Pruning Shears Dual Trigger Detection Motor Control

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Solution Overview

Problem

Conventional battery-powered pruning shears lack efficient control mechanisms to manage motor operation, leading to potential noise interference and inefficient energy use, particularly when switching between cutting speeds and branch sizes.

Innovation Solution

The pruning shears incorporate a dual detection system using a primary trigger movement detector and a redundant trigger movement detector, along with a motor control unit that receives signals from a trigger potentiometer and a trigger hall sensor to optimize motor operation based on trigger movement, preventing noise-related issues and enhancing energy efficiency by adjusting cutting speed and distance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single trigger detector is used to control motor operation, then the device complexity is reduced, but noise interference may cause incorrect motor activation

Engineering Contradiction:

Improvemotor control accuracyVSAvoidtrigger detection system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a redundant trigger detection system with multiple detectors (potentiometer and hall sensor) that cross-validate each other before triggering motor operation. This beforehand verification cushioning prevents noise-induced false activations by requiring consistent signals from multiple independent detection mechanisms before the motor is activated.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If the motor operates at high speed continuously, then the productivity is improved, but the energy consumption increases and battery life decreases

Engineering Contradiction:

Improvecutting speedVSAvoidbattery consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic motor speed control based on actual operational needs. The motor control unit adjusts the motor speed between high and low states based on trigger activation patterns and load conditions, allowing the system to operate at high productivity when needed while conserving energy during lighter tasks or transitions, thereby optimizing the balance between cutting speed and battery consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs periodic motor operation rather than continuous high-speed running. The motor is activated in periodic bursts corresponding to actual cutting cycles, with idle periods in between where the motor remains inactive or at standby mode. This periodic action pattern maintains high productivity during active cutting while significantly reducing average energy consumption and extending battery life.

Inventive Principle:

Principle #19Periodic action

3Ease of operation

If the motor operates without precise control, then the ease of operation is improved, but noise interference causes incorrect operation

Engineering Contradiction:

Improvetrigger responseVSAvoidnoise interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback-based trigger detection system where multiple detectors continuously monitor trigger position and send signals to the motor control unit. The system cross-validates signals from the potentiometer and hall sensor, providing feedback verification before motor activation. This feedback mechanism maintains ease of operation by responding naturally to trigger movement while filtering out noise through redundant verification.

Inventive Principle:

Principle #23Feedback

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 ensures precise control over motor operation, reducing noise interference and maximizing battery life by efficiently switching between cutting speeds and distances, allowing for effective pruning of various branch sizes while minimizing energy consumption.

Implementation Method 1

a trigger potentiometer coupled to the trigger... receive at least one trigger potentiometer voltage signal

Methodology Applied

Scientific EffectPotentiometer voltage signal detection:

Implementation Method 2

a magnet disposed on the trigger, and a trigger hall board adjacent the magnet... receive at least one trigger hall sensor voltage signal

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20240407303A1Pruning shears

Publication Date: 2024.12.12 MILWAUKEE ELECTRIC TOOL CORP

AI summary

Pruning shears including a housing including a motor portion; a handle portion; a motor disposed within the motor portion of the housing; a motor control unit operably coupled to the motor; and a trigger assembly disposed within the handle portion and operably coupled to the motor control unit to control the motor, wherein the trigger assembly includes a trigger; a primary trigger movement detector; and a redundant trigger movement detector, wherein the primary trigger movement detector and the redundant trigger movement detector each sense movement of the trigger when the trigger is pressed and send signals to the motor control unit to control operation of the motor.