Roller-Driven Wrench Mechanism for Confined-Space Torque

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Solution Overview

Problem

Ratchet wrenches require significant angular movement of the handle to rotate fasteners, limiting their use in confined spaces and featuring mechanisms with backlash or lost motion during reverse rotation.

Innovation Solution

A combination box and roller wrench design with a cylindrical inside wall and annular cage mechanism that uses wedging elements to transmit torque in one direction and prevent rotation in the reverse direction, minimizing the required angular movement and allowing operation in restricted spaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If ratchet wrenches use traditional spring-loaded pawl mechanisms, then they can prevent reverse rotation, but they require large angular movement of the handle which eliminates use in confined environments

Engineering Contradiction:
Improveusability in confined environmentsVSAvoidrequired angular movement of handle
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent changes the fundamental operating parameters of the ratchet mechanism by replacing the traditional pawl-and-ratchet system with a roller-based mechanism that uses inclined ramps. This allows the wrench to achieve unidirectional torque transmission with minimal angular movement, enabling use in confined spaces where traditional ratchets cannot operate.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention substitutes the conventional mechanical pawl-and-ratchet system with a roller-based mechanism using inclined planes and elastic members. This mechanical substitution eliminates the need for large angular movements while maintaining the one-way torque transmission function, thereby enabling operation in confined environments.

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

2Reliability

If ratchet wrenches use cylindrical rollers with springs to minimize backlash, then lost motion during reverse movement is reduced, but the mechanism becomes more complex

Engineering Contradiction:
Improveminimization of backlash and lost motionVSAvoidcomplexity of motion transmission mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the driven body into multiple segments, each with its own roller and elastic member assembly. This segmentation allows each component to independently minimize backlash through precise engagement with the inclined ramps, while the modular structure manages complexity by repeating standardized units rather than creating a single complex mechanism.

Inventive Principle:
Principle #1Segmentation

3Power

If traditional ratchet mechanisms are used, then torque transmission in one direction is achieved, but significant lost motion occurs during reverse movement

Engineering Contradiction:
Improvetorque transmission efficiencyVSAvoidlost motion during reverse rotation
Core Design Contradiction:
PowerVSLoss of time

Solution Approach 1:

The roller-based mechanism with inclined ramps maintains continuous engagement between the rollers and the ramps during both forward and reverse movements. This continuous engagement eliminates the lost motion and idle time associated with traditional ratchets that require the pawl to disengage and re-engage, thereby reducing the loss of time during reverse rotation while maintaining torque transmission efficiency.

Inventive Principle:
Principle #20Continuity of useful 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

The wrench enables efficient unidirectional torque transmission with minimal reverse rotation, facilitating use in confined environments and reducing the need for excessive handle movement.

Implementation Method 1

Elastic members are interposed between the rollers and driven bodies to hold the rollers in wedging position between the ramps and cylindrical walls of the drive members

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

cylindrical rollers that engage ramps on driven bodies and cylindrical walls of drive members... hold the rollers in wedging position

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

A first wedging element is in engagement with a first ramp and inside cylindrical wall... A second wedging element is in engagement with a second ramp and the inside cylindrical wall... whereby angular movement of the handle in a clockwise direction transmits torque to the driven body

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 4

wedging elements to transmit torque... wedging engagement with the ramps and cylindrical wall

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 5

on movement of the handle in a counterclockwise direction the wedging elements are moved from the wedging engagement with the ramps and cylindrical wall of the head

Methodology Applied
Scientific EffectGeometry: Geometry

Data Source

PatentEP3980219B1wrench
Publication Date: 2025.10.01 YANG WEIKAI
  • EP3980219B1 patent drawingFigure 1~3
  • EP3980219B1 patent drawingFigure 4~5
  • EP3980219B1 patent drawingFigure 6~7

AI summary

A wrench (10) has a roller motion transmission mechanism that changes reciprocating motion of a driving member to unidirectional rotational motion of a driven member. The wrench (10) has a head (17) with a cylindrical inside wall (24) surrounding a body (18) with a plurality of ramps (48) inclined toward the cylindrical inside wall (24). A wedging member (53,54,55,56,57,58,59,60,61) comprising a cylindrical roller engages each ramp (48) and the cylindrical inside wall (24) of the head (17). A cage (52) anchored to the body (18) retains the wedging members (53,54,55,56,57,58,59,60,61) in contiguous locations relative to the ramps (48) and the cylindrical inside wall (24) of the head (17). Retainers (113,114,115,116,117,118,119,120) connected to the cage (52) bias all of the wedging members (53,54,55,56,57,58,59,60,61) into engagement with the ramps (48) and the cylindrical inside wall (24) of the head (17).