HYDRAULIC CONTROL UNIT FOR PROSTHETIC LEG

摘要

A prosthetic leg (10) has a pivotal knee joint (18) and a hydraulic fluid control unit (20) connected to provide variable forces which dampen flexion and extension of the knee and also bias the leg to its extended position. The unit includes an aluminum housing (22) lined with an axially adjustable sleeve (48) and control bushing (55) defining a cylindrical chamber (85) which receives a piston (70) mounted on a tubular piston rod (28). The housing and chamber receive hydraulic fluid or oil which flows during movement of the piston through fluid control ports (60), channels (62) and adjustable gaps (96, 98) defined by t he sleeve and bushing for damping the movement of the rod. The piston rod encloses a gas filled flexible bladder (140) which forms an oil accumulator during inward movement of the piston rod and also produces variable forces for moving the piston rod outwardly to its extended position. The housing confines a gap defining ring (97) which compensates for changes in oil viscosity with heat.