JPH0822353B2 - Load detection device for washing machine - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a load detection device for a washing machine, which determines a load amount based on a phase difference between voltage and current in a motor.

[Background of the Invention and its Problems]

In a washing machine, there has been proposed a device capable of automatically detecting the amount of cloth in order to select an optimum amount of water injection amount, detergent input amount or washing motor on / off duty ratio in accordance with the amount of cloth. As specific means therefor, there may be mentioned a method of judging the load amount from the magnitude of the motor current, a method of judging from the motor rotation speed, or a judgment method applying a capacitance type used in a digital weighing scale. .

However, the method of detecting current is likely to cause a large error due to voltage and frequency fluctuations of the power supply, and the method of detecting rotational speed or capacitance has many mechanical driving parts, so the structure is complicated and high accuracy is desired. There are no drawbacks.

[Object of the Invention]

It is an object of the present invention to provide a load amount detection device for a washing machine, which can detect the load amount with high accuracy and hardly receive an error due to a voltage or frequency fluctuation of a power source.

[Outline of Invention]

The present invention provides a phase difference detection unit that detects a phase difference between a voltage and a current of a winding in a motor by measuring respective zero-cross time differences, and a detected phase difference signal output from the phase difference detection unit. A phase comparison unit that compares a set value and outputs a determination signal when both are equal, and a time counting counter that measures the time from a predetermined time such as the start of energization of the motor to the time when the determination signal is generated, and The present invention is characterized in that a load amount judging section provided with a time length judging section for outputting a load quantity signal according to the time length measured by the counting counter is provided. Since the number is small, high-accuracy load amount detection can be expected.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 1, reference numeral 1 is a motor including a main winding 2, an auxiliary winding 3 and a condenser 4, for example, a washing motor, which drives an agitator in a washing tank. A phase detector 5 detects a phase difference between a voltage applied to the main winding 2 of the motor 1 and a winding current. The phase detector 5 can be easily realized by a circuit configuration that measures the zero-cross time difference between the winding current and the voltage. The phase comparison unit 6 detects the detected phase difference signal S1 output from the phase detection unit 5 and the reference phase setting unit 7
The determination signal S2 is output by comparing with the set value θ ₀ set in. The load amount determination unit 8 includes a clock counter 9 and a time length determination unit 10. Of these, the time counter 9 is for determining the time from the predetermined time (such as the start of energization) of the washing motor 1 to the output of the determination signal S2, that is, the rising time of the washing motor 1. belongs to. Further, the time length determination unit 10 uses the rising time signal S3 output from the time counting counter 9 and the reference values t ₁ , t ₂ and t ₃ set in the reference time setting unit 11 (however, t ₁ > t ₂ >
t ₃ ) for comparison. The motor control unit 12 receives the load amount signal S4 from the duration determination unit 10 and receives the washing motor 1
The intensity of the water flow is controlled by controlling the on / off duty ratio of the above according to the load amount. In this example, 1.4 seconds on, 0.9 seconds off for standard water flow, 1.7 seconds on, 0.6 seconds off for strong water flow, and 1.0 second for weak water flow.
Seconds are on and 1.9 seconds are off. Incidentally, 13 is an alarm device.

Next, the operation of the above configuration will be described with reference to FIGS. 2 to 5. The rotation speed N of the washing motor 1 is shown in FIG.
And the torque T and the phase difference θ are shown as actual measurement results. That is, 14 is a torque curve and 15 is a phase curve.
As shown by the phase curve 15, the phase difference θ between the voltage and the current in the main winding 2 of the washing motor 1 changes so as to increase gradually as the rotation speed of the washing motor 1 increases. This is considered to be because the primary exciting current remains unchanged while the secondary effective current increases as the load increases. Further, FIG. 4 shows the temporal change of the phase difference with the load amount as a parameter, and FIG. 5 shows the temporal change of the phase difference with the water amount as a parameter. The time in this case is the time elapsed from the start of energization of the washing motor 1.
In these figures, curve 16 is for small cloth load, curve 17 is for
Indicates a large cloth load amount, a curve 18 indicates a large water amount relative to the cloth amount, a curve 19 indicates a small water amount relative to the cloth amount, and θ ₀ is a set value set in the reference phase setting unit 7. 4 and 5, the phase difference between the winding voltage and the current of the washing motor 1 increases with time from the start of energization of the washing motor 1 with the rise of the rotation and reaches a constant value (saturation value). And its change over time, that is, the rising time, is the washing motor 1
It can be seen that the larger the load applied to, the longer it becomes.

In this case, the phase difference between the winding voltage and the current of the washing motor 1 is caused by the contact frictional force between the agitator and the cloth as the load, and increases as the cloth amount (load) decreases.
In particular, when the washing motor 1 starts to rotate, an acceleration force is added to the contact frictional force between the agitator and the cloth. Therefore, the smaller the amount of cloth, the more noticeable the phase difference between the winding voltage and the current of the washing motor 1. Appears in. Incidentally, when the rotation speed of the washing motor 1 reaches a saturation value, the phase difference between the winding voltage and the current of the washing motor 1 depends only on the contact frictional force between the agitator and the cloth. Does not appear so conspicuously.

Further, the set value θ ₀ is determined as follows. In the present embodiment, the phase difference between the winding voltage and the current of the washing motor 1 is detected to detect the rotation start-up which is prominently expressed by the cloth amount, so that the rise and the cloth amount when the cloth amount is large are It is necessary to detect any rising edge between the rising edge when it is small. Therefore, as shown in FIG.
_It is desirable that _{0 be} set to be slightly smaller than the saturation value when the cloth amount is large, and conversely, if the set value θ ₀ is set to be significantly smaller than this, the cloth amount detection time is short. However, since the phase difference corresponding to the cloth amount becomes small, the detection accuracy becomes poor. Therefore, the set value θ ₀ is determined to be a value that allows the amount of cloth to be quickly and accurately determined.

 Next, the operation will be described with reference to FIG.

As shown in Steps P _{1 to} P ₅ in FIG. 2, the washing time is set to start the washing operation, and then the washing motor 1 is driven to loosen it under the duty ratio which is the state of standard water flow. To start. This unraveling operation is performed for a time period in which the cloth is rotated several times, after which the washing motor 1 is temporarily cut off and the time counter 9 is reset to zero. This loosening action corrects the unevenness of the cloth, and then steps P6
~ As shown on page 9, wash motor 1 to start washing operation
Are energized again under standard water flow. At the same time, the phase detector 5 starts the detecting operation, and the clock counter 9 starts counting the time pulse. Then, the detected phase difference signal S1 output from the phase detection unit 5 is compared with the set value θ ₀ of the reference phase setting unit 7 in the phase comparison unit 6, and when these are equal, the determination signal S2 is output from the phase comparison unit 6 Is output. When this determination signal S2 is output, the time counting counter 9 stops the counting operation, and gives the rise time signal S3 of the washing motor 1 having the count value at that time to the time length determination unit 10. Reference value t ₁ of the time length determination unit 10 rise time signal S3 and the reference time setting unit 11, t _2, t ₃ compares the load signal S4
Is output. After this, if t ₂ <S3 <t ₁ , the motor control unit 2 controls the washing motor 1 so that a strong water flow is obtained as shown in steps P10 to P14, while t ₃ <S3, <t ₂ If the standard water flow proceeds from step P11 to P15, and willing to weak water flow in S3 <t ₃ if step P16. And S3> t ₁ if an excess load is temporarily stopped washing operation determined with operating giving alarm signal S5 to the alarm 13 as shown in step P17～P19, some of refilling or cloth by the user The washing operation is restarted after taking out.

Thus, according to the apparatus of this embodiment, the load amount, for example, the cloth amount is automatically determined by the phase difference detection in the early stage of the washing process, and the washing motor is controlled so that the cloth rotation speed becomes constant regardless of the cloth amount. 1 is controlled.
In this case, the phase difference between the winding voltage and the current of the washing motor 1 which is the detection target of the load amount determination is hardly affected by the voltage and frequency fluctuations of the power supply, so that the load amount can be detected with high accuracy. . Further, since the phase difference between the winding voltage and the current of the washing motor 1 is detected at the start-up of rotation of the washing motor 1, the amount of cloth can be promptly determined and the accuracy of the determination can be improved. It can be higher. Further, since the object to be detected is an electric element, it can be realized relatively easily by an electronic circuit such as a micro computer, so that it is easy to implement.

In the above embodiment, the strength of the water flow is automatically selected by the load amount signal, but the present invention is not limited to this, and the load amount signal is used to automatically determine the water injection amount. Alternatively, the washing operation time may be automatically selected according to the load amount signal.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention provides a load for a washing machine that can automatically and accurately determine a load amount related to a rotation start time of a motor by detecting a phase difference between a winding voltage and a current of the motor. A quantity detection device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration in one embodiment of the present invention, FIG. 2 is a flow chart, FIG. 3 is a phase and torque characteristic diagram with respect to the number of rotations of a motor, FIGS.
The figure is a characteristic diagram of the temporal change of the phase difference in which the cloth load amount and the water amount are used as parameters. In the figure, 1 is a motor, 5 is a phase detector, 6 is a phase comparator,
Reference numeral 7 is a reference phase setting unit, 8 is a load amount determination unit, 9 is a time counter, 10 is a time length determination unit, 11 is a reference time setting unit, and 12 is a motor control unit.

Claims (1)

[Claims] 1. A phase difference detecting section for detecting a phase difference between a voltage and a current of a winding of a motor by measuring respective zero-cross time differences, and a detected phase difference signal output from the phase difference detecting section. And a set value are compared and a judgment signal is output when both are equal, a time counter for measuring the time from a predetermined time such as the start of energization of the motor to the time when the judgment signal is generated, and A load amount detection device for a washing machine, comprising: a load amount determination unit having a time length determination unit that outputs a load amount signal according to a time length measured by a time counting counter.