Steer-By-Wire Rack Position Sensing Without Multiturn Sensors

Solution Overview

Problem

Conventional steer-by-wire steering systems lack a reliable and cost-effective method to determine the steering rack position, necessitating complex and costly sensor setups that are prone to failure.

Innovation Solution

A steer-by-wire steering system design that includes a gear wheel coupled to the steering angle pinion, covering a complete steering range without requiring multiturn sensors, utilizing a magnetic sensor and a cover to protect components, and ensuring a zero-play arrangement between the gear wheel and steering angle pinion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional angle sensors are used to determine steering rack position, then measurement capability is provided, but the system becomes cost-intensive and requires multiple sensors increasing complexity

Engineering Contradiction:

Improvesteering rack position determinationVSAvoidsensor quantity and circuit board area

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the position determination function from complex sensor systems and implements it through a simple gear wheel mechanism coupled to the steering angle pinion. The gear wheel's rotation directly indicates the steering rack position, eliminating the need for multiple angle sensors and their associated circuitry.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces conventional electronic angle sensors with a mechanical gear wheel system. The gear wheel, coupled to the steering angle pinion, provides position information through its rotation, substituting complex electronic measurement systems with a simpler mechanical approach that is inherently more reliable and cost-effective.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If multiturn sensors are used to calculate steering rack position from relative motion, then position determination is achieved, but the system requires at least two sensor transmitters and two sensor receivers increasing component count

Engineering Contradiction:

Improvesteering rack position calculationVSAvoidnumber of sensor transmitters and receivers

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts the position determination function from complex sensor systems and implements it through a simple gear wheel mechanism coupled to the steering angle pinion. The gear wheel's rotation directly indicates the steering rack position, eliminating the need for multiple angle sensors and their associated circuitry.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The gear wheel system is self-sufficient for position determination. The gear wheel's rotation automatically provides position information without requiring additional sensor transmitters or receivers, making the system self-service and eliminating the need for complex multi-sensor configurations.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If conventional angle sensors are used, then position measurement is provided, but the sensors lose position information when de-energized requiring retraining

Engineering Contradiction:

Improveposition measurementVSAvoidposition retention after de-energization

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces conventional electronic angle sensors with a mechanical gear wheel system. The gear wheel, coupled to the steering angle pinion, provides position information through its rotation, substituting complex electronic measurement systems with a simpler mechanical approach that is inherently more reliable and cost-effective.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The gear wheel is preliminarily positioned and coupled to the steering angle pinion during system assembly, establishing a permanent mechanical link that maintains position information without requiring power. This preliminary mechanical configuration ensures position retention even after de-energization, eliminating the need for sensor retraining.

Inventive Principle:

Principle #10Preliminary action

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

Enables precise and economical determination of the steering rack position, enhancing operational safety by eliminating the need for multiple sensors and reducing component failure risks.

Implementation Method 1

a gear wheel (8) coupled to the steering angle pinion (14) for determining an initial position of the steering rack (4)

Methodology Applied

Scientific EffectGear transmission: Gear

Implementation Method 2

utilizing a magnetic sensor

Methodology Applied

Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentUS20250353541A1Steer-by-wire steering system for a motor vehicle

Publication Date: 2025.11.20 VOLKSWAGEN AG

AI summary

A steer-by-wire steering system for a motor vehicle, comprising: a steering rack for transmitting a steering movement to wheels of the motor vehicle, a steering motor for driving a steering movement, a steering gear having a steering angle pinion for transmitting the steering movement of the steering motor to the steering rack, a gear wheel coupled to the steering angle pinion for determining an initial position of the steering rack when the motor vehicle is started. The gear wheel is configured relative to the steering angle pinion and arranged inside the steer-by-wire steering system in such a way that the gear wheel covers a complete steering range of the steering rack when the steering rack is moved over the steering angle pinion.