Power Tool Handle Rotation Detection and Torque Control
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Solution Overview
Problem
Drill hammers pose a hazardous situation when the drill bit jams, causing sudden high torque that can injure the user, and existing solutions fail to differentiate between intentional and unintentional handle rotations, leading to unnecessary tool shutdown during comfortable holding position changes.
Innovation Solution
A control method for power tools that continuously monitors handle rotations using motion sensors and band-limited integrators to estimate rotational angles, activating a protective measure by reducing torque output when certain thresholds are exceeded, distinguishing between controlled and uncontrolled movements based on power consumption and torque criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the drill hammer is switched off when the handle rotates, then user injury is prevented, but intentional handle adjustments for comfortable holding position are interrupted
Solution Approach 1:
The system dynamically adjusts its response based on the characteristics of handle rotation. By monitoring rotational speed and acceleration, the control system distinguishes between rapid unintentional rotations (caused by bit jamming) and slow intentional adjustments, applying protective measures only when necessary
Solution Approach 2:
The system changes the parameter thresholds for triggering protective measures based on rotational characteristics. By setting different angular velocity thresholds and acceleration limits, the system adapts its sensitivity to differentiate between harmful and benign rotations
2Object-affected harmful factors
If the protective measure activates for any handle rotation, then user safety is improved, but tool availability and productivity deteriorate due to unnecessary shutdowns
Solution Approach 1:
The system continuously monitors handle rotation characteristics and provides feedback to the control unit. This real-time feedback enables the system to make informed decisions about when to activate protective measures, avoiding unnecessary shutdowns while maintaining safety
Solution Approach 2:
The patent replaces simple mechanical rotation detection with electronic sensing using motion sensors and band-limited integrators. This substitution enables more sophisticated analysis of rotation characteristics, allowing the system to distinguish between harmful and intentional rotations with greater accuracy
3Measurement precision
If the angular velocity threshold is set low, then sensitivity to rapid rotations is improved, but false activation during intentional slow rotations increases
Solution Approach 1:
The system performs preliminary analysis of rotation characteristics before activating protective measures. By evaluating both angular velocity and rotational acceleration, the system prepares to activate protection only when the pattern matches unintentional rotation, reducing false positives
Data Source
AI summary
A control method for a power tool for rotary tools comprises rotating a tool holder continuously about a working axis by a rotary drive. A rotary movement of a handle about the working axis is sensed by a motion sensor. A first angle of rotation of the handle is estimated by a first motion estimator, wherein rotary movements beneath a limit value are discounted. A second angle of rotation of the handle is estimated by a second motion estimator, wherein rotary movements beneath the limit value are taken into account. A measure for reducing the torque output of the rotary drive is activated when the first angle of rotation exceeds a first triggering threshold (A1), and when the second angle of rotation exceeds a second triggering threshold (A2) and at the same time a power output of the rotary drive exceeds a power threshold (L).