JP2002200392A - Vibration control device for washing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of such a trouble that an outer tub hits an outer frame or the like even when the deviation of clothing occurs during a spin-drying process in a washing machine and to reduce the vibration of the outer frame and the noise caused by it. SOLUTION: This vibration control device is provided with a support rod 2 supporting a washing/spin-drying tub and the outer tub from above a main body, a sliding tube 12 into which the support rod penetrates, a slider 13 disposed at the lower end of the support rod and vertically vibrated in contact with the inner periphery of the sliding tube via a vibration control spring 11, a vibration control tube 14 kept in contact with the outer periphery of the vibration control spring, and a ring spring 15 added on the lower section inner periphery of the slider. The slider is provided with air holes 16a and 16b penetrating into the sliding tube. A damping ratio is increased to increase frictional damping until the revolving speed of the washing/spin-drying tub passes a resonance point, and the damping ratio is reduced to reduce air damping after the revolving speed passes the resonance point. As the ratio of damping elements at resonance, the sum of both frictional and viscous damping ratios is set to 8 or above against the air damping ratio of less than 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolator for supporting an outer tub of a washing machine from above an outer frame.

[0002]

2. Description of the Related Art Conventionally, an anti-vibration device in a washing machine is provided with an anti-vibration spring and a damping mechanism on a support rod supported by an outer frame, and suspends an outer tub. The structure of the damping mechanism is mainly composed of a sliding cylinder that penetrates the support rod and a slider bumi that is in contact with the inner circumference of the sliding cylinder and is arranged at the lower end of the support rod. An anti-vibration spring exists between the sliders. The factors of damping by the conventional vibration isolator are the friction damping caused by the contact friction between the inner circumference of the sliding cylinder and the slider, the viscous attenuation by grease adhering to the slider, and the sliding cylinder and the sliding cylinder. There is air decay that occurs in the space of the moving element Bukumi, and a smooth dewatering process is performed by these three types of decay effects.

[0003] However, when the clothes contained in the washing and dewatering tub are in an unbalanced state at the start of the dehydration, the outer tub vibrates greatly even with these vibration damping devices.
In particular, a resonance phenomenon occurs in which the outer tub vibrates greatly in the vertical direction when the rotation frequency of the washing and dewatering tub coincides with the natural frequency of the object, that is, when the so-called resonance frequency is passed. Happens.

In order to solve the problem caused by the resonance phenomenon,
It is necessary to increase the damping force of the damping mechanism. Considering the one-degree-of-freedom vibration system, the amplitude of the vibration isolator χ and the amplitude of the outer tank χ
_The vibration transmissibility τ calculated from ₀ is

[0005]

(Equation 1) From the equation (1), the characteristics of the vibration transmission rate τ according to the rotation frequency ω of the washing and dewatering tub and the damping ratio を indicating the magnitude of the damping force are shown in FIG. A characteristic line 27 shows characteristics when the attenuation ratio 小 さ い is small, and a characteristic line 28 shows characteristics when the attenuation ratio 大 き い is large.

[0006] In order to reduce the occurrence of defects due to the resonance phenomenon, it is required that the vibration transmissibility τ at the resonance frequency 29 be small, and therefore, a characteristic line 28 having a large damping ratio ζ is preferred. However, when the rotation frequency ω of the washing and dewatering tub is high, the vibration of the outer frame is required to be small.
The characteristic line 2 where the attenuation ratio 小 さ い is small at the steady frequency of 30
7 is good. That is, the attenuation ratio ζ is ideally large when the rotation frequency ω of the washing and dewatering tub is near the resonance frequency of the vibration system, and is small after passing through the resonance frequency of the vibration system.

Also, the elements of the spring mechanism of the conventional vibration isolator are generated by the vibration isolating spring between the inside of the sliding cylinder and the slider bukumi in the damping mechanism and the air pressure between the sliding cylinder and the slider bumi. The air spring which is present exists as a large element. In particular, as the rotation frequency ω of the washing and dewatering tub increases, the spring constant of the air spring increases as indicated by a characteristic line 31 in FIG. For this reason, the spring constant of the whole vibration isolator increases, and a damping phenomenon occurs in a state where the rotation frequency ω of the washing and dewatering tub is high, and the vibration of the outer frame increases.

As a method for solving the above-mentioned problems, a spin-drying process is judged in real time by a method such as detecting the number of revolutions of a washing and spin-drying tub or the rotation speed of a drive motor or the vibration of the main body of a washing machine, and an electromagnet, etc. There is a case in which the above problem is solved by performing variable control of the damping force by adding a motor, or controlling opening and closing of an air chamber by adding a drive motor or the like.

[0009]

In such a vibration isolator, the rotation frequency of the washing and dewatering tub is detected, and it is easy to determine whether or not the dehydration process is in a resonance phenomenon. Since the vibration isolator always vibrates vertically and horizontally during the stroke, it is difficult to transmit an operation signal and a rotation frequency detection signal to an electromagnet or the like for variably controlling the damping force. Similarly, it is difficult to transmit the operation signal and the detection signal for the opening / closing control of the air chamber, and the means for opening / closing is not easy. In addition, there are many additional parts, and when dehydration starts, if the phenomenon that the outer tub hits the outer frame due to the unbalanced state of the clothes contained in the washing and dewatering tub occurs, trouble such as breakdown occurs Might be.

An object of the present invention is to simplify the structure and to perform the entire operation until the rotation frequency of the washing and dewatering tub passes the resonance frequency point without performing electrical control such as detection of the rotation frequency. By increasing the damping ratio ζ to reduce the occurrence of defects due to the resonance phenomenon, and further reducing the overall damping ratio 通過 after passing the resonance frequency point, and reducing the occurrence of air springs due to air pressure, Another object of the present invention is to provide an anti-vibration device for a washing machine in which noise associated therewith is reduced.

[0011]

In order to achieve the above-mentioned object, a first aspect of the present invention provides a support rod for supporting a washing and dewatering tub and an outer tub for storing water from an upper portion of a main body, and a slide penetrating the support rod. In a vibration isolator having a moving cylinder and a slider that vibrates up and down in contact with the inner periphery of the sliding cylinder via a vibration isolating spring at the lower end of the support rod, a vibration isolating tube that contacts the outer periphery of the vibration isolating spring. A ring spring attached to the lower inner periphery of the slider to contact the inner surface of the sliding cylinder with an elastic force. The slider has air passing through the sliding cylinder. It is characterized in that a hole is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the frictional force generated between the vibration isolating spring and the vibration isolating tube, and the frictional force generated between the sliding cylinder having the ring spring and the slider. It is characterized by using frictional force as a damping effect.

According to a third aspect of the present invention, in the first aspect of the present invention, the area of the air hole provided in the slider is such that when the rotation speed of the washing and dewatering tub is high, the damping effect by air is substantially negligible. It is characterized by having a large size.

According to a fourth aspect of the present invention, in the first aspect of the invention, grease is provided between the slider and the sliding cylinder.

According to a fifth aspect of the present invention, in the first aspect of the present invention, when the rotation frequency of the washing and dewatering tub is equal to the natural frequency of the vibration system, the frictional force, the viscosity, and the air The ratio of the damping ratio is characterized in that the sum of the friction damping ratio and the viscous damping ratio is 8 or more with respect to the air damping ratio of less than 2.

[0016]

[Function] Considering a vibration system in which a dry friction force acts sufficiently, the equation of motion by the vibration system is generally

(Equation 2) And the natural frequency ω _n of the vibration system is

(Equation 3) The damping ratio ζ is

(Equation 4) It is represented by Expanding the equations (2), (3) and (4), the relationship between the damping coefficient c and the damping ratio ζ is

(Equation 5) Holds.

Next, the equation of motion of the vibrating system in which the dry friction force is sufficiently acting is:

(Equation 6) It is represented by In this case, the magnitude of the damping force due to the dry frictional force F _C is constant, but the direction changes depending on the direction of the speed due to the equivalent exciting force of the outer tank. The equivalent viscous damping the dry friction force F _C, i.e. to consider replacing the equivalent viscous damping coefficient C _e. The method, the energy dissipated during 1 cycle of vibration due to dry friction obtaining an equivalent viscous damping coefficient C _e and equal to that due to viscous damping.

[0018] The dissipated energy in one cycle is 4χ ₀ F _C, the relationship between the equivalent attenuation at this time and dissipated energy,

(Equation 7) Becomes Thus, dry friction force F _C equivalent equivalent viscous damping coefficient C _e is

(Equation 8) Becomes

The relationship with the damping ratio ζ when there is a dry frictional force F _C is obtained from equations (5) and (8).

(Equation 9) Holds. Damping ratio of vibration system with dry friction force F _C ζ
Varies according to the rotation frequency ω of the washing and dewatering tub, and the equation (1)
From equation (9), the relationship between the rotation frequency ω of the washing and dewatering tub where the dry frictional force F _C exists and the vibration transmissibility τ is shown by the characteristic line 3 in FIG.
It becomes 2.

Further, in order to reduce the obstacle caused by the air spring when the rotation frequency ω of the washing and dewatering tub is high, the damping effect by air is reduced as much as possible, and the rise of the spring constant of the whole vibration isolator is suppressed. In a state where the rotational frequency ω is high, there is no damping phenomenon.

As described above, in order to reduce the damping force due to air, the present invention provides a passage through the sliding cylinder to the sliding cylinder so that the air from the sliding cylinder and the slider can efficiently flow in and out of the outside. In order to use frictional and viscous forces for the majority of the damping effect provided, a vibration isolating tube is added to the outer periphery of the vibration isolating spring, and a ring spring is added to the inner periphery of the lower part of the slider bukumi to reduce friction and viscous damping. increase. At this time, the sum of the damping ratios of friction and viscosity is set to 8 or more while the ratio of the damping element at resonance is less than the air damping ratio of 2.

With such a configuration, the attenuation ratio is large until the rotation speed of the washing and dewatering tub passes through the resonance point. Therefore, even if the dehydration process is performed in an unbalanced state due to the bias of the clothes, the outer tub due to the resonance phenomenon occurs. , And the attenuation ratio is small after passing through the resonance point, so that the vibration of the main body and the accompanying noise can be reduced.

[0023]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a fully automatic washing machine as one embodiment of a washing machine to which the vibration damping device of the present invention is applied. The washing machine has a structure in which a synthetic resin outer tub 4 for storing water for washing is suspended by four support rods 2 and a vibration isolator 3 arranged in an outer frame 1 made of a steel plate. I have.

In the outer tub 4, a washing and dewatering tub 5 made of synthetic resin is rotatably disposed, and a stirring blade 6 made of a pulsator or an agitator is provided at the center bottom of the washing and dehydration tub 5. It is provided rotatably. During the washing operation and the rinsing operation, the washing / dewatering tub 5 is stopped and the stirring blade 6 is stopped.
Is rotated clockwise and counterclockwise. At the time of spin-drying, the washing and spin-drying tub 5 is rotated in one direction. A top cover 7 made of a synthetic resin is provided on the upper part of the outer frame 1, and a lid 8 made of a synthetic resin is attached to the top cover 7.

FIG. 2 is a sectional view of the vibration isolator of the present invention.
The anti-vibration device 3 penetrates both the slider 13 and the anti-vibration spring 11 around the support rod 2 at the lower end of the support rod 2, and further surrounds the slider 13 and the anti-vibration spring 11 around the support rod 2. Sliding cylinder 12
Is provided. The slider 13 is brought into contact with the inner peripheral portion of the sliding cylinder 12 to obtain frictional resistance when a resonance phenomenon occurs. A rubber or soft vinyl chloride vibration isolating tube 14 is provided on the outer periphery of the vibration isolating spring 11 so as to obtain a frictional resistance when the vibration isolating spring 11 oscillates vertically when a resonance phenomenon occurs. It has become.

FIG. 3 is a front view of the ring spring 15, and FIG. 4 is a side view. The ring spring 15 is made of a circular steel wire,
It is added to the lower inner periphery of the slider 13. Before the ring spring 15 is incorporated into the vibration isolator 3, the outer diameter of the ring spring 15 is made larger than the inner diameter of the lower part of the slider 13 where the slit 17 is formed. In the lower part of the slider 13, a plurality of slits 17, in order to obtain a greater spring force of the ring spring 15 and to obtain the spring force evenly over the entire circumference,
For example, six are provided, and the slider 13 is brought into contact with the inner peripheral surface of the sliding cylinder 12 by the spring force of the ring spring 15. As shown in FIG. 5, a pawl 17a is provided at the center of each slit 17 at the bottom of the slider 13 in order to eliminate the displacement of the ring spring 15 due to the vertical movement of the slider 13. As shown in FIG. Thus, the displacement between the slider 13 and the ring spring 15 is regulated, and the frictional force can be obtained uniformly.

When incorporated in the vibration isolator 3, the outer diameter of the slit 17 of the slider 13 increases due to the spring force of the ring spring 15, and the lower part of the slider 13 is widened. Many frictional forces can be obtained in between. Further, air holes 16a through which air in a space formed between the slider 13 and the sliding cylinder 12 easily flows in and out of the slider 13 are provided.
16b is provided.

The sliding cylinder 12 is made of high-sliding polyethylene, thereby preventing friction with the slider 13 and deformation of the outer tub 4 due to vibration. On the other hand, the sliding element 13 is prevented from being worn by contact friction with the sliding cylinder 12 by using polybutylene terephthalate. The viscous force between the contact portion of the slider 13 and the sliding cylinder 12 is obtained,
In order to prevent deformation of the sliding cylinder 12 due to friction and the like, grease 18 having a viscous effect is attached to both members.

FIG. 6 shows an example of the change characteristics of the rotation speed and the damping ratio の of the washing and dewatering tub 5 by the vibration isolator 3 of the present invention. In the change characteristic line 20, the damping ratio 22 at the resonance speed 21 is large, but the damping ratio 後 after passing through the resonance speed 22 gradually decreases, and the damping ratio 24 at the steady speed 23 decreases. . The value of the damping ratio に お け る in the change characteristic line 20 is such that the damping ratio 22 of the resonance speed 21 is equal to 0.1.
56, the damping ratio 24 of the steady speed 23 is 0.14.

FIG. 7 is an enlarged view of the vicinity of the slider 13 in the vibration isolator 3 of the present invention. The names and numbers of the parts are the same as in FIG. Slider 13
Air holes 16a and 16b need an effect as air damping at the time of passage of the resonance rotation speed 21, and the steady rotation speed 23
At this time, a size is required to reduce the effect of the air spring. Further, two support rods 2 are arranged to face each other in order to allow the air contained in the sliding cylinder 12 and the slider 13 to flow out evenly.

FIG. 8 shows the change characteristics of the opening area and the damping ratio の of the air holes 16a and 16b for letting the air out of the slider 13 and the sliding cylinder 12 depending on the resonance speed and the steady speed. This is an example. The relationship between the opening area and the damping ratio に お け る at the resonance rotation speed 21 was determined at resonance rotation 25 and steady rotation speed 2.
3 at the time of steady rotation.
And Although the damping ratio の at the time of resonance rotation 25 gradually decreases as the opening area increases, the characteristic is such that the opening area S3 sharply decreases to Sakai. The damping ratio の at the time of steady rotation 26 sharply decreases as the opening area increases, but the characteristic is such that the opening area S1 is reduced to a smaller value and the change in the decrease is reduced.

From the above, when the rotation speed of the washing and dewatering tub 5 is the resonance rotation speed 21, the effect as the air damping is maintained, and when the rotation speed is the steady rotation speed 23, the damping effect is reduced.
In order to reduce the trouble caused by the air spring, the opening areas of the air holes 16a and 16b of the slider 13 are set between S1 and S3. The size of the air hole of the present invention is φ2, and the total area of the ^two openings is 6.28 mm ² .

[0033]

According to the present invention, the amplitude of the outer tub due to the resonance phenomenon can be suppressed even when the spin-drying process is performed with the clothes in the washing and dewatering tub offset. Problems such as hitting the cover can be reduced.
Furthermore, since the outer tub vibration during steady rotation is not transmitted to the support rod, the vibration of the main body and the noise generated thereby can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fully automatic washing machine showing one embodiment of the present invention.

FIG. 2 is a sectional view of the vibration isolator of the present invention.

FIG. 3 is a front view of the ring spring.

FIG. 4 is a side view of the ring spring.

FIG. 5 is a bottom view of the vibration isolator of the present invention.

FIG. 6 is a change characteristic diagram of an attenuation ratio showing one embodiment of the vibration isolator of the present invention.

FIG. 7 is an enlarged view around a slider according to the present invention.

FIG. 8 is a change characteristic diagram of an air inflow / outflow area and a damping ratio.

FIG. 9 is a characteristic diagram of a vibration transmission rate and a damping ratio depending on a rotation frequency.

FIG. 10 is a characteristic diagram of a rotation frequency and an air spring constant.

FIG. 11 is a change characteristic diagram of an equivalent damping ratio between a vibration transmissibility and dry friction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer frame, 3 ... Anti-vibration device, 4 ... Outer tank, 11 ... Anti-vibration spring,
12 ... sliding cylinder, 13 ... sliding Doko, 14 ... anti fucan, 15 ... wheel spring, 16a, 16b ... air holes

Continued on the front page (72) Inventor Tamotsu Kamori 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Electrification Equipment Division, Hitachi, Ltd. No. 1 Hitachi, Ltd. Electrical Equipment Division (72) Inventor Shunichi Ishikawa 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture DD01 GC02 GC03 MA02 MA05 3J048 AA03 BE02 BE06 BE12 DA04 EA07

Claims (5)

[Claims] A supporting rod for supporting a washing and dewatering tub and an outer tub for storing water from an upper portion of the main body; a sliding cylinder penetrating the supporting rod; and a sliding cylinder at a lower end of the supporting rod via a vibration-proof spring. An anti-vibration device having a slider that comes into contact with the inner periphery of a moving cylinder and vibrates up and down, comprising: a vibration isolating tube that contacts an outer periphery of the vibration isolating spring; A ring spring for bringing the moving element into contact with the inner peripheral surface of the sliding cylinder with an elastic force, wherein the sliding element is provided with an air hole penetrating into the sliding cylinder. And the anti-vibration device of the washing machine. 2. A friction force generated between the vibration isolating spring and the vibration isolating tube, and a frictional force generated between the sliding cylinder to which the ring spring is added and the slider, according to claim 1. A vibration isolator for a washing machine, wherein frictional force is used as a damping effect. 3. The air hole provided in the slider according to claim 1, wherein the area of the air hole is such that when the rotation speed of the washing and dewatering tub is high, the damping effect by air is substantially negligible. A vibration isolator for a washing machine, characterized in that: 4. A vibration isolator for a washing machine according to claim 1, wherein grease is provided between said slider and said sliding cylinder. 5. The ratio of the respective damping ratios of friction force, viscosity and air when the rotation frequency of the washing and dewatering tub is equal to the natural frequency of the vibration system, according to any one of claims 1 to 4. The sum of the frictional damping ratio and the viscous damping ratio becomes 8 or more with respect to the air damping ratio of less than 2.