between the sensor (9) and the heat sink (7). By means of the plate (8), the sensor (9) is prevented from directly contacting the heat sink (7). Thus, heat transfer between the sensor (9) and the heat sink (7) is prevented, and the sensor (9) is prevented from getting cold by being affected by the cold air spreading from the heat sink (7). Consequently, the sensor (9) is provided to measure the temperature of the plate (8) heating due to the heat passing from the switching elements (5) to the plate (8).

In another embodiment of the present invention, the plate (8) is longitudinally placed over the heat sink (7). Since the switching elements (5) are placed in a side-by-side manner onto the heat sink (7), the plate (8) is longitudinally placed onto the heat sink (7) so as to contact every one of the switching elements (5).

In another embodiment of the present invention, the sensor (9) is placed almost at the center of the plate (8). The sensor (9) is placed onto the plate (8) so that the switching elements (5) are at both sides of the sensor (9). Thus, the heat emanated from the switching elements (5) is provided to be homogeneously distributed over the plate (8).

In another embodiment of the present invention, the induction heating cooker (1) comprises more than one fixing hole (10, 100) arranged on the plate (8) and more than one fixing element (11, 111) that provides the switching element (5) or the sensor (9) to be fastened onto the heat sink (7) with one end being fixed to the heat sink (7) by being passed through the fixing hole (10, 100) and over the switching element (5) or the sensor (9). The switching elements (5) are placed onto the heat sink (7) and the fixing element (11) is fixed onto the heat sink (7) by being passed through the fixing hole (10) on the plate (8) and over the switching element (5). The sensor (9) is preferably in circular or semi-circular form. The sensor (9) is placed onto the fixing hole (100) on the plate (8) and the fixing element (111) is fixed onto the heat sink (7) by being passed over the sensor (9). Thus, the mounting of the sensor (9) to the plate (8) is realized.

In another embodiment of the present invention, the plate (8) is produced from rectangular sheet metal.

In another embodiment of the present invention, the plate (8) is produced from aluminum. Since the aluminum is a material with high heat conduction coefficient, the heat transfer from the switching elements (5) to the plate (8) is improved.

By means of the present invention, the average temperature of the switching elements (5) is provided to be measured by placing the sensor (9) on a plate (8) whereto heat transfer is provided from the heat sink (7) and the switching elements (5). Thus, safer operating conditions are provided for the user.

It is to be understood that the present invention is not limited by the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection postulated by the claims of the present invention.

Claims

An induction heating cooker (1) comprising an upper table (3) produced from materials such as glass or ceramic, more than one induction coil (2) disposed under the upper plate (3), providing the cooking container of ferromagnetic feature placed thereon to be heated by the magnetic field it generates, more than one circuit board (4) providing the induction coils (2) to be energized, more than one switching element (5) connected to the circuit board (4), carrying high value electric current and heating due to effect of the current it carries, a fan (6) disposed under the upper plate (3) and at least one heat sink (7) that provides the cooling of the switching elements (5) placed thereon by distributing the air blown by the fan (6).

characterized by

- a plate (8) produced from a heat-conducting material, placed on the heat sink (7) so as to contact the switching elements (5),

- at least one sensor (9) disposed on the plate (8) and used for measuring the temperature of the plate (8) and

- a control unit (12) that controls the energizing of the switching elements (5) depending on the temperature data transmitted by the sensor (9).
An induction heating cooker (1) as in Claim 1, characterized by the switching element (5) fastened onto the heat sink (7) so as to be between the heat sink (7) and the plate (8).
An induction heating cooker (1) as in Claim 1 or 2, characterized by the plate (8) placed between the sensor (9) and the heat sink (7).
An induction heating cooker (1) as in any one of the above claims, characterized by the plate (8) that is longitudinally placed on the heat sink (7).
An induction heating cooker (1) as in any one of the above Claims, characterized by the sensor (9) that is placed almost at the center of the plate (8).
An induction heating cooker (1) as in any one of the above claims, characterized by more than one fixing hole (10, 100) arranged on the plate (8) and more than one fixing element (11, 111) that provides the switching element (5) or the sensor (9) to be fastened onto the heat sink (7) with one end being fixed to the heat sink (7) by being passed through the fixing hole (10, 100) and over the switching element (5) or the sensor (9).
An induction heating cooker (1) as in any one of the above Claims, characterized by the plate (8) that is produced from rectangular sheet metal.
An induction heating cooker (1) as in any one of the above Claims, characterized by the plate (8) that is produced from aluminum material.