Surgical Instrument Cable Retention With an Enlarged Distal End
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Solution Overview
Problem
Existing surgical instruments face challenges in creating robust mechanical connections between components made from dissimilar materials, particularly under large forces, while maintaining a small size and low manufacturing costs, and ensuring reliable operation of joints with cable actuation.
Innovation Solution
The surgical instrument employs an enlarged distal end of a cable that is retained within a recess of an end effector body by a retaining member, using a polymer for the end effector body and a stronger metal or metal alloy for the retaining member, which provides mechanical support and ensures secure coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding or adhesive coupling methods are used to connect components made from dissimilar materials, then the mechanical connection strength is improved, but the manufacturing cost increases and the process becomes more complex
Solution Approach 1:
The patent replaces welding and adhesive coupling methods with a mechanical interference fit system. The cable features an enlarged distal end that fits into a recess in the end effector body, creating a secure mechanical connection without requiring welding equipment or adhesives. This resolves the contradiction by achieving strong mechanical connections through pure mechanical means, eliminating the need for expensive welding processes while maintaining connection strength.
Solution Approach 2:
The patent introduces an intermediary structure - the enlarged distal end of the cable that fits into the recess of the end effector body. This intermediary feature acts as a mechanical mediator between the cable and end effector, providing a robust connection point that avoids the need for direct welding or adhesive bonding between dissimilar materials, thereby reducing manufacturing complexity and cost.
2Reliability
If nuts and bolts or other mechanical retainers are used to connect components, then the mechanical connection reliability is improved, but the overall diameter of the surgical instrument increases
Solution Approach 1:
The patent applies the nesting principle by placing the enlarged distal end of the cable inside a recess in the end effector body. The cable's enlarged end is nested within the recess space, and the retaining member is nested around the cable assembly. This nested configuration provides reliable mechanical retention without adding external protrusions, thereby maintaining the compact overall diameter of the surgical instrument.
Solution Approach 2:
The patent transitions from external mechanical retainers (nuts and bolts that would increase diameter) to an internal interference fit system. The connection is achieved in the radial dimension through the enlarged distal end fitting into the recess, with the retaining member providing axial retention. This dimensional reconfiguration maintains the instrument's compact external profile while ensuring reliable mechanical connections.
3Manufacturing precision
If laser welding equipment is used to couple components, then the manufacturing precision is improved, but the manufacturing cost increases due to expensive tooling and equipment
Solution Approach 1:
The patent replaces laser welding equipment with a mechanical interference fit system that can be manufactured using standard precision machining or molding processes. The enlarged distal end of the cable and the corresponding recess in the end effector body are formed through conventional manufacturing methods, eliminating the need for expensive laser welding tooling while maintaining adequate manufacturing precision for reliable assembly.
4Strength
If hardware solutions such as nuts and bolts are used for mechanical connections, then the mechanical connection strength is improved, but the device complexity increases and space requirements increase
Solution Approach 1:
The patent merges multiple functions into the cable assembly itself. The cable's enlarged distal end serves both as the structural element that transmits force and as the mechanical retention feature that connects to the end effector body. The retaining member is integrated around this enlarged end, combining the functions of connection and retention in a single integrated assembly, thereby reducing overall device complexity compared to separate nuts, bolts, and retaining features.
Data Source
AI summary
A method of assembling a surgical instrument comprising an end effector body and a retaining member includes inserting a distal end feature of a cable within a recess in the end effector body, the distal end feature extending radially outwardly from the cable. The method further includes positioning a retaining member over the recess in the end effector body to retain the distal end feature of the cable within the retaining member.