Directionally Reversible Locking Device for Screwdriver

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Solution Overview

Problem

Existing screwing tools require complex mechanisms with multiple springs and protrusions to achieve directional locking, which complicates production and usage, and often result in inefficient force distribution and engagement between the switching extension and actuating recess.

Innovation Solution

A single spring element, preferably a leaf spring, is used to act on the switching projection in different directions, overcoming an over-center position and providing a favorable lever technology arrangement, allowing the switching projection to engage in a tooth gap and hold the locking body in place, with the spring element positioned to change its effective direction relative to the switching extension during rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple springs and protrusions are used to achieve directional locking, then the locking mechanism can be switched between two positions, but the device complexity increases and production becomes more complicated

Engineering Contradiction:
Improvedirectional locking functionVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple springs and protrusions into a single integrated spring element that performs multiple functions: it provides the locking force, enables directional switching, and engages with the actuating recess. This merging reduces the number of components from multiple separate springs and protrusions to one unified element, simplifying the mechanism while maintaining the directional locking function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spring element is designed as a multi-functional component that simultaneously serves as a locking element, a switching actuator, and a force transmission element. It engages with the actuating recess to switch the locking body between two positions while maintaining constant engagement force, thereby replacing multiple specialized components with a single universal element.

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

2Device complexity

If a single spring element is used to act on the switching projection, then the device complexity is reduced, but the force distribution and engagement efficiency may be insufficient

Engineering Contradiction:
Improvemechanism simplicityVSAvoidforce distribution
Core Design Contradiction:
Device complexityVSForce

Solution Approach 1:

The spring element is designed with specific geometric features including an actuating recess with particular shape and orientation, and a switching projection with optimized geometry. The spring's force is concentrated at specific contact points where it engages with the actuating recess, creating localized high-force zones that ensure efficient force transmission despite the overall simplicity of the mechanism.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The spring element utilizes three-dimensional spatial arrangement to achieve effective force distribution. The actuating recess is positioned and oriented in space to receive the switching projection at an optimal angle, allowing the spring to exert force in multiple directions simultaneously through its elastic deformation, thereby compensating for the reduction in component count.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If the switching extension protrudes into a free space with a compression spring, then the locking body can be switched between positions, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveswitching operationVSAvoidassembly precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The spring element is designed to be self-centering and self-aligning through its geometric features. The actuating recess and switching projection are shaped to guide each other during assembly, allowing the components to find their correct relative positions automatically. This self-alignment mechanism reduces the need for high-precision manual assembly while maintaining smooth switching operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The spring element provides built-in compliance and tolerance compensation through its elastic properties. During assembly, the spring can deform to accommodate minor dimensional variations in the mating parts, effectively cushioning against manufacturing tolerances. This pre-built compliance allows for easier assembly without requiring extremely tight tolerances while ensuring reliable operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 configuration simplifies the mechanism, reduces the need for additional components, and ensures robust, efficient engagement and release of the locking mechanism, allowing for easy assembly and effective directional control of the output member's rotation.

Implementation Method 1

a spring element (10) acts on the switching extension (7) in such a way that the teeth (6) of the blocking body (3) engage in the external teeth (5)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3057741B1Screwing tool with directionally reversible locking device
Publication Date: 2020.04.22 WERA WERKZEUGE GMBH
  • EP3057741B1 patent drawingFigure 1~2
  • EP3057741B1 patent drawingFigure 3~4
  • EP3057741B1 patent drawingFigure 5

AI summary

The invention relates to a screwing tool having a drive member (1), a driven member (2) which is mounted on the drive member (1) such that it can be rotated about a rotational axis (D), and having a reversible locking device which has a locking body (3) which engages into a toothing system (5) of the driven member (2) and can be displaced between two switching positions by means of a switching projection (7) of a switching member (4) which can be pivoted about a switching axis (S), in which switching positions the rotatability of the driven member (2) is locked either in one or in the other rotational direction. In order to improve a screwing tool of this type in an advantageous manner in terms of production technology and use, it is proposed that the switching projection (7) which protrudes from the locking body (3) engages into an actuating cut-out (8) of the switching member (4) in a pivotably movable manner in relation to the switching member (4).