Stabilized artificial knee mechanism

Abstract

An artificial leg has a stabilized knee mechanism, that is, a mechanism which resists flexion of the leg when the latter is under load. The leg has upper and lower leg components, for example thigh and shin, and the knee mechanism includes a hollow brake drum with a brake shoe inside it. The drum is connected to the thigh and the shoe to the shin. The shoe frictionally engages the inner surface of the drum to resist flexion of the leg when it is under load.

We claim: 
     
       1. An artificial leg having relatively movable upper and lower components and a stabilised knee mechanism, which mechanism comprises a hollow brake drum and a brake shoe .Iadd.means .Iaddend.inside the drum .Iadd.for engaging the inner surface thereof.Iaddend., the drum being connected to one of the said components and the shoe being connected to the other of the said components, .[.and means responsive to movement of one of the said components relative to the other of said components, which movement results from application of a load on the leg, the said means causing the.]. .Iadd.which brake .Iaddend.shoe .Iadd.means .Iaddend.frictionally .[.to engage.]. .Iadd.engages .Iaddend.the inner surface of the drum so as to resist flexion of the .[.knee mechanism.]. .Iadd.components when the leg is under load, and which brake shoe means comprises a part-cylindrical, resilient means, the improvement wherein the said brake shoe means is connected to the other of the said components by a toggle joint action in such a manner that relative approaching movement of the said components causes the said brake shoe means to expand inside the said brake drum.Iaddend.. 
     
     
       2. An artificial leg according to claim 1 including release means for assisting disengagement of the .Iadd.brake .Iaddend.shoe .Iadd.means .Iaddend.and the drum. 
     
     
       3. An artificial leg according to claim 2 wherein the release means comprises one or more springs urging relative movement apart of the said components.  .[.4. An artificial leg according to claim 1 wherein the drum is rigidly connected to the upper component and wherein the brake shoe comprises a part cylindrical resilient member pivotally connected to the lower component such that relative movement of one component towards the other causes expansion of the shoe inside the drum and frictional engagement of the shoe with the drum..]. .[.5. An artificial leg according to claim 4 wherein the lower component is pivotally attached to an outer end portion of a radius arm member about a bearing axis parallel and anterior to the drum axis, the inner end portion of the arm member being pivotally attached to the upper leg component about the drum axis..]. .[.6. An artificial leg according to claim 5 wherein the bearing axis is within the geometrical cylinder formed by the inner surface of the drum..]. .[.7. An artificial leg according to claim 4 wherein the brake shoe has two ends which are both individually connected to the lower 
     
     
        component, one end being connected via a pivoting link member..]. 8. An artificial leg according to claim 1 including means for adjusting the clearance between the .Iadd.brake .Iaddend.shoe .Iadd.means .Iaddend.and 
     
     
        the drum when the leg is under zero load. 9. An artificial leg according to claim 1 wherein the upper component is a thigh and the lower component is a shin, a fluid swing phase control unit being connected to the shin and thigh. .Iadd. 10. An artificial leg according to claim 1, wherein the brake shoe means is connected to the said lower component, a first pivot joint being connected at one end of the brake shoe means, a second pivot joint being connected at the other end of the brake shoe means, and a third pivot joint being mounted by the lower component in such manner that the three pivot joints constitute a toggle joint, whereby the relative approaching movement of the said components causes the first and second pivot joints to be moved apart by the toggle joint to expand the brake shoe means inside the brake drum. .Iaddend..Iadd. 11. An artificial leg according to claim 10, in which the drum is rigidly connected to the said upper component, and wherein the said lower component is pivotally attached to an outer end portion of a radius arm member at the first pivot joint whose axis is parallel and anterior to the drum axis, the inner end portion of the radius arm member being pivotally attached to the said upper component at the drum axis. .Iaddend..Iadd. 12. An artificial leg according to claim 3 further comprising a radius arm member having its outer end portion pivotally attached to the lower component and its inner end portion pivotally attached to the upper component and wherein the release means comprises a compression coil spring bearing at one end against a rod which is connected to the outer end of the radius arm member and at the other end against the said lower component. .Iaddend..Iadd. 13. An artificial leg according to claim 10 wherein the first pivot joint is within the geometrical cylinder formed by the inner surface of the brake drum. .Iaddend..Iadd. 14. An artificial leg according to claim 1, wherein the two ends of the brake shoe means are separately connected to the said lower component, one of the said two ends being connected to said lower component by a link member which is pivotally connected to said one end and to said lower component. .Iaddend. .Iadd. 15. An artificial leg according to claim 1 wherein said drum is rigidly connected to one of the said components. .Iaddend..Iadd. 16. An artificial leg having relatively movable upper and lower components and a stabilised knee mechanism, which mechanism comprises a hollow drum and a brake shoe means inside the drum for engaging the inner surface thereof, the drum being connected to one of the said components and the shoe being connected to the other of the said components, which brake shoe means frictionally engages the inner surface of the drum so as to resist flexion of the components when the leg is under load, and which brake shoe means comprises a part-cylindrical, resilient means, the improvement wherein the said brake shoe means is connected to the other of the said components by a toggle joint action in such a manner that relative approaching movement of the said components causes the said brake shoe means to expand inside the said drum, and wherein said brake shoe means includes two ends separately connected to said other of the said components, one of said two ends being connected to said other component by a link member which is pivotally connected to said one end and to said other component. .Iaddend.