Power Tool Nosecone Discharge Path for ESD Protection

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Solution Overview

Problem

High voltage and electrostatic discharge in power tools can cause significant damage to electronic components due to current paths through the nosecone assembly to the battery pack, necessitating a protective mechanism.

Innovation Solution

A discharge wire is coupled between the transmission assembly and the battery pack, providing a direct path to bypass the electronic power module, thereby protecting it from electrostatic discharge and high voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the nosecone assembly is made of metal to protect structural integrity, then strength and durability are improved, but susceptibility to electrostatic discharge and high voltage damage increases

Engineering Contradiction:
Improvestructural integrityVSAvoidelectrostatic discharge damage
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

A discharge wire is introduced as an intermediary component between the metal nosecone assembly and the battery pack. This wire provides a dedicated low-impedance path for electrostatic discharge and high voltage currents, mediating the harmful electrical energy before it can reach and damage the electronic components. The discharge wire acts as a sacrificial conductor that safely channels destructive currents away from sensitive electronics while allowing the metal nosecone to maintain its structural protective function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If a discharge path is provided through electronic components to the battery pack, then electrostatic discharge is dissipated, but electronic components are damaged

Engineering Contradiction:
Improveelectrostatic discharge dissipationVSAvoidelectronic component integrity
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The discharge path is segmented into two distinct routes: a protected path through the electronic components and an unprotected dedicated path via the discharge wire. By segmenting the discharge path, the invention directs harmful electrostatic discharge and high voltage currents exclusively through the discharge wire, which is specifically designed to handle such currents. This segmentation isolates the electronic components from harmful electrical events while maintaining necessary functional connectivity, thereby preserving electronic component integrity during electrostatic discharge events.

Inventive Principle:
Principle #1Segmentation

3Use of energy by moving object

If the transmission assembly is connected to the battery pack through electronic components, then power transmission is achieved, but vulnerability to high voltage damage increases

Engineering Contradiction:
Improvepower transmissionVSAvoidhigh voltage damage
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The discharge wire serves as an intermediary safety mechanism that parallels the normal power transmission path. During normal operation, the electronic components handle power transmission efficiently. During high voltage or electrostatic discharge events, the discharge wire activates as an alternative pathway, providing a low-impedance route to ground that bypasses the electronic components. This dual-path approach allows uninterrupted power transmission functionality while adding protective capability against electrical surges.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively dissipates electrostatic discharge and high voltage without damaging the electronic components, ensuring the power tool's operational integrity.

Implementation Method 1

electrostatic discharge may build up in the power tool components, such as the transmission components

Methodology Applied
Scientific EffectElectrostatic discharge: Electrostatic Discharge

Implementation Method 2

a discharge wire coupled to the power terminal of the terminal block on a first end thereof and to the metal body of the transmission assembly on a second end thereof to provide a discharge path

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4079457B1Transmission assembly to battery connection in power tool
Publication Date: 2026.03.18 BLACK & DECKER CORP
  • EP4079457B1 patent drawingFigure 1
  • EP4079457B1 patent drawingFigure 2A
  • EP4079457B1 patent drawingFigure 2B

AI summary

A power tool is provided an electric motor, a nosecone assembly having a metal body, a terminal block that couples to a removable battery pack, and an electronic power module that regulates supply of electric current from the battery pack to the motor. A discharge wire is coupled to the terminal block on a first end and to the metal body of the nosecone assembly on a second end to provide a discharge path from the nosecone directly to the battery pack bypassing the electronic power module.