Electronic Clutch Braking for Power Tool Speed Drop Protection

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Solution Overview

Problem

Existing power tools lack efficient control mechanisms for managing motor speed and torque, particularly in situations where load conditions change rapidly, leading to inefficiencies and potential damage.

Innovation Solution

The implementation of an electronic clutch system with a controller that monitors motor speed and torque, activates the clutch to brake the motor when a speed drop threshold is reached, and adjusts power delivery based on torque and speed commands, using sensors for real-time feedback to optimize motor operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electronic clutch system is implemented to control motor speed and torque, then operational efficiency and damage prevention are improved, but device complexity increases

Engineering Contradiction:
Improvedamage preventionVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical clutch mechanisms with an electronic control system that uses sensors and a controller to monitor motor speed and torque, activating electromagnetic braking when thresholds are exceeded. This substitution eliminates complex mechanical linkages while achieving the same protective function through electronic sensing and control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously monitors motor speed and torque through sensors and compares readings against predetermined thresholds. When the speed drop threshold is exceeded within a specified time period, the controller activates the electronic clutch to apply braking force. This closed-loop feedback mechanism provides reliable protection while maintaining a relatively simple system architecture.

Inventive Principle:
Principle #23Feedback

2Reliability

If the electronic clutch activates to brake the motor when speed drop threshold is reached, then motor protection is improved, but operational time is reduced

Engineering Contradiction:
Improvemotor protectionVSAvoidmotor operation time
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The electronic clutch activates only when necessary - specifically when the motor speed drops by more than a predetermined threshold within a specified time period. This partial action approach applies braking force selectively rather than continuously, protecting the motor from damage while minimizing interruption to normal operation. The system allows full operation during normal conditions and intervenes only when protection is needed.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If real-time monitoring of motor speed and torque is implemented, then control precision is improved, but device complexity increases

Engineering Contradiction:
Improvespeed and torque monitoring accuracyVSAvoidsensor and controller complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The controller performs multiple functions: it monitors both speed and torque through sensor inputs, compares readings against thresholds, determines when clutch activation is necessary, and controls the electronic clutch actuator. This multi-functionality consolidates what could be separate complex systems into a single integrated controller, achieving precise monitoring while managing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4260983A1Electronic clutch for power tools
Publication Date: 2023.10.18 MILWAUKEE ELECTRIC TOOL CORP
  • EP4260983A1 patent drawingFigure 1
  • EP4260983A1 patent drawingFigure 2
  • EP4260983A1 patent drawingFigure 3

AI summary

Systems and methods for electronically limiting torque in a power tool. One power tool includes a motor, a trigger, and a controller connected to the trigger and the motor. The controller is configured to provide, in response to actuation of the trigger, power to the motor, determine a speed of the motor, activate the electronic clutch, in response to determining that the speed of the motor has dropped by the speed drop threshold within the first period of time, to electronically brake the motor for a second period of time, and provide, in response to the second period of time having passed, power to the motor.