Steering Unit Spindle Drive Integral End Stop

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Solution Overview

Problem

Existing steer-by-wire steering systems for motor vehicles lack a simple and economical method to limit the steering angle, which is crucial for providing a haptic feedback to the driver.

Innovation Solution

A steering unit with a spindle drive that includes a spindle and a spindle nut, where the spindle nut is displaced axially to limit the steering angle by tangentially striking against an end stop formed integrally with the spindle, eliminating the need for a separate mechanical coupling to the wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate disc is attached to the spindle via a separate fixing system to form the end stop, then the steering angle can be limited, but the number of components increases and the structure becomes more complex

Engineering Contradiction:

Improvesteering angle limitationVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The end stop is merged with the spindle by forming it integrally as a single piece. The spindle (18) includes a first end stop (24) that is formed integrally with the spindle, eliminating the need for a separate disc attached via a fixing system. This reduces the number of components and simplifies the structure while maintaining the steering angle limitation function.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The spindle serves multiple functions: it converts rotational movement to axial movement of the spindle nut, and it provides the end stop function through its integral first end stop (24). This multi-functionality reduces the need for separate components and simplifies the overall structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a separate disc is attached to the spindle via a separate fixing system to form the end stop, then the steering angle can be limited, but the production and mounting complexity increases

Engineering Contradiction:

Improvesteering angle limitationVSAvoidproduction and mounting complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If the steering shaft is made shorter and more compact without mechanical coupling to the wheels, then the steering unit becomes more compact, but the haptic feedback of maximum steering deflection cannot be perceived

Engineering Contradiction:

Improvesteering shaft lengthVSAvoidhaptic feedback

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The spindle drive acts as an intermediary mechanism that translates the rotational movement of the steering shaft into axial movement of the spindle nut. The end stop (24, 26) provides a mechanical limit that creates haptic feedback for the driver, simulating the feeling of maximum steering deflection even though there is no direct mechanical coupling to the wheels.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The direct mechanical coupling between the steering shaft and wheels is replaced by a sensor-based system with an electric actuating drive. The haptic feedback is maintained through the spindle drive mechanism with end stops that provide mechanical limits, combining electronic control with mechanical feedback elements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution allows for a compact, low-cost steering unit that effectively limits the steering angle, providing a haptic feedback to the driver similar to a mechanical steering system while reducing complexity and production costs.

Implementation Method 1

a spindle drive which cooperates with the steering shaft to limit a steering angle of the steering shaft, wherein the spindle drive has a spindle and a spindle nut screwed onto the spindle, wherein the spindle nut is displaceable relative to the spindle with a movement component in the axial direction when the spindle is rotated

Methodology Applied

Scientific EffectScrew thread mechanism: Screw

Data Source

PatentUS20250121873A1Steering unit for a steer-by-wire steering system of a motor vehicle

Publication Date: 2025.04.17 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

The disclosure relates to a steering unit for a steer-by-wire steering system of a motor vehicle, having a steering shaft which can be rotated by a driver, and a spindle drive which interacts with the steering shaft to limit a steering angle of the steering shaft, wherein the spindle drive has a spindle and a spindle nut screwed onto the spindle, wherein the spindle nut is displaceable with a movement component in the axial direction relative to the spindle when the spindle is rotated, wherein the spindle nut has a first spindle stop for tangentially striking against a first end stop fixed to the spindle, wherein the first end stop is formed integrally with the spindle. The number of components is thus reduced, and the structure of the steering unit is simplified, as a result of which the effort for production and assembly is reduced, and cost-effective production of the steering unit is made possible.