Electronic Clutch Torque Control via Current Threshold
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Solution Overview
Problem
Existing power tools with mechanical and electronic clutches face issues such as wear, bulkiness, weight, and complexity, along with inaccuracies in torque control, which affect their performance and user experience.
Innovation Solution
A power tool with an electronic clutch system that utilizes a controller, current sensing circuit, rotation sensing circuit, and clutch setting circuit to accurately manage torque transmission by adjusting current thresholds and rotational speed, allowing for precise interruption of power delivery to the motor, and incorporating a membrane potentiometer and Hall sensors for clutch setting and speed selection, providing a compact and reliable solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical clutch is used to interrupt power transmission when torque exceeds a threshold, then torque control is achieved, but the device adds excessive bulk and weight to the tool
Solution Approach 1:
The patent replaces the mechanical clutch system with an electronic control system that uses a torque sensor to detect torque levels and a controller to interrupt power transmission electronically when the torque threshold is exceeded, eliminating the need for heavy mechanical clutch components while maintaining torque control functionality
Solution Approach 2:
The patent extracts the essential function of torque control from the mechanical clutch system and implements it separately through electronic sensing and control circuits, removing the bulky mechanical components while preserving the torque interruption capability
2Reliability
If a mechanical clutch is used to interrupt power transmission, then torque control is achieved, but the components wear over time
Solution Approach 1:
The patent replaces the wear-prone mechanical clutch components with an electronic control system that uses electrical signals to interrupt power transmission, eliminating mechanical wear and significantly extending the operational lifespan of the torque control mechanism
Solution Approach 2:
The electronic control system continuously monitors torque through the torque sensor and automatically interrupts power transmission when thresholds are exceeded, providing self-regulating torque control without mechanical contact and wear
3Reliability
If existing electronic clutches are used to sense and interrupt power transmission, then torque control is achieved, but the system becomes overly complex
Solution Approach 1:
The patent combines the torque sensing function and the power transmission interruption function into a single integrated control system where the torque sensor directly interfaces with the controller, which in turn controls the power transmission path, simplifying the overall electronic architecture while maintaining accurate torque control
4Device complexity
If existing electronic clutches are used to sense and interrupt power transmission, then torque control is achieved, but the system becomes inaccurate
Solution Approach 1:
The patent implements a feedback control system where the torque sensor continuously monitors the actual torque being transmitted and provides real-time feedback to the controller, which adjusts power transmission to maintain accurate torque levels and interrupt transmission when thresholds are exceeded, significantly improving torque control precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The electronic clutch system offers high accuracy and reliability comparable to mechanical clutches without added weight or bulk, providing a compact, economical, and user-friendly power tool with efficient torque control.
Implementation Method 1
a membrane potentiometer engaged with the collar to output the clutch setting signal based upon a rotatable position of the collar
Implementation Method 2
a Hall sensor configured to determine rotational speed by counting revolutions of the motor during a given time period
Data Source
Figure 1A
Figure 1B
Figure 2~3
AI summary
A method is presented for controlling operation of a power tool having an electric motor drivably coupled to an output spindle. The method includes: receiving an input indicative of a clutch setting for an electronic clutch, where the clutch setting is selectable from a plurality of driver modes; setting the value of a maximum current threshold in accordance with the selected one of the plurality of driver modes; determining rotational speed of the electric motor; determining an amount of current being delivered to the electric motor; comparing the amount of current being delivered to the electric motor to the maximum current threshold; and interrupting transmission of torque to the output spindle when the amount of current being delivered to the electric motor exceeds the maximum current threshold and the rotational speed of the electric motor is decreasing.