Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Leg – Knee
Patent
1994-05-24
1996-08-13
Willse, David H.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Leg
Knee
623 46, 188319, 267124, A61F 264
Patent
active
055452337
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a swing phase control device for an artificial knee joint.
In a swing phase control device of this kind the movement of the piston into the piston and cylinder arrangement and thus the flexion of the artificial knee joint can be controlled by the first throttle. When stretching the knee joint again the person using the artificial knee joint must swing the lower leg back in front and into a position aligned with the upper leg. The throttle effect occurring in this case is the same as that of the flexion. Since, however, the flexion and the stretching are separate processes, an identical throttle effect causes an unnatural course of motion. Whilst the throttle is adjustable and can therefore be adapted to the respective walking style, no dynamic adaptation to different courses of motion of the person is provided. Thus, the throttle has an optimum effect either for slow or for fast motions only.
It is therefore the object of the invention to provide a swing phase control device of the kind described at the outset which enables a natural course of motion and which is in particular suited for different fast courses of motion.
By providing the second throttle different controls for flexing and stretching the knee joint are possible. The course of motion looks more natural. The throttle is adjusted so that it is suited for slow and medium fast motions. However, if the person moves very fast the piston moves into the cylinder with a high speed and compresses the fluid within the second chamber. The second throttle is closed after the pressure of the fluid within the second chamber exceeded the predetermined value. The fluid can not penetrate through the second throttle. Hence, the pressure within the second chamber rises more steeply and causes a dynamic pushback of the piston within the cylinder in the manner of a pneumatic spring. The knee joint is stretched in a fast and swinging manner. The swing phase control device according to the invention therefore provides for swinging and fast walking with the prosthesis.
Preferred embodiments of the inventive swing phase control device are defined in the dependent claims.
Further features and advantages of the inventive swing phase control device will arise from the description of an embodiment with reference to the accompanying FIGURE. The accompanying FIGURE shows a sectional view of an embodiment of the swing phase control device.
The swing phase control device 1 comprises a piston and cylinder arrangement 2 having a cylinder 3 and a piston 12. The cylinder 3 comprises a tubular portion 5 having a cap member 4 at one end thereof and a base member 6 at the opposite end.
The cap member 4 comprises an inlet port 7 forming a connection between the ambient air and a first inlet side chamber 8 formed within the cylinder 3. The inlet port 7 is provided with a check valve 9. The check valve 9 is formed as a flutter valve opening towards the first chamber 8. A bore 10 is provided in a sleeve within the cap member 4 coaxially to the cylinder 3. The bore 10 houses a friction bearing for a piston rod 11 which is connected to the piston 12 of the piston and cylinder arrangement 2. The outer side of the inlet port 7 is covered by a filter 13 for protection against entrance of undesired components from the ambient air. An annular seal 14 is provided between the coaxial port 10 and the piston rod 11 for sealing the space.
The cap member 4 is screwed onto the tubular portion 5. An annular seal 15 seals the connection between the tubular portion 5 and the cap member 4. The tubular portion 5 is screwed onto the base member 6. An annular seal 16 is provided between the tubular portion 5 and the base member 6 for sealing.
A second chamber 17 is formed within the tubular portion 5 at the side of the piston 12 opposite to the first chamber 8. The second chamber is defined by the base member 6 on the side opposite to the piston 12.
A bore 18 opening into the second chamber 17 is coaxially provided within the base member 6. The base member 6 comprises a radial outle
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Olhydraulik Und Pneumatik, vol. 8, No. 9, pp. 352-357.
Biedermann Motech GmbH
Brown Donald
Neuner George W.
Willse David H.
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