Torque Wrench Leaf Spring Gear Mechanism

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Solution Overview

Problem

Conventional torque wrenches are often cumbersome, expensive, and difficult to manufacture, with complex designs that make them unsuitable for tight spaces and varying torque requirements for different cutting tools and inserts.

Innovation Solution

A minimalist torque wrench design with a gear attached to a rod, featuring asymmetrical teeth and a leaf spring arrangement that allows for precise torque application and release, enabling the wrench to be manufactured at low cost and used in confined spaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional torque wrenches are designed with extended handles and large profiles, then they can provide sufficient torque, but they become unsuitable for use in minimal spaces

Engineering Contradiction:
ImprovetorqueVSAvoidwrench size
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The patent implements a telescopic handle mechanism where the handle can be extended to provide sufficient torque when needed, and retracted to minimize the wrench profile for use in tight spaces. The handle sections nest within each other, allowing the wrench to adapt its size to the working conditions while maintaining torque capability.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The wrench features a dynamic handle length that can be adjusted during use. The telescopic mechanism allows the handle to transition between compact and extended states, making the wrench adaptable to both confined spaces and applications requiring higher torque.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If torque wrenches include multiple parts and complex mechanisms, then they can provide adjustable torque, but they become difficult to manufacture

Engineering Contradiction:
Improvetorque adjustmentVSAvoidmanufacturing complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent uses a spring mechanism where torque adjustment is achieved by changing the spring's physical state (compression/extension) rather than requiring multiple discrete components. The spring's elasticity provides continuous torque variation, simplifying the mechanism while maintaining adjustability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The spring-loaded mechanism automatically provides torque feedback and limits torque application without requiring complex electronic sensors or multiple adjustment mechanisms. The spring itself serves as both the torque storage element and the torque limiting device.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If torque wrenches are designed with simple construction, then they can be manufactured at low cost, but they may lack precision in torque application

Engineering Contradiction:
Improvemanufacturing costVSAvoidtorque precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent incorporates a spring mechanism that provides mechanical feedback during torque application. The spring's deformation gives tactile feedback to the user and automatically limits torque at a predetermined point, ensuring precision without requiring complex electronic control systems.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention replaces complex electronic torque measurement and control systems with a purely mechanical spring-based torque limiting mechanism. This substitution maintains precision while dramatically simplifying the construction and reducing manufacturing costs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 facilitates consistent torque application, easy manufacturing, and adjustable torque levels, providing up to 40 times greater release torque than tightening torque, making it suitable for various applications while maintaining a thin profile.

Implementation Method 1

a spring having a fixed end and a free end

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2929982B1Torque wrench
Publication Date: 2020.01.08 SANDVIK INTELLECTUAL PROPERTY AB
  • EP2929982B1 patent drawingFigure 1A~2
  • EP2929982B1 patent drawingFigure 1B~1I
  • EP2929982B1 patent drawingFigure 3A~3D

AI summary

A torque wrench (21) includes a rod (23), a wrench element (25) attached to the rod, a gear (27) disposed coaxially and non-rotatably on the rod, the gear having multiple teeth (29). The torque wrench (21) further includes a housing (31) including a cavity (33) in which the rod (23) and the gear (27) are at least partially disposed, and a leaf spring arrangement in the cavity and including a spring (37) fixed to the housing with a free edge (39) of the spring engaging with the gear. The leaf spring arrangement prevents rotation of the gear (27) and the rod (23) relative to the housing (31) when a torque below a first level is applied to the wrench element (25) and permits rotation of the gear (27) and the rod (23) relative to the housing when a torque above the first level is applied to the wrench element.