Non-Contact Trigger Sensing for Precise Power Tool Actuation
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Solution Overview
Problem
Existing power tools lack efficient mechanisms for accurately sensing the position of the trigger, which is crucial for initiating firing operations reliably.
Innovation Solution
The power tools incorporate various sensors such as Hall effect sensors, inductive sensors, and tunnel magnetoresistance (TMR) sensors to detect the position of the trigger based on magnetic flux, induced current, or resistance changes, and an electronic controller to interpret these signals and control the drive mechanism accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional contact-based switch mechanisms are used to detect trigger position, then the device complexity is reduced, but the measurement precision and reliability of trigger position detection deteriorates
Solution Approach 1:
The patent replaces traditional mechanical contact-based switch mechanisms with non-contact magnetic sensors (Hall effect sensors, TMR sensors) to detect trigger position. This substitution eliminates mechanical wear and contact resistance issues while providing more precise and reliable position detection through magnetic field sensing, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the trigger and the sensor system. A magnet attached to the trigger interacts with the magnetic field, and the sensors detect changes in this field to determine trigger position. This intermediary approach enables non-contact detection with high precision while maintaining relatively simple device architecture.
2Reliability
If non-contact magnetic sensors are used to detect trigger position, then the reliability of firing operation initiation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates magnets and sensors during the assembly process rather than requiring post-assembly calibration. The magnetic components are pre-positioned on the trigger and the sensors are pre-mounted on the housing, ensuring correct alignment before the tool is put into service. This preliminary action approach maintains reliability while reducing the impact of manufacturing tolerances.
Solution Approach 2:
The magnetic field-based detection system is inherently self-aligning to a degree, as the magnetic interaction occurs throughout the detection range rather than requiring precise point-to-point alignment. The system automatically compensates for minor manufacturing variations in sensor and magnet positioning, maintaining reliable operation without requiring high-precision manufacturing.
3Adaptability or versatility
If multiple sensor types (Hall effect, inductive, TMR) are implemented, then the adaptability of the power tool to different trigger designs is improved, but the device complexity increases
Solution Approach 1:
The patent describes a sensor system architecture that can accommodate multiple sensor types (Hall effect sensors, inductive sensors, TMR sensors) through a unified control approach. The electronic controller is designed to work with different sensor technologies, allowing the same basic system design to be adapted to various trigger configurations and magnetic component arrangements, thereby achieving universality across different power tool applications.
Solution Approach 2:
The patent leverages the different operating characteristics of various sensor types to optimize performance for specific applications. Hall effect sensors operate based on magnetic flux density, TMR sensors provide higher sensitivity with lower power consumption, and inductive sensors offer robustness for metal-environment applications. By selecting and tuning sensor parameters according to the specific trigger design requirements, the system achieves high adaptability while managing complexity through parameter optimization rather than architectural 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
This solution enables precise and reliable detection of the trigger position, ensuring consistent and accurate initiation of firing operations in power tools, enhancing their performance and user experience.
Implementation Method 1
a Hall effect sensor configured to sense a position of the trigger based on a proximity of the magnet to the Hall effect sensor
Implementation Method 2
an inductive sensor is configured to sense a position of the trigger based on a voltage produced in the sensor by the metal target portion
Implementation Method 3
The TMR sensor is configured to sense a position of the trigger based on a signal produced by the TMR sensor related to a position of the magnet
Data Source
AI summary
A power tool including a housing, a trigger disposed on an outside of the housing, the trigger including a magnet, a motor within the housing, the motor configured to produce a rotational output to a drive mechanism, a Hall effect sensor configured to sense a position of the trigger based on a proximity of the magnet to the Hall effect sensor, and an electronic controller connected to the Hall effect sensor. The electronic controller is configured to determine the position of the trigger based on a signal from the Hall effect sensor and control the drive mechanism based on the position of the trigger.