KR20010068220A - Microwave oven for convecting heated-air - Google Patents

Abstract

PURPOSE: A microwave oven is provided to minimize a space for a heating body through integrally forming a fan and the heating body, and not to require a temperature detect circuit by forming the heating body having a temperature detect characteristic. CONSTITUTION: Hot air heated by a heating body(51) is supplied to a cooking chamber by a hot air convection instrument. Herein, the heating body containing a PTC thermistor characteristic of blocking current by sudden increase of resistance is integrally formed with a fan(40). A rotating electrode(52) connected with the heating body is installed on a rotating shaft(33) of a motor. Herein, the rotating electrode is contacted with a fixing electrode(53) for being electrically connected. The fixing electrode is connected to a main power while being stored in a store member(56). Herein, the store member is firmly installed on a support plate(34) between a rear plate and a back cover of the cooking chamber by using a connecting member(58). Moreover, the fan is formed by heat resistant material or ceramic material such as the heating body.

Description

Microwave oven for convecting heated-air

The present invention relates to a microwave oven for hot air convection, and more particularly, to a microwave oven for hot air convection in which the heating element of the heat generating means is integrally formed with the fin of the hot air convection means.

An example of this type of hot air convection microwave oven is disclosed in Korean Utility Model Application No. 96-31189 filed by Samsung Electronics Co., Ltd., filed on September 24, 1996. The microwave oven for hot air convection disclosed in this prior art is provided with hot air convection means for forcibly convection the ambient air heated by the heat generated from the heating element to the cooking chamber. By the way, the heating element and the hot air convection means are mounted separately.

Such a hot air convection microwave oven is shown schematically in FIG. 1 as a side view. Referring to FIG. 1, a door 10 is installed at a front surface of the cooking chamber 20, and a rear side of the cooking chamber 20 is coupled to a motor 30 and a rotation shaft 33 of the motor 30. 40 and a heater, which is a heating element 51, are provided adjacent to the fin 40, and below the cooking chamber 20, a rotary plate 25 on which a workpiece is placed, and the rotary plate 25. Driving means for driving is provided.

The motor 30 rotates the fin 40 together with the operation of the microwave oven, and at the same time, the heating element 51 operates to generate heat for heating the ambient air. The fan 40 blows the surrounding air into the cooking chamber 20 and sucks it out of the cooking chamber 20. Therefore, the ambient air heated by the heat of the heat generating element 51 forms hot air which is forcedly circulated by the fin 40. The hot air is blown into the cooking chamber 20 through the vent 22 formed in the rear plate 21 of the cooking chamber 20 by the fan 40 to supply heat energy necessary for cooking of the cooked product, and then the other ventilation unit. The forced convection is drawn to the outside of the cooking chamber 20 through the 23.

However, the microwave oven for hot air convection of the prior art in which the fin 40 and the heating element 51 are separately installed has the following problems.

First, hot air forced by convection by the fin 40 always generates frictional resistance with the heating element 51 and the fin 40 itself, and in particular, has a problem of large friction with the heating element 51. Therefore, as the convection speed of the hot air increases in order to promptly produce hot air convection and speed up cooking, the noise is increased while the frictional resistance of the fan 40 and the heating element 51 increases in proportion to this.

Second, there is a problem that the fin 40 and the heating element 51 should be installed at appropriate intervals in consideration of the frictional resistance of hot air. Therefore, when the fin 40 and the heat generating element 51 are too close, the installation space of the fin 40 and the heat generating element 51 decreases, but the frictional resistance of the hot air caused by the fin 40 and the heat generating element 51 is increased. . On the contrary, if the fin 40 and the heat generating element 51 are too far away, the frictional resistance of the hot air by the fin 40 and the heat generating element 51 decreases, but the convection time of the hot wind increases, which reduces the hot air convection efficiency and cooking efficiency. In addition, the installation space of the fin 40 and the heating element 51 is increased.

Third, when the temperature of the hot air forced to convection in the cooking chamber 20 rises above the temperature required for cooking of the cooked material of the cooking chamber 20, a hot air temperature sensing circuit is required to stop the operation of the heating element 51. There is this. Therefore, the installation of such a sensing circuit is a factor that increases the manufacturing cost.

Accordingly, an object of the present invention is to provide a microwave oven for hot air convection that reduces noise by reducing frictional resistance of hot air caused by a heating element during forced convection of hot air.

Another object of the present invention is to provide a microwave oven for hot air convection by minimizing the space required for installation of the heating element by integrally molding the heating element.

Still another object of the present invention is to provide a microwave oven for hot air convection, which does not require a sensing circuit for sensing the temperature of hot wind by integrally forming a heating element having a temperature sensing characteristic with a fin.

Figure 1 is a side cross-sectional view schematically showing a conventional microwave oven for hot air convection.

Figure 2 is a side cross-sectional view schematically showing a microwave oven for hot air convection according to the present invention.

3 is an enlarged view of a portion “C” of FIG. 2;

4 is a view of Z in the direction of arrow "D" of FIG.

* Description of the symbols for the main parts of the drawings *

10: door 20: cooking chamber

21: rear plate of the cooking chamber 22, 23: vent

25: rotating plate 30: motor

33: rotation axis of the motor 34: support plate

35 back cover 37 fastening member

40: 홴 51: heating element

52: rotating electrode 53: fixed electrode

In order to achieve the above object, the present invention, in the microwave oven for hot air convection having a hot air convection means for forcibly convection the ambient air heated by the heat generated from the heat generating means to the cooking chamber, the hot air convection means is a motor and And a fan coupled to the rotating shaft of the motor, wherein the heating means comprises a heating element integrally formed with the fan and a current supply means for supplying current to the heating element. to provide.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings, the same reference numerals will be given to the same components as the prior art.

Referring to FIG. 2, which shows a preferred embodiment of the present invention, a door 10 is installed at the front of the cooking chamber 20, and a motor 30 and a rotation shaft of the motor 30 are provided at the rear of the cooking chamber 20. 홴 40 coupled to the 33 and integrally formed with the heating element 51, and a current supply means for supplying current to the heating element 51, and a cooked object below the cooking chamber 20. The rotating plate 25 is positioned and drive means for driving the rotating plate 25 is provided.

The motor 30 installed at the rear of the cooking chamber 20 is firmly fixed to the back cover 35 by the fastening member 37. The rotating shaft 33 of the motor is rotatably supported by the support plate 34 provided between the back cover 35 and the rear plate 21 of the cooking chamber 20. The rotating electrode 52 is firmly fixed to the rotating shaft 33 of this motor. At least two vents 22 and 23 are formed in the rear plate 21 of the cooking chamber 20 to force convection of ambient air heated by the heating element 51.

The motor 30 fixed to the back cover 35 rotates the fin 40 supported by the support plate 34. The shock 40 is forcedly circulated by blowing air around the inside of the cooking chamber 20 and sucking it out of the cooking chamber 20. The heat generating element 51 integrally formed with the fin 40 generates heat for heating the ambient air. The heating element 51 is electrically connected to the rotating electrode 52 described above.

Referring to FIGS. 3 and 4, the heating element 51 is formed of a ceramic-based material having a temperature control characteristic such as a general ceramic-based material or a PTC thermistor having no temperature control property to generate surface heating. Generally, in the cooking chamber 20, the electromagnetic wave is emitted and the air (hot air) heated by the heating element 51 is supplied to the cooking chamber 20 by the hot air convection means while the cooked object is cooked. In this process, the temperature sensing circuit controls the temperature of the hot air in order to prevent the temperature of the hot air from rising too much to cook the cooked material of the cooking chamber 20 too much. By the way, when the heating element 51 having the PTC thermistor characteristic to cut off the current by a sudden rise of the resistance at a predetermined temperature or more is integrally molded with the fin 40, a separate for controlling the heat emitted from the heating element 51 No need of temperature sensing circuit.

The rotary electrode 52 connected to the heating element 51 is mounted on the rotary shaft 33 of the motor 30, or mounted on the shaft portion of the fin 40 coupled to the rotary shaft 33 of the motor. The rotating electrode 52 is energized by surface contact with the fixed electrode 53. The fixed electrode 53 is connected to the main power source and accommodated in the housing member 56 having the stepped portion. The receiving member 56 is firmly installed by the fastening member 58 on the support plate 34 provided between the back plate 21 and the back cover 35 of the cooking chamber 20. The rotary electrode 52 is similar to a commutator mounted on a rotating shaft of a conventional motor, and the fixed electrode is similar to a brush in contact with the commutator.

The fin 40 is made of a heat-resistant material capable of withstanding the heat of resistance generated from the heating element 51 or a ceramic-based material similar to the heating element 51. Therefore, the fin 40 and the heating element 51 may be formed integrally after a separate preforming process as a different material, or may be integrally formed at once without a separate preforming process as the same material.

For example, when the fin 40 is a general metal or heat resistant polymer material, and the heat generating element 51 is preformed as a ceramic-based material, the fin 40 is integrally formed with the heat generating element 51 by thermal fusion. Alternatively, after preforming only the fin 40 as a metal or heat resistant polymer material, the heating element 51 of the ceramic material is integrally formed by the PVD technique. Alternatively, the fin 40 and the heat generating element 51 are each formed of the same ceramic-based material and integrally formed by molding (consolidation) by pressurization and heat injection at the same time. In these molding methods, it is preferable that the fin 40 and the heating element 51 are each molded from a similar material with physical properties such as thermal expansion coefficient in order to ensure sufficient life after completion. In addition, the fin 40 and the heat generating element 51 are preferably formed into a shape in which the heat generating element 51 covers the surface of the fin 40 in order to enhance the heat generating effect.

Resistance heat generated from the heating element 51 heats the air around it. Accordingly, the fin 40 forms hot air forcing the convection of the ambient air heated by the resistive heat. The hot air is blown into the interior of the cooking chamber 20 through the vent 22 formed in the rear plate 21 of the cooking chamber 20 by the fan 40 to supply heat energy required for cooking of the cooked product, and then the other cylinder. It is sucked out of the cooking chamber 20 through the base 23. Therefore, hot air is forced convection by the fan 40.

According to the microwave oven for hot air convection in which the heating element is integrally formed in the fin disclosed in the present invention, the frictional resistance by the fin and the heating element is significantly reduced because the heating element and the fin are integrally molded. Therefore, the noise due to the frictional resistance can be significantly reduced, and accordingly, the hot air convection can be smoothed to increase the thermal efficiency and the cooking efficiency.

It is not necessary to secure a separate space for installing the heating element, as a result, a more compact microwave oven for hot air convection can be configured.

The heating element formed integrally with the fin has a temperature control characteristic, and as a result, the cooking temperature of the cooking chamber is maintained almost constant, and thus the cooking efficiency can be further increased.

Claims (5)

In the microwave oven for hot air convection comprising a hot air convection means for forcibly convection the ambient air heated by the heat generated from the heat generating means to the cooking chamber, The hot air convection means has a motor and a fan coupled to the rotating shaft of the motor, The heating means is a microwave oven for hot air convection, characterized in that it comprises a heating element formed integrally with the fin and the current supply means for supplying a current to the heating element. The microwave oven for hot air convection of claim 1, wherein the heating element is formed of a ceramic-based material having PTC thermistor characteristics. The microwave oven for hot air convection according to claim 1, wherein the current supply means includes a rotating electrode connected to the heating element and a fixed electrode in surface contact with the rotating electrode. 4. The microwave oven for hot air convection according to claim 3, wherein the rotary electrode is mounted to the fin. 4. The microwave oven for hot air convection according to claim 3, wherein the rotating electrode is mounted on a rotating shaft of the motor.