Prosthetic foot with energy transfer including variable orifice
View Patent ↗A prosthetic foot device with variable stiffness response includes a variable energy transfer mechanism or variable resistance cell disposed between first and second foot members to transfer a variable amount of energy from the second member to the first member during use. The energy transfer mechanism or variable resistance cell includes a variable orifice with variable size to variably resist flow of fluid therethrough, and thus variably transfers energy between the first and second members to vary stiffness of the prosthetic foot device.
1. A prosthetic foot device with variable stiffness response, the device comprising:
a) a primary elongated foot member, couplable to the stump of an amputee, and extending therefrom, defining an elongated spring capable of storing energy during deflection and having a resistance response to an applied force;
b) a secondary foot member, defining a secondary elongated resilient spring, disposed adjacent to the primary foot member;
c) an enclosure, disposed between the primary foot member and the secondary foot member;
d) a fluid path, in fluid communication with the enclosure;
e) a reservoir, in fluid communication with the fluid path;
f) a fluid, disposed in the enclosure and displaceable between the reservoir and the enclosure through the fluid path in response to the applied force; and
g) a variable orifice, operatively disposed in the fluid path, having a variable size operable to change the size of the variable orifice between a relatively larger size in response to a relatively smaller applied force from the primary foot member such that more fluid flows therethrough, and a relatively smaller size in response to a relatively larger applied force from the primary foot member such that less fluid flows therethrough to provide variable resistance against fluid flow therethrough, and to variably transfer the applied force from the primary foot member to the secondary foot member.
2. A prosthetic foot device in accordance with claim 1 , wherein the variable orifice variably transfers energy between the primary foot member and secondary foot member during use, increasing resistance to fluid flow between the enclosure and reservoir with an increase in the applied force to transfer more load between the primary foot member and secondary foot member during the increase in the applied force, and decreasing resistance to fluid flow during a decrease in the applied force to transfer less load between the primary foot member and secondary foot member during the decrease in the applied force.
3. A prosthetic foot device in accordance with claim 1 , wherein the enclosure is a flexible bladder.
4. A prosthetic foot device in accordance with claim 1 , wherein the variable orifice includes a servo-valve, operatively disposed between the enclosure and the reservoir and operable to restrict the fluid flow between the enclosure and reservoir.
5. A prosthetic foot device in accordance with claim 1 , wherein the enclosure is compressible between:
a) a first position, in response to a relatively larger applied force having a first larger dimension and in which a lesser amount of the fluid passes through the variable orifice into the reservoir; and
b) a second position, in response to a relatively smaller applied force having a second smaller dimension and in which a greater amount of the fluid passes through the variable orifice into the reservoir.
6. A prosthetic foot device in accordance with claim 1 , wherein the enclosure is compressible between the primary foot member and the secondary foot member.
7. A prosthetic foot device in accordance with claim 1 , wherein the primary foot member is a forefoot member extending to a toe location of a natural toe.
8. A prosthetic foot device in accordance with claim 7 , further comprising:
a) a primary heel member, couplable to the stump of an amputee, and extending therefrom to a heel location of a natural heel, defining an elongated spring capable of storing energy during deflection and having a resistance response to an applied force;
b) a secondary heel member, defining a secondary elongated resilient spring, disposed adjacent to the primary heel member;
c) a second enclosure, disposed between the primary heel member and the secondary heel member;
d) a fluid path, in fluid communication with the second enclosure;
e) a second reservoir, in fluid communication with the fluid path;
f) a fluid, disposed in the second enclosure and displaceable to the second reservoir through the fluid path in response to the applied force; and
g) a variable orifice, operatively disposed in the fluid path, having a variable size to provide variable resistance against fluid flow therethrough, to variably transfer the applied force from the primary heel member to the secondary heel member.
9. A prosthetic foot device in accordance with claim 8 , wherein the second enclosure defines the reservoir for the first enclosure and the first enclosure defines the reservoir for the second enclosure.
10. A prosthetic foot device in accordance with claim 1 , wherein the fluid is a variable viscosity fluid.
11. A prosthetic foot device in accordance with claim 1 , wherein the enclosure further comprises:
a) a chamber, associated with one of the primary and secondary foot members;
b) a piston, associated with another of the primary and secondary foot members and movable in the chamber, the piston and chamber defining a volume that changes in response to the load factor; and
c) at least one aperture, formed through the piston and in communication with the chamber.
12. A prosthetic foot device in accordance with claim 1 , wherein the fluid is displaceable from the enclosure to the reservoir and from the reservoir to the enclosure through the fluid path in response to the applied force.
13. A prosthetic foot device in accordance with claim 1 , wherein the secondary foot member is disposed near the stump of the amputee and extends therefrom to a point above the primary foot member.
14. A prosthetic foot device with variable stiffness response, the device comprising:
a) a primary elongated forefoot member, couplable to the stump of an amputee, and extending therefrom to a toe location of a natural toe, defining an elongated spring capable of storing energy during deflection and having a resistance response to an applied force;
b) a secondary forefoot member, defining a secondary elongated resilient spring, disposed adjacent to the primary elongated forefoot member;
c) a primary heel member, couplable to the primary forefoot member, and extending therefrom to a heel location of a natural heel, defining an elongated spring capable of storing energy during deflection and having a resistance response to an applied force;
d) a secondary heel member, defining a secondary elongated resilient spring, disposed adjacent to the primary heel member;
e) a first enclosure, disposed between the primary forefoot member and the secondary forefoot member;
f) a second enclosure, disposed between the primary heel member and secondary heel member;
g) a fluid path, in fluid communication with the first and second enclosures;
h) a fluid, disposed in the first and second enclosures and displaceable between the first and second enclosures through the fluid path in response to the applied force; and
i) a variable orifice, operatively disposed in the fluid path, having a variable size to provide variable resistance against fluid flow therethrough, to variably transfer the applied force from the primary forefoot member to the secondary forefoot member, and from the primary heel member to the secondary heel member.
15. A prosthetic foot device in accordance with claim 14 , wherein the variable orifice variably transfers fluid between the first enclosure and second enclosure during use, increasing resistance to fluid flow between the first enclosure and second enclosure with an increase in the applied force to transfer more load between the primary forefoot member and secondary forefoot member, or the primary heel member and the secondary heel member, during the increase in the applied force, and decreasing resistance to fluid flow during a decrease in the applied force to transfer less load between the primary forefoot member and secondary forefoot member, or the primary heel member and secondary heel member, during the decrease in the applied force.
16. A prosthetic foot device in accordance with claim 14 , wherein the first and second enclosures are flexible bladders.
17. A prosthetic foot device in accordance with claim 14 , wherein the variable orifice includes a servo-valve, operatively disposed between the first enclosure and the second enclosure and operable to restrict the fluid flow between the first enclosure and second enclosure.
18. A prosthetic foot device in accordance with claim 14 , wherein the first and second enclosures are compressible between:
a) a first position, in response to a relatively larger applied force having a first larger dimension and in which a lesser amount of the fluid passes through the variable orifice; and
b) a second position, in response to a relatively smaller applied force having a second smaller dimension and in which a greater amount of the fluid passes through the variable orifice.
19. A prosthetic foot device in accordance with claim 14 , wherein the first enclosure is compressible between the primary forefoot member and the secondary forefoot member, and the second enclosure is compressible between the primary heel member and secondary heel member.
20. A prosthetic foot device in accordance with claim 14 , wherein the first and second enclosures each include:
a) a chamber, associated with one of the primary and secondary foot members;
b) a piston, associated with another of the primary and secondary foot members and movable in the chamber, the piston and chamber defining a volume that changes in response to the load factor; and
c) at least one aperture, formed through the piston and in communication with the chamber.
21. A prosthetic foot device with variable stiffness response, the device comprising:
a) a primary elongated foot member, couplable to the stump of an amputee, and extending therefrom, defining an elongated spring capable of storing energy during deflection and having a resistance response to an applied force;
b) a secondary foot member, defining a secondary elongated resilient spring, disposed adjacent to the primary foot member;
c) an enclosure, disposed between the primary foot member and the secondary foot member;
d) a fluid path, in fluid communication with the enclosure;
e) a reservoir, in fluid communication with the fluid path;
f) a fluid, disposed in the enclosure and displaceable from the enclosure to the reservoir and from the reservoir to the enclosure through the fluid path in response to the applied force; and
g) means for variably resisting fluid flow between the enclosure and the reservoir including a variable orifice operable between a relatively larger size in response to a relatively smaller applied force from the primary foot member such that more fluid flows therethrough, and a relatively smaller size in response to a relatively larger applied force from the primary foot member such that less fluid flows therethrough, to variably transfer the applied force from the primary foot member to the secondary foot member.