Impact Wrench Torque Estimation Using Angle and Energy Losses
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Solution Overview
Problem
Determining the actual torque applied by impact wrenches to fasteners is difficult and inaccurate, despite their advantages in compact size and low cost.
Innovation Solution
A power tool that estimates torque by measuring the angle of rotation and energy expended, accounting for energy efficiency and using various sensors to compensate for energy losses, with a controller determining the actual torque applied based on sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impact wrenches are used for tightening fasteners, then the tool achieves compact size and low cost, but the torque applied to fasteners cannot be accurately determined
Solution Approach 1:
The patent replaces direct mechanical torque measurement mechanisms with an electrical/electronic system that measures angle of rotation and energy expended, then calculates torque through controller processing. This substitution enables accurate torque determination in impact wrenches without adding complex mechanical measurement components.
Solution Approach 2:
The patent introduces sensors as intermediary devices that indirectly measure torque by detecting angle of rotation and energy consumption, rather than directly measuring torque force. The controller acts as another intermediary that processes these measurements to determine actual torque applied to the fastener.
2Measurement precision
If traditional torque measurement methods are used, then torque can be directly measured, but the tool size increases and cost increases
Solution Approach 1:
The patent replaces heavy mechanical torque measurement systems with lightweight electronic sensors and controller-based calculation methods. This substitution maintains torque measurement accuracy while significantly reducing tool weight and complexity.
Solution Approach 2:
The patent uses sensors to create electrical copies or representations of mechanical parameters (angle and energy), which are then processed to determine torque. This copying approach avoids the need for direct mechanical torque measurement hardware.
3Ease of manufacture
If impact wrenches are used, then compact size and low cost are achieved, but energy transfer efficiency varies making torque determination difficult
Solution Approach 1:
The patent implements a feedback system where sensors continuously monitor angle of rotation and energy expended, and the controller uses this feedback to calculate and determine the actual torque applied. This feedback mechanism compensates for varying energy transfer efficiency in impact wrenches.
Solution Approach 2:
The patent changes the measurement parameters from direct torque force measurement to measuring angle of rotation and energy expended, which are more easily and cheaply measurable parameters that can be used to calculate torque while accounting for energy transfer variations.
Data Source
AI summary
A power tool and method of controlling a motor of the power tool based on a determination of torque is provided. The method of determining torque uses the energy output by the drive mechanism and the angle of rotation of the output shaft to estimate torque. The energy is determined by subtracting efficiency losses (or gains) from a nominal energy of the drive mechanism in order to improve the torque estimation.