JPS58314B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency heating device having a defrosting and heating function.

Conventionally, in this type of high-frequency heating device, such as a microwave oven, when thawing an object to be heated, that is, a food to be cooked, the high-frequency generator is operated intermittently.

However, heating by high frequency is dielectric heating (internal heating), and therefore, if the dielectric constant ε and dielectric constant tan δ of the food to be cooked are partially different, a local temperature difference will occur in the food to be cooked. , there will be parts that dissolve and parts that do not.

That is, it is extremely difficult to perform good defrosting.

Moreover, there is an extremely large difference in dielectric constant ε and dielectric power factor tan δ between the dissolved water and the water part of the food to be cooked, and the high frequencies of the water concentrate, making it increasingly difficult to thaw the food properly. It becomes.

Here, the table below shows an example of the partial dielectric properties of the food to be cooked, as well as the dielectric properties of water and ice.

Further, when the food to be cooked has corners or protrusions, there is a problem that only those parts are heated first and melt quickly, while other parts are not easily dissolved.

This invention was made in view of the above circumstances,
The purpose of this is to be able to thaw the object to be heated evenly and satisfactorily regardless of the non-uniform composition or shape of the object to be heated, and also to significantly shorten the thawing time. This provides an excellent high-frequency heating device.

An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes the main body of a high-frequency heating device, such as a microwave oven, on the front of which a door 2 is pivotally supported so as to be freely openable and closable, and an operation panel 3 is provided.

A heating chamber, that is, a cooking chamber 4 is provided in the main body 1 corresponding to the door 2.

A shelf board 5 for placing objects to be heated, that is, food to be cooked, is rotatably provided on the bottom surface of the cooking chamber 4. It is connected to the rotating shaft of 6.

Further, one end of a waveguide 7 is communicated with the ceiling surface of the cooking chamber 4, and a high frequency generator such as a magnetron 8 is provided on the outer periphery of the other end of the waveguide 7.

In this case, the antenna 81 of the magnetron 8 is introduced into the waveguide 7, and the high frequency waves emitted from the magnetron 8 are supplied into the cooking chamber 4 via the waveguide 7.

In addition, in the cooking chamber 4, an upper heater (output 800w) 10 and an upper heater (output 40w) are installed near the ceiling surface in the upper part.
0W) 11 is disposed, and a lower heater (400W) 12 is disposed between the lower shelf board 5 and the bottom surface.

FIG. 3 shows the control circuit.

The AC power supply 20 includes a power switch 21 and a relay 5 to be described later.
2 normally open contacts 52a1, 52a2. The primary winding 241 of the transformer 24 is connected through a changeover switch 22 for switching between microwave cooking using high frequency and oven cooking using heat generated by the heater, and a switch 23 that is opened when thawing cooking is set.
is connected.

A secondary winding 242 of this transformer 24 is connected between the anode and cathode of the magnetron 8 via a rectifier circuit consisting of a capacitor C and a diode D, and a secondary winding 243 is connected to the heater of the magnetron 8. It is connected.

Note that the anode of the magnetron 8 is grounded.

Here, when microwave cooking and defrosting cooking are set, the changeover switch 22 has a movable contact 22c and a fixed contact 221.
When the oven cooking is set, the movable contact 22c and the fixed contact 222 are closed.

One end of the upper heater 10 is connected to the fixed contact 222 of the changeover switch 22 via the upper heater turn-on switch 30, and the other end of the upper heater 10 is connected to the primary winding 241.
and the contact point 52a2.

Further, one end of each of the upper heater 11 and the lower heater 12 is connected to the fixed contact 222 via the upper/lower heater changeover switch 31, and the other ends of the heaters 11 and 12 are both connected to the primary winding 241. It is connected to the connection point with 52a2.

Furthermore, the movable contact 40c of the changeover switch 40 is connected to the fixed contact 221 of the changeover switch 22.

This changeover switch 40 is operated in accordance with the rotation of the motor 6, and has a movable contact 40c and a fixed contact 401.
The contact between the movable contact 40c and the fixed contact 402 is closed for, for example, 5 seconds, and the contact between the movable contact 40c and the fixed contact 402 is closed for, for example, 10 seconds.

A fixed contact 401 is connected to a connection point between the switch 23 and the primary winding 241, and a fixed contact 402 is connected to one end of the lower heater 12.

Furthermore, a door switch 50 and a timer switch 511 are connected to the connection point between the power switch 21 and the contact 52a1.
One end of a relay 52 is connected through the cooking switch 53 in series, and the other end of the relay 52 is connected to the other end of the power source 20 through a cooking switch 53.

The motor 6 is connected to the relay 52 in parallel.

Further, one end of a timer motor 51 is connected to the connection point between the timer switch 511 and the relay 52, and the other end of the timer motor 51 is connected to the connection point between the relay 52 and the cooking switch 53.

Note that the cooking switch 53 has a normally open contact 5 of the relay 52.
2a3 are connected in parallel.

Next, the operation in the above configuration will be explained.

First, food to be cooked, such as frozen food, is placed on the shelf board 5 in the cooking chamber 4, and the door 2 is closed.

Furthermore, while setting thawing cooking on the operation panel 3,
Set the time required for defrosting and cooking.

In this way, when the cooking switch 53 is turned on when the preparation for thawing cooking is completed, the relay 52 is activated and the contact 52 is turned on.
a1, 52a2, 52a3 are closed, and among them, contact 52
Closing a3 forms a self-holding circuit for relay 52.

In addition, the motor 6 operates and the shelf board 5 rotates,
The changeover switch 40 is operated.

Then, the magnetron 8 and the lower heater 12 each operate alternately for a certain period of time.

In other words, as shown in FIG. 4, every time the magnetron 8 operates for 5 seconds (shaded area in the figure), the lower heater 12 operates for 10 seconds (black dotted area in the figure), and if the operation period is T, then the magnetron 8 operates. The time is 1/3T, and the operating time of the lower heater 12 is 2/3T.

In this way, the frozen food in the cooking chamber 4 is heated alternately from inside and outside by the high frequency waves emitted from the magnetron 8 and the heat transmitted from the lower heater 12 via the shelf board 5.

Thereafter, when a preset time has elapsed, the timer switch 511 is turned off, the operation of the relay 52 is stopped, and the thawing cooking ends.

Therefore, not only is the frozen food intermittently heated from the inside by high frequency, but also the frozen food is heated from the outside by the heat generated by the lower heater 12 when the high frequency is interrupted, thereby thawing the frozen food evenly and well. can be done.

Furthermore, in this case, the heating by the lower heater 12 evaporates the water dissolved from the frozen food by high frequency heating, thereby preventing the inconvenience of high frequency waves concentrating on the water.

In addition, when performing such alternate heating, the thawing time is reduced by 1/2 compared to the case of only intermittent heating using conventional high frequency waves.
It has the advantage of being able to shorten the time to 3, making it ideal for business use where decompression is performed multiple times.

Next, FIGS. 5 and 6 show other embodiments of the present invention.
This will be explained with reference to the figures.

In this case, the same parts as in FIGS. 2 and 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

First, in FIG. 5, a stirrer fan 15 for stirring high-frequency waves is provided on the ceiling surface of the cooking chamber 4.

Further, a heater chamber 16 is formed on the right side wall of the cooking chamber 4 in the drawing, and a coil-shaped heater (output 3
00W) 17 and a propeller fan 18 for circulating air in the cooking chamber 4 through the heater 17.

The propeller fan 18 is connected to a rotating shaft of a motor 19 provided outside the heater chamber 16.

On the other hand, in FIG. 6, one end of the defrosting timer motor 60 is connected to the connection point between the contact 52a1 and the switch 23,
The other end of this defrosting timer motor 60 is connected to 1 of the transformer 24.
It is connected to the connection point between the other end of the next winding 241 and the contact 52a2.

Furthermore, the movable contact 61c of the changeover switch 61 is connected to the connection point between the contact 52a1 and the switch 23.

This changeover switch 61 is connected to the defrosting timer motor 60.
The switching operation is performed according to the operation of the movable contact 61c and the fixed contact 611, for example, 7 seconds, and the movable contact 61c and the fixed contact 612 are closed for 7 seconds, for example. There is.

, and the fixed contact 61 connects the switch 23 and the primary winding 2.
It is connected to the connection point with 41.

Further, one end of the motor 19 is connected to the fixed contact 61□, and the other end of the motor 19 is connected to the primary winding 241 and the contact 5.
It is connected to the connection point with 2a2.

Furthermore, the heater 17 is connected in parallel to the motor 19 via a motor turn-on switch 62 .

Note that a motor 151 for driving the starvation fan 15 is connected in parallel to the relay 52.

Therefore, food to be cooked, such as frozen food, is placed on the shelf board 5 in the cooking chamber 4, and the door is closed.

Further, thawing cooking is set and the time required for the thawing cooking is set using a timer.

In this way, when the cooking switch 53 is turned on when the preparation for thawing cooking is completed, the relay 52 is activated and the contact 52 is turned on.
a1, 52a2, 52a3 are closed, and among them, contact 52
Closing a3 forms a self-holding circuit for relay 52.

Further, the motor 151 operates to rotate the stirrer fan 15, and the defrosting timer motor 60 operates to switch the changeover switch 61.

At this time, if the heater turn-on switch 62 is turned on, the magnetron 8, heater 17, and motor 19 each operate alternately for a certain period of time.

That is, as shown in FIG. 7, every time the magnetron 8 operates for 7 seconds (hatched area in the figure), the heater 17 and motor 19 operate for 7 seconds (black dotted area in the figure), and if the operation period is T, then the magnetron 8 The operating time is 1/2T, and the operating time of the heater 17 and motor 19 is also 1/2T.

In this way, the frozen food in the cooking chamber 4 is heated alternately from inside and outside by the high frequency waves emitted from the magnetron 8 and the hot air blown from the heater chamber 16.

In other words, the frozen food can be thawed evenly and satisfactorily.

Thereafter, when a preset time has elapsed, the timer switch 511 is turned off, the operation of the relay 52 is stopped, and the thawing cooking ends.

By the way, during such thawing cooking, if the heater input switch 62 is turned off, the heater 17 will not operate and the cooking chamber 4 will not operate.
Cold air is blown out from inside, and by operating the heater switch 62 to appropriately select between hot air and cold air, optimal thawing can be achieved depending on the type and shape of the food to be cooked. .

That is, thawing cooking using high frequency waves and hot air is suitable for oven-cooked frozen foods such as gratin, pizza pie, and croquettes.

In addition, thawing cooking using high frequency waves and cold air is suitable for frozen foods that have corners or protrusions on the surface. It has the feature of being able to thaw the entire frozen food evenly.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without changing the gist.

As described above, according to the present invention, with the above-described configuration, high frequency waves and heat or wind are alternately supplied into the heating chamber, thereby preventing uneven composition or shape of the object to be heated. However, it is possible to provide an excellent high-frequency heating device that can uniformly and satisfactorily defrost the object to be heated, and can also significantly shorten the defrosting time.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of this invention.
Fig. 1 is an overall configuration diagram, Fig. 2 is a diagram schematically showing the internal mechanism, Fig. 3 is a configuration diagram of the control circuit, Fig. 4 is a diagram for explaining the operation, and Figs. 7 shows another embodiment of the present invention, FIG. 5 is a diagram schematically showing the internal mechanism, FIG. 6 is a configuration diagram of the control circuit, and FIG. 7 is a diagram for explaining the operation. be.・ 4... Heating chamber (cooking room), 8...
High frequency generator (magnetron), 12...Lower heater, 17...Heater, 18...Propeller fan. (5) (6)

Claims (1)

[Claims] 1. A heating chamber, a rotary shelf that is rotatably provided at a predetermined position in the heating chamber and on which an object to be heated is placed, a high frequency generator that supplies high frequency waves into the heating chamber, and a heater provided in the heating chamber. In the high-frequency heating device, the high-frequency heating device has a microwave heating function using high-frequency waves emitted from the high-frequency generator and an oven heating function using heat generated by the heater, in which a current-carrying path for the high-frequency generator and a current-carrying path for the heater are constant. A high-frequency heating device, characterized in that it is provided with a switch that generates signals alternately at intervals of time, and has an added defrosting and heating function based on the alternate operation of a high-frequency generator and a heater.