Hydraulic prosthetic joint

摘要

The present invention relates to artificial limbs generally and to joints for the same. In particular, the present invention provides hydraulic functional units (35), generally classified as damping devices as connected between artificial limbs whereby to enable movement of artificial joints to closely correspond with natural human movement. In the provision of realistic joints, as used in prosthetic limbs, an important aspect in attempting to achieve a realistic movement is to provide a different operating characteristic to the joint when under load. Indeed, one of the more important characteristics of an artificial leg for achieving a natural-looking walking gait correspond with those of a so called stabilized knee, i.e. a knee which resists flexion when under load, that is when it is bearing at least some of the weight of the amputee. In accordance with the invention, there is provided hydraulic damper control elements for prostheses which utilize a pressure differential due to the presence a fluid flow as a direct control input for a at least one hydraulic valve (47). The valve can comprise a vortex flow arrangement (47f) to cause fluid flow to circulate about aperture. The valve can comprise a moveable element which abuts a resiliently mounted element which reduces the size of an aperture as the force increases.

主权项

1. A prosthesis comprising:
a first artificial limb component; a second artificial limb component; a joint pivotally coupling said first and second artificial limb components to permit extension and flexion movements about the joint; and a hydraulic damper comprising a variable volume chamber for hydraulic fluid coupled between said first and second limb components; wherein the damper is operable to allow relative movement of said first and second limb components about the joint by passage of an incompressible hydraulic fluid through said variable volume chamber via an aperture of a valve, the valve being operable to determine a degree to which the hydraulic damper reactively resists a force to permit movement by a first pressure, which first pressure acts on a wall of the variable volume chamber; wherein the valve is disposed between the variable volume chamber and a hydraulic fluid sink on a second side of the valve; wherein a fluid flow rate of the incompressible hydraulic fluid through the valve is a conditioned function of a second pressure, which second pressure is less than the first pressure and is associated with fluid flow through the valve and is operable to maintain a positive flow rate through the valve as the first pressure increases, the conditioned function being characterized in that the second pressure as a function of the flow rate causes an increase in resistance of the valve to the flow caused by the first pressure, such that the fluid flow approaches but does not reach a maximum as the first pressure increases past a minimum pressure, whereby a fluid flow limit is established through the valve.