Steering Gear Housing Integration for Accurate EPS Alignment

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Solution Overview

Problem

Existing electric power steering systems face challenges in achieving improved operational accuracy and reliability by precisely determining the relative positions of the input mechanism, speed reducer, and drive device components.

Innovation Solution

A steering device design that integrates a first gear mechanism for converting and outputting rotation, a second gear mechanism for decelerating rotation, and a drive device with a controller, where the flange and case are integrally formed, and washer plates are used to secure the gear case, reducing surface pressure and deformation, and the controller has a flat shape to reduce thickness while maintaining reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of stationary object

If the flange and case are integrally formed, then the number of parts and weight are reduced, but the manufacturing complexity increases

Engineering Contradiction:
ImproveweightVSAvoidmanufacturing complexity
Core Design Contradiction:
Weight of stationary objectVSEase of manufacture

Solution Approach 1:

The flange and case are integrally formed as a single component, merging two previously separate parts into one. This reduces the total number of parts and the overall weight of the steering device, while the integral formation ensures precise relative positioning between the first and second gear mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If multiple separate washers are provided for each fastener, then the fastening is simplified, but the surface pressure on the flange increases causing deformation

Engineering Contradiction:
Improvefastening simplicityVSAvoidsurface pressure
Core Design Contradiction:
Ease of manufactureVSStress or pressure

Solution Approach 1:

A single washer plate is introduced as an intermediary component between the fasteners and the flange. This washer plate distributes the clamping force from multiple fasteners over a larger surface area of the flange, reducing surface pressure and preventing deformation, while still maintaining simple fastening procedures.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the controller is positioned at the end of the drive device, then the axial length increases, but the reliability is improved

Engineering Contradiction:
ImprovereliabilityVSAvoidaxial length
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The controller is positioned at the end of the drive device in the axial direction, utilizing the axial dimension for placement. This positioning improves reliability by securing the controller in a stable location, while the integral flange-case structure provides a compact overall configuration that minimizes the impact on total axial length.

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

Data Source

PatentEP4707126A1Steering device
Publication Date: 2026.03.11 NABTESCO CORP
  • EP4707126A1 patent drawingFigure 1A~1B
  • EP4707126A1 patent drawingFigure 2
  • EP4707126A1 patent drawingFigure 3

AI summary

A steering device (10) according to one aspect of the invention includes: a first gear mechanism (11) configured to receive rotation of steering wheel operation, convert a direction of the rotation, and output converted rotation as primary rotation; and a second gear mechanism (20) configured to receive the primary rotation output from the first gear mechanism (11), decelerate the primary rotation, and output decelerated rotation. The first gear mechanism (11) includes: conversion mechanism parts (11d) for converting the direction of the rotation; and a case (12) housing the conversion mechanism parts (11d). The second gear mechanism (20) includes: reduction mechanism parts (20d) for decelerating the primary rotation; an output shaft (25) for outputting the decelerated rotation; and a gear case (21) housing the reduction mechanism parts (20d). A flange (37) is provided on the gear case (21), the flange (37) forming a side of the gear case (21) facing an axial direction of the output shaft (25). The flange (37) and the case (12) are integrally formed with each other.