Patent ID: 6981577

Claim:
A controllable damping force shock absorber comprising: a cylinder in which a variable viscosity fluid is sealably contained; a piston slidably disposed in the cylinder in a fitted relationship so as to divide the interior of the cylinder into two cylinder chambers; a piston rod having one end connected to the piston and the other end extended to the outside of the cylinder; and a damping force-controlling mechanism for generating a controlled damping force by controlling a flow of the variable viscosity fluid caused by slidable movement of the piston, the damping force-controlling mechanism including: a damping valve having a pressure-receiving portion for receiving a pressure of the variable viscosity fluid in at least one of an extension stroke and a compression stroke of the piston rod, a pilot chamber provided behind the pressure-receiving portion, wherein a pressure in the pilot chamber is applied in a direction for closing the damping valve so that the pilot chamber controls the opening of the damping valve and when the damping valve is opened, the variable viscosity fluid is allowed to flow from one of the cylinder chambers to the other without passing through the pilot chamber; a pilot passage for allowing the variable viscosity fluid to flow through the pilot chamber according to slidable movement of the piston; and viscosity-changing means adapted to change viscosity of the variable viscosity fluid flowing through the pilot passage so that the pressure in the pilot chamber varies depending on the change in the viscosity of the variable viscosity fluid.