Rail Vehicle Drive Coupling for Arc-Free Motor Disconnection

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Solution Overview

Problem

In railway vehicle drive devices with electric motors, power supply faults can lead to unpowered motor drives continuing to rotate due to inertia, potentially causing electric arcs that damage the motor or its environment.

Innovation Solution

A mechanical coupling system with an electromagnetic actuator and an elastic member is used to disconnect the motor from the wheels in case of a power fault, preventing electric arcs by ensuring the slide moves to a withdrawal position when the electromagnetic actuator is deactivated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the motor remains connected to the wheels during power supply faults, then the motor can continue to rotate using wheel inertia, but this generates electric arcs that damage the motor and cause safety hazards

Engineering Contradiction:
Improvemotor safetyVSAvoidelectric arc generation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coupling means are designed to be dynamically changeable between engaged and disengaged states. The slide moves along the hub to establish or break the mechanical connection between drive shaft and axle, allowing the system to adapt its configuration based on operational conditions and prevent harmful electric arcs when needed

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The slide acts as an intermediary element between the drive shaft and axle. It can be positioned to either transmit power through engagement with the pinion or prevent power transmission through disengagement, thereby controlling the mechanical connection state to eliminate electric arc generation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the electromagnetic actuator is used to engage the slide, then the motor can be reliably connected to the wheels during normal operation, but the system complexity increases due to additional actuation mechanisms

Engineering Contradiction:
Improvemechanical connection reliabilityVSAvoidcoupling system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The elastic member provides automatic return function, pushing the slide back to the disengaged position when the electromagnetic actuator is de-energized. This self-service mechanism eliminates the need for additional actuation components to maintain the disengaged state, reducing overall system complexity while ensuring reliable engagement/disengagement cycles

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If the slide is designed to move along the hub between engaged and retracted positions, then the motor can be disconnected from the wheels to prevent electric arcs, but the device complexity increases due to the movable coupling mechanism

Engineering Contradiction:
Improveelectric arc preventionVSAvoidcoupling mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The coupling means are designed to be extractable or separable. The slide can be moved to a retracted position where it disengages from the pinion, effectively taking out the mechanical connection between motor and wheels. This extraction capability allows the system to eliminate harmful electric arcs by removing the power transmission path

Inventive Principle:
Principle #2Taking out (Extraction)

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

Effectively prevents the generation of electric arcs during power supply failures, ensuring motor safety and preventing potential fires by mechanically disconnecting the motor from the wheels.

Implementation Method 1

an electromagnetic actuator powered by means of the electrical circuit, configured to apply a first force moving the slide towards its engagement position when it is activated

Methodology Applied
Scientific EffectElectromagnetic force: Electromagnetic Induction

Implementation Method 2

an elastic member for returning the slide towards its retracted position, applying a second force moving the slide towards its retracted position

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 3

the motor, connected to the wheels, remains rotated by the inertia effect of the wheels

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP4484245A1Vehicle drive device, in particular for a rail vehicle
Publication Date: 2025.01.01 ALSTOM HOLDINGS SA
  • EP4484245A1 patent drawingFigure 1
  • EP4484245A1 patent drawingFigure 2
  • EP4484245A1 patent drawingFigure 3

AI summary

The drive device includes means (19) for mechanically coupling a drive shaft (18) with an axle, comprising: - a hub (28), fixed to the shaft (18), - a pinion (30), connected to the shaft (18) by a pivot, - a slide (32) fixed in rotation to the hub (28) and movable in translation along the hub (28), between an engagement position of the slide (32) with the pinion (30), and a retraction position of the pinion (30), - an electromagnetic actuator (42) applying a first force moving the slide (32) towards its engagement position when it is activated, and - an elastic element (44) for returning the slide (32) to its retraction position, applying a second force moving the slide (32) towards its retraction position, the second force being less than the first force.