Wave Spring with Insulating Layer for Power Steering

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Solution Overview

Problem

Existing power steering systems with electromotive servo drives face challenges in accommodating axial and tilting movements of the ball nut due to their design, which often results in complex component production and assembly, and inadequate damping with high installation height.

Innovation Solution

A power steering system utilizing corrugated spring assemblies with elastic intermediate layers for axial and radial support, allowing for axial deflection and tilting of the ball nut, while providing impact damping through energy consumption and a compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If spherical bearings or barrel roller bearings are used to allow axial and tilting movements of the ball nut, then the bearing can accommodate dynamic loads and thermal expansion, but the bearing is designed more for radial forces rather than axial loads

Engineering Contradiction:
Improveability to accommodate axial and tilting movementsVSAvoidaxial load capacity
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The bearing assembly is segmented into multiple functional components: spring elements for axial support, damping elements for radial support and pivoting, and a spherical interface for tilt accommodation. This segmentation allows each element to specialize in handling specific force components, resolving the contradiction between axial load capacity and movement adaptability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bearing assembly uses composite structural design combining metallic spring elements, polymeric damping elements, and spherical surfaces. This composite approach enables the system to simultaneously handle axial loads (via springs), radial loads (via damping elements), and tilting movements (via spherical interface), overcoming the limitation of conventional bearings designed for单一 force type.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If conventional damping elements are used to dampen dynamic loads, then the damping effect is achieved, but the installation height becomes large

Engineering Contradiction:
Improvedamping of dynamic loadsVSAvoidinstallation height
Core Design Contradiction:
Loss of energyVSLength of moving object

Solution Approach 1:

The damping function is extended from purely axial damping to include radial damping through the spherical interface between the outer bearing ring and frame. This multi-dimensional damping approach allows the system to achieve comprehensive dynamic load dampening without increasing axial installation height, as radial damping acts perpendicular to the axial direction.

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

Solution Approach 2:

The spherical interface serves multiple functions simultaneously: it enables tilting movements, provides radial damping, and accommodates misalignment. This multi-functionality eliminates the need for separate damping components that would increase installation height, as the same spherical interface performs both movement accommodation and damping functions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If complex component designs are used to enable axial and tilting movements, then the bearing functionality is improved, but the production and assembly become complex

Engineering Contradiction:
Improvepivotability of the bearingVSAvoidcomponent production and assembly complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The complex bearing functionality is segmented into standardized, pre-manufactured components: a bearing assembly with spring elements, damping elements, and spherical interfaces. This segmentation allows each component to be manufactured independently using standard processes, then assembled together to achieve the complex overall functionality, thereby reducing both production and assembly complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spherical interface acts as an intermediary element that simplifies the connection between the bearing assembly and the frame. This spherical interface naturally accommodates tilting movements and misalignment without requiring complex adjustment mechanisms, thereby simplifying both the design and assembly processes while maintaining high adaptability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

The solution enables simplified assembly, effective damping of dynamic loads, and reduced mechanical play, achieving improved acoustic properties and ease of installation with a low profile.

Implementation Method 1

the spring elements being designed as corrugated spring assemblies, the corrugated spring assemblies each having at least two elements, of which at least one element is a corrugated spring

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

effective damping of dynamic loads, and reduced mechanical play, achieving improved acoustic properties

Methodology Applied
Scientific EffectDamping: Damping

Implementation Method 3

at the end of the deformation path of the corrugated spring, impact damping is achieved, since the metallic corrugated spring cannot strike directly against the frame or the associated thrust washer, but against the intermediate layer

Methodology Applied
Scientific EffectImpact damping: Damping

Data Source

PatentEP2986485B1Double wave spring with insulating intermediate layer
Publication Date: 2017.09.13 THYSSENKRUPP PRESTA AG
  • EP2986485B1 patent drawingFigure 1~2
  • EP2986485B1 patent drawingFigure 3~6
  • EP2986485B1 patent drawingFigure 7~12

AI summary

The invention relates to a power steering system, in particular for a motor vehicle, comprising a servomotor which drives an axially movable component via a nut (1) mounted in a bearing (4) in a rotatable manner in a frame (9, 10). The nut (1) is engaged with a threaded spindle (2) formed on the component and is supported axially by the bearing (4) in an elastic manner relative to the frame (9, 10) by means of elastic elements (18, 20) and radially on the frame (9, 10) along a narrow circumferential contact surface (8, 30). Each wave spring assembly (18, 20) has at least two elements, at least one element of which is a wave spring (128, 130), and an elastic intermediate layer (118, 120) is arranged between each of the at least two elements.