Orthopedic fluid damper and method
The invention relates to an orthopaedic aid, in particular to a prosthesis ( 58 ) or orthosis comprising an orthopaedic fluid damper ( 10 ) with a displacement chamber ( 14 ) formed in a housing ( 12 ), with a piston ( 16 ) mounted in the displacement chamber ( 14 ), with a fluid reservoir for a fluid ( 20 ), with a return flow conduit ( 22 ) connecting the displacement chamber ( 14 ) to the fluid reservoir, with a valve ( 24 ) that can adopt an open position and a closed position, in which it at least partially closes the return flow conduit ( 22 ), and with a joint ( 72 ) that has a first branch ( 60 ) and a second branch ( 66 ), wherein the first branch ( 60 ) is connected to the housing ( 12 ) and the second branch ( 66 ) is connected to the piston ( 16 ). A device ( 84 ) is also provided for detecting a joint force (FB) acting on the joint, which device ( 84 ) is designed to bring the valve ( 24 ) to the closed position when the joint force (FB) exceeds a predefined threshold value. The invention also relates to a method for control of the aid and a fluid damper ( 10 ) fitted therein.
1. An orthopaedic having an orthopaedic fluid damper comprising:
(a) a displacement chamber formed in a housing,
(b) a piston mounted in the displacement chamber,
(c) a fluid reservoir for a fluid,
(d) a backflow line which connects the displacement chamber to the fluid reservoir,
(e) a valve which can assume an opening position and a closing position, in which the valve is operative to at least partially close the backflow line,
(f) a joint which has a first limb and a second limb, the first limb being connected to the piston,
(g) a bar attached at a proximal end to the first limb of the joint at a point of axial rotation and resiliently attached at a distal end to the second limb so as to allow only axial movement of the second limb with respect to the bar, the housing being connected to the distal end of the bar, and
(h) a force sensing device for detecting a joint force (F B ) acting on the joint, which is designed in order to bring the valve into the closing position when the joint force (F B ) overshoots a preset threshold value.
2. The orthopaedic aid as claimed in claim 1 , wherein the orthopaedic aid is a leg prosthesis with a knee joint, and the force sensing device for detecting the joint force acting on the knee joint is a leg-axis force sensor for detecting a leg-axis force acting in the axial direction (L) of the leg prosthesis.
3. The orthopaedic aid as claimed in claim 2 , further comprising an electric control which is connected electrically to the leg-axis force sensor and is designed for the electrical activation of the valve.
4. The orthopaedic aid as claimed in claim 1 , wherein the force sensing device for detecting the joint force is set up mechanically and, when loaded, displaces the valve into the closing position.
5. The orthopaedic aid as claimed in claim 4 , wherein the force sensing device for detecting the joint force is designed as a buckling spring, spring, cam guide or slotted guide or as a lever system.
6. The orthopaedic aid as claimed in claim 4 , the force sensing device is coupled to a solenoid valve.
7. The orthopaedic aid as claimed in claim 4 , wherein the force sensing device is designed such that displacement dependent on a pivot angle φ of the limbs with respect to one another causes actuation of a switching element in relation to the valve.
8. The orthopaedic aid as claimed in claim 1 , wherein the two limbs are mounted one on the other so as to be axially displaceable to a limited extent in relation to one another.
9. The orthopaedic aid as claimed in claim 1 , wherein the resilient attachment of the bar and the second limb is a spring acting in the axial direction and the spring acts counter to an axial displacement of the first and second limbs toward one another.
10. The orthopaedic aid as claimed in claim 1 , wherein the damper and the first limb of the joint are mounted together on the bar so as to be displaceable in relation to the second limb.
11. The orthopaedic aid as claimed in claim 10 , wherein the resilient attachment of the bar and the second limb is a spring arranged between the bar and the second limb and acts counter to a displacement of the second limb towards the bar.
12. The orthopaedic aid as claimed in claim 10 , wherein the damper and the first limb of the joint are mounted together on the bar which is shiftable, in relation to the second limb.
13. The orthopaedic aid as claimed in claim 1 , wherein the hydraulic damper is designed as a cylinder.
14. The orthopaedic aid as claimed in claim 1 , wherein the orthopaedic aid is a prosthesis or orthesis.
15. A method for controlling an orthopaedic aid as claimed in claim 1 , with the steps:
(a) detection of the joint force (F B ) acting on the joint, and
(b) activation of the valve such that it at least partially closes the backflow line.
16. The method as claimed in claim 15 , wherein the joint is a knee joint, and the detected joint force is a leg-axis force (F B ) which acts in the axial direction (L) of the leg prosthesis.
17. The method as claimed in claim 16 , wherein the valve is activated such that it at least partially closes the backflow line when the leg-axis force (F B ) overshoots a preset closing threshold value.
18. The method as claimed in claim 15 , wherein the valve is activated such that it enables the backflow line when the leg-axis force (F B ) undershoots a preset enabling threshold value.
19. The method as claimed in claim 15 , wherein the valve is switched independently of a position of the limbs.
20. The method as claimed in claim 15 , wherein the valve is switched as a function of an angle φ of the limbs.
21. The method as claimed in claim 15 , wherein the valve is switched mechanically such that a relative movement of the limbs in relation to one another is transmitted to the valve.