Dual Torque Transducer Power Tool for Precise Screw Joint Tightening
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Solution Overview
Problem
Existing electric power tools face challenges in accurately monitoring and delivering torque due to variations caused by friction in joints and unpredictable gear ripple, leading to inaccuracies and a need for improved precision and service detection.
Innovation Solution
The electric power tool incorporates both a back torque transducer and a front torque transducer, positioned on either side of the angle gear, to provide more accurate torque measurement and detection, allowing for precise output torque delivery and service monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single torque transducer is used to monitor torque, then the device complexity is reduced, but the measurement precision deteriorates due to unpredictable gear ripple and friction variations
Solution Approach 1:
The torque measurement function is segmented into two separate measurement points: a front torque transducer measuring torque after the output bevel gear, and a back torque transducer measuring torque before the input bevel gear. This segmentation allows independent measurement of torque at different stages, enabling the system to account for gear ripple effects and friction variations that would otherwise compromise single-point measurement accuracy.
2Reliability
If torque monitoring is implemented to verify joint fastening, then the reliability of joint fastening is improved, but the measurement precision deteriorates due to friction losses and gear ripple in the power tool
Solution Approach 1:
The system implements feedback by continuously monitoring torque at both front and back measurement points and comparing the values. The controller uses this feedback to detect deviations caused by gear ripple and friction, allowing real-time compensation and verification that the joint is being fastened to the correct torque specification despite internal tool variations.
3Measurement precision
If the electric power tool condition deteriorates, then the device complexity remains the same, but the measurement precision worsens due to increased gear ripple
Solution Approach 1:
The system performs preliminary action by establishing a baseline relationship between front and back torque measurements when the tool is in good condition. During operation, it continuously compares current measurements against this baseline, enabling early detection of tool degradation such as increased gear ripple. This allows proactive service scheduling before measurement precision deteriorates beyond acceptable limits.
Data Source
AI summary
An electric power tool for tightening screw joints includes a housing that encloses an electric motor, an angle gear, a back torque transducer, and a front torque transducer. The angle gear includes an input bevel gear drivingly connected to the electric motor and an output bevel gear drivingly connected to an output shaft of the electric power tool. The back torque transducer is arranged to measure a back torque reaction value before the input bevel gear. And the front torque transducer is arranged to measure a front torque reaction value after the output bevel gear.