Power Tool Speed Selector Using Hall Sensor Feedback

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Solution Overview

Problem

Existing power tools lack efficient mechanisms to seamlessly transition between low speed high torque and high speed low torque modes, particularly in core drills, which affects their versatility and performance with different bit sizes.

Innovation Solution

A power tool incorporating a transmission shiftable between low speed high torque and high speed low torque modes, with an electro-mechanical speed switch using a magnet and Hall Effect sensor to electronically adjust motor speed without changing gear ratios, allowing for multiple speed settings optimized for various bit sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mechanical gear changes are used to transition between low speed high torque and high speed low torque modes, then speed and torque modes can be changed, but the device complexity increases and seamless transition is difficult to achieve

Engineering Contradiction:

Improvespeed mode transition capabilityVSAvoidtransmission mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical gear shifting mechanism with an electro-mechanical system. A motor-driven actuator moves a shift collar along a guide rail to engage different gears, while a Hall effect sensor detects the gear position and feeds back to a controller that adjusts motor speed electronically. This substitution reduces mechanical complexity and enables seamless transitions between speed and torque modes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If multiple mechanical gears are used to provide different speed settings, then speed versatility is improved, but the device complexity and loss of time for gear shifting increase

Engineering Contradiction:

Improvespeed setting optionsVSAvoidtime for gear shifting

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements dynamic speed control where the motor speed is continuously adjusted based on the detected gear position. The Hall effect sensor real-time monitors the shift collar position, and the controller dynamically modifies motor operating parameters to optimize performance for each gear setting. This dynamic adjustment eliminates the need for manual gear shifting and reduces time loss.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent incorporates a Hall effect sensor that detects the position of the shift collar and provides feedback to the controller. This feedback mechanism enables the system to automatically adjust motor speed according to the engaged gear, ensuring optimal performance without requiring manual intervention or causing time loss during transitions.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If traditional mechanical speed switches are used, then speed control is achieved, but the manufacturing precision and reliability are reduced

Engineering Contradiction:

Improvespeed control capabilityVSAvoidspeed setting precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces traditional mechanical speed switches with an electro-mechanical system using a Hall effect sensor. This sensor provides non-contact detection of gear position, eliminating wear and precision issues associated with mechanical switches. The electronic control system then precisely adjusts motor speed based on the detected position, achieving high manufacturing precision and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution provides a power tool with optimized speed settings for different bit sizes, enhancing versatility and performance by electronically adjusting motor speed through a magnet and Hall Effect sensor, without mechanical gear changes.

Implementation Method 1

Methodology Applied

Scientific EffectHall Effect: Hall Effect

Data Source

PatentUS20250236005A1Power tool with electro-mechanical speed select switch

Publication Date: 2025.07.24 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A power tool includes a housing, a motor supported within the housing, a transmission operatively coupled to the motor, the transmission shiftable between a low speed high torque mode and a high speed low torque mode, a spindle configured to receive torque from the motor through the transmission, a speed selector including an actuator movable to shift the transmission between the low speed high torque mode and the high speed low torque mode, a shaft movable in response to movement of the actuator, a magnet coupled to the shaft, and a controller configured to vary an operating speed of the motor based on a detected position of the magnet.