Wrist-Mounted Knife with Sheath Locking Mechanism
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Solution Overview
Problem
Conventional knives are cumbersome to access in emergency situations, such as car accidents or self-defense, as they need to be retrieved from pockets or sheaths, which can be time-consuming and risky.
Innovation Solution
A bracelet design featuring a knife with a blade extending from a base that doubles as a handle, integrated with a flexible band and a sheath, providing a positive locking mechanism and a deflectable detent for secure enclosure and quick release, allowing the knife to be worn on the wrist for easy deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the knife is stored in a pocket, handbag, or belt sheath, then the knife is protected and carried, but it becomes cumbersome and time-consuming to access during emergencies
Solution Approach 1:
The knife system is segmented into modular components: a flexible band that can be worn on the wrist, a sheath that attaches to the band, and a knife that inserts into the sheath. This segmentation allows the knife to be carried close to the body in an easily accessible position rather than in a pocket or handbag, eliminating the time delay of reaching into a pocket during emergencies while maintaining protection through the sheath.
Solution Approach 2:
The knife is pre-positioned in a ready state by attaching the sheath to the flexible band worn on the wrist. This preliminary positioning ensures the knife is already in the optimal location for quick deployment during emergencies, eliminating the need to search for or reach into a pocket or handbag when time is critical.
2Ease of operation
If the knife is inserted into the sheath to attach to the wrist bracelet, then the knife can be worn on the wrist, but serious injury may occur as the sharp blade must be placed near the user's wrist
Solution Approach 1:
A handle guard serves as an intermediary component between the sharp blade and the user's wrist. The guard extends from the blade base and engages with a detent mechanism in the sheath, allowing the knife to be inserted into the sheath for wrist attachment without the blade contacting the user's skin. This intermediary structure enables safe handling and attachment while maintaining wrist wearability.
Solution Approach 2:
The handle guard is extracted as a separate protective component that isolates the dangerous blade edge from the user's wrist during insertion and attachment operations. By separating the protective function from the blade itself, the design allows the sharp edge to remain sharp while the guard provides a safe interface for handling and attachment near the wrist.
3Reliability
If the knife is secured in the sheath with a positive locking mechanism, then safety and prevention of loss are improved, but the release requires specific opposing forces that may be difficult to apply
Solution Approach 1:
The detent mechanism is designed as a spring-loaded dynamic component that automatically engages with the handle guard to secure the knife in the sheath. The spring allows the detent to flex during insertion and then locks into place, providing secure retention. For release, the spring-loaded nature allows the detent to be easily disengaged by applying opposing forces to the sheath and blade base, as the spring can compress to allow detent movement and then returns to its original position, making the release action simpler than static locking mechanisms.
4Adaptability or versatility
If the flexible band functions as part of the knife handle, then the bracelet can be worn on the wrist, but upward force on the cutting edge can cause the band to flex and the blade to rotate backward
Solution Approach 1:
The handle guard is designed with an asymmetric geometry that includes a gripping surface on one side and a locking engagement surface on the other. This asymmetric structure provides a stable purchase area for the user's thumb or forefinger, preventing the blade from rotating backward when cutting forces are applied. The gripping surface is positioned to counteract the flexing tendency of the flexible band, while the locking surface engages with the detent mechanism to provide additional rotational stability.
Data Source
AI summary
A bracelet or flexible band comprised of a flexible member that on one end is interconnected to a knife and on another end, is connected to a sheath that selectively receives the knife in the locking fashion. When needed, the knife is rotated within the sheath to facilitate release thereof from a lock that is integral with the sheath. Once removed from the sheath, the knife can be used for self-defense, cutting rope or cord in an emergency situation, or for general utility cutting tasks.