DESC:Field of the invention
The present invention relates generally to the field of optical device, more particularly, a method of dynamic temperature monitoring system using Fiber optic sensors. The area of concern of this system is monitoring the temperature of axle boxes of railway vehicle for their safe operation.
Background
An Axle box is a device to support weight of the vehicle and transfer this weight to the wheel. The Axle box consists of housing with removable front cover, bearings, lubrication system, sealing to prevent dust, fixture to support the suspension of vehicle, earthing etc.
Hot box is the term used when an axle bearing overheats due to inadequate wheel-bearing lubrication or mechanical flaws (bearing failure) in railway vehicle. Overheating or increase in temperature indicates defective axle or inadequate lubrication in the axle, which in extreme situation may cause derailment or fire. Currently, hot axle is detected by listening to the whistle sounds of wheel bearing during running mode of vehicle. It is also detected by grease oozing out, physical touch, visually by discolouration of axle boxes or a handheld non-contact IR device by a technician, when the vehicle stops.
With the rapid development of high-speed railways, there is need for real time and dynamic monitoring of axle box temperature and triggering an alarm to the driver, guard or other authority regarding any hot axle during run time of train. Real time monitoring of the axle box temperature will not only ensure safety but also save on the time taken for manual inspection and help in reducing maintenance cost.
The Published Article, 2012 International Conference on Intelligent System Design and Engineering Application, IEEE Computer society, entitled “Real-Time Fault Diagnosis of Train Bogie using FBG sensors” to measure the temperature profile of various critical parts- axle and motor Bearing, Gear Box bearing and Braking Mechanism on a train Bogie and fore-warns the train driver. The system installed eighteen FBG sensors, interrogation system, data processing with GUI to diagnose the fault in particular part. But, the system is too complicated and able to monitor the fault in a single train bogie at a time.
The Application No. KR20130060816A, entitled “Monitoring System and method for Railway Car Axle using FBG sensors” relates to a continuous train monitoring system and method for measuring temperature and vibration generated on the train axis using FBG strain gauge and FBG thermometer. The invention also provides wireless remote connection of measurement information during train operation. But, the sensors are mounted inside the shaft cap which is fastened on the shaft and real time data is not transmitted to on board user.
The Application No. CN 104608796B, entitled “A vehicle axle temperature alarm system and set of movable implementations” relates to a system and method to provide a real time display of vehicle axle temperature with alarm system. The application includes temperature acquisition unit, temperature detecting unit and display unit to take signals, process the signals and display at monitor screen. The acquisition unit with PT100 sensor monitors the temperature by variation in resistance value of sensor to measure temperature. But PT100 is platinum resistance thermometer which is known to cause false alarms, is not self-powered and unsuitable for high temperature applications.
Therefore, an apparatus, method and system for real time monitoring of axle box temperature to ensure safety with reduced maintenance costs and man power requirement, wheel protection, fast monitoring, and provisions for logging temperature data for future references is highly desired.
Summary of invention
The present invention fulfils the foregoing needs by providing an optical fiber sensing based alarm system and monitoring vehicle axle box temperature in real time. The system includes FBG sensor mounted on the axle box, the bearing housing of the railway bogey. The sensor is connected to an optical interrogation system using optical fiber cable. The instrument sends in input light signal to the sensor and interrogates the reflected optical signals. When the wheels move at higher speed, the axle box gets heated and the FBG sensors receive stress and cause a shift in Bragg wavelength. A Data processing unit (DPU) converts the corresponding shift in wavelength to temperature and displays the results at Graphical user interface (GUI) of the server.
The Bragg wavelength value directly corresponds to the temperature of axle box or bearings through young’s modulus of the fiber and by monitoring the temperature value, the wheel health can be monitored in real time.
When the temperature is elevated in axle box bearing, the interrogator analyses the signal, data processing unit (DPU) process the corresponding shift in wavelength and displays the results at Graphical user interface (GUI) of the server and generates an alarm signal.
Hence a modular design with auditory and visual characteristic is leveraged to monitor the temperature of axle box of railway vehicle. The real time monitoring and alarm system provides train safety.
Brief description of figures
Exemplary embodiments of the present invention are fully explained with the description below and the accompanying figures, wherein:
Figure1: Illustrate System architecture.
Figure2: shows the front view of inserting sensor on axle box bearing.
Figure3: shows rise in temperature of axle box with respect to time during running mode.
Detailed description of invention
The foregoing description of the embodiments, the various features, and advantageous details of the invention has been presented for the purpose of illustration. It is not intended to be exhaustive or to limit the invention to the precise form disclosed as many modifications and variations are possible in light of this disclosure for a person skilled in the art in view of the figures and description. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by person skilled in the art.
The embodiments herein below provide an optical fiber sensing based system for monitoring the temperature of axle box in railway coaches. The system and method for monitoring temperature of axle box bearing using FBG sensors in real time is explained.
Fig 1 illustrates the system architecture and includes FBG sensor 101, Optical interrogator 102, data processing unit (DPU) 103, Ethernet switch 104 and the server 105.
The optical fiber with fiber Bragg grating (FBG) as shown in fig.1, is obtained by periodically modulating the refractive index of the core of single mode optical fiber using laser beam. At this interface, one particular wavelength of light is reflected, called Bragg wavelength, depending on the effective refractive index of the fundamental mode propagating through the fiber and period of the grating/modulation.
Further in fig1, optical interrogator 102 acts as a light source for optical fiber with FBG sensors 101 and also receives and analyses the reflected light from FBG sensor 101.
Data processing unit (DPU) 103 processes all the information received from optical interrogator 102 and then server 105 stores displays the processed result.
Fig 2 shows the mounting of FBG sensor on Axle Box bearing. The control arm 201 is connecting axle bearing 203 to the bogie frame and transmitting forces. Primary suspension 202 is two units of two steel coil springs laid out on control arm 201 upper part. The FBG sensor 204 is pasted on the bearing of axle box 203 to monitor their temperature and display the result at GUI device of authorized users.
Fig 3 shows the rise in temperature of axle box with respect to time. During running mode of train, there is a change in Bragg wavelength of the sensor, as axle bearings get heated. This shift in wavelength is converted in to shift in temperature of sensor. This temperature shifting of sensor is display as rise in temperature of bearing housing Axle box.
Experimentation of Temperature Monitoring
In one embodiment the temperature monitoring system, FBG sensors are placed with axle box bearing of every coach. The sensor is sensing the variation in Bragg wavelength with respect to time in real time. Optical interrogator analyses the change in refractive index through shift in Bragg wavelength with respect to time for different temperature. DPU converts the shift in Bragg wavelength to corresponding temperature on the sensor due to the temperature in variation on axle box. With the proposed system various experiments were conducted (as shown in fig.3) to calculate temperature of axle box.
When the train started its journey, the axle box temperature was the same as the ambient temperature and the temperature rise is recorded as 0?. As the train started moving, it was observed that the temperature of axle box increased rather steeply.
This GUI provides visualization of bearing housing axle box in every coach for driver or any railway authority. Hence, the proposed system provides closed loop-based monitoring of Axle box temperature using FBG in real time to reduce maintenance and man power issues. The proposed system improves train safety during running mode of railway vehicle.

,CLAIMS:We Claim
1. A method for real time monitoring of temperature of axle box of railway vehicle, comprising:
providing a sensing device for producing a signal corresponding to heating of axle box;
mounting said sensing device on to axle box of wheel of every coach;
heating of axle box create stress and shift in Bragg wavelength of said sensing device;
analysing shift in Bragg wavelength of said sensing device;
converting shift in Bragg wavelength to temperature shift on to said sensing device and display corresponding rise in temperature of axle box of each wheel at server.
2. The method for real time monitoring of temperature of axle box as claimed in claim1, wherein said strain sensing device is inserted into bearing of axle box of the wheel of every coach.
3. The method for real time monitoring of temperature of axle box as claimed in claim 2, wherein said sensing device is inserted using industrial glue and steel tape.
4. The method for monitoring the temperature of axle box as claimed in claim1, wherein at least one temperature sensing device is mounted on the bearings of axle box correspond to each wheel of the coach.
5. A measuring device for real time monitoring of temperature of axle box of railway vehicle, measuring device comprising:
sensors means positioned on axle box bearing;
stress means on said sensing unit producing signal leads to shift in Bragg wavelength;
analyzer and processor means connected with said sensing unit means for analysing, processing of wavelength shift in to corresponding axle box heating; and
display temperature of axle box of each wheel at GUI device/server.
6. A system for real time monitoring of temperature of axle box of railway vehicle, comprising:
a sensor inserted on bearings of axle box of the wheel of every coach;
an optoelectronic instrument to analyse change in Bragg wavelength due to strain;
a data processing unit (DPU) to process change in Bragg wavelength and generate data continuously;
GUI of authorized person displays rise in temperature vs time corresponds to heating of axle box; and
an alarm system to generate warning to driver when axle box temperature rise above a fixed threshold.
7. The system for real time monitoring of temperature of axle box of railway vehicle as claimed in claim 6, wherein authorized person is the person having login ID and password.
8. The system for real time monitoring of temperature of axle box of railway vehicle as claimed in claim 6, wherein an authorized person remotely monitors current temperature with respect to rise in heating effect of axle bearings.
9. The system for real time monitoring of temperature of axle box of railway vehicle as claimed in claim 6, wherein sensor is Fiber Bragg grating (FBG) sensor.