Surgical Retaining Arm Automatic Retightening Mechanism
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Solution Overview
Problem
Existing surgical retaining arms require manual retightening due to elastic and plastic changes, leading to a decrease in locking force over time, and lack a mechanism for automatic retightening without user intervention.
Innovation Solution
A surgical device with a flexible articulated arm that incorporates a self-actuating tightening mechanism with a retightening reserve, utilizing spring force or an energy source to maintain the locked state, allowing automatic retightening and compensation for length changes, ensuring consistent locking force over a long period without user intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a manual tightening device such as a screw mechanism is used to tighten the traction cable, then the tensile force can be adjusted and fixed at a certain point, but the tightening force decreases over time due to elastic and plastic changes in the articulated arm segments and elongation of the cable, requiring manual retightening
Solution Approach 1:
The tightening mechanism is designed to automatically retighten itself by utilizing the spring force already present in the system. When the articulated arm segments compress or the cable elongates, the spring automatically generates additional tensile force to maintain the locking state without requiring manual intervention. This self-service mechanism converts the harmful elastic and plastic deformations into a useful retightening action.
Solution Approach 2:
The tightening mechanism transitions from a static manual screw adjustment to a dynamic self-adjusting system. The spring force continuously adapts to compensate for changes in length of the articulated arm segments and cable, maintaining optimal tightening force throughout the operational duration. This dynamic adjustment ensures the locking force remains effective over extended periods.
2Reliability
If the articulated arm segments are compressed and the cable is elongated under load to lock the arm, then the arm can be securely locked, but the entire articulated arm becomes shorter and the cable becomes longer, causing the retaining arm to yield and become loose
Solution Approach 1:
The system pre-compensates for length changes by incorporating a spring into the tightening mechanism before operation begins. The spring is pre-loaded to provide continuous tensile force that counteracts the compression of articulated arm segments and elongation of the cable. This preliminary action ensures that the tightening force is maintained despite the changing lengths of the arm and cable during operation.
Solution Approach 2:
The spring force mechanism changes the physical parameters of the system by converting the harmful length changes (compression of segments, elongation of cable) into a useful increase in tensile force. As the segments compress and cable elongates, the spring's elastic potential energy converts to kinetic energy, automatically increasing the tightening force to compensate for the length changes and maintain reliable locking.
3Device complexity
If a mechanical stop is used to limit the travel of the adjustment mechanism, then the mechanism has a defined range of motion, but the compression of articulated arm segments and elongation of the cable cannot be compensated
Solution Approach 1:
The invention removes the mechanical stop from the adjustment mechanism, extracting the constraint that prevented compensation for length changes. By eliminating this stop, the spring force mechanism is freed to continuously adjust and compensate for the compression of articulated arm segments and elongation of the cable, maintaining reliable locking without the limitation of a fixed travel range.
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 device maintains a consistent locking force over time by automatically retightening the articulated arm, ensuring reliable operation in surgical procedures without the need for manual intervention, even with changes in length due to compression or expansion.
Implementation Method 1
the adjustment mechanism being moved by spring force
Implementation Method 2
the individual links of the movable arm are subject to a certain deformation and compression during the tensile force application
Implementation Method 3
a cable passed through the center of these links, the distal end of which is attached to the last movable link of the arm and the proximal end of which can be moved in the longitudinal direction by a tightening mechanism
Implementation Method 4
the links of the arm are pressed against each other when the cable is pulled back in the longitudinal direction, the arm being locked thereby
Data Source
AI summary
A surgical device for stabilizing tissue or positioning organs, or for positioning and holding surgical instruments and devices during a surgical intervention, includes a main body and a flexible arm. The flexible arm can be fastened to the main body, which can be brought into different positions and/or locations and which can be locked in a desired positioning by a tightening mechanism. The tightening mechanism can be tightened and/or released self-actingly and/or by an energy source. In a locked state of the flexible arm, the tightening mechanism has a retightening reserve, and the flexible arm can be automatically retightened in order to maintain its locked state, in particular by an introduction of energy from the energy source or self-actingly, by utilization of the retightening reserve. A retightening mechanism for use in the surgical device automatically retightens a flexible arm when in a locked state to maintain its locked state.