Patent ID: 6997959

Claim:
A multi-functional artificial knee joint for connecting a prosthetic lower leg to a residual thigh of a prosthesis wearer, comprising: a joint seat having a joint body and a rotatable member that is connected pivotally to said joint body and that is adapted to be mounted to the thigh; a hollow support frame connected pivotally to said joint body; a first linkage unit connected to said support frame and said joint body; a hydraulic device disposed within said support frame and including a cylinder body, a piston rod, and a piston connected fixedly to said piston rod and disposed slidably within said cylinder body so as to divide an interior space in said cylinder body into an upper oil chamber and a lower oil chamber, said piston being driven by said first linkage unit to move within said cylinder body between an upper limit position and a lower limit position, said piston moving from said upper limit position to said lower limit position when said joint flexes to form an angle between the thigh and the lower leg, said piston moving from said lower limit position to said upper limit position when said joint extends to align the thigh with the lower leg; a safety device including a main body having a knee-flexing oil passage in fluid communication with said upper and lower oil chambers, and a knee-extending oil passage in fluid communication with said upper and lower oil chambers, a control valve unit for closing said knee-flexing oil passage during movement of said piston from said upper limit position to said lower limit position so as to permit oil flow from said lower oil chamber into said upper oil chamber through said knee-flexing oil passage, and for closing said knee-extending oil passage during movement of said piston from said lower limit position to said upper limit position so as to permit oil flow from said upper oil chamber into said lower oil chamber through said knee-extending oil passage, a first throttle valve disposed in said knee-flexing oil passage, and a controlling element disposed movably on said support frame and connected operatively to said first throttle valve, said controlling element being driven by said rotatable member to move relative to said support frame to activate said first throttle valve so as to stop oil flow through said knee-flexing oil passage, thereby fixing the thigh relative to the lower leg when the lower leg is pressed against the ground by the thigh; and an air valve unit disposed on said support frame and connected operatively to said first throttle valve, said air valve unit activating said first throttle valve to reduce flow rate of oil flowing through said knee-flexing oil passage in response to fast walking of the prosthesis wearer.