JPS6037115Y2 - Automatic washing machine water level detection device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a water level detection device for an automatic washing machine that operates according to a preset program.

In an automatic washing machine, detecting the amount of water in the water supply tank, that is, the water level, is an essential element in executing programs such as washing, rinsing, and spin-drying.

In conventional automatic washing machines that have a dual structure of a washing tank and a dewatering tank, a pressure switch using air is installed in the washing tank to detect the water level.

This is because since the washing tank is fixed, it is possible to easily obtain pressure according to the water level.

In recent years, the washing tank of automatic washing machines has been changed from the conventional double structure to a splash-proof tank that rotates at high speed in order to save water, eliminate the need for a drain valve, and prevent clogging even when using a powder bed. , a single tank that drains water from the top of the washing tank using centrifugal force is attracting attention.

However, since the washing tank itself rotates as described above, it has become impossible to detect the water level using a pressure switch using air, which is the conventional method of detecting the water level.

One method of water level detection that has been proposed is to use the electrical conductivity of water, but as is well known, the electrical conductivity of tap water varies from region to region and is extremely unstable.

In addition, in the above method, a water outlet hole is provided in the upper side wall of a single tank, that is, a washing and dewatering tank, and the overflow of the washing liquid from the hole is detected, so the water level cannot be set in multiple stages. However, there are drawbacks such as the washing liquid flowing out from the water outlet during washing.

Next, a method of detecting the water level in the washing and dehydrating tank by detecting the weight of the tank was devised.

Figure 1 shows a specific example of the water level detection method based on the weight of the washing and dehydrating tank.

In FIG. 1, reference numeral 1 denotes an outer box, which has no dehydrating holes and is provided with a taper-shaped washing and dehydrating tank 2 that widens somewhat toward the upper opening.

The upper opening of the washing and dehydrating tank 2 is provided with a ring-shaped balance ring 3 located with a slight gap from the wall surface, and a rotary blade 4 rotatably provided in the center of the washing and dehydrating tank 2. ing.

Reference numeral 5 denotes a case that supports the washing and dewatering tank 2 and the rotary blade 4 via a shaft 6, and the bearing case 5 is attached to a support plate 7. A lower spherical catch 8 is provided.

The upper inner wall of the outer box 1 is provided with an upper spherical seat 9 corresponding to the lower spherical seat 8 of the support plate 7, and between these spherical seats 8 and 9 are spherical bodies 10. The washing and dewatering tank 2 is elastically supported by a hanging rod 12 and a vibration-proofing spring 13 via a suspension rod 11 .

This hanging rod 12 is positioned diagonally so that the lower part faces the center.

The upper end of the hanging rod 12 protrudes above the upper spherical body 11, and a weight detecting section 14 is attached to the tip thereof.

Reference numeral 15 has one end fixed to the outer box 1, a water receiver located between the washing and dehydration tank 2 and the support plate 7 at the center of the waist, and a sealing material 16 and a vibration comb at the contact part with the shaft 6. 17.

Reference numeral 18 denotes a water supply electromagnetic valve that determines the water level using the control circuit 19 based on the force from the weight detection section 14, and turns off the water supply operation depending on the determined state.

Further, a motor 20 is attached to the lower surface of the support plate 7, and the motor 20 is connected to the shaft 6 via a timing belt 21.
It is designed to transmit rotational force from the

Note that 22 is a drainage pipe, and the water receiver is connected to a hole provided at the bottom of the tank 15.

FIG. 2 shows the detailed structure of the weight detection section 14.

In FIG. 2, 23 is a detector case, which is hollow and made of non-magnetic material such as plastic, and has an upper spherical body 11.
is fixed at the top of the.

The hanging rod 12 is inserted into the detector case 23, and the hanging rod 1
Spring receiver 24 fixed to the upper tip of 2 with a fixing pin 25
is fixed, and the spring receiver 24 and the detector case 2
A spring 26 having a relatively larger spring constant than the vibration isolating spring 13 is provided between the vibration isolating spring 13 and the bottom of the vibration isolating spring 13 .

27 is a movable disk made of magnetic material such as iron, and the spring 2
8 always receives a downward force from the top, and also slides on the inner wall of the detector case 23.

A board 29 is attached to the detector case 23 near the movable disk 27, and two magnetoresistive elements 30 and a ferrite magnet 31 are fixed to the board 29.

Therefore, a magnetic circuit is formed by the movable disk 27 and the ferrite magnet 31, and the magnetic circuit resistance element 30 is located within the magnetic circuit.

In the automatic washing machine of the weight detection water level detection system configured as described above, a conventional control circuit 19 is shown in FIG.

In the figure, 32 is a DC power supply, and DC power is supplied to the series circuit of the magnetoresistive elements 30 in the weight detection section 14.

33 and 34 are resistors respectively connected to both ends of the variable resistor 35 for water level setting, and the DC power supply 32 is applied to the series circuit of the resistors 33 and 34 to provide a water level setting range.

The inverting input (-) terminal of the voltage comparator 36 has a water level setting potential which is the variable output of the water level setting variable resistor 35, and the non-inverting input (+) terminal has the potential at the midpoint of the series circuit of the magnetoresistive elements 30. Each is entered.

An output relay 37 is connected to the output end of the voltage comparator 36, and the contact of the output relay 37 causes the water supply solenoid valve 18 to be activated.
It is designed to turn the operation on and off.

Next, the operation of a conventional automatic washing machine using a weight detection water level detection method will be explained.

The magnetoresistive element 30 is an element whose resistance value changes depending on the strength of the magnetic field that affects it, and temperature characteristics can be corrected by connecting the magnetoresistive elements 3 in a row.

As shown in FIG. 2, a magnetic circuit is constructed by a ferrite magnet 31 and a movable disc 27 made of a magnetic material, and with a magnetic resistance element 30 inserted into the magnetic circuit, the movable circle 27 is parallel to the ferrite magnet 31. When the magnetoresistive element 30 is moved up and down, a change occurs in the magnetic circuit, and the resistance value of the magnetoresistive element 30 changes accordingly.

Therefore, when the movable disk 27 moves downward, the potential at the midpoint of the series circuit of the magnetoresistive elements 30 shown in FIG. 3 is configured to decrease in proportion to the distance moved.

At the start of the water supply process, if there is no water in the washing and dehydration tank 2 or the water level has not reached the specified level, the weight of the washing and dehydration tank 2 is small, so the weight of the washing and dehydration tank 2 causes the water to drop to the top of the hanging rod 12. Since the spring 26 in the attached weight detection unit 14 is not sufficiently compressed, the movable disk 27 is located parallel to the ferrite magnet 31 and relatively upward.

Therefore, the output of the magnetoresistive element 30, that is,
The voltage applied to the non-inverting input (+) terminal of the voltage comparator 36 is a high value, and the voltage at the inverting input (-) terminal, to which a voltage corresponding to the set water level is applied, is lower, so the voltage The output of comparator 36 becomes low level, and output relay 3
Drive 7.

Since the water supply solenoid valve 18 is connected to the contact point of the output relay 37, the water supply solenoid valve 18 is turned on and supplies water to the washing and dewatering tank 2.

After water supply starts, water gradually accumulates in the washing and dehydrating tank 2, and the spring 26 in the weight detection unit 14 is gradually compressed due to its weight, and the movable disk 27 is moved downward by the upper spring 28. It is pushed and moves in that direction.

Therefore, the voltage at the non-inverting input (+) terminal of the voltage comparator 36 also bottoms out depending on the weight, that is, the amount of water supplied.

The non-inverting input (+) terminal is connected to the water level setting variable resistor 35.
When the voltage of the inverting input (-) terminal set in advance is reached, that is, when the potential relationship between both inputs of the voltage comparator 36 is reversed, the output is inverted and becomes bi-level.
Stops driving the output relay 37.

As a result, the water supply solenoid valve 18 closes and the water supply process ends.

The conventional automatic washing machine with weight detection water level detection method is configured as described above, so the instability caused by variations in the quality of the water used and the drawbacks of the water level detection method using narrow groove electric rate can be improved. Ta.

However, in this method, the water level is detected by the weight of the washing/dehydrating tank 2, so when the water level of the washing/dehydrating tank 2 approaches the set water level, the items to be washed inside the washing/dehydrating tank 2 are immersed in water. If weight is artificially added to the washing and dehydration tank 2 for purposes such as washing, the weight will be superimposed on the washing and dehydration tank 2,
There is a drawback that the water supply process ends as if the set water level has been reached.

This idea was made to eliminate the above-mentioned drawbacks of the conventional method. By adding a device that removes weight changes other than the water supply to the washing/dehydrating tank, it is possible to accurately detect the water level according to the set water level. The purpose of the present invention is to provide a water level detection device for an automatic washing machine.

Hereinafter, an embodiment of the water level detection device for an automatic washing machine of this invention will be described with reference to the drawings.

FIG. 4 is a circuit diagram showing one embodiment of the present invention, and 32 is a DC power supply, which is connected to a series circuit of magnetoresistive elements 30 as in the conventional case.

The voltage at the midpoint of the series circuit of the magnetoresistive elements 30 is the voltage of the resistor 3
8. A voltage applied to both ends of the resistor 39 connected in series, and divided by the resistance ratio of the resistor 38 and the resistor 39, is input to the inverting input (-) terminal of the voltage comparator 42.

A control relay 43 is connected to the output of the voltage comparator 42, and one end of a contact 44 of the control relay 43 is connected to an intermediate point of the series circuit of the magnetoresistive elements 30.

The other end of the contact 44 of the control -L/-43 is connected to the non-inverting input (+) terminal of the voltage comparator 42 via a charging/discharging circuit consisting of a resistor 40 and a capacitor 41.
Connected to the non-inverting force (+) terminal of the

On the other hand, as in the conventional case, a voltage corresponding to the set water level obtained by the resistor 33, the water level setting variable resistor 35, and the resistor 34 is applied to the inverting input (-) terminal of the voltage comparator 36, and the output terminal of the voltage comparator 36 is connected to the water supply solenoid valve. An output relay for opening and closing 18 is connected.

As before, the voltage at the midpoint of the series circuit of the magnetoresistive elements 30 is an output corresponding to the weight of the washing and dehydrating tank 2.

This voltage is divided by the resistor 38 and the resistor 39 and applied to the inverting input (-) terminal of the voltage comparator 42, and at the same time,
The above output voltage is applied to the charging/discharging circuit of the resistor 40 and the capacitor 41 when the control relay contact 44 is closed.

The output of this charging/discharging circuit is the non-inverting input (
+) terminal, and the charging/discharging circuit is set to a time constant that follows the voltage change of the magnetoresistive element 30 corresponding to the change in weight due to water supply.

Therefore, during normal water supply, the voltage comparator 4
The voltage at the inverting input (-) terminal is lower than the input voltage at the non-inverting input (+) terminal of No. 2 by the amount divided by the resistor 38 and the resistor 39, and its output becomes low level and the control relay 4
Continue to drive 3.

On the other hand, if there is a weight change other than water supply for some reason, such as when a person applies gravity to the washing and dehydration tank, the weight change is considered to be significantly larger than that when water is supplied.

If such a large change is applied to the washing and dehydrating tank, the output voltage of the magnetoresistive element 30 will inevitably decrease rapidly.

Following this, the voltage at the inverting input (-) terminal of the voltage comparator 42 divided by the resistor 38 and the resistor 39 also decreases.

However, the voltage applied to the non-inverting input (+) terminal is maintained at approximately the same potential due to the time constant of the resistor 40 and capacitor 41.

Therefore, the potential relationship between both input terminals of voltage comparator 42 is reversed, its output terminal becomes bi-level, and control relay 43 is turned off.

As a result, the control relay contact 44 becomes open, but
The voltage at the non-inverting input (+) terminal of the voltage comparator 42 is not discharged due to the charge stored in the capacitor 41 and maintains its voltage value.

This is because the input side to which the resistor 40 is connected is in an open state due to the control relay contact 44, and the input impedance of the voltage comparator 42 and the voltage comparator 36 is very large.

In this way, even if a sudden weight is added to the washing and dehydrating tank, the voltage comparator 36 compares the voltage with the set water level.
Since the non-inverting input (+) terminal voltage of the pump is also maintained at the previous voltage value, the water supply operation continues without inverting its output.

When the weight added to the washing and dehydrating tank 2 is released, the voltage divided by the resistor 38 and the resistor 39, that is,
The voltage at the inverting input (-) terminal of the voltage comparator 42 becomes high and returns to the normal state.

In this state, as described above, the output of the voltage comparator 42 becomes low level due to the relationship between both input potentials, and the control relay 4
3, the control relay contact 44 closes, and the output voltage of the magnetoresistive element 30 increases again between the resistor 40 and the capacitor 41.
is applied to the charging/discharging circuit.

As in the conventional circuit, the magnetoresistive element is When the output voltage of 30 becomes lower than the voltage of the non-inverting input (+) terminal applied through the charge/discharge circuit, that is, when it reaches the set water level, the output is inverted and becomes bi-level, and the output Driving of the relay 37 is stopped and the water supply process is completed.

Furthermore, in the above embodiment, a relay contact is used to open and close the voltage output according to the weight obtained from the charging/discharging circuit consisting of the resistor 40 and the capacitor 41 and the magnetoresistive element 30.
A similar effect can be achieved even with a semiconductor switch such as an analog switch.

It goes without saying that the same effect can be obtained even if the above embodiment is realized by software using a stored program type control device such as a microcomputer which is currently being used.

As described above, according to the water level detection device for an automatic washing machine of this invention, in a device that indirectly detects the water level by the weight change due to water in the washing/dehydrating tank, the weight is artificially added to the washing/dehydrating tank. Even in such a case, by utilizing the fact that the disturbance weight is a sudden change and adding a device to remove it, it is possible to achieve high precision and reduce malfunctions.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the configuration of an automatic washing machine using the weight detection water level detection method, Fig. 2 is a sectional view showing the structure of the weight detection section used in the weight detection water level detection method of Fig. 1, and Fig. 3 is FIG. 4 is a control circuit diagram of a water supply solenoid valve in a conventional water level detection device for an automatic washing machine. FIG. 4 is a circuit diagram showing an embodiment of the water level detection device for an automatic washing machine according to the present invention. 14... Weight detection unit, 27... Movable disc, 30... Magnetoresistive element, 31...
Ferrite magnet, 32...DC power supply, 33.3
4.38. 39...Resistance, 35...
Water level setting variable resistor, 36.42... Voltage comparator 37... Output relay, 40... Charging resistor, 41... Charging capacitor, 43.・・・
...Control relay, 44...Control relay contact. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] An automatic washing machine that sequentially executes washing processes such as water supply, washing, and dehydration according to a preset program has a weight detection section that detects the weight of the washing tank containing ice inside, and an output of the weight detection section that is connected via a contact point. a charging/discharging circuit to which the water is applied, and a first comparison driving means that compares the voltage of the charging/discharging circuit with the voltage corresponding to the set water level and stops the water supply to the washing tank when the two reach a predetermined relationship; The present invention is characterized by comprising second comparison drive means that compares the voltage of the charging/discharging circuit with the voltage related to the output of the weight detection section and opens the contact when the voltage related to the output of the weight detection section suddenly changes. Water level detection device for automatic washing machines.