Articulated Locking Members for Screwdriver Direction Switching

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Solution Overview

Problem

Existing screwing tools with direction-switchable freewheel locks lack efficient mechanisms for independent movement of locking members, leading to suboptimal engagement and disengagement of locking teeth, affecting rotational direction control.

Innovation Solution

The locking members are designed to move articulately relative to each other, with hook projections and L-shaped switching extensions, allowing for independent engagement with the peripheral toothing in different switching positions, and a spring-loaded mechanism for tensioning the switching elements, enabling seamless direction switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If locking members are connected using the same material as a single piece, then manufacturing is simplified, but the ability to independently engage and disengage locking teeth is reduced

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidengagement and disengagement efficiency
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The locking mechanism is divided into separate locking members (first locking member and second locking member) that can move independently relative to each other. Each locking member has its own locking teeth that can independently engage with the circumferential toothing, allowing for more efficient engagement and disengagement operations while maintaining manufacturing feasibility through modular construction

Inventive Principle:
Principle #1Segmentation

2Device complexity

If locking members move rigidly together, then structural simplicity is maintained, but precise control over rotational direction is compromised

Engineering Contradiction:
Improvestructural simplicityVSAvoidrotational direction control precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The locking members are designed with relative movement capability through hinge connections and switching extensions. This dynamic configuration allows the locking members to independently position themselves for precise engagement with the circumferential toothing in different switching positions, enabling accurate control over the rotational direction of the output member while maintaining reasonable structural complexity

Inventive Principle:
Principle #15Dynamics

3Device complexity

If switching mechanism lacks spring-loaded tensioning, then device complexity is reduced, but seamless direction switching is compromised

Engineering Contradiction:
Improveswitching mechanism complexityVSAvoiddirection switching smoothness
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

A switching spring is pre-loaded to automatically tension the switching extensions when the switching element rotates. This preliminary action ensures that the locking members are properly positioned and engaged before the switching operation is complete, enabling seamless direction switching without requiring complex external actuation mechanisms

Inventive Principle:
Principle #10Preliminary action

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

This design ensures precise control over rotational direction, allowing the output member to be freely rotatable in one direction while locked in the other, with enhanced engagement and disengagement of locking teeth, improving the tool's operational efficiency.

Implementation Method 1

A spring-loaded control flank can be arranged within the switching element. The switching spring can in turn be supported on a locking plunger

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The locking members can preferably move relative to one another in a hinge-like manner. For this purpose, hook projections which engage with one another are provided

Methodology Applied
Scientific EffectHinge mechanism: Hinge

Implementation Method 3

locking members located in a pocket of the drive member, each having a locking toothing for rotationally locking engagement in the circumferential toothing

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentEP3408055B1Screwdriver having a changeable direction freewheel lock
Publication Date: 2024.04.10 WERA WERKZEUGE GMBH
  • EP3408055B1 patent drawingFigure 1~2
  • EP3408055B1 patent drawingFigure 3
  • EP3408055B1 patent drawingFigure 4

AI summary

The invention relates to a screwdriver having a changeable direction freewheel lock, having a drive output member (2) that is mounted so as to be rotatable about an axis (a) in a bearing eye (6) of a drive input member (1) and has a circumferential toothing (5) and a drive-output profile portion (4), and locking members (10, 20) that are inserted in a pocket (17, 27) of the drive input member (1) and each have a locking toothing (11, 21) for engaging with the circumferential toothing (5) in a manner preventing rotation. What is essential is that the locking members (10, 20) are two bodies that are movable relative to one another, can be displaced in an articulated manner with respect to one another and each have a switching extension (13, 23) which project into the same switching recess (30) of a switching member (3).