JPH11179089A - Washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a motor to a prescribed rotation speed, to suppress the dispersion of pulse signals when a motor is OFF, to finely set a stream corresponding to the laundry/water ratio and to reduce cloth damages in a washing machine for rotationally driving a stirring blade and a washing and dehydrating tank by the motor. SOLUTION: The stirring blade freely rotatably disposed to the washing and dehydrating tank is driven by the motor 21, the drive of the motor 21 is controlled by controlling switching elements 23a-23f for supplying power to the motor 21 by a control means 25 and the pulse signals are generated for N (natural number) times from pulse generation means 24a-24c while the motor 21 is rotated once. The control means 25 detects the rotation speed of the motor 21 by the cycle of the pulse signals generated by the pulse generation means 24a-24c, controls the switching elements 23a-23f so that the rotation speed of the motor 21 to be the prescribed speed, then stops the drive of the motor 21 and sets the stream in a stirring process based on the pulse signals within a prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a washing machine for rotating a stirring blade and a washing / dewatering tub by a motor.

[0002]

2. Description of the Related Art Conventionally, this type of washing machine has been configured as shown in FIGS. Hereinafter, the configuration will be described.

[0003] As shown in FIG. 10, a water tub 1 includes a washing and dewatering tub 2, and a stirring blade 3 is rotatably provided at the bottom of the washing and dewatering tub 2. The speed reduction mechanism 4 reduces the driving force from the motor 5 via a belt and transmits the driving force to the stirring blade 3 during washing, and transmits the driving force to the washing and dewatering tub 2 during dehydration. The switching between dehydration and washing at this time is performed by driving the drain valve 6. When the drain valve 6 is driven, drainage of the washing water is performed, and the clutch of the speed reduction mechanism 4 is switched to perform the dehydration operation.

The washing tub lid 7 has a folding structure with a hinge at the center, and covers the upper opening of the outer frame 8. The water level detecting means 9 is a connection part (trip point) at a lower part of the water tank 1.
The water level is detected by converting the water pressure of 10 into an electric frequency. The pulse generating means 11 is attached to the motor 5, outputs a pulse signal corresponding to the rotation speed of the motor 5, and inputs the signal to the control device 12.

As shown in FIG. 11, a controller 12 sequentially controls a series of processes such as washing, rinsing, dehydration, etc., and a microcomputer which determines a cloth amount based on a pulse signal input from the pulse generating means 11. Control means 13 and the motor 5 according to a signal from the control means 13,
Load driving means 15 for controlling drain valve 6, water supply valve 14, etc.
And input setting means 17 for setting a driving course and the like, which are constituted by key switches disposed in the operation panel 16.
And display means 1 comprising a display device such as a light emitting diode
8 is provided. Reference numeral 19 denotes an AC power supply, and reference numeral 20 denotes a phase advance capacitor of the motor 5.

The operation of the above configuration will be described. When the laundry is put into the washing / dewatering tub 2 and a key switch for prompting the start of operation is pressed, the control means 13 drives the motor 5 on and off a plurality of times to activate the stirring blades 3. , A pulse signal generated by the pulse generating means 11 is input. Based on the pulse signal, the control means 13 detects the amount of cloth in the washing and dewatering tub 2, sets a water level according to the amount of cloth, and sets a sequence of washing, rinsing, and dehydrating.
To start water supply.

When water gradually accumulates in the water tank 1 and the water level detection means 9 detects that the water level has reached a predetermined level, the control means 13 stops the water supply and drives the motor 5 on and off,
Start the stirring operation. When the motor 5 is off during the stirring operation,
The pulse signal generated by the pulse generation means 11 is input a plurality of times, and based on the pulse signal, if it is detected that the water flow is too strong and the water scatters outside the water tank 1, the ON time of the motor 5 is reduced. By extending the off-time or either, the water flow is weakened to prevent water splattering.

[0008]

In such a conventional configuration, the number of revolutions immediately before the motor 5 is turned off is affected by the power supply voltage, the power supply frequency, the characteristics of the motor itself, and the like, and the pulse generated by the pulse generation means 11 is generated. The variation of the signal is large, and the determination of the amount of laundry to set the water level and the sequence of washing, rinsing, and dehydration and the determination of whether the water flow is too strong are the limits. There was a problem that it was difficult to set a fine water flow corresponding to (bath ratio).

The present invention solves the above-mentioned conventional problems. By controlling the motor to a predetermined number of revolutions, the variation of the pulse signal when the motor is turned off is suppressed, and the fine water flow is set in accordance with the bath ratio. It is intended to reduce

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention controls a switching element for supplying power to a motor by driving a stirring blade rotatably disposed in a washing and dewatering tub by a motor. The driving of the motor is controlled by the means, and a pulse signal is generated N (natural number) times by the pulse generating means during one rotation of the motor or the stirring blade. The control means detects the rotation speed or the rotation cycle of the motor or the stirring blade from the cycle of the pulse signal generated by the pulse generation means, and controls the switching element so that the rotation speed of the motor or the stirring blade becomes a predetermined rotation speed. Thereafter, the driving of the motor is stopped, and the water flow in the stirring process is set based on a pulse signal within a predetermined time.

[0011] Thus, the motor can be controlled to a predetermined rotation speed without being affected by the power supply voltage, the power supply frequency, and the characteristics of the motor itself, so that variations in pulse signals when the motor is off can be suppressed. Therefore, by performing fine water flow setting corresponding to the bath ratio based on this pulse signal, cloth damage can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a stirring blade rotatably disposed in a washing and dewatering tub, a motor for driving the stirring blade, and power supply to the motor. Control means for controlling the switching element to be driven to control the driving of the motor, and pulse generating means for generating a pulse signal N (natural number) times during one rotation of the motor or the stirring blade, wherein the control means comprises: Detecting the rotation speed or rotation period of the motor or the stirring blade from the period of the pulse signal generated by the pulse generation means, and controlling the switching element so that the rotation speed of the motor or the stirring blade becomes a predetermined rotation speed. After that, the driving of the motor is stopped, and the water flow in the stirring process is set based on a pulse signal within a predetermined time. Since the motor can be controlled to a predetermined number of revolutions without being affected by the characteristics of the motor itself, variations in the pulse signal when the motor is turned off can be suppressed, and based on the pulse signal, a fine water flow setting corresponding to the bath ratio is performed. And can reduce cloth damage.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means controls the rotation speed of the motor or the stirring blade to a predetermined rotation speed, and then stops driving the motor. By performing a series of operations of inputting a pulse signal within a predetermined time a plurality of times, the water flow in the stirring process is set, and in consideration of the variation of the pulse signal due to the degree of overlap of different quality cloths, The bath ratio can be detected with high accuracy, an appropriate water flow can be set, and further damage to the cloth can be reduced.

According to a third aspect of the present invention, in the first aspect of the present invention, a water level detecting means for detecting a water level in the washing and dewatering tub is provided, and the control means is configured to detect a water level in the washing and dewatering tub. The predetermined rotation speed of the motor or the stirring blade is changed, and the bath ratio can be detected and the water flow can be set under the predetermined rotation speed at which the most stable pulse signal is generated at each water level. .

According to a fourth aspect of the present invention, in the first aspect of the present invention, the control means sets the water flow in the agitating process based on a ratio between the on time and the off time of the motor. In addition, the water flow suitable for the bath ratio is realized by the ratio of the ON time and the OFF time of the motor, and the fine water flow setting can reduce damage to the cloth.

According to a fifth aspect of the present invention, in the first aspect of the invention, the control means sets the water flow in the stirring process by the rotation speed of the motor or the stirring blade. The strength of the water flow suitable for the ratio can be realized by the number of rotations of the motor, and the damage to the cloth can be reduced by setting the water flow more finely.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those in the conventional example are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 1) As shown in FIGS. 1 and 2, the motor 21 is constituted by a DC brushless motor, and although not shown, a stator having a three-phase winding 22 and a two-pole The first winding 22 comprises a rotor in which permanent magnets are disposed, and the stator comprises a three-phase winding 22.
a, the second winding 22b and the third winding 22c are wound around an iron core provided with slots.

The inverter circuit 23 is constituted by a switching element comprising a parallel circuit of a power transistor (IGBT) and a reverse conducting diode. A series circuit of the first switching element 23a and the second switching element 23b, a series circuit of the third switching element 23c and the fourth switching element 23d, and a fifth switching element 23e and a sixth switching element 23f. The switching element is composed of a series circuit, and the series circuit of the switching elements is connected in parallel.

Here, both ends of the series circuit of the switching elements are input terminals to which a DC power supply is connected, and output terminals are respectively connected to connection points of two switching elements constituting the series circuit of the switching elements. The output terminal is
A U terminal, a V terminal, and a W terminal are connected to three terminals, a U terminal, a V terminal, and a W terminal of the three-phase winding 22, and the combination of on and off of two switching elements that form a series circuit of the switching elements. Are set to three states of positive voltage, zero voltage, and release, respectively.

The switching elements are turned on and off by three pulse generating means 24a, 24b, 2 comprising a Hall IC.
It is controlled by the control means 25 based on the information from 4c. The pulse generating means 24a, 24b, 24c are arranged on the stator at intervals of 120 electrical degrees so as to face the permanent magnets of the rotor.

As shown in FIG. 3, during one rotation of the rotor, three pulse generating means 24a, 24b, 24c
Each pulse is output at the timing shown in the figure. The control means 25 determines the timing of the arrow (3
(When the state of any one of the two pulse generating means has changed), the pulse generating means 24a, 24b, 24
By changing the ON / OFF state of the switching elements 23a to 23f based on the signal c, the U terminal, the V terminal, the W terminal
The terminals are set to three states of positive voltage, zero voltage, and release, and the first winding 22a, the second winding 22b, and the third winding 22 of the stator are provided.
The magnetic field is created by energizing c to rotate the rotor.

The switching elements 23a, 23c,
23e is controlled by pulse width modulation (PWM), for example, by controlling the high / low duty ratio at a repetition frequency of 10 kHz to control the number of revolutions of the rotor. The control means 25 includes three pulse generation means. 24a, 2
Each time the state of any of the signals 4b and 24c changes, the cycle is detected, the rotation speed of the rotor is calculated from the cycle, and the switching elements 23a,
PWM control is performed on 23c and 23e.

The resistor 26 detects the current, and the resistor 2
6, the input current value of the inverter circuit 23 is detected. The commercial power supply 19 is connected to the inverter circuit 23 via a DC power supply exchange device including a diode bridge 27, a choke coil 28, and a smoothing capacitor 29. However, this is only an example, and the configuration of the DC brushless motor 21, the configuration of the inverter circuit 23, and the like are not limited thereto.

FIG. 4 shows that the control means 25 inputs the signals of the pulse generating means 24a, 24b and 24c during the washing and controls the duty ratio of each switching element of the inverter circuit 23 for driving the motor 21. This shows a method for controlling the rotation speed of the stirring blade 3.

First, in step 40, the rotation speed of the motor 21 is set to, for example, 600 r / min, and in step 41, the motor 21 is turned on. Then, in step 42, start control is performed. (Table 1) shows a predetermined energization ratio for each elapsed time from the start of activation. The activation control is based on the energization ratio of (Table 1).
23c and 23e. The values in the table are the values of P when the repetition frequency is, for example, 10 kHz.
It shows the energization ratio (unit%) of the WM signal.

[0027]

[Table 1]

In step 43, in the process of switching from the starting control to the feedback control, an initial value of the duty ratio is set to stabilize the feedback control. In step 44, the rotation period of the motor 21 is detected, the rotation period data is converted into rotation speed data, and the switching elements 23a, 23c, 23
Feedback control is performed on the energizing ratio of e.

Here, the control means 25, as described above,
The number of revolutions of the motor 21 is detected from the cycle of the pulse signal generated by the pulse generation means 24a, 24b, 24c, and the switching elements 23a to 23f are controlled so that the number of revolutions of the motor 21 becomes a predetermined number of revolutions. The drive of the pump 21 is stopped, and the water flow in the stirring process is set based on a pulse signal within a predetermined time.

In the above configuration, FIG. 5, FIG. 6 and FIG.
The operation will be described with reference to FIG. FIG. 5 shows a state of rotation of the motor 21 at the time of washing. The control unit 25 controls the motor 21 to rotate at a predetermined rotation speed (for example, 600 rpm) during time t1.
/ Min) so that the switching elements 23a to 23
f, and then the motor 21 is turned off for a time t2. This is also performed for the reversal, and the stirring operation is performed by repeating the normal reversal.

Next, the operation of setting the water flow based on the pulse signals of the pulse generating means 24a, 24b and 24c will be described with reference to FIG. First, in step 50, the value of the pulse counter is set to 0. The control unit 25 proceeds to step 51, where the pulse generation units 24a, 24b,
24c based on the information from 24c.
The motor 21 is started by changing the ON / OFF state of 23f.

In step 52, the switching elements 23a, 23c, and 23e are PWM-controlled so that the motor 21 has a predetermined number of revolutions, for example, 600 r / min. In step 53, the ON time of the motor 21 has passed the time t3. If not, the flow returns to step 52 again to perform the rotation speed control.
On the other hand, in step 53, the ON time of the motor 21 is set to time t3.
If the time has elapsed, the routine proceeds to step 54, where the switching elements 23a to 23f are turned off to stop driving the motor 21.

In a state where the motor 21 is rotating by inertial rotation, at step 55, the three pulse generating means 24
The signals from a, 24b, and 24c are input, and if the state of any of the signals has changed, the process proceeds to step 56 and the pulse counter is incremented by one. Thereafter, in step 57, if the off time of the motor 21 has not elapsed the time t4, the process returns to step 55, where the pulse generating means 24a,
Wait for the change of 4b, 24c.

In step 55, the pulse generating means 24a,
If there is no change in the state of any of the input signals from 24b and 24c, the elapse of the off time is determined in step 57. If it is determined in step 57 that the off time of the motor 21 has passed the time t4, the process proceeds to step 58 to determine the bath ratio.

The relationship between the pulse counter value and the bath ratio (correlation diagram showing the frequency of the pulse counter value with respect to the bath ratio, a normal distribution table) is as shown in FIG.
The larger the amount of clothing relative to the amount of water in the interior, the greater the frictional resistance between the stirring blade 3 and the clothing, and the shorter the time of inertia rotation after the motor 21 is stopped, the smaller the pulse counter value. It indicates that it will be.
Table 2 shows the bath ratios classified by the pulse counter values based on FIG.

[0036]

[Table 2]

In step 58, the bath ratio division is determined from the pulse counter value in accordance with (Table 2), and the flow shifts to step 59 to set an appropriate water flow corresponding to each bath ratio division.
Thereafter, the stirring operation is performed according to the set water flow. The setting of the water flow corresponding to each bath ratio section will be described later.

In this embodiment, the control means 25 detects the number of revolutions of the motor 21 from the cycle of the pulse signal generated by the pulse generation means 24a, 24b, 24c,
Although the switching elements 23a to 23f are controlled so that the number of rotations of the motor 1 becomes a predetermined number of rotations, the pulse generation means 24
a, 24b, and 24c, the rotation speed or rotation period of the stirring blade 3 is detected from the period of the pulse signal, and the switching elements 23a to 23f are controlled so that the rotation speed of the motor 21 or the stirring blade 3 becomes a predetermined rotation speed. You may.

In this embodiment, the motor 21 is
Although a DC brushless motor has been described as an example, the present invention is not limited to this. In addition, although the driving force of the motor 21 is transmitted to the speed reduction mechanism 4 via a belt and the stirring blade 3 or the washing and dewatering tub 2 is driven to rotate, the method may be directly transmitted to the speed reduction mechanism without using a belt. Alternatively, a method in which the drive of the motor 21 is directly transmitted to the stirring blade 3 or the washing and dewatering tub 2 without a speed reduction mechanism may be employed.

(Embodiment 2) Control means 25 in FIG.
Sets the water flow in the stirring process by controlling the rotation speed of the motor 21 to a predetermined rotation speed, stopping the driving of the motor 21 and performing a series of operations for inputting a pulse signal within a predetermined time period a plurality of times. Like that. Other configurations are the same as those in the first embodiment.

The operation of the above configuration will be described with reference to FIG. First, in step 60, the value of the pulse counter and the value of the water flow counter are set to zero. Then step 5
From 1 to step 57, the motor 21 is controlled to the set number of rotations during the time t3, and the number of pulses generated during the inertial rotation during the time t4 after the motor 21 is turned off is integrated.
The operations from step 51 to step 57 are the same as those in the first embodiment, and a detailed description thereof will be omitted.

If it is determined in step 57 that the off time of the motor 21 has passed the time t4, the process proceeds to step 61, and the water flow counter is incremented by one. In step 62, if the value of the water flow counter is not 8, that is, if the motor 21 has not been inverted eight times, the process returns to step 51, and restarts from the start of the motor 21. On the other hand, if the value of the water flow counter has reached 8 in step 62, the process proceeds to step 63, and the bath ratio classification is determined from the pulse counter value according to (Table 3). Set the water flow and move to the stirring operation.

[0043]

[Table 3]

(Embodiment 3) Control means 25 in FIG.
Is designed to change the predetermined number of revolutions of the motor 21 according to the water level in the washing and dewatering tub 2. Other configurations are the same as those in the first embodiment.

The operation of the above configuration will be described with reference to FIG. First, in step 70, the water level in the washing and dewatering tub 2 is input from the water level detecting means 9. In step 71, a predetermined rotation speed corresponding to the water level in the washing and dewatering tub 2 is set according to the predetermined rotation speed of the motor 21 preset for each water level as shown in (Table 4).

[0046]

[Table 4]

Thereafter, in steps 50 to 57, the motor 21 is controlled to the rotation speed set in step 71 during the time t3, and the pulse generated during the inertial rotation during the time t4 after the motor 21 is turned off. Multiply the numbers.
The operations from step 50 to step 57 are the same as those in the first embodiment, and a detailed description thereof will be omitted.

In step 57, if the off time of the motor 21 has passed the time t4, the process proceeds to step 72,
After determining the bath ratio category from the pulse counter value according to (Table 5), the water flow is set in step 59 and the operation shifts to the stirring operation as in the first embodiment.

[0049]

[Table 5]

(Embodiment 4) Control means 25 in FIG.
Is to set the water flow in the stirring process by the ratio of the ON time and the OFF time of the motor 21. Other configurations are the same as those in the first embodiment.

The operation of the above configuration will be described.
As in the first embodiment, the bath ratio classification is determined. Based on this bath ratio classification, the water flow is set according to (Table 6). Table 6 shows the ratio of the ON time and the OFF time of the motor 21 appropriate for each bath ratio section. The ON time of the motor 21 is time t1 in FIG. 5, and the OFF time is time t2 in FIG.

For example, if the bath ratio is 5.0 to 5.9%, after controlling the motor 21 to a predetermined speed for 1.0 second,
By turning off the motor 21 for 0.6 seconds and repeating the normal rotation and reversal, the laundry in the washing and dewatering tub 2 is rotated by the stirring blades 3 for washing.

[0053]

[Table 6]

(Embodiment 5) Control means 25 in FIG.
Is to set the water flow in the stirring process by the rotation speed of the motor 21. Other configurations are the same as those in the first embodiment.

The operation of the above configuration will be described. Based on the pulse counter value during the inertial rotation of the motor 21,
The bath ratio category is determined in the same manner as in the first embodiment. Based on this bath ratio classification, the water flow is set according to (Table 7). (Table 7) shows the rotation speed of the motor 21 appropriate for each bath ratio category.

For example, if the bath ratio is 6.0 to 6.9%, the rotation speed is 670 r / min, and 670 r / min is set in step 40 in FIG. Shift to control the rotation speed. By repeating the rotation speed control and the motor-off in the normal rotation / inversion, the laundry in the washing / dewatering tub 2 is rotated by the stirring blades 3 and washed.

[0057]

[Table 7]

[0058]

As described above, according to the first aspect of the present invention, the stirring blade rotatably disposed in the washing and dewatering tub, the motor for driving the stirring blade, and the motor Control means for controlling a switching element for supplying power to the motor to control the driving of the motor, and pulse generating means for generating a pulse signal N (natural number) times during one rotation of the motor or the stirring blade, The control unit detects a rotation speed or a rotation period of the motor or the stirring blade from a cycle of a pulse signal generated by the pulse generation unit, and controls the rotation speed of the motor or the stirring blade to a predetermined rotation speed. The switching element is controlled, and then the driving of the motor is stopped, and the water flow in the stirring process is set based on a pulse signal within a predetermined time. Since the motor can be controlled to a predetermined number of revolutions without being affected by the characteristics of the motor itself, variations in the pulse signal when the motor is off can be suppressed, and based on this pulse signal, fine water flow settings corresponding to the bath ratio can be made. Can be performed, and cloth damage can be reduced.

According to the second aspect of the present invention, after the control means controls the rotation speed of the motor or the stirring blade to a predetermined rotation speed, the control means stops driving the motor and outputs a pulse signal within a predetermined time. The water flow in the agitation process is set by performing a series of operations to input the water flow multiple times, so that the variation of the pulse signal due to the degree of overlap of cloths of different qualities is considered, and a more accurate detection of the bath ratio is performed. By doing so, appropriate water flow setting can be performed, and further cloth damage can be reduced.

According to the third aspect of the present invention, there is provided a water level detecting means for detecting a water level in the washing and dewatering tub, and the control means controls the motor or the stirring blade according to the water level in the washing and dewatering tub. Since the predetermined rotation speed is changed, the bath ratio can be detected and the water flow can be set under the predetermined rotation speed at which the most stable pulse signal is generated at each water level.

According to the fourth aspect of the present invention, the control means determines the ratio between the on-time and the off-time of the motor.
Since the water flow in the stirring process is set, a water flow suitable for the bath ratio can be realized by the ratio of the on-time to the off-time of the motor, and fine water flow settings can reduce cloth damage.

According to the fifth aspect of the present invention, the control means sets the water flow in the stirring process by the rotation speed of the motor or the stirring blade, so that the strength of the water flow suitable for the bath ratio is set. Can be realized by the number of rotations of the motor, and the damage to the cloth can be reduced by setting the water flow to be further subdivided.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a washing machine according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the washing machine.

FIG. 3 is an operation timing chart at the time of inverter control of the washing machine.

FIG. 4 is an operation flowchart of a main part of the washing machine at the time of controlling the number of rotations of the motor.

FIG. 5 is an operation timing chart at the time of controlling the number of rotations of the motor of the washing machine.

FIG. 6 is an operation flowchart of a main part of the washing machine.

FIG. 7 is a correlation diagram between the bath ratio of the washing machine and the number of pulse counters.

FIG. 8 is an operation flowchart of a main part of a second embodiment of the present invention.

FIG. 9 is an operation flowchart of a main part of a third embodiment of the present invention.

FIG. 10 is a longitudinal sectional view of a conventional washing machine.

FIG. 11 is a block circuit diagram of the washing machine.

[Explanation of symbols]

 2 Washing and dewatering tub 3 Stirrer blade 21 Motor 23a to 23f Switching element 24a to 24c Pulse generating means 25 Control means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Sadayuki Tamae 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] A control for controlling a driving of the motor by controlling a stirring blade rotatably disposed in a washing and dewatering tank, a motor for driving the stirring blade, and a switching element for supplying electric power to the motor. Means for generating a pulse signal N (natural number) times during one rotation of the motor or the stirring blade, the control means controlling the motor based on a cycle of the pulse signal generated by the pulse generation means. Or, by detecting the rotation speed or rotation cycle of the stirring blade, the switching element is controlled such that the rotation speed of the motor or the stirring blade becomes a predetermined rotation speed, and thereafter, the drive of the motor is stopped, and a predetermined time period is elapsed. A washing machine that sets a water flow in a stirring process based on a pulse signal in the washing machine. 2. The control means controls the number of rotations of a motor or a stirring blade to a predetermined number of rotations, stops driving the motor, and performs a series of operations of inputting a pulse signal within a predetermined time a plurality of times. The washing machine according to claim 1, wherein the water flow in the agitation process is set by the following. 3. The washing and dewatering tub further comprises a water level detecting means for detecting a water level in the washing and dewatering tub, and the control means changes a predetermined number of rotations of the motor or the stirring blade according to the water level in the washing and dewatering tub. The washing machine as described. 4. The washing machine according to claim 1, wherein the control means sets the water flow in the agitating process based on a ratio between an on time and an off time of the motor. 5. The washing machine according to claim 1, wherein the control means sets the water flow in the stirring process by the rotation speed of the motor or the stirring blade.