Folding Knife Torsion Spring Opening Assist Mechanism

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Folding knives with automatic or opening assist mechanisms often require a latch or trigger for opening, which can be inconvenient and may not provide sufficient safety, as the blade can unintentionally open when dropped or subjected to force.

Innovation Solution

A folding knife design incorporating a pair of torsion springs axially positioned on the blade axis pin within stationary bushings, where the springs are loaded in the closed position and transfer their force to the blade as it rotates, imparting rotational kinetic energy to drive the blade open and lock it in place, without the need for a latch or trigger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a latch or trigger mechanism is used for opening the blade, then the blade can be securely retained in the closed position, but the operation becomes more complex and may not provide sufficient safety against unintended opening

Engineering Contradiction:

ImprovesafetyVSAvoidmechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the latch or trigger mechanism from the knife structure, extracting the component that caused complexity while maintaining safety through an alternative spring-driven opening assist mechanism that provides reliable blade retention without the need for additional locking components

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The spring mechanism automatically provides opening assist force without requiring user activation of a latch or trigger, allowing the blade to be securely retained in closed position while enabling easy one-handed opening through natural user manipulation that triggers the spring-assisted motion

Inventive Principle:

Principle #25Self-service

2Ease of operation

If a spring mechanism is used to drive the blade open automatically, then opening convenience is improved, but the blade may unintentionally open when dropped or subjected to force

Engineering Contradiction:

Improveopening convenienceVSAvoidsafety

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The spring mechanism is designed to provide opening assist force only during the intended opening motion, with the spring gradually transferring force to the blade as it rotates from closed to open position, while the blade's weight and friction naturally prevent unintended activation during normal handling or dropping

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spring force parameters are calibrated to provide sufficient assist for intentional opening while remaining below the threshold force required to accidentally activate the blade during normal use or impact, creating a safe operating window that prevents unintended opening

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the same spring mechanism is used to both drive the blade open and retain it closed, then device complexity is reduced, but the spring must constantly switch between driving and retaining functions

Engineering Contradiction:

Improvemechanism simplicityVSAvoidspring action duration

Core Design Contradiction:

Device complexityVSDuration of action of moving object

Solution Approach 1:

The spring mechanism operates in periodic cycles, storing energy when the blade closes and releasing it during opening, with the spring force being gradually transferred to and from the blade in a controlled manner that allows the same mechanism to reliably perform both retaining and driving functions

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The spring acts as an intermediary energy storage device that mediates between the blade's closed and open positions, gradually transferring mechanical energy in both directions to enable the same component to perform opposing functions of retention and activation without requiring separate mechanisms

Inventive Principle:

Principle #24Intermediary (Mediator)

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 mechanism ensures the blade remains securely closed until intentionally opened and locks in the open position, enhancing safety and convenience by eliminating the need for a latch or trigger, while allowing for easy one-handed operation.

Implementation Method 1

When the blade is in the closed position the torsion springs are 'loaded' but do not apply their spring force to the blade

Methodology Applied

Scientific EffectElastic potential energy: Elasticity

Implementation Method 2

the paired springs, which act on the blade and thereby impart sufficient rotational kinetic energy to the blade that the inertia drives the blade into the fully open position

Methodology Applied

Scientific EffectRotational kinetic energy: Inertia

Data Source

PatentUS8572851B2Method of opening a knife blade

Publication Date: 2013.11.05 BENCHMADE KNIFE CO INC

AI summary

A folding knife incorporates an opening assist mechanism that functions to drive the blade from the closed to the open position. A torsion spring is retained axially on the blade axis pin and within a bushing that is stationary relative to the knife handle. One leg of the spring is fixed relative to the handle. The opposite leg of the spring extends through and rides in a partial annular groove in the bushing and acts on the blade as it is moved between the open and closed positions.