Trigger Knife Linkage Assembly for Blade Retraction
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Solution Overview
Problem
Existing trigger knives are overly sensitive, causing the blade to rebound prematurely during cutting, and have insecure safety lock structures that increase the risk of accidental blade ejection and user injury.
Innovation Solution
A trigger knife design featuring a linkage assembly with a gear-rack mechanism, an elastic part for controlled blade retraction, and a secure locking block to ensure the blade automatically retracts after cutting and prevents sudden ejection, with a rotatable trigger and connecting plate for extended blade ejection length and secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the trigger knife uses a simple rebound structure, then the blade can retract automatically, but the blade rebounds prematurely before cutting due to over-sensitivity
Solution Approach 1:
The patent introduces a linkage assembly with gear-rack mechanism as an intermediary between the trigger and blade holder. The first rack engages with first drive gear, which engages with second drive gear, which engages with second rack connected to the connecting plate. This multi-stage mechanical transmission system mediates the trigger's movement, providing controlled, progressive blade ejection that prevents premature rebound while maintaining automatic retraction functionality.
2Device complexity
If the trigger knife uses a non-fully automatic rebound structure, then the structure is simpler, but the blade does not rebound automatically after leaving the cutting surface
Solution Approach 1:
The elastic part is configured to provide elastic force for the blade to retract into the cavity of the knife housing. The connecting plate is movably connected to the knife holder, allowing the blade holder to automatically rebound to the initial position after cutting without requiring manual intervention. The system serves itself by using the elastic potential energy stored during blade ejection to automatically drive the blade back into the housing.
3Device complexity
If the trigger knife uses an insecure safety lock structure, then the structure is simpler, but the trigger is easy to eject accidentally causing sudden blade ejection and increased injury risk
Solution Approach 1:
The locking block is movably installed onto the knife housing with a movement track that can be staggered or intersected with the trigger's movement track. The locking block restricts the movement of the knife holder to lock the blade in the cavity of the knife housing. This preliminary locking mechanism prevents accidental trigger ejection by requiring deliberate, coordinated movement to disengage the lock, thereby counteracting unintended activation before it can occur.
4Device complexity
If the trigger knife uses a direct connection between trigger and blade holder, then the structure is simpler, but the blade ejection length is insufficient for cutting thicker materials
Solution Approach 1:
The linkage assembly transforms the trigger's rotational movement into linear movement through the gear-rack mechanism. The first rack converts rotation to linear motion of the first drive gear, which through meshing with the second drive gear, converts it again to drive the second rack. This multi-dimensional transformation of movement types extends the blade ejection stroke, enabling sufficient cutting depth for thicker materials while maintaining a compact overall structure.
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 design reduces user injury risk by preventing premature blade rebound and ensuring secure locking, allowing for effective cutting of thicker materials with improved safety performance.
Implementation Method 1
the elastic part is configured to provide an elastic force for the blade to retract into the cavity of the knife housing
Data Source
AI summary
A trigger knife, including a knife housing, a knife holder, a blade, an elastic part, a trigger, a linkage assembly, a connecting plate. When the trigger is rotated outwards, the elastic part is deformed, and the linkage assembly drives the connecting plate to move and enables the knife holder to move to a first blade ejection position. When one end of the blade is lifted, the knife holder is enabled to fit with an inner wall of the knife housing, the knife holder to move to a second blade ejection position, and the connecting plate is fastened onto the knife housing and separated from the knife holder. When the end of the blade is moved down, the knife holder is enabled to move down, the elastic part is restored from the deformation to enable the knife holder to move to a rebound position.