JPS5835359B2 - microwave oven - Google Patents

Description

Detailed Description of the Invention The present invention provides a microwave oven using a high frequency oscillator and a resistance heating element as heating sources, while suppressing the temperature rise of electrical components such as the high frequency oscillator and structural components such as an outer box, and reducing the temperature of the air inside the heating chamber. The invention is characterized by means for shortening the rise time of.

Conventional microwave ovens generally include a radio wave stirring blade and a resistance heating element in the heating chamber to prevent uneven heating that occurs in the heated object.

Furthermore, high-frequency energy generated from a high-frequency oscillator is supplied into the heating chamber through a metal waveguide having a radio wave emission port in a part of the peripheral wall of the heating chamber.

With this structure, the air temperature in the heating chamber can be set to 250, for example.
When heating the food to a temperature of 0.degree. C. for cooking, the heat in the heating chamber is transmitted through the waveguide and reaches the high-frequency oscillator, and the high-frequency oscillator is likely to be damaged by the heat.

Therefore, when heating with the heat of a resistance heating element, it is necessary to limit the use to heating the object by the radiant heat from the resistance heating element, and to prevent the air temperature in the heating chamber from rising as much as possible. In other words, the air circulation inside and outside the heating chamber was improved to prevent the temperature of the walls of the heating chamber from rising as much as possible, thereby suppressing the conduction of heat to the high frequency oscillator and the like as much as possible.

Furthermore, in the conventional example described above, food scraps and oil vapor scattered from the food being heated adhere to the radio-wave stirring blades provided in the heating chamber, and sometimes they are baked on and difficult to remove, making cleaning difficult.

The present invention operates the blower when the high-frequency oscillator is in operation or when the air temperature in the heating chamber exceeds a set value due to the resistance heating element and the resistance heating element stops operating. The purpose is to suppress the rise in temperature of structural parts such as the outer box of a microwave oven, and to speed up the rise time of the air temperature in the heating chamber to shorten cooking time.

An embodiment of the microwave oven of the present invention will be described with reference to FIGS. 1, 2, and 3.

Fig. 1 is a sectional view of the main parts of the microwave oven of the present invention, Fig. 2 is a top view seen from the direction of arrow AB in Fig. 1, Fig. 3 is the same as Fig. 1,
FIG. 3 is an electrical circuit diagram showing connections of main electrical components corresponding to FIG. 2;

1 and 2, resistance heating elements 2 are provided above and below in a heating chamber 1 surrounded by a metal wall, and a mounting table 4 on which an object to be heated such as food 3 is placed is removably housed. has been done.

A door 1a is provided at the front of the heating chamber 1 to minimize release of thermal energy and high frequency energy within the heating chamber 1 to the outside.

The heating chamber 1 is surrounded by a heat insulating layer 5.

At the center of the upper surface of the heating chamber 1, a radio wave stirring chamber 8 is provided which houses a radio wave stirring blade 7 with a heat shield plate 6 interposed therebetween.

The heat shield plate 6 is made of a dielectric material such as glass ceramic which has low high frequency loss and is heat resistant, and prevents the high temperature air in the heating chamber 1 from flowing into the radio wave stirring chamber 8.

The radio wave stirring blade 7 is connected to a rotating shaft 7a made of a dielectric material with low high frequency loss, and a conductor 7b passing through the radio wave emission port 9 is attached to the rotating shaft 7a.

The rotating shaft 7a is fixed to the waveguide 11 by a nut 7c,
A rotatable radio wave stirring blade 7 is attached between a washer 7a made of a dielectric material with little high frequency loss and a separator plate 7e.

Although the separator plate 7e is rotatable, its position in the vertical direction is fixed to prevent the conductor 7b and the radio wave stirring blade 7 from coming close to each other and causing sparks.

The radio wave emission port 9 is an opening of a waveguide 11 that transmits high frequency energy (radio waves) generated from a high frequency oscillator 10, and is located at the center of the upper surface of the radio wave stirring chamber.

A blower 12 is provided that cools the high frequency oscillator 10 and sends air that drives the radio wave stirring blades 7.

The air coming out of the blower 12 is transferred to the air guide pipe 13, the high frequency oscillator 10, the air guide pipe 14, the ventilation holes 8a and 8b provided on the side wall of the radio wave stirring chamber 8, the air guide pipe 15, and the exhaust hole provided in the outer box 16. 16b and is discharged to the outside.

Fresh air is sucked into the blower from the outside through an intake hole 16a provided at the bottom of the outer box 16.

Legs 17 are attached to the lower part of the outer box 16.

In FIG. 3, 17a and 17b are input terminals for applying a power supply voltage, and 18 is a changeover switch for selecting heating means for either the resistance heating element 2 or the high-frequency oscillator 10.

In FIG. 3, the changeover switch 18 is connected to the resistance heating element 2 side.

Reference numeral 19 denotes a temperature-sensitive switch for arbitrarily setting the air temperature in the heating chamber 1. The changeover switch 18 selects the resistance heating element 2, and when the air temperature in the heating chamber 1 exceeds the set value, the resistance heating element 2 is switched on. The blower 12 is turned on at the same time as it is turned off.

The temperature sensing switch 19 is formed from a temperature sensing element 19a and a switch 19b, like a liquid expansion type thermostat, for example.

Reference numeral 20 denotes an electromagnetic switch, which is connected to the input side of the drive circuit 21 of the high frequency oscillator 10, which is connected to the high ball transformer 21a, the high mocapacitor 21b and the rectifier 21c.

When the high-frequency oscillator 10 side is selected by the selector switch 18, the electromagnetic coil 21a of the electromagnetic switch 20 is energized to close the contact 21b.

21c is connected so that the high frequency oscillator 10 oscillates and the blower 12 is turned on.

That is, one end of the blower 12 is electrically connected to the input terminal 17b to which the power supply voltage is applied, and the other end is divided into three parts, one of which is connected to the contact of the temperature-sensitive switch 19 to heat the heating chamber by the resistance heating element 2. When the air temperature inside 1 exceeds the set value, the input terminal 17a becomes electrically conductive, and the other terminal is connected between the electromagnetic switch 20 and the drive circuit 21, and when the contact 21b of the electromagnetic switch 20 becomes electrically conductive, the input terminal 17a becomes electrically conductive. It becomes electrically conductive with the terminal 17a.

In addition, in FIG. 3, when the door 1a is opened while the high-frequency oscillator 10 is oscillating, there is a timer that sets the energization time of the resistance heating element 2 or the high-frequency oscillator 10.
Switches to stop the oscillation are omitted.

Next, the operation of the microwave oven of the present invention will be explained.

When the high-frequency oscillator 10 is energized, the high-frequency energy is transmitted through the waveguide 11, enters the radio wave stirring chamber 8 through the radio wave emission port 9, is stirred by the radio wave stirring blade 7, and then passes through the heat shield plate 6 and is heated. The interior of the chamber 1 is irradiated, and the object to be heated 3 is dielectrically heated.

Dielectric heating can heat the inside and outside of the object at the same time, but the surface of the object cools due to heat dissipation, making it difficult to brown the object.

Therefore, if the resistance heating element 2 is energized to raise the air temperature in the heating chamber 1 to a high temperature of, for example, 250° C., it becomes easy to brown the entire surface of the object to be heated.

That is, the entire surface of the food is browned by the thermal energy generated by the resistance heating element 2, and the interior thereof is heated by the high frequency energy generated by the high frequency oscillator 10.

Also, only the upper part of the resistance heating element 2 is energized to make it red hot,
By emitting a large amount of infrared rays, it is possible to brown only the top surface of the object to be heated.

Even if the temperature inside the heating chamber 1 is high, the heating chamber 1 and the waveguide 11 are separated by the heat shield plate 6 and the radio wave stirring chamber 8.
The temperature of the waveguide 11 can be kept considerably lower than the temperature of the air inside the heating chamber 1.

Since the air that drives the radio wave stirring blades 7 is passed through the radio wave stirring chamber 8, the heat in the heating chamber 1 is transferred to the heat shield plate 6.
Even if the heat is conducted into the radio wave stirring chamber 8, most of the heat is released to the outside by the wind.

Furthermore, since a considerable amount of heat is dissipated in the waveguide 11 on the way from the radio wave emission port 9 to the high-frequency oscillator 10, it is necessary to protect the high-frequency oscillator 10 connected to the end of the waveguide 11 from damage due to heat. Can be done.

Moreover, since the heat shield plate 6 itself is also cooled by the wind,
It can prevent damage caused by heat.

When the air temperature in the heating chamber 1 exceeds the set value during heating by the high frequency oscillator 10 or heating by the resistance heating element 2, the blower 12 is turned on and the air is sucked in from the air intake hole 16a provided in the outer box 16. The fresh air is blown into the space between the outer wall of the heating chamber 1 and the outer box 16 and into the high-frequency oscillator 10 for forced air cooling, thereby preventing damage to electrical parts such as the high-frequency oscillator 10 and structural parts such as the outer box 16 due to heat. suppress the temperature rise.

Since the blower 12 is turned off until the air temperature in the heating chamber 1 reaches the set value during heating by the resistance heating element 2, the rise time of the air temperature in the heating chamber 1 is accelerated and the cooking time is shortened. can do.

In addition, a radio wave stirring chamber 8 is provided in the center of the upper surface of the heating chamber 1,
Furthermore, since there is a radio wave emission port 9 at the center of the top surface of the radio wave stirring chamber, the radio wave emission port 9 is made circular and the center 1ζ conductor 7b
By making it penetrate through the wire, it is possible to radiate radio waves symmetrically from side to side and front to back, and it is also easy to reduce uneven heating.

Furthermore, since the heat shield plate 6 prevents the high-temperature air in the heating chamber 1 from flowing into the radio-wave stirring chamber, it is possible to prevent the radio-wave stirring blades from becoming contaminated by food scraps, oil vapor, etc. that fly away during heating. The interior of the heating chamber 1 can be cleaned easily.

As described above, according to the present invention, the high frequency oscillator 10
and a resistance heating element 2 as heat sources, the temperature inside the heating chamber 1 can be set to an arbitrary temperature, and when the air temperature in the heating chamber 1 exceeds the set value during heating by the high frequency oscillator 10 or due to the resistance heating element 2, The blower 12 is turned on and fresh air from the outside is sucked in through the intake hole 16a provided in the outer box 16 and is drawn into the space between the outer wall of the heating chamber 1 and the outer box 16 and into the high-frequency oscillator 10 for forced air cooling. Therefore, damage to electrical components such as the high frequency oscillator 10 due to heat and rise in temperature of structural components such as the outer box 16 can be suppressed.

In addition, since the blower 12 is turned off when the temperature in the heating chamber 1 is being raised by the resistance heating element 2, the temperature rise in the heating chamber 1 by the resistance heating element 2 is accelerated, and the cooking time is increased. To provide a microwave oven that can shorten the time.

Furthermore, by completely covering the periphery of the heating chamber with the heat insulating layer 5 and the heat shield plate 6 as in the embodiment of the present invention, or by covering it appropriately as necessary, the inside of the heating chamber 1 can be heated to a high temperature of 250°C. Since the structure allows the food to be heated with high-frequency energy, the entire surface of the food can be browned using high-temperature air, or only the top surface of the food can be browned using infrared rays. To provide an easy-to-use microwave oven.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of the microwave oven of the present invention, and FIG. 2 is a top view seen from the AB force direction in FIG. 1. FIG. 3 is an electrical circuit diagram showing connections of main electrical components corresponding to FIGS. 1 and 2. FIG. 1... Heating chamber, 2... Resistance heating element, 5
...Heat insulation layer, 6...Heat shield plate, 7...
...Radio wave stirring blade, 8...Radio wave stirring chamber, 10...High frequency oscillator, 11...
Waveguide, 12...Blower, 16...Outer box, 17a, 17b...Input terminal, 18...
...Selector switch, 19...Temperature-sensitive switch,
20... Electromagnetic switch, 21... Drive circuit of the high frequency oscillator 10.

Claims (1)

[Claims] 1 A high frequency oscillator 10 and a resistance heating element 2 are used as heating sources,
In a microwave oven in which the heating chamber 1 is surrounded by a heat insulating layer 5 and a heat shield plate 6, the blower 12 is turned on during heating by the high frequency oscillator 10, and fresh air from the outside is sucked in from the air intake port 16a provided in the outer box 16. The high frequency oscillator 10 is blown into the heating chamber 1 for forced cooling.
The resistance heating element 2 is controlled on and off by a temperature-sensitive switch 19 that arbitrarily sets the internal air temperature, and when the resistance heating element 2 is off, the blower 12 is turned on to heat the fresh air drawn from the outside through the intake hole 16a. The high frequency oscillator 1 is blown into the space between the outer wall of the chamber 1 and the outer box and the high frequency oscillator 10.
0 etc. and structural parts such as the outer box 16 are forcibly cooled, and when the resistance heating element 2 is on, the blower 12 is turned off to speed up the rise time of the air temperature in the heating chamber 1. range.