Anti-vibration device

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 anti-vibration device on the tub.

1 . A washing machine comprising:
 a housing;   a tub in the housing;   a laundry drum rotatably mounted in the tub; and   an anti-vibration device on the tub.   
   
   
       2 . The washing machine according to  claim 1 , wherein the anti-vibration device provides anti-vibration at a predetermined frequency. 
   
   
       3 . The washing machine according to  claim 1 , wherein the anti-vibration device provides anti-vibration at a first predetermined frequency and a second predetermined frequency. 
   
   
       4 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises a mass in communication with a spring. 
   
   
       5 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises:
 a hollow tube having a longitudinal axis; and   a mass suspended between longitudinal ends of the hollow tube by a pair of springs having a predetermined stiffness.   
   
   
       6 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises:
 a hollow tube having a longitudinal axis; and   a first mass and a second mass arranged in series and suspended between longitudinal ends of the hollow tube, wherein the first mass and the second mass are coaxial with the longitudinal axis of the hollow tube;   a first spring that connects a first end of the hollow tube to a first end of the first mass;   a second spring that connects a second end of the first mass to a first end of the second mass, wherein the second end of the first mass is adjacent to the first end of the second mass; and   a third spring that connects a second end of the second mass to a second end of the hollow tube.   
   
   
       7 . The washing machine according to  claim 6 , wherein a mass of the first mass is substantially equal to a mass of the second mass. 
   
   
       8 . The washing machine according to  claim 6 , wherein a stiffness of the first spring is substantially equal to a stiffness of the third spring. 
   
   
       9 . The washing machine according to  claim 8 , wherein a stiffness of the second spring is different from the stiffness of the first spring or the stiffness of the third spring. 
   
   
       10 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises a damping device. 
   
   
       11 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises a variable damping device. 
   
   
       12 . The washing machine according to  claim 1 , wherein the anti-vibration device comprises a variable mass device or a variable spring stiffness device. 
   
   
       13 . The washing machine according to  claim 1 , wherein the hollow tube is filled with a viscous fluid. 
   
   
       14 . The washing machine according to  claim 13 , wherein the viscous fluid is a variable viscosity fluid. 
   
   
       15 . The washing machine according to  claim 14 , further comprising:
 an element on the hollow tube for changing a viscosity of the variable viscosity fluid within the hollow tube.   
   
   
       16 . The washing machine according to  claim 15 , further comprising:
 a controller in communication with the element.   
   
   
       17 . The washing machine according to  claim 16 , wherein the controller receives an input from a motion detector. 
   
   
       18 . The washing machine according to  claim 1 , further comprising:
 a counter balance weight on the tub,   wherein the anti-vibration device is on the counter balance weight.   
   
   
       19 . The washing machine according to  claim 1 , wherein the anti-vibration device includes a plurality of anti-vibration devices on the tub. 
   
   
       20 . An apparatus comprising:
 an outer cylinder;   an inner cylinder rotatably mounted in the outer cylinder; and   an anti-vibration device on the outer cylinder.