Patent ID: 8225913

Claim:
A damper for continuously variably adjusting a damping force, comprising: a cylinder; a piston rod that is inserted into the cylinder and moves back and forth; a piston valve that is coupled to a bottom portion of the piston rod and moves back and forth in the cylinder according to the movement of the piston rod; a MR fluid that fills the cylinder and moves between a tension space over the piston valve and a compression space below the piston valve; and a volume compensation means that is located in the cylinder and compensates for a volume change of an inner space of the cylinder due to the movement of the piston rod, the volume compensation means including: a floating plunger that is configured to be below the piston valve and capable of moving up and down; a coil spring that is coupled to a bottom surface of the floating plunger and supports the floating plunger; and a support cup that is fixed onto the cylinder, coupled to a bottom portion of the coil spring to support the coil spring, and forms a buffer space, along with the floating plunger, between the support cup and the floating plunger; wherein the volume compensation means further includes: an upper holder that prevents friction between the floating plunger and a top portion of the coil spring due to a direct contact therebetween; and a lower holder that prevents friction between the bottom portion of the coil spring and the support cup due to a direct contact therebetween; and wherein the floating plunger includes an upper insert shaft that protrudes downwardly from the bottom surface of the floating plunger, and the upper holder includes an insert hole at a central portion of the upper holder, wherein the upper insert shaft is fitted into the insert hole to couple the floating plunger and the upper holder, and a bottom portion of the upper holder is inserted into a bore of the coil spring to couple the upper holder and the coil spring.