Rail Sensor Device With Opposing Magnetic Flux
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Solution Overview
Problem
Existing sensor devices for detecting wheels on rails face challenges in reliability and sensitivity, particularly when signal levels are low and interference from rail currents and magnetic fields is significant.
Innovation Solution
The sensor device incorporates an additional transmission coil between the existing transmission coils, fed with the same AC voltage but with opposing magnetic flux, and receiving coils connected in series with opposite directions to enhance signal overlap and sensitivity, while suppressing external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two transmitting coils are arranged one behind the other on one side of the guide rail, then the sensor device can detect wheel movement, but the signal overlap between receiving devices is insufficient and sensitivity is reduced
Solution Approach 1:
The transmitting side is segmented into three separate transmitting coils (first, second, and third transmitting coils) arranged in sequence along the guide rail. Each coil generates magnetic flux that contributes to the overall magnetic field, creating multiple signal paths that improve signal overlap between receiving devices and enhance detection sensitivity.
Solution Approach 2:
The magnetic fluxes from all three transmitting coils are combined to create a composite magnetic field that provides consistent signal coverage. The receiving coils on both sides of the guide rail simultaneously detect the combined magnetic flux changes, merging multiple signal contributions to improve reliability and sensitivity.
2Reliability
If receiving coils are connected in series with opposite directions, then external interference from rail currents and magnetic fields is suppressed, but the device complexity increases
Solution Approach 1:
The opposite direction connection of receiving coils converts the harmful effect of external interference (rail currents and magnetic fields) into a beneficial cancellation effect. Since external interference affects both coils equally, connecting them in opposite directions causes the interference signals to cancel each other out, while the differential magnetic flux from wheel movement is amplified.
Solution Approach 2:
The receiving coils are connected asymmetrically in opposite directions rather than in the same direction. This asymmetric connection creates differential signaling that inherently rejects common-mode interference while preserving the differential signal from the wheel movement, improving reliability without requiring additional complex filtering circuits.
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 configuration increases the reliability of wheel detection by enhancing signal overlap and sensitivity, particularly in low signal conditions, and effectively compensates for external interference such as rail currents and magnetic fields.
Implementation Method 1
two transmitting coils supplied with an alternating voltage... the magnetic flux generated by the at least one further transmitting coil
Implementation Method 2
two receiving devices, each with two receiving coils connected in series in opposite directions... for detecting a wheel moving along a guide rail
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a sensor device for detecting a wheel moving along a rail (60). The sensor device is equipped with two transmission coils (11, 12) on one side of the rail (60), said transmission coils being supplied with an alternating voltage and being arranged one behind the other with respect to a longitudinal direction of the rail (60), and with two receiving devices (31, 35) on the other side of the rail (60), each receiving device comprising two receiving coils (32, 33; 36, 37) which are connected together in series in opposite directions and which are arranged one behind the other with respect to the longitudinal direction of the rail (60). According to the invention, the sensor device is designed such that the sensor device has at least one additional transmission coil (13) on one side of the rail (60), said transmission coil being arranged between the transmission coils (11, 12) with respect to the longitudinal direction of the rail (60); the transmission coils (11, 12) and the at least one additional transmission coil (13) are supplied with an alternating voltage of the same frequency; and the magnetic flux (23) generated by the at least one additional transmission coil (13) is oriented opposite the magnetic fluxes (21, 22) generated by the transmission coils (11, 12).