Trigger Switch Anti-Conduction Mechanism for Arc Prevention
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Solution Overview
Problem
Existing trigger switches in power tools can continue to supply power to loads even when deactivated due to the formation of fibrous conductors between contacts, leading to unintended energy delivery.
Innovation Solution
Incorporating an anti-conduction portion that moves away from the contacts in the same direction as the trigger's pulling motion, ensuring complete power cutoff when the switch is deactivated, and utilizing a variable resistor to control motor speed based on trigger pull distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contacts are separated to stop power supply, then power cutoff is achieved, but arcs may form between the contacts creating fibrous conductors that continuously supply power to the load
Solution Approach 1:
The patent introduces an anti-conduction portion as an intermediary element positioned between the two contacts. This non-conductive component physically blocks the formation of arcs and fibrous conductors during contact separation, preventing the harmful effect while maintaining the power cutoff function. The anti-conduction portion moves with the trigger, dynamically maintaining its blocking position between the contacts throughout the triggering operation.
2Reliability
If an anti-conduction portion is added to prevent arc formation, then power cutoff reliability is improved, but the device complexity increases
Solution Approach 1:
The anti-conduction portion is merged with the trigger assembly, moving together as a single unit when the trigger is pulled. This integration approach adds the necessary protective function without requiring separate complex mechanisms. The anti-conduction portion is structurally combined with existing components, minimizing the increase in overall device complexity while achieving the desired power cutoff reliability.
3Device complexity
If the anti-conduction portion moves in the same direction as the trigger pull, then the structure is simplified, but the space required in the triggering direction increases
Solution Approach 1:
The anti-conduction portion is designed to extend in a direction substantially perpendicular to the trigger pulling direction. This dimensional reorientation allows the component to effectively block arcs between contacts while minimizing the increase in length along the trigger pulling axis. By utilizing the perpendicular dimension, the design achieves the necessary protective function with reduced impact on the overall trigger switch length.
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
Prevents the formation of arcs and fibrous conductors, ensuring reliable power cutoff and allowing for controlled motor speed adjustment, thereby enhancing the safety and functionality of the power tool.
Implementation Method 1
the separation of the contacts stops the supply of power to the load. However, depending on the separated distance, arcs may be produced between the contacts. Such arcs may form a fibrous conductor.
Implementation Method 2
utilizing a variable resistor to control motor speed based on trigger pull distance
Data Source
AI summary
A trigger switch (20) includes two contacts (25a, 25b), which are used to supply power to a load (16a), and an anti-conduction portion (26), which is arranged between the two contacts (25a, 25b) when the trigger switch (20) is deactivated. The anti-conduction portion (26) is moved away from between the two contacts (25a, 25b) when the trigger switch (20) is activated.