Motion-Sensing Power Tool Shutdown for Inactivity Safety
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Solution Overview
Problem
Electric power tools, such as chainsaws and hedge cutters, pose safety risks when left unattended in an active state, as they may not be easily identifiable as operational, leading to potential accidental activation and injury, and existing solutions like LED indicators or inactivity timers are inadequate, particularly for untrained users or when the tool is carried for later use.
Innovation Solution
Incorporating a movement sensor, like an accelerometer, into the power tool to detect absence of movement and disable the driving mechanism after a predetermined time period, ensuring the tool remains inactive when not in use, thereby preventing accidental activation while allowing for safe handling and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If an LED or light indicator is used to show active state, then the active state is indicated, but the indicator is difficult to see and understand, especially for untrained users
Solution Approach 1:
The patent replaces visual indicators (LED lights) with a mechanical/tactile indicator system. The tool generates vibrations when active, which can be felt by the user and nearby persons. This substitution from optical to mechanical sensing makes the active state more perceptible and understandable, especially for children or untrained users who can easily distinguish vibration from no vibration.
2Reliability
If the power tool is switched off after a time period of inactivity, then safety is improved, but the tool may be switched off when carried around for later use
Solution Approach 1:
The patent introduces dynamic motion detection capabilities to distinguish between different states of the tool. The motion sensor detects whether the tool is being carried (motion present) or left stationary (no motion). The system dynamically adjusts its behavior: when motion is detected, the tool remains active; when no motion is detected for a predetermined period, the tool switches off. This dynamic approach resolves the contradiction by adapting the safety mechanism to the actual usage context.
3Reliability
If a motion sensor is used to detect absence of movement, then the tool can distinguish between carrying and leaving, but the device complexity increases
Solution Approach 1:
The patent makes the motion sensor serve multiple functions: it detects both the presence/absence of motion (to distinguish carrying from leaving) and generates vibrations (as an active state indicator). By making the motion detection system multi-functional, the patent avoids adding separate components for each function, thereby minimizing the increase in device complexity while maintaining high reliability in detecting usage state.
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
This solution effectively prevents unattended power tools from being accidentally activated, enhancing safety and usability by distinguishing between active use and inactivity, ensuring the tool remains off when not in use without disrupting normal operation.
Implementation Method 1
Incorporating a movement sensor, like an accelerometer, into the power tool to detect absence of movement
Data Source
AI summary
A power tool (100), such as a chainsaw, comprising means (230) for driving said power tool (100) and a controller (210). The power tool comprises a movement sensor (220) and the controller (210) is configured to receive a signal from said movement sensor (220), determine if said signal is a signal indicating a movement, determine a time wherein no signal indicating a movement is received, determine if said time exceeds a time period, and if so, disable said driving means (230).