Planetary Gear Assembly for Variable Speed Tissue Resection
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Solution Overview
Problem
Conventional surgical instruments for cutting tissue often lack the ability to efficiently adjust rotational speed, which can limit their effectiveness in tissue resection procedures.
Innovation Solution
A reciprocating rotary surgical instrument equipped with a planetary gear assembly that allows for the increase or decrease of rotational speed, enabling the elongated inner member to rotate at varying speeds relative to the rotary driver, thereby enhancing cutting and detaching capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional rotary driver is used to rotate the inner member at the same speed, then the device structure is simple, but the rotational speed cannot be adjusted to improve cutting effectiveness
Solution Approach 1:
A planetary gear assembly is introduced as an intermediary mechanism between the rotary driver and the inner member. This gear assembly includes sun gears, planet gears, and ring gears that transmit and modify rotational motion, enabling speed adjustment while maintaining a relatively compact structure suitable for endoscopic applications
Solution Approach 2:
The system transitions from a fixed-speed rotation to a variable-speed rotation mechanism. The planetary gear assembly allows the inner member to rotate at different speeds relative to the rotary driver, providing dynamic speed adjustment capability that enhances tissue cutting effectiveness
2Ease of operation
If the inner member rotates at the same speed as the rotary driver, then the mechanism is straightforward, but the cutting and detaching capabilities are limited
Solution Approach 1:
The planetary gear assembly serves as a mechanical intermediary that modifies the rotational speed transmitted from the rotary driver to the inner member. This allows the inner member to rotate faster or slower than the driver, improving cutting performance without requiring a completely new drive mechanism
Solution Approach 2:
The planetary gear assembly is nested within the handpiece structure, with sun gears, planet gears, and ring gears arranged in a compact configuration. This nested arrangement allows the speed modification mechanism to be integrated into the existing device footprint without significantly increasing overall 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
The planetary gear assembly enables the elongated inner member to rotate at increased or decreased speeds, improving the efficiency and effectiveness of tissue cutting and detachment during surgical procedures.
Implementation Method 1
The planetary gear assembly includes a fixed ring gear, one or more planet gears, and a sun gear. The fixed ring gear meshes with the planet gears, which in turn mesh with the sun gear.
Implementation Method 2
The planetary gear assembly is configured to increase or decrease rotational speed, enabling the elongated inner member to rotate at an increased or decreased speed relative to the rotary speed of the rotary driver.
Implementation Method 3
The translation piece is disposed in a groove of the helical member such that the rotary driving of the drive assembly results in the helical member moving linearly in the first direction, switching directions, moving linearly back in the second direction, switching directions back to the first direction, etc.
Data Source
AI summary
An endoscopic tissue resecting system that includes a reciprocating rotary surgical instrument for cutting tissue that includes a planetary gear assembly to vary rotational speed. A method of cutting and detaching tissue includes positioning an outer member such that tissue is located within a window in the outer member, engaging the tissue with an inner member, and simultaneously rotating at an increased speed relative to a rotary driver and translating the inner member to cut the tissue. A tangential cutting force is applied to the tissue with the inner member to mechanically cut and detach the tissue.