JPH01318588A - Motor and cooking appliance provided with motor - Google Patents

Abstract

PURPOSE:To save space and to improve the reliability by constructing a microwave oven having dough making function with a single motor and a single shaft. CONSTITUTION:Rotation of a motor 17 is transmitted through a pulley 12 and a belt 13 to a shaft 18. When a food is subjected to microwave heating, a turntable 4 is fixed to a shaft 18 while when dough is made, a dough making bar 10 is fixed to the shaft 18. Rotation is made through a single motor and a single shaft coupled thereto both when the turntable is used in microwave cooking and when the dough making bar is used in caking dough. By such arrangement, space can be saved, cost can be reduced and the number of parts at the control section can be decreased, resulting in the improvement of reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the control of the rotational speed of an electric motor, and particularly to a motor for driving a turntable included in an oven range with a bread kneading function.

Prior Art The prior art will be explained with reference to FIG. FIG. 11 (at is a structural diagram when food is heated with high frequency. Food 2 placed on plate 1 is high frequency heated by high frequency waves output from magnetron 3. At this time, plate 1 and food 2 is rotated in the heating chamber 5 by the rotation of the turntable 4, so it can be heated evenly.The rotation speed at this time is 5 to 5 rpm.
It becomes.

The turntable 4 is connected to a rotating shaft 7 of a motor 6 located at the bottom of the heating chamber 5, and is configured to follow the rotation of the motor 6. FIG. 11 fbl is a structural diagram when kneading bread. The bread material 9 in the bread case 8 is kneaded using the kneading rod 1o. At this time, the kneading rod 10 is connected to the kneading shaft 11 passing through the hole at the bottom of the heating chamber 5, and the kneading shaft 1
1 is rotated by a pulley 12 and a belt 13 in accordance with the rotation of a motor 14, and rotates a kneading bar 10 in a bread case 8. The rotation speed at this time is about 300 rpm, which is about 60 times faster than the rotation speed of the turntable 4.

Problems to be Solved by the Invention However, the conventional structure has the following problems. First, large holes must be made in the bottom of the heating chamber to allow two shafts to pass through, one shaft 7 to which the turntable 4 is attached, and another kneading shaft 11 to which the kneading bar 10 is attached, to prevent radio wave leakage. A complicated mechanism, such as a choke structure, must be provided at the bottom of the heating chamber for this purpose, and as a result, the overall external shape, especially the height, of the cooking device becomes large, making it unsuitable for the recent demands for space saving. Second, dedicated motors are required for high-frequency heating and bread kneading, which is disadvantageous in terms of space saving and cost benefits. Thirdly, it is necessary to control the two motors individually, so two control circuit systems are required.
The reliability of the system decreases due to the use of a large number of semiconductor components (which increases the complexity), and the cost increases due to the use of two systems of control, making it difficult for users to use cheaper products.

The present invention solves these conventional problems,
The purpose is to provide users with a cheap, space-saving and highly reliable bread kneading function that can be used in the microwave oven.

Means for Solving the Problems In order to achieve the above object, the microwave oven with a bread kneading function of the present invention has a single kneading bar for both when using a turntable for high frequency heating cooking and when using a kneading bar for bread kneading. A motor rotates on one shaft connected to the motor, and when rotating at a low rotation speed, the minimum stable rotation speed of the motor is set.

Function: The microwave oven with bread kneading function of the present invention is configured with one motor and one shaft, which eliminates the need for the conventional complicated choke structure, and saves space considerably, including the ability to eliminate one motor. You can expect.

In addition, the cost is low and the number of parts in the control section can be reduced, so reliability is much higher than in the past.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 2 fal is a cross-sectional structural diagram of the bread kneading microwave oven according to the present invention. The rotation of motor 17 is controlled by pulley 1.
2 and the belt 13 to the shaft 18. When heating foods with high frequency, the turntable 4 shown in Fig. 2 tb) is attached to the shaft 18, and when kneading bread ingredients, the turntable 4 shown in Fig. 2 fcl is attached to the shaft 18.
A kneading rod 10 shown in is attached to a shaft 18.

Further, the food in the heating chamber 5 is high-frequency heated by the magnetron 3 and electrically heated by the upper heater 15 and the lower heater 16. Reference numeral 32 denotes rotation speed detection means for detecting the rotation speed of the motor 17 by a combination of a disc 34 with a slit and a photointerrupter 35.

Figure 3 shows the front operation section of the bread kneading oven according to the present invention.
When the user selects the key 19, sets the bread making ingredients and equipment, and presses the "start" key 21, the bread kneading operation begins. - Blade To perform high-frequency heating, select the "Microwave" key 20, set the heating time with the timer knob 22, place 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 settings of categories and cooking time, or to cancel heating cooking.

FIG. 4 is an electrical circuit diagram of the control section of the bread kneading microwave oven according to the present invention. , during kneading, the microcomputer 26 (hereinafter abbreviated as microcomputer) is connected to output port 03.
, 04 alternately output gate signals synchronized with the 50/60H2 power supply signal to the phase directional thyristors 27 and 28, thereby causing the capacitor motor 17 to repeat forward and reverse rotations. This will be explained using the timing chart in FIG.

The ACioov signal is converted into a DC waveform by the power signal conversion circuit 31 shown in FIG. 4, and read by the 1° port of the microcomputer 26. The microcomputer 26 uses the zero cross timing read from the 10 boat, and uses C3 for forward rotation and C for reverse rotation.
By constantly outputting H output from 4, capacitor motor 1
7 can rotate forward or reverse. At this time, almost 100% power is applied to the capacitor motor 1, so 5
．． When kneading, the capacitor motor 17 is 1800r
Rotates at pm (at 5QHz). Boo 1 no 1 in figure 2
2 ratio, the rotation speed of the shaft 18 is now reduced to 1/6, that is, 3
It becomes 00 rpm. Next, motor control during high-frequency heating will be explained. Since foods and containers containing foods are placed on the turntable 4 in Fig. 2, the
The rotation speed is quite low compared to r pm (5 to 5 r p
It is necessary to rotate the turntable 4 at a speed of about rn). Therefore, by supplying low power electric power to the capacitor motor 17, a speed of 5 to 6 rpm is achieved. 6th
This will be explained using the timing chart shown in the figure. The microcomputer 26 in FIG. 4 converts the ACloov signal into a DC waveform by the power signal conversion circuit 31 and reads it at the 1o port. In order to reduce the power to the capacitor motor 17, it is energized for half a cycle and then energized for a certain period. No (4 half cycles in Figure 6), and repeat this forever. Hereinafter, this will be referred to as pulse removal control. As a result, the power input to the capacitor motor 17 drops to about 20%, but in order to further reduce the power, the timing of outputting the gate signal to the phase 4 directional thyristor 27, that is, the H signal of the 03 output of the microcomputer 26, is determined by the power source. Rather than setting the phase near zero crossing, it is intentionally delayed by several tens of degrees. The conduction angle control (hereinafter referred to as phase control) for the capacitor motor 17 can be set in about nine steps in units of approximately 2σ (FIG. 7).

By combining this phase control and pulse removal control, fine control of the capacitor motor 17 at low power becomes possible. However, since the capacitor motor 17 has a low power input of about 10% of the normal input, there is a lack of torque to begin with, and load (weight of food) fluctuations and AC
The rotation speed of the turntable easily fluctuates due to fluctuations in the 100V voltage, changes in belt tension and temperature, and changes in the position where food is placed (referred to as unbalanced load).

On the other hand, when the capacitor motor 17 is controlled at an extremely low speed of about 5 to 5 rpm by a combination of phase control and pulse removal control as described above, the relationship between the power input to the capacitor motor 17 and the rotation speed is as shown in Fig. 8. The characteristics are shown in a graph.

For example, under condition A, when the AC 100V voltage drops to 85V and the weight of the food, that is, the load, is 500 CI, if you gradually increase the power from O, the turntable rotation speed will once reach 5.
It is stable in the A1 region of approximately rpm, and if the power is increased beyond this, the rotation speed suddenly increases to 60 rpm, which is a rotation speed that cannot be used as a turntable for placing food.

Even when conditions are changed like conditions B and C, 4 to 5 rpm
There is a stable area such as 81 and C1 of change. This shows the same characteristics even when various conditions such as temperature blindness, strength of belt tension, and unbalanced load are changed in addition to fluctuations in AC 100V voltage and load. That is, there is a region where it is stable at 4 to 5 rpm. Therefore, this stable region is called the first stable rotational speed region. This 4 to 6 rpm is the optimum turntable rotation speed during high frequency heating. The rotation speed ratio (pulley ratio) between the turntable and the capacitor motor is 1:6, so when the turntable is 4 to 5 rpm, the capacitor motor is 24 to 36-pm.

Therefore, by combining the disk 34 with slits and the photointerrupter 35 in FIG. 2, the capacitor motor 17
The configuration is such that the motor can be controlled in the above-mentioned first stable rotation speed region by detecting the rotation speed of the motor and optimizing the power input to the motor according to the conditions. In other words, in FIG. 4, by enabling the microcomputer 26 to detect the rotation speed of the capacitor motor 17 using the photo ink club 35, the power can be adjusted according to unbalanced loads during high-frequency heating, voltage/load/temperature fluctuations, and belt tension fluctuations. The capacitor motor 17 can be operated at 4 to 5 rpm, which is the first stable rotational speed range.

On the other hand, in Figure 4, the rotation speed detection input of the capacitor motor 17 that is input to the 11th port of the microcomputer 26 is connected to the shaft of the turntable 4 in Figure 2 when the turntable is to be rotated at 5 to 6 rpm by high-frequency heating. The frequency fluctuates considerably due to looseness in the fitting between the motor 18 and the pulley 12 and the belt 13, and uneven rotation of the capacitor motor 17 itself (caused by trying to rotate it at low speed with low power). . This is shown in FIG. Furthermore, the speed response of the capacitor motor 17 is also poor. That is, after changing the power input to the capacitor motor 17, it takes 1 to 2 seconds for the motor to respond to a constant rotation speed. Furthermore, in FIG. 2, this microwave oven is equipped with a tray 1 placed on a turntable 4, and the shaft 18 is for measuring the food 2 placed on the tray 1. It can move up and down according to the weight of the food 2, and is equipped with a weight sensor 36 at the bottom of the shaft 18 to detect the weight of the food 2.
Therefore, by detecting the weight of the food 2, optimal cooking of the food 2 is realized. In order to reduce errors caused by mechanical catching of the shaft 18 and errors caused by the position of the food 2 when detecting the weight, the turntable 4 is moved to 1 when the user inputs a cooking start command. The weight is detected while rotating for 1/4 period to 1/2 period, and after the weight is detected, heating is started. Therefore, in order to detect the weight and start heating as soon as possible after inputting the start command, it is necessary to quickly start up the rotation of the turntable to a predetermined rotation speed (about 5 to 5 rpm). On the other hand, when attempting to control the rotation speed of the capacitor motor 17 at an extremely low speed, due to the poor response of the capacitor motor 17, the 11 port inputs of the microcomputer 26 shown in FIG. It is also necessary to change the power input setting to the capacitor motor 17 little by little (that is, feedback) to control the change to a predetermined rotation speed.

Therefore, in order to satisfy the above-mentioned contradictory contents, control was performed as shown in FIG. 10. That is, after inputting a start command from the user, power 16, which is a relatively large output, is applied to the capacitor motor for a time t1 (for example, 0.5 seconds) to start the rotation of the capacitor motor.
After that, a rest period (period to stabilize the rotation) is provided at relatively low power 2 for t2 time (for example, 1.5 seconds), and then a relatively short period is provided to quickly start up the rotation of the capacitor motor to the minimum allowable rotation speed. Time t3 (e.g. 0.5
The microcomputer detects the rotation speed of the capacitor motor obtained from the rotation speed detection means every t3 hours, and increases the power setting by several steps every 3 seconds.
When the power is 6 (power 6), the power setting is changed to 1 every time t4 (for example, 2 seconds), which is relatively long compared to t3.
Slowly increase the power in stages, and fix the power setting when the specified number of revolutions reaches 4 to 6 revolutions (Fig. 10+b+
In the graph, power is 10). In other words, in order to detect the weight quickly after starting, the capacitor motor is started to rotate in short time units, and the rotation speed is set to 3r, which is a rotation speed that does not interfere with weight detection and does not cause uneven heating in terms of cooking performance. pm, the power input to the capacitor motor is set for each long time unit. FIG. 10, fat, is a graph showing changes in the rotational speed calculated based on the number of pulses read by the microcomputer at regular intervals. 4 seconds after the start, the rpm exceeded 3 rpm, so from then on, the power was increased by 1 step every 2 seconds.LI9L/
As time goes on, 14 seconds after the start with power 11, the target rotation speed exceeds the equivalent of 6 rpm. Therefore, the load (weight of food, etc.) at this time is fixed at power 10, which is one level lower than power 11, and is controlled in the first stable rotational speed range. The table below shows the pulse extraction ratio and conduction angle settings for each power stage.

A flowchart of these operations (control methods) is shown in FIG. As shown in the figure, at the start of cooking (step 1)
o1), it is determined whether to use high frequency heating, bread kneading, or other cooking such as oven heating, and (step 102.1)
03), for other types of heating, the motor does not rotate (step 104), for bread kneading, the motor is rotated at full power until the end of kneading (steps 105 to 107), and for high frequency heating, the motor is turned on at high power at the beginning. 16 steps
input to the capacitor motor for one hour (step 108,
109), then input low power 2 for t2 time (steps 110 and 111), then t until exceeding 3 rpm.
Increase the power by one step every 3 hours (step 11)
2 to 114), after exceeding 3 rpm, the rotation speed is judged every t4 time (about 2 seconds) and the power is gradually increased by one step until it exceeds 5 rpm (step 1).
15-117). When the speed exceeds 5 rpm, the power is set to lower the power by one level (Step 118), and this is continued until the end of cooking. In other words, set and fix the power so that it is in the first stable rotation speed region of the capacitor motor,
Effects of the Invention of Driving the Turntable at the First Stable Rotation Speed (Step 119) As described above, the high frequency cooking device of the present invention provides the following effects.

(1) Since the configuration is such that one motor and one shaft can handle both bread kneading and turntable rotation, it is complicated to prevent radio wave leakage from the hole through which the shaft passes through the bottom of the heating chamber. This eliminates the need for a choke structure, and together with the ability to reduce the number of motors from two to one, it can be expected to save space considerably.

+21 While satisfying 300 rpm when kneading bread with one motor, the turntable can be rotated from 4 to 400 rpm even during high frequency heating.
It is possible to achieve stable rotation at 5 rpm,
The cost advantage is huge.

(3) Since there is only one motor, only one motor control circuit is required, so fewer parts such as semiconductors are used in the control circuit, which increases the reliability of the control system (reduces failures) and , motor drive can be realized with a low-cost control circuit.

(4) After the start of cooking, the turntable rotates quickly to the predetermined number of revolutions (starts up), so even in a cooker with a built-in weight sensor and a means to detect the weight of food, it is possible to measure the weight quickly after the start of cooking. In addition to saving time, cooking performance can be improved because heating can be controlled according to the weight of the food.

(5) After cooking starts, the rotation of the turntable quickly reaches the specified rotation speed, so when heating a small amount of food, the heating time is short, but high-frequency heating with less uneven heating can be achieved by taking advantage of the advantages of the turntable. .

(6) In a single motor, the rotation speed is stable at an ultra-low speed of about 1/60 of the steady speed, despite fluctuations in AC 100V power supply voltage, temperature fluctuations, load fluctuations, belt tension fluctuations, and unbalanced loads. Now I can control it.

[Brief explanation of the drawing]

FIG. 1 is a control flowchart of an electric motor according to an embodiment of the present invention, FIG. The figure is a front view of the operating unit, Figure 4 is a circuit diagram of the control unit, Figure 5 is a timing chart showing motor control during bread kneading, and Figure 6 is a timing chart showing motor control during high frequency heating. Chart, Figure 7 is an explanatory diagram showing the method of phase control of the motor, Figure 8 is a graph showing the relationship between power input to the motor and rotation speed during ultra-low speed operation,
Fig. 9 is a waveform diagram of the 743711 input (waveform of the feedback output circuit), Fig. 10 ial is a characteristic diagram showing the change in motor rotation speed from the start of high-frequency heating, Fig. 10 [bl is a diagram showing the change in the motor rotation speed from the start] Fig. 11 is an explanatory diagram showing changes in the input power settings of (all BL are cross-sectional views of conventional microwave ovens. 1... Receiver is a plate, 2... Food, 3 ...
...Magnetron, 4...Turntable,
5... Heating chamber, 10... Kneading bar, 17
... Capacitor motor, 18 ... Axis, 2
6...Microcomputer, 31...Power signal conversion circuit, 32...Rotation speed detection means. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure Z--Food 3--Magnetron 4--Turntable 5--Kenji chamber Figure 2 IO-Konesai Figure 3? 4 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Tgin 7&j (b) ↑
T Ginkai (S Kori Suda

Claims (2)

[Claims] (1) A control unit having a single motor, a rotation speed detection means for detecting the rotation speed of the motor, a selection means for selecting a control rotation speed of the motor, and a multi-stage output setting means for the motor. The control rotation speed that can be selected is a steady rotation speed and a rotation speed lower than the steady rotation speed.
An electric motor of a type, and this ultra-low rotational speed is a first stable rotational speed when output is gradually added to the motor from 0. (2) 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 multifunction a control unit capable of setting power in stages, the control unit controls the motor at two speeds, a steady speed and an ultra-low speed, depending on the selected category, and when the ultra-low speed control is performed, the motor is started. When the key is input, the motor starts rotating at a low power input, and while inputting the rotation speed of the motor from the rotation speed detection means at fixed time intervals, the power input is gradually increased, and the power input is gradually increased. When the optimum rotational speed is exceeded, the power input setting to the motor is stopped from increasing, and the power setting is fixed at the previous power setting that exceeds the optimum rotational speed, thereby achieving stable ultra-low speed rotation. Cooker with electric motor to get control.