Lever Stack Mechanical Converter for Lithotripsy Stroke
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Solution Overview
Problem
Conventional ultrasonic lithotripsy devices face limitations in translational movement due to the limited stroke length provided by piezoelectric stacks, which restricts their effectiveness in procedures like pulverizing kidney stones, and are often dependent on specific resonant frequencies, making them complex and costly.
Innovation Solution
A mechanical converter assembly with a lever stack that translates a received drive force into a mechanical output force, providing a greater stroke length at the expense of force magnitude, allowing for increased translational movement without reliance on specific resonant frequencies, and offering a modular approach for adapting to different shaft configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a piezoelectric stack is used to drive the lithotripsy shaft, then the device can generate ultrasonic vibrations, but the stroke length is limited and the device becomes complex and costly due to resonance frequency requirements
Solution Approach 1:
The drive system is divided into two independent parts: a compact piezoelectric stack that generates high-frequency vibrations, and a separate mechanical converter assembly with levers that provides the required stroke length. This segmentation allows each component to be optimized independently, eliminating the need for a single complex resonant system.
Solution Approach 2:
A mechanical converter assembly acting as an intermediary between the piezoelectric stack and the lithotripsy shaft. This intermediary translates the small-amplitude high-frequency vibrations from the piezoelectric stack into larger stroke movements while maintaining operational simplicity and reducing overall system complexity.
2Length of moving object
If a longer stroke length is achieved through mechanical conversion, then translational movement is enhanced, but the force magnitude is reduced
Solution Approach 1:
The mechanical converter assembly changes the motion parameters by translating small-amplitude, high-frequency vibrations into larger-amplitude movements with longer stroke length. This parameter transformation allows the system to achieve the required stroke length while maintaining effective stone-breaking capability through the modified motion characteristics.
3Length of moving object
If multiple piezoelectric discs are stacked to increase dimensional change, then the translational movement increases, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the conventional approach of stacking multiple piezoelectric discs to achieve larger dimensional changes with a mechanical converter assembly. This substitution uses a simpler mechanical lever system instead of a complex multi-disc piezoelectric stack, reducing device complexity and cost while achieving the same translational movement effect.
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
The mechanical converter assembly enhances the stroke length of the lithotripsy shaft, enabling more efficient pulverization of kidney stones with reduced complexity and cost, and provides flexibility in energy application, suitable for various shaft designs and procedures.
Implementation Method 1
a lever stack including multiple levers that translate the received drive force into a mechanical output force
Implementation Method 2
a stack assembly of piezoelectric discs, such as 4 to 6 in number, with an approximately 15 to 20 millimeter outside diameter
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A mechanical converter assembly includes an input, a lever stack (multiple levers), and an output. The input is configured to receive a mechanical drive force (or mechanical input signal) from a driver resource. The lever stack translates the received drive force into a mechanical output force (or mechanical output signal). The output of the mechanical converter assembly is configured to apply the mechanical output force produced by the lever stack to a driven element. In one embodiment, use of the lever stack in the mechanical converter assembly provides translational gain in which an amount of translational movement at the input of the mechanical converter assembly results in a substantially greater amount of corresponding translational movement at the output.