Non-Circular Pulley Profile for Endoscope Bending Control
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Solution Overview
Problem
Existing endoscope bending control mechanisms face challenges in reducing bending-operational force while maintaining durability and simplicity, often leading to increased complexity, manufacturing costs, and potential fatigue in wires due to pulley diameter reduction or the addition of power-assisted motors.
Innovation Solution
A bending control mechanism featuring a pulley with a non-circular profile, including a small-radius section, a large-radius section, and a varying-radius section, where the wire is wound onto the large-radius section at initial bending stages and shifted to the small-radius section at maximum bending, reducing operational force and fatigue without adding complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the diameter of the pulley is reduced to decrease bending-operational force, then the bending-operational force is reduced, but the wire experiences fatigue and breaks due to repeated extension and bending at a small radius of curvature
Solution Approach 1:
The pulley is segmented into multiple sections with different radii of curvature along its circumference. The wire winding path is divided into a first section with a first radius of curvature and a second section with a second radius of curvature, allowing the wire to experience different bending conditions at different stages of the bending operation.
Solution Approach 2:
Different sections of the pulley are given different local geometric properties. The first section has a larger radius of curvature to reduce stress during initial winding, while the second section has a smaller radius of curvature to reduce operational force during maximum bending. This local differentiation optimizes both wire durability and operational ease.
2Force
If links or a power-assisted motor are added to reduce bending-operational force, then the bending-operational force is reduced, but the component configuration becomes complex, increasing manufacturing costs and control body size
Solution Approach 1:
The pulley's non-circular geometry automatically provides the force-reducing function through its shape alone, without requiring external power assistance or complex mechanical linkages. The varying radius of curvature self-regulates the wire tension and bending force throughout the operation cycle.
Solution Approach 2:
The pulley's geometric parameter (radius of curvature) is changed along its circumference rather than maintaining a constant radius. This parameter variation along the pulley's perimeter allows the system to achieve force reduction through pure geometry, eliminating the need for additional active components.
3Force
If the diameter of the pulley is reduced to decrease bending-operational force, then the bending-operational force is reduced, but the rotational angle of the pulley increases per unit amount of winding, increasing the operational movement amount and causing operator fatigue
Solution Approach 1:
The pulley transitions from a static constant-radius geometry to a dynamic varying-radius geometry that adapts to different operational stages. As the wire winds onto different sections of the pulley, the effective radius changes dynamically, optimizing both force and rotational characteristics throughout the bending cycle.
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 configuration enhances operability and durability by optimizing the pulley profile, reducing the risk of wire fatigue and maintaining a compact, lightweight control body, while minimizing manufacturing costs and operational effort.
Implementation Method 1
A bending control mechanism for an endoscope according to the present invention provides a simple configuration and achieves a decreased amount of bending-operational force with superior operability. An outer peripheral profile of the pulley includes a non-circular section including a small-radius section having a small radius from a rotational center axis of the pulley, and a large-radius section having a radius from the rotational center axis that is larger than the small radius. The wire is wound onto the large-radius section at an initial winding stage at which the bendable section is at a non-bending position, and is wound onto the small-radius section at a stage where the bendable section is bent by a maximum amount.
Data Source
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AI summary
A bending control mechanism for an endoscope, provided with a control body and a bendable section including an insertion section, the bending control mechanism includes a pulley which is rotatably provided in the control body, and a wire connected between the pulley and the bendable section. An outer peripheral profile of the pulley, onto which the wire is wound, includes a non-circular section including a small-radius section having a small radius from a rotational axis of the pulley, and a large-radius section having a radius from the rotational axis that is larger than the small radius. The wire is wound onto the large-radius section at an initial winding stage at which the bendable section is at a non-bending position. The wire is wound onto the small-radius section at a stage where the bendable section is bent by a maximum amount.