KR20020060083A - Vibration isolator for washing machine - Google Patents

Abstract

PURPOSE: 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. CONSTITUTION: 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

Vibration isolator for washing machine {VIBRATION ISOLATOR FOR WASHING MACHINE}

The present invention relates to a vibration isolation device for a washing machine for supporting an outer cylinder on an outer frame.

Conventional washing machines have an outer frame provided with a vibration isolation spring and a damping system and holding a support bar for suspending the outer cylinder. The damping system mainly comprises a slide cylinder through which the support bar penetrates, a slide subassembly in contact with the inner surface of the slide cylinder and provided at the bottom of the support bar, and vibration isolation between the inner surface of the slide cylinder and the slide cycle subassembly. It includes a spring. Conventional insulation devices have three damping elements: friction damping caused by contact friction between the inner surface of the slide cylinder and the slide cycle subassembly, viscous damping caused by grease stuck on the slide cycle subassembly, and slide Air damping occurs inside the space between the cylinder and the slide cycle subassembly. These three damping effects enable smooth dehydration rotation.

However, during the start of rotary dehydration, if the bundle of garments in the wash and dewatering can cause an imbalance, this vibration isolation device cannot stop the vibration of the outer cylinder. In particular, when the rotational frequency of the washing and dewatering container passes through the natural frequency of the object, that is, the same frequency as the resonant frequency, a resonance phenomenon occurs in which the outer cylinder vibrates in the vertical direction and the outer cylinder hits the main body. do.

In order to solve this problem of resonance, an attenuation system having a high degree of damping force is required. Given a vibration system of 1 degree of freedom, the vibration transmission rate τ is derived from the amplitude X of the vibration isolator and the amplitude X ₀ of the outer cylinder as follows.

(τ: vibration transmission rate, X: relative amplitude between the slide cylinder and the slide cycle subassembly, X ₀ : amplitude of the cylinder, ζ: damping ratio, ω: rotational frequency of the washing and dewatering container)

From Equation 1, Fig. 9 shows a characteristic curve of the vibration transmission rate τ versus the rotation frequency ω of the washing-and-dehydrating tub with a change in the damping ratio ζ representing the degree of damping force. The characteristic curve 27 is for the low damping ratio ζ and the curve 28 is for the high damping ratio ζ.

In order to reduce the problems caused by the resonance phenomenon, a smaller vibration transmission rate? Is required at the resonance rotational frequency 29. Therefore, the characteristic curve 28 for the high damping ratio ζ is preferable at the resonance frequency 29. On the other hand, at the high rotational frequency ω of the washing and dewatering container, smaller vibration of the outer frame is required. Therefore, the characteristic curve 27 for the low damping ratio ζ at the stationary frequency 30 is preferable. That is, the ideal damping ratio ζ is higher when the rotational frequency ω of the washing and dewatering container is near the resonance rotational frequency 29 of the vibration system, and the rotational frequency ω is higher than the resonance frequency 29 of the vibration system. The time has to change in a lower way. In a conventional vibration isolator, the spring mechanism comprises two main elements of the damping system, one is a vibration isolation spring between the inner surface of the slide cylinder and the slide cycle subassembly, and the other is a slide cylinder and slide cycle element. It is an air spring caused by air pressure between the assemblies. In particular, the air spring has a spring constant that increases with an increase in the rotational frequency ω of the washing and dewatering container as shown by the characteristic curve 31 shown in FIG. This increases the spring constant of the entire vibration isolator, causing attenuation at higher rotational frequencies of the wash and spinneret and increasing external frame vibrations.

In order to solve the above problems, some solutions to the vibration isolation device have been proposed. For example, the detection of the rotation frequency of the washing and dehydrating container or the driving motor or the detection of the vibration of the washing machine main body for real-time determination of the rotation dehydration operation, the addition of an electromagnet on the vibration isolator for the variable control of the damping force, and the opening and closing of the air chamber. There is an additional drive motor for control.

In such a vibration isolator, it is easy to detect the rotation frequency of the washing-and-dehydration pail to determine whether a resonance phenomenon occurs during the rotation dehydration operation. However, since the vibration isolation device always vibrates vertically and horizontally during the rotational dehydration operation, it is difficult to transmit the operation signal and the detected signal of the rotation frequency to the electromagnet or the like for the variable control of the damping force. In the opening and closing control of the air chamber, it is also difficult to transmit the operation signal and the detected signal to the drive motor. In addition, it is difficult to realize a means capable of opening and closing the air chamber. In both cases, many additional parts are also required, during the start of the spin dewatering, if the bundle of clothes in the wash and spinneret is out of center and unbalanced causes the outer bin to hit the outer frame, such as a malfunction. Some problems may arise.

Therefore, it is an object of the present invention to have a simple structure and to reduce the problems caused by the resonance phenomenon at rotational frequencies above the resonance frequency with a higher total damping ratio at the rotational frequency of the washing and dewatering vessel not exceeding the resonance rotational frequency. It does not require any electrical control, such as detection of rotational frequency to have a lower total damping ratio, and provides a vibration isolation device for a washing machine which reduces the generation of air springs caused by air pressure, thereby reducing vibration of the body and the resulting noise. It is.

1 is a cross-sectional view showing an example of a fully automatic washing machine according to the present invention.

2 is a sectional view showing a vibration isolation device according to the present invention.

Figure 3 is a front view showing a ring spring according to the present invention.

Figure 4 is a side view showing a ring spring according to the present invention.

Figure 5 is a bottom view of the vibration isolating device according to the present invention.

6 is a view showing an example of the characteristics of the damping ratio change of the vibration isolation device according to the present invention.

Figure 7 is an enlarged view showing the slide and its periphery in accordance with the present invention.

Figure 8 is a view showing the characteristics of the change in the damping ratio versus the area in which air is introduced / discharged in accordance with the present invention.

9 is a view showing the characteristics of the rotation frequency according to the change of the vibration transmission rate to the damping ratio according to the present invention.

10 shows the characteristics of spring constant versus rotational frequency in accordance with the present invention;

Fig. 11 shows the characteristics of the rotational frequency with respect to the change in the equivalent damping ratio of the vibration transmission rate to the dehydration friction force.

<Explanation of symbols for the main parts of the drawings>

1: frame

2: bar

3: insulation device

4: outer downlight

5: washing and dehydration

11: Spring

12: slide cylinder

13: life cycle

14: Vibration Insulation Tube

15: ring spring

17: Slit

17a: lug part

In order to solve the above-mentioned problem, the invention of claim 1 further includes a support bar suspended from the top of a main body, a laundry dehydration bucket and an outer cylinder for receiving water, a slide cylinder through which the support bar passes, and the slide A vibration isolating device for a washing machine, which is in contact with an inner surface of a cylinder and which can vibrate vertically and includes a slide provided at a lower end of the support bar via a vibration insulating spring, wherein the vibration isolating device is a vibration insulating device. And an oscillating insulation tube provided on an outer periphery, and a ring spring provided on the bottom inner surface of the slide cycle, the slide cycle being in elastic contact with the inner surface of the slide cylinder, the slide cycle being adapted to the slide cycle. Air holes penetrating into the slide cylinder.

The invention according to claim 2 is the invention according to claim 1, wherein the friction force generated between the vibration insulation spring and the vibration insulation tube and the friction force generated between the slide cylinder with the ring spring and the slide period are damped. Used as an effect.

The invention of claim 3 is the invention according to claim 1, wherein the air hole on the slide has an area suitable for almost eliminating the air damping effect at higher rotational frequencies of the wash and dewatering can.

The invention of claim 4 is the invention according to claim 1, wherein grease is provided between the slide period and the slide cylinder.

The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the ratio between friction, viscosity and air damping ratio is equal to the rotational frequency of the washing and dehydrating pail equal to the natural frequency of the vibration system. The air damping ratio is less than 2 and the sum of the frictional and viscous damping ratios is 8 or more.

Vibration systems with sufficient dehydration friction will be considered. First, the equation of motion for the whole vibration system is described in equation 2 below.

Where P ₀ is the equivalent vibration force on the outer cylinder subassembly, X is the relative amplitude between the slide cylinder and the slide cycle subassembly, = Relative velocity between the slide cylinder and the slide cycle subassembly, : Relative acceleration between the slide cylinder and the slide cycle component, m: mass of the outer cylinder subassembly, c: damping component, k: spring constant)

The natural frequency ω _n is described in Equation 3 below.

The damping ratio ζ is described in Equation 4 below.

Equations 2, 3 and 4 are developed and the relationship between the damping constant c and the damping ratio ζ can be described in Equation 5 below.

Next, the equation of motion for a vibration system with sufficient dehydration frictional force is described in equation (6) below.

(Where F _c : dehydration friction)

In Equation 6, the dehydration friction force F _c causes a certain amount of damping force. However, the direction of the damping force depends on the direction of the equivalent vibration force P ₀ of the outer cylinder. Dehydration friction (Fc) may be replaced by its equivalent viscous damping, i.e., equivalent viscous damping coefficient (C _e). The equivalent viscous damping coefficient C _e can be obtained by the assumption that the energy dissipated by the dehydrating frictional force during one period of vibration is equal to the energy dissipated by the viscous damping.

The energy dissipated by dehydration friction during one cycle is 4X ₀ F _c . Therefore, the relation between the dissipated energy and the equivalent attenuation is described in Equation 7 below.

Therefore, from Equation 7 above, an equivalent viscous damping coefficient Ce equal to the dehydration friction force F _c can be obtained as in Equation 8 below.

Along with the dehydration friction force F _c , the damping ratio ζ can be described from Eqs. 5 and 8 as in Equation 9 below.

Therefore, in the vibration system with the dehydration friction force F _c , the damping ratio ζ is largely dependent on the rotational frequency ω of the washing and dewatering tub. From Equations 1 and 9, Fig. 11 shows a characteristic curve 32 for the relationship between the vibration transmission rate? And the rotational frequency of the washing and dehydrating tub in the presence of the dehydration friction force Fc.

In addition, the damping effect caused by the air is reduced as much as possible in order to reduce the problem from the air spring at the higher rotational frequency τ of the washing and dewatering can. That is, the spring constant of the entire vibration isolator is suppressed from increasing so that the damping phenomenon can be eliminated at the higher rotational frequency τ of the washing and dewatering container.

According to the present invention, in the slide cycle subassembly, air damping force is reduced by providing passages passing through the subassembly into the slide cylinder so that air can effectively flow between the outside and the slide cylinder and the space in the slide cycle subassembly. Can be. In addition, in order to create most damping effects by friction and viscous forces, vibration isolation tubes are provided on the outer periphery of the vibration isolation spring and ring springs are provided on the lower inner surface of the slide subassembly to increase friction and viscosity. have. Thus, the ratio between the damping elements in the resonant frequency is such that the air damping ratio is less than two and the sum of the frictional and viscous damping ratios is greater than or equal to eight.

In such a configuration, a higher damping ratio can be obtained with respect to the rotational frequency of the washing and dewatering bottle not exceeding the resonance point. It is therefore possible to reduce the vertical amplitude of the outer cylinder caused by the resonance phenomenon during the rotary dehydration operation under the unbalanced state where the bundle of clothes is off center.

Lower damping ratios can also be obtained for rotational frequencies above the resonance point of the cylinder, making it possible to reduce vibrations of the body and the resulting noise.

An example of the present invention will be described below with reference to the accompanying Figure 1, which shows a cross-sectional view of a fully automatic washing machine as an example of a washing machine to which the vibration isolation device according to the present invention is applied. The washing machine has a steel plate outer frame 1 on which four support bars 2 and a vibration isolation device 3 are arranged. The bar 2 and the insulation device 3 suspend an outer barrel 4 made of synthetic resin for retaining wash water.

The washing and dewatering container 5 made of synthetic resin is rotatably disposed inside the outer cylinder 4. A stirring blade 6, such as a pulsator or an agitator, is rotatably disposed in the center of the bottom of the wash and dewatering container 5. During the washing or rinsing operation, the washing and dewatering container 5 is stopped and the stirring blade 6 is rotated clockwise or counterclockwise. During the rotary dewatering operation, the washing and dewatering container 5 is rotated in one direction. On top of the outer cylinder 1 is a synthetic resin top cover 7 having a synthetic resin lid 8.

Figure 2 shows a cross-sectional view of a vibration isolation device according to the present invention. The vibration isolation device 3 has a slide 13 provided at the lower end of the support bar 2 and a vibration isolation spring 11 provided around the bar 2 in the center of the spring 11. Both the slide 13 and the spring 11 pass through the vibration isolation device 3. A slide cylinder 12 is disposed around the bar 2 set in the center in the cylinder 12 and surrounds the slide cycle 13 and the vibration isolation spring 11. The slide cycle 13 is in contact with the inner surface of the slide cylinder 12 so that frictional resistance can occur during resonance. The outer periphery of the vibration isolation spring 11 has a vibration insulation tube made of rubber or non-rigid polyvinyl chloride such that friction resistance against vertical vibration of the vibration isolation spring 11 occurs during resonance. 14 is provided.

3 and 4 respectively show a front view and a side view of a ring spring 15 according to the invention. The ring spring 15 is made of circular steel wire and is added on the lower inner surface of the slide period 13. The outer diameter of the ring spring 15 is larger than the inner diameter below the slide period 13 provided with the slit 17 before being incorporated into the vibration isolation device 3. The lower part of the slide 13 has a plurality of slits 17, such as six slits, to strengthen the spring force of the ring spring 15 and to make the force uniform along the entire inner diameter. The spring force of the ring spring 15 causes the slide cycle 13 to be in contact with the inner surface of the slide cylinder 12. As shown in Fig. 5, at the bottom of the slide period 13, each slit 17 has a lug at its center to prevent the ring spring 15 from slipping out during the vertical movement of the slide period 13. lug; 17a). This lug 17a can limit the displacement between the slide 13 and the ring spring 15 so that a uniform frictional force can be obtained.

The ring spring 15 incorporated in the vibration isolation device 3 can generate a spring force that can enlarge the outer diameter of the slit 17 and thereby enlarge the lower part of the slide 13. Thus, a large friction force can be obtained between the slide cylinder 12 and the slit 17. The slide cycle 13 is also provided with air holes 16a and 16b through which the air in the space defined by the slide cycle 13 and the slide cylinder 12 can be easily introduced / outflowed.

The slide cylinder 12 is preferably made of polyethylene with high sliding performance to prevent deformation due to friction with the slide cycle 13 and vibration of the outer cylinder 4. The slide cycle 13 is preferably made of polybutylene terephthalate to prevent wear due to contact friction with the slide cylinder 12. Viscous grease 18 is provided between the slide period 13 and the slide cylinder 12 to obtain a viscous force at the contact portion between both members, to prevent deformation due to friction between the two members, and the like.

FIG. 6 shows an example of the change characteristic of the damping ratio ζ to the rotational frequency of the washing and dewatering container 5 for the vibration isolating device 3 according to the present invention. The change characteristic curve 20 has a higher damping ratio 22 at the resonance frequency 21, a damping ratio ζ gradually decreasing beyond the resonance frequency 21, and a lower damping ratio 24 at the normal frequency 23. Shows. The values of the damping ratio ζ in the change characteristic curve 20 are 0.56 at the resonance frequency 21 and 0.14 at the normal frequency 23.

7 shows an enlarged view of the slide 13 and its periphery of the vibration isolating device 3 according to the invention. Since each element in FIG. 7 uses the same name and reference numerals as in FIG. 2, description of each element is omitted. The air holes 16a and 16b of the slide period 13 should act as air attenuation when the frequency passes the resonant frequency 21. The holes 16a and 16b should also have an area sufficient to reduce the air spring effect at the normal frequency 23. The four support bars 2 have two pairs of opposing bars 2 to evenly flow air into the cylinder 12 and the slide period 13.

Fig. 8 shows an example of a change characteristic of the opening area of the air holes 16a and 16b through which air flows in and out of the slide cycle 13 and the slide cylinder 12 at the damping ratio ζ vs. the resonance frequency and the normal frequency. Shows. The relationship between the opening area and the damping ratio ζ at the resonance frequency 21 represents the curve 21 at the resonance frequency. The relationship between the aperture area and the damping ratio ζ at the stationary frequency 21 represents the curve 25 at the resonance frequency. The damping ratio ζ of the curve 25 gradually decreases as the opening area increases, and then rapidly decreases when the opening area S3 is exceeded. The damping ratio ζ of the curve 26 decreases rapidly as the opening area increases, but decreases at a smaller rate when the opening area S1 is exceeded.

Therefore, the opening areas of the air holes 16a and 16b of the slide period 13 are preferably set between S1 and S2. This maintains the air damping effect with the holes 16a and 16b together with the frequency of the washing and dewatering container 5 at the resonant frequency 21, and reduces the damping effect and problems of the air spring effect at the normal frequency 23. To make it possible. Each air hole of the present invention has an area of Φ ^{2 and} the total opening area of the two holes is 6.28 mm ² .

According to the present invention, even when the dewatering rotation operation is performed in a state in which the clothes are bundled together in the washing and dewatering container, it prevents vibration of the outer cylinder due to the resonance phenomenon and reduces the problem that the outer cylinder hits the outer frame or the top cover. It is possible to let. In addition, since the vibration of the outer cylinder during the normal rotation is not transmitted to the support bar, the vibration of the main body and thereby the noise during the vibration can be reduced.

Claims (5)

A support bar suspended from an upper part of the main body, a laundry dehydration bucket and an outer container for accommodating water, A slide cylinder through which the support bar passes; In the vibration isolator for a washing machine comprising a slide period which is in contact with the inner surface of the slide cylinder and can vibrate vertically and provided at the lower end of the support bar via a vibration insulation spring, A vibration isolation tube provided on an outer periphery of said vibration isolation spring; And further comprising a ring spring provided on the bottom inner surface of the slide cycle such that the slide cycle is in elastic contact with the inner surface of the slide cylinder, And the slide cycle has an air hole for penetrating the slide cycle into the slide cylinder. The washing machine according to claim 1, wherein the friction generated between the vibration isolation spring and the vibration insulation tube and the friction generated between the slide cylinder with the ring spring and the slide period are used as a damping effect. Vibration isolator for The vibration isolator of claim 1, wherein the air hole on the slide has an area suitable for almost eliminating the air damping effect at a higher rotational frequency of the washing and dewatering container. 2. The vibration isolator of claim 1, wherein grease is provided between the slide cycle and the slide cylinder. 5. The method according to any one of claims 1 to 4, wherein at the rotational frequency of the wash and dewatering sump equal to the natural frequency of the vibration system, the ratio between friction, viscosity and air damping ratio is less than 2 and the friction and viscosity The vibration isolator for a washing machine, characterized in that the sum of the damping ratios is equal to or greater than 8.