Prosthetic leg with extension auxiliary mechanism
First Claim
1. A prosthetic leg with a knee joint, comprising an upper thigh member to which a load of a wearer is incurred through the thigh, a lower thigh member connected to said upper thigh member at the knee portion, and a knee joint including at least two front and rear links, one being located forwardly of the knee and the other being located backwardly of the knee, said two links together with said upper thigh member and said lower thigh member constituting a constrained chain, said upper thigh member and said lower thigh member being bendably connected together through said knee joint, wherein an extension auxiliary mechanism having a spring is disposed between said front link and said rear link, said extension auxiliary mechanism generates an extension torque determined by a product of a force caused by biasing of said spring and a distance from a line of action of said force to the center of rotation of said rear link, and said distance becomes approximately zero when a bending angle of the knee exceeds a predetermined angle.
1 Assignment
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Accused Products
Abstract
There is provided a prosthetic leg with an extension auxiliary mechanism 1100 capable of generating an extension torque only when an angle of bending of the knee is small. A knee joint 80 of a thigh prosthesis 170 is of a multi-axis structure, and a front and a rear link 130, 150 together with an upper thigh member 110 and a lower thigh member 120 constitutes a constrained chain. An extension auxiliary mechanism 1100 having a compression spring is supported between the lower thigh member 120 and the rear link 150. An extension torque generated by the extension auxiliary mechanism 1100 is determined by a product of a force caused by biasing of the compression spring and a distance from a line of action of the force to the center of rotation of the rear link 150. Here, at a stage where the bending angle of the knee exceeds, for example, 15 degrees, an axis of the compression spring is brought generally into alignment with a connecting portion 170O between the rear link 150 and the lower thigh member 120. By doing so, the distance related to the extension torque becomes approximately zero and the extension torque itself becomes approximately zero.
87 Citations
14 Claims
- 1. A prosthetic leg with a knee joint, comprising an upper thigh member to which a load of a wearer is incurred through the thigh, a lower thigh member connected to said upper thigh member at the knee portion, and a knee joint including at least two front and rear links, one being located forwardly of the knee and the other being located backwardly of the knee, said two links together with said upper thigh member and said lower thigh member constituting a constrained chain, said upper thigh member and said lower thigh member being bendably connected together through said knee joint, wherein an extension auxiliary mechanism having a spring is disposed between said front link and said rear link, said extension auxiliary mechanism generates an extension torque determined by a product of a force caused by biasing of said spring and a distance from a line of action of said force to the center of rotation of said rear link, and said distance becomes approximately zero when a bending angle of the knee exceeds a predetermined angle.
- 10. A prosthetic leg with a knee joint, comprising an upper thigh member to which a load of a wearer is incurred through the thigh, a lower thigh member connected to said upper thigh member at the knee portion, and a knee joint including at least two front and rear links, one being located forwardly of the knee and the other being located backwardly of the knee, said two links together with said upper thigh member and said lower thigh member constituting a constrained chain, said upper thigh member and said lower thigh member being bendably connected together through said knee joint, said prosthetic leg further comprising an extension auxiliary mechanism disposed between said front link and said rear link, said extension auxiliary mechanism generating an extension torque for extending the knee when a bending angle of the knee is smaller than a predetermined angle, and a swing phase control unit for generating a substantial acting force when a bending angle of the knee is larger than the predetermined angle.
Specification