Offset Gear Rotation Mechanism for Precise Surgical Jaw Positioning
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Solution Overview
Problem
Conventional electrosurgical vessel sealers face difficulties in properly positioning the jaws due to the direct coupling of the rotation knob with the shaft, making it hard to grasp and rotate the knob for precise orientation.
Innovation Solution
A rotation mechanism with a knob offset from the shaft and interconnected via gears, allowing the shaft to rotate faster than the knob, with a gear ratio greater than 1:1, enabling easier and more precise jaw orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotation knob is directly coupled to the shaft, then the structure is simple, but the knob is hard to grasp and rotate for precise jaw positioning
Solution Approach 1:
A gear mechanism is introduced as an intermediary between the rotation knob and the shaft. The knob is offset from the shaft and connected via gears, allowing the user to rotate the knob easily while the gear ratio translates this rotation into faster shaft rotation for precise jaw positioning. This mediator resolves the contradiction by making the knob easier to grasp and rotate without directly coupling it to the shaft.
2Measurement precision
If the knob rotates at the same rate as the shaft, then the mechanism is simple, but it is difficult to position the jaws properly
Solution Approach 1:
The gear ratio between the knob and the shaft is changed to create a differential rotation rate. Specifically, the shaft rotates faster than the knob due to the gear ratio greater than 1:1. This parameter change allows the user to rotate the knob through a larger angle for the same shaft rotation, providing finer control and more precise jaw positioning while maintaining a mechanically simple gear coupling.
3Ease of operation
If the knob is positioned concentrically with the shaft, then the structure is compact, but the knob is hard to access and operate
Solution Approach 1:
The knob is positioned asymmetrically, offset from the shaft axis rather than being concentric with it. This asymmetric arrangement improves accessibility and ease of operation, allowing the user to easily grasp and rotate the knob. The offset position, combined with the gear mechanism, maintains a compact overall structure while significantly improving ergonomics and user interaction.
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 offset knob design facilitates easier and more precise positioning of the jaws, enhancing user accessibility and operational efficiency during surgical procedures.
Implementation Method 1
a knob (34) offset from the shaft (28) and interconnected via a set of gears (54, 56) so that the shaft (28) rotates faster than the knob (34)
Data Source
AI summary
An electrosurgical instrument having a knob with an internal gear, a shaft extending from the body with an external gear that is coupled to the internal gear, and a pair of jaws mounted to the shaft. The internal gear and the external gear have a gear ratio greater than 1:1 so that the shaft and jaws rotate at a faster than the knob when it is turned by a user. The axis of rotation of the knob is offset from the axis of rotation of the shaft so that the knob can project asymmetrically from the body for easier rotation by a user.