Rail Track Magnetic Sensor for Train Wheel Direction Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the direction of motion of a train wheel on a rail track are inadequate, particularly in non-electrified marshalling yards lacking safety systems, as they cannot accurately discern the direction of passing trains using single sensors like Hall effect devices, and multiple sensors are cumbersome.
Innovation Solution
A method utilizing a magnetic field sensor to detect changes in magnetic field values caused by stress on the rail via the wheel, employing the Villari effect, which senses changes in two orthogonal directions to determine the direction of motion, with a device placed at the neck of the rail track for reliability and compactness, and using a bias magnetic field for improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single Hall effect device is used to detect wheel passage, then the device complexity is reduced, but the ability to determine direction of motion is lost
Solution Approach 1:
The patent transitions from detecting only the presence of a wheel (single dimension) to detecting both presence and direction of motion (multiple dimensions). By measuring magnetic field changes in two orthogonal directions (x and y axes) using a single multi-axis sensor, the system captures directional information without requiring multiple separate sensors, thus resolving the contradiction between device simplicity and information completeness.
2Measurement precision
If multiple sensors are used to determine direction of motion, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple sensing capabilities into a single multi-axis magnetic field sensor. Instead of using separate sensors for different measurement directions, the invention integrates x-axis and y-axis magnetic field detection functions into one device, thereby maintaining high measurement precision for direction determination while reducing overall device complexity and the number of components required.
3Measurement precision
If the sensor is placed near the head of the rail track, then the detection sensitivity is improved, but the reliability of the device is reduced due to exposure to passing trains
Solution Approach 1:
The patent introduces the neck of the rail as an intermediary location that transmits the mechanical stress from passing wheels to the sensor. By placing the sensor at the neck rather than directly near the head, the system maintains detection sensitivity through the transmitted stress signals while improving reliability by positioning the device in a less exposed area, away from direct contact with passing trains.
4Reliability
If the sensor is placed at the neck of the rail, then the reliability is improved, but the detection sensitivity may be reduced
Solution Approach 1:
The patent utilizes the dynamic transmission of mechanical stress through the rail structure. When a wheel passes, the stress dynamically propagates from the contact point through the neck to the sensor location. This dynamic stress transmission ensures that even though the sensor is positioned at the neck (improving reliability), it still receives sufficient mechanical input to detect magnetic field changes with adequate sensitivity, thus resolving the contradiction between reliability and detection capability.
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 method provides accurate and reliable determination of the direction of motion with reduced exposure to passing trains and environmental influences, enabling efficient power usage and wireless operation over extended periods.
Implementation Method 1
a magnetic field is induced by the force introduced onto the rail, which is typically manufactured from a ferromagnetic material, e.g. steel. This effect is known as the Villari effect or the inverse magnetostrictive effect. This effect can be described as the change of the magnetic susceptibility of a material when subjected to a mechanical stress.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Method for determining a direction of motion of a wheel of a passing train on a rail track, the method comprising: - sensing, in at least a first and a second direction different from the first direction, a change in a magnetic field value caused by stress exerted on the rail via the wheel of the passing train, wherein the magnetic field value is indicative for a change in a flux density of a magnetic field originating from the rail track, wherein the sensing comprises - obtaining a first signal associated with the wheel comprising a first plurality of the magnetic field values for the first direction for respective times from the magnetic field sensor, and - obtaining a second signal associated with the wheel comprising a second plurality of the magnetic field values for the second direction for respective times from the magnetic field sensor; and - determining the direction of motion of the passing wheel on the basis of the obtained first signal and second signal.