Brushless DC Motor End Cap Heat Dissipation

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Solution Overview

Problem

Brushless motors in power tools face challenges in heat dissipation due to obstructed airflow, particularly when the controller and MOSFETs are located in the handle, leading to reduced cooling efficiency and a less compact design.

Innovation Solution

An end cap with fins serves as a heat sink, directly or thermally coupled to the controller and MOSFETs, effectively dissipating heat through the end cap, providing a compact design for improved cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the controller and MOSFETs are placed in the handle of the tool, then the design becomes less compact and cooling becomes more difficult, but this placement is chosen due to space limitations in the motor housing

Engineering Contradiction:

Improvemotor housing spaceVSAvoidheat dissipation efficiency

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The controller and MOSFETs are extracted from the motor housing and placed in the handle of the tool. This resolves the space constraint in the motor housing while the end cap provides an alternative heat dissipation path that compensates for the reduced airflow cooling in the handle location.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The end cap acts as an intermediary heat dissipation component. It is thermally coupled to the controller and MOSFETs in the handle, providing a dedicated heat sink function that compensates for the obstructed airflow conditions at the handle location.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If airflow from the motor fan is used for cooling, then cooling effectiveness is reduced when components are placed in the handle, but this is the typical cooling method for power tools

Engineering Contradiction:

Improvecooling effectivenessVSAvoidairflow obstruction

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The end cap serves as an intermediary heat dissipation structure that is thermally coupled to the controller and MOSFETs. It provides an alternative heat transfer path that does not rely on the obstructed airflow from the motor fan, thereby maintaining cooling effectiveness despite airflow limitations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces reliance on mechanical airflow cooling (which is obstructed when components are in the handle) with a thermal conduction-based heat sink system. The end cap conducts heat away from the components through direct thermal contact, substituting the airflow cooling mechanism with a conduction-based approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 end cap enhances heat dissipation, maintaining the motor's performance while offering a more compact and structurally stable design by efficiently dissipating heat from the heat-generating components.

Implementation Method 1

The switching elements are thermally coupled to the end cap

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The end cap includes fins to dissipate heat

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS11658545B2Brushless direct current motor end cap

Publication Date: 2023.05.23 SNAP ON INC

AI summary

An end cap for a brushless motor that dissipates heat from a controller and switching elements of the motor through fins in the end cap. The end cap can be directly or thermally coupled to the controller and switching elements to dissipate heat out through the fins.