Impact Tool Motor Current Sensing for Precise Impact Detection
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Solution Overview
Problem
Existing electric power tools lack an effective means to determine whether the impact mechanism is performing an impact operation, which can lead to inefficient control and potential excessive force application.
Innovation Solution
Incorporating an impact detecting unit that measures and analyzes the d-axis and q-axis currents supplied to the electric motor to determine if an impact operation is occurring, allowing for adaptive control gain adjustments and precise motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If no impact detection means is provided, then the device structure remains simple, but the control precision and ability to prevent excessive force are insufficient
Solution Approach 1:
The patent replaces mechanical impact detection mechanisms with electrical current measurement. The impact detecting unit uses d-axis and q-axis current measurements from the motor control system to detect impact operations, eliminating the need for separate mechanical sensors while achieving precise detection.
Solution Approach 2:
The patent uses motor current as an intermediary to detect impact operations. Instead of directly measuring impact force or using separate sensors, the system detects changes in motor current characteristics (d-axis and q-axis components) that occur during impact operations, providing indirect but effective detection.
2Reliability
If impact detection is implemented using traditional methods, then detection capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent makes the motor control system serve multiple functions: it not only controls motor operation but also detects impact operations through current measurement. The existing d-axis and q-axis current measurement infrastructure is utilized for both motor control and impact detection, eliminating the need for dedicated detection hardware.
Solution Approach 2:
The motor control system performs self-diagnosis by monitoring its own current characteristics to detect impact operations. The control unit analyzes the d-axis and q-axis current measurements that are already being taken for motor control purposes, allowing the system to detect impacts without additional external measurement devices.
Data Source
AI summary
An electric power tool includes an electric motor (AC motor), an impact mechanism, an impact detecting unit, and a measuring unit. The impact mechanism performs an impact operation that generates impacting force by receiving motive power from the electric motor. The impact detecting unit determines whether or not the impact operation is being performed. The measuring unit measures at least one of a d-axis current or a q-axis current, each of which is supplied to the electric motor. The impact detecting unit determines, based on at least one of a measured value (current measured value) of the d-axis current or a measured value (current measured value) of the q-axis current, whether or not the impact operation is being performed. The measured values (current measured values) of the d-axis current and the q-axis current have been obtained by the measuring unit.