Flexible Endoscope Shaft Torsion Wire Actuation
Solution Overview
Problem
Existing flexible endoscope and endoscopic instrument shafts face challenges with controllability due to cable pull systems, which require frequent retensioning, lead to shaft shortening, and are prone to breakage, especially in small diameters, and have high design and maintenance efforts.
Innovation Solution
A shaft design featuring a first and second shank section where the second section is actively bendable, utilizing a traction means with a cord drive for longitudinal adjustment, allowing for precise angling without the need for cable tensioning, and incorporating a torsion shaft for actuation, enabling direct control of the bendable section through a handle with a motor or handwheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cable pulls are used to enable controllable angling of the shaft section, then the shaft can be actively bent in desired directions, but the cables become longer after repeated use requiring frequent retensioning
Solution Approach 1:
The patent extracts the problematic cable pull system and replaces it with a torsion wire mechanism. The torsion wire is integrated into the shaft structure itself, eliminating the need for separate cable pulls that require retensioning. This extraction of the core angling function and its reimplementation with a more reliable mechanism directly addresses the reliability issue while maintaining controllability.
Solution Approach 2:
The patent changes the fundamental parameter of the actuation mechanism from cable tension to torsion wire rotation. By using the torsion coefficient of the wire and rotational movement instead of linear cable tension, the system achieves stable, repeatable angling control without the lengthening and retensioning problems inherent in cable pull systems.
2Ease of operation
If cable pulls are used for shaft angling control, then the shaft can be positioned, but the necessary permanent tension leads to shaft shortening
Solution Approach 1:
The patent substitutes the cable pull mechanical system with a torsion wire-based system. Instead of using tensioned cables that physically shorten the shaft when under permanent tension, the torsion wire system uses rotational deformation of the wire itself, which does not affect the overall shaft length. This mechanical substitution resolves the contradiction between positioning capability and shaft length maintenance.
3Ease of operation
If cable pulls are used to control shaft angling, then the shaft can be steered, but curvatures cause increased friction making operation more difficult
Solution Approach 1:
The patent merges the angling control function directly into the shaft structure by integrating the torsion wire within the shaft itself. This integration eliminates the need for separate cable pulls that run through curved paths and experience friction. The torsion wire is positioned to work with the shaft's natural curvature, combining the structural elements to reduce friction and improve ease of operation.
4Ease of operation
If cable pulls are used for shaft control, then the shaft can be actuated, but the cables can break due to friction and wear
Solution Approach 1:
The patent extracts the vulnerable cable pull elements from the system and replaces them with an integrated torsion wire mechanism. The torsion wire is protected within the shaft structure and does not experience the same friction and wear conditions as external cable pulls. This extraction and replacement directly addresses the durability and reliability issues while maintaining full actuation capability.
5Reliability
If adjustment devices are added to retension cable pulls, then cable tension can be maintained, but design and operating effort increase
Solution Approach 1:
The patent implements a self-service mechanism where the torsion wire automatically maintains its functional properties through its inherent torsional characteristics. The system does not require external adjustment devices because the torsion wire naturally resists permanent deformation and maintains its elastic properties. This self-service approach eliminates the complexity of adjustment devices while ensuring reliable tension maintenance.
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 provides a durable, robust, and simple-to-produce shaft with improved controllability, independent of shaft curvature, allowing precise bending in various directions without the need for frequent retensioning, and is suitable for small diameters, reducing maintenance and operational effort.
Implementation Method 1
at least one torsion shaft is arranged inside the first shaft section through which an operating movement generated by actuating means can be transmitted
Implementation Method 2
A cord drive, also referred to as a twist drive, includes a plurality of cords or wires that are twisted together
Data Source
Figure 1a~1b
Figure 2~3
Figure 4
AI summary
A shaft for a flexible endoscope or a flexible endoscopic instrument comprises a first shaft section (4) and a second shaft section (5) arranged distal to the first, wherein the second shaft section (5) is angular relative to a distal end region of the first shaft section (4) by longitudinal adjustment of at least one traction element running within the second shaft section (5), and wherein at least one cord drive is provided for longitudinal adjustment of the traction element. This creates a shaft for a flexible endoscope or a flexible endoscopic instrument that is simple in design, robust, and inexpensive to manufacture. The invention also relates to a flexible endoscope and a flexible endoscopic instrument.