Torque Limiting Ratchet Wrench Nested Shaft Design

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Solution Overview

Problem

Existing fastener-driving tools with elongate shafts are limited in the mechanisms they can employ due to the length and diameter constraints, which restrict their functionality, especially in tight spaces and when preventing damage to fasteners and substrates.

Innovation Solution

A fastener driving device with a torque limiting mechanism integrated within the elongate shaft, housing a ratcheting mechanism, allowing controlled torque application and reduced tool profile for use in tighter locations, while enabling effective fastener driving without excessive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mechanisms are positioned within the driving head of conventional tools, then the tool structure is simple, but the functionality is limited by the length and diameter of the elongate shaft

Engineering Contradiction:

ImprovefunctionalityVSAvoidtool structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The torque limiting mechanism and ratcheting mechanism are nested within the elongate shaft of the tool. The torque limiting mechanism is positioned inside the shaft, and the ratcheting mechanism is positioned within the torque limiting mechanism, creating a nested arrangement that enables multiple functions within the constrained shaft dimensions.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Force

If the tool applies high torque to drive fasteners, then fastening force is sufficient, but damage to the fastener and substrate may occur

Engineering Contradiction:

Improvefastening forceVSAvoiddamage to fastener and substrate

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The torque limiting mechanism changes the torque parameter by providing a predetermined torque limit. When the applied torque reaches this predetermined limit, the mechanism allows the driving head to rotate relative to the elongate shaft, thereby preventing torque from exceeding the safe threshold that could damage the fastener or substrate.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The torque limiting mechanism acts as an intermediary between the user's applied force and the fastener. It mediates the torque transmission by limiting the maximum torque that can be applied to the fastener, preventing direct transmission of excessive force that could cause damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If the tool is designed with a compact profile for tight spaces, then accessibility is improved, but the mechanisms available are restricted

Engineering Contradiction:

Improvetool profileVSAvoidmechanism availability

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The ratcheting mechanism is positioned within the torque limiting mechanism, creating a nested arrangement that reduces the overall tool profile. This nested configuration allows both mechanisms to function within a compact volume, enabling the tool to access tight spaces while maintaining multiple functions.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS11440169B2Torque limiting ratchet wrench

Publication Date: 2022.09.13 GAUTHIER BIOMEDICAL

AI summary

A fastener driving device including an elongate shaft extending between the driving head and the handle is provided that has a torque limiting mechanism disposed partially within the handle and extending through the elongate shaft into engagement with the driving head. The torque limiting mechanism enables the driving head to drive the fastener into the substrate without exerting more than a predetermined maximum torque on the fastener, thereby avoiding damage from being done to the fastener and/or the substrate. A ratcheting mechanism is disposed within a torque gear of the torque limiting mechanism to provide a ratcheting function to the tool with a small profile for the tool.