Segmented Circumferential Trocar Seal Assembly
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Solution Overview
Problem
Current trocar assemblies face issues with seal durability and increased resistance when using large diameter instruments due to hoop stress and material strain, particularly with lip seals that are prone to tearing and increased normal force.
Innovation Solution
A seal assembly composed of multiple overlapping seal segments with angled edges and interlocking layers, reducing hoop stress and providing a secure seal around the instrument shaft, which can be used as a single or dual sealing system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lip seal with a small hole is used to seal around instruments of various diameters, then the seal can accommodate a full range of instruments, but the seal is subjected to 400% strain and experiences increased normal force causing drag and resistance
Solution Approach 1:
The seal is divided into multiple segments (typically three) that can independently deflect and accommodate instruments of different diameters. Each segment acts as an independent sealing element, allowing the seal to adapt to various instrument sizes without requiring the entire seal to stretch uniformly, thereby reducing strain and normal force.
Solution Approach 2:
The seal segments are arranged in a circumferential pattern around the opening, creating a multi-dimensional sealing structure. This circumferential arrangement allows the seal to accommodate instruments of various diameters by deflecting segments radially outward, rather than requiring uniform circumferential stretching, thus reducing the 400% strain experienced by traditional lip seals.
2Adaptability or versatility
If a lip seal is stretched to accommodate large diameter instruments, then the seal must provide adequate sealing, but the seal material is prone to ripping and tearing under high strain
Solution Approach 1:
Dividing the seal into multiple segments distributes the mechanical strain across separate elements rather than concentrating it in a single continuous seal. This segmentation prevents the seal material from experiencing uniform high strain that leads to ripping and tearing, thereby improving reliability when accommodating large diameter instruments.
Solution Approach 2:
The seal segments are designed with specific material properties and geometric parameters (such as thickness, curvature, and deflection capacity) that allow them to accommodate large diameter instruments without exceeding the material's elastic limit, preventing ripping and tearing while maintaining sealing integrity.
3Device complexity
If a single sealing mechanism is used, then the overall complexity of the trocar is reduced, but the seal must provide sealing both when instruments are present and when they are removed
Solution Approach 1:
The seal segments are designed to dynamically adapt their configuration based on the presence or absence of an instrument. When an instrument is inserted, the segments deflect radially outward to accommodate it; when the instrument is removed, the segments return to their original position to seal the opening, providing dual functionality with a single sealing mechanism.
Solution Approach 2:
The seal segments are constructed as flexible elements that can bend and deflect to accommodate instruments of various sizes while maintaining sealing contact. This flexibility allows a single sealing mechanism to effectively seal both when instruments are present and when the opening needs to be closed, eliminating the need for separate sealing systems.
4Reliability
If the opening diameter of the seal is made small relative to the largest diameter instruments, then the seal can provide adequate sealing, but the normal force upon the instrument shaft increases significantly
Solution Approach 1:
The segmentation of the seal allows the opening to be smaller relative to large instruments while distributing the normal force across multiple separate segments rather than concentrating it in a single continuous seal. This reduces the overall normal force on the instrument shaft while maintaining effective sealing through the distributed contact points of the segments.
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 solution effectively minimizes leakage and reduces the likelihood of seal tearing, providing improved resistance to instrument insertion and retraction while maintaining a secure seal without increased normal force, thus enhancing the usability of trocar assemblies with various instrument diameters.
Implementation Method 1
The solution effectively minimizes leakage and reduces the likelihood of seal tearing, providing improved resistance to instrument insertion and retraction while maintaining a secure seal without increased normal force
Implementation Method 2
providing improved resistance to instrument insertion and retraction while maintaining a secure seal without increased normal force
Data Source
AI summary
A seal assembly adapted for use in conjunction with a trocar assembly includes a plurality of seal segments. Each seal segment includes a peripheral edge and a seam edge. At least a first seal segment and a second seal segment are connected along their respective peripheral edges to form a first seal layer having a seam defined by the seam edge of the first seal segment and the seam edge of the second seal segment. At least a third seal segment and a fourth seal segment are connected along their respective peripheral edges to form a second seal layer having a seam defined by the seam edge of the third seal segment and the seam edge of the fourth seal segment. The seam of the first seal layer has a first longitudinal axis and the seam of the second seal layer has a second longitudinal axis, and the first seal layer is oriented relative to the second seal layer such that the first longitudinal axis is angularly oriented relative to the second longitudinal axis.