Prosthetic leg knee joint, braking device, and load position detector

Abstract

A prosthetic leg knee joint includes a thigh connection part that is provided on the thigh side, a lower leg part that is provided rotatably around a knee shaft connected to the thigh connection part, a four-bar link mechanism that sets an instant center S whose relative position with respect to the thigh connection part is substantially constant regardless of the relative position between the thigh connection part and the lower leg part, and a braking unit that brakes the movement of the lower leg part in accordance with the relative position between the instance center S set by the four-bar link mechanism and the lower leg part.

What is claimed is: 
     
         1 . A prosthetic leg knee joint comprising:
 a thigh connection part that is provided on the thigh side;   a lower leg part that is provided rotatably around a knee shaft connected to the thigh connection part;   a reference position setting unit that sets a reference position whose relative position with respect to the thigh connection part is substantially constant, regardless of the relative position between the thigh connection part and the lower leg part; and   a braking unit that brakes the movement of the lower leg part in accordance with the relative position between the reference position set by the reference position setting unit and the lower leg part.   
     
     
         2 . The prosthetic leg knee joint according to  claim 1 , wherein
 the reference position setting unit is a multi-bar link mechanism that is deformed in accordance with the relative position between the thigh connection part and the lower leg part,   the reference position represents an instant center that is set by the multi-bar link mechanism; and   the braking unit brakes the movement of the lower leg part when the multi-bar link mechanism is deformed to a predetermined degree or more.   
     
     
         3 . The prosthetic leg knee joint according to  claim 2 , wherein the multi-bar link mechanism consists of an upper link part provided in the thigh connection part, a lower link part provided in the braking unit, and a plurality of connection link parts that connect the upper link part and the lower link part. 
     
     
         4 . The prosthetic leg knee joint according to  claim 3 , wherein the length of the upper link part and the length of the lower link part are different. 
     
     
         5 . The prosthetic leg knee joint according to  claim 4 , wherein the length of the lower link part is shorter than the length of the upper link part. 
     
     
         6 . The prosthetic leg knee joint according to  claim 4 , wherein the length of the lower link part is longer than the length of the upper link part. 
     
     
         7 . The prosthetic leg knee joint according to  claim 3 , wherein the connection link parts include a front link part connecting a part of the upper link part and a part of the lower link part and a rear link part connecting another part of the upper link part and another part of the lower link part. 
     
     
         8 . The prosthetic leg knee joint according to  claim 5 , wherein the reference position is set between the vicinity of the sole and the vicinity of the hip joint of the prosthetic leg wearer. 
     
     
         9 . The prosthetic leg knee joint according to  claim 1 , wherein the reference position setting unit includes an upper link part provided in the thigh connection part, a lower link part provided in the braking unit, a connection link part connecting a part of the upper link part and a part of the lower link part, and a sliding element connecting another part of the upper link part and another part of the lower link part. 
     
     
         10 . A braking device comprising:
 a reference position setting unit that sets a reference position whose relative position with respect to a thigh connection part provided on the thigh side is substantially constant, regardless of the relative position between the thigh connection part and a lower leg part provided rotatably around a knee shaft connected to the thigh connection part; and   a braking unit that brakes the movement of the lower leg part in accordance with the relative position between the reference position set by the reference position setting unit and the lower leg part.   
     
     
         11 . A load position detector comprising:
 a reference position setting unit that sets a reference position whose relative position with respect to a thigh connection part that is provided on the thigh side is substantially constant, regardless of the relative positions of the thigh connection part and a lower leg part that is rotatable around a knee shaft connected to the thigh connection part; and   a detection unit that detects the relative position between the reference position set by the reference position setting unit and the lower leg part.   
     
     
         12 . A prosthetic leg knee joint comprising:
 a thigh connection part that is provided on the thigh side;   a lower leg part that is provided rotatably around a knee shaft connected to the thigh connection part;   a multi-bar link mechanism that sets an instant center, whose relative position with respect to the thigh connection part is substantially constant regardless of the relative position between the thigh connection part and the lower leg part, between the vicinity of the sole and the vicinity of the hip joint of the prosthetic leg wearer; and   a braking unit that brakes the movement of the lower leg part when the relative position between the instant center that has been set by the multi-bar link mechanism and the lower leg part is in a predetermined state due to the deformation of the multi-bar link mechanism, wherein   the multi-bar link mechanism consists of an upper link part provided in the thigh connection part, a lower link part provided in the braking unit, a front link part connecting a part of the upper link part and a part of the lower link part, and a rear link part connecting another part of the upper link part and another part of the lower link part, and   wherein the length of the lower link part is shorter than the length of the upper link part.