Steering Actuator Position Sensing with Compliant Rolling Contact

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Solution Overview

Problem

Existing steering systems face challenges in production complexity and operational reliability due to contamination and transverse forces affecting the rotation sensor, leading to measurement inaccuracies and potential failure.

Innovation Solution

A compliant rotation sensor arrangement is used, where the sensor is mounted transversely to the actuator rod and equipped with a flexible bearing system, allowing it to deflect laterally under transverse forces, thereby reducing material stress and friction, and incorporating an elastic preload to ensure precise and robust position measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the rotation sensor is rigidly mounted to the actuator rod, then the measurement precision is maintained, but the sensor is impaired by transverse forces occurring during operation

Engineering Contradiction:
Improveposition measurement accuracyVSAvoidsensor function reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The rotation sensor is mounted on a bearing that allows it to move dynamically in the transverse direction, enabling the sensor to adapt to transverse forces while maintaining measurement precision through the compliant mounting arrangement

Inventive Principle:
Principle #15Dynamics

2Reliability

If the rotation sensor is made flexible to accommodate transverse forces, then the operational reliability is improved, but the measurement precision may be compromised

Engineering Contradiction:
Improvesensor operation reliabilityVSAvoidposition measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

A bearing is introduced as an intermediary element between the rotation sensor and the actuator rod, allowing the sensor to move compliantly under transverse forces while the bearing maintains the functional relationship and measurement accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If a compliant mounting arrangement is used for the rotation sensor, then the production complexity is reduced and operational reliability is improved, but additional components are required

Engineering Contradiction:
Improveproduction simplicityVSAvoidmounting structure complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

A simple bearing is used as a cost-effective and easy-to-manufacture compliant mounting solution, replacing complex rigid mounting structures while maintaining reliability and measurement precision

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 enhances production simplicity and operational reliability by protecting the sensor from external interference and absorbing transverse forces, ensuring high measurement accuracy and smooth operation.

Implementation Method 1

a running wheel which is mounted on the sensor shaft in a rotationally fixed manner and can roll on a corresponding linear track of the actuator rod in order to convert a translational movement of the actuator rod into a rotation of the sensor shaft

Methodology Applied
Scientific EffectRolling: Roller

Implementation Method 2

The rotation sensor is arranged or designed to be flexible transversely to the track... incorporating an elastic preload to ensure precise and robust position measurement

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4095017B1Steering actuator for a steering system and steering system for a motor vehicle
Publication Date: 2025.07.02 THYSSENKRUPP PRESTA AG
  • EP4095017B1 patent drawingFigure 1~2
  • EP4095017B1 patent drawingFigure 3~4
  • EP4095017B1 patent drawingFigure 5~6

AI summary

The present invention relates to a steering actuator (4) for a steering system (1) for a motor vehicle, comprising an actuator rod (42) that is translationally displaceable in its longitudinal direction and a position sensor device (6) designed to detect the linear position of the actuator rod (42). To enable less complex manufacturing and higher operational reliability, the invention proposes that the position sensor device (6) comprise a rotation sensor (61) having a sensor shaft (62) rotatable about an axis (S) with a wheel (64) which can roll on a corresponding linear track (46) of the actuator rod (42) in order to convert a translational movement of the actuator rod (42) into a rotation of the sensor shaft (62).