Hand-held Power Tool Control Method for Drilling and Chiseling Modes
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Solution Overview
Problem
Hand-held power tools face challenges in distinguishing between controlled and uncontrolled rotary motions, leading to unnecessary triggering of safety functions during chiseling operations, which disrupts the user's intended mode of operation.
Innovation Solution
A control method that detects both rotary motion about the working axis and pivoting motion about a transverse axis to differentiate between drilling and chiseling modes, triggering a safety function only when the rotary motion exceeds a limiting value during drilling, while suppressing it during chiseling by monitoring angular velocities and using a protective device with a brake system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety function is triggered when rotary motion about the working axis exceeds a limiting value, then user safety is improved, but the safety function is undesirably triggered during controlled chiseling operations
Solution Approach 1:
The detection of rotary motion is segmented into two independent components: rotation about the working axis and pivoting about the transverse axis. By separately monitoring these two motion types, the system can distinguish between drilling operations (rotation about working axis) and chiseling operations (pivoting about transverse axis), thereby triggering the safety function only when appropriate without disrupting legitimate chiseling work
Solution Approach 2:
The pivoting motion about the transverse axis serves as an intermediary indicator to differentiate between drilling and chiseling modes. When pivoting motion exceeds a threshold, it acts as a mediator signal to suppress the safety function, preventing false triggering during chiseling while still allowing the safety function to operate during drilling operations
Data Source
AI summary
A control method is provided for a hand-held power tool (1), which includes a motor (5) for rotationally driving a tool holder (2) about a working axis (12), including the following steps: detecting a rotary motion of the hand-held power tool (1) about the working axis (12); detecting a rotary or pivoting motion about a transverse axis (18) extending transversely to the working axis (12); triggering a safety function for reducing the torque output of the motor (5) when the rotary motion about the working axis (12) exceeds a limiting value, and suppressing the safety function when the rotary or pivoting motion about the transverse axis (18) is greater than a threshold value.