Motor Control Module with Electronic Clutch for Power Tool Overload Protection
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Solution Overview
Problem
Existing motor control systems for power tools require dedicated circuits for each application, lacking a unified solution for controlling and protecting motors across various tools, and do not effectively provide user feedback or prevent unintended startup after overload events.
Innovation Solution
A modular control system with a microprocessor and electronic clutch that includes methods for aural and tactile feedback, torque control, and overload protection, capable of configuring for different motors and tools, using soft-coded coefficients to enable or disable protection functions and prevent unintended startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated analog or digital control circuits are used for each motor application, then the motor control precision and reliability are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements a universal microcontroller-based control module that can control different types of motors (universal motors, capacitor-start motors, shaded-pole motors) across various power tool applications. The microcontroller executes different control algorithms and parameters depending on the specific motor type and application, replacing the need for dedicated control circuits for each motor. This multi-functional approach maintains reliability while reducing device complexity and manufacturing cost.
2Manufacturing precision
If multiple dedicated control circuits are used for different power tools, then the control precision for each specific application is improved, but the adaptability and versatility decrease
Solution Approach 1:
The control module employs dynamic configuration capabilities where the microcontroller can be programmed with different control algorithms, parameters, and protection thresholds depending on the specific power tool application. The system dynamically adapts its control strategy based on the motor type, load conditions, and desired performance characteristics, allowing a single hardware platform to achieve application-specific precision control across multiple tool types.
Solution Approach 2:
The patent utilizes programmable parameters including duty cycle, pulse width modulation (PWM) frequency, current thresholds, and protection settings that can be modified through software configuration. This allows the same control module hardware to be optimized for different motor types and power tool applications by changing control parameters rather than requiring different hardware circuits, thereby maintaining precision while improving adaptability.
3Reliability
If protection functions are always active to prevent overload damage, then the tool reliability is improved, but the productivity and ease of operation decrease due to frequent shutdowns
Solution Approach 1:
The control module implements graduated protection strategies rather than immediate complete shutdowns. When overload conditions are detected, the system first applies corrective actions such as reducing duty cycle, adjusting PWM parameters, or activating protection algorithms to bring the motor back within safe operating parameters. Only when these corrective actions fail to resolve the overload condition does the system initiate a shutdown, thereby maintaining productivity while still providing reliable protection.
Solution Approach 2:
The system continuously monitors motor current, temperature, and operational parameters, providing real-time feedback to the microcontroller. This feedback enables the control module to detect developing overload conditions and apply corrective measures before critical damage occurs, reducing the frequency of complete shutdowns while maintaining reliable protection. The feedback loop allows the system to adapt to changing load conditions and maintain optimal operation within safety boundaries.
Data Source
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AI summary
A motor control module designed to control operation of a plurality of different motors in a plurality of different tools a power tool uses an electronic clutch in the module in conjunction with a mechanical clutch in the tool to protect the tool against an overload event. The module is adapted to implement methods to provide aural and/or tactile feedback to a tool user as a warning of an impending or current fault condition in the tool. The module can prevent power from inadvertently turning on either after an overload event has cleared with the tool plugged in and its power switch on, or after plugging in the tool within the power switch on. The control module is adapted to provide torque control for the power tool, to estimate tool motor temperature and to inform a tool user when a servicing need in the tool is required.