Non-Contact Speed Selector Switch for Rotary Power Tool Motors
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Solution Overview
Problem
Existing rotary power tools lack an efficient and contact-free method to adjust the rotational speed of motors, relying on movable conductors for speed selection which can be cumbersome and prone to electrical issues.
Innovation Solution
Incorporation of a non-contact speed selector switch using a Hall-effect sensor and a magnet within the power tool's housing, allowing for the adjustment of motor speed without electrical contact, enabling precise control through varying proximity detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If movable conductors are used for speed selection, then electrical connection is established, but the switch becomes cumbersome and prone to electrical issues
Solution Approach 1:
The patent replaces the traditional mechanical contact-based speed selector switch with a non-contact Hall effect sensor system. The Hall effect sensor detects the position of a magnet on the actuator shaft to determine speed settings without any physical electrical contact, thereby eliminating wear, sparking, and electrical connection issues while maintaining reliable operation.
Solution Approach 2:
The patent introduces a magnet as an intermediary element between the user's actuator manipulation and the Hall effect sensor's detection function. The magnet's movement relative to the sensor provides positional information for speed selection without requiring direct electrical contact, resolving the contradiction between reliability and ease of operation.
2Reliability
If non-contact Hall effect sensor is used, then contact-related issues are eliminated, but device complexity increases
Solution Approach 1:
The Hall effect sensor serves multiple functions within the speed selector switch: it detects actuator position, determines speed settings, and provides input to the controller. This multi-functionality reduces the need for separate components and simplifies the overall device structure despite introducing non-contact sensing technology.
Solution Approach 2:
The patent utilizes changes in magnetic field parameters (strength and position) as the actuator moves to different speed settings. The Hall effect sensor detects these parameter changes to determine the selected speed, providing a reliable non-contact measurement method that does not require complex mechanical structures.
3Device complexity
If traditional contact-based switch is used, then device structure is simple, but mechanical wear occurs
Solution Approach 1:
The patent replaces the mechanical contact-based switching mechanism with a magnetic field-based Hall effect sensor system. This substitution eliminates physical wear between contact surfaces while maintaining a relatively simple device structure, thereby extending the switch lifespan without significantly increasing 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
Enables seamless and reliable adjustment of motor speed, enhancing user experience by eliminating contact-related issues and providing precise control over rotational speeds without mechanical wear.
Implementation Method 1
In one aspect, a non-contact speed selector switch includes a Hall-effect sensor and an actuator
Data Source
AI summary
A rotary power tool includes a housing having a motor housing portion and a handle portion extending therefrom. An electric motor is positioned within the motor housing portion. The rotary power tool further includes a trigger switch configured to activate and deactivate the motor. The rotary power tool further includes a non-contact speed selector switch positioned in the housing. The non-contact speed selector switch is configured to adjust a rotational speed of the motor. The non-contact speed selector switch is separate from the trigger switch.