Patent ID: 6474454
Filing Date: 2002-11-05
Classification: F16F

Abstract:
A damping force control type hydraulic shock absorber comprising:a cylinder having a hydraulic fluid sealed therein; a piston slidably fitted in said cylinder to divide an inside of said cylinder into two chambers; a piston rod connected at one end thereof to said piston, the other end of said piston rod extending to the outside of said cylinder; a main passage and a sub-passage for allowing the hydraulic fluid to flow between said two chambers in response to sliding movement of said piston; a pilot-operated damping valve for generating damping force by controlling flow of the hydraulic fluid in said main passage, said pilot-operated damping valve including a valve member and a pilot chamber provided such that the pressure of the hydraulic fluid in the pilot chamber urges the valve member to the valve closing position; a fixed orifice provided in said sub-passage; a regulating valve provided in said sub-passage at a position downstream of said fixed orifice; a pilot passage for allowing a portion of said sub-passage between said fixed orifice and said regulating valve to communicate with said pilot chamber; and a restrictor provided in said pilot passage, wherein a portion of said pilot passage is defined by said valve member and a piston rod assembly comprising said piston rod and a piston bolt for securing said piston to said piston rod.