Hydrostatic Bearing Valve for Sensorless Prosthetic Knee Damping
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Solution Overview
Problem
Conventional prosthetic knee joints with dual sensor technology are complex, prone to errors, costly, and often require electrical energy, making them large, cumbersome, and heavy, as they struggle to accurately control damping during different phases of the gait cycle, particularly failing to distinguish between heel impact and incline loading.
Innovation Solution
A valve design where the inlet fluid exerts a total force perpendicular to the displacement direction, creating a hydrostatic bearing that increases friction and counteracts displacement, allowing for a prosthetic knee joint to be controlled without electronic components by using a fluid connection between extension and flexion chambers with a one-way valve and a throttle outlet, enabling adjustable flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual sensor technology is used to control damping during different phases of gait cycle, then damping control accuracy is improved, but device complexity increases and requires electrical energy making the system large and heavy
Solution Approach 1:
The patent replaces electronic sensors and electrical control systems with a purely mechanical valve system. The valve body uses geometric design where fluid pressure automatically positions the valve body to control damping, eliminating the need for electronic sensors, processors, and power sources while maintaining accurate phase-dependent damping control.
Solution Approach 2:
The valve system is self-regulating through its geometric design. The valve body automatically positions itself based on fluid pressure directions during different gait phases, requiring no external control signals, sensors, or power sources. The system serves itself by using the inherent physics of fluid flow to achieve the desired damping control.
2Measurement precision
If dual sensor technology is used to detect knee extension and forefoot load, then gait phase detection accuracy is improved, but weight and size of the prosthetic knee joint increase
Solution Approach 1:
The patent eliminates electronic sensors and replaces them with a mechanical valve system that detects gait phase through fluid pressure. The valve body's geometric design automatically responds to pressure changes during different gait phases, providing accurate detection without adding weight from batteries, sensors, or electronic components.
Solution Approach 2:
The patent uses hydraulic fluid pressure to detect and respond to gait phase changes. The fluid pressure acts on the valve body in specific directions during different phases, automatically controlling damping without electronic detection systems. This hydraulic approach replaces heavy electronic sensors with a lightweight fluid-based detection mechanism.
3Ease of operation
If conventional valve design is used where fluid force acts parallel to displacement direction, then valve operation simplicity is maintained, but hydrostatic bearing effect and friction are reduced
Solution Approach 1:
The patent introduces asymmetry in the valve design by angling the inlet relative to the valve body displacement direction. This creates asymmetric fluid pressure distribution that generates a perpendicular hydrostatic bearing force, increasing friction to prevent unwanted valve movement while maintaining controlled operation through the switch mechanism.
Solution Approach 2:
The hydrostatic bearing effect created by the angled inlet pre-positions the valve body by increasing friction before actual valve switching occurs. This preliminary frictional force ensures the valve remains stable in its current position until a deliberate switching action is taken, preventing accidental or premature valve operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration eliminates the need for sensors, reduces system size and cost, and provides stable, secure control by ensuring the valve remains closed until the knee is almost fully extended, allowing for controlled movement and adjustable damping based on fluid pressure.
Implementation Method 1
an inlet of the valve (28) which is designed and arranged such that a fluid entering through the inlet (28) exerts a total force on the valve body (26) that at least also acts in a force direction which is perpendicular to the displacement direction
Implementation Method 2
a valve body (26) which can be brought into a first position, in which the fluid connection (22) is blocked, by displacing it in a displacement direction
Implementation Method 3
The passage is preferably equipped with a one-way valve to prevent a return flow of the fluid from the flexion chamber into the extension chamber
Implementation Method 4
creating a hydrostatic bearing that increases friction and counteracts displacement
Data Source
AI summary
A valve with an inlet, an outlet that is connected to the inlet via a fluid connection, and a valve body which can be brought by displacing it along a displacement direction into a first position, in which the fluid connection is blocked, and a second position, in which the fluid connection is open, wherein the inlet is designed and arranged in such a way that a fluid entering through the inlet exerts a total force on the valve body that at least also acts in a force direction which is perpendicular to the displacement direction when the valve body is in the first position.