Telescopic Power Wrench Position Sensing for Fastener Length Control

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Solution Overview

Problem

Existing repositionable power wrenches face challenges in accurately monitoring the length of fasteners during tightening operations, leading to potential damage from incorrect contact or incomplete tightening due to axial movement and varying fastener lengths.

Innovation Solution

A repositionable power wrench with a telescopically arranged output shaft and a sensor system that monitors the level of extension, allowing precise control and detection of the output end's position, enabling adaptive movement and preventing incorrect fastener engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a telescopic output shaft is used to accommodate axial movement and varying fastener lengths, then adaptability to different fastener positions is improved, but the ability to accurately monitor fastener length is worsened

Engineering Contradiction:

Improveadaptability to different fastener positionsVSAvoidfastener length monitoring accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

A sensor is integrated into the telescopic output shaft to detect the axial position of the shaft in real-time during the tightening operation. This feedback signal is transmitted to a control unit that calculates the fastener length based on the sensor data, enabling accurate monitoring despite the shaft's movement and adaptation to varying fastener positions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The mechanical telescopic output shaft system is combined with an electronic sensing system. Instead of relying solely on mechanical contact or vibration analysis, the patent uses a sensor to detect the shaft's axial position and a control unit to process this information, replacing purely mechanical monitoring methods with an electromechanical system that provides more accurate and reliable fastener length measurement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the output shaft is in butt contact with the screw to monitor position, then position monitoring capability is improved, but the risk of damaging the screw, threads, or joint is worsened

Engineering Contradiction:

Improveposition monitoring capabilityVSAvoiddamage to screw, threads, or joint

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A sensor acts as an intermediary between the output shaft and the fastener monitoring function. The sensor detects the axial position of the telescopic shaft without requiring direct mechanical contact between the shaft and the fastener, eliminating the risk of damage while enabling precise position monitoring through non-contact or minimal-contact sensing

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If vibration analysis is used to estimate fastener length, then measurement capability is improved, but the reliability of length determination is worsened

Engineering Contradiction:

Improvefastener length estimation capabilityVSAvoidreliability of length determination

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces vibration analysis methods with a direct sensing approach. A sensor mounted on the telescopic output shaft directly measures the axial position of the shaft during the tightening operation, providing reliable and accurate fastener length determination without the ambiguities and reliability issues associated with vibration-based estimation methods

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

Ensures gentle and precise contact with fasteners, allowing for reliable monitoring and control of the tightening process, preventing damage and ensuring correct fastener length verification before completion.

Implementation Method 1

A resilient member is arranged to urge the output shaft towards the fully extended position

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11097386B2Power tool with position control

Publication Date: 2021.08.24 ATLAS COPCO IND TECHNIQUE AB INTELLECTUAL PROPERTY DEPARTMENT

AI summary

A repositionable power wrench includes a housing, a motor arranged inside the housing, and an output shaft, which is rotationally connected to the motor and telescopically arranged with respect to the housing to allow axial movement of the output shaft with respect to the housing between a fully extended position (Emax) and a fully compressed position, with a resilient member being arranged to urge the output shaft towards the fully extended position (Emax). The power wrench also includes or is connectable to a positioning system arranged to monitor a position of the power wrench. The output shaft includes an output end arranged to interact with a fastener. A sensor is arranged to monitor a level of extension (E) of the output shaft with respect to the housing, such that the position of the output end of the output shaft may be determined.