Power Steering Torsion Bar Torque Sensing With Fewer Sensors

Solution Overview

Problem

Existing electrohydraulic power steering systems for motor vehicles are complex, requiring numerous components and sensors, and occupy significant space, making them difficult to produce and maintain, particularly in tight conditions like low-floor vehicles.

Innovation Solution

The method utilizes the existing torsion bar of the hydraulic steering assistance system to determine driver torque, minimizing the need for additional components and sensors by integrating a sensor arrangement and control unit to calculate driver torque based on the torsion bar's characteristics and motor sensor data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a TAS sensor with additional torsion bar and shaft is used to determine driver torque, then measurement precision is improved, but device complexity increases and installation space requirement increases

Engineering Contradiction:

Improvedriver torque measurementVSAvoidnumber of components and sensors

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the torsion bar of the hydraulic steering assistance system serve dual purposes: it continues to provide hydraulic steering assistance while simultaneously functioning as the sensing element for driver torque measurement. The existing torsion bar's deformation is used by the sensor arrangement to determine driver torque, eliminating the need for separate measurement components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the hydraulic steering assistance function and the driver torque measurement function into a single integrated system. The torsion bar and sensor arrangement that were previously separate components are merged, where the same mechanical element serves both hydraulic actuation and torque sensing purposes.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If a TAS sensor with additional torsion bar and shaft is used to determine driver torque, then measurement precision is improved, but installation space requirement increases

Engineering Contradiction:

Improvedriver torque measurementVSAvoidinstallation space

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent makes the torsion bar of the hydraulic steering assistance system serve dual purposes: it continues to provide hydraulic steering assistance while simultaneously functioning as the sensing element for driver torque measurement. The existing torsion bar's deformation is used by the sensor arrangement to determine driver torque, eliminating the need for separate measurement components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the hydraulic steering assistance function and the driver torque measurement function into a single integrated system. The torsion bar and sensor arrangement that were previously separate components are merged, where the same mechanical element serves both hydraulic actuation and torque sensing purposes.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If numerous components and sensors are used in the power steering system, then driver torque measurement capability is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improvetorque measurement capabilityVSAvoidproduction complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent makes the torsion bar of the hydraulic steering assistance system serve dual purposes: it continues to provide hydraulic steering assistance while simultaneously functioning as the sensing element for driver torque measurement. The existing torsion bar's deformation is used by the sensor arrangement to determine driver torque, eliminating the need for separate measurement components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the hydraulic steering assistance function and the driver torque measurement function into a single integrated system. The torsion bar and sensor arrangement that were previously separate components are merged, where the same mechanical element serves both hydraulic actuation and torque sensing purposes.

Inventive Principle:

Principle #5Merging (Combining)

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 approach simplifies the design, reduces the number of mechanical components, and allows for compact power steering assemblies suitable for tight space conditions, enhancing production efficiency and maintenance simplicity.

Implementation Method 1

a torsion bar (5) between the input shaft (2) and the output shaft (1) for actuating a rotary slide valve

Methodology Applied

Scientific EffectTorsion: Torque

Data Source

PatentUS12491938B2Measurement of driver torque and steering angle in a torque overlay steering system

Publication Date: 2025.12.09 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH

AI summary

A method for determining a driver torque of a power steering assembly for an electrohydraulic power steering system of motor vehicles, includes an input shaft for introduction of a driver torque, an output shaft for driving a steering linkage and a torsion bar between the input shaft and the output shaft for actuation of a rotary slide valve, an electric drive for electrical steering assistance, and a control unit for controlling the electric drive. The power steering assembly has a sensor arrangement on the torsion bar for actuation of the rotary slide valve. An actual torque is determined with the aid of the sensor arrangement. The control unit determines a driver torque with the aid of the actual torque.