Clamp Arm Hinge Coupling With Integrated Pivot Boss Alignment

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Solution Overview

Problem

Existing ultrasonic surgical instruments face challenges in simplifying assembly processes and reducing component count while maintaining mechanical strength and dimensional accuracy, particularly in the coupling of clamp arm assemblies with shaft assemblies, which can lead to misalignment issues due to material warpage during manufacturing.

Innovation Solution

The integration of pivot bosses or flexible pivot bosses on the clamp arm assemblies, which are monolithically formed with the shaft assemblies, allows for a snap-fit engagement without the need for separate pins, using materials like plastic to reduce manufacturing costs and prevent misalignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If separate pins are used to couple clamp arm assemblies with shaft assemblies, then mechanical strength is improved, but device complexity and assembly difficulty increase

Engineering Contradiction:

Improvemechanical strengthVSAvoiddevice complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The pivot boss is integrally formed with the shaft assembly as a single monolithic structure, eliminating the need for separate coupling pins. This merging of components maintains mechanical strength through the integral connection while reducing device complexity by removing discrete fastening elements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The clamp arm assembly features a receptacle that self-aligns with the pivot boss through snap-fit engagement. The geometry of the receptacle and pivot boss are designed to automatically guide proper alignment during assembly, eliminating the need for separate alignment procedures or additional fastening components.

Inventive Principle:

Principle #25Self-service

2Strength

If separate pins are used for coupling, then mechanical integrity is improved, but assembly time and manufacturing cost increase

Engineering Contradiction:

Improvemechanical integrityVSAvoidassembly time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

By integrating the pivot boss directly into the shaft assembly as a monolithic structure, the number of assembly steps is reduced. The snap-fit engagement allows for rapid assembly without requiring separate pin insertion, securing, or alignment procedures, thereby reducing assembly time while maintaining mechanical integrity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The pivot boss is pre-formed as an integral part of the shaft assembly during manufacturing. This preliminary formation eliminates the need for post-assembly operations such as pin insertion and fastening, allowing for quick assembly while ensuring mechanical integrity is maintained through the integral design.

Inventive Principle:

Principle #10Preliminary action

3Strength

If traditional coupling methods are used, then mechanical strength is improved, but misalignment issues occur due to material warpage

Engineering Contradiction:

Improvemechanical strengthVSAvoiddimensional accuracy

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The integral formation of the pivot boss with the shaft assembly eliminates interfaces between separate components that could be affected by material warpage. As a monolithic structure, the pivot boss maintains precise dimensional relationships with the shaft assembly, preventing misalignment issues while preserving mechanical strength.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The receptacle geometry acts as an intermediary that compensates for any minor dimensional variations. The snap-fit engagement design includes geometric features that guide and constrain the clamp arm assembly into proper alignment, ensuring precise positioning despite potential material warpage during manufacturing.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This design simplifies assembly, reduces component count, and maintains mechanical integrity, ensuring precise alignment and functionality of the clamp arm with the ultrasonic blade for efficient tissue cutting and sealing.

Implementation Method 1

The receptacle is configured to securely and pivotally retain the pivot boss, allowing the clamp arm assembly to pivot relative to the shaft assembly

Methodology Applied

Scientific EffectSnap-fit engagement: Mechanical Fastener

Implementation Method 2

The flexible pivot boss is configured to flex to facilitate insertion of the flexible pivot boss between the side members, and to resiliently extend to engage within the receptacle

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4572689B1Surgical instrument with clamp arm and pivot shaft hinge coupling

Publication Date: 2026.04.01 CILAG GMBH INTERNATIONAL

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AI summary

A surgical instniment includes a body, a shaft assembly, an ultrasonic blade, and a clamp arm assembly. The shaft assembly extends distally from the body and includes an outer sheath and a first pivot portion such that the outer sheath and the first pivot portion are integrally formed together with each other as a first unitary piece. The clamp arm assembly includes a clamp arm and a second pivot portion such that the clamp arm and the second pivot portion are integrally formed together with each other as a second unitary piece. The clamp arm assembly is pivotally coupled to the shaft assembly via the first and second pivot portions.