Power Tool Motor Control for Adaptive Impact and Unscrewing
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Solution Overview
Problem
Existing methods for controlling electric motors in power tools are inefficient and lack adaptability to specific tool conditions, leading to potential damage or improper operation due to unsuitable torque and speed settings.
Innovation Solution
The method involves detecting parameters such as motor current and rotational speed during impact operations to determine a drive time, adjusting torque or speed accordingly, and using a clutch or switching off the motor when necessary, with battery voltage compensation and operator-defined settings to prevent over-torque or over-driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electric motor is controlled with predetermined speed or torque based on switch actuation, then the control is simple, but the adaptability to specific tool conditions is poor
Solution Approach 1:
The control unit detects operating parameters (current, rotational speed) during impact operation and uses this feedback to automatically determine drive time and adjust motor control, replacing predetermined fixed control with adaptive control based on real-time tool conditions
Solution Approach 2:
The system automatically determines drive time and adjusts control parameters based on detected operating parameters without requiring manual intervention or complex external control systems, making the tool self-adjusting to its operating conditions
2Productivity
If the electric motor is operated with high torque and speed, then the productivity is improved, but the risk of damage to tool or workpiece increases
Solution Approach 1:
The motor operates in periodic impact pulses rather than continuous operation, with drive time automatically determined based on detected parameters. This periodic operation allows high power delivery during impact while preventing continuous overheating and damage to tool or workpiece
Solution Approach 2:
The control system dynamically adjusts drive time and operational parameters based on real-time detection of current and rotational speed, automatically adapting the motor operation to prevent damage while maintaining productivity
3Manufacturing precision
If the drive time is extended to ensure proper fastening, then the fastening quality is improved, but the risk of over-driving and damage increases
Solution Approach 1:
The control unit continuously detects operating parameters during the fastening process and uses this feedback to automatically determine when to terminate drive operation, preventing both insufficient fastening and over-driving damage through real-time parameter monitoring
Data Source
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AI summary
The application relates to a method for controlling an electric motor of a power tool with a tool holder, wherein at least one current of the electric motor and/or one rotational speed of the electric motor is recorded as a parameter during impact operation of the electric motor, and wherein a drive time of the electric motor for impact operation is determined depending on the parameter. Furthermore, the application relates to a method for controlling an electric motor of a power tool with a tool holder for unscrewing a screw from a counterpart, wherein, when unscrewing a screw, the electric motor is stopped if the torque delivered by the electric motor falls below a predetermined limit value, or if the screw has been unscrewed a predetermined number of revolutions from a seated position.Furthermore, the application relates to a method for controlling an electric motor of an electric tool with a holder for a tool for unscrewing a screw from a counterpart, wherein different control methods are used to unscrew the screw depending on a seating torque of the screw.