JP3914514B2 - Washing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention detects vibration of the outer tub of the washing machine, collision between the casing and the outer tub (abnormal vibration), and sounds generated by various actuators constituting the washing machine, and based on the detected information. More particularly, the present invention relates to a washing machine equipped with a vibration sensor using a piezoelectric element as a detection means.
[0002]
[Prior art]
The vertical fully automatic washing machine has a washing tub (outer tub) containing a washing tub and dewatering tub elastically supported in the washing machine casing, and a washing machine provided rotatably in the outer tub by a motor attached to the outer tub. It has a structure that rotates the tank and dewatering tank (inner tank), and if an imbalance occurs due to the cloth pieces in the washing tank and dewatering tank (hereinafter referred to as the inner tank), the outer tank is moved along with the rotation of the motor. Swing around. When the outer sway of the outer tub increases, vibration and noise given to the external environment become a problem. Therefore, monitoring these and taking appropriate measures is important in designing the washing machine.
[0003]
Various methods, such as a piezoelectric type, a distortion type, a resonance type, and a photoelectric type, have been proposed as a vibration detection unit and a collision (abnormal vibration) detection unit between a casing and an outer tub in a washing machine.
[0004]
For example, the device described in Patent Document 1 is composed of a unimorph piezoelectric element, a weight having a protrusion, a piezoelectric element and a spring for restraining the weight, and a case for housing them. By making contact with the surface of the metal diaphragm, a force corresponding to the acceleration generated in the weight is applied to the metal diaphragm, and vibration is detected.
[0005]
In addition, what is described in Patent Document 2 is a vibration sensor characterized in that a coil spring is provided at the center of the lower surface of the diaphragm in a water level detection device / vibration detection device composed of a coil, a core, a capacitor, and a diaphragm. It is arranged at the upper part of the outer frame of the washing machine and detects vibration.
[0006]
Furthermore, the drum-type washing machine described in Patent Document 3 has a reflecting plate in which at least two types of portions having greatly different reflectances are alternately arranged in stripes, and a light emitting element and a light receiving device at a position facing the reflecting plate. An optical detector composed of elements is arranged, and one of them is moved in synchronization with the vibration of the rotating drum, and the other is kept stationary to detect the vibration.
[0007]
In a home washing machine, a fully automatic washing machine that performs all washing procedures automatically is the mainstream. When the user presses the start button, the washing machine determines the amount of laundry that has been put in and supplies the necessary water. Then, washing and dehydration are performed under standard conditions prepared in advance in the washing machine. This is performed while controlling the actuator necessary for each washing process by a control device constituted by a microcomputer or the like.
[0008]
As more functions are added to the washing machine, the number of actuators installed in the washing machine has increased, and a complex washing process is performed by combining these functions. For this reason, the chance of failure continues to increase. In addition, a single failure phenomenon involves a plurality of actuators, and the same phenomenon is often exhibited regardless of which actuator fails. For this reason, there are many cases where a dealer or a repair service person is at a loss about which faulty part should be replaced in a failure report from a user.
[0009]
As a prior art for solving this problem, many manufacturers use a display on an operation panel and display an error code here to identify a defective product to some extent. However, the failure part is specified by an electrical detection means. That is, electrical failures of various actuators can be detected, but failures such as mechanical failures such as poor fitting and noise on the sliding surface due to wear cannot be detected.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-14445
[Patent Document 2]
JP 2002-273096 A
[Patent Document 3]
Japanese Patent Laid-Open No. 10-2335070
[0011]
[Problems to be solved by the invention]
A vibration detection apparatus using a piezoelectric element as described in Patent Document 1 has a simple configuration and is relatively inexpensive as a sensor for detecting acceleration. However, due to the nature of detecting the acceleration by bending the piezoelectric element itself having a small mass, a sufficient output cannot be obtained in a low frequency range where the force due to the acceleration is small. For this reason, it is necessary to devise a method of applying a force F synchronized with the vibration to the piezoelectric element using some method. In the example described in Patent Document 1, a force of F = ma is directly given to the piezoelectric element by acceleration a by adding a weight having a mass m larger than the mass of the piezoelectric element itself. However, a drawback of this method is that a concentrated load due to gravity is always applied to the piezoelectric element from the weight, and therefore there is a risk of damaging the piezoelectric ceramic that is the piezoelectric element.
[0012]
In the example described in Patent Document 2, although the durability is satisfactory, since the sensor is disposed on the upper part of the outer frame of the washing machine, the vibration of the outer tub itself is not detected but is swayed by the outer tub. The vibration of the outer frame will be detected. For this reason, there exists a problem that the output obtained changes with the installation state of a washing machine.
[0013]
In addition, in the example described in Patent Document 3, since it is composed of a light detection unit including a light emitting unit and a light receiving unit and a reflection plate that reflects light, the cost is slightly higher than other methods. Become. In addition, since the reflector and the light detection unit cannot be sealed, contamination of the foreign material, contamination of the reflection plate and the light detection unit cause malfunctions, and it is fatal that vibration cannot be detected at all when the optical axis is shifted. Have a serious problem.
[0014]
A first object of the present invention is to provide a vibration sensor that detects vibration in a cheaper and more reliable manner, and to provide a washing machine with low vibration and low noise by mounting the vibration sensor on the washing machine. With the goal. Another object of the present invention is to reliably detect primary resonance and secondary resonance large vibration during dehydration, which cannot be performed by a conventional mechanical touch switch, and to improve reliability.
[0015]
The second object of the present invention is to collect sound (audible sound) generated by a mechanical failure by sound collecting means comprising a piezoelectric element, and analyze this to analyze the mechanical of each actuator constituting the washing machine. The purpose is to detect faults. In addition, in the case of a failure involving multiple actuators, it is possible to identify the failed actuator by collecting multiple sounds from each actuator collected by this sound collection means using the drive signal of each actuator as a trigger and analyzing it. Objective. In addition, by combining an electrical failure detection means and a mechanical failure detection means using the sound collected by the sound collection means, the accuracy of failure actuator detection is improved, and a washing machine capable of responding to a failure quickly and appropriately is provided. For the purpose.
[0016]
Also, a washing machine with low vibration and low noise as in the first object is detected by detecting an abnormal operation of the washing machine with the sound collecting means, for example, a collision sound between the tub and the outer frame due to a cloth piece when dewatering, and a vibration sound of the tub. The purpose is to provide.
[0017]
[Means for Solving the Problems]
The washing machine of the present invention includes an outer tub that is a water receiving tub that is swingably suspended in a housing, an inner tub that is rotatable about a rotation axis provided in a vertical direction of the outer tub, In a washing machine equipped with a motor for rotating a tub, a case in which a piezoelectric diaphragm comprising a piezoelectric element and a metal plate to which the piezoelectric element is bonded, and an outer periphery of the piezoelectric diaphragm are supported and incorporated in a water seal A vibration sensor comprising: an upper or lower portion of the outer tub so that the polarization direction of the piezoelectric element is parallel to the rotation axis of the inner tub, The case is constituted by a cylindrical case having an open end having an acoustic resonance space for resonating audible vibration sound of the metal plate, and includes a vibration sensor circuit to which the piezoelectric element is connected, and the vibration sensor circuit has a different resistance value. A resistor with a resistance value that has two types of resistors and has a resistance value smaller than that when detecting vibration acceleration when sounding when performing sound generation due to the normal piezoelectric effect and when detecting vibration acceleration due to the reverse piezoelectric effect. To switch the connection of the two resistors so that a capacitor is connected in parallel to the piezoelectric element It is a thing.
[0018]
A vibration sensor comprising a piezoelectric diaphragm comprising such a piezoelectric element of the present invention and a metal plate to which the piezoelectric element is bonded, and a case supporting the outer periphery of the piezoelectric diaphragm and incorporating the piezoelectric diaphragm is a piezoelectric sensor. It has a structure that doubles as a buzzer and an audible sound collector.
[0019]
According to the present invention, since this vibration sensor is installed in the upper or lower part of the outer tub so that the polarization direction of the piezoelectric element is parallel to the rotation axis of the inner tub, by connecting this vibration sensor to the sensor circuit, It is possible to detect the vibration in the vertical direction of the outer tub, generate an audible notification sound, and realize various audible abnormal sounds. Moreover, a washing machine in which these detection signals are reflected in the operation control of the washing machine can be obtained.
[0020]
When the rotation speed of the inner tub of the washing machine is low, the audible sound output of this vibration sensor detects a collision with the casing of the outer tub that is a water receiving tub, and conversely, the rotation speed of the inner tub is below a predetermined value. If it is high, the vibration of the outer tub due to the cloth imbalance is detected by the vibration output of the vibration sensor in the vertical direction, and noise is estimated, and the maximum rotation speed and dewatering time of this inner tub are determined according to the noise. Control the dehydration process of this washing machine.
[0021]
Thereby, noise during dehydration can be suppressed. Furthermore, since vibration detection and collision detection can be performed, it is an alternative to a collision detection lever, and the cost of the product can be reduced.
[0022]
During dehydration, the vibration of the outer tub is constantly monitored by the vibration detection output of the vibration sensor, and the rotation speed is controlled according to the magnitude of the vibration. Thereby, the washing machine can reduce vibration and noise without stopping the operation.
[0023]
Similarly, by constantly monitoring changes in vibration amplitude, it is possible to prevent abnormal vibration and noise from occurring due to a sudden increase in amplitude.
[0024]
In addition, the audible sound generated by various actuators and mechanism parts during washing and dehydration processes is monitored by the audible sound detection output of this vibration sensor, and mechanical failure is detected and the location of the failure is identified, thereby ensuring the reliability of the washing machine. Can respond quickly to failures.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Examples of embodiments of the present invention will be described below.
[0032]
An example of an embodiment of the washing machine of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of a washing machine excluding a front outer frame (housing) according to this example. FIG. 2 is a block diagram of the control unit of the washing machine. FIG. 3 is a cross-sectional view of the vibration sensor of this example. FIG. 4 is a cross-sectional view of another vibration sensor of this example. FIG. 5 shows a vibration sensor circuit according to this example.
[0033]
First, the outline about the washing machine which mounted the vibration sensor of this example is demonstrated using FIG. In FIG. 1, reference numeral 1 denotes an outer frame (housing) of the washing machine. On the upper part of the outer frame (housing) 1, the outer tub 4 is suspended swingably by a suspension rod 10 having a damper 11. A lower part of the outer tank (water tank) 4 includes a driving unit 8 including a DC motor, a gear, a clutch, and the like, and a flange 9 that connects the driving unit 8 to the outer tank 4, and an output shaft of the driving unit 8 has an inner tank ( The rotating shaft of the washing tub / dehydration tub 5 and the stirring blade 7 is fastened.
[0034]
The outer tank (water tank) 4 has a hole in a part of the lower part, and a drain hose 13 is connected to the hole via a drain valve 12. Further, a top cover 2 is installed on the upper part of the outer frame (housing) 1, and a water supply port and a water supply valve 14 for supplying tap water to the laundry input door 3 and the outer tub 4, a swing switch 17, and the like. is set up.
[0035]
At the time of washing, first, tap water is supplied from the water supply valve 14, and water accumulates in the outer tub (water tank) 4. At this time, the drain valve 12 is closed. After a predetermined amount of water is supplied, the water supply valve 14 is closed, the stirring blade 7 is rotated by the drive unit 8, and the clothes in the inner tub 5 are stirred to remove dirt. At this time, a water flow is generated in the outer tub (water tank) 4 by the rotation of the stirring blade 7 and the clothes are only stirred in the water, so that a vibration that poses a special problem does not occur.
[0036]
On the other hand, at the time of dehydration, first, the drain valve 12 is opened, and the water in the outer tank (water tank) 4 is discharged. In order to prevent foaming due to residual detergent during dehydration and imbalance caused by clothing, the inner tub 5 is rotated when some water remains. A large number of holes are provided in the inner tank 5 and on the surface of the stirring blade 7, and moisture contained in clothes in the rotating inner tank 5 can be removed by centrifugal force.
[0037]
At this time, since the inner tub 5 (having clothes containing moisture inside) having a large mass (rotational moment) rotates at a high speed, an excessive imbalance generated by the clothes inside the inner tub 5 is large. Causes vibration and noise.
[0038]
The shake switch 17 is configured by a micro switch or the like, and a lever 17 a that interlocks with the micro switch extends from the top cover 2 to the vicinity of the outer tub 4. The microswitch is normally open, and when the outer tub 4 is swung so as to come into contact with the outer frame, the microswitch is closed by hitting this lever.
[0039]
The washing machine control unit shown in FIG. 2 has a control circuit A51 for controlling a drive unit 8 including a DC motor, a gear, a clutch, and the like, a water supply valve 14 and a drain valve, with a main control unit (MCU) 50 composed of a microcomputer as the center. 12 includes a control circuit 52, a control circuit 53, and the like. The rotation of the water supply valve 14, the drain valve 12, the stirring blade 7 during washing, and the rotation of the inner tub 5 during dehydration are controlled by a program stored in the MCU 50 in advance.
[0040]
The vibration sensor 16a is connected to the vibration sensor circuit 55, the output terminal A56 of the vibration sensor circuit 55 is connected to the AD input terminal A57 of the MCU 50, and the output terminal B58 is also connected to the other AD input terminal B59. The output terminal 60 of the MCU 50 is connected to the input terminal 61 of the vibration sensor circuit 55, and the vibration sensor 16a connected to the vibration sensor circuit 55 is sounded as a piezoelectric buzzer with an output rectangular wave signal. The shake switch 17 is connected to one input terminal of the MCU 50 and notifies the MCU that the outer tub 4 has come into contact with the lever 17a.
[0041]
Next, the configuration of the vibration sensor 16a will be described with reference to FIGS. 3A and 3B. 3A and 3B, reference numeral 21 denotes a piezoelectric element (piezoelectric ceramic). A metal such as silver is vapor-deposited on one end face to form a metal thin film 21a, and the other end face is bonded to a metal disc 22. The metal disk 22 to which the piezoelectric element (piezoelectric ceramic) 21 is bonded is particularly referred to as a piezoelectric diaphragm Bz1. The piezoelectric element (piezoelectric ceramic) 21 is polarized in the thickness direction. The piezoelectric element (piezoelectric ceramic) 21 has a property of contracting when a voltage in the same direction as the polarization direction is applied and expanding when a reverse voltage is applied. This is called the positive piezoelectric effect.
[0042]
Conversely, when a force F is applied in the polarization direction, a voltage corresponding to the strain due to the force F is output. This is called the inverse piezoelectric effect, and the vibration sensor 16a utilizes this property. The outer periphery of the metal disk 22 is supported on the piezoelectric diaphragm case 23 by silicon rubber or the like (peripheral support). As a general support method, there is also a method of supporting a peripheral portion of a piezoelectric element (piezoelectric ceramic) (node support).
[0043]
In the peripheral support, the vibration around the piezoelectric diaphragm Bz1 can be controlled to lower the resonance frequency of the piezoelectric diaphragm Bz1. The piezoelectric diaphragm case 23 is provided with a suitable resonance space 26 and a hole 27 above the resonance space so as to resonate audible frequency sound generated by the vibration of the piezoelectric diaphragm Bz1.
[0044]
This is because when the piezoelectric diaphragm Bz1 is used as a piezoelectric buzzer, it is not possible to obtain a very loud sound simply by supporting the nodal circle and the periphery, so that a large sound pressure can be obtained on the resonance space 26 on the piezoelectric diaphragm. This is because it is necessary to match the acoustic impedance with the air in the hole 27 above the resonance space.
[0045]
The impedance matching is performed by appropriately designing the above-described resonance space 26 and the hole 27 above the resonance space 26 to constitute an optimum resonator. At this time, the resonance frequency of the piezoelectric diaphragm Bz1 is designed to be an audible frequency (for example, about 2 [kHz]), and the resonator is also designed according to this resonance frequency. The resonance frequency of the piezoelectric diaphragm Bz1 can be adjusted by adjusting the thickness, material, shape, etc. of the metal plate of the piezoelectric diaphragm Bz1.
[0046]
In other words, having a function as a piezoelectric buzzer (sounder) can also be said to have a role as a sound collector (microphone). Monitoring the “abnormal noise”, which is a major factor in customer complaints with a sound collector, and identifying the cause of the noise lead to improved customer satisfaction.
[0047]
In FIG. 3, reference numeral 25 denotes a lead wire of the piezoelectric diaphragm Bz1, which is directly soldered to the metal thin film 21a and the metal disk 22 that are ohmically connected to the piezoelectric element 21. The lead wire 25 is taken out to the outside so as not to be broken or obstructed by the vibration of the vibration sensor 16 a and connected to the vibration sensor circuit 55. At this time, after performing a water sealing process such as packing so that water does not enter from the lead wire takeout part or the like, the whole is sealed with the sensor case cover 24.
[0048]
Here, the sensor case cover 24 is not necessary if the piezoelectric element 21 of the vibration sensor 16a can be waterproofed with silicon or the like. When the sensor case cover 24 is not provided, the function as the above-described sound collector is increased.
[0049]
A vibration sensor 16a without a sensor case cover is shown in FIG. In FIG. 4, parts corresponding to those in FIG. 21b is a film (waterproof coat) of a waterproof material. A waterproof coating is applied to cover the entire piezoelectric element (piezoelectric ceramic) 21. As is well known, piezoelectric ceramics easily contain moisture. When the piezoelectric ceramic contains moisture, the reverse piezoelectric effect is lowered and the reverse piezoelectric voltage due to vibration is reduced. For this reason, when installing in a high-humidity washing machine, a waterproof coating on the piezoelectric ceramic is required.
[0050]
Next, the vibration sensor circuit 55 to which the vibration sensor 16a is connected will be described with reference to FIG. A switching circuit for switching whether the vibration sensor 16a functions as a piezoelectric buzzer or a vibration sensor 16a and an audible sound collector, a drive circuit for the piezoelectric buzzer, and an amplification for amplifying the vibration detection (reverse piezoelectric voltage) signal of the vibration sensor A circuit, an integrating circuit, and a filter circuit are shown in FIG.
[0051]
In the circuit of FIG. 5, when a rectangular wave signal is input from the MCU 50 of the washing machine, the piezoelectric diaphragm Bz1 functions as a piezoelectric buzzer, and otherwise functions as a vibration sensor and a sound collector. When the piezoelectric diaphragm Bz1 functions as a vibration sensor and a sound collector, it is necessary to appropriately amplify the signal of the piezoelectric diaphragm Bz1, apply integration, filter, etc., and output it. These will be described below.
[0052]
When the piezoelectric diaphragm Bz1 is used as a vibration sensor, a piezoelectric buzzer, and a sound collector, the problem is a parallel resistance connected to the piezoelectric diaphragm Bz1. Since the piezoelectric element 21 is made of ceramics, it can be regarded as a capacitor having a small capacity (several thousand pF). This internal resistance is several [MΩ].
[0053]
Therefore, when used as a piezoelectric buzzer, a resistor (for example, 1.5 [kΩ]) that is somewhat lower than a few [MΩ] is inserted in parallel, and a voltage is generated by passing a current through this resistor. If it is not applied to the plate Bz1, the sound cannot be produced with sufficient sound pressure. In addition, when using as a vibration sensor, if a sufficiently large resistor (for example, 1 [MΩ]) is not inserted in parallel, the potential may float during amplification or the signal (reverse piezoelectric depending on the strain) Voltage) is attenuated.
[0054]
Transistors Q1 and Q3 in FIG. 5 are drive circuits that generate voltage by applying a voltage to the piezoelectric diaphragm Bz1 (acting as a piezoelectric buzzer). The transistor Q2 functions as a switch for switching whether the piezoelectric diaphragm Bz1 functions as a piezoelectric buzzer or a vibration sensor. By switching the above-described two types of parallel resistors, the piezoelectric diaphragm Bz1 is devised so that the maximum performance can be exhibited when used for each application.
[0055]
When there is no input signal from the MCU 50, the transistors Q1, Q2, and Q3 are off, and the piezoelectric diaphragm Bz1 has a parallel resistor R10. One end of the piezoelectric diaphragm Bz1 is connected to a connection point between resistors R8 and R9 that divide the power source of the power source Vcc2 and an inverting input terminal − of the operational amplifier Op1-A, and the other end is a non-inverting input terminal of the operational amplifier Op1-A. Connected with +. That is, the resistor R10 is effective as the parallel resistance of the piezoelectric diaphragm Bz1. From the above description, the resistor R10 has a sufficiently large resistance value, for example, about 1 [MΩ].
[0056]
When the audible sound frequency rectangular wave (for example, 2 [kHz]) for operating the buzzer is input from the main MCU 50 of the washing machine, the NPN transistor Q1 switches at the same frequency as the input waveform. When the transistor Q1 is turned on, a potential difference is generated between the emitter and base of the PNP transistor Q3, so that the transistor Q3 is turned on. When Q1 is turned off, the transistor Q3 is similarly turned off. Therefore, the transistor Q3 switches at the same frequency as the input waveform, like the transistor Q1.
[0057]
A capacitor C1 is provided between the base and ground of the NPN transistor Q2, and a low-pass filter (low-pass filter) is constituted by the resistor R5 and the capacitor C1, or the resistor R6 and the capacitor C1. The time constant of this low-pass filter is appropriately selected, and when a rectangular wave is input to the input, the transistor Q2 is always turned on. Here, since the resistor R7 is sufficiently smaller than the internal resistance of the resistor R10 and the piezoelectric diaphragm Bz1, the resistor R7 is always effective as a parallel resistor of the piezoelectric diaphragm Bz1 when the buzzer is sounded. . At this time, from the above description, it is assumed that the resistance value is somewhat lower than the internal resistance of the piezoelectric diaphragm Bz1, for example, 1.5 [kΩ].
[0058]
In FIG. 5, operational amplifiers Op1-A and Op1-B perform differential amplification of signals when the piezoelectric diaphragm Bz1 is used as a vibration sensor or a sound collector. As the operational amplifier for Op1, a single power supply (Vcc2) is used. This is to save the trouble of creating a new negative power supply on the circuit of the washing machine.
[0059]
Since a single power supply operational amplifier is used, when the signal is amplified, the voltage of the power supply Vcc2 is divided by resistors R8 and R9 to create a reference voltage of Vcc2 / 2 and input to the operational amplifier as a bias voltage, so that the voltage Vcc2 / 2 is centered. Output of 0 to Vcc2 is obtained.
[0060]
As described above, the voltage Vcc2 / 2 is also input to the piezoelectric diaphragm Bz1. This is to prevent the DC voltage of Vcc2 / 2 from being constantly applied to the piezoelectric diaphragm Bz1 because the bias of the voltage Vcc2 / 2 is always applied to the input of the operational amplifier of the single power supply. When a DC voltage is applied to the piezoelectric element 21, a thin film such as silver deposited on the surface of the piezoelectric element 21 may cause migration, which is prevented.
[0061]
A high input impedance differential amplifier was constructed for signal amplification. In signal amplification of minute signals such as the piezoelectric element 21, it is necessary to pay sufficient attention to noise countermeasures. In a washing machine, there are many noises such as noise of an AC power source and switching noise of an inverter that is a motor drive circuit. Since the wiring of the vibration sensor 16a needs to be drawn for a relatively long time, measures against these noises cannot be avoided. Since differential amplifiers have the advantage of being able to remove common mode noise, they are frequently used in sensor circuits that handle minute signals. However, in a normal differential amplifier configured using only one operational amplifier, the input impedance is determined by a resistor connected to the input terminal of the operational amplifier and a signal source. Since the internal resistance of the piezoelectric diaphragm Bz1 is as large as several [MΩ], unless the input impedance is increased, the input signal may be reduced and buried in noise.
[0062]
Further, if the feedback resistance is increased to increase the amplification degree too much, it is likely to be affected by induced noise. Therefore, it is disadvantageous in terms of the double of input impedance and amplification factor.
[0063]
In order to solve this, a differential amplifier is configured using two operational amplifiers, Op-amps Op1-A and Op1-B. The differential inputs are all non-inverting input terminals of the operational amplifier, and the input impedance is the input impedance itself of the operational amplifier. Further, since the transistor Q3 is turned on and off during the sound generation operation, the voltage of the power source Vcc1 is applied to the non-inverting input terminal. Therefore, appropriate resistors R12 and R15 are inserted into the non-inverting input terminal for protection. It is.
[0064]
Further, in order to remove 50 [Hz] and 60 [Hz] inductive noise caused by the AC power supply, which cannot be completely removed by the differential amplifier, the operational amplifier Op1-C constitutes a notch filter (band reject filter).
[0065]
Further, an inverting amplifier is added so as to match the level of the A / D converter terminal of the MCU 50 of the washing machine with the operational amplifier Op1-D. The input of the operational amplifier Op1-D cuts the direct current with the capacitor C11.
[0066]
This is because, when the case of the vibration sensor 16a is deformed due to temperature, a static stress is applied to the piezoelectric diaphragm Bz1, a DC potential is generated in the piezoelectric element 21, and the output potential of the inverting amplifier fluctuates. ) To prevent clipping. Another reason is to prevent the oscillation component (alternating current component) from being clipped due to fluctuations in the output potential of the inverting amplifier due to the offset voltage of the operational amplifier or the variation of the resistors.
[0067]
Since the signal obtained from the piezoelectric diaphragm Bz1 is an acceleration signal, it has frequency dependence, and the output increases as the frequency increases. To remove this, it is necessary to apply integration. The signal obtained from the piezoelectric diaphragm Bz1 becomes a signal proportional to the speed by one integration, and a signal proportional to the vibration by two integrations. Integration is performed by adding capacitors C3 and C8 in the amplifier circuit in FIG. In FIG. 5, the integration is doubled, and ideally, the acceleration information of vibration is amplitude information.
[0068]
At this time, the frequency range to be integrated was set to about 5 [Hz] or more. This is because the vibration of the outer tub 4 at the primary resonance frequency and the secondary resonance frequency in the washing machine or the collision between the outer tub 4 and the washing machine housing 1 is detected as the magnitude of the impact by taking out the acceleration signal as it is. This is because of this. That is, when the spin speed is 5 [Hz] or less, the collision between the outer tub 4 and the washing machine casing 1 is detected, and after dehydration is started, the amplitude of vibration is detected. This is due to the following reason.
[0069]
As frequency bands of the vibration sensor 16a and the vibration sensor circuit 55 for monitoring the vibration of the washing machine outer tub 4, the primary resonance frequency of the washing machine outer tub 4 is about 1 to 2 [Hz], and the secondary resonance frequency is 3 to 3. If it is about 4 [Hz] and the maximum dehydration rotation frequency is about 20 [Hz], 1 [Hz] to 20 [Hz] may be sufficient.
[0070]
However, the piezoelectric diaphragm Bz1 detects acceleration, and at a frequency of 1 to 4 [Hz], since the acceleration is small even if the vibration amplitude is large, the voltage output of the piezoelectric diaphragm Bz1 is small. For this reason, it is necessary to increase the circuit amplification degree. (Integration will reduce the amplification above the corner frequency.)
[0071]
Conventionally, the shake switch 17, which is often used as an abnormal vibration detection device for a washing machine, detects vibration amplitudes (vibration amounts) of extremely low frequency primary resonance and secondary resonance, which is difficult to detect acceleration values, and is dehydrated. Judgment was made on whether or not to start the process.
[0072]
Capacitors C3 and C8 are not required when vibration acceleration is output without applying double integration. However, since the vibration acceleration output depends on the dehydration frequency (rotation speed) as described above, when this value is used for control or the like, care must be taken such as correction with the frequency (rotation speed). In this example, it is handled as vibration amplitude output after double integration.
[0073]
Furthermore, Op2-A and B operational amplifiers connected to the differential amplifier circuit constitute a band-pass filter. At this stage, only a signal having a frequency in the audible sound region of the signal amplified by the high input impedance differential amplifier is taken out. Here, the passband frequency of the bandpass filter is set in the audible sound region (about 300 to 3 [kHz]). This is a circuit for realizing the above-described sound collector.
[0074]
The vibration sensor circuit 55 described above can drive the vibration sensor, the piezoelectric buzzer, and the sound collector or amplify the vibration detection output.
[0075]
The vibration sensor 16a and the vibration sensor circuit 55 are mounted on the washing machine of FIG. The vibration sensor 16 a is installed in the outer tub 4 in order to directly measure the vibration of the outer tub 4.
[0076]
In the washing machine, the cloth is entangled during washing and the washing water is drained for dehydration, so that the cloth does not settle evenly on the bottom surface of the inner tub (washing and dewatering tub) 5. In the dehydration, centrifugal dehydration is performed while the fabric is stuck around the inner tub (dehydration tub) 5 in a state where the cloth is offset. Due to the deviation of the cloth, the inner tub 5 rotates at high speed in an unbalanced state and vibrates. This vibration causes the outer tub 4 to vibrate as a reaction. The vibration of the outer tub 4 is detected by the vibration sensor 16a.
[0077]
6A, 6B, 6C, and 6D are schematic views showing a representative example of the aforementioned unbalance that occurs in the washing machine shown in FIG. The actual imbalance has a certain extent, but for simplicity, it is represented by an equivalent mass point.
[0078]
In the washing machine as shown in FIG. 1, when the imbalance due to the cloth piece occurs only in the upper part of the inner tub as shown in FIG. 6A, it becomes only in the lower part of the inner tub as shown in FIG. 6B. When generated, as shown in FIG. 6C, when generated at the same position in the upper and lower sides of the inner tank (in phase), as shown in FIG. 6D, when generated at the position opposite to the upper position of the inner tank, as shown in FIG. There are four typical types. In FIG. 6, 18 is the unbalanced mass.
[0079]
In the case of (1), the upper part of the outer tank vibrates violently, and the lower part has less vibration than the upper part. In the case of (2), the lower part vibrates particularly vigorously, but the upper part does not reach the lower part, but vibrates. In the case of (3), the upper part and the lower part are shaken in the same phase, and a large vibration is generated. In particular, the vibration in the primary mode is large (see FIG. 7B). In the case of {circle around (4)}, the top and bottom swings in opposite phases, a node is formed at the center, and the top and bottom vibrates greatly (see FIG. 7C).
Therefore, in order to install the vibration sensor 16a in the outer tub 4, it is preferable to avoid the vicinity of the upper and lower centers of the outer tub 4 where nodes can be formed.
[0080]
FIG. 7A is a diagram of typical vibration characteristics at the time of dewatering of the washing machine outer tub 4 due to these imbalances. FIG. 7B shows the vibration state of the inner tank 5 and the outer tank 4 in the primary mode (resonance) (about 1 [Hz] to 2 [Hz]), and FIG. 7C is in the secondary mode (resonance). The vibration state of the inner tank 5 and the outer tank 4 at 3 [Hz] to 4 [Hz] is shown. FIG. 7D shows the vicinity of the third mode (resonance) (about 12 [Hz] to 15 [Hz]). The vibration state of the tank 5 and the outer tank 4 is shown.
[0081]
When dehydration is started, first-order mode (resonance) vibration is first generated around 100 revolutions per minute. In the primary mode (resonance), the top and bottom vibrate in the same phase (translate). This is a translational vibration due to the pendulum motion of the suspension rod 10 depending on the outer tub 4. When the rotation further increases, secondary mode (resonance) vibration occurs around 200 rotations per minute. In the secondary mode (resonance), the top and bottom vibrate in a reverse phase (conical). This is a conical vibration that occurs because the lower center of gravity of the outer tub 4 is supported by the suspension rod 10.
[0082]
After this, the vibration is once reduced. In the vicinity of the third-order mode (resonance) where the rotation exceeds 1000 revolutions per minute, the inner tank 5 and the outer tank 4 vibrate in opposite phases while the upper and lower sides vibrate in opposite phases (conical). At this rotational speed, the outer tub 4 and the inner tub 5 of a general washing machine do not move as rigid bodies, and the inner tub 5 and the outer tub 4 vibrate in opposite phases. For this reason, the inner tank 5 and the outer tank 4 may come into contact with each other and generate abnormal noise.
[0083]
Further increase in the number of rotations causes a large resonance at the natural frequency of the outer tub 4. This is called a third-order mode (resonance). The normal dehydration rotational speed is limited to a rotational speed lower than the tertiary mode.
[0084]
In FIG. 1, only one vibration sensor 16 a is arranged on the upper part of the washing machine outer tub 4. This is due to the following reasons.
[0085]
The center of gravity of the washing machine in FIG. 1 is located below the center of the outer tub 4, the vicinity thereof is supported by the suspension rod 10, and is suspended from the outer frame (housing) 1. Therefore, it can be said that the vibration of the lower part is suppressed relatively well by the damper 11, whereas the vibration of the upper part of the water tank at a position far from the center of gravity and the support point is greatly generated. However, when a large imbalance occurs only in the lower portion, the lower amplitude becomes larger than the upper amplitude.
[0086]
However, the imbalance that occurs during dehydration in the actual washing process is mostly generated in the same or opposite phase up and down except when the laundry capacity is small. When the capacity is small, there is little unbalance generated. In a dangerous vibration where abnormal noise occurs, the upper part shakes more than the lower part. For the same reason, when the outer tub 4 first collides with the outer frame (housing), the upper portion of the outer tub 4 often hits. Therefore, it is desirable to arrange the vibration sensor in the upper part of the outer tank in the vertical direction.
[0087]
8A, B, C, and D show the relationship between vibration and noise in the upper and lower portions of the outer tub 4 in various unbalanced states near the cloth pieces, which are obtained by experiments. Regarding the vibration, the vertical direction (vertical direction, the direction parallel to the rotation axis of the inner tank 5) and the horizontal direction (left-right direction, radial direction of the outer tank 4) are shown separately. 8A shows the relationship between upper lateral vibration and noise, FIG. 8B shows the relationship between upper longitudinal vibration and noise, FIG. 8C shows the relationship between lower lateral vibration and noise, and FIG. 8D shows the relationship between lower vertical vibration and noise. From this, it can be seen that the noise caused by the vibration caused by the cloth imbalance is not correlated with the transverse vibration but correlated with the longitudinal vibration.
[0088]
FIG. 9A shows the relationship between dehydration speed and noise in four types of unbalanced states obtained by experiments. FIG. 9B shows the relationship between the vertical vibration amplitude and noise in the upper part of the outer tub 4 at the rotation speeds of 600, 750, and 850 rpm. The solid line shows a linear approximation of the data at each rotational speed. Furthermore, the arrow line in the figure shows the transition by increasing the number of rotations of the data.
[0089]
From FIG. 9A, it can be seen that the noise is proportional to the spin speed and the proportionality factor is almost the same in each unbalanced state (the four lines are parallel). As the spin speed increases by 100 rpm, the noise increases by about 3 dB. This increase is due to an increase in vibration amplitude.
[0090]
From FIG. 9B, it can be seen that the vertical vibration amplitude of the upper part of the outer tub 4 and the noise are also in a proportional relationship, and the vibration amplitude increases as the number of rotations increases, thereby increasing the noise. In the range of 600 to 850 rpm, when the rotational speed increases by 100 rpm, the vibration amplitude increases by 1 mmp-p and the noise increases by 3 dB. (In the figure, threshold values A1, A2, B1, B2, etc. used for explanation of the dehydration process control described later are also shown.)
[0091]
From the above, in order to control the dehydration rotation speed using the vibration sensor 16a for the purpose of suppressing noise, the vibration sensor 16a detects vibration in which the polarization direction of the piezoelectric element 21 is parallel to the rotation axis direction of the inner tank 5, that is, in the longitudinal direction. It is good to install. In this case, one vibration sensor 16a may be installed either above or below the outer tub 4. Then, based on this longitudinal vibration, it can be understood that control may be performed based on the relationship between the spin speed and noise and the relationship between longitudinal vibration and noise in FIGS. 9A and 9B. An actual control example will be described later.
[0092]
FIG. 10 shows details of installation of the vibration sensor 16a in FIG. The vibration sensor 16a is installed outside the upper portion of the outer tub 4 so that the polarization direction of the piezoelectric element 21 (ab line in the figure) is parallel to the rotation axis direction of the inner tub 5, that is, detects the vibration in the vertical direction. The installation at the top is also advantageous in terms of the sound pressure that the user listens to when functioning as a piezoelectric buzzer.
[0093]
FIG. 11 shows another example of vibration sensor installation. This is a case where the vibration sensor 16a is installed above the upper part of the outer tub 4. As in FIG. 10, the vibration sensor 16 a is installed so that the polarization direction of the piezoelectric element (ab line in the figure) is parallel to the rotation axis direction of the inner tank 5, that is, detects vibration in the vertical direction. In this case, the vibration sensor 16a is preferably installed around the upper circumference of the outer tub 4 where the vibration level is as large as possible.
[0094]
FIG. 12 shows another example of vibration sensor installation. This is a case where the vibration sensor 16a is installed on the bottom surface of the lower part of the outer tub 4. As in FIG. 10, the vibration sensor 16 a is installed so that the polarization direction of the piezoelectric element 21 (ab line in the figure) is parallel to the rotation axis direction of the inner tank 5, that is, detects vibration in the vertical direction. In this case, the vibration sensor 16a is preferably installed around the circumference of the bottom surface of the outer tank 4 having a large vibration level (away from the inner tank rotation axis).
[0095]
The vibration sensor 16a shown in FIGS. 10 to 12 is as shown in FIG. 3. However, in the case of the vibration sensor shown in FIG. 4 or the vibration sensor module shown in FIG. What is necessary is just to install so that a vibration parallel to an inner tank rotating shaft direction, ie, a vertical direction, may be detected.
[0096]
FIG. 13 shows a structure of a vibration sensor 16a different from the structure of FIGS. Parts corresponding to those in FIGS. 3 and 4 are denoted by the same reference numerals. In the present vibration sensor, the lead wire 25 connected to the piezoelectric vibration plate Bz1 of FIGS. FIG. 13A shows an overview of the vibration sensor, FIG. 13B shows details of attachment of the electrode / support leg, and FIG. 13C shows a vibration sensor module in which the vibration sensor is fixed in the case together with the vibration sensor circuit and modularized.
[0097]
A plate spring-like metal plate to be the electrode and support legs 31 and 32 is attached via the piezoelectric diaphragm case 23. The metal plate is formed by cutting the electrode portions 31a and 32a and the support leg portions 31b and 32b from a single leaf spring. However, this is achieved by making a cut without completely separating the two. The electrode portions 31a and 32a are sufficiently thinner than the support leg portions. These are integrated at the base, but are fixed to the piezoelectric diaphragm case 23 using the integrated portion.
[0098]
Therefore, a structure for mating with each of the metal plate attachment portion and the metal plate base portion of the piezoelectric diaphragm case 23 is provided. After the electrode / support legs 31, 32 and the piezoelectric diaphragm case 23 are mated, the tips of the electrode portions 31a, 32a are soldered to the piezoelectric diaphragm Bz1.
[0099]
The electrode / support legs 31 and 32 are soldered to the predetermined positions of the circuit board 33 at the tips of the support legs 31b and 32b of the two electrode / support legs 31 and 32, and the vibrations of FIG. A sensor circuit 55 is mounted. These are placed in a storage case 34 to be modularized.
[0100]
The storage case 34 has a circular rib 35 for fixing the vibration sensor 16a on the inner side of the upper surface, in which the piezoelectric diaphragm case 23 is accommodated. This prevents the vibration sensor 16a from swinging left and right and applying excessive repetitive stress to the electrode / support legs 31 and 32. A waterproof resin 36 is coated on the upper and lower surfaces of the circuit board 33 so as to cover the electronic components and the wiring pattern. A connector 37 is mounted on the circuit board 33, and a power source and a signal line 38 to the vibration sensor circuit 55 are drawn from the storage case 34. The storage case 34 is provided with a screw hole 39 for installing it with a screw or the like.
[0101]
Thus, by integrating the vibration sensor 16a and the vibration sensor circuit 55 into the storage case 34, the vibration sensor 16a and the vibration sensor circuit 55 are connected in the shortest time, and the output signal of the vibration sensor 16a is amplified. Low output impedance signal. As a result, even when the output line is extended and routed, noise mixing into the AD input terminal of the main MCU 50 can be suppressed. That is, it is possible to facilitate mounting design on a washing machine.
[0102]
FIG. 14 is a schematic view of the example of FIG. The vibration sensor 16 a is disposed in the vicinity of any one of the suspension bars 10 that suspend the outer tub 4 from the four corners of the outer frame (housing) 1.
[0103]
If there is no interference with the outer frame (housing), the outer tub 4 rotates in an outer frame (housing) 1 so as to draw an ellipse or a circle as viewed from above. If the outer tub 4 interferes with the outer frame (housing) 1 (or interferes with the damper 11 attached to the outer frame 1), vibration that is biased in the front-rear direction or the left-right direction of the washing machine occurs. However, depending on the installation position of the vibration sensor 16a, the magnitude of vibration may not be correctly observed due to interference with the outer frame 1. As shown in FIG. 14, this can be avoided by arranging vibration sensors at one of the four corners around which the outer tub is suspended or at the periphery thereof (placed on the diagonal line of the washing machine). This arrangement method also has an advantage of reducing the risk of collision between the vibration sensor 16a and the outer frame.
[0104]
In addition, regarding the collision detection between the outer tub 4 and the outer frame 1, when the outer tub 4 swings in the front-rear direction or the left-right direction of the washing machine, the lever 17 a of the conventional shake switch 17 has the outer tub 4 on the lever 17 a. However, in this example, since the vibration of the outer tub is detected by using the vibration sensor 16a, the above-described problem can be avoided.
[0105]
Next, an example of dehydration process control for suppressing noise according to this example will be described with reference to FIG.
The flowchart of FIG. 15 is a flowchart for controlling the dehydration process of the washing machine. It is assumed that the above-described means for detecting vibration, that is, the vibration sensor 16a and the vibration sensor circuit 55 are provided. Such a dehydration process of washing is executed by the washing machine control unit by a program stored in the MCU 50 in advance. In this dehydration process, based on information from the vibration sensor 16a, the collision between the outer tank and the outer frame is monitored in the initial stage of dehydration, and the vibration of the outer tank is monitored in the latter stage of dehydration.
[0106]
In FIG. 15, step S6 is an interrupt process periodically generated by a timer interrupt or the like, and separately from the flow starting from step S1, in the background of the dehydration process control, the motor rotation speed and the outer tank vibration from the vibration sensor 16a. In addition to obtaining information, checking elapsed time, etc., it also commands the control circuit 51 that controls the motor. Information acquisition from the vibration sensor 16a is obtained by reading the signal from the output terminal A56 of the vibration sensor circuit 55 to which the vibration sensor 16a is connected at the AD input terminal A57 of the MCU 50, and obtaining the signal amplitude from the maximum and minimum values of the signal. is there. This signal amplitude corresponds to the longitudinal vibration amplitude of the outer tub.
[0107]
When dehydration is started in step S1, the rotational speed is increased to a predetermined dehydration rotational speed N1 (steps S2 and S3). This is a rotation speed close to the primary resonance frequency or the secondary resonance frequency. When the number of revolutions reaches N1, if the number of collisions between the outer tub 4 and the outer frame 1 up to that time is greater than the predetermined number Cn (step S4), it is determined that the imbalance due to the cloth piece is large and dehydration is started. (Stopping the rotation of the inner tub 5) (step S5), rotating the rotor blades, loosening the clothes in the inner tub 5 and reducing the imbalance (referred to as rebalancing) (step S6).
[0108]
Here, the number of collisions between the outer tub 4 and the outer frame 1 is obtained from information from the shake switch 17, that is, the number of times the microswitch is opened and closed. Or you may detect the collision sound of the outer tank 4 and the outer frame 1 with a sound collector. Specifically, the signal from the output terminal B58 of the vibration sensor circuit 55 is read by the AD input terminal B59 of the MCU 50, the signal amplitude is obtained from the maximum and minimum values of the signal, and this is compared with a predetermined threshold value, and exceeds the threshold value. This is done by counting this number of times as a collision.
[0109]
In the vicinity of the secondary resonance frequency (longitudinal vibration component is large), an abnormally large longitudinal vibration that is in contact with the outer tub 4 can be detected even with the vibration detection output of the vibration sensor 16a. As with the collision sound, a signal from the output terminal A56 of the vibration sensor circuit 55 may be read by the AD input terminal A57 of the MCU 50 and compared with a predetermined threshold value to detect a collision at the secondary resonance.
[0110]
Here, if the imbalance does not become small after many retries (the number of tries is equal to or greater than the predetermined number X), the dehydration process is stopped as a dehydration error (steps S8 and S18).
[0111]
If it is determined that the unbalance is not excessive, the rotation is increased again to a certain rotation speed N2 (steps S7 and S9). Here, the vibration amplitude from the current vibration sensor 16a is compared with predetermined thresholds A1 and A2 (steps S10 and S11), noise due to the generated imbalance is estimated, and the maximum dewatering speed Nm and dewatering time Td are set. Decide (Step S12, Step S13, Step S14). Next, how to determine the threshold will be described.
[0112]
Now, the process of assigning N2 = 600 rpm and distributing the maximum dehydration speed of the dehydration process to Nm0 = 610 rpm, Nm1 = 750 rpm, and Nm2 = 850 rpm with two threshold values A1 and A2 will be described with reference to FIG. 9B.
[0113]
In FIG. 9B, an alternate long and short dash line parallel to the data transition (solid arrow) is drawn so as to pass through the intersection of the approximate straight line of the 850 rpm data and the noise 50 dB line. Similarly, an alternate long and short dash line is drawn that passes through the intersection of the approximate line of 750 rpm data and the noise 50 dB line. An arrow is dropped on the vibration amplitude axis perpendicularly from these intersections, and the vibration amplitude values indicated by the arrow are B1 and B2.
[0114]
Also, a solid line arrow is drawn vertically on the vibration amplitude axis from the point where these alternate long and short dash lines intersect with the approximate straight line of 600 rpm data, and the vibration amplitude value indicated by this arrow is the threshold value. Indicated in the figure as A1 and A2.
[0115]
This means the following: Data having a vibration amplitude value of A1 at 600 rpm increases the vibration amplitude from A1 to B1 when the rotational speed increases to 850 rpm, and accordingly increases the noise from 42 dB to 50 dB.
[0116]
In order to suppress the noise at the maximum dewatering speed Nm (= Nm0 or Nm1 or Nm2) to 50 dB or less, when the detected vibration amplitude is smaller than A1 = 1.1 mmp-p, the maximum dewatering speed is set to Nm2 = 850 rpm, 1. From 1 mmp-p to 3.3 mmp-p, the maximum dewatering speed is set to Nm1 = 750 rpm, and at 3.3 mmp-p and higher, the maximum dewatering speed is set to Nm0 = 610 rpm, and the noise can be reduced to 50 dB or less. Become.
[0117]
In order to make the dehydration rate the same for the dehydration time Td, Td0 for Nm0, Td1 for Nm1, Td2 for Nm2, and (Td0>Td1> Td2). For example, Td0 = 12 minutes, Td1 = 10 minutes, and Td2 = 8 minutes.
[0118]
The above processing, that is, the processing of classifying the vibration amplitude value from the vibration sensor 16a by the threshold values A1 and A2 and assigning the maximum dewatering speed Nm and the dewatering time Td to each of them is step10 to step14.
[0119]
Next, the voltage to the motor is set so that the maximum dewatering speed is Nm0, Nm1, and Nm2, and the dewatering speed is increased (step S15). Over time, the rotational speed reaches the maximum dewatering rotational speed. Here, the elapsed time is monitored (step S16), and when the dehydration time reaches the set time (Td0, Td1, Td2), the rotation of the motor is stopped (step S17) and the dehydration is terminated (step S18).
[0120]
In the dehydration process of this flowchart, the target noise can be suppressed to 50 dB by adjusting the maximum dehydration rotation speed with the vibration amplitude detected by the vibration sensor.
[0121]
Further, the flowchart of FIG. 16 is a flowchart for controlling another dehydration process of the washing machine. In FIG. 16, the processing units corresponding to those in FIG.
The difference from FIG. 15 is that after reaching the maximum dewatering speed, the dewatering speed is readjusted according to the vibration amplitude.
[0122]
The imbalance due to the laundry during dehydration may change due to a change in the moisture content of the laundry (cotton fibers are difficult to remove moisture, but synthetic fibers are easily removed) and the movement of the laundry. Therefore, using such a method, it is necessary to prevent the vibration amplitude from increasing due to a change in the unbalanced state and resulting noise from increasing. It is important to perform more robust control.
[0123]
Description of corresponding processing with the same reference numerals as in FIG. 15 is omitted. A process (step S19 to step S23) for comparing the vibration amplitude at the current rotation speed with the threshold values B1 and B2 and reducing the current dewatering rotation speed by the set maximum dewatering rotation speed is introduced.
[0124]
The set maximum dewatering rotation speed is determined (steps S19 to S20). When Nm = Nm2, if the vibration amplitude is larger than the threshold value B1 (step S21), the rotation speed is decreased by a predetermined amount Δ, for example, 20 rpm (step S21). S23). Do nothing if: The number of revolutions is reduced by reducing the voltage applied to the motor.
[0125]
Since it takes time for the motor rotation speed to decrease due to inertia, a predetermined waiting time T is inserted. As described above, the threshold value B1 is a vibration amplitude value where the noise is 50 dB when the rotation speed is Nm2. Exceeding this means that the noise exceeds 50 dB.
[0126]
Similarly, when Nm = Nm1, if the vibration amplitude is larger than the threshold B2 (step S22), the rotational speed is decreased by a predetermined amount Δ, for example, 20 rpm (step S23). Do nothing if: Nothing is done when Nm = Nm0.
In the flowchart described above, noise can be suppressed to 50 dB or less even if the unbalanced state changes during the dehydration process.
[0127]
FIG. 17 is a flowchart for controlling another dehydration process of the washing machine. In FIG. 17, processing portions corresponding to those in FIGS. 15 and 16 are denoted by the same reference numerals, and description thereof is omitted.
[0128]
FIG. 17 differs from FIGS. 15 and 16 in that the vibration amplitude is always monitored after the rotation speed exceeds N1, and the dehydration rotation speed is increased or decreased below the maximum dehydration rotation speed by the vibration amplitude.
[0129]
Now, let us consider a control in which the maximum dewatering rotation speed Nmax is set to 850 rpm and the vibration amplitude value B1 (see FIG. 9B) exceeding the noise of 50 dB at this rotation speed is used as a threshold value.
[0130]
When N2 is exceeded, the dehydration speed is further increased (step S7). While monitoring the vibration amplitude from the vibration sensor, it is compared with the threshold value B1 (step S30). If it is smaller than the threshold value B1, the rotational speed is increased by a predetermined amount Δ (step S31). If it is greater than or equal to the threshold value B1, the rotational speed is decreased by Δ (step S32). Then, it is determined whether the current dewatering speed exceeds the maximum dewatering speed Nmax (step S33). If it exceeds, the rotational speed is decreased by Δ (step S32). The above is repeated while monitoring the dehydration time (step S16).
[0131]
As a result, the dewatering speed is limited to the maximum dewatering speed Nmax = 850 rpm, and becomes a steady speed with a noise of 50 dB or less. At this time, the dehydration rotational speed in the steady state takes various values depending on the vibration amplitude, that is, the unbalanced state and amount due to the cloth piece.
[0132]
In FIG. 17, the change amount of the vibration amplitude may be added to the control. This is due to the following reason.
[0133]
As the dehydration speed is increased further, the vibration of the washing machine eventually approaches the resonance point of the third-order mode. This is a vibration in which the inner tub 5 and the outer tub 4 of the washing machine are swung in opposite phases. When the vibration increases, the inner tub 5 and the outer tub 4 collide, the center of rotation of the inner tub 5 is shifted, and the laundry Even if you don't put in, you will have unbalance. At this time, since excessive vibration and noise are generated, it is necessary to prevent such a vibration mode. As the resonance point of the third-order mode is approached, the outer tank vibration increases rapidly.
[0134]
Therefore, the change in vibration is monitored, and when a phenomenon that leads to a rapid increase occurs, control for suppressing the rotation speed is added to the control shown in FIG.
[0135]
Further, the maximum dewatering rotation speed Nmax may be set to a constant value as described above, or may be set to a value corresponding to the amount of cloth by sensing the amount of laundry at the start of washing.
[0136]
Next, a description will be given of control for determining whether a mechanical component has failed using the sound collection function of the vibration sensor 16a.
[0137]
Although various actuators are mounted on the washing machine of FIG. 1, the actual washing machine and the washing and drying machine have more actuators. They can operate independently and are all controlled by the MCU 50.
[0138]
In the washing machine, at the time of course selection / input work at the start of operation, at the time of temporary stop, at the end of operation, etc., a notification sound is transmitted by using the vibration sensor 16a as a piezoelectric buzzer. Further, at the time of dehydration, the vibration of the outer tub 4 is detected, and the above-described control for suppressing the vibration and noise is performed.
[0139]
Furthermore, during the operation of the washing machine, the function as a sound collector is exhibited, and abnormal sounds of various actuators such as a water supply valve, a drain valve, a clutch, and a gear are detected. At this time, it is necessary to detect only abnormal sounds generated from the washing machine without being distracted by ambient noise or the like. This is dealt with by collecting sounds in accordance with the timing at which the MCU 50 controls each actuator because the MCU 50 controls each actuator.
[0140]
If this sound collector is used, it is possible to collect various sounds generated by the actuators of the washing machine. In other words, this can be said to be a sensor capable of detecting noise, and this noise level can detect abnormal operation noise of each actuator and estimate these failures.
[0141]
In addition, since the MCU 50 obtains abnormal noise from each actuator that controls its operation at the control timing, it is possible to specify the source of the abnormal noise. The MCU 50 issues an ON signal of the actuator, starts data acquisition of the sound collector, and acquires an operation sound of the actuator. Subsequently, the actuator off signal is issued, and the data acquisition of the sound collector is stopped. Furthermore, if various abnormal sounds of the washing machine obtained as described above are subjected to FFT or wavelet transform on the software of the MCU 50, various sounds can be decomposed into spectra.
[0142]
At this time, if the natural frequency of the sound generated by each actuator of the washing machine, the sound pressure level in normal operation, etc. are known in advance, the failure of each actuator of the washing machine is determined in more detail by comparison with these. It becomes possible.
[0143]
Conventionally, in failure diagnosis, an electrical detection means is generally taken. This seems to be a preferable method from the viewpoint of cost. However, in such a method, only failure diagnosis of elements with electricity is possible. For example, there are many defects (complaints) related to unpleasant sounds during washing machine operation, such as poor engagement of gears and clutches, abnormal sound of bearings, and frictional noise. If this fault diagnosis is used, the above-mentioned failure can be automatically diagnosed by the washing machine itself without a detailed inspection by the service person, and it is very effective.
[0144]
Next, the case where two vibration sensors 16a and 16b are installed in the outer tub 4 will be described. If there is no interference with the outer frame (housing) 1, the outer tub 4 rotates in an outer frame 1 so as to draw an ellipse or a circle as viewed from above. Therefore, this lateral vibration can be detected by attaching the vibration sensor 16a to the outer tub 4 so that the thickness direction (polarization direction) of the piezoelectric diaphragm coincides with the direction toward the center of the outer tub 4. .
[0145]
As described above, when an imbalance occurs in the vertically opposed position, there is always a point that becomes a vibration node at one point in the outer tub 4. When vibration is measured at such a node, the top and bottom may vibrate violently even though there is almost no amplitude at this point. Accordingly, even when two vibration sensors 16a and 16b are installed, it is effective to attach them one by one to the upper part of the outer tub 4 and the lower part of the outer tub 4 so as not to be affected by such nodes.
[0146]
FIG. 18 shows an installation example of the outer tub 4 of the two vibration sensors 16a and 16b. The vibration sensors 16a and 16b are installed on the same vertical line in the upper and lower portions of the outer tub 4 so as to detect the lateral vibration of the outer tub 4. These vibration sensors 16a and 16b are shown in FIG. 3, but may be those shown in FIGS.
[0147]
FIG. 19 is a block diagram of the washing machine control unit of this example. 19, parts corresponding to those in FIG. 2 are given the same reference numerals, and a vibration sensor circuit 62 is newly added. The piezoelectric sensor 16b is connected to the vibration sensor circuit 62, and the signal output terminal C63 of the circuit is connected to the AD input terminal C64 of the MCU 50.
[0148]
FIG. 20 shows details of the vibration sensor circuit 62. 20, the same reference numerals as those in FIG. 4 denote the same items. The vibration sensor circuit 62 is obtained by removing the piezoelectric buzzer drive circuit, the switching circuit, and the audible sound band-pass filter from the vibration sensor circuit 55 of FIG. It is composed of a differential amplifier that simply amplifies a voltage signal generated in the piezoelectric diaphragm Bz1, a notch filter, and an inverting amplifier having a double integral.
[0149]
Next, the operation of this example will be described with reference to FIG. 18, FIG. 19, and FIG.
[0150]
As described above, the washing machine vibrates in various modes. Since the piezoelectric element is polarized in the thickness direction, such an installation method is nothing other than picking up the lateral component of vibration of the outer tub 4 (vibration in the left-right direction).
[0151]
As described above, when one vibration sensor 16a is installed at the upper part or the lower part of the outer tub 4 so as to detect the longitudinal vibration, the following problems can be considered. When the outer tub 4 strongly generates a conical vibration component (in many cases, secondary mode), the detected value in the vertical direction of the vibration sensor 16a is small, but it is actually a very dangerous vibration state in the horizontal direction. There is a possibility.
[0152]
In general, the level ratio of the vibration amplitude in the vertical direction and the horizontal direction is 1 to 3 or more. Further, it is empirically known that when an imbalance is generated only at the lower part, the vibration amplitude at the upper part of the outer tub 4 is about 1/3 as compared with the vibration amplitude at the lower part of the outer tub 4. This is the same when an imbalance occurs only in the upper part.
[0153]
That is, when only one vibration sensor is attached, the vibration in the lateral direction cannot be detected although it is at a dangerous level such as a collision between the outer frame 1 and the outer tank 4 or a collision between the outer tank 4 and the inner tank 5. There is a possibility that a vibration mode (unbalanced state) exists or a threshold value of a dangerous vibration level is not uniquely obtained (the threshold value is different for each vibration mode).
[0154]
Further, in a washing machine, there are several resonance (mode) points in vibration during dewatering rotation. The primary resonance is a mode in which the upper and lower sides vibrate in the same phase (translational motion), and the secondary resonance is a mode in which the upper and lower sides vibrate in the opposite phase (conical motion). If the vibration sensors 16a and 16b are arranged and the phase of vibration is taken into consideration, this can be easily detected.
[0155]
These problems are solved by the two vibration sensors 16a and 16b installed at the upper and lower portions of the outer tub 4 in FIG. 18, which is constituted by the control unit in FIG. 19 and the vibration sensor circuit 62 in FIG. is there.
[0156]
FIG. 21 shows the relationship between the lateral vibration amplitude at the upper and lower portions of the outer tub 4 and the dehydration speed in the vibration mode caused by the typical cloth-slip imbalance shown in FIG. FIG. 21A shows the upper unbalance, FIG. 21B shows the lower unbalance, FIG. 21C shows the upper and lower in-phase unbalance, and FIG. 21D shows the upper and lower reversed-phase unbalance.
[0157]
The upper and lower vibration amplitude levels are different in each vibration mode. In addition, as shown in FIGS. 22A and 22B, the phase relationship between the upper and lower vibration amplitudes during in-phase and reverse-phase (opposite) imbalances swings up and down in the same phase (translational motion), but in the reverse-phase mode Swings out of phase (conical, pestle movement). In the figure, + indicates the deflection of the outer tub 4 toward the outer frame, and-indicates the deflection in the opposite direction. As described above, the vibration modes can be distinguished by using the level and phase relationship between the upper lateral vibration and the lower lateral vibration from FIGS. Specifically, it is as shown in the flowchart shown in FIG.
[0158]
FIG. 24 shows the relationship between the vibration in the upper lateral direction of the outer tub 4 and the noise in each vibration mode. 24A shows the case of upper unbalance, FIG. 24B shows the case of lower unbalance, FIG. 24C shows the case of upper and lower in-phase unbalance, and FIG. It can be seen that there is a correlation between vibration amplitude and noise within the vibration mode. However, the relationship between vibration amplitude and noise is greatly different in each vibration mode.
[0159]
The relationship between the upper lateral vibration and the noise in FIG. 8A shown in the above example includes all of FIGS. 24A, B, C, and D. Thus, if each vibration mode is combined, that is, if vibration in the lateral direction is detected by only one vibration sensor, there is no correlation with noise. However, as shown in FIGS. 24A, B, C, and D, there is a correlation when viewed for each vibration mode.
[0160]
In this way, the vibrations in the lateral direction are detected by the upper and lower vibration sensors 16a and 16b, and based on this, after determining the vibration mode, that is, the state of the cloth imbalance near the cloth, FIG. Noise can be reduced by grasping the relationship of noise from B, C, and D for each vibration mode, and controlling the dehydration speed based on the vibration amplitude in each vibration mode.
[0161]
FIG. 25 shows a flowchart in which this example is applied to the control shown in FIG. The difference from FIG. 15 is that the vibration mode determination process shown in FIG. 23 is added and that the maximum dewatering rotation and control threshold values are provided in the form of a table for each vibration mode. The basic operation is the same as in FIG.
[0162]
The vibration mode determination process (step S50) is performed at the N2 rotation number, and based on this, the above-described table data is read (step S51), and control is performed in the same manner as in FIG.
The other flow charts for the dehydration control are the same for, for example, FIGS. 16 and 17, and a threshold value for the rotational speed control may be provided for each vibration mode from the vibration mode determination process shown in FIG. 23 and the read table value. .
[0163]
Further, the positions of the two vibration sensors 16a and 16b may be shifted in phase by 90 [deg]. This assumes that the touch around the outer tub 4 is not circular. That is, this is to cope with a case where the vibration in a certain direction is small but the vibration at a position shifted by 90 [deg] is very large.
[0164]
Next, the case where the combined value of the horizontal and vertical vibrations of the outer tub 4 is detected by one vibration sensor 16a will be described.
FIG. 26 shows an installation example in which the vibration sensor 16a of FIG.
[0165]
FIG. 26 is also similar to FIG. 11, but the point different from FIG. 11 is between 0 [deg] to 90 [deg] between the piezoelectric element 21 and the side surface of the outer tub 4 when the vibration sensor 16 a is attached. It is a point to install so as to have an angle. If it arrange | positions in this way, it will become possible to pick up both the vibration of the radial direction (left-right direction) of the outer tank 4, and the vibration of a vertical direction. By doing in this way, the longitudinal vibration and the lateral vibration can be detected at the same time, and the problem of not detecting the lateral vibration in the above example can be solved.
[0166]
FIG. 27 shows a sectional view of another vibration sensor. Rather than tilting the vibration sensor itself as described above, it is more advantageous in terms of space and stability required for installation to tilt and fix the piezoelectric diaphragm shown in FIG.
[0167]
The vibration sensor of FIG. 27 has the piezoelectric diaphragm described in FIGS. However, in FIG. 27, the lead wire 25 of the piezoelectric diaphragm is soldered directly to the thin film 21 a and the metal plate 22. The piezoelectric diaphragm is supported and enclosed by the lower case 41 and the upper case 42. This vibration sensor is attached to the object of vibration measurement at the right end (lower case 41) in the figure.
[0168]
As is clear from the figure, the piezoelectric diaphragm is inclined with respect to the mounting surface and elastically supported by the lower case 41 with silicon rubber or the like. Since the piezoelectric element 21 is polarized in the thickness direction, it generates a voltage mainly proportional to the deflection in the thickness direction. For example, if the piezoelectric diaphragm is installed horizontally with respect to the mounting surface, only acceleration acting in a direction perpendicular to the mounting surface can be measured.
[0169]
However, by installing the piezoelectric diaphragm in an inclined manner with respect to the attachment surface as in this example, it is possible to measure not only the direction perpendicular to the attachment surface but also the horizontal acceleration. In a vertical fully automatic washing machine, in the primary resonance, the top and bottom vibrate in the same phase, and the entire outer tub vibrates in translation (transverse vibration), whereas in the secondary resonance, the top and bottom vibrate in the opposite phase, The outer tub 4 causes conical vibration (vertical vibration). The structure shown in this example is a device for dealing with such detection of vertical and lateral vibrations.
[0170]
In the above example, the resultant force due to the acceleration in the horizontal direction and the vertical direction acts on the piezoelectric diaphragm, so that various vibrations can be detected as they are. At this time, by changing the angle of the piezoelectric element 21 to be installed, the sensitivity to vibrations in the left and right directions and the up and down directions can be adjusted. The installation angle is determined with careful attention to what kind of vibration component you want to obtain.
[0171]
Of course, the present invention is not limited to the above-described examples, and various other configurations can be adopted without departing from the gist of the present invention.
[0172]
【The invention's effect】
As described above, according to the present invention, it is possible to keep the cost at the time of sensor introduction low by using a vibration sensor having an inexpensive piezoelectric diaphragm as a core. The vibration sensor is used to control vibration and noise to provide a washing machine with low vibration and noise.
Furthermore, the contact between the outer tub and the inner tub can be prevented to improve the reliability.
[0173]
In addition, according to the present invention, a mechanism for switching the parallel resistance of the piezoelectric element is provided by the vibration sensor circuit, and the piezoelectric diaphragm case is designed as a resonator, so that the conventional piezoelectric buzzer for notification is used and the piezoelectric buzzer and the vibration are designed. It is possible to use both the detection device and the audible sound collector. Accordingly, vibration detection is possible without adding a piezoelectric diaphragm or a case that encloses the piezoelectric diaphragm as a new sensor, and the cost can be reduced.
[0174]
Furthermore, according to the present invention, failure diagnosis of each actuator can be performed using the sound collecting function. This makes it possible to perform failure diagnosis of parts that could not be diagnosed by a conventional electrical method, and it becomes a more effective failure diagnosis system when used together with an electrical method.
[0175]
The vibration is monitored using the vibration sensor as in the present invention, and the unbalance amount generated in the inner tank is estimated to determine the maximum dehydration rotation speed and dehydration time, and the dehydration operation is performed according to this. This makes it possible to provide a dehydration operation that does not deteriorate the dehydration rate while suppressing excessive vibration and noise during dehydration.
[0176]
In addition, according to the present invention, the vibration level is constantly monitored to stop when a sudden rotation speed fluctuation (abnormal vibration) occurs. This is effective as a product fail-safe function.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an interior of a vertical fully automatic washing machine showing an example of an embodiment of a washing machine of the present invention.
FIG. 2 is a configuration diagram illustrating an example of a control device of a vertical fully automatic washing machine.
FIGS. 3A and 3B show examples of a vibration sensor, a piezoelectric buzzer, and an audible sound collector, wherein A is a top view and B is a cross-sectional view along line BB.
FIGS. 4A and 4B show examples of a vibration sensor, a piezoelectric buzzer, and an audible sound collector, in which A is a top view and B is a cross-sectional view along the line BB. FIG.
FIG. 5 is a connection diagram illustrating an example of a vibration sensor circuit.
FIG. 6 is a diagram for explaining an unbalance occurrence position in the washing machine.
FIG. 7 is a diagram for explaining vibration characteristics of an outer tub of a washing machine.
FIG. 8 is a diagram showing the relationship between vibration and noise of the washing machine outer tub.
FIG. 9 is a diagram showing the relationship between the washing machine dewatering speed and noise.
FIG. 10 is a cutaway sectional view showing an example of vibration sensor arrangement on the upper side surface of the outer tub.
FIG. 11 is a cutaway sectional view showing an example of a vibration sensor arrangement on the upper surface of the upper part of the outer tub.
FIG. 12 is a cutaway sectional view showing an example of a vibration sensor arrangement on the bottom surface of the outer tub.
13A and 13B show examples of a vibration sensor and a vibration sensor module, in which A is a perspective view of the vibration sensor, B is a cross-sectional view of the main part of FIG. A, and C is a cross-sectional view of the vibration sensor module.
14 is a cross-sectional view of FIG.
FIG. 15 is a flowchart showing an example of dehydration process control.
FIG. 16 is a flowchart showing another example of the dehydration process control.
FIG. 17 is a flowchart showing another example of dehydration process control.
FIG. 18 is a cutaway sectional view showing an example of vibration sensor arrangement on the upper and lower side surfaces of the outer tub.
FIG. 19 is a configuration diagram showing a control device of a vertical fully automatic washing machine of another example of the present invention.
FIG. 20 is a connection diagram illustrating another example of a vibration sensor circuit.
FIG. 21 is a diagram for explaining the vertical vibration of the outer tub in a typical unbalanced cloth piece.
FIG. 22 is a diagram for explaining the lateral vibration signals of the upper and lower outer tubs.
FIG. 23 is a flowchart illustrating an example of vibration mode determination.
FIG. 24 is a diagram for explaining the relationship between vibration and noise of the washing machine outer tub in each imbalance.
FIG. 25 is a flowchart showing another example of dehydration process control.
FIG. 26 is a cutaway sectional view showing an example of vibration sensor arrangement on the upper surface of the outer tub.
FIG. 27 is a cross-sectional view showing another example of a vibration sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Outer frame (housing | casing), 4 ... Outer tank (water tank), 5 ... Inner tank (washing tank), 16a, 16b ... Vibration sensor, 21 ... Piezoelectric element, 21b ..Waterproof material, 22 ... Metal disk, 23 ... Piezoelectric diaphragm case, 24 ... Sensor case cover, 25 ... Lead wire, Bz1 ... Piezoelectric diaphragm, 31, 32 ... Electrode and supporting leg of piezoelectric diaphragm, 55... Vibration sensor circuit A, 62.

Claims (3)

An outer tank that is a water receiving tank suspended in a swingable manner within the housing, an inner tank that is rotatable about a rotation axis provided in a vertical direction of the outer tank, and a motor that rotates the inner tank. A vibration sensor comprising: a piezoelectric diaphragm comprising a piezoelectric element and a metal plate to which the piezoelectric element is bonded; and a case for supporting the outer periphery of the piezoelectric diaphragm and incorporating the piezoelectric diaphragm in a water seal. , the polarization direction of the piezoelectric element is placed in parallel with the axis of rotation of the inner tub at the top or bottom of the outer tub, the case, the acoustic resonance space resonating audible vibration sound of the metal plate It is composed of a cylindrical case with one end open and has a vibration sensor circuit to which the piezoelectric element is connected. The vibration sensor circuit has two types of resistors having different resistance values, and is contrary to the case of producing sound by the normal piezoelectric effect. Detect vibration acceleration due to piezoelectric effect In the case, and switches the connection of the two resistors as small resistor resistance value is connected in parallel to the piezoelectric element than the case of detecting the vibration acceleration in the case of pronunciation Washing machine. 2. The washing machine according to claim 1, further comprising a vibration sensor circuit to which the piezoelectric element is connected, the vibration sensor circuit, a differential amplifier for amplifying a signal of the piezoelectric element, and an output of the differential amplifier. A band-pass filter that extracts only a signal having a frequency in the listening region, and when the rotation speed of the inner tank is low during dehydration operation, the vibration sensor detects a collision sound with the casing of the water tank, When the number of rotations of the inner tub is higher than a predetermined value, a vibration of the outer tub is detected by the vibration sensor. 2. The washing machine according to claim 1 , wherein during the dehydrating operation, the vibration is constantly monitored by the vibration sensor, and the rotation speed is controlled according to the magnitude of the vibration.

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