Magnetic Drill Press Alternate Power Circuit

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Solution Overview

Problem

Magnetic drill presses face issues with motor inertia causing unintended movement and drill bit breakage when the power supply is unexpectedly interrupted, leading to the electromagnet de-energizing.

Innovation Solution

Incorporating an alternate power supply circuit with a battery and detector that monitors the DC voltage output by an AC/DC converter, providing a backup DC voltage to the electromagnet when the primary power source is absent, ensuring continuous magnetic coupling and stability during drilling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electromagnet is powered only by the primary AC power source, then the device complexity is low, but the reliability deteriorates when power is interrupted

Engineering Contradiction:
Improvemagnetic coupling stabilityVSAvoidpower supply system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The battery is pre-charged and positioned in the circuit as a standby power source before any power interruption occurs. The detector is continuously monitoring the DC voltage from the AC/DC converter, ready to switch to battery power immediately when the primary power fails, ensuring no interruption in electromagnetic coupling.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The detector acts as an intermediary between the AC/DC converter and the battery, monitoring the DC voltage and controlling the switching between power sources. When the detector senses voltage drop below a threshold, it automatically activates the battery circuit, providing seamless power transition without requiring complex control systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the electromagnet is de-energized when AC power is removed, then the energy consumption is reduced, but the harmful effects increase due to drill press movement and drill bit breakage

Engineering Contradiction:
Improvedrill bit breakageVSAvoidelectromagnet energy consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The system converts the harmful effect of sudden power loss (which causes drill press movement and drill bit breakage) into a beneficial outcome by using the battery to maintain electromagnetic coupling during the brief transition period. The detector identifies the power loss condition and activates the battery, transforming what would be a harmful interruption into a controlled, seamless power transition that protects the drill bits and workpiece.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

Prevents drill bit breakage by maintaining magnetic attachment to the work surface even when the primary power source is interrupted, ensuring safe and reliable operation of the magnetic drill press.

Implementation Method 1

a AC/DC converter configured to receive the AC input signal and, independent from the controller and in the presence of the AC input signal, to output the DC voltage to the electromagnet

Methodology Applied
Scientific EffectAC/DC conversion: Electromagnetic Induction

Implementation Method 2

an electromagnet arranged in a base of the drill housing and powered by a DC voltage, to magnetically couple the base to the surface

Methodology Applied
Scientific EffectElectromagnetism: Electromagnet

Implementation Method 3

an alternate power supply circuit that monitors the DC voltage output by the converter and, in the absence of the DC voltage, provides an alternate DC voltage to the electromagnet

Methodology Applied
Scientific EffectBattery: Battery (electricity)

Data Source

PatentEP3109008B1Magnetic drill press with alternate power source
Publication Date: 2018.08.15 BLACK & DECKER CORP
  • EP3109008B1 patent drawingFigure 1
  • EP3109008B1 patent drawingFigure 2
  • EP3109008B1 patent drawingFigure 3

AI summary

A magnetic drill (10) is provided with an alternate power source (36). The drill (10) comprises: an electric motor (32) for driving a tool; a controller (33) configured to receive an AC input signal and operable to control a drive signal to the electric motor (32); an electromagnet (28) arranged in a base (24) of the drill housing and operable, in response to a DC voltage, to magnetically couple the base to a surface proximate to the base (24); an AC/DC converter (34) configured to receive the AC input signal and operates, independent from the controller (33) and in the presence of the AC input signal, to output a DC voltage to the electromagnet (28); and an alternate power source circuit that monitors the DC voltage output by the converter (34) and, in the absence thereof, provides an alternate DC voltage to the electromagnet (28).