Active Wheelset Steering for Rail Traction Loss

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Rail vehicles, particularly freight locomotives, experience significant loss of traction in track curves and inclines due to reduced friction between the driven track wheel and the rail, leading to difficulties in starting up under unfavorable conditions such as soiled or wet rails, which existing solutions like using oversized locomotives or sanding do not adequately address.

Innovation Solution

The method involves actively steering the track wheels to improve friction conditions by adjusting their radial and axial positions, using hydraulic, pneumatic, mechanical, or electromechanical means, to optimize contact geometry and increase the friction coefficient, thereby enhancing traction without resorting to oversized locomotives or sanding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rail vehicle uses conventional drive control in a curve, then the drive output is limited to prevent wheel spinning, but the traction is reduced by around 10% due to loss of traction

Engineering Contradiction:

Improvetraction reliabilityVSAvoiddrive output

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamic steering of the wheelset by actively changing the steering angle of the wheelset relative to the track curve radius. The steering angle is dynamically adjusted based on the detected curve radius, allowing the wheelset to optimally follow the curve while maintaining favorable contact conditions between the wheel and rail, thus preventing traction loss without limiting drive output.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback by detecting the actual curve radius during operation and using this information to adjust the steering angle of the wheelset. This closed-loop control ensures that the wheelset maintains the optimal steering angle adapted to the specific curve conditions, compensating for traction loss in real-time.

Inventive Principle:

Principle #23Feedback

2Force

If a heavier locomotive is used to increase traction, then the traction capability is improved, but the device complexity and cost increase

Engineering Contradiction:

Improvetraction forceVSAvoidlocomotive configuration

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

Instead of changing the physical mass of the locomotive, the patent changes the operational parameters by actively adjusting the steering angle of the wheelset. This parameter change allows the existing locomotive to achieve optimal traction by modifying how the wheelset contacts the rail in curves, avoiding the need for a heavier locomotive.

Inventive Principle:

Principle #35Parameter changes

3Force

If sanding is used to improve friction conditions, then the friction coefficient is increased, but the manufacturing precision and rail surface quality are degraded

Engineering Contradiction:

Improvefriction forceVSAvoidrail surface quality

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediary mechanism - the active steering system - that mediates between the wheelset and the rail. By adjusting the steering angle, the system creates favorable contact conditions that increase friction without physically altering the rail surface, thus avoiding the degradation caused by sanding while still improving friction force.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If the wheelset steering angle is actively adjusted in a curve, then the contact geometry is optimized and traction is improved, but the device complexity increases due to additional steering mechanisms

Engineering Contradiction:

Improvetraction efficiencyVSAvoidwheelset steering system

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical steering mechanisms with a more streamlined system that uses detected curve radius information to control the steering angle. The solution substitutes elaborate mechanical linkages with a control system that adjusts the steering based on measured parameters, reducing mechanical complexity while maintaining traction efficiency.

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 approach effectively compensates for the loss of traction, reducing rail wear and maintaining efficient drive output, even in challenging conditions, by optimizing contact points and friction coefficients, thus ensuring reliable start-up and operation in curves and inclines.

Implementation Method 1

at least one of the bearings of each triangular link has a hydraulic bushing with variable longitudinal stiffness, wherein the hydraulic bushing comprises at least one fluid chamber that is fillable with a hydraulic fluid, such that a hydraulic pressure, via which the longitudinal stiffness of the hydraulic bushing is settable, can build up in the fluid chamber

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentUS11285976B2Method for compensating for a loss of traction of a rail vehicle

Publication Date: 2022.03.29 SIEMENS MOBILITY GMBH

AI summary

A method for compensating for a loss of traction of a rail vehicle, preferably a freight locomotive, in a track curve, is particularly pertinent when the rail vehicle is starting up and/or is on an incline. Comparably unfavorable frictional conditions between a track and at least one driven track wheel of the rail vehicle are changed into comparably favorable frictional conditions by actively steering the track wheel on the rail.