JP3125308B2 - Washing machine load detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detecting device for a washing machine for detecting an amount of laundry such as clothes put in a washing and dewatering tub (hereinafter referred to as a washing tub).

[0002]

2. Description of the Related Art In recent years, a load detecting device for a washing machine for detecting the amount of laundry put into a washing tub has been required to have improved detection accuracy.

Conventionally, there have been provided a large number of load detecting devices for a washing machine of this kind, for example, Japanese Patent Publication No. 61-225.
No. 98 is disclosed. Hereinafter, the configuration will be described with reference to FIG.

As shown in the figure, a motor 1 selectively drives a washing tub or a stirring blade (neither is shown), and is connected to an AC power supply 3 via switching means 2a and 2b. The capacitor 4 for leading the phase is connected. A signal is sent from the control means 5 to the gates G1 and G2, and the switching means 2a and 2b are turned on and off based on the signal. The motor 1 has a current transformer 6
Are connected, and the output is input to the control means 5. The control means 5 includes switching means 2a, 2b
, The motor 1 is started, and the current value of the motor 1 after a certain period of time is detected, and the load amount is determined based on the current value.

[0005]

In such a conventional load detecting device for a washing machine, since the current value of the motor 1 is affected by a decrease in the belt tension due to the repetition of washing, the variation in the detection of the load is reduced. There was a problem of becoming large. Further, the reference value for determining the water level according to the load amount has to consider this detection variation, so that there is a problem that it is difficult to determine the reference value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to accurately detect a load amount by correcting a change in a damping rate of a back electromotive voltage of a motor due to a decrease in belt tension.

[0007]

According to the present invention, there is provided a motor for driving a washing / dewatering tub or agitating blade, a control means for controlling power supply to the motor, and a memory for storing the number of washing times. Washing number storage means to perform, the control means determines the amount of load in the washing and dewatering tub based on the attenuation rate of the back electromotive voltage of the motor during the rest period after energizing the motor for a required time, and The problem solving means is that the load amount can be changed by a value stored in the washing number storing means.

[0008]

According to the present invention, the load can be detected by correcting the increase in the back electromotive voltage of the motor due to the decrease in the belt tension due to the increase in the number of washings. Can be reduced, and the detection accuracy can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The same components as those in the conventional example are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 1, a washing tub 7 is rotatably disposed in an outer tub 8, and a stirring blade 9 is rotatably disposed at an inner bottom thereof. The washing tub 7 and the stirring blade 9 are selectively switched by the mechanical case 10, and the rotational force of the motor 1 is transmitted by the belt 11. The control means 12 includes bidirectional thyristors 2 a and 2 b as switching means for driving the motor 1, a drain valve magnet 15, a water supply valve, in accordance with an instruction from an operation key, a signal from a power switch 13, a water level detection means 14, and the like. 16 for controlling the two-way thyristors 2c and 2d, respectively. When the bidirectional thyristor 2a is turned on, the motor 1 rotates forward, and when the bidirectional thyristor 2a is turned off and the bidirectional thyristor 2b is turned on, the motor 1 rotates reversely. Capacitor voltage detection circuit 17
Is for detecting the terminal voltage of the phase-advancing capacitor 4 of the motor 1, and its output is input to the control means 12. The number-of-times-of-washing storage means 18 is linked with the power switch 13 and stores the number of times of washing, and outputs its output to the control means 12. The control means 12 includes a capacitor voltage detection circuit 17
The load in the washing tub 7 is determined based on the attenuation rate of the back electromotive voltage of the motor 1 during the rest period after the motor 1 is energized for a required time by the output of
Can be changed by the stored value.

In the above configuration, the operation will be described with reference to FIGS. 3 to 5. The terminal voltage of the capacitor 4 has a correlation with the rotation speed of the motor 1, and the bidirectional thyristor 2a
Alternatively, the terminal voltage of the capacitor 4 attenuates in accordance with the rotation speed of the motor 1 during a rest period before turning on 2b and then reversing the rotation. That is, during the idle period of the normal rotation and the reverse rotation of the motor 1, the terminal voltage of the capacitor 4 becomes 0 because both the bidirectional thyristors 2a and 2b are off.
Since the motor 1 is rotated to drive the stirring blade 9 before the suspension period, the motor 1 continues to rotate by inertia, and induces back electromotive force in the main coil and the auxiliary coil, and this back electromotive voltage decreases the number of rotations. And the waveforms as shown in FIGS. 3 (a) and 3 (b). FIG. 3A shows a case where the load is small and the decrease in the number of revolutions of the motor 1 is small, and FIG. 3B shows a case where the load is large and the number of revolutions of the motor 1 is rapidly reduced. When the load amount is large, the rotation speed of the motor 1 rapidly decreases and the terminal voltage of the capacitor 4 also decreases, so that the load amount such as the cloth amount can be detected. That is, the load amount is determined by measuring the decay time of the capacitor voltage (T _1a , T _{1b in} FIG. 3), the change rate of the capacitor voltage, or the decay rate such as the number of voltage waveforms.

Next, after detecting the load, the control means 12 sets a high, medium, low, and small reference value for determining the water level so as to match the large, medium, low, and small load, respectively. Water is supplied into the washing tub 7 based on the reference value and the output of the water level detecting means 14. Here, as shown in FIG. 4, when the tension of the belt 11 fluctuates, the number of waveforms of the capacitor voltage with respect to the load amount changes. On the other hand, the tension of the belt 11 changes as shown in FIG. Therefore, the change in the tension of the belt 11 shown in FIG. 4 is replaced by the number of washings, and when the number of washings stored in the washing number storage means 18 becomes n ₁ or n ₂ , the variation a of the number of capacitor voltage waveforms a
By ₁ ~a _4, b ₁ ~b ₄ corrects the load.

In the above embodiment, the load is determined based on the rotation reduction rate of the stirring blade 9, but the load may be determined according to the rotation reduction rate of the washing tub 7. In this case, the load is determined. The larger the amount, the longer the decay time, and the smaller the load, the shorter the decay time. Conversely, the rate of change of the voltage decreases when the load is large, and increases when the load is small. Further, instead of detecting the capacitor voltage, the current value of the capacitor may be detected.
What is necessary is just to detect a current value.

[0014]

As is apparent from the above embodiments, according to the present invention, a motor for driving a washing tub or a stirring blade, a control means for controlling energization of the motor, and a washing machine for storing the number of washing times. Number control means, wherein the control means determines the load amount in the washing tub based on the decay rate of the back electromotive voltage of the motor during a rest period after energizing the motor for a required time, and Since the change can be made by the stored value of the washing number storage means, the load amount detected by the back electromotive voltage of the motor can be corrected by the fluctuation of the belt tension due to the number of washing times, the detection variation of the load amount can be reduced, and the detection accuracy can be improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a load detection device for a washing machine according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a washing machine provided with the load amount detection device.

FIG. 3 is a waveform diagram of a capacitor terminal voltage of the load amount detection device.

FIG. 4 is a characteristic diagram of the load amount and the number of capacitor voltage waveforms using the belt tension of the load amount detection device as a parameter.

FIG. 5 is a characteristic diagram showing the relationship between the number of washings of a general washing machine and belt tension.

FIG. 6 is a block circuit diagram of a conventional load detection device for a washing machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 7 Washing tub (washing and dehydrating tub) 9 Stirrer blade 12 Control means 18 Washing number storage means

Claims (1)

(57) [Claims] 1. A motor for driving a washing and dewatering tub or a stirring blade, control means for controlling power supply to the motor, and washing number storage means for storing the number of washing times, wherein the control means includes the motor The amount of load in the washing and spin-drying tub is determined based on the attenuation rate of the back electromotive voltage of the motor during the rest period after energizing for a required time, and the amount of load can be changed by the stored value of the number of washing times storage means. Load detecting device for washing machine.