JPH04322696A - Washing machine - Google Patents

Abstract

PURPOSE:To meet revolution ranging from low speed to high speed without using a speed-changing means, by a method wherein the duty of line voltage applied to stator windings for a d.c. brushless motor is controlled and the revolution of the motor is controlled corresponding to the state of washing. CONSTITUTION:For a d.c. brushless motor 11, the distribution of d.c. voltage made from a commercial electric source 25 through a d.c. electric source 30 for the motor is controlled by a transistor module 31, and the d.c. brushless motor 11 is three-phase driven. By internal operation processing in a microcomputer 24, each base control signal for the three-phase transistor module 31 is outputted, and pulse-duration modulation is done in a PWM circuit 35 for controlling the number of revolution, following which the amplification thereof is done in a base drive circuit 36 and the transistor module 31 is operated. At this point, the value of an on-off duty ratio of line voltage patterns applied to motor-stator windings is, for example, made 1/3 in a low speed and 1/2 in a high speed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to washing in a washing machine.
This invention relates to a washing machine that allows a single motor to handle rotations from low to high speeds by controlling the rotation of the main motor that performs dehydration, etc.

0002

[Prior Art] Conventional fully automatic washing machines use a single-phase induction motor, speed change means using gears, etc., and deceleration means consisting of pulleys and belts, and during low-speed operations such as washing or rinsing, the motor The rotational speed is reduced in two steps to rotate the stirring blades at low speed, and during high-speed operations such as dehydration, only the speed reduction means is used to rotate the rotating tank at high speed. In addition, a drum-type washing machine uses two single-phase induction motors, each of which is used for low speed and high speed. Also, unlike the two examples above, there is also a configuration that controls the rotation speed of the motor itself.
Fully automatic washing machines use a DC brushless motor to pulse-width-modulate the line-to-line voltage applied to the stator windings, changing the speed several times between low-speed and high-speed operation, and drum-type washing machines. Some motors control the phase of the commutator motor so that a single motor can operate from low to high speeds.

0003

[Problem to be solved by the invention] In the above conventional example,
When using a single-phase induction motor, the motor itself does not have a speed change function, so a speed change means or deceleration means must be used. Therefore, there are problems in that noise is generated due to gear drive and the mechanical components become complicated. In addition, with a configuration in which the rotation speed is changed by controlling the phase of the commutator motor, if you want to obtain both torque at low speeds and high rotation at high speeds, you have no choice but to use a large and high output motor. This results in an increase in size and cost, and as a brush motor, there are problems such as noise generation due to brush friction noise that is inevitable, and the life of the brushes. Furthermore, when controlling the rotational speed of a DC brushless motor, simply applying pulse width modulation to the on-period of the line-to-line applied voltage pattern applied to the motor stator winding can only provide a speed ratio several times higher than that of a fully automatic washing machine. In order to obtain torque at low speed when a large speed change is required, such as in a machine, if you try to obtain the desired rotation speed and torque from low speed to high speed without a speed change means, you will have to use a large and high output motor. This made the washing machine unnecessarily large and expensive, making it impractical. In order to solve the above problems, the present invention aims to control the rotation of a DC brushless motor so that it can handle from low speed rotation to high speed rotation without using a speed change switching means.

0004

[Means for Solving the Problems] To achieve the above object, the present invention uses a DC brushless motor comprising a stator provided with windings and a rotor made of permanent magnets.
In a washing machine that rotates a rotary tank or stirring blade, the on-off duty ratio of the line-to-line applied voltage applied to the stator winding in a washing state such as dehydration, where the motor is rotated at high speed, is set so that the motor is rotated at low speed. The motor is characterized in that the rotation of the motor is controlled according to the washing state by duty control that is greater than the on-off duty ratio of the line-to-line voltage applied to the stator winding in washing states such as washing and rinsing. It is configured as a washing machine.

[0005]

[Operation] According to the present invention, in a washing machine that uses a DC brushless motor as the main motor for washing, dehydrating, etc.
In order to obtain a speed change of several tens of times from low speed for washing and rinsing to high speed for dehydration with one motor, the on/off duty ratio of the line-to-line voltage applied to the stator winding of the motor is adjusted between low speed rotation such as washing and dehydration. The rotation of the motor is controlled differently depending on when the motor rotates at high speeds such as During high-speed rotation, the on-off duty ratio is increased to increase the high-speed rotation range, and during low-speed rotation, the on-off duty ratio is decreased to reduce the input to the motor and lower the maximum rotation speed to achieve high torque. Furthermore, the rotational speed in the high-speed rotation region and the low-speed rotation region is controlled by pulse width modulating the line-to-line voltage applied to the stator windings.

[0006]

[Embodiment] Next, a specific example in which the present invention is applied to a drum type washing machine will be explained. Since drum-type washing machines have severe motor requirements, this configuration can be similarly applied to other fully automatic washing machines. First, the configuration of a drum-type washing machine will be explained using FIG. 6. For drum type washing machines, outer box 1
A water tank 2 is elastically supported inside by a spring 16,
A rotating tub 3 for storing laundry is housed inside the water tub 2, and a rotating tub horizontal shaft 4 fixed to its side plate is rotatably supported by the tub 2 via a bearing 15. The rotating tub 3 has a large number of small holes 6 formed on the entire surface of the peripheral wall 5 for the purpose of passing the washing liquid and discharging the dehydrated fluid, and a baffle plate 7 is provided on the peripheral wall 5 on the inner side parallel to the horizontal axis 4 of the rotating tub. It is installed to protrude towards. The rotary tub 3 is provided with an inlet 8 for loading and unloading laundry, and the inlet 8 is positioned upward when the rotary tub is stopped. The washing operation in this drum type washing machine involves loading the laundry into the rotating tub 3 from the input port 8, immersing it in the washing liquid supplied from the water supply pipe 10 into the water tub 2, and then rotating the rotating tub 3 at a low speed. Washing is performed by rotating. At this time, the laundry is pressed against the peripheral wall 5 by the centrifugal force generated from the rotation of the rotating tub 3, and is lifted up to near the top of the rotating tub 3 by the baffle plate 7, and then pushed to the bottom of the rotating tub 3 due to its own weight. It falls, and this action is repeated, and the laundry is washed by the impact force from the fall. In addition, the dehydration operation is
After draining the laundry liquid accumulated inside the water tank 2 through the drain pipe 17, by rotating the rotating tank 3 at high speed, the laundry is pressed against the peripheral wall 5 by centrifugal force, and the laundry liquid contained in the laundry is The washing liquid is discharged through the small hole 6 and the laundry is dehydrated. The rotation of the rotating tank 3 is transmitted from a DC brushless motor 11 (hereinafter referred to as a motor) to a rotating tank pulley 13 via a motor pulley 12 and a belt 14 . Regarding the motor 11, in order to lift the laundry immersed in the washing liquid during the above-mentioned washing, a large torque is required even at a low speed (approximately 400 rpm with a pulley ratio of 8) (up to approximately 38 kg/cm), and while a small torque (approximately 2.5 kg/cm) is sufficient during dehydration, high-speed rotation (approximately 8,000 rpm) is required. The configuration of this motor 11 will be explained with reference to FIG. This motor configuration is an example of the configuration used in this embodiment, and does not limit the present invention. The rotor's permanent magnet 18 is a ring-shaped ferrite material magnetized with eight poles, the rotor shaft 19 is rotatably supported by a motor case 21 via a bearing 20, and the stator 22 is arranged so as to form three phases. A winding is wound around the motor case 21, and the motor case 21 is fixed to the motor case 21. The rotation angle position of the rotor is detected by the magnetic force of the permanent magnet 18 by three Hall sensors 23.

Next, a method for controlling the rotation of the motor 11 will be explained with reference to the block diagram of the rotation configuration shown in FIG. The microcomputer 24 is operated with a constant voltage from a commercial power source 25 via a DC power source 26, and includes a load control circuit 27 that operates loads other than the motor, such as water supply valves and drain valves, and a display/operation section circuit 2.
8. Control the sensor circuit 29 such as the water level sensor and the lid switch. The motor 11 receives a DC voltage (DC 28 in this embodiment) generated by a motor DC power supply 30 from a commercial power supply 25.
2V) is distributed and controlled by the transistor module 31 and driven in three phases. The rotation angle position of the rotor of the motor 11 is detected by the Hall sensor 23, and the rotor position signal circuit 3
2, is inputted to the microcomputer 24, which outputs each base control signal of the three-phase transistor module 31 through internal arithmetic processing, and pulse width modulated by the PWM circuit 35 for rotation speed control. After being amplified by the base drive circuit 36, the transistor module 31 is driven.

Next, with reference to FIG. 3, a timing chart for generating base signals for each phase of the transistor module 31 based on rotor position signals through internal arithmetic processing of the microcomputer 24 will be explained. In this embodiment, the on/off duty ratio of the line-to-line applied voltage pattern applied to the motor stator winding is 1/3 at low speed and 1/2 at high speed. The rotor position signal is generated by three Hall sensors 23 placed at predetermined positions on the motor 11.
Accordingly, each pole of the permanent magnet 18 (in this embodiment, since there are 8 poles, one cycle is 90°) is detected. 3 Hall sensors 2
The rotor position signals from 3 are shown as (1), (2), and (3). The base control signal at low speed (indicated by a solid line) in CCW (counterclockwise direction) is the rotor position signal (1
) is turned ON when the signal falls, and then turned OFF after the rotor angle is maintained at 30°, so that the overall ON/OFF duty ratio becomes 1/3. Similarly, V
Phase and W phase are rotor position signals (2) and (3), respectively.
The output is controlled based on the falling edge of . Also, X, Y,
The output of the Z phase is similarly controlled based on the rise of the rotor position signals (1), (2), and (3). The on time of 30° at these rotor angles is actually a process of detecting the falling edge of the rotor position signal (2) and turning off, in the case of the U phase. Also, at high speed (
(denoted by a broken line), the rotor angle is controlled to turn on the output 15 degrees earlier than at low speeds, making the overall on-off duty ratio 1/2. Actually, in the case of the U phase, the rising edge of the rotor position signal 2 is used as the reference. C
The ON output timing of the W (clockwise) base signal is CCW.
In the case of , the falling reference becomes the rising reference, and the order of the U, V, W phases and the X, Y, Z phases is reversed at the off-output timing, and if the rising and falling criteria are reversed,
As shown in FIG. 3, motor characteristics similar to CCW can be obtained.

Next, the actually measured characteristics of the motor when driven according to the timing chart of FIG. 3 will be explained with reference to FIG. In the figure, points A and B are the operating points required by the drum-type washing machine, respectively. Also, the solid line shows the control characteristics at low speeds, and the broken line shows the control characteristics at high speeds. From FIG. 4, it can be seen that the control method at high speed satisfies both operating points A and B. However, the washing operating point of A is only the operating point when the rotary tub is started or when the laundry gets tangled.In actual operation, the torque is less than 1/3 of the maximum torque at 400 rpm, but at low speeds with low current consumption. If the control method is not used at high speeds, the current consumption will be large and the motor will generate too much heat, making it necessary to make the motor larger. If permanent magnets such as rare earth magnets are used, the magnetic force will be stronger and heat generation can be suppressed, but rare earth magnets are currently about 20 times more expensive than ferrite magnets, making it difficult to use them in home appliances due to the cost. The situation is difficult. Also, at point B during high-speed control, unlike in the washing operation, the load torque does not change once the rotating tank starts rotating, and after the rotational acceleration period, the torque required by the motor is reduced by the rotation mechanism. Since it is only due to friction, the current consumption is small even if the on/off duty ratio is reduced to 1/2, and there is no need to worry about motor heat generation. These are the important features of the present invention, which is an inexpensive magnet with weak magnetic force that can handle everything from low-speed large torque to high-speed rotation, despite its small size.
This is the reason why it can be driven without a gear changeover means.

Up to this point, motor driving has been explained using the timing chart shown in FIG. 3. Next, a method for controlling the rotational speed of the motor will be explained with reference to FIG. A in Figure 4
, each operating point of point B is within the range of the motor output mentioned above,
Although it has been explained that it is possible to drive the rotating tank, when operating at the actual set rotation speed, a motor output that passes through these operating points is required. Figure 5 is a waveform obtained by applying pulse width modulation to the output base signal shown in Figure 3, where A is approximately 2/3
The duty ratio B is about 1/3, and as shown in FIG. 5, if this duty ratio is decreased, the curve becomes lower left and the output decreases. While the motor 11 is being driven, the microcomputer 24 always detects the state of the rotor position signal shown in FIG. The duty ratio is controlled to increase/decrease so that the rotation time is /4 seconds (because one rotation takes four cycles). If the rotor position signal pulse is not input even after the calculated 1/4 second, the microcomputer 24 determines that the load is large and the rotation of the rotor is delayed, and increases the duty ratio of the next output base signal. do. Conversely, the calculated 1/
If a pulse is input before 4 seconds, the microcomputer 24 determines that the rotor is rotating too fast and reduces the duty ratio of the next output base signal. In this way, the motor always passes through the operating point of the load, so the set rotation speed of the motor is maintained despite fluctuations in the load torque. The above motor rotation speed control method does not limit the present invention, and if it is acceptable even if the rotation speed is slightly unstable without having to control every pulse of the output base signal, the motor rotation speed may be controlled once every second, for example. The duty ratio may be changed by a ratio of .

[0011]

[Effects of the Invention] As explained above, according to the present invention, the DC brushless motor is used as the main drive source for a washing machine that requires large torque during low speed rotation and also requires high speed rotation. By driving the motor using separate control methods, the rotor of the motor itself can be constructed from an inexpensive permanent magnet with low magnetic force, and the motor can be made smaller, which can greatly contribute to lowering the price and downsizing of washing machines. Particularly for drum-type washing machines, it is very effective because it does not cause the noise and life problems of commutator motors, and any rotational speed of the rotating tub can be obtained with a single motor.

[Brief explanation of the drawing]

FIG. 1 is a control circuit block diagram of a washing machine according to an embodiment of the present invention.

FIG. 2 is a pulse width modulation pattern diagram for motor rotation speed control.

[Fig. 3] Motor drive signal timing chart.

[Figure 4] Motor output characteristic graph.

[Figure 5] Graph of output characteristic changes due to motor pulse width modulation.

FIG. 6 is a configuration diagram of an example drum-type washing machine.

FIG. 7 is a configuration diagram of an example motor.

[Explanation of symbols]

3...Rotating tank 11...Motor 18...Permanent magnet (rotor) 22...Stator

Claims (2)

[Claims] [Claim 1] A washing machine in which a rotating tub or stirring blades are rotated by a DC brushless motor comprising a stator with windings and a rotor with a permanent magnet,
The on-off duty ratio of the line-to-line voltage applied to the stator winding in a washing state such as dehydration in which the motor rotates at high speed is different from the on-off duty ratio of the line-to-line applied voltage applied to the stator winding in a washing state such as washing or rinsing in which the motor rotates at low speed. A washing machine characterized in that the rotation of the motor is controlled according to the washing state by duty control that is greater than the on-off duty ratio of the line-to-line voltage applied to the line. 2. The washing machine according to claim 1, wherein the line-to-line voltage applied to the stator winding of the motor is pulse width modulated to control the rotational speed of the motor within the range of the washing state.