Steering Feedback Actuator Motor Mounting Design

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Solution Overview

Problem

Steer-by-wire systems lack haptic feedback, making it difficult for drivers to safely navigate and impairing vehicle steerability and driving safety, due to the absence of direct physical feedback from the steered wheels, and existing feedback actuators face challenges with compact design and high drive power requirements during adjustment.

Innovation Solution

A feedback actuator design where the electric motor is fixed to the stationary outer casing, reducing moving mass and drive power needs, with a compact gearbox arrangement outside the inner casing, allowing for a more flexible and safer design with reduced manufacturing costs and increased installation space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the electric motor is integrated inside the inner casing with the drive unit, then the compactness and space-saving arrangement is improved, but the moving mass increases requiring high drive power for rapid adjustment

Engineering Contradiction:
Improvecasing unit volumeVSAvoiddrive power
Core Design Contradiction:
Volume of moving objectVSPower

Solution Approach 1:

The motor is segmented from the moving inner casing and fixed to the stationary outer casing. This separates the drive unit into a stationary component (motor with stator fixed to outer casing) and a moving component (rotor assembly that rotates but does not translate axially), allowing compact integration while minimizing moving mass during telescopic adjustment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The rotor shaft acts as an intermediary element that transmits rotational motion from the motor to the steering spindle through the gear mechanism. This allows the motor to remain stationary while still driving the rotating components needed for steering feedback.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the inner casing is made telescopically adjustable for compact stowage, then the adaptability and space utilization is improved, but movable electrical cables are required increasing system complexity

Engineering Contradiction:
Improvesteering column adjustabilityVSAvoidelectrical cable arrangement
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The motor is extracted from the moving inner casing and mounted on the stationary outer casing. This eliminates the need for movable electrical cables that would otherwise be required to power the motor during telescopic adjustment, as the motor remains stationary and connected to the vehicle's electrical system via fixed connections.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If the stator is fixed to the outer casing while the rotor rotates, then the motor stability is improved, but the gearbox installation space is reduced

Engineering Contradiction:
Improvemotor stabilityVSAvoidgearbox installation space
Core Design Contradiction:
Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The gear mechanism is arranged in a radial dimension around the rotor shaft rather than extending axially. Gears are positioned at different radial distances from the center, utilizing the circular space around the rotating rotor shaft. This three-dimensional radial arrangement provides sufficient gearbox installation space while maintaining motor stability with the stator fixed to the outer casing.

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

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 the compactness and operational safety of the feedback actuator, reducing drive power requirements and eliminating the need for movable electrical cables, while maintaining effective torque transmission and haptic feedback, thus improving driver experience and vehicle steerability.

Implementation Method 1

an electric motor of a drive unit is arranged in an interior of the casing unit, which motor has a stator fixed to the casing unit and a rotatably drivable rotor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4054918B1Feedback actuator for a steering device of a motor vehicle
Publication Date: 2024.10.23 THYSSENKRUPP PRESTA AG
  • EP4054918B1 patent drawingFigure 1~2
  • EP4054918B1 patent drawingFigure 3~4
  • EP4054918B1 patent drawingFigure 5

AI summary

The present invention relates to a feedback actuator (2) for a steering device (1) of a motor vehicle, comprising a casing unit (3) which has an outer casing (31) that can be attached to a motor vehicle, in which outer casing an inner casing (32) is received so as to be telescopically adjustable in the longitudinal direction, in which a steering spindle (33) is rotatably mounted about a longitudinal axis (L), wherein an electric motor (6) of a drive unit is arranged in an interior of the casing unit (31), which electric motor has a stator (61) that is fixed to the casing unit (31) and a rotatingly drivable rotor (62) having a rotor shaft (63) that is coaxial to the longitudinal axis (L), which rotor shaft is coupled to the steering spindle (33) via a transmission (7). In order to improve the operating properties and design adaptation possibilities, according to the invention the stator (61) is fixed to the outer casing (31).