Motor Baffle Design for Axial Length Reduction and Cooling

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Solution Overview

Problem

Existing electric tools face challenges in minimizing axial length while maintaining effective cooling, as the baffle's positioning and thickness are compromised during assembly, leading to potential degradation in cooling efficiency and increased tool length.

Innovation Solution

A separate baffle is positioned within the motor housing, with at least part of its width within the axial length of the stator, allowing for reduced axial length without compromising cooling efficiency, and is engaged with retainers to prevent rotation and additional mounting mechanisms, forming a labyrinth seal to prevent air leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the baffle is positioned closer to the motor to reduce axial length, then the axial length of the electric tool is reduced, but the mounting space for the motor assembly is insufficient

Engineering Contradiction:
Improveaxial length of electric toolVSAvoidmounting operation of motor assembly
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

The baffle is divided into a first baffle portion and a second baffle portion positioned at different axial locations. The first portion is closer to the motor for effective cooling flow regulation, while the second portion extends axially to provide mounting space for the motor assembly, allowing both functions to coexist without interference

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The baffle extends in the radial direction from the inner circumferential wall of the motor housing, utilizing the radial dimension to provide both the cooling flow regulation function (by positioning the leading edge close to the motor) and the mounting support function (by extending radially outward to provide clearance space)

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If the baffle thickness is increased to ensure proper molding and structural integrity, then the baffle can be properly manufactured, but the axial length of the electric tool increases

Engineering Contradiction:
Improvemolding of baffleVSAvoidaxial length of electric tool
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The baffle has different thickness characteristics at different locations: the portion extending radially from the motor housing has sufficient thickness for proper molding and structural integrity, while the axial projection portion has reduced thickness, allowing the baffle to be properly manufactured without increasing the overall axial length of the electric tool

Inventive Principle:
Principle #3Local quality

3Reliability

If the baffle is positioned to restrict cooling air flow area, then cooling efficiency of the stator coil is improved, but the mounting space for the motor assembly is reduced

Engineering Contradiction:
Improvecooling efficiency of stator coilVSAvoidmounting space in motor housing
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The baffle is segmented into portions that perform different functions: the first portion restricts the cooling air flow area to improve cooling efficiency of the stator coil, while the second portion provides mounting space for the motor assembly, allowing both cooling efficiency and mounting space requirements to be satisfied simultaneously

Inventive Principle:
Principle #1Segmentation

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

This configuration reduces the axial length of the electric tool while maintaining effective cooling and preventing air leakage, enhancing the tool's overall efficiency and assembly ease.

Implementation Method 1

A baffle (106) may be disposed within the motor housing for regulating the flow of cooling air across the motor

Methodology Applied
Scientific EffectFluid flow regulation:

Implementation Method 2

Cooling air can flow within the motor housing across the motor in a direction substantially parallel to the motor axis

Methodology Applied
Scientific EffectForced convection cooling: Forced Convection

Data Source

PatentEP2561963B1Electric tools
Publication Date: 2020.05.27 MAKITA CORP
  • EP2561963B1 patent drawingFigure 1
  • EP2561963B1 patent drawingFigure 2
  • EP2561963B1 patent drawingFigure 3

AI summary

An electric tool (1) may include a motor housing (11) and a motor (2) disposed within the motor housing (11). The motor (2) has a stator (21) fixed in position relative to the motor housing (11) and a rotor (28) rotatable about a motor axis. Cooling air can flow within the motor housing (11) across the motor (2) in a direction substantially parallel to the motor axis. A baffle (5; 105) may be disposed within the motor housing (11) for regulating the flow of cooling air across the motor (2). At least a part of the baffle (5; 105) may be positioned within a range of a length of the stator (21) with respect to the axial direction of the motor axis.