Brushless Power Tool Circuit Layout for Compact Heat Control

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Solution Overview

Problem

Existing handheld power tools with brushless electric motors suffer from increased volume due to multiple circuit boards, generate undesirable heat, and are less reliable due to susceptible connections between these boards.

Innovation Solution

A handheld grinder with a brushless electric motor that integrates a rectifier, capacitor, and power switch onto a single circuit board, using compact DC bus capacitors and a heat sink to minimize heat generation and inter-board connections, enhancing reliability and reducing size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple circuit boards are used to support the capacitor, power switch and control circuitry, then the power tool can perform required functions, but the volume of the power tool increases

Engineering Contradiction:

Improvefunctional capabilityVSAvoidpower tool volume

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent combines the capacitor, power switch, and control circuitry onto a single circuit board, eliminating the need for multiple separate circuit boards. This integration reduces the overall volume occupied by electrical components while maintaining all necessary functions for operating the brushless electric motor.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single circuit board serves multiple functions simultaneously: it supports the capacitor for energy storage, houses the power switch for current control, and provides the control circuitry for motor operation. This multi-functional design eliminates the need for separate dedicated boards for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If the capacitor and power switch are used to control current flow and reduce ripple, then the brushless electric motor operates reliably, but undesirable heat is generated

Engineering Contradiction:

Improvemotor operation reliabilityVSAvoidheat generation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent acknowledges that heat generation from the capacitor and power switch is inevitable but converts this harmful effect into a manageable design consideration by providing adequate ventilation and heat dissipation pathways within the housing, thereby maintaining reliability while managing the thermal byproduct.

Inventive Principle:

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

Solution Approach 2:

The circuit board acts as an intermediary platform that organizes and manages the thermal characteristics of the capacitor and power switch, allowing for optimized thermal design through proper component placement and heat dissipation structures integrated into the board design.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If multiple circuit boards are used to support electrical components, then the power tool can be assembled with modular components, but the connections between circuit boards are susceptible to wearing out or breaking

Engineering Contradiction:

Improvemodular assemblyVSAvoidconnection durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent consolidates all electrical components (capacitor, power switch, control circuitry) onto a single circuit board, eliminating the need for inter-board connections. This integration removes the reliability issue of connections wearing out or breaking while maintaining ease of manufacture through streamlined assembly of fewer components.

Inventive Principle:

Principle #5Merging (Combining)

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 results in a more compact, reliable, and less heat-generating power tool by minimizing inter-board connections and utilizing compact capacitors and efficient heat dissipation, improving overall performance and durability.

Implementation Method 1

a rectifier configured to receive power from an alternating current (AC) power source and operable to convert an alternating current to a direct current

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 2

a capacitor connected electrically between the rectifier and the switching arrangement, wherein the capacitor is coupled in parallel across the rectifier

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

utilizing compact capacitors and efficient heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12381448B2Handheld power tool with a brushless electric motor

Publication Date: 2025.08.05 BLACK & DECKER CORP

AI summary

A power tool comprising a housing and a brushless direct-current (BLDC) motor disposed within the housing. The motor includes a stator and a rotor rotatable relative to the stator. The power tool is configured to generate a power output from the motor that is greater than 1200 continuous hot Watts out such that a quotient obtained by the power output measured in Watts (Wout), divided by an input measured in Volt-Amperes (Vain), and further divided by a volume of the power tool measured in cubic centimeters (cc), is greater than 600 Wout/Vain/cc.