Power Tool Motor Control for Impact Torque and Driving Time
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Solution Overview
Problem
Conventional electric motor control methods for power tools lack precision and efficiency, particularly in impact operating modes, leading to suboptimal performance and potential tool damage due to inadequate torque and rotation speed management, especially with variable battery voltage and unscrewing operations.
Innovation Solution
The method involves detecting current and rotation speed parameters during impact modes, specifying driving times based on these parameters, and adjusting torque and rotation speed accordingly, with features like clutch engagement, motor shutdown, and notification for low battery voltage to ensure precise control and prevent tool damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electric motor control methods are used with predefined rotation speed or torque, then the control is simple to implement, but the performance is suboptimal and tool damage may occur due to inadequate torque and rotation speed management
Solution Approach 1:
The control device detects current and rotation speed parameters during impact modes and uses this feedback to specify driving times and adjust torque and rotation speed dynamically, resolving the contradiction by implementing adaptive control that improves performance while maintaining reasonable system complexity
Solution Approach 2:
The patent transitions from static predefined control parameters to dynamic parameter adjustment based on real-time detection of current and rotation speed, allowing the system to adapt torque and rotation speed during operation to optimize performance without excessive complexity
2Productivity
If high torque and rotation speed are maintained during impact operating mode, then productivity is improved, but tool damage may occur due to excessive driving time
Solution Approach 1:
The control device implements periodic operation by alternating between impact modes with high torque and rotation speed for screw tightening and phases where torque is reduced or the motor is shut off, preventing tool damage while maintaining productivity through rhythmic high-performance intervals
Solution Approach 2:
The control device specifies a driving time for impact mode operation before tool damage can occur, proactively limiting the duration of high-stress operation to prevent damage while maximizing productive work time
3Manufacturing precision
If the electric motor is operated continuously without monitoring, then the operation is simple, but precision control of torque and rotation speed cannot be achieved
Solution Approach 1:
The control device monitors current and rotation speed parameters and uses this information to precisely control torque and rotation speed during impact modes, achieving precision control through feedback-based adaptive adjustment without excessive monitoring complexity
Solution Approach 2:
The patent replaces complex mechanical torque and speed control mechanisms with electronic detection and control of current and rotation speed parameters, achieving precision control through electrical monitoring and digital control algorithms
4Adaptability or versatility
If the electric motor is controlled with fixed parameters, then the control system is simple, but adaptability to variable battery voltage and different operating conditions is poor
Solution Approach 1:
The control system transitions from fixed parameters to dynamic parameter adjustment based on detected current and rotation speed, enabling adaptation to variable battery voltage and different operating conditions through real-time parameter optimization
Solution Approach 2:
The control device changes operational parameters such as driving time, torque, and rotation speed based on detected conditions including battery voltage variations, achieving adaptability through parameter optimization without excessive system complexity
Data Source
AI summary
A method for controlling an electric motor of a power tool having a receptacle for a tool, at least a current of the electric motor and/or a rotation speed of the electric motor during an impact operating mode of the electric motor being detected as a parameter, a driving time of the electric motor for the impact operating mode being specified as a function of the detected parameter. A method is also described for controlling an electric motor of a power tool having a receptacle for a tool for unscrewing a screw from a mating part.