JPH01185289A - Load detector for washing machine - Google Patents

Abstract

PURPOSE:To detect load with a simple circuit without using a high precision voltage detecting circuit by ON/OFF controlling a washing motor with a switching unit, and detecting load based on signals from a voltage detection circuit during OFF operation of the washing motor. CONSTITUTION:Output terminal wave between motor control thyristers 220a, 220b at the OFF time of a washing motor 3 is indicated, and a thyrister output voltage Vc is attenuated as the number of revolutions of the motor 3 decreases. A voltage detection circuit 23 outputs the signal Vc pulse-converted from the voltage Vc. The pulse of voltage Vc can be detected by detecting the number of up and down edges of this Vc. In a timing chart ON/OFF controlling the thyristers 220a, 220b alternately for detecting load, a thyrister Tr1 turns ON/OFF three times, and a thyrister Tr2 turns ON/OFF three times to perform inverse- control, where T1 is ON period and T2 OFF period. This operation is repeated several times to count-add the pulse Vc at the time of motor OFF (T2 period) so as to judge load of articles to be washed according to the number of pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a washing machine load detection device useful for controlling the amount of water supplied, the amount of detergent during washing, etc. according to the amount of laundry.

2.-- Prior Art Various types of devices have been proposed as load amount detection devices for washing machines.

As an example, as shown in Japanese Unexamined Patent Publication No. 62-176492, a proposal has been made to detect the back electromotive force when the motor is turned off, detect the rotation of the motor based on the motor back electromotive force, and control the amount of water supplied.

Problems to be Solved by the Invention However, in the method disclosed in JP-A-62-176492, when the motor is turned off, it is thought that a back electromotive force is generated due to its inertial force, but the back electromotive force is very small.
It is very difficult to detect the back electromotive force. That is, when the motor on/off means is turned off with the motor coil and AC power supply connected in series, the following formula holds true.

AC voltage vAc=vM (motor voltage) +vs (motor on/off means terminal voltage) Here, vAa is constant and the motor on/off means is almost infinite, so VAC you vs. Yo37,-
1, -VM (motor voltage) can hardly be detected, and a very high-precision voltage detection circuit must be used to detect the back electromotive force depending on the load amount.

In view of the above problems, it is an object of the present invention to detect a signal corresponding to the rotation when the motor is off with a simple configuration.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a washing motor that rotationally drives an agitation blade, a capacitor connected between the windings of the washing motor, and at least one that controls the washing motor in forward and reverse directions. It includes two switching devices, a control means for controlling on/off of the switching devices, and a voltage detection circuit connected between the output terminals of the two switching devices, and the control means periodically controls the washing motor by the switching device. The washing motor is configured to perform on/off control and detect the load amount based on the signal from the voltage detection circuit during the washing motor off period.

Function: The voltage detection circuit detects the voltage of the capacitor. When the motor is off, the voltage charged in the capacitor attenuates, and the attenuation time or the number of generated voltages attenuates in accordance with the rotation of the motor. In other words, if the motor rotation is zero, the capacitor voltage will momentarily attenuate through the motor coil, but if the motor is rotating, the capacitor energy will not disappear due to the back electromotive force, but will gradually attenuate.
The attenuation rate of motor rotation can be detected, and the amount of load can be detected.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a fully automatic washing machine control device according to the present invention. That is, 1 is an AC power supply that applies an AC voltage to the control device 2. The control device 2 includes a washing motor 3 that rotationally drives an agitating blade, and its phase advancing capacitor 4. It has a switching device 22 for driving and controlling a water supply valve 5 for supplying water into the washing tub and a drain magnet 6 for driving a drain valve for draining water from the washing tub. 7 is a safety switch that stops dehydration when the lid is opened during dehydration, and 8 is a water level detection device that converts the water level into an electrical signal. The control device 2 is composed of a control circuit 2Q consisting of a microcomputer, its peripheral circuits, a DC power supply, etc., and an operation display device 21 and a switching device 22 consisting of a display device, key switches, etc. The switching device 22 consists of a bidirectional three-terminal thyristor (hereinafter referred to as a thyristor). The voltage detection circuit 23 is connected to the washing motor 3. of the switching device. Drive output terminal v1. V2 and shapes the terminal voltage VC into a signal V. is added to the control circuit 20.

FIG. 2 shows a specific embodiment of the voltage detection circuit 3.

Cyrisk 2202L, which controls the forward and reverse rotation of the motor 3,
A series connection body of a resistor 230, an input terminal of a photocoupler 231, and a diode 232 is connected between T2 terminals V1-V, 2 of 220b. Resistors 233 and 234 and the base terminal of an NPN run risk 235 are connected in series to the output terminal of the photocoupler 231. NPN) Connect the load resistor 236 to the colo-7 collector terminal of the run risk 235, and output the output signal vc.
The relationship between the input voltage VC and the input voltage VC is as shown in FIG. 3(&)(b). FIG. 3 (?L) shows the output terminal waveform between the motor control thyristors 220 & 22Ob when the washing motor is off, and as the rotational speed of the washing motor 3 decreases, the thyristor output voltage VC also attenuates.

A voltage detection circuit that inputs this voltage Vc outputs a signal v (H) which is a pulse of the voltage VC.
(The pulse of the voltage Vc can be detected by detecting the number of rises and falls of H. 9 is a choke for protecting the surge current of the thyristor.

Figure 3 shows an Iristor 220J220 for load detection.
A timing chart for alternately controlling on/off control of b is shown. When the T1 period is on and the T2 period is on, the thyristor Tr4 is turned on and off three times, and then the thyristor Tr2 is turned on and off three times to perform inversion control. - Repeat this several times, count and add the pulses VQ when the motor is off (period T2), and determine the amount of laundry based on the number of pulses.

FIG. 4 is a flowchart of load amount determination.

7 bae.

After setting the initial value in step 201, it is determined in step 202 whether or not the normal reversal of the motor for determining the amount of cloth has been completed based on the number of times N of motor on/off. In step 203, the number of normal rotations or reverse rotations of the motor is counted, and the normal/reversal control flag is changed. Steps 205 and 2.06 are motor-on control, and when the motor-on time period has elapsed, step 2.
The motor is turned off at step 07, and the pulses are counted and added at step 208. When the motor off period T2 has elapsed, the motor forward/reverse control counters n and N are incremented and the state returns to the initial state. Motor on/off number N is 2
When the fourth time is reached, the process moves to the cloth amount determination loop 211. 'r,,
'r2 The time limit is approximately 0.3 to 0.8 seconds. If the motor is reversed in the normal direction only once, there will be a large error in determining the amount of cloth, so one cycle of turning on and off three times to the right and three times to the left is repeated for 4 cycles, and the pulses when the motor is turned off are added and accumulated to determine the amount of cloth. do. If the number of pulses is large, the amount of laundry is small, and the water level in the washing tub, amount of detergent, washing time, and spin-drying time can be set to be small.

Effects of the Invention As is clear from the above embodiments, according to the present invention, in order to detect the output terminal voltage of a switching device for forward/reverse control of a washing motor, a voltage correlated to the damping rate of the motor, which could hardly be detected in the past, can be detected. The voltage can be detected, and the load amount can be detected using a circuit with a simple configuration without using a highly accurate voltage detection circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a washing machine load detection device according to an embodiment of the present invention, Fig. 2 is a circuit diagram of a voltage detection circuit for detecting the load, and Fig. 3 is a waveform diagram of each part of the same. FIG. 4 is a timing chart showing an embodiment of a washing motor control method for detecting the same load amount, and FIG. 5 is a flowchart for detecting the same load amount. 2...control device, 3...washing motor,
4...Capacitor, 2o...mountain/control a times M,
22...Switching device, 23...
Voltage detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person C%3c'J faction

Claims (1)

[Claims] a washing motor for rotationally driving an agitating blade; a capacitor connected between windings of the washing motor; at least two switching devices for controlling the washing motor in forward and reverse directions; a control means for controlling on/off of the switching device; 2
The control means includes a voltage detection circuit connected between two switching device output terminals, and the control means periodically controls on/off of the washing motor by the switching device, and controls the voltage detection circuit based on the signal of the voltage detection circuit during the washing motor off period. A load amount detection device for a washing machine characterized by detecting a load amount.