Electric Fan Water Infiltration Prevention via Labyrinth Sealing

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Solution Overview

Problem

Conventional electric fans used to cool automobile radiators face issues with water infiltration due to the rotor yoke's rotation relative to the motor holder, creating a simple intrusion path that is difficult to effectively suppress.

Innovation Solution

The design incorporates a fan boss and fan shroud that cover the electric motor, with labyrinth portions between the fan boss and shroud, and between the shroud and bracket, to complicate the water intrusion path and prevent infiltration, while also providing a gap for water discharge and enhanced cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotor yoke rotates on the outer side of the stator, then the electric motor can generate cooling air, but water easily enters from the outside due to the open type configuration

Engineering Contradiction:

Improvecooling air generationVSAvoidwater infiltration

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The fan boss is divided into multiple segments in the axial direction, creating multiple water discharge paths. This segmentation allows water to be discharged efficiently while maintaining the rotational function of the rotor yoke for cooling air generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fan boss acts as an intermediary component between the rotor yoke and the external environment. It provides a protected pathway for water discharge while allowing the rotor yoke to rotate freely for generating cooling air, thus mediating between the conflicting requirements of cooling efficiency and water protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a separate cover is provided to ensure water-tightness, then water infiltration is prevented, but the size of the electric motor increases

Engineering Contradiction:

Improvewater infiltration preventionVSAvoidelectric motor size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The fan boss serves multiple functions: it maintains the structural integrity of the fan assembly, allows rotational movement of the rotor yoke, provides water discharge paths, and protects internal components from water infiltration. This multi-functionality eliminates the need for a separate cover, preventing water infiltration without increasing motor size.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If a gap is formed between the motor holder and the opening of the rotor yoke, then the rotor yoke can rotate, but water intrudes from this gap into the interior

Engineering Contradiction:

Improverotor yoke rotationVSAvoidwater intrusion

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The solution moves from a two-dimensional gap problem to a three-dimensional water discharge pathway. The fan boss creates axial water discharge paths that extend in the third dimension (axial direction), allowing water to be actively discharged from the gap area rather than simply blocking the gap, thus maintaining rotor rotation while preventing water accumulation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively suppresses water infiltration into the electric motor, prevents heat damage, and maintains lubrication performance by preventing water from reaching the bearings, thus improving durability and sound resistance.

Implementation Method 1

When electric current is supplied to the coil, an electrical field is formed around the stator teeth. As a result, electromagnetic attraction and repulsion which cause the rotor yoke to rotate are generated between the stator teeth and the permanent magnet of the rotor yoke

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

electromagnetic attraction and repulsion which cause the rotor yoke to rotate are generated between the stator teeth and the permanent magnet of the rotor yoke and cooling air is generated in an axial direction of the rotating shaft by the fan blades

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS9249788B2Electric fan

Publication Date: 2016.02.02 MITSUBA CORP

AI summary

This electric fan has a rotation shaft that is provided rotatably with respect to a stator, a rotor yoke provided on the rotation shaft and formed in a bottomed cylindrical shape so as to cover the stator from a front surface, and a bracket that fixes the stator to a fan shroud and is formed so as to cover a rear surface of the stator, with a fan body provided so as to integrally rotate with the rotation shaft and the rotor yoke. The fan body has a fan boss formed in a bottomed cylindrical shape so as to cover the rotor yoke from a front surface, and a plurality of blades that is provided protruding radially from an outer circumferential surface of the fan boss. A first labyrinth portion is provided between an opening portion of the fan boss and the fan shroud.