JPH04244196A - Drum-type washing machine - Google Patents

Abstract

PURPOSE:To effectively damp vibration of a drum-type washing machine in a simple constitution. CONSTITUTION:In a drum-type washer, a receiving drum in which a tumbler is mounted is held in a case through a spring and damper. A mass 21 having a given mass is slidably mounted in a cylinder 20 whose both ends are closed and elastically held in the middle of it with a spring 22. Moreover, a dynamic damper 5 in which a gas chamber 23 communicates with a gas chamber 24 which are formed on both sides of the mass 21 through an orifice 25 is provided to the receiving drum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vibration isolating means for a drum-type washing machine equipped with a horizontal rotating shaft.

0002

[Prior Art] A drum-type washing machine that performs washing, dehydration, and drying inside a drum equipped with a horizontal rotating shaft is shown in FIGS. 4 and 5, for example.
The drum 4 is supported by a structure as shown in FIG.

That is, a washing tank 2 containing a drum 4 that can freely rotate is suspended by four coil springs 3 inside a case 1 placed on a floor 10, while one end is connected to the lower part of the case 1. The drum 4 is supported from below by two dampers 11.

[0004] This is to prevent the drum 4 from vibrating greatly when the laundry is not evenly pressed against the inner periphery of the drum 4 during spin-drying and the rotation of the drum 4 becomes unbalanced.

[0005] A motor 7 for rotationally driving the drum 4 is attached to the lower part of the washing tub 2, and transmits rotational force to the drum 4 via a belt 9. Further, laundry is loaded into the drum 4 through a door 13 provided on the side of the case 1.

[0006]

The vibration absorption mechanism of the drum 4 in this case is shown in the model of FIG. According to this model,
The centrifugal force P, the equation of motion, and the vibration transmission rate τ to the floor 10 are as shown in Equation 1.

[0007]

[Math 1]

FIG. 7 shows a graph of the relationship between the vibration transmissibility τ and the vibration coefficient ratio η in equation (1) using the damping coefficient ratio ζ as a parameter.

As is clear from this graph, the resonance point (η=
1) In the nearby low-speed rotation range, the larger the damping coefficient ratio ζ, the smaller the vibration transmissibility τ, and therefore the higher the vibration damping effect.However, in the high-speed rotation range, which is the steady rotation range during dehydration, the damping coefficient ratio ζ The larger the value, the greater the vibration transmissibility τ.

However, during dewatering, the rotational speed of the drum 4 increases from 0 to 1000 rpm, and on the way it passes a resonance point, so as shown in the graph, the damper 11 is turned on to suppress vibrations at this resonance point. When the damping coefficient ratio ζ is set, there is a problem in that the vibration transmissibility τ becomes higher in a higher speed steady rotation range, and a desirable vibration damping effect cannot be obtained.

In order to solve this problem, the damping force generated by the damper 11 may be changed in accordance with the rotation speed of the drum 4.
This requires an actuator to change the damping force, a controller to drive the actuator, a sensor to detect vibrations, etc., making the overall configuration complicated.

It is also known that the legs 12 that support the case 1 on the floor 10 are made of rubber, but in the case of rubber, it is difficult to arbitrarily set the spring constant, so It was difficult to obtain a damping effect.

The present invention has been made to solve the above-mentioned problems, and its object is to more effectively suppress the vibrations of a drum-type washing machine with a simple structure.

[0014]

[Means for Accomplishing the Object] The present invention provides a drum-type washing machine in which a laundry receiving tank with a rotating drum housed inside is supported inside a case via a spring and a damper. A dynamic mass having a predetermined mass is housed in the dynamic mass and is elastically held in an intermediate position by a spring, and a dynamic damper is provided in which the gas chambers defined on both sides of the dynamic mass are communicated through an orifice. It is attached to the laundry tank.

[0015]

[Function] By equipping a dynamic damper with a natural frequency that matches the excitation frequency of the drum in the steady rotation range during dewatering, the dynamic damper displaces in the opposite phase to the drum in the steady rotation range and cancels the drum vibration. Vibration is significantly reduced.

Furthermore, since the flow resistance of the gas flowing through the orifice as the dynamic mass is displaced regulates the amplitude of the mass, the dimensions of the dynamic damper are reduced.

[0017]

[Embodiment] An embodiment of the present invention will be explained using FIGS. 1 to 3. Note that the same components as those in the conventional example are given the same numbers and detailed explanations will be omitted.

As shown in FIG. 1, a dynamic damper 5 is attached to the washing tub 2.

As shown in FIG. 2, the dynamic damper 5 has a cylindrical dynamic mass 21 slidably housed inside a cylinder 20 whose both ends are sealed, and a coil interposed between both ends of the cylinder 20. It is held at an intermediate position by a spring 22.

Dynamic mass 2 inside the cylinder 20
Air chambers 23 and 24 are defined on both sides of the dynamic mass 21, and an orifice 25 provided vertically through the center of the dynamic mass 21 communicates with these air chambers 23 and 24.

A mounting bolt 26 is fixed to one end of the cylinder 20, and the dynamic damper 5 is mounted to the lower surface of the washing tub 2 via this mounting bolt 26.

The mass of the dynamic mass 21 and the spring constant of the coil spring 22 are set so that the natural frequency of the dynamic mass 21 matches the excitation frequency in the steady rotation range of the drum 4 during dewatering. The other configurations are the same as those of the conventional example.

Next, the operation will be explained.

The drum 4 supported by the coil spring 3 and the damper 11 increases its rotational speed when the washing machine enters the dewatering stage, and passes through a resonant frequency on the way up. The vibration of the drum 4 at this resonant frequency is damped by the damper 11 as in the conventional example.

Furthermore, when the rotational speed of the drum 4 increases and reaches a steady rotation range, the dynamic mass 21 inside the dynamic damper 5 vibrates in response to the vibration of the drum 4. At this time, the dynamic mass 21 is the drum 4 (washing tank 2)
Since the drum 4 slides in the cylinder 20 in a direction opposite to the displacement of the drum 4, the vibration of the drum 4 is canceled out, and almost no vibration is transmitted to the case 1.

In this manner, in the steady rotation range of the drum 4, the vibration transmissibility τ is significantly reduced by the action of the dynamic damper 5, as shown in FIG.

Note that as the dynamic mass 21 slides, the coil spring 22 is alternately bent, and air flows between the expanding and contracting air chambers 23 and 24 via the orifice 25. Since the amplitude of the dynamic mass 21 is regulated by the damping force produced by the flow resistance, the vibrating dynamic mass 21 does not collide with the end face of the cylinder 20. Therefore, the dimensions of the dynamic damper 5 can be reduced while maintaining the necessary damping effect.

[0028]

Effects of the Invention As described above, the present invention has a dynamic damper whose amplitude is limited by gas flow resistance in the washing tank that accommodates the drum of a drum-type washing machine. Vibration isolation in the rotation range can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of a drum-type washing machine showing an embodiment of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of the dynamic damper.

FIG. 3 is a graph of vibration transmissibility.

FIG. 4 is a schematic longitudinal cross-sectional view of a conventional drum-type washing machine.

FIG. 5 is a schematic perspective view as well.

FIG. 6 is a front view of the vibration absorption model.

FIG. 7 is a graph of vibration transmissibility.

[Explanation of symbols]

1 Case 2 Laundry tank 3,22 Coil spring 4 Drums 5 Dynamic damper 11 Damper 20 Cylinder 21 Dynamic mass 23, 24 Air chamber 25 Orifice

Claims (1)

[Claims] Claim 1: In a drum-type washing machine in which a laundry receiving tank with a rotating drum housed inside is supported inside a case via a spring and a damper, a dynamic washing machine with a predetermined mass is placed inside a cylinder whose both ends are sealed. A dynamic damper is attached to the laundry receiving tub, in which the mass is housed in a freely sliding manner and is elastically held in an intermediate position by a spring, and the gas chambers defined on both sides of the dynamic mass are communicated through an orifice. Drum type washing machine.