Endoscopic Tool Tip Face Gearing for Jam-Free Jaw Rotation
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Solution Overview
Problem
Endoscopic surgical instruments face challenges in achieving a compact design while ensuring uniform rotation of the jaw part without tilting and maintaining jam-free power transmission, especially when the tool tip is angled, due to limitations in existing toothing mechanisms that often require spring preloading and are difficult to clean.
Innovation Solution
The design features radially tapering tooth flanks on the teeth of the actuating rod, with both outward and inward tapering, and flat and curved partial surfaces to prevent tilting and ensure smooth power transmission, eliminating the need for axial compensation mechanisms like springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring elements are used to ensure sufficient engagement of the toothing on the face of the sections of the actuating rod, then good engagement is achieved, but the design effort is very high and cleaning is difficult
Solution Approach 1:
The invention extracts and eliminates the spring element from the actuating rod mechanism. Instead of using a spring to bias the distal section towards engagement, the design relies on the inherent geometry of the radially outwardly tapering tooth flanks to maintain continuous contact between the toothing elements during rotation, even when the tool tip is angled.
Solution Approach 2:
The invention changes the geometric parameters of the tooth flanks by designing them with a radial outward taper. This parameter change allows the toothing to self-adjust and maintain engagement without requiring additional biasing forces from springs, thereby simplifying the design while ensuring reliable power transmission.
2Reliability
If spring elements are used to ensure sufficient engagement of the toothing on the face of the sections of the actuating rod, then good engagement is achieved, but cleaning accessibility is difficult due to undercuts
Solution Approach 1:
The spring element is completely removed from the mechanism. The undercut regions that would trap contaminants are eliminated by replacing the spring-based engagement system with a geometric engagement system based on radially outwardly tapering tooth flanks, making the entire mechanism accessible for cleaning.
3Adaptability or versatility
If the tool tip is angled relative to the longitudinal axis of the shank to cover the largest possible effective range, then the effective range is increased, but tilting of the mutual teeth of the face gears occurs
Solution Approach 1:
The tooth flanks are designed with a radial outward taper, changing their geometric parameters. This allows the toothing to accommodate angular misalignment between the tool tip and shank axis while maintaining stable tooth-to-tooth contact, preventing tilting even when the tool tip is angled to expand the effective range.
Solution Approach 2:
The radially outwardly tapering tooth flanks create a dynamic engagement system that automatically adjusts to angular deviations. As the tool tip angles relative to the shank, the taper geometry allows the teeth to maintain contact without rigid alignment requirements, enabling stable operation across a range of angles.
4Power
If conventional toothing mechanisms are used to allow rotation of the tool, then power transmission is achieved, but jamming occurs when the tool tip is angled
Solution Approach 1:
The critical parameter change is the radial outward taper of the tooth flanks. This geometry ensures that as the tool tip angles, the teeth maintain line contact along the tapered surface rather than point contact or edge contact, preventing jamming while continuously transmitting power during rotation.
Data Source
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AI summary
The invention relates to a medical instrument (1) with a hollow shaft (2), at the proximal end of which a handle (3) is arranged and at the distal end of which a tool (4) is arranged in such a way that a tool (4) carrying distal end area of the shank (2) is designed as a tool tip (6) that can be bent relative to the longitudinal axis (5) of the shank (2), and the tool (4) can be rotated around the longitudinal axis (5) of the shank (2) or around the longitudinal axis (5a ) of the tool tip (6) can be rotated, the tool (4) being rotated about the longitudinal axis (5) of the shank (2) via an actuating rod (7) which is rotatably mounted in the hollow shank (2) and is connected to the handle on the proximal side (3) is operatively connected and the actuating rod (7) is designed in two parts and consists of a distal section (8) mounted in the bendable tool tip (6) and a section (9) mounted in the proximal part of the shaft (2), and the two facing each other Faces of the sections (8 and 9) of the actuating rod (7) in the transition to the bendable tool tip (6) are in engagement with one another via face teeth (10). In order to create a medical instrument (1) of the type mentioned at the outset which, with a compact design, ensures a uniform jaw rotation regardless of the deflection of the tool tip (6), it is proposed according to the invention that the tooth flanks (12) of the individual teeth (11) of the two toothings (10) on the face side are designed to taper radially outwards and that the tooth flanks (12) of the individual teeth (11) of the two toothings on the face side (10) are also designed to taper radially inwards.