Chop Saw Motor Control Using Position-Based Blade Speed

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Solution Overview

Problem

Chop saws face limitations in maximizing the number of cuts without requiring battery pack disconnection for recharging, as existing motor control systems do not efficiently manage blade speed and energy usage across different cutting positions and angles.

Innovation Solution

A motor control system that utilizes position sensors to adjust blade speed based on the saw assembly's position relative to the table and base, incorporating features like potentiometers, switches, rotary encoders, and range finders to optimize blade speed and engage regenerative charging, thereby extending battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the motor runs at high speed to maximize cutting performance, then the cutting efficiency is improved, but the battery is depleted faster requiring frequent recharging

Engineering Contradiction:
Improvecutting efficiencyVSAvoidbattery run time
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The motor controller dynamically adjusts the motor speed based on real-time feedback from position sensors. When the saw assembly is in non-cutting positions (above the workpiece), the motor operates at reduced speed or idle state. When the blade contacts the workpiece, the motor automatically increases to high speed for efficient cutting. This dynamic speed adjustment maintains high productivity during actual cutting while minimizing energy consumption during positioning, thereby extending battery run time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates position sensors that continuously monitor the location of the saw assembly relative to the workpiece and provide feedback to the motor controller. This feedback mechanism enables the controller to intelligently adjust motor speed based on whether the blade is in contact with the workpiece or in transit positions, optimizing the balance between cutting efficiency and energy consumption to maximize battery run time.

Inventive Principle:
Principle #23Feedback

2Duration of action of moving object

If the motor speed is reduced to conserve battery power, then the battery run time is extended, but the cutting performance and efficiency deteriorate

Engineering Contradiction:
Improvebattery run timeVSAvoidcutting efficiency
Core Design Contradiction:
Duration of action of moving objectVSProductivity

Solution Approach 1:

The motor controller dynamically adjusts the motor speed based on real-time feedback from position sensors. When the saw assembly is in non-cutting positions (above the workpiece), the motor operates at reduced speed or idle state. When the blade contacts the workpiece, the motor automatically increases to high speed for efficient cutting. This dynamic speed adjustment maintains high productivity during actual cutting while minimizing energy consumption during positioning, thereby extending battery run time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates position sensors that continuously monitor the location of the saw assembly relative to the workpiece and provide feedback to the motor controller. This feedback mechanism enables the controller to intelligently adjust motor speed based on whether the blade is in contact with the workpiece or in transit positions, optimizing the balance between cutting efficiency and energy consumption to maximize battery run time.

Inventive Principle:
Principle #23Feedback

3Productivity

If the blade speed is increased to make faster cuts, then the productivity is improved, but the energy consumption increases requiring more frequent battery recharging

Engineering Contradiction:
Improvecutting speedVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The motor controller dynamically adjusts the motor speed based on real-time feedback from position sensors. When the saw assembly is in non-cutting positions (above the workpiece), the motor operates at reduced speed or idle state. When the blade contacts the workpiece, the motor automatically increases to high speed for efficient cutting. This dynamic speed adjustment maintains high productivity during actual cutting while minimizing energy consumption during positioning, thereby extending battery run time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates position sensors that continuously monitor the location of the saw assembly relative to the workpiece and provide feedback to the motor controller. This feedback mechanism enables the controller to intelligently adjust motor speed based on whether the blade is in contact with the workpiece or in transit positions, optimizing the balance between cutting efficiency and energy consumption to maximize battery run time.

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

The system effectively maximizes the number of cuts by optimizing blade speed and energy usage, reducing waste and extending battery run time by intelligently managing motor speed and initiating regenerative charging.

Implementation Method 1

a motor (45) supported by arm (41) and/or upper blade guard (42), a blade (43) driven by the motor (45)

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

incorporating features like potentiometers, switches, rotary encoders, and range finders to optimize blade speed

Methodology Applied
Scientific EffectPotentiometer resistance change: Piezoresistive Effect

Data Source

PatentEP3368239B1Chop saw with improved motor controls
Publication Date: 2021.07.28 BLACK & DECKER CORP
  • EP3368239B1 patent drawingFigure 1~2
  • EP3368239B1 patent drawingFigure 3~6
  • EP3368239B1 patent drawingFigure 7~9

AI summary

A chop saw has a base assembly, a support housing connected to the base assembly, a saw assembly pivotally connected to the support housing allowing the saw assembly to be pivoted downwardly towards the base assembly for conducting a cutting operation on a workpiece. The saw assembly has a motor, a blade driven by the motor and an upper blade guard for covering an upper portion of the blade. A sensor assembly senses a position of the saw assembly relative to the workpiece and/or the support housing. A controller receives a signal an input representative of the position of the saw assembly from the sensor assembly and controls the motor according to such signal.