Replaceable Blade Knife with Secure Retention and Safe Ejection
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Solution Overview
Problem
Existing replaceable blade knives suffer from issues of blade unrestraint, leading to potential injury and difficulty in safe ejection, especially in slippery conditions, posing risks to users in outdoor and medical applications.
Innovation Solution
A replaceable blade knife design featuring an elongated body with a movable ejector element and deflector mechanism that securely restrains the blade during use and allows safe ejection by deflecting the blade laterally, preventing direct finger contact during the ejection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blade is made easily removable for replacement, then blade replacement convenience is improved, but blade restraint reliability deteriorates causing potential injury
Solution Approach 1:
The knife employs a dynamic retention system where a spring-loaded arm provides continuous rearward pressure on the blade to maintain engagement during use. The blade can be easily removed by pressing a release button that disengages the retention arm, allowing quick replacement while ensuring secure holding during operation.
Solution Approach 2:
The patent introduces an intermediary ejection mechanism that mediates between the user and the blade during removal. A spring-loaded ejection arm with a buffered surface provides controlled forward motion to push the blade out safely, preventing direct finger contact with the sharp edge while maintaining simple blade replacement.
2Device complexity
If the blade ejection mechanism allows direct finger contact for simplicity, then device complexity is reduced, but safety deteriorates due to potential finger injury
Solution Approach 1:
The ejection mechanism uses a spring-loaded arm with a buffered surface as an intermediary between the user's finger and the blade. When the release button is pressed, this intermediary component pushes the blade forward and off the boss, eliminating the need for direct finger contact with the sharp edge while keeping the mechanism simple.
Solution Approach 2:
The ejection system is self-actuating through a spring-loaded arm that automatically propels the blade forward when the retention lock is disengaged. The buffered surface on the ejection arm provides a safe contact point for the user's finger, allowing the mechanism to serve its own safety function without adding complex controls.
3Reliability
If the blade retention force is increased to prevent accidental disengagement, then blade restraint reliability is improved, but ease of operation deteriorates making blade removal difficult
Solution Approach 1:
The retention system uses a spring-loaded arm that dynamically adjusts the retention force. During normal use, the spring maintains strong rearward pressure on the blade to prevent accidental disengagement. For blade removal, pressing the release button temporarily disengages the retention arm, allowing easy blade extraction without requiring excessive force.
Solution Approach 2:
The ejection mechanism performs preliminary action by pre-loading a spring that is ready to propel the blade forward. When the release button is pressed, this pre-stored energy is immediately released, pushing the blade off the boss without requiring the user to manually pry or lever the blade loose, making removal easy despite strong retention during use.
Data Source
AI summary
Replaceable blade knives have an elongated boss sized to closely receive an elongated aperture of the planar blade, a deflector element connected to the elongated body and operable to engage a rear end of the planar blade to deflect a selected portion of the blade defining a rear portion of the elongated aperture laterally between a retention position in which the selected portion engages the boss and a clear position in which the selected portion is clear of the rear portion of the boss, and a movable ejector element having a ejector surface adjacent to the rear edge of the blade and operable to eject the blade from the blade attachment facility in response to forward motion of the ejector element when the selected portion of the blade is in the clear position.