Angularly Movable Bearing Sleeve for Steering Pinion

Solution Overview

Problem

Helical gear mechanisms in power steering systems face challenges in minimizing tooth flank clearance while allowing radial movement of the pinion, leading to increased friction, noise, and reduced service life due to tilting of the bearing arrangement, especially with reduced axial clearance.

Innovation Solution

A helical gear mechanism with a bearing arrangement featuring a sleeve with a convex or crowned inner contact surface and a cylindrical outer contact surface, forming an angularly movable joint with the housing, which allows for pivoting of the helical pinion without tilting the motor, and includes axial spring elements for tilting compensation, using elastomer preload elements and expansion slots for radial expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the axial clearance of the bearing is minimized to reduce steering knocking and rattling noises, then the bearing becomes more sensitive to tilting, leading to increased friction, severe fluctuations in friction, noises and reduced service life

Engineering Contradiction:

Improvesteering knocking and rattling noisesVSAvoidservice life of bearing arrangement

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The bearing arrangement is designed to be dynamically tiltable about a pivot axis perpendicular to the longitudinal axis of the pinion. The sleeve with its convex inner contact surface and cylindrical outer contact surface forms an angularly movable joint that allows controlled tilting movement while maintaining bearing preload, thus accommodating pinion radial movement without causing harmful tilting effects

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The bearing clearance parameters are optimized by using four-point bearings or similar bearings with minimized axial clearance. The sleeve geometry (convex inner surface, cylindrical outer surface) is specifically designed to maintain optimal clearance parameters during tilting movement, reducing friction fluctuations while maintaining low noise operation

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the pinion axis is pivoted out of its central position to eliminate tooth flank clearance, then the bearing arrangement tilts, causing increased friction and reduced service life

Engineering Contradiction:

Improvetooth flank clearanceVSAvoidservice life of bearing arrangement

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The bearing arrangement is designed to be dynamically tiltable about a pivot axis perpendicular to the longitudinal axis of the pinion. The sleeve with its convex inner contact surface and cylindrical outer contact surface forms an angularly movable joint that allows controlled tilting movement while maintaining bearing preload, thus accommodating pinion radial movement without causing harmful tilting effects

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The sleeve acts as an intermediary element between the bearing outer ring and the housing. It provides a geometric interface (convex inner surface contacting cylindrical outer surface) that enables the bearing to tilt relative to the housing while maintaining proper alignment and preload, thus mediating between the pinion's radial movement requirement and the bearing's alignment requirement

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If four-point bearings with minimized axial clearance are used to reduce noise, then the bearing arrangement becomes even more sensitive to tilting

Engineering Contradiction:

Improvesteering knocking and rattling noisesVSAvoidsensitivity to tilting

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The bearing arrangement is designed to be dynamically tiltable about a pivot axis perpendicular to the longitudinal axis of the pinion. The sleeve with its convex inner contact surface and cylindrical outer contact surface forms an angularly movable joint that allows controlled tilting movement while maintaining bearing preload, thus accommodating pinion radial movement without causing harmful tilting effects

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The bearing clearance parameters are optimized by using four-point bearings or similar bearings with minimized axial clearance. The sleeve geometry (convex inner surface, cylindrical outer surface) is specifically designed to maintain optimal clearance parameters during tilting movement, reducing friction fluctuations while maintaining low noise operation

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 configuration maintains constant tooth clearance over the gear mechanism's service life, reduces tilting moments, and minimizes friction and noise, enabling the use of bearings with minimized axial clearance, such as four-point bearings, while extending the service life and improving steering feel.

Implementation Method 1

the bearing arrangement is received in a housing, wherein, between the bearing outer ring and the housing, there is arranged a sleeve... includes axial spring elements for tilting compensation

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

using elastomer preload elements and expansion slots for radial expansion

Methodology Applied

Scientific EffectElastic recovery: Elasticity

Data Source

PatentUS9988071B2Angularly movable bearing arrangement for pinions in reduction gears of electromechanical steering systems

Publication Date: 2018.06.05 THYSSENKRUPP PRESTA AG

AI summary

A bearing arrangement for a motor vehicle steering system includes a sleeve arranged between an outer bearing ring and a housing. The sleeve includes an inner contact surface in contact with an outer circumferential surface of the outer bearing ring, and an outer contact surface in contact with a seat surface of the housing, wherein either of the inner contact surface or the outer contact surface of the sleeve are convex shaped.