Stent Delivery Speed Change Mechanism
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Solution Overview
Problem
Existing stent delivery systems face challenges in accurately and promptly releasing stents within lumens of the body, as they often require manual precision and speed control to ensure proper placement and expansion.
Innovation Solution
A stent delivery system incorporating a speed change mechanism with a rotary body and a displacement body, featuring gears with varying diameters to adjust the moving speed of the outer tube relative to the inner tube, allowing for high-speed release proximity and low-speed precise positioning of the stent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the outer tube and gear rack are moved quickly to reach the stent vicinity, then the release time is reduced, but the positioning accuracy deteriorates
Solution Approach 1:
The operating mechanism dynamically adjusts the moving speed of the outer tube through a speed change mechanism. A wheel with variable diameter (larger at proximal end, smaller at distal end) engages with the gear rack, causing the tube to move faster during initial approach and slower during final positioning. This dynamic speed adjustment resolves the contradiction by enabling both rapid deployment and precise stent placement.
2Device complexity
If a gear rack with constant diameter is used, then the structure is simple, but the speed control precision is insufficient
Solution Approach 1:
The wheel component is designed with asymmetric diameter variation along its axial length. The proximal portion has a larger diameter while the distal portion has a smaller diameter, creating an asymmetric gear engagement profile. This asymmetry enables differential speed control - faster movement when engaging the larger diameter portion and slower movement when engaging the smaller diameter portion - thereby achieving precise speed control without excessive structural complexity.
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
Enables prompt and accurate stent release and indwelling by adjusting the speed of the outer tube's movement, ensuring precise placement and preventing positional deviation during stent expansion within the lumen.
Implementation Method 1
a gear rack is meshed with a gear of a rotatable wheel, and the outer tube is configured to be connected to an end portion of the gear rack. With the wheel rotated in a predetermined direction, the gear rack is advanced and retracted in the axial direction
Implementation Method 2
a speed change mechanism which is provided between the rotary body and the displacement body and changes the speed of the rotation of the rotary body, thereby changing the moving speed of the displacement body by transmitting the rotation to the displacement body
Data Source
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AI summary
An operating unit (18) constituting a stent delivery system (10) is provided with a first rotary roller (40) having a first gear (38) and a second rotary roller (44) having a second gear (42). The first gear (38) is meshed with a first tooth portion (56) of a rack member (36) and the second gear (42) is meshed with a second tooth portion (58) of the rack member (36). The first gear (38) is formed to have a large diameter relative to the second gear (42) and at the time of releasing a stent (16), after positioning a distal end of an outer tube body (14) close to the stent (16) through the rack member (36) with the rotation of the first rotary roller (40) of the operating unit (18), it is possible to move the outer tube body (14) toward a proximal side at a lower speed than that in the previous state with the rotation of the second rotary roller (44).