Steerable Wheel Assembly for Railway Track Alignment
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Solution Overview
Problem
Track-bound vehicles, especially low-floor trams, experience increased wheel wear and noise due to misalignment of wheels with the railway track, particularly in curves, leading to material fatigue and enhanced friction, which existing steering solutions often exacerbate in straight sections.
Innovation Solution
A steerable wheel assembly with a cross-member and interconnected hubs, featuring sensors and actuators that adjust the wheel's steering angle based on real-time position data from sensors positioned relative to the rail, ensuring optimal alignment and reducing wear and noise across various track conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional fixed wheel alignment is used, then the structure is simple and reliable, but wheel wear and noise increase significantly in curves due to misalignment
Solution Approach 1:
The wheel assembly incorporates steerable wheels that can dynamically adjust their alignment angle relative to the track. The steering mechanism allows the wheel plane to rotate about a vertical steering axis, enabling the wheels to adapt their orientation in response to track curvature changes, thereby reducing misalignment wear in curves while maintaining manageable structural complexity through controlled degrees of freedom
Solution Approach 2:
The system employs sensors (such as inductive sensors or distance sensors) that detect the lateral position of the wheel relative to the track and provide feedback to a control system. This feedback enables real-time adjustment of the steering angle to optimize wheel-track alignment, reducing wear while the control algorithm manages the complexity by using measured position data to determine appropriate steering corrections
2Loss of substance
If steerable wheels are implemented to reduce curve wear, then wheel alignment in curves improves, but wheel adhesion and noise increase in straight track sections
Solution Approach 1:
The steering mechanism dynamically adjusts the wheel alignment based on real-time track conditions. In straight sections, the control system maintains the wheels in a neutral or slightly converged position to ensure proper adhesion and minimize noise, while in curves it actively steers the wheels to optimize alignment. This dynamic adaptation resolves the contradiction by allowing the system to exhibit different behavioral modes appropriate to each track section type
Solution Approach 2:
The system changes the steering angle parameter in response to detected track curvature. In straight sections, the steering angle is maintained at or near zero to preserve optimal adhesion characteristics and minimize noise generation. When curves are detected by sensors, the steering angle is adjusted to reduce misalignment wear. This parameter modulation allows the system to avoid the harmful effects in straight sections while achieving wear reduction in curves
3Ease of operation
If smaller wheels are used in low-floor vehicles to increase passenger comfort and inner space, then floor continuity improves, but wheel load increases leading to enhanced material fatigue and rift formation
Solution Approach 1:
The steerable wheel assembly allows smaller wheels to be used in low-floor vehicles while compensating for increased loads through active alignment control. By dynamically adjusting the steering angle to optimize wheel-track contact, the system reduces lateral friction and misalignment forces that contribute to material fatigue. This enables the use of smaller, lighter wheels that provide better passenger comfort and inner space while maintaining durability through reduced stress from improved alignment
Solution Approach 2:
Sensors monitor the wheel position and track geometry, providing feedback that enables the control system to optimize wheel alignment in real-time. This feedback mechanism reduces lateral forces and uneven loading on the smaller wheels, thereby decreasing material fatigue and the risk of rift formation. The system compensates for the reduced structural margin of smaller wheels through continuous optimization of contact conditions
Data Source
AI summary
The invention concerns a vehicle guided on a railway track comprising a chassis and at least one wheel assembly interconnected to the chassis and a method for steering said vehicle. The wheel assembly comprises a cross-member having a first end to which a first hub is interconnected by a first steering joint and a second end to which a second hub is interconnected by a second steering joint. A first wheel is attached to the first hub rotatable around a first rotation axis and a second wheel is attached to the second hub rotatable around a second rotation axis. A first sensor determines the lateral position of the first sensor with respect to the rail. The first sensor is attached to the first hub and is, with respect to a direction of travel arranged in front of the supporting area of the first wheel in a horizontal direction spaced a distance A1 apart. The first sensor is interconnected to an actuator by a control unit which calculates a steering angle for the at least one interconnected wheel depending on the determined position of the first sensor.