Nested Surgical Shaft Assembly for Compact Multi-Component Stability

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Solution Overview

Problem

Assembling surgical instruments with multiple components within a small diameter presents challenges in terms of time efficiency, cost efficiency, and mechanical stability, particularly in electrosurgical instruments that need to accommodate wires and flex circuits while minimizing manufacturing tolerances and preventing buckling.

Innovation Solution

A nested shaft assembly arrangement is implemented, where internal components like the inner guide, closure beam, and knife assembly are carefully nested within an outer shaft, with transverse motion during assembly to minimize gaps and ensure structural integrity, reducing the risk of buckling and facilitating efficient assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple components are included within a small diameter shaft assembly, then the instrument can perform multiple functions and accommodate wires and flex circuits, but the assembly time increases and manufacturing tolerances become more difficult to mitigate

Engineering Contradiction:

Improvefunctional capabilityVSAvoidassembly time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements a nested shaft assembly arrangement where an inner shaft is positioned within an outer shaft, and additional components are nested within the inner shaft. This nesting configuration allows multiple functional components to be accommodated within a compact diameter while simplifying the assembly process through sequential insertion, thereby resolving the contradiction between functional versatility and assembly time.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If multiple components are included within a small diameter shaft assembly, then the instrument can perform multiple functions, but the manufacturing precision requirements increase and cost efficiency decreases

Engineering Contradiction:

Improvefunctional capabilityVSAvoidtolerance control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The nested shaft assembly arrangement allows components to be positioned sequentially within each other, which simplifies the control of manufacturing tolerances compared to traditional side-by-side configurations. The nesting structure inherently provides alignment references that reduce the precision requirements for each individual component, thereby enabling multiple functions while maintaining reasonable manufacturing precision and cost efficiency.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Adaptability or versatility

If multiple components are included within a small diameter shaft assembly, then the instrument can perform multiple functions, but the mechanical stability decreases and buckling risk increases

Engineering Contradiction:

Improvefunctional capabilityVSAvoidmechanical stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The nested shaft assembly arrangement provides structural support through the concentric configuration of inner and outer shafts, which enhances mechanical stability compared to dispersed component layouts. The nesting structure creates a more rigid overall assembly that resists buckling while still accommodating multiple functional components within the confined space.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent utilizes the radial dimension by positioning components at different radial distances from the central axis, with the inner shaft nested within the outer shaft. This dimensional arrangement allows multiple components to be distributed in three-dimensional space rather than competing for linear space, thereby maintaining mechanical stability while achieving functional versatility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Ease of manufacture

If traditional assembly methods are used for multiple shaft components, then assembly is straightforward, but the assembly time increases and efficiency decreases

Engineering Contradiction:

Improveassembly simplicityVSAvoidassembly efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The nested shaft assembly arrangement simplifies the assembly process by enabling sequential insertion of components in a logical order (outer shaft first, then inner shaft, then additional components). This systematic nesting approach makes the assembly process more straightforward and efficient compared to traditional methods that may require complex alignment procedures, thereby improving productivity while maintaining ease of manufacture.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS20260047880A1Medical instrument shaft assembly with nested components

Publication Date: 2026.02.19 CILAG GMBH INTERNATIONAL

AI summary

An apparatus includes a body, a shaft assembly, and an end effector. The shaft assembly includes an outer shaft and two elongate members. A first portion of the first elongate member is positioned within a recess of the second elongate member, while a second portion of the first elongate member is laterally offset relative to the second elongate member. A first portion of the second elongate member is positioned within a recess of the first elongate member, while a second portion of the second elongate member is laterally offset relative to the first elongate member. The end effector includes a first component coupled with the first elongate member and a second a second component coupled with the second elongate member, such that the first and second elongate members are operable to drive movement of the respective first and second components of the end effector.