Four Bar Knife Linkage for Safe One-Handed Operation
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Solution Overview
Problem
Folding knives often risk catching a user's finger between the blade and handle during closure due to the scissoring motion, and the load-bearing requirements on the single main pivot can be excessive, leading to potential breakage.
Innovation Solution
A four-bar and four-pivot mechanical linkage system that rearranges knife components in a non-scissoring motion, distributing load across two longitudinally oriented pivot points and preventing hand contact with the blade during closure, utilizing a parallelogram-like mechanism for both parallel and anti-parallel formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single main pivot is used in folding knives, then the structure is simple, but the load-bearing requirements become excessive and the knife may break
Solution Approach 1:
The single main pivot is segmented into two separate pivot points (first pivot point and second pivot point) positioned at different locations on the blade tang. This segmentation distributes the load-bearing requirements across multiple pivots rather than concentrating all stress on one pivot, thereby reducing the structural demands on each individual pivot while maintaining overall knife strength.
2Productivity
If the blade folds with a scissoring motion, then the folding action is efficient, but the user's finger may be caught between the blade and handle
Solution Approach 1:
A finger guard is introduced as an intermediary component between the blade and handle. The finger guard extends from the handle and positions itself to block the user's finger from entering the danger zone where the blade contacts the handle during closing. This intermediary element prevents direct contact between the finger and the moving blade while allowing the scissoring folding motion to continue efficiently.
3Strength
If two pivot points are used, then load is distributed and structural demands are reduced, but the mechanism complexity increases
Solution Approach 1:
The two pivots are merged into a single integrated blade tang structure. Both the first pivot point and second pivot point are positioned on the same blade tang, allowing them to function as a coordinated pair while being structurally unified. This merging approach distributes load across two points without requiring separate blade sections or complex additional components, thus reducing mechanism complexity while maintaining the load-distribution benefits.
Data Source
AI summary
A folding knife that uses a four bar linkage mechanism to open and close. The knife can include a means of one hand opening and closing as well as a means to become latched in, and released from, a fixed position. The four bar linkage knife includes a blade, a handle, and the motion of a four bar linkage to open and close the knife. The four bar knife provides inherent safety because the four bar linkage motion can not fold onto the users hand.