JP3304286B2 - Vibration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting device suitable for detecting vibration of a washing machine or the like, and more particularly to an acceleration sensor for detecting the vibration acceleration of a vibrating body including a water tub, a washing tub and the like. The present invention relates to a vibration detecting device provided.

[0002]

2. Description of the Related Art Conventional vibration detection, for example, vibration of a water tub in a washing machine, vibration of a vibrating body including a washing tub, or vibration of an outer tub caused thereby is reduced to reduce the vibration of the washing machine generated during dehydration. Many control methods for preventing occurrence of abnormal vibration or abnormal vibration have been proposed.

For example, the one disclosed in Japanese Patent Application Laid-Open No. 1-218495 has a pressure-sensitive or strain-type vibration sensor whose voltage or resistance value changes due to vibration attached to an outer tub of a washing machine, and dehydration is performed by a signal from the sensor. It is intended to control the operation and keep the vibration during dehydration within the specified range,
Japanese Unexamined Patent Publication No. 1-268597 discloses a method in which a light detector comprising a light emitting diode and a phototransistor is provided in an outer tank, and a light detector such as a reflector is provided in a vibrator, and a change in vibration is changed by a change in light. Instead, the state of vibration is detected and the same control is performed.

Japanese Patent Application Laid-Open No. 4-208199 discloses a method of detecting vibration by attaching a resonance type vibration sensor to a vibrating body.
Japanese Patent Application Publication No.-876 discloses an ON-OFF type vibration detection switch provided in an outer tub, and controls the dehydration operation based on the ON / OFF signal of the switch so that the vibration during dehydration falls within a specified range. It is to try. As a vibration acceleration sensor consisting of a piezoelectric element and a weight,
One described in 178377 is proposed.

[0005]

In the conventional apparatus having the above-described structure, the unbalanced state of the cloth is estimated from the vibration state at the initial stage of dehydration so as to suppress the vibration during dehydration. Although the operation can be controlled, if the vibration control is to be performed more accurately, or if advanced control as described in Japanese Patent Application No. 8-16357 filed by the applicant of the present invention is to be performed, the rotating drum must be controlled. It is necessary to accurately observe continuous changes in the vibration waveform of the vibrator including the vibration member.

For this purpose, it is necessary to attach a vibrometer, such as an accelerometer, to the vibrating body. The accelerometer may be a pressure-sensitive type, a strain type, or a type disclosed in Japanese Patent Application Laid-Open No. 1-218495. No. 208199, the resonance type and the like,
There are various types, but many are expensive. Also,
In order to perform continuous measurement of the vibration waveform at relatively low cost, for example, there is a method of combining inexpensive parts described in Japanese Patent Application Laid-Open No. 1-268597 to form a vibrometer. There are problems such as an error due to the deviation of the distance and a problem of a resolution caused by a change in intensity of light at a short distance.

In the acceleration sensor described in Japanese Utility Model Laid-Open No. Sho 62-178377, the weight is fixed to the surface of the piezoelectric element, and the movement of the weight is not restricted. In addition, since the fixing surface between the weight and the piezoelectric element is flat, there is a problem that the pressure detection sensitivity of the weight due to acceleration is poor.

In some cases, a projection is provided on the weight and the projection is fixed to the piezoelectric element. In this case, the piezoelectric ceramic may be damaged. If added, the weight may shift.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a vibration detection device which can detect a vibration waveform with relatively low cost and high accuracy.

[0010]

According to a first aspect of the present invention, there is provided a vibration detecting device comprising an acceleration sensor fixed to a vibrating body comprising a water tub, a washing tub, and the like. Metal diaphragm and pressure provided on one side of the metal diaphragm
A piezoelectric element formed of conductive ceramics, weight having a projection for applying a pressure corresponding to the acceleration to the piezoelectric element, constructed from the case for housing the spring, and those which restrain the piezoelectric element and the weight, the piezoelectric ceramics and A minute gap is provided between the cases facing the piezoelectric ceramic and the piezoelectric ceramic
Since the one surface of the metal diaphragm scan is provided are configured to contact the protrusion of the <br/> weight on the opposite side, increases the detection sensitivity of the vibration, also the piezoelectric ceramic by the projection portion of the weight There is no danger of injury.

Further, since the invention according to claim 2 has a configuration in which a rib is provided around a portion where the weight projection of the metal vibration plate of the piezoelectric element is in contact, it is possible to apply an adhesive or the like without applying an adhesive or the like.
The weight and the position of the piezoelectric element are securely fixed by the spring and the rib, so that the weight projection does not shift even when an excessive acceleration is applied at the time of abnormality.

According to a third aspect of the present invention, two or more spring-like electrodes are integrally formed on a base on which the piezoelectric element is fixed, and the piezoelectric element is mounted on the base by a weight and a spring for stopping the weight and the piezoelectric element. When it is fixed, it comes into contact with and conducts to the metal vibrating plate of the spring-like electrode piezoelectric element and the piezoelectric ceramic, respectively.Therefore, there is no need for a lead wire to lead the sensor output out of the sensor case. In addition, even if an excessive acceleration is applied at the time of abnormality, damage to the piezoelectric element by the electrode spring can be reduced.

Further, the invention according to claim 4 is characterized in that, even when the maximum acceleration is applied, the force of the spring-like electrode pressing the piezoelectric element is reduced by the weight and the spring which restrains the weight and the piezoelectric element. Since the piezoelectric element is configured to be smaller than the magnitude of the force applied to the element, the piezoelectric element can be securely fixed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a vibration detecting apparatus according to the present invention will be described with reference to the drawings when applied to a drum type washing machine. This vibration detecting apparatus (acceleration detecting system) is a general fully automatic apparatus. Needless to say, it can be applied to a washing machine.

FIG. 1 is a schematic configuration diagram of a drum type washing machine in which the vibration detecting device of the present invention is implemented.
Is an outer tub, and the water tub 2 is swingably suspended via a spring 3 for absorbing vibration. A vibration resistor (shock absorber) is provided between the lower part of the water tank 2 and the outer tank 1 so as to suppress steep vibration of the vibrating body including the water tank 2, the drum 5, and the like.
4 is also provided so as to be swingable, and limits vibration during dehydration.

A drum 5 is rotatably mounted inside the water tank 2 via a bearing and a shaft (not shown). The rotation of a motor 6 is transmitted from a pulley 7 to a drum pulley 9 via a belt 8 and the drum 5 rotates. A plurality of baffles (baffles) 10 are provided on the inner wall of the drum 5, and washing (tumbling washing) and rinsing are performed by lifting and dropping laundry according to the rotation of the drum 5 during washing. Usually, tumbling cleaning and rinsing are performed at a drum rotation speed of about 55 rpm, and 1000 rpm.
Dehydration is performed at a rotation speed of about pm.

Numeral 20 denotes an acceleration sensor which forms the vibration detecting device of the present invention. FIG. 1 shows an example in which the acceleration sensor is attached so as to detect vertical acceleration.

At the time of spin-drying, if the unbalance (offset) of the laundry is large, the vibration increases. Therefore, there is a method of controlling the spin-drying operation while detecting the unbalanced state by the vibration state of the vibrating body or the like at the beginning of spin-drying. And various publications such as those mentioned above. The device described in Japanese Patent Application No. Hei 8-16357 detects vibration at an early stage of dehydration and starts high-speed rotation when imbalance is minimized, which is effective in reducing vibration during dehydration. .

In order to perform these controls, it is necessary to accurately observe continuous changes in the vibration waveform of the vibrating body including the rotating drum. The present invention provides a relatively inexpensive and highly accurate vibration detecting device. Is provided.

The vibration detecting device provided by the present invention will be described mainly with reference to FIGS. 2 to 4. The acceleration sensor 20 includes a disk-shaped metal vibration plate 24 and a piezoelectric element made of a piezoelectric ceramics 25. 23 having a projection 23a for applying an excessive weight to the piezoelectric element,
3 comprises a spring 22 for restricting the movement of the case 3, a case cover 21 for accommodating them, and a case base 26.

As shown in FIG. 2, the piezoelectric element is a metal diaphragm 2
The piezoelectric ceramics 25 is provided only on one side of No. 4,
This piezoelectric element is fixedly supported on the base 26 at the circumferential portion. A weight 23 and a spring 22 are placed on the case cover 2.
The piezoelectric element 25 faces the base, and the metal diaphragm 24 is in contact with the weight projection 23a.

In order to perform advanced control in detecting drum vibration as shown in FIG. 1, it is necessary to detect minute vibration (acceleration of 0.1 or less) at a low rotation speed.
For this reason, the projection 23a is provided on the weight 23, and the distance between the piezoelectric ceramic 25 and the base 26 is increased, for example, by the allowable bending amount of the piezoelectric element, thereby increasing the detection sensitivity.

Accordingly, without damaging the surface of the piezoelectric ceramics 25 by the projections 23a of the weights 23, the piezoelectric element can be bent in accordance with the applied acceleration, and there is no fear of breakage of the piezoelectric element.

In the case shown in FIG. 3, the metal vibration plate 24 is provided with a rib 27, and the projection 23a of the weight 23 is fitted and fixed to the rib 27, thereby unexpectedly increasing the size of the product during transportation. Even if a strong impact is applied in the lateral direction, it is possible to avoid the weight 23 from shifting and coming into contact with the case cover 21, and it is also time-consuming to apply an adhesive to the weight projection 23 a and the metal diaphragm 24. Can be omitted.

Further, in the case shown in FIG. 4, a spring-like electrode 28b is integrally formed on the support portion of the metal diaphragm 24 of the base 26, and the spring-like electrode 28b is also formed so as to be in contact with the piezoelectric ceramics 25. Since the electrode 28a is integrally formed, no lead wire is required, and the influence of the vibration of the lead wire on the output can be eliminated. Further, even if the piezoelectric element is bent, the electrode contacts do not come off.

Further, the force F1 of the spring-like electrodes 28a and 28b pressing the piezoelectric element, and the force F2 applied to the piezoelectric element by the spring 22 for restraining the weight and the weight 23 always satisfy F2> F1 within the detection acceleration range. Thus, the piezoelectric element is securely fixed to the spring-like electrodes 28a and 28b, and the adverse effect on the output due to the elasticity of the electrode spring can be reduced.

FIG. 5 is a diagram illustrating an example of a change in vibration acceleration at a certain number of rotations when the vibration detection device of the present invention is used in a drum type washing machine as shown in FIG. Is accelerated so as to shift to high-speed rotation at the minimum point, the cloth can be less deviated (unbalanced) and a dehydration operation with less vibration can be performed. FIG. 6 is a block diagram showing an example of control.
Reference numeral 1 denotes an example of a control circuit of a washing machine including a microcomputer.

[0028]

Since the vibration detecting apparatus of the present invention is a structure as described above, an invention according to claim 1, a water tank, an acceleration sensor fixed to the vibrating body composed of the tub or the like, gold
Piezoelectric ceramic provided on one side of metal diaphragm and metal diaphragm
A piezoelectric element consisting of a piezoelectric element, a weight having a protrusion for applying pressure according to acceleration to the piezoelectric element, a spring for stopping the piezoelectric element and the weight, and a case for accommodating them,
Small clearance is provided between the piezoelectric ceramics and the case facing it, and, the piezoelectric ceramic is provided
Due to the one surface of the metal vibrating plate has a configuration for contacting the protrusion of the weight on the opposite side, there is no risk of damaging the piezoelectric ceramics by the detection sensitivity is good, also the protrusion of the weight of the vibration.

Further, the invention according to claim 2 has a configuration in which a rib is provided around a portion where the weight projection of the metal diaphragm of the piezoelectric element is in contact, so that it is not necessary to apply an adhesive or the like.
The position of the weight and the position of the piezoelectric element are securely fixed by the spring and the rib, so that the weight projection does not shift even when an excessive lateral acceleration is applied in the event of an abnormality.

According to a third aspect of the present invention, two or more spring-like electrodes are integrally formed on a base on which the piezoelectric element is fixed, and the piezoelectric element is mounted on the base by a weight and a spring for stopping the weight and the piezoelectric element. When fixed, the spring-shaped electrode contacts and conducts to the metal vibration plate and piezoelectric ceramic of the piezoelectric element, respectively, so lead wires that lead the sensor output out of the sensor case are unnecessary, and the output due to vibration of the lead wires is unnecessary. In addition, even if an excessive vertical acceleration is applied at the time of abnormality, damage to the piezoelectric element by the electrode spring can be reduced.

Further, according to the present invention, the magnitude of the force by which the spring-like electrode presses the piezoelectric element is increased by the weight and the spring which restrains the weight and the piezoelectric element even when the maximum acceleration is applied. Since it is configured to be smaller than the magnitude of the force applied to the element, the piezoelectric element is securely fixed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a vibration detection device according to an embodiment of the present invention when applied to a drum type washing machine.

FIG. 2 is a cross-sectional view of a main part of an acceleration sensor showing an embodiment of the vibration detection device according to the present invention.

FIG. 3 is a sectional view of a main part showing another embodiment of the acceleration sensor showing the embodiment of the vibration detection device of the present invention.

FIG. 4 is a cross-sectional view of a main part showing another embodiment of the acceleration sensor showing the embodiment of the vibration detection device of the present invention.

FIG. 5 is an explanatory diagram illustrating an example of a change in vibration acceleration according to the embodiment of the vibration detection device of the present invention.

FIG. 6 is a block diagram of a control circuit showing an embodiment of the vibration detection device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 outer tub 2 water tub 5 washing tub 6 motor 11 control circuit 20 acceleration sensor 21 sensor case 22 spring 23 weight 23a weight protrusion 24 metal diaphragm 25 piezoelectric ceramics 26 sensor case (base) 27 rib 28a spring-like electrode a 28b spring Electrode b 29 fixed spring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01H 11/08 D06F 33/02 G01P 15/09

Claims (4)

(57) [Claims] 1. A vibration detecting device for fixing an acceleration sensor configured such that a piezoelectric element is bent by an applied acceleration to a vibrating body including a water tub, a washing tub, and the like, and detecting a vibration waveform of the vibrating body. The sensor is a metal diaphragm and a piece of the metal diaphragm.
A piezoelectric element comprising a piezoelectric ceramic provided on the surface, the weight having a projection for applying a pressure corresponding to the acceleration to the piezoelectric element, is composed of a case housing the spring, and those which restrain the piezoelectric element and the weight, the small clearance is provided between the piezoelectric ceramics and the case facing it, and, the
It is opposite to one side of the metal diaphragm provided with piezoelectric ceramics.
Vibration detecting apparatus being characterized in that the structure for contacting the protrusion of the weight on the surface of the contralateral. 2. The piezoelectric element according to claim 1, wherein a rib is provided around a portion where the weight projection of the metal vibration plate contacts, and the position of the weight and the piezoelectric element is fixed by the rib. Vibration detection device. In the acceleration sensor, two or more spring-like electrodes are integrally formed on a base for fixing the piezoelectric element, and the piezoelectric element is fixed to the base by a weight and a spring for stopping the weight and the piezoelectric element. 2. The vibration detection device according to claim 1, wherein the sensor output is led out of the sensor case when the spring-like electrode contacts and conducts with the metal vibration plate and the piezoelectric ceramic of the piezoelectric element, respectively. 4. The magnitude of the force by which the spring-like electrode presses the piezoelectric element is smaller than the magnitude of the force applied to the piezoelectric element by the weight and the spring that restrains the weight and the piezoelectric element even when the maximum acceleration is applied. The vibration detecting device according to claim 3, wherein: