Steering Rack Housing Cross-Sectional Contractions

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Solution Overview

Problem

The production of rack housings for power steering systems is costly and labor-intensive due to the need for extensive machining and constrictions to secure the support ring, which increases manufacturing effort and costs without reducing the overall diameter of the toothed rack housing.

Innovation Solution

The method involves creating two or more cross-sectional constrictions diametrically opposite on the outer circumference of the rack housing to securely fasten the support ring through a positive fit, eliminating the need for a continuous constriction and simplifying the attachment process, which can be achieved through stamping or other external modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a continuous constriction is produced to secure the support ring, then the support ring is firmly fastened, but the manufacturing effort and costs increase significantly

Engineering Contradiction:
Improvesupport ring fasteningVSAvoidmanufacturing effort
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The continuous constriction is divided into discrete stampings distributed around the circumference. Instead of creating one long continuous constriction, the patent applies multiple separate stampings (typically 2-4) around the rack housing perimeter, each creating a localized constriction that collectively secures the support ring effectively while requiring less manufacturing effort.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The constriction force is applied locally at specific points around the circumference rather than uniformly along the entire circumference. The stampings create localized constrictions at strategically positioned points, which is sufficient to secure the support ring while avoiding the excessive manufacturing effort of a continuous constriction.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If extensive machining is performed on the rack housing, then mounting surfaces and attachment features are created, but production costs and manufacturing time increase

Engineering Contradiction:
Improvemounting surface qualityVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The rack housing is designed to utilize its own structural features for mounting and attachment purposes. The housing geometry itself provides the necessary mounting surfaces and attachment features, eliminating or reducing the need for separate machining operations to create these features, thereby maintaining precision while improving productivity.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If the rack housing diameter is reduced to lower costs, then manufacturing expenses decrease, but the support ring cannot be properly secured

Engineering Contradiction:
Improveproduction costVSAvoidsupport ring attachment
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The support ring securing mechanism is segmented into discrete stampings rather than requiring a continuous constriction. This allows the rack housing to maintain its overall diameter for proper support ring accommodation while using localized stampings to achieve the necessary securing function, thus avoiding the need to reduce the housing diameter.

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 approach reduces production costs and effort by allowing for quicker assembly of the support ring without compromising the quality and performance of the rack housing, enabling precise positioning and cost savings while maintaining high performance standards.

Implementation Method 1

the cross section of the rack housing is changed from the outside with a suitable tool. In a particularly advantageous method, it is sufficient, for example, to make only two stampings from the outside.

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP2411257B1Steering rack housing comprising cross-sectional contractions
Publication Date: 2013.12.04 FORD GLOBAL TECH LLC
  • EP2411257B1 patent drawingFigure 1
  • EP2411257B1 patent drawingFigure 2
  • EP2411257B1 patent drawingFigure 3

AI summary

The invention relates to a steering rack housing (20, 100, 100', 100") for a power steering system, said housing surrounding a steering rack in a tubular manner and comprising at least one hydraulic region (32), a mechanical region (34), and an inner supporting bearing (38). The supporting bearing is held in the housing by at least two cross-sectional contractions (46) of the steering rack housing (20, 100, 100', 100").