Prosthetic Knee Valve Using Hydraulic Friction for Sensorless Damping
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Solution Overview
Problem
Prosthetic knee joints with complex and expensive double sensor systems for controlling damping during different phases of a step cycle, which can lead to unwieldy and heavy constructions due to the need for electrical power or structural complexity.
Innovation Solution
A valve design where the inlet is arranged to exert a total force perpendicular to the displacement direction when the valve is in the first position, creating increased friction and eliminating the need for a knee extension sensor, allowing fluid flow only through a throttle outlet and a one-way valve connection between extension and flexion chambers, and using a switching pin and spring mechanism to control the valve's position based on pressure and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual sensors are used to detect knee extension and forefoot load, then damping control accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the functions of knee extension detection and forefoot load detection into a single sensor system. The sensor detects both the angular position of the knee joint and the force applied to the forefoot, eliminating the need for separate sensors and reducing overall system complexity while maintaining measurement accuracy for damping control
Solution Approach 2:
The sensor system is designed to perform multiple functions: detecting knee extension angle, detecting forefoot load, and providing this information to the control unit for damping adjustment. This multi-functional approach replaces what would traditionally require multiple specialized sensors, reducing device complexity
2Measurement precision
If electrical power is provided to sensors, then measurement precision is improved, but weight and size of the knee structure increase
Solution Approach 1:
The sensor system is designed to operate without external electrical power by utilizing the mechanical energy already present in the knee joint's movement and load-bearing operations. The sensor self-generates or self-regulates its operation based on the mechanical inputs, eliminating the need for batteries, wires, or power management components that would add weight
3Force
If valve blockage is complete, then damping resistance is improved, but fluid flow control flexibility is reduced
Solution Approach 1:
The valve is designed with dynamic control capability, allowing it to adjust its opening degree continuously based on sensor feedback and control unit decisions. The valve can transition between fully closed (high damping resistance), partially open (moderate damping resistance), and fully open (low damping resistance) positions, providing flexible adaptation to different gait phases and loading conditions
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 design simplifies the prosthetic knee joint by eliminating the need for electronic sensors, reducing size and cost, while providing adjustable damping resistance for stable and safe walking by controlling fluid flow based on the prosthetic's state, ensuring increased resistance when the knee is not fully extended and reduced resistance during flexion.
Implementation Method 1
the fluid exerts a total force on the valve body, which also acts at least in a force direction that is perpendicular to the displacement direction when the valve body is in the first position
Implementation Method 2
EP 2 000 714 A2 describes a valve having a valve body movable within a valve housing, which can be displaced along a displacement direction. The valve is closed when the valve body is at one of the stops limiting the displacement and allows hydraulic fluid to flow only when the valve body is in a central position
Data Source
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AI summary
The invention relates to a valve (20) with an inlet (28), an outlet (30) connected to the inlet (28) by a fluid connection, and a valve body (26) which can be moved by displacement along a displacement direction into a first position in which the fluid connection is blocked and into a second position in which the fluid connection is open, wherein the inlet (28) is designed and arranged such that a fluid entering through the inlet (28) exerts a total force on the valve body (26) which acts at least also in a force direction perpendicular to the displacement direction when the valve body (26) is in the first position, wherein the valve (20) has a throttle outlet (32), and wherein the valve body (26) is designed and arranged such that fluid flowing in through the inlet (28) leaves the valve (20) at least also through the throttle outlet (32), regardless of the position of the valve body (26).