Shock absorber

Abstract

Disclosed herein is a shock absorber for damping vibration transmitted to a vehicle according to a road state. The shock absorber includes a cylinder and a piston valve disposed within the cylinder and connected to a piston rod to divide the cylinder into a first chamber and a second chamber. The piston rod includes a hollow chamber formed within the piston rod, first and second orifices formed in upper and lower ends of the hollow chamber and connected to the first and second chambers, respectively, a floating piston disposed within the hollow chamber to move up and down and to divide the hollow chamber into upper and lower chambers, and a moving mechanism formed in the hollow chamber to move an operating fluid to upper and lower portions of the floating piston. The shock absorber can change a damping force according to a displacement of the piston rod, thereby improving driving comfort and stability of the vehicle.

1 . A shock absorber comprising:
 a cylinder;   a piston valve connected to a piston rod within the cylinder to divide the cylinder into a first chamber and a second chamber;   a hollow chamber formed within the piston rod;   first and second orifices formed in upper and lower ends of the hollow chamber and in fluid communication with the first and second chambers, respectively;   a floating piston disposed within the hollow chamber to move up and down and to divide the hollow chamber into upper and lower chambers; and   a moving mechanism positioned in the hollow chamber to move an operating fluid above and below the floating piston.   
   
   
       2 . The shock absorber according to  claim 1  wherein the moving mechanism disposed within the hollow chamber is a bypass passage formed longitudinally in the hollow chamber to allow the upper chamber and the lower chamber to fluidly communicate with each other. 
   
   
       3 . The shock absorber according to  claim 1 , further comprising:
 an upper spring and a lower spring positioned in the upper chamber and the lower chamber to elastically support upper and lower surfaces of the floating piston, respectively.   
   
   
       4 . The shock absorber according to  claim 3  wherein the upper and lower springs are coil springs. 
   
   
       5 . The shock absorber according to  claim 3  wherein the upper and lower springs are conical coil springs, each having a gradually decreasing radius toward the floating piston. 
   
   
       6 . The shock absorber according to  claim 3  wherein the upper and lower surfaces of the floating piston are formed with mounting protrusions into which the upper and lower springs are fitted, respectively. 
   
   
       7 . The shock absorber according to  claim 2  wherein the bypass passage is a groove formed to have a predetermined length in the hollow chamber. 
   
   
       8 . The shock absorber according to  claim 2  wherein the bypass passage is an internal passage formed to have a predetermined length in the piston rod to connect the upper chamber and the lower chamber within the hollow chamber. 
   
   
       9 . The shock absorber according to  claim 1  wherein the moving mechanism includes a flexible moving plate disposed within the floating piston and configured to be deformed toward the upper or lower chamber during operation. 
   
   
       10 . The shock absorber according to  claim 9  wherein the floating piston comprises a ring, the ring having an inner surface, at least a portion of an outer circumference of the flexible moving plate being coupled to at least a portion of the inner surface, and an outer surface contacting an inner surface of the hollow chamber, and the flexible moving plate includes a bent part symmetrically formed with respect to a center of the bent part and alternately bent up and down. 
   
   
       11 . The shock absorber according to  claim 10 , wherein the bent part is thin near the ring and is thick at the center of the bent part. 
   
   
       12 . The shock absorber of  claim 10  wherein the bent part includes an outer circumference disposed on the inner surface of the ring.