Brace and tension springs for a brace

1. A brace for augmenting extension of a user's limb about a joint, comprising

an upper arm having an engaging portion for engaging against the user's limb above the joint, and an attachment portion,

a lower arm having an engaging portion for engaging against the user's limb below the joint, and an attachment portion, the lower arm being pivotable relative to the upper arm,

at least one compression element disposed in fixed relation to at least one of the upper and lower arms, and

a substantially inelastic tensioning element affixed to the other of the upper and lower arms over at least one tensioning element tensioning member such that applying a force to bend the brace to a flexed position loads the compression element, and upon removal of the flexing force the compression element applies a restoring force to urge the brace back to an extended position,

the compression element comprising a hydraulic tension spring disposed in fixed relation to at least the other of the upper and lower arms, comprising

a pair of cylinders mounted within a frame, each cylinder having a sealed portion defining a liquid containment space,

for each of the pair of cylinders,

a piston comprising a piston rod, the piston rod comprising a compressing portion having a smaller diameter than the cylinder and extending axially through a hydraulic seal into the liquid containment space, and

an external portion accessible from outside the liquid containment space,

one of the cylinder and the piston being fixed relative to the frame and the other of the cylinder and the piston being movable axially relative to the frame,

a guide for maintaining the movable one of the cylinder and the piston oriented axially relative to the frame, and

a compression element tensioning member bearing against the movable one of the at least one cylinder and the piston, for compressing the at least one cylinder relative to the piston,

whereby when the frame is fixed in place and tension is applied to the tensioning element tensioning member, the compressing portions of the piston rods intrude further into the liquid containment space, compressing the hydraulic fluid and loading the spring.

2. The brace of claim 1 wherein the tensioning element is attached to the other of the upper and lower arms via a second compression element fixed to the other of the upper and lower arms.

3. The brace of claim 2 wherein the lower arm attachment portion and the upper arm attachment portion are pivotally connected to a connecting element.

4. The brace of claim 3 wherein the at least one tensioning element tensioning member comprises at least one pivot connecting the upper arm or the lower arm to the connecting element.

5. The brace of claim 4 wherein the at least one pivot comprises a circumferential groove for retaining the tensioning element.

6. The brace of claim 1 comprising a plurality of tensioning element tensioning members.

7. The brace of claim 1 wherein the at least one tensioning element tensioning member is mounted eccentrically.

8. The brace of claim 1 wherein the at least one tensioning element tensioning member is non-circular.

9. The brace of claim 1 wherein the at least one tensioning element tensioning member is free-rotating.

10. The brace of claim 1 wherein the at least one tensioning element tensioning member is fixed in relation to one of the upper and lower arms or a gusset joining the arms together.

11. A brace for augmenting extension of a user's limb about a joint, comprising

an upper arm having an engaging portion for engaging against the user's limb above the joint, and an attachment portion,

a lower arm having an engaging portion for engaging against the user's limb below the joint, and an attachment portion, the lower arm being pivotable relative to the upper arm,

a substantially inelastic tensioning element affixed to one of the upper and lower arms over at least one tensioning element tensioning member such that applying a force to bend the brace to a flexed position loads a compression element, and upon removal of the flexing force the compression element applies a restoring force to urge the brace back to an extended position, and

the compression element comprising at least one hydraulic tension spring disposed in fixed relation to at least the other of the upper and lower arms, comprising

at least one cylinder having a sealed portion defining a liquid containment space,

for each of the at least one cylinders,

a piston comprising a piston rod, the piston rod comprising

a compressing portion having a smaller diameter than the cylinder and extending axially through a hydraulic seal into the liquid containment space, and

an external portion accessible from outside the liquid containment space,

one of the cylinder and the piston being fixed relative to a frame and the other of the cylinder and the piston being movable axially relative to the frame,

a guide for maintaining the movable one of the cylinder and the piston oriented axially relative to the frame, and

a compression element tensioning member bearing against the movable one of the at least one cylinder and the piston, for compressing the at least one cylinder relative to the piston,

whereby when the frame is fixed in place and tension is applied to the compression element tensioning member, the compressing portion of the piston rod intrudes further into the liquid containment space, compressing the hydraulic fluid and loading the spring.

12. The brace of claim 11 wherein applying a tensioning force to the compression element tensioning member draws a piston rod cap against the piston, the piston rod cap being positioned so as to apply force axially to the external portion of the piston rod.

13. The brace of claim 11 wherein the hydraulic tension spring comprises a plurality of cylinders and pistons, wherein the piston rod cap is positioned so as to apply force axially to the external portions of each of the piston rods and the compression element tensioning member applies force to the piston rods centrally between the cylinders so as to apply the axial force equally to the external portion of each piston rod.

14. The brace of claim 11 wherein the tensioning element is attached to the one of the upper and lower arms via a second compression element fixed to the one of the upper and lower arms.

15. The brace of claim 14 wherein the lower arm attachment portion and the upper arm attachment portion are pivotally connected to a connecting element.

16. The brace of claim 15 wherein the at least one tensioning element tensioning member comprises at least one pivot connecting the upper arm or the lower arm to the connecting element.

17. The brace of claim 16 wherein the at least one pivot comprises a circumferential groove for retaining the tensioning element.

18. The brace of claim 11 wherein the at least one tensioning element tensioning member is mounted eccentrically.

19. The brace of claim 11 wherein the at least one tensioning element tensioning member is non-circular.

20. The brace of claim 11 wherein the at least one tensioning element tensioning member is free-rotating.