JP2532415B2 - Load detection device for washing machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load amount detection device for a washing machine that detects the amount of clothes put in a washing tub, a dewatering tub, or a washing / dehydrating tub.

2. Description of the Related Art Conventionally, many load amount detecting devices of a washing machine for detecting a load amount have been provided. For example, there is a load detection device disclosed in Japanese Patent Publication No. 61-22598. As shown in FIG. 7, this load amount detecting device includes a washing motor 2 for selectively driving a stirring blade and a washing / dewatering tub, and switching means 4a, 4
It is connected to the AC power source 1 via b, and the capacitor 3 is connected between the windings of the washing motor 2. Switching means 4a, 4b is a signal is sent from the control circuit 5 to the gate G _1, G _2, on based on the signal to turn off. A current transformer 6 is connected to the motor 2, and the output of the current transformer 6 is input to the control circuit 5. And the control circuit 5 uses the switching means 4a, 4
The washing motor 2 is started by controlling b, the current value of the washing motor 2 after a fixed time thereafter is detected, and the load amount is determined by the current value. According to this configuration, the current value detected as the load amount data changes due to the voltage fluctuation of the power supply 1, so that the load amount cannot be accurately detected.

Therefore, a load amount determining device for a washing machine disclosed in Japanese Patent Laid-Open No. 57-136484 is provided. That is, this load amount determination device detects the power supply voltage and corrects and determines the load amount based on the fluctuation of the detected power supply voltage.

Problems to be Solved by the Invention However, in the conventional configuration, the change in the motor current or voltage at the start-up and startup of the motor is detected. The load amount could not be detected.
In other words, since the characteristics of this motor affect the motor current and voltage when the motor is energized, the conventional detection method that detects the load when the motor is energized detects the load accurately without being affected by the characteristics of the motor. It was impossible.

In view of the above problems, it is an object of the present invention to improve detection accuracy without being affected by variations in motor characteristics.

Means for Solving the Problems In order to achieve the above object, a load detection device for a washing machine according to the present invention includes a motor for driving a washing / dehydrating tub or a stirring blade, and a main coil and an auxiliary coil of the motor. A capacitor connected, a triac connected between the motor and an AC power supply, and a control means for controlling the energization of the motor via the triac, the control means energize the motor for a predetermined time, Immediately after that, the load amount is determined by the decay time of the capacitor voltage in the off period.

Operation With the above configuration, since the load amount is determined by detecting the decay time of the motor capacitor voltage when the motor is not energized, it is possible to prevent variations in detection accuracy due to variations in motor characteristics. When a command is given to the triac to stop the energization of the motor, it continues to be energized until the current of the AC power supply becomes zero due to the characteristics of the triac. Therefore, the capacitor voltage that is out of phase with the current of the AC power supply becomes a peak voltage when the current is zero, and the load amount can be detected with high accuracy by detecting the attenuation after reaching the peak voltage.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

As shown in FIG. 1, the control unit of the fully automatic washing machine in this embodiment is connected to an AC power source 1 and a washing motor 2 for selectively driving a stirring blade and a washing / dehydrating tub.
A condenser 3 is connected between the main coil and the auxiliary coil of the washing motor 2. Semiconductor switching devices 4a and 4b, which are one of switching devices, are connected between the terminals of the capacitor 3 and the AC power supply 1. Semiconductor switching device 4
The a and 4b are usually composed of bidirectional three-terminal thyristors (hereinafter referred to as triacs). When the triac 4a becomes conductive, the washing motor 2 rotates, and when the triac 4a is turned off and the triac 4b is turned on, the washing motor 2 is rotated in the reverse direction.
The control circuit 5A receives triacs 4a, 4b for driving the washing motor 2 and the drain valve magnet 7, triac 4c for driving the water supply valve 8 according to an instruction from the operation key, a signal from the lid switch 50, the water level detection device 5B, and the like. Controls 4d switching. The capacitor voltage detection circuit 9 detects the terminal voltage of the capacitor 3 of the washing motor 2. The terminal voltage of the capacitor 3 has a correlation with the motor rotation speed, and the capacitor voltage decays according to the rotation speed during the rest period before the triac 4a or 4b is made conductive and then the rotation is reversed. FIG. 2 shows a triac 4a for driving the washing motor 2.
Or, it shows the change of the terminal voltage of the capacitor 3 when 4b is turned off. In the figure, A indicates a case where the load amount is small and the reduction rate of the motor rotation speed is small, and B indicates a case where the load amount is large and the motor rotation speed rapidly decreases. During the suspension period of the forward / reverse rotation control of the washing motor 2, the triac 4
Since both a and 4b are off, the voltage across the terminals of capacitor 3 is 0.
However, since the washing motor 2 is rotated to drive the stirring blades before the rest period, the inertia of the washing motor 2 causes the washing motor 2 to continue to rotate and an induced voltage is generated in the main coil and the auxiliary coil. The voltage decreases and the waveform becomes as shown in FIG. When the load amount is large, the motor speed rapidly decreases and the capacitor voltage also decreases, so that the load amount such as the cloth amount can be detected. Moreover, even if an off command is output to the triac, the triac has a characteristic that the energized state is maintained until the current of the AC power supply 1 becomes zero. Therefore, even if an off command is issued to the triac, the motor 2 continues to be energized until the AC power supply 1 becomes zero, so that the terminal voltage of the capacitor 3 of the motor 2 reaches the peak voltage. In other words, the voltage between the terminals of the capacitor 3 deviates from the phase of the current of the AC power supply 1 by 90 degrees, so the peak voltage is reached when the current of the AC power supply 1 becomes zero, and the timing of stopping the energization of the AC power supply 1 Even when the timing of issuing the off command to the triac does not reach the time when the current of the AC power supply 1 reaches zero, the inter-terminal voltage of the capacitor 3 always reaches the peak voltage. Therefore, after reaching this peak voltage, the capacitor 3 is discharged. After the start, the induced voltage gradually decreases, so that the voltage waveform shown in FIG. 2 is obtained. In this way, since the attenuation after the voltage across the terminals of the capacitor 3 reaches the peak voltage is always detected, the detection accuracy can be improved.

A third embodiment of the terminal voltage detection circuit 9 of the capacitor 3
Shown in the figure. In FIG. 3, a resistor 90 and a full-wave rectifier circuit 91 are connected in series between the terminals of the capacitor 3, and a photo coupler 92 is connected between the DC output terminals of the full-wave rectifier circuit 91 to electrically insulate them. Connect a series body of a resistor 93a and a base-emitter resistor 93b to the emitter terminal of the phototransistor, which is the output side of the photocoupler 92.
The base of the transistor 94 is connected to the connection point of 3b. The resistor 95 connected to the collector of the transistor 94 and the collector terminal of the photocoupler 92 are connected to the DC power supply terminal Vcc. A capacitor 96 is connected between the collector and the emitter of the transistor 94, and the terminal voltage V ₀ of the capacitor 96 is applied to the control circuit 5A.

FIG. 4 shows the waveform of each part of the capacitor voltage detection circuit 9 having the above-mentioned configuration. In FIG. 4, Vc is the capacitor 3
, Ve is the output voltage of the photocoupler 92, and V ₀ is the terminal voltage of the capacitor 96. At time t ₀ in the figure, the triac 4a or 4b is turned off, the capacitor voltage Vc decreases according to the rotation speed of the motor 2, and the photocoupler output voltage
Ve also decreases. The output voltage V ₀ rises when the capacitor voltage Vc approaches zero, and changes from Lo level to Hi level during the period t ₁ . Measure the time T ₁ (t ₁ −t ₀ ), and determine the load amount based on the magnitude of T ₁ .

Next, the outline of the load amount detection method will be described with reference to FIGS. 5 and 6. In FIG. 5, various parameters are initially initialized and the water level is set to low at the same time (501).
Start water injection by opening the water supply valve (502). Water injection is continued until the set water level is reached (503), and when the set low water level is reached, washing is started (504). At this time, the normal rotation-pause-reverse-pause-normal rotation control of the washing motor 2 is controlled by 10 to several.
10 cycles Repeated load is detected. That is, the second
The amount of cloth is judged according to the size of time T ₁ shown in the figures and FIG. 4 (505). The cloth amount determination executed during the reversing cycle of the washing motor 2 will be described with reference to FIG. First, the time
T ₁ and T ₂ are incremented (506), and a flag determination as to whether the motor 2 is on or off is made (507). When the motor 2 is on, the motor on time ton is determined in step 508, and when the predetermined time is reached, the motor is turned off in step 509 and the time parameters T ₁ and T ₂ are cleared. When the motor 2 is stopped, it is determined in step 510 whether the output voltage V ₀ of the capacitor voltage detection circuit 9 is Hi or Lo, and V ₀ changes from Lo to Lo.
The amount of load is judged by the magnitude of time T ₁ when it changes to Hi. When T ₁ is small and the load amount (cloth amount) is large, the washing time is lengthened, the water level is changed from low to high, and the water flow is strengthened. On the contrary, if T ₁ becomes longer, washing time,
Control rinsing time, dehydration time, etc. shortly.

Although the example of measuring the decay time by the capacitor voltage of the motor is shown in the present embodiment, the decay time of the motor rotation speed or the decay time of the coil voltage of the motor correlated with the motor rotation speed may be measured. The point is to use a parameter that correlates with the rotation speed of the motor. In addition, the load amount may be determined by the decay time of the rotation of the washing / dehydrating tub without measuring during the down time of the stirring blade of the washing motor. In this case, if the load amount is large, the decay time is long and If the amount is small, the decay time becomes short.

EFFECTS OF THE INVENTION As is apparent from the above embodiments, according to the present invention, the amount of load is detected by measuring the decay time of the capacitor voltage of the motor immediately after the motor is driven for a certain period of time and turned on and off. Is not affected by variations in the characteristics of
It is possible to detect the load amount with high accuracy. Moreover, if a command is given to the triac to stop energizing the motor,
Due to the characteristics of the triac, the current continues to be supplied until the current of the AC power supply becomes zero, so it is possible to detect the attenuation after the capacitor voltage reaches the peak voltage, and it is possible to improve the load amount detection accuracy due to the attenuation. . Then, it becomes possible to control the water flow, the washing time, and the rinsing time according to the accurate load amount, which enables more advanced control.

[Brief description of drawings]

FIG. 1 is a block diagram showing a load amount detecting device for a fully automatic washing machine and its control circuit according to an embodiment of the present invention, and FIG. 2 shows a change in capacitor terminal voltage immediately after driving a motor to turn it off. Fig. 3 is a circuit diagram of the capacitor terminal voltage detection circuit, Fig. 4 is a waveform diagram of each part of the capacitor terminal voltage detection circuit, and Figs. 5 and 6 are flowcharts showing control of the load amount detection device, FIG. 7 is a block diagram of a conventional load amount detecting device. 1 ... AC power supply, 2 ... Washing motor, 3 ... Capacitor, 4a-4d ... Switching device, 5A ... Control circuit.

Claims (1)

(57) [Claims] 1. A motor for driving a washing / dehydrating tank or a stirring blade, a capacitor connected between a main coil and an auxiliary coil of the motor, and a triac connected between the motor and an AC power source, The washing machine is provided with a control means for controlling energization to the motor through a triac, the control means energizes the motor for a predetermined time, and determines a load amount by a decay time of the capacitor voltage within an off period immediately after that. Load amount detection device.