JPH0833208B2 - Cooking device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a microwave oven with a kneading function.

Conventional Technology Conventional technology will be described with reference to FIG. FIG. 10 (a) is a structural diagram when the food is heated by high frequency. The food 2 placed on the plate 1 is heated at high frequency by the high frequency output from the magnetron 3. At this time, the plate 1 and the food 2 are rotated in the heating chamber 5 by the rotation of the turntable 4, so that they can be heated uniformly. The rotation speed at this time is 5 to 6 rpm. The turntable 4 is connected to a rotating shaft 7 of a motor 6 at the bottom of the heating chamber 5, and is configured to follow the rotation of the motor 6. FIG. 10 (b) is a structural diagram when kneading bread. Kneading the bread ingredients 9 in the bread case 8
Knead with the kneading rod 10, and at this time, the kneading rod 11 is connected to the kneading shaft 11 that penetrates the hole at the bottom of the heating chamber 5 and the kneading rod 11
Is rotated according to the rotation of the motor 14 by the pulley 12 and the belt 13, and the kneading rod 10 in the pan case 8 is rotated. The rotation speed at this time is about 300 rpm, and the turntable 4
Compared to the rotation speed of, it is about 60 times faster.

Problems to be Solved by the Invention However, the conventional structure has the following problems. First, there must be a large hole for penetrating the bottom of the heating chamber into two shafts, the shaft 7 to which the turntable 4 is attached and the kneading rod 11 to which the kneading rod 10 is attached. Therefore, a complicated mechanism such as a choke structure must be provided in the bottom of the heating chamber, and as a result, the outer shape of the entire cooking device, in particular, the height of the cooking device becomes large, which does not meet the recent demand for space saving. Secondly, a dedicated motor is required for each of high-frequency heating and bread kneading, which is disadvantageous in terms of space saving and cost merit. Thirdly, since it is necessary to control two motors individually, two systems of control circuits are required, and as the number of semiconductor components is increased due to complexity, system reliability is reduced and control of two systems is required. The cost was so high that users could not use cheap products.

The present invention solves such a conventional problem, and an object of the present invention is to provide a user with a cheap, space-saving and highly reliable microwave oven with a bread kneading function.

Means for Solving the Problems In order to achieve the above object, the microwave oven with a bread kneading function of the present invention uses a single motor when using a turntable in high frequency cooking and when using a kneading rod during bread kneading. Moreover, it rotates on one shaft connected to the motor, and when it rotates at a low rotation speed, it is the minimum stable rotation speed of the motor.

Action By constructing the microwave oven with a bread kneading function of the present invention with one motor and one shaft, it becomes unnecessary to use the conventional complicated chute structure, and it is possible to expect a considerable space saving, including the fact that one motor can be eliminated from the beginning. it can.
In addition, the cost is low and the number of parts of the control unit can be reduced, so that the reliability is much higher than the conventional one.

Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 (a) is a cross-sectional structural diagram of a microwave oven with a bread dough. The rotation of the motor 17 is transmitted to the shaft 18 by the pulley 12 and the belt 13. When heating food at high frequency, the turntable 4 shown in FIG. 2 (b) is attached to the shaft 18, and when kneading bread ingredients, the kneading rod 10 shown in FIG. 2 (c) is used.
Attach to. The food in the heating chamber 5 is heated by the magnetron 3 at high frequency, and is electrically heated by the upper heater 15 and the lower heater 16. 32 is a disk with slits
Motor 17 by combining 34 and photo interrupter 35
It is a rotation speed detecting means for detecting the rotation speed of.

FIG. 3 is a front operation part of the oven for baking bread according to the present invention. The user selects the "bread" key 19 when making bread, sets the ingredients and equipment for making bread, and presses the "start" key 21 to start the kneading operation. On the other hand, when performing high frequency heating, the "range" key 20
Select, select the heating time with the timer knob 22, put the food in the heating chamber, and press the "Start" key 21 to start high frequency heating. Further, by using the "cancel" key 23, it is possible to instruct to cancel the setting of the category or the cooking time or stop the cooking.

FIG. 4 is an electric circuit diagram of a control unit of the oven for baking bread according to the present invention. Capacitor motor 17 by the pan connector when the microcomputer 26 (hereinafter referred to as microcomputer) is for outputting a gate signal synchronized with the alternately 50 / 60Hz power signal from the output port O _3, O ₄ in the phase directional thyristor 27, 28 Repeat forward and reverse. This will be described with reference to the timing chart of FIG.

AC100V signal by the power supply signal conversion circuit 31 of FIG.
Converts to a DC waveform and reads it at the I ₀ port of the microcomputer 26. At the zero-cross timing read from the I ₀ port of the microcomputer 26, it always outputs H output from 0 ₃ during forward rotation and 0 ₄ during inversion. 17 can be forward / reverse. At this time, almost 100% of the electric power is applied to the capacitor motor 17, so when kneading the capacitor motor
The 17 rotates at 1800 rpm (at 60 Hz). Pulley 1 in Figure 2
Due to the 2 ratio, the number of rotations of the shaft 18 is then 1/6, ie, 300 rpm. Next, motor control during high frequency heating will be described. As shown in FIG. 2, food or a container containing food is placed on the turntable 4, so it is necessary to rotate the turntable 4 at a considerably lower rotation speed (about 5 to 6 rpm) than 300 rpm at the time of kneading bread. Therefore, 5 to 6 rpm is realized by supplying low power to the condenser motor 17. This will be described with reference to the timing chart of FIG. Fourth
The microcomputer 26 in the figure converts a signal of AC100V into a DC waveform by the power supply signal conversion circuit 31 and reads it at the I ₀ port, but does not energize for a certain period after energizing for a half period to make the power supply to the capacitor motor 17 low power. (4 half cycles in Fig. 6), this is repeated all the time. Hereinafter, this is referred to as pulse extraction control. As a result, the power input to the condenser motor 17 drops to about 20%, but to make it even lower,
FIG. 4 The gate signal to the phase directional thyristor 27, that is, the timing of outputting the H signal of the O ₃ output of the microcomputer 26 is intentionally delayed by several tens of degrees instead of near the zero cross of the power supply phase.
The conduction angle control to the condenser motor 17 (hereinafter referred to as phase control) can be set in about 20 steps in 9 steps (7th step).
Figure). By combining this phase control and pulse extraction control, fine control with low power with the capacitor motor 17 is possible. However, for the condenser motor 17, since the low power input is about 10% of the normal input, there is originally insufficient torque, and load (food weight) fluctuations and AC100V
The rotation speed of the turntable easily fluctuates due to fluctuations in voltage, fluctuations in belt tension and temperature, fluctuations in the position on which food is placed (referred to as unbalanced load).

Therefore, the configuration is such that the rotation speed of the condenser motor 17 can be detected by the combination of the disk 34 with slits and the photo interrupter 35 shown in FIG. That is, in FIG. 4, the microcomputer 26 enables the photo interrupter 35 to detect the number of revolutions of the condenser motor 17,
During high-frequency heating, the condenser motor 17 can be operated with power according to uneven load, voltage / load / temperature fluctuations, and belt tension fluctuations, and the turntable can be rotationally controlled at 5 to 6 rpm.

On the other hand, in FIG. 4, when the rotation speed detection input of the condenser motor 17 input to the I ₁ port of the microcomputer 26 is about to rotate the turntable at 5 to 6 rpm by high frequency heating, the turntable 4 and the shaft of FIG. The frequency fluctuates considerably due to the looseness of fitting with 18, the looseness of fitting with the pulley 12 and the belt 13, and the uneven rotation of the condenser motor 17 itself (which occurs when trying to rotate at low speed with low power). . This is shown in FIG. Moreover, the speed response of the capacitor motor 17 is also poor. That is, it takes 1 to 2 seconds to change the power input to the capacitor 17 and to respond to near the constant rotation speed. Therefore, even if the power input to the condenser motor 17 is changed finely, for example, for about 0.1 seconds, it only causes uneven rotation, and the microcomputer is used at coarse time intervals.
It is best to count 26 I ₁ inputs and vary the power input to the capacitor motor 17 based on this count (ie feedback).

That is, the control method will be described with reference to FIG. Simultaneously with the start in FIG. 9 (b), the low-power power 1 energizes the capacitor motor for 2 seconds. At the same time, the condenser motor begins to rotate, and the microcomputer detects the number of rotations in the system described above. In Fig. 9 (a), the microcomputer is 2
It is a graph showing the change in the rotation speed converted based on the number of pulses read every second. 1 power every 2 seconds
When it is increased step by step, it will exceed the target rotation speed of 6 rpm at 14 seconds after the start when it becomes Power 7. Therefore, with the power 6 that is one step lower than the power 7, the load (weight of food, etc.) at this time is fixed and controlled thereafter. The table below shows the pulse extraction ratio and conduction angle settings for each power stage.

A flow chart of these operations (control method) is shown in FIG. As shown in the figure, start cooking (step
101) determines whether it is high frequency heating, bread kneading, or other cooking such as oven heating (steps 102, 103),
For other heating, the motor does not rotate (step 104),
For bread kneading, rotate the motor at full power until the end of kneading (steps 105 to 107). For high frequency heating, start from the low power 1 stage (step 10).
8) The rotation speed is judged every 2 seconds, and the power is gradually increased step by step until it exceeds 6 rpm (steps 109 to 11).
2).

When the speed exceeds 6 rpm, the power is set to one level lower (step 113), and the cooking is continued thereafter (steps 114 and 115).

EFFECTS OF THE INVENTION As described above, according to the high frequency heating cooker of the present invention, the following effects can be obtained.

(1) With one motor and one shaft, it is possible to satisfy both the rotation at the time of pan kneading and the rotation of the turntable. Therefore, the electric wave from the hole through the shaft penetrating the bottom of the heating chamber is also prevented, which is complicated. The need for a choke structure is no longer necessary, and it is possible to expect considerable space savings in addition to being able to originally use two motors.

(2) It is possible to achieve stable rotation of the turntable at 5 to 6 rpm even with high frequency heating while satisfying 300 rpm for kneading the bread with one motor, which is very cost effective.

(3) Since there is only one motor, only one control circuit is required for the motor, so the number of parts such as semiconductors used in the control circuit can be reduced, which increases the reliability of the control system (the failure rate is low. In addition, the motor drive can be realized with a low-cost control circuit.

[Brief description of drawings]

FIG. 1 is a control flowchart of an electric motor according to an embodiment of the present invention, and FIGS. 2A to 2C are cross-sectional views of a microwave oven provided with the electric motor according to an embodiment of the present invention and perspective views of parts. 3, FIG. 3 is a front view of the operation unit, FIG. 4 is a circuit diagram of the control unit, FIG. 5 is a timing chart showing motor control at the time of bread kneading, and FIG. 6 is motor control at the time of high frequency heating. 7 is an explanatory diagram showing the method of controlling the phase of the motor, FIG. 8 is a waveform of the microcomputer I ₁ input (waveform of the feedback output circuit), and FIG. 9 (a) is high-frequency heating. Fig. 9 (b) is a characteristic diagram showing a change in the number of revolutions of the motor from the start, Fig. 9 (b) is an explanatory diagram showing a change in the input power setting to the motor from the start, and Figs. 10 (a) and (b) are It is sectional drawing of the conventional microwave oven, respectively. 1 ... saucer, 2 ... food, 3 ... magnetron, 4 ...
… Turntable, 5… Heating room, 10… Kneading rod, 17…
… Capacitor motor, 18… Axis, 26… Microcomputer, 31…
… Power supply signal conversion circuit, 32… Rotation speed detection.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuaki Soi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Katsunori Harima, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Akihisa Takano 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshio Mimoto, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References Kaihei 1-196421 (JP, A)

Claims (1)

[Claims] 1. A single motor, a rotation speed detection means for detecting the rotation speed of the motor, a category selection means for selecting a cooking category, a start key for inputting a cooking start command, and a motor for the motor. And a control unit having multi-stage power setting means, wherein the control unit controls the motor to operate at a constant speed or an ultra-low speed according to the selected category.
At a very low speed control, the motor is operated at a relatively high power for a certain time t1 and then at a relatively low power for a certain time t2 at the time of the ultra-low speed control, and then at a constant power. The power setting is increased by several steps every time t3, and when the rotation speed obtained by the rotation speed detecting means reaches the minimum allowable rotation speed, finally the fixed time is reached.
Cooker that switches to rotation speed control at every t4 for a fixed time longer than t3.