Knee Joint Structure with Adjustable Elastic Return Mechanism
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Solution Overview
Problem
Prior knee joint structures in prosthetic limbs often exceed a critical bending angle during fast walking, leading to abnormal gait and instability, and require inconvenient disassembly for elastic strength adjustment.
Innovation Solution
A knee joint structure featuring a position-returning bore with a piston, elastic body, and adjustment cap in the knee-joint head portion, along with a push-bar axle and transmission axle, allowing for controlled bending angle and adjustable elastic strength to support normal walking gait and reduce effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the position-returning device is arranged on the knee-joint body portion and the protrusion block is arranged on the connection rod, then the knee joint can return to original state through spring force, but the critical bending angle becomes too small (60°-80°) causing the knee joint to exceed the critical angle during fast walking and fail to return to straight state
Solution Approach 1:
The patent divides the position-returning device into separate components: the elastic body remains on the knee-joint body portion while the push bar is integrated with the connection rod. This segmentation allows independent optimization of each component's position and function, enabling the push bar to effectively transmit force during larger bending angles while maintaining the return function.
Solution Approach 2:
The patent introduces a dynamic adjustment mechanism where the push bar can be repositioned along the connection rod according to different walking conditions. This dynamic adaptability allows the critical bending angle to be adjusted for different walking speeds, ensuring the knee joint can properly return to the straight state during both normal and fast walking.
2Reliability
If the position-returning device is arranged on the knee-joint body portion, then the spring force can drive the knee joint to return to original state, but adjustment of elastic body strength requires removing the shank prosthesis causing inconvenience
Solution Approach 1:
The patent extracts the adjustment function from the main body structure and creates a dedicated adjustment mechanism. The adjustment hole and adjustment bolt are specifically designed for this purpose, allowing users to adjust the elastic body strength by simply operating these extraction components without disassembling the entire shank prosthesis.
Solution Approach 2:
The patent enables users to perform the adjustment themselves through the conveniently located adjustment hole and adjustment bolt. This self-service design eliminates the need for professional assistance or complex disassembly procedures, allowing users to independently adjust the elastic body strength according to their walking needs.
3Adaptability or versatility
If the push bar is operable to drive and move the piston through the transmission axle and curved plate mechanism, then the critical bending angle can be increased above maximum walking angle, but the structure becomes more complex
Solution Approach 1:
The patent makes the connection rod serve multiple functions: it acts as both a structural connector and as the carrier for the push bar mechanism. The curved plate is integrated into the existing joint structure, allowing these components to perform both their original functions and the new position-returning function, thereby reducing overall structural complexity.
Solution Approach 2:
The patent nests the position-returning components within the existing joint structure. The piston is housed within the knee-joint head portion, the push bar moves within the connection rod, and the curved plate is integrated with the joint body. This nesting arrangement minimizes the increase in device complexity by utilizing existing spatial volumes.
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
Enhances walking safety by maintaining a stable gait and allows for easy adjustment of elastic strength according to walking speed, preventing continuous bending and tipping.
Implementation Method 1
an elastic body having two ends respectively supported on the piston and the adjustment cap... when the knee joint bends, the push bar compresses the elastic body to accumulate a spring force
Implementation Method 2
the push bar compresses the elastic body to accumulate a spring force, so that the knee joint, when rotating in an opposite direction, is returned to an original state by the spring force of the elastic body
Data Source
AI summary
A knee joint structure includes a knee joint head portion, a knee-joint body portion, and at least one curved plate. The knee joint head portion includes a position-returning device made up of a piston, an elastic body, and an adjustment cap and a transmission axle. The transmission axle includes a push-bar axle, which is pivotally coupled to a push bar operable to drive and move the piston. The knee-joint body portion includes a connection rod pivotally connected to the knee joint head portion. The curved plate connects the transmission axle and the knee joint body portion.