Cantilever Spring Force Limiting Assembly for Surgical Instruments
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Solution Overview
Problem
Existing surgical instruments with force limiting mechanisms are complex and costly, occupying significant space, necessitating a compact and simple solution to limit user-applied force to the jaws.
Innovation Solution
A force limiting assembly featuring a cantilever spring and drive shaft mechanism, where the cantilever spring is preloaded and further biased as the lever pivots, absorbing excess force and reducing the force transmitted to the jaws, with adjustable parameters for customization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional force limiting mechanisms are used, then force can be limited, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the force limiting function with the existing lever and drive shaft mechanism by integrating a cantilever spring directly into the lever assembly. The spring is positioned within the lever structure and works in conjunction with the drive shaft, merging multiple functions (force limiting, motion transmission, and positioning) into a unified mechanism rather than adding a separate complex force limiting device.
Solution Approach 2:
The cantilever spring automatically limits force through its inherent elastic properties. As the lever pivots and the spring becomes more fully biased, it naturally reduces the force transmitted to the drive shaft without requiring external control systems, sensors, or additional actuation mechanisms. The spring's elastic deformation self-regulates the force transmission.
2Reliability
If conventional force limiting mechanisms are used, then force can be limited, but manufacturing cost increases
Solution Approach 1:
The force limiting function is merged with the existing lever and drive shaft components. The cantilever spring is integrated into the lever structure, and the force limiting action occurs through the natural interaction between the spring, lever, and drive shaft. This eliminates the need for separate force limiting components that would increase manufacturing complexity and cost.
Solution Approach 2:
The cantilever spring is a simple, inexpensive elastic component that can be easily manufactured using standard spring-making processes. Compared to complex mechanical force limiting mechanisms involving multiple moving parts, sensors, and control systems, the spring represents a cost-effective solution that achieves the same force limiting function with minimal material and manufacturing investment.
3Reliability
If conventional force limiting mechanisms are used, then force can be limited, but space in the surgical device increases
Solution Approach 1:
The cantilever spring is nested within the lever structure, with the spring positioned inside the lever assembly. The spring's plates extend on either side of the drive shaft, and the overall spring structure is contained within the existing lever and handle housing, utilizing available space efficiently rather than requiring additional external space.
Solution Approach 2:
The force limiting mechanism is merged with the existing lever and drive shaft assembly. The cantilever spring, lever, and drive shaft work together as an integrated unit, eliminating the need for separate force limiting components that would occupy additional space. The mechanism achieves force limiting within the existing spatial envelope of the surgical instrument.
4Volume of moving object
If a compact force limiting mechanism is designed, then space is reduced, but manufacturing complexity may increase
Solution Approach 1:
The compact design is achieved by nesting the cantilever spring within the lever structure. The spring's plates extend on either side of the drive shaft, and the entire spring assembly is contained within the existing lever and handle housing. This nested arrangement achieves space efficiency without requiring complex multi-component mechanisms.
Solution Approach 2:
The cantilever spring's inherent elastic properties provide the force limiting function automatically. The spring becomes more fully biased as the lever pivots, naturally reducing transmitted force without requiring complex control systems, sensors, or additional actuation mechanisms. This self-regulating behavior achieves compact design without increasing mechanism complexity.
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 effectively limits user-applied force to the jaws, preventing damage while providing user feedback, and is more cost-effective and space-efficient than existing mechanisms, adaptable for various surgical instruments.
Implementation Method 1
the cantilever spring to become more fully biased, thereby reducing the amount of force that a user may apply to the drive shaft of the surgical instrument via operation of the lever
Data Source
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AI summary
A force limiting assembly for a surgical instrument that has a handle and a lever pivotally mounted to the handle at a pivot point for movement of an internal drive shaft. The lever is coupled to the drive shaft by a cantilever spring that is positioned within the lever. The free end of the cantilever is spaced apart from the pivot point of the lever and coupled to the drive shaft via stops positioned on the drive shaft on either side of the free end of the cantilever spring. As the lever is pivoting by a user, the forces move the drive shaft and bias the cantilever spring, thereby reducing and ultimately limiting the amount of force that a user may apply to the drive shaft via operation of the lever.