Spring-Locked Utility Knife Blade Carrier for Secure Positioning

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Solution Overview

Problem

Existing knives with spring-loaded blade carriers lack effective mechanisms for securely locking the blade in multiple positions, requiring manual holding during cutting operations and posing safety risks due to accidental blade exposure.

Innovation Solution

A knife design featuring a blade carrier with first and second locking elements, allowing secure locking in at least two positions, including a safety position, with a visible locking mechanism and adjustable blade extension, and a spring-biased system that prevents unintentional movement, enhancing safety and ease of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spring-loaded blade carrier is used without a locking mechanism, then the blade carrier can be easily moved between positions, but the blade cannot be securely locked and requires manual holding during cutting operations

Engineering Contradiction:
Improveease of blade carrier movementVSAvoidsecurity of blade positioning
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The blade carrier system is segmented into movable and lockable components. The blade carrier itself remains movable for easy positioning, while separate locking elements (first locking elements on blade carrier, second locking elements on housing) provide secure fixation when engaged. This segmentation allows the blade carrier to be easily moved when needed while providing reliable locking when required.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking mechanism is designed to be self-servicing during cutting operations. Once the blade carrier is positioned at a desired extension length, the locking elements automatically engage to secure the position without requiring continuous manual holding. The spring element maintains pressure on the locking elements to ensure automatic engagement and retention.

Inventive Principle:
Principle #25Self-service

2Reliability

If a locking mechanism is added to secure the blade carrier in multiple positions, then the blade can be locked without manual holding, but the device complexity increases

Engineering Contradiction:
Improvesecurity of blade positioningVSAvoidcomplexity of locking mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism merges multiple functions into integrated components. The first locking elements on the blade carrier and corresponding second locking elements on the housing work together as a unified system. The spring element combines positioning and locking functions, applying force to engage the locking elements while allowing easy release when needed. This merging reduces overall complexity compared to separate locking systems.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking mechanism is designed with multi-functionality to handle various blade carrier positions. The same locking elements can secure the blade carrier at multiple extension lengths, providing universal locking capability across different cutting positions. The spring-loaded design provides both positioning assistance and locking function simultaneously.

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

3Adaptability or versatility

If the blade carrier is made easily movable for adjustment, then the blade extension length can be changed freely, but the blade may accidentally expose and injure the user

Engineering Contradiction:
Improveadjustability of blade extensionVSAvoidrisk of accidental blade exposure
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The locking mechanism provides preliminary anti-action by automatically engaging locking elements when the blade carrier reaches a desired position. This prevents accidental movement or exposure of the blade during cutting operations. The spring element maintains continuous pressure on the locking elements, ensuring they remain engaged unless deliberately released, thereby counteracting any forces that might cause accidental blade exposure.

Inventive Principle:
Principle #9Preliminary anti-action

4Loss of information

If a visible locking mechanism is implemented, then the locking status can be monitored, but the device structure becomes more complex

Engineering Contradiction:
Improvevisibility of locking statusVSAvoidstructural complexity of locking mechanism
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The visible locking status is achieved by merging the functional locking components with visual indication features. The locking elements themselves are positioned and designed to be visible from the outside, allowing users to monitor locking status without adding separate indication mechanisms. This integration maintains structural simplicity while providing necessary visual feedback.

Inventive Principle:
Principle #5Merging (Combining)

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 ensures the blade carrier can be locked in multiple positions without manual holding, reducing the risk of accidental exposure and improving user safety through visual and tactile feedback, while allowing easy adjustment of blade extension.

Implementation Method 1

Spring elements are arranged between the housing and the blade carrier and bias the blade carrier into the safety position.

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4289574B1Knife
Publication Date: 2026.01.14 MARTOR
  • EP4289574B1 patent drawingFigure 1
  • EP4289574B1 patent drawingFigure 2
  • EP4289574B1 patent drawingFigure 3

AI summary

The invention relates to a knife with a housing (11) and a blade carrier (14) in which a blade (16) can be attached. The blade carrier (14) is movable within the housing (11) between a safety position, in which it is positioned in a rearward position such that the blade (16) does not project beyond any guards formed by the housing (11), and at least one cutting position, in which the blade (16) does project beyond the guards. The blade carrier (14) is moved by means of spring elements (26) arranged between the housing (11) and the blade carrier (14), which bias the blade carrier (14) into the safety position. The special feature is that the blade carrier (14) comprises first locking elements (17) which can be releasably engaged with second locking elements (18) on the housing (11) to lock the blade carrier (14) in at least one safety position and/or in at least one cutting position.