Patent ID: 8863918

Claim:
A hydraulic shock absorber comprising: an outer tube; an inner tube slidably inserted into the outer tube; a partition wall member provided in an inner periphery of the inner tube; an oil chamber defined at a lower side of the partition wall member; an oil reservoir chamber defined at an upper side of the partition wall member; a piston rod attached to the outer tube, the piston rod being slidably inserted into the inner tube through the partition wall member; and a piston coming into slidable contact with the inner periphery of the inner tube, the piston being fixed to a leading end portion of the piston rod inserted into the inner tube, wherein the piston comprises upper and lower pistons, the upper and lower pistons form upper and lower two stages and are fixed to the leading end portion of the piston rod, an upper side of the upper piston is provided with an upper oil chamber in which the piston rod is accommodated, a lower side of the lower piston is provided with a lower oil chamber in which the piston rod is not accommodated, an intermediate oil chamber is provided between the upper and lower pistons, an extension side damping force generating means is provided in a flow path which is provided in the upper piston and heads for the intermediate oil chamber from the upper oil chamber, and a compression side damping force generating means is provided in a flow path which is provided in the lower piston and heads for the intermediate oil chamber from the lower oil chamber, the partition wall member is provided with a volume compensating flow path which communicates the oil reservoir chamber with the oil chamber, an intermediate air chamber is provided in such a manner as to compensate an oil amount change in the oil chamber by coming into contact with the intermediate oil chamber and expanding and compressing on the basis of the oil amount change of the oil chamber caused by an extension and compression stroke of the piston rod, and an air compression rate of an upper portion air chamber of the oil reservoir chamber is set to be equal to or more than an air compression rate of the intermediate air chamber, with respect to the extension and compression stroke of the piston rod.