EPS Housing Vent Filter Layout for Waterproof Pressure Equalization

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Solution Overview

Problem

Conventional electric power steering apparatuses with integrated motors and control units face challenges in maintaining waterproofing, particularly when exposed to water and dust, due to inadequate sealing around the output axle and respiratory actions that compromise the waterproofing members, leading to potential water intrusion.

Innovation Solution

The electric power steering apparatus incorporates a motor housing with one sealed end and one open end, coupled with a control unit housing having the opposite configuration, featuring respiratory apparatuses with filters to manage pressure changes and prevent water ingress, ensuring both motor and control unit waterproofing and respiratory functions are maintained.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a seal or O-ring is applied to the coupling portion between the motor and control unit for waterproofing, then waterproofing performance is improved, but the respiratory function is compromised and pressure changes cause deterioration of the waterproofing member

Engineering Contradiction:
Improvewaterproofing performanceVSAvoidrespiratory function
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent divides the sealing system into two functional segments: a waterproofing member (seal/O-ring) for preventing water intrusion and a respiratory member (filter) for managing pressure changes. This segmentation allows each component to perform its specific function without compromising the other, resolving the contradiction between waterproofing and respiratory needs

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a respiratory member (filter) as an intermediary component that mediates between the need for waterproofing and the need for pressure equalization. The filter allows air to pass through while blocking water, enabling the system to maintain both waterproofing integrity and respiratory function simultaneously

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a filter is inserted into a respiratory hole to prevent water intrusion, then waterproofing is improved, but the respiratory function may be restricted

Engineering Contradiction:
ImprovewaterproofingVSAvoidrespiratory function efficiency
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a porous filter material with carefully controlled pore sizes that are large enough to allow air flow for respiratory function but small enough to block water intrusion. The porous structure provides both filtering capability and adequate air permeability

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent optimizes the filter's physical parameters (pore size, porosity, thickness) to achieve the right balance between water blocking and air flow. By adjusting these parameters, the system maintains effective respiratory function while ensuring waterproofing performance

Inventive Principle:
Principle #35Parameter changes

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 design effectively secures the waterproof performance and respiratory function of the electric power steering apparatus, even under conditions of temperature changes and potential water submersion, by using filters in respiratory apparatuses to prevent water intrusion and maintain the integrity of the waterproofing measures.

Implementation Method 1

a filter is inserted into the respiratory hole... the air inlet reduces or relaxes the pressure difference between the inside and the outside of the electric power steering apparatus so that water is prevented from intruding

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP3798093B1Electric power steering apparatus
Publication Date: 2023.11.29 MITSUBISHI ELECTRIC CORP
  • EP3798093B1 patent drawingFigure 1
  • EP3798093B1 patent drawingFigure 2
  • EP3798093B1 patent drawingFigure 3A

AI summary

There is provided an electric power steering apparatus in which at least one of a motor housing and a control unit has a respiratory apparatus that performs a respiratory action, based on an inner pressure change in at least one of the motor housing and the control unit.