Knife Blade Carrier Spring Retention Mechanism

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Solution Overview

Problem

Existing knives with spring-loaded blade carriers often damage the spring when the blade needs to be changed, as the spring is overstretched during removal of the carrier.

Innovation Solution

A knife design where the blade carrier is guided within the housing, with a spring connected to a first clutch member and a second coupling element attached to the blade carrier or actuator, allowing the blade carrier to be removed without loosening the spring by detaching the coupling elements, and a holding part that prevents unintentional movement during blade replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the blade carrier is removed from the housing to change the blade, then the blade can be replaced, but the spring is overstretched and destroyed

Engineering Contradiction:
Improveblade replacement easeVSAvoidspring durability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The system is divided into separate functional components: the blade carrier assembly (with second coupling element) can be independently removed from the housing while the spring assembly (with first coupling element) remains intact in the housing. This segmentation allows blade replacement without affecting the spring.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling elements act as intermediaries between the spring and blade carrier. The first coupling element connects the spring to the housing, while the second coupling element connects the blade carrier to the actuation. These intermediary coupling mechanisms enable selective attachment and detachment of the blade carrier without transmitting excessive force to the spring.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the spring is kept connected to the blade carrier during removal, then the spring remains tensioned, but the spring becomes damaged due to overstretching

Engineering Contradiction:
Improvespring tension maintenanceVSAvoidspring structural integrity
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The spring connection is segmented from the blade carrier connection. The first coupling element maintains the spring's attachment to the housing, while the second coupling element manages the blade carrier attachment. This allows the spring to remain tensioned and connected to the housing while the blade carrier can be safely removed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The blade carrier assembly is extracted from the housing as a separate unit through the second coupling element, while the spring remains extracted and retained in the housing through the first coupling element. This selective extraction prevents the spring from being overstretched during blade carrier removal.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of operation

If a coupling mechanism is added to connect spring and blade carrier, then blade replacement is enabled, but the device complexity increases

Engineering Contradiction:
Improveblade changeabilityVSAvoidcoupling mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The coupling elements serve multiple functions: they connect the spring to the housing, connect the blade carrier to the actuation mechanism, and enable selective detachment for blade replacement. This multi-functionality reduces the need for additional specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The coupling elements are designed to automatically engage and disengage through the actuation mechanism, reducing the need for manual intervention or complex locking mechanisms. The system performs the coupling and uncoupling actions through its normal operation cycles.

Inventive Principle:
Principle #25Self-service

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

Enables easy blade replacement without damaging the spring, ensuring the spring remains tensioned and functional, while maintaining the knife's operational readiness.

Implementation Method 1

A spring is attached to the housing and to the blade carrier and biases the blade carrier into, for example, the safety position

Methodology Applied
Scientific EffectElastic restoring force: Elasticity

Implementation Method 2

A first coupling element is assigned to a carriage... A second coupling element is assigned to the blade carrier or the actuation... The second clutch member is releasably moveable into contact with the first clutch member

Methodology Applied
Scientific EffectMechanical force transmission: Mechanical Force

Data Source

PatentEP2703133B1Knife
Publication Date: 2016.08.31 MARTOR
  • EP2703133B1 patent drawingFigure 1
  • EP2703133B1 patent drawingFigure 2
  • EP2703133B1 patent drawingFigure 3~4

AI summary

The knife has a housing and an actuator (14), where a blade holder (13) carrying a blade (47) is shifted by the actuator between a safety position and a cutting position. The blade holder is biased by a spring (35) such as metal spring. The spring is attached to the housing and to an entrainment formation (25). Another entrainment formation (46) is provided on the blade holder or the actuator. The latter entrainment formation is releasably engageable with the former entrainment formation such that the former entrainment formation is moved by the latter entrainment formation.