Damper for damping vibration and washing machine having the same

Abstract

A damper for damping vibration and a washing machine having the same are disclosed. The damper includes a damper cylinder; a shaft inserted into the damper cylinder through one end of the damper cylinder, and reciprocating in the lengthwise direction of the damper cylinder; and a friction member provided on the shaft for damping vibration generated by friction with the inner wall of the damper cylinder, and moving vertically to the lengthwise direction of the damper cylinder. The damper adjusts damping force thereof according to vibrated states of an object to be vibrated, and has an improved vibration-damping effect.

1 . A damper comprising: 
 a damper cylinder;    a shaft inserted into the damper cylinder through one end of the damper cylinder, and reciprocating in the lengthwise direction of the damper cylinder; and    a friction member provided on the shaft for damping vibration by friction with the inner wall of the damper cylinder, and moving vertically to the lengthwise direction of the damper cylinder.    
     
     
         2 . The damper as set forth in  claim 1 , wherein the shaft includes a frictional force-adjusting device for moving the friction member to, adjust the frictional force between the friction member and the inner wall of the damper cylinder.  
     
     
         3 . The damper as set forth in  claim 2 , wherein the frictional force-adjusting device includes a pressure unit for pressing the friction member to move the friction member towards the inner wall of the damper cylinder to a designated distance.  
     
     
         4 . The damper as set forth in  claim 3 , wherein the pressure unit includes: 
 a first pressure member;    a second pressure member provided at one side of the first pressure member, and positioned opposite to the first pressure member; and    an interval adjuster for moving at least one of the first and second pressure members in the axial direction of the shaft in order to move the friction member.    
     
     
         5 . The damper as set forth in  claim 4 , wherein, when the first and second pressure members are close to each other, the frictional force between the friction member and the inner wall of the damper cylinder is increased.  
     
     
         6 . The damper as set forth in  claim 4 , wherein the first and second pressure members are disposed in the axial direction of the shaft, and at least one of the first and second pressure members includes at least one inclined portion inwardly inclined towards the other one of the first and second pressure members.  
     
     
         7 . The damper as set forth in  claim 6 , wherein the side surface of at least one of the first and second members is inclined such that the cross sectional area thereof is decreased close to the other one of the first and second members.  
     
     
         8 . The damper as set forth in  claim 6 , wherein the pressure unit further includes at least one slip member provided in the friction member to correspond to the inclined portion, and moving outwardly along the inclined portion to press the friction member when the first and second pressure members are close to each other.  
     
     
         9 . The damper as set forth in  claim 8 , wherein the friction member moves towards the center of the shaft and is separated from the inner wall of the damper cylinder when the first and second pressure members are distant from each other.  
     
     
         10 . The damper as set forth in  claim 9 , wherein the slip member includes an elastic member for returning the friction member to the center of the shaft when the first and second pressure members are distant from each other.  
     
     
         11 . The damper as set forth in  claim 10 , wherein the elastic member has a ring-shape, and is provided on the outer cylindrical surface of the slip member.  
     
     
         12 . The damper as set forth in  claim 8 , wherein, in the case that the pressure unit includes a plurality of slip members, the pressure unit further includes guide ribs provided on the outer cylindrical surface of at least one of the first and second pressure members for preventing the concentrated movement of the slip members in the circumferential direction.  
     
     
         13 . The damper as set forth in  claim 4 , wherein the interval adjuster moves the second pressure member.  
     
     
         14 . The damper as set forth in  claim 13 , the interval adjuster includes: 
 at least one connection rod passing through the first pressure member fixed to a body of the shaft, and connected to the second pressure member; and    a driving unit for driving the connection rods to move the second pressure member.    
     
     
         15 . The damper as set forth in  claim 14 , wherein the driving unit rectilinearly moves the connection rod to move the second pressure member.  
     
     
         16 . The damper as set forth in  claim 15 , wherein the driving unit includes an electromagnet provided at the other side of the first pressure member for rectilinearly moving the connection rod using magnetic force so that the second pressure member moves towards the first pressure member when current flows.  
     
     
         17 . The damper as set forth in  claim 16 , wherein the connection rod includes a metal member provided between the first pressure member and the electromagnet.  
     
     
         18 . The damper as set forth in  claim 15 , wherein the driving unit includes: 
 a wire connected to the connection rod; and    an actuator connected to the wire.    
     
     
         19 . The damper as set forth in  claim 14 , wherein the driving unit includes a motor for rotating the connection rod, and the second pressure member rectilinearly moves by the rotation of the connection rod.  
     
     
         20 . The damper as set forth in  claim 19 , wherein the connection rod passes through the second pressure member, and is connected to the second pressure member by a screw.  
     
     
         21 . The damper as set forth in  claim 18 , wherein the pressure unit further includes a guide pin, one end of which is inserted into the first pressure member and the other end of which is inserted into the second pressure member, for guiding the movement of the second pressure member.  
     
     
         22 . The damper as set forth in  claim 13 , wherein the interval adjuster includes: 
 an electromagnet provided on the first pressure member;    a metal member provided on the second pressure member; and    a guide rod passing through the second pressure member for guiding the movement of the second pressure member.    
     
     
         23 . The damper as set forth in  claim 22 , wherein the guide rod includes a stopper, one end of which is connected to one side of the electromagnet and the other end of which prevents the second pressure member from being separated from the guide rod.  
     
     
         24 . The damper as set forth in  claim 1 , wherein the friction member has a ring shape surrounding the outer cylindrical surface of the shaft.  
     
     
         25 . The damper as set forth in  claim 24 , wherein the friction member is made of an elastic material.  
     
     
         26 . The damper as set forth in  claim 1 , wherein the friction member contacts the inner wall of the damper cylinder when the number of vibration of an object to be vibrated is more than a designated value, and is separated from the inner wall of the damper cylinder when the number of vibration of the object is less than the designated value.  
     
     
         27 . The damper as set forth in  claim 1 , the frictional force between the friction member and the inner wall of the damper cylinder when the spin speed of an object for generating vibration is more than a designated speed is lower than that when the spin speed of the object is less than the designated speed.  
     
     
         28 . The damper as set forth in  claim 1 , wherein one of the damper cylinder and the shaft is connected to a tub of a washing machine, and the other one of the damper cylinder and the shaft is connected to a cabinet of the washing machine.