JPS6259599B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load amount determination device for a washing machine that is capable of automatically detecting the amount of water or cloth in a tub.

Conventionally, as methods for automatically detecting the amount of load on a washing machine, there are a method of detecting the length of the rise time of the rotational speed of the motor and a method of detecting the rate of change of the load current of the motor. Among these, the former, which uses the rotational speed as a detection element, requires a proximity switch or a tachometer generator, resulting in a complicated structure. Further, when the power supply voltage changes, the rise time of the rotational speed also changes, resulting in inaccurate detection accuracy. On the other hand, in the latter case, which uses the motor load current as a detection element, the detection accuracy is low even if the structure is simple. That is, as shown by the load current curve I _L in FIG. 3 according to the embodiment, when the rotation speed N is low, the change in the rotation speed N is as large as approximately 1000 RPM for a 10% change in the maximum load current. Therefore, detection accuracy becomes low. Furthermore, when the load current is used as a detection element, it is necessary to remove the large load current at the time of startup from the detection element, which complicates the configuration of the electric circuit. On the other hand, the auxiliary winding voltage of a capacitor motor, which is a washing machine motor, is as shown by the auxiliary winding voltage curve V _A in Figure 3. The small speed of approximately 500 RPM improves detection accuracy. However, since a capacitor motor is periodically rotated in forward and reverse directions to generate a reverse water flow, the winding that acts as an auxiliary winding also periodically becomes the main winding, and simply the auxiliary winding voltage is used as the detection element. It is not possible.

In addition, in FIG. 3, T is a torque characteristic curve.

The present invention was made in view of the above circumstances, and its purpose is to improve load detection accuracy by using the winding voltage of the capacitor motor as a detection element, and to alternately connect the windings of the capacitor motor to the auxiliary windings. To provide a load amount determination device for a washing machine that can detect the load amount without making a judgment while functioning as a washing machine.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.
This will be explained with reference to the figures. Reference numeral 1 denotes an AC power supply, which supplies power to the washing mechanism section 2 and also to a DC power supply circuit 5 via a transformer 3 and a full-wave rectifier circuit 4. This DC power supply circuit 5 consists of smoothing capacitors 6 and 7 and a constant voltage circuit 8, and in order to serve as a DC power supply for electronic circuits, it has a reference potential terminal 9 with positive polarity, a constant voltage terminal 10 with negative polarity, and a power supply voltage (AC A non-constant voltage terminal 11 that depends on fluctuations in the voltage of the power supply 1 is derived. The washing mechanism section 2 includes a condenser motor 12 which is a washing machine motor, a water supply valve 13 and a drain valve 1.
4, these are bidirectional thyristors 1
5, 16, 17, and 18, the washing machine is controlled in the same way as a normal washing machine based on commands from the control circuit 19. The capacitor motor 1
2 consists of a first phase winding 12a, a second phase winding 12b, and a capacitor 12c arranged at an electrical angle of 90 degrees, and thyristors 15, 1
6 constitutes an automatic reversing circuit 20 that alternately causes the first phase winding 12a and the second phase winding 12b to act as auxiliary windings in order to periodically rotate the capacitor motor 12 in forward and reverse directions during washing or rinsing operations. There is. Here, the auxiliary winding refers to a winding to which power is applied via the capacitor 12c.

Next, the load amount determination means includes first and second reference value setting circuits 21 and 22, and the first reference value setting circuit 21 connects the non-constant voltage terminal 11 to the constant voltage diode 2.
Similarly, the second reference value setting circuit 22 consists of resistors 26 and 27 to which a voltage is applied via Vs. The reference value Vs fluctuates depending on the voltage fluctuation of the AC power supply 1, but the rate of change is larger than that of the AC power supply 1 because it includes the constant voltage diode 23. The above reference value Vs is the first and second comparator circuit 2.
It is designed to be applied to non-inverting input terminals 8 and 29. The first input circuit 30 receiving the load amount detection element is connected to the first phase winding 12 of the capacitor motor 12.
A second input circuit 33 divides the terminal voltage of the second phase winding 12b and outputs the winding voltage Vb. It consists of resistors 34 and 35,
These winding voltages Va and Vb are determined by comparator circuits 28 and 2.
9 inverting input terminals, respectively.

Half-wave rectifier diodes 36 and 37 are connected in parallel with the resistors 32 and 35, respectively. Next, to explain the time difference detection means 38, 39 is a first waveform shaping circuit, 40 is a second waveform shaping circuit, and these are the first and second comparison circuits 2.
It has the function of inverting the polarity of the outputs of 8 and 29 and converting them into DC signals. First waveform shaping circuit 39
are resistors 41, 42, 43, 44, capacitor 4
5, a diode 46 and an operational amplifier 47, and the second waveform shaping circuit 40 includes a resistor 48,
49, 50, 51, a capacitor 52, a diode 53, and an operational amplifier 54. The input side circuit networks of both operational amplifiers 47 and 54 are supplied with power from the constant voltage terminal 10. Further, the outputs of the operational amplifiers 47 and 54 are applied to the control circuit 19 via an exclusive OR circuit 55.

Next, the operation of the above configuration will be explained. The washing operation itself is similar to the known one, in which the thyristors 15 to 18 are controlled on and off by the gate signal from the control circuit 19, and operations such as washing, rinsing, water supply and drainage, etc. are performed. In the rinsing process, the thyristors 15 and 16 are turned on alternately, so that the capacitor motor 12
is periodically rotated forward and backward to generate a reversed water flow. In this case, when the thyristor 15 is turned on, the full voltage of the AC power source 1 is applied to the first phase winding 12a and acts as a main winding, but the voltage is applied to the second phase winding 12b via the capacitor 12c. When the thyristor 16 is turned on, the first phase winding 12 acts as an auxiliary winding.
a acts as an auxiliary winding, and second phase winding 12b acts as a main winding.

Now, the load amount detection operation will be explained with reference to FIG. 2. In FIG. 2, A is the on/off mode of the thyristor 15, and B is the on/off mode of the thyristor 16. In the initial stage of washing, if the thyristor 15 is turned on at time _T0 , the terminal voltage of the first phase winding 12a, which has become the main winding, immediately rises to the power supply voltage, so the first input circuit 30 divides the voltage. The resulting winding voltage Va is shown in Figure 2C.
It becomes a rising waveform. On the other hand, since the terminal voltage of the second phase winding 12b, which has become an auxiliary winding, gradually rises as the rotation speed increases, the second input circuit 33
The winding voltage Vb divided by 2 has a waveform shown in FIG. 2D. The actual waveforms of these two winding voltages Va and Vb are shown by the dotted lines in FIG.
37 results in a half-wave rectified waveform. Now, these two winding voltages Va and Vb are simultaneously compared with the same reference value Vs by comparison circuits 28 and 29, and when Va>Vs and Vb>Vs, the comparison circuit 28 and 29
The outputs of 8 and 29 become low level. In this embodiment, the output of the first comparison circuit 28 becomes low level at time _T0 , and the output of the second comparison circuit 29 becomes low level at time T0.
At T ₁ it becomes low level. The moment the outputs of the comparison circuits 28 and 29 become low level, the diode 4
Since the cathode potentials 6 and 53 become approximately the same potential as the reference potential terminal 9, the outputs of the operational amplifiers 47 and 54 become high level. That is, as shown in FIG. 2E, the output signal _S1 of the operational amplifier 47 is inverted to a high level at time _T0 , and the output signal S2 of the operational amplifier 54 is inverted to a high level at time _T1 . These output signals S1 and S2 are waveform-shaped into DC signals by the action of capacitors 45 and 52. As mentioned above, the two output signals S1 and S2 outputted from the operational amplifiers 47 and 54 are given to the exclusive OR circuit 55, so that the exclusive OR circuit 55 generates a pulse-like time difference signal as shown in FIG. 2G. S3a is at time T ₀ -
It is output during T ₁ and given to the control circuit 19.

The explanation so far has been about the action during forward rotation in which the thyristor 15 is turned on and the second phase winding 12b acts as an auxiliary winding, but the thyristor 16 is turned on and the first phase winding 12a acts as an auxiliary winding. When the rotation is automatically reversed, contrary to the above, the winding voltage Va gradually rises and the winding voltage Vb immediately rises, so the exclusive OR circuit 55 outputs the time T. Pulse time difference signal S3 between ₀₁ and T ₁₁
b is output. Incidentally, _T2 in FIG. 2 represents the time when the first and second phase windings 12a and 12b are cut off immediately before automatic reversal. The pulse width of the time difference signals S3a and S3b obtained in this way is the same as that of the first and second phase windings 12 when acting as auxiliary windings.
Since it depends on the rise time of a and 12b, that is, the load amount such as the amount of water in the tank and the amount of cloth, it becomes a load amount detection signal. The control circuit 19 that receives the time difference signals S3a and S3b stores the information, and based on the storage, performs additional water supply, washing time control, etc. in accordance with the load amount. It is desirable that the above-described load amount detection operation be performed during the first automatic reversal cycle or several cycles of washing or rinsing.

By the way, even if the power supply voltage fluctuates during the load amount detection operation as described above, the reference value Vs also changes depending on this fluctuation, so the time difference signals S3a, S3
The pulse width of b is not changed by fluctuations in the power supply voltage.

Note that the present invention is not limited to the above-described embodiments, and the AND output of the output signals S ₁ and S ₂ from the waveform shaping circuits 39 and 40 is controlled by the microcomputer in the control circuit 19 to the thyristor 15. ,1
The time difference information may be obtained by comparing with the turn-on timing signal No. 6.

As described above, according to the present invention, the proximity switch,
There is no need for a tachogenerator or a circuit that excludes the load current at startup from the detection element, thereby simplifying the mechanical and electrical configuration. In addition, the detection accuracy improves because the first and second phase winding voltages have a small rate of change with respect to the load amount, and the reference value also depends on fluctuations in the power supply voltage, so the detection accuracy decreases due to fluctuations in the power supply voltage. Furthermore, even though the two phase windings are controlled so that they become auxiliary windings alternately, the terminal voltages of both windings are finally compared with each other, so the auxiliary winding determination circuit is is no longer necessary, and the circuit configuration can be expected to be simplified.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram showing one embodiment of the present invention, Figure 2 is a wiring diagram showing an embodiment of the present invention.
The figure is a signal waveform diagram that also serves as a time chart, and FIG. 3 is a characteristic curve diagram based on actual measurements of a capacitor motor. In the figure, 12 is a capacitor motor, 12a, 12
b is the first and second phase windings, 21 and 22 are the first and second reference value generation circuits, 28 and 29 are the first and second comparison circuits, 38 is the time difference detection means, Vs is the reference value,
Va and Vb are winding voltages (terminal voltages).

Claims (1)

[Claims] 1. In a washing machine that has an automatic reversing circuit that periodically reverses the rotation direction by controlling the first and second phase windings of the capacitor motor to alternately act as auxiliary windings, the reference value is A reference value setting circuit that changes depending on a change in voltage, a comparison circuit that simultaneously compares each terminal voltage of the first and second phase windings with the reference value, and a comparison circuit that is based on the output of this comparison circuit. and time difference detection means for detecting a difference in rise time between the terminal voltages of the two windings.