Screwing Tool Dual Torque Limiting Arrangements

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Solution Overview

Problem

Existing screwing tools with torque limiting arrangements often require increased stroke of compression springs to overcome limit torque, and existing designs are not optimized for compact, efficient torque transmission.

Innovation Solution

A screwing tool design where a single spring element supports two torque-limiting arrangements with inclined flanks of different pitch angles, allowing for two distinct breakaway torques, and featuring axially movable torque limiting elements connected to a housing in a rotationally fixed manner, enabling efficient torque transmission with a compact flat housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single spring element acts on two torque-limiting arrangements, then the device complexity is reduced and compactness is improved, but the manufacturing precision and alignment accuracy become more difficult to achieve

Engineering Contradiction:
Improvenumber of spring elementsVSAvoidalignment accuracy of torque-limiting arrangements
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent combines two separate spring elements into a single spring element that simultaneously acts on both torque-limiting arrangements. This merging reduces the number of components and simplifies the overall structure, achieving compactness while maintaining the functionality of providing controlled torque to both arrangements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single spring element is designed to perform multiple functions by simultaneously providing spring force to both torque-limiting arrangements. This multi-functionality allows one component to replace what would traditionally require two separate spring elements, reducing device complexity while maintaining precise torque control capabilities.

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

2Adaptability or versatility

If two torque-limiting arrangements with different pitch angles are used, then the versatility and adaptability are improved, but the device complexity increases

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the torque transmission function into two separate torque-limiting arrangements, each with different pitch angles tailored to specific torque requirements. This segmentation allows each arrangement to be optimized for its specific function while both are integrated into a single compact device, achieving versatility without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different pitch angles are assigned to different torque-limiting arrangements based on their specific functional requirements. This local differentiation allows each arrangement to have optimized geometric properties for its intended torque range, while the overall device structure remains unified and compact through shared components like the single spring element and housing.

Inventive Principle:
Principle #3Local quality

3Force

If the stroke of compression spring is increased to overcome limit torque, then the torque transmission capability is improved, but the length of the tool increases

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidstroke length
Core Design Contradiction:
ForceVSLength of moving object

Solution Approach 1:

The patent resolves the contradiction between torque transmission capability and stroke length by changing the dimensional approach to torque limitation. Instead of relying solely on a long axial stroke, the design uses inclined flanks with optimized pitch angles that convert axial spring force into rotational torque more efficiently, reducing the required stroke length while maintaining high torque transmission capability.

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

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 allows for efficient transmission of two different torques with a compact tool, enabling high torque application while maintaining a small form factor, suitable for miniature tools.

Implementation Method 1

a spring element (9) which acts on a first torque limiting arrangement (5, 7) and a second torque limiting arrangement (6, 8)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The force of the spring and the pitch angle of the inclined flanks define the breakaway torque of the torque-limiting arrangement

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentEP3793775B1Screwing tool for transmitting two set torques
Publication Date: 2024.06.12 WERA WERKZEUGE GMBH
  • EP3793775B1 patent drawingFigure 1~2
  • EP3793775B1 patent drawingFigure 3
  • EP3793775B1 patent drawingFigure 4~5

AI summary

The invention relates to a screwing tool for transmitting a set torque. Two torque-limiting arrangements (5, 7) are provided that are biased by the same spring element (9).