Hydraulic cylinders for limb gait control
First Claim
1. A hydraulic control unit for use with a prosthetic leg assembly of the type having a load-bearing linkage system or a single axis-knee assembly for providing flexion and extension of a leg, the hydraulic control unit comprising:
- a pair of cylinders aligned in eccentric relation to each other, one of the pair of cylinders being a fluid confining control cylinder and a second of the pair of cylinders being an inner cylinder, the inner cylinder being within the control cylinder and defining a fluid reservoir therein, with a gap being a spacing between the control cylinder and the inner cylinder, the gap defining a fluid displacement chamber and having a size that is larger on one side of the inner cylinder than on an opposite side;
a series of openings in the inner cylinder for passing fluid between the fluid reservoir and the fluid displacement chamber with the size of the gap adjacent to the openings being adjustable by a rotational position of the control cylinder;
a piston assembly having a rod with an inner portion extending into the inner cylinder, an outer portion projecting from the inner cylinder, and a first piston located on the inner portion of the piston rod within the fluid reservoir;
a supply of hydraulic fluid within each of the fluid reservoir and the fluid displacement chamber, the fluid flowing through said series of openings in response to axial movement of the piston and piston rod within the fluid reservoir to effect damping of the piston rod; and
means for adjusting the rotational position between the control cylinder and the inner cylinder.
1 Assignment
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Accused Products
Abstract
A hydraulic cylinder control unit for gait control of a prosthetic limb which features two cylindrical tubes that are eccentric with respect to each other. The inner tube houses hydraulic fluid and the gap between the two tubes serves as a displacement chamber as a piston, mounted on a piston rod, moves through the fluid in the inner tube. When the outer tube is rotated about the inner tube, the gap between the tubes changes which either increases or decreases the flow allowed between the tubes. This changes the resistance which controls the rate of swing of an artificial limb. The resistance is easily adjustable by a simple rotation of the outer cylindrical tube. A floating sealed piston is additionally provided at the bottom of the inner tube. The sealed piston moves upwards or downwards depending on the balance of forces between the fluid force above the piston and the stored energy force below the sealed piston. The stored energy force can be either a spring or compressed gas and helps to return stored energy to the system and reduces the amount of energy required by the person in walking.
86 Citations
21 Claims
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1. A hydraulic control unit for use with a prosthetic leg assembly of the type having a load-bearing linkage system or a single axis-knee assembly for providing flexion and extension of a leg, the hydraulic control unit comprising:
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a pair of cylinders aligned in eccentric relation to each other, one of the pair of cylinders being a fluid confining control cylinder and a second of the pair of cylinders being an inner cylinder, the inner cylinder being within the control cylinder and defining a fluid reservoir therein, with a gap being a spacing between the control cylinder and the inner cylinder, the gap defining a fluid displacement chamber and having a size that is larger on one side of the inner cylinder than on an opposite side; a series of openings in the inner cylinder for passing fluid between the fluid reservoir and the fluid displacement chamber with the size of the gap adjacent to the openings being adjustable by a rotational position of the control cylinder; a piston assembly having a rod with an inner portion extending into the inner cylinder, an outer portion projecting from the inner cylinder, and a first piston located on the inner portion of the piston rod within the fluid reservoir; a supply of hydraulic fluid within each of the fluid reservoir and the fluid displacement chamber, the fluid flowing through said series of openings in response to axial movement of the piston and piston rod within the fluid reservoir to effect damping of the piston rod; and means for adjusting the rotational position between the control cylinder and the inner cylinder. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A hydraulic control unit for use with a prosthetic leg assembly, of the type having a load-bearing linkage system or a single axis knee assembly for providing flexion and extension of a leg, the hydraulic control unit comprising:
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an inner fixed cylinder and a rotatable fluid tight control cylinder surrounding the inner cylinder, and defining a fluid reservoir within the inner cylinder, the control cylinder having an eccentric rotational relation to the inner cylinder such that there is a gap between the inner cylinder and the control cylinder, the gap defining a fluid displacement chamber and having a size that is larger on one side of the inner cylinder than on an opposite side; a series of openings between the inner cylinder and the control cylinder for passing fluid between the fluid reservoir of the inner cylinder and the gap defining the fluid displacement chamber; a piston assembly having a rod with an inner portion extending into the inner cylinder and an outer portion projecting from the inner cylinder, with a first piston being located on the inner portion of the piston rod within the fluid reservoir; a supply of hydraulic fluid within each of the fluid reservoir and the gap defining the fluid displacement chamber, the fluid flowing between said fluid reservoir and the gap defining the fluid displacement chamber in response to axial movement of the first piston and the piston rod within the fluid reservoir to effect damping the piston rod; a floating sealed movable, second piston within the inner cylinder and defining a bottom side of the fluid reservoir, the floating sealed second piston being movable through the inner cylinder to compensate for fluid displaced by the piston rod entering or leaving the fluid reservoir as the piston assembly moves within the fluid reservoir and having a stored energy force means applied on a bottom side of the second piston for returning stored energy to the piston assembly; and means for adjusting the rotational position between the control cylinder and the inner cylinder, thereby adjusting the size of the gap on a side of the inner cylinder adjacent to the series of openings. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A hydraulic control unit for use with a prosthetic leg assembly of the type having a load-bearing linkage system or a single axis knee assembly for providing flexion and extension of a leg, the hydraulic control unit comprising:
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a pair of cylinders aligned in eccentric relation to each other, one of the pair of cylinders being a fluid confining control cylinder and a second of the pair of cylinders being an inner cylinder, the inner cylinder being within the control cylinder and defining a circumference of a fluid reservoir with a gap being the spacing between the inner cylinder and the control cylinder, the gap defining a fluid displacement chamber and having a size that is larger on one side of the inner cylinder than on an opposite side; a number of extension resistance and flexion resistance holes on a side of the inner cylinder for passing fluid between the fluid reservoir of the inner cylinder and the fluid displacement chamber; a piston assembly having a rod with an inner portion extending into the inner cylinder and an outer portion projecting from the inner cylinder with a first piston being located on the inner portion of the piston rod within the fluid reservoir, wherein the first piston and piston rod may axially move through the fluid reservoir; a supply of hydraulic fluid within each of the fluid reservoir and the gap defining the fluid displacement chamber, the fluid flowing through said extension resistance holes and said flexion resistance holes in response to the axial movement of the first piston and the piston rod within the fluid reservoir to effect damping of the piston rod; a floating sealed, movable second piston, within the inner cylinder and defining a bottom side of the fluid reservoir, the floating sealed second piston having a stored energy force means applied on a bottom side of the second piston for returning stored energy to the piston assembly, the floating sealed piston being movable through the inner cylinder to compensate for fluid displaced by the piston rod entering or leaving the fluid reservoir as the piston assembly moves within the fluid reservoir; and an accumulation chamber being located within the inner cylinder, beneath the floating sealed piston; means for adjusting a rotational position between the control cylinder and the inner cylinder thereby adjusting the size of the gap which defines the fluid displacement chamber on a side of the inner cylinder adjacent to the extension resistance and flexion resistance holes. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification