Kickback Detection in Electric Power Tools Using Acceleration Sensors
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Solution Overview
Problem
Conventional electric power tools misdetect kickback events due to relying on motor rotation speed changes, leading to unnecessary motor shutdown and user discomfort.
Innovation Solution
An electric power tool with a detector and kickback determiner that assesses attitude changes, such as movement speed and acceleration, to accurately determine kickback occurrences, thereby reducing misdetection and ensuring appropriate motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If kickback detection is based on motor rotation speed change rate, then the detection system is simple, but the detection accuracy is low leading to misdetection
Solution Approach 1:
The patent replaces the electrical measurement method (motor rotation speed detection) with a mechanical sensing method (acceleration sensor detecting main body movement). The acceleration sensor directly measures the physical movement of the tool main body during kickback, providing more accurate detection by measuring the actual mechanical response rather than inferring from motor electrical characteristics.
Solution Approach 2:
The patent introduces the acceleration sensor as an intermediary device that directly detects the kickback event through physical movement measurement. This intermediary provides a more direct and accurate measurement path between the kickback event and the detection system, eliminating the indirect inference through motor speed changes.
2Speed
If kickback detection is based on motor rotation speed changes, then the response is immediate, but unnecessary motor shutdown occurs due to misdetection
Solution Approach 1:
The patent replaces electrical signal-based detection with direct mechanical movement detection using an acceleration sensor. This provides more reliable differentiation between actual kickback events and normal operational variations, reducing false alarms while maintaining immediate response capability.
3Measurement precision
If the detection system uses acceleration sensor to measure main body movement, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The acceleration sensor serves as a compact intermediary device that directly measures kickback acceleration. This single sensor component provides accurate detection without requiring complex measurement systems, achieving high precision with minimal added complexity.
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
Improved accuracy in kickback detection reduces unnecessary motor shutdowns, enhancing user experience and preventing damage by accurately determining when a kickback has occurred.
Implementation Method 1
The detector may comprise an acceleration sensor configured to detect an acceleration of the main body in the at least one axis direction
Implementation Method 2
The detector may comprise an angular speed sensor configured to detect an angular speed of the main body around the at least one axis of the main body
Data Source
AI summary
An electric power tool in one aspect of the present disclosure comprises a main body, a motor, a driver, a detector, and a kickback determiner. The kickback determiner determines that the main body is kicked back from a workpiece when an attitude change amount of the main body detected by the detector exceeds a preset kickback determination threshold during driving of the motor by the driver.