EP2072653A1

EP2072653A1 - Washing machine with anti-vibration device

Info

Publication number: EP2072653A1
Application number: EP08105933A
Authority: EP
Inventors: Huiyu Fang; Ramon Rodriguez; Oliver SCHÖNE
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2007-12-18
Filing date: 2008-12-03
Publication date: 2009-06-24
Also published as: US20090151398A1; CA2645978A1

Abstract

A washing machine is provided. The washing machine includes a housing, a tub disposed in the housing, a laundry drum rotatably mounted in the tub, and an antivibration device on the tub.

Description

Field of Disclosure

The present invention relates to a washing machine, and more particularly, to a washing machine having an anti-vibration device on an oscillating system, including a washing tub.

Background

A conventional washing machine typically includes a housing. A tub is disposed in the housing and a laundry drum is rotatably mounted in the tub. With the conventional washing machine, clothes are placed in the laundry drum and washing, rinsing and hydro-extracting tasks are automatically carried out according to a prescribed program. After washing and rinsing of the clothes, excess water is removed from the laundry drum by centrifugal force created by the laundry drum rotating (i.e., spinning) at high speeds.
A conventional washing machine typically is a rotordynamic system with an unbalanced washing load resulting, for example, from the clothes in the laundry drum being unevenly arranged. Under a high spinning speed of the laundry drum, the unbalanced load may create a severe asymmetric centrifugal force that may cause the entire oscillating system to vibrate, for example, in a wobbling fashion.
In conventional washing machines, various types of mechanical mechanisms have been developed and implemented to attempt to reduce the off-balance vibration.
For example, conventional washing machines have added structure-damping and/or mass-damping to the housing to attempt to address off-balance vibration. In most conventional washing machines, counterweights also have been attached to the tub to address vibration of the washing machine to attempt to reduce the magnitude of vibration of the laundry drum. Other conventional washing machines have attached, for example, a liquid-filled balance ring, a movable ball dynamic balancer, etc. to the spinning drum to attempt to address off-balance vibration.

SUMMARY

Conventionally, the focus on reducing vibrations has been on the laundry drum and the housing. However, the conventional washing machines leave room for improvement in addressing the wobbling of the washing machine, for example, under high speed spinning of the laundry drum. In comparison, the exemplary aspects of the invention focus on reducing vibrations on the tub, instead of on the laundry drum and the housing.
For example, an exemplary embodiment is directed to a washing machine including a housing, a tub disposed in the housing, a laundry drum rotatably mounted in the tub, and an anti-vibration device on the tub.
Another exemplary embodiment is directed to an apparatus including an outer cylinder, an inner cylinder rotatably mounted in the outer cylinder, and an anti-vibration device on the outer cylinder.
The anti-vibration device may provide a vibration which is directed opposed to the vibration of the tub, especially a vibration ob the tub caused by an uneven distributed laundry within the drum during spinning. A washing machine having an anti-vibration device according to the embodiments of the invention may reduce the wobbling of the washing machine based on one or more frequencies of the system under a high speed spinning by providing an anti-vibration device on the tub. The anti-vibration device may provide anti-vibration at one or more predetermined frequencies or ranges of frequencies, and more particularly, anti-resonance at one or more resonant frequencies or ranges of resonant frequencies. Moreover, the anti-vibration device according to embodiments of the invention may provide adjustability for a variety of frequencies.
Accordingly, the exemplary aspects of the invention may reduce or eliminate vibration of the tub, and more particularly, may reduce or eliminate the wobbling motion of the tub under high spinning speeds of the laundry drum, which may range from 0-1200 RPM, or higher, in some washing machines.
The features of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of exemplary embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description of embodiments of the invention and are provided solely for illustration of the embodiments and not limitation thereof.
FIG. 1 is a schematic front view of a washing machine according to an embodiment of the invention.
FIG. 2 is a schematic front view of a washing machine according to another embodiment of the invention.
FIG. 3 is a schematic side view of a washing machine according to another embodiment of the invention.
FIG. 4 is a schematic front view of a washing machine according to another embodiment of the invention.
FIG. 5 is a schematic front view of a washing machine according to another embodiment of the invention.
FIG. 6 is a schematic side view of a washing machine according to another embodiment of the invention.
FIG. 7 is a schematic view of an anti-vibration device according to an embodiment of the invention.
FIG. 8 is a schematic of an energy absorbing feature according to an aspect of the invention.
FIG. 9 is a schematic of an energy absorbing feature according to another aspect of the invention.
FIG. 10 is a schematic of an energy absorbing feature according to another aspect of the invention.
FIG. 11 is a graph showing a typical function describing the housing vibration magnitude in a washing machine spinning process.
FIG. 12 is another graph showing a function describing the housing vibration magnitude in a washing machine spinning process according to an embodiment of the invention.
FIG. 13 is a perspective view of an anti-vibration device according to an embodiment of the invention.
FIG. 14 is a perspective view of another anti-vibration device according to another embodiment of the invention.
FIG. 15 is a perspective view of another anti-vibration device according to an embodiment of the invention.
FIG. 16 is a perspective view of another anti-vibration device according to an embodiment of the invention.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the scope of the invention. Additionally, well-known elements of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention.
The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term "embodiments of the invention" does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.
With reference to FIGS. 1-16, exemplary embodiments of the invention will now be described.
As shown in FIG. 1, a washing machine according to an embodiment of the invention may include a housing 2, a tub 6 disposed in the housing 2, and a laundry drum 4 rotatably mounted in the tub 6. An anti-vibration device 10 may be on the tub.
The ordinarily skilled artisan will recognize that the anti-vibration device 10 is not limited to providing anti-vibration at a single frequency. The anti-vibration device may reduce vibrations on the tub 6 at one or more predetermined frequencies or ranges of frequencies. More particularly, the anti-vibration device may provide anti-resonance at one or more resonant frequencies or ranges of resonant frequencies. For example, aspects of the anti-vibration device 10 may provide anti-vibration, for example, at a first predetermined frequency (e.g., a first resonant frequency) and a second predetermined frequency (e.g., a second resonant frequency).
As exemplarily illustrated in FIGS. 1-6, more than one anti-vibration device 10 may be mounted on the tub 6 of the washing machine at various positions to optimize the anti-vibration affects, and more particularly, the anti-resonance affects, of the anti-vibration device 10.
For example, as illustrated in FIGS. 1 and 2, one or more anti-vibration devices 10 may be on (e.g., mounted on or mounted directly on) the tub 6. The ordinarily skilled artisan will recognize that other arrangements of one or more anti-vibration devices 10 on the tub 6 may be provided within the spirit and scope of the invention.
FIG. 3 shows a side view of an assembly having a laundry drum 4 and tub 6, according to an aspect of the invention. During high speed spinning of the laundry drum 4 within the tub 6, the magnitude of vibration at the front end 56 of the tub 6 generally will be greater than the magnitude of vibration at the rear end 58 of the tub 6. That is, a higher magnitude of vibration generally will occur at the front end 56 of the tub 6. Accordingly, in an embodiment of the invention, one or more anti-vibration devices 10 may be provided on the front end 56 of the tub 6.
FIGS. 4 and 5 show other embodiments in which the anti-vibration device 10 may be on one or more counter balance weights 8, such as concrete weights, which are on the tub 6. The ordinarily skilled artisan will recognize that one or more anti-vibration devices 10 may be on each of the counter balance weights 8. The ordinarily skilled artisan also will recognize that other arrangements of the counter balance weights 8 on the tub 6 may be provided.
FIG. 6 shows a side view of an assembly having a laundry drum 4 and tub 6, according to another aspect of the invention. As set forth above, a higher magnitude of vibration generally will occur at the front end 56 of the tub 6. Accordingly, in an embodiment of the invention, one or more anti-vibration devices 10 may be provided on one or more counter balance weights 8 on the front end 56 of the tub 6. As further illustrated in FIG. 6, the anti-vibration devices 10 may be provided directly on the tub 6 and/or on the counter balance weights 8.
FIG. 7 is a schematic view of an anti-vibration device 10 according to an embodiment of the invention. The anti-vibration device 10 may include an energy absorbing feature (e.g., a vibration absorbing feature) 22 that reduces the kinetic energy of the tub at a predetermined frequency or at a plurality of frequencies, such as a first predetermined frequency and a second predetermined frequency. In another embodiment, the anti-vibration device 10 having the energy absorbing feature 22 may provide anti-resonance at a resonant frequency, or at a plurality of resonant frequencies, such as a first resonant frequency and a second resonant frequency. Moreover, the anti-vibration device 10 having the energy absorbing feature 22 may provide anti-vibration at a range of frequencies, or anti-resonance at a range of resonant frequencies.
For example, FIG. 8 shows an exemplary aspect of a single degree of freedom (1 DOF) energy absorbing feature 22 having a mass in communication with two springs. One of ordinary skill in the art will recognize that the frequency f of the single degree of freedom (1 DOF) system can be determined according to the equation: $f = \frac{1}{2 π} \sqrt{\frac{2 k_{0}}{m_{0}}}$

where m ₀ is the mass and k ₀ is the spring stiffness.
FIG. 9 shows another exemplary aspect of a two degree of freedom (2 DOFs) energy absorbing feature 22 having a first spring, a first mass, a second spring, a second mass, and a third spring arranged in series. One of ordinary skill in the art will recognize that the frequency f ₁ and frequency f ₂ of the exemplary two degree of freedom (2 DOFs) system can be determined according to the equations: $f_{1} = \frac{1}{2 π} \sqrt{\frac{k_{0}}{m_{0}}}$
$f_{2} = \frac{1}{2 π} \sqrt{\frac{k_{0} + 2 k_{1}}{m_{0}}}$

where the first mass and second mass may have substantially the same mass m ₀, the first spring and third spring may have substantially the same spring stiffness k ₀, and the second spring may have a spring stiffness k ₁, which may be different than the spring stiffness k ₀.
FIG. 10 shows an exemplary aspect of a two degree of freedom (2 DOF) energy absorbing feature 22 having a spring-mass-damping mechanism. As shown in FIG. 10, dampers having a damping coefficient c may be arranged to be parallel to the first spring, second spring, and third spring.
FIG. 11 shows a graph of a frequency response function for an apparatus without an anti-vibration device. In comparison, FIG. 12 is a graph showing a frequency response function for an apparatus having an anti-vibration device 10 according to an exemplary embodiment of the invention. As shown in FIG. 12, an anti-vibration device 10 having a vibration absorbing device 22 may provide frequency bifurcation, which may reduce the amplitude of the frequency.
According to the exemplary aspects of the invention, the mass and spring stiffness may be fine tuned to reduce the kinetic energy of the tub 6 at one or more predetermined frequencies or range of frequencies, thereby reducing the wobbling effect on the washing machine.
With reference to FIGS. 13-16, exemplary embodiments of an anti-vibration device 10 will now be described.
The anti-vibration device 10 may include, for example, a hollow tube 20 having a longitudinal axis. The hollow tube 20 may be, for example, a hollow plastic tube, metal tube, or the like. The hollow tube 20 may be, for example, a cylindrical hollow tube as shown in FIGS. 13-16, or another shape of a hollow tube, such as a box-shaped or square-shaped hollow tube or the like.
The ends of the hollow tube 20 may include a first mounting cap 12, which is attached to a first end of the hollow tube 20, and a second mounting cap 14, which is attached to a second end of the hollow tube 20. The mounting caps 12 and 14 may be, for example, made of metal, plastic, etc. The mounting caps 12 and 14 also may provide a secure mounting surface for the ends of the anti-vibration device 10.
Each of the first mounting cap 12 and the second mounting cap 14 also may include an attachment element, such as mounting holes 16 and 18, respectively, for mounting the anti-vibration device 10 on, for example, the tub 6 or on a counter balance weight 8, which is on the tub 6. The ordinarily skilled artisan will recognize that other attachment elements, such as other female connectors or fittings, male connectors or fittings, adhesives, welds, etc. may be used to mount or secure the anti-vibration device 10.
In the exemplary embodiment illustrated in FIG. 13, the anti-vibration device 10 may include a mass 26 suspended between longitudinal ends of the hollow tube 20 by a pair of springs 24 and 28. Each of the springs 24 and 28 may have a predetermined stiffness k. The mass 26 may have a mass m ₀. As shown in FIG. 13, the mass 26 may be configured to be coaxial with the longitudinal axis of the hollow tube 20.
In the exemplary embodiment shown in FIG. 14, the anti-vibration device 10 may include a first mass 32 and a second mass 36 arranged in series and suspended between longitudinal ends of the hollow tube 20. The first mass 32 and the second mass 36 may be configured to be coaxial with the longitudinal axis of the hollow tube 20. FIG. 14 shows an exemplary aspect in which the mass m ₀ of the first mass 32 may be substantially equal to the mass m ₀ of the second mass 36.
As shown in FIG. 14, a first spring 30 connects a first end of the hollow tube 20 to a first end of the first mass 32. A second spring 34 connects a second end of the first mass 32 to a first end of the second mass 36. As shown in FIG. 14, the second end of the first mass 32 is adjacent to the first end of the second mass 36. A third spring 38 connects a second end of the second mass 36 to a second end of the hollow tube 20. FIG. 14 shows an exemplary aspect in which a stiffness k ₁ of the first spring 30 may be substantially equal to a stiffness k ₁ of the third spring 38. A stiffness k ₂ of the second spring 34 may be different from the stiffness k ₁ of the first spring 30 and/or the second spring 38.
The embodiment of the anti-vibration device 10 having the first mass 32, the second mass 36, and the springs 30, 34, and 38 may provide anti-vibration, for example, at two predetermined frequencies, and more particularly, anti-resonance, for example, at two predetermined resonant frequencies. Accordingly, the exemplary embodiments may provide a fine-tuned anti-vibration device 10 on the tub 6 that may provide anti-vibration, and more particularly, anti-resonance.
In an embodiment, the anti-vibration device 10 may be suspended within the hollow tube 20 without contacting an inner surface of the hollow tube 20. By avoiding contact between the components of the anti-vibration device 10, such as the masses 32 and 36 in FIG. 14, and the inner surface of the hollow tube 20, the embodiments may improve performance and reduce wear on the anti-vibration device 10.
To further reduce wear on the anti-vibration device 10, the hollow tube 20 may be filled with a viscous fluid 40 to reduce or prevent friction between the masses (e.g., 32 and 36) and the inner surface of the hollow tube 20, as shown in FIG. 15. The embodiment may include rubber bushings 42 and 44 that are connected to each of a first end and a second end of the hollow tube 20 to hermetically seal the hollow tube 20 and prevent the viscous fluid 40 from leaking from the hollow tube 20.
In other exemplary embodiments, the anti-vibration device 10 may include a damping device, or a variable damping device which has a variable damping coefficient c. For example, the viscous fluid 40 in the hollow tube 20 can provide damping in the anti-vibration device 10.
In the embodiment of FIG. 16, a variable viscosity fluid 46 may be used to provide a variable damping device, thereby providing anti-vibration at variable frequencies. For example, the variable viscosity fluid 46 may be a temperature sensitive viscous fluid that changes viscosity in response to changes in temperature of the fluid, or a magnetic responsive fluid (eg. magnetorheologic fluid) that changes viscosity in response to magnetic forces, or an electric responsive fluid (eg. electrorheologic fluid) that changes viscosity in response to electric field. The ordinarily skilled artisan will recognize that the variable viscosity fluid 46 may be responsive to other stimulus that may change the viscosity of the fluid. By changing the viscosity of the fluid the damping coefficient c may be variable adjusted.
The variable viscosity fluid 46 may be used to provide anti-vibration at variable frequencies, thereby permitting the washing machine to operate at a larger acceptable range of spinning speeds of the laundry drum.
In other embodiments, the mass of one or more masses of the anti-vibration device 10 may be variable. In an embodiment, a mass of the anti-vibration device 10 may be variable, for example, by changing an amount of a liquid in the mass (e.g., in a cavity formed in the mass).
In another embodiment, the stiffness of one or more springs of the anti-vibration device 10 may be variable. In an embodiment, the stiffness of one or more springs of the anti-vibration device 10 may be variable, for example, in response to stimulus, such as temperature, electromagnetic forces, etc.
Referring again to FIG. 16, an element 48 may be mounted on the hollow tube 20 for changing viscosity of the variable viscosity fluid 46. For example, the element 48 may be a heating element used to change the temperature of the variable viscosity fluid 46, thereby adjusting a viscosity of the variable viscosity fluid 46 within the hollow tube 20. In case of a magnetorheologic fluid 46 the element 48 may be an electromagnet or in case of a electrorheologic fluid 46 the element 48 may also be an element comprising at least two electrodes. The element 48 may be electrically connected by a wire 50 to a controller 52, which may receive an input from a motion detector 54. The motion detector 54 may be any device that detects motion, such as an accelerometer, a linear motion detector, an optical motion sensor, etc. The controller 52 and the element 48 may build up a open loop control dependent on the drum speed or the controller 52, the element 48 and the motion detector 54 may build up a closed loop vibration control.
The ordinarily skilled artisan will recognize that one or more vibration attenuation devices on the housing 2 and/or the laundry drum 4 may be used in cooperation with the anti-vibration device 10 on the tub 6, according to embodiments of the invention.
While the foregoing disclosure shows illustrative embodiments of the invention with reference to a washing machine, it is nevertheless not intended to be limited to the details shown. For example, another embodiment of the invention is directed to an apparatus including an outer cylinder, an inner cylinder rotatably mounted in the outer cylinder, and an anti-vibration device on the outer cylinder.
It should be noted that various changes and modifications could be made herein without departing from the scope of the invention as defined by the appended claims and a range of equivalents thereof. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims

A washing machine comprising:
a housing (2);

a tub (6) in the housing (2);

a laundry drum (4) rotatably mounted in the tub (6); and

an anti-vibration device (10) on the tub (6),
wherein the anti-vibration device (10) provides anti-vibration at one or more predetermined frequencies or ranges of frequencies, especially at a first and/or at a second predetermined frequency.
The washing machine according to claim 1, wherein the anti-vibration device (10) comprises a mass (26, 32, 36) in communication with a spring (24, 28, 30, 34, 38).
The washing machine according to claim 1 or claim 2, wherein the anti-vibration device (10) comprises:
a hollow tube (20) having a longitudinal axis; and

a mass (26) suspended between longitudinal ends of the hollow tube (20) by a pair of springs (24, 26) having a predetermined stiffness.
The washing machine according to claim 1 or claim 2, wherein the anti-vibration device (10) comprises:
a hollow tube (20) having a longitudinal axis; and

a first mass (32) and a second mass (36) arranged in series and suspended between longitudinal ends of the hollow tube (20), wherein the first mass (32) and the second mass (36) are coaxial with the longitudinal axis of the hollow tube (20);

a first spring (30) that connects a first end of the hollow tube (20) to a first end of the first mass (30);

a second spring (34) that connects a second end of the first mass (32) to a first end of the second mass (36), wherein the second end of the first mass (30) is adjacent to the first end of the second mass (36); and

a third spring (38) that connects a second end of the second mass (36) to a second end of the hollow tube (20).
The washing machine according to claim 4, wherein a mass of the first mass (32) is substantially equal to a mass of the second mass (36).
The washing machine according to claim 4 or claim 5, wherein a stiffness of the first spring (30) is substantially equal to a stiffness of the third spring (38).
The washing machine according to claim 6, wherein a stiffness of the second spring (34) is different from the stiffness of the first spring (30) or the stiffness of the third spring (38).
The washing machine according to one of the preceding claims, wherein the anti-vibration device (10) comprises a damping device having a damping coefficient c.
The washing machine according to claim 8, wherein the damping coefficient c is variable.
The washing machine according to one of the preceding claims, wherein the anti-vibration device (10) comprises a variable mass device or a variable spring stiffness device.
The washing machine according to one of the claim 3 to 10, wherein the hollow tube (20) is filled with a viscous fluid (40, 46).
The washing machine according to claim 11, wherein the viscous fluid is a variable viscosity fluid (46), particularly a fluid that changes viscosity in response to changes in temperature of the fluid, to magnetic forces or to an electric field.
The washing machine according to claim 12, further comprising:
an element (48) on the hollow tube (20) for changing a viscosity of the variable viscosity fluid (46) within the hollow tube (20).
The washing machine according to claim 13, further comprising:
a controller (52) in communication with the element (48).
The washing machine according to claim 14, wherein the controller (52) receives an input from a motion detector (54).
The washing machine according to one of the preceding claims, further comprising:
a counter balance weight (8) on the tub (6),
wherein the anti-vibration device (10) is on the counter balance weight (8).
The washing machine according to one of the preceding claims, wherein the anti-vibration device (10) includes a plurality of anti-vibration devices (10) on the tub (6).
An apparatus comprising:
an outer cylinder;

an inner cylinder rotatably mounted in the outer cylinder; and

an anti-vibration device on the outer cylinder.