POINT MACHINE, POINT MACHINE MONITORING SYSTEM, USE OF A FIBER OPTIC SENSOR FOR PREDICTIVE MAINTENANCE OF A POINT MACHINE AND METHOD FOR PREDICTIVE MAINTENANCE OF A POINT MACHINE

Abstract

 The invention concerns a point machine comprising:
• a housing and an actuating assembly arranged inside the housing;
• an actuating rod driven by the motor for moving at least one point blade of a point;
• a fiber optic sensor, wherein the fiber optic sensor is directly attached to the point machine for detection of a parameter which indicates the condition of the point machine.

Description

Background of the invention

[0001] The invention concerns a point machine comprising a housing and an actuating assembly with a motor arranged inside the housing, an actuating rod driven by the motor for moving at least one point blade of a point and a fiber optic sensor.

[0002] An according point machine is known from [4].

[0003] Point machines for railway applications are those elements that cause the most delays in a railway network. The point machine moves a point blade, which makes contact with one or another rail and thus enabling a passing train to take one or the other direction. Providing a diagnostic system to detect degradation of point machine and/or turnout functionality can help to keep the infrastructure in operation before an operational impact (delays) occurs.

[0004] Switch diagnosis systems have been suggested to monitor the function of the point machine by monitoring the electrical power consumption during point blade repositioning [1], [2]. Relevant data, like voltage, amperage, and effective power, are directly measured at the engine and then processed in a remote diagnostic component. Yet, this method is not accurate as the motor (the energy consumer) is not directly coupled with the turnout and therefore only gives indirect information about the applied force. Further, measuring the voltage always causes an interference into the electrical circuitry. This triggers a technical safety discussion and approval activities on any system which the measurement is applied to.

[0005] discloses a point inspection system which measures the force directly by using a force measuring bolt with a classic strain gauge force sensor which changes its resistance if it is deformed. Yet, the railway tracks are subjected to various electromagnetic interference. In order to achieve reliable results, the sensor has to be made immune to those electromagnetic interferences which requires further efforts. Further disadvantages of this system is that strain gauge force sensor needs to be powered locally. Outdoor electronics or copper cables for connection are required.

[0006] discloses a dynamic monitoring method and device of a stress sensitization fiber Bragg grating of locking rods of a railway turnout switch machine. A fiber Bragg grating strain gauge is fixed between two semi-circular clamping blocks of each locking rod by means of a screw, the large strain capacity generated by the long distance between the two clamping blocks of each locking rod is applied to the fiber Bragg grating for sensitization through a rigid lengthened arm. When the locking rods of the switch machine work, the system detects the switching force, the intensity and direction of locking force, switching speed etc. and compares the data with values stored in the history to obtain whether the turnout switch machine works normally or not. Yet, due to vibrations the screws which fix the clamping block to the rod tends to get loose which affects the force measurement.

Object of the invention

[0007] It is therefore an object of the invention to provide a point machine, a point machine monitoring system and a method for predictive maintenance which work reliable and with reduced technical effort.

Description of the invention

[0008] This object is solved by a point machine according to claim 1, a point machine monitoring system according to claim 8, the use of a fiber optic sensor for predictive maintenance of a point machine according to claim 9 and a method for predictive maintenance according to claim 10.

[0009] According to the invention the fiber optic sensor is directly attached to the point machine for detection of a parameter which indicates the condition of the point machine.

[0010] Parameters which indicate the condition of the point machine (e.g. degradation) are parameters which allow prediction of a required maintenance operation, e.g. force/stress, vibration, temperature.

[0011] Due to the usage of a fiber optic sensor predictive maintenance can be carried out without electromagnetic interference and without interference with the safe controlling system.

[0012] The fiber optic sensor comprises a sensor fiber and may further comprise a carrier device to which the sensor fiber attached, in particular in a prestressed manner. Thus, the fiber optic sensor is capable of detecting stretching forces as well as compressing forces, thereby enhancing the sensitivity of the fiber optic sensor without gearing mechanism.

[0013] According to the invention the fiber optic sensor is "directly attached", i.e. without any additional mechanical fixing devices. No connecting and gearing devices are used for attachment. The fiber optic sensor directly contacts the point machine and thus measures directly the parameter acting on the point machine. Preferably the fiber optic sensor is attached by means of adhesive bonding. The inventive point machine allows reliable detection of a change of relevant parameters during the life time of the point machine. Thus maintenance operations can be carried out before a critical condition of the point machine (loose parts, broken rod, increased friction, worn bearings, ...) or other adjacent elements (track ballast tamping status, point blade movement, friction on sliding plates (or lift-roll-lower-systems etc.), flat wheels of rolling stock) is reached.

[0014] In a highly preferred embodiment the fiber optic sensor is attached to a non-moving element of the point machine, in particular the housing or a console attached to the housing. This is the most preferred embodiment since the sensor is not moving, which considerably reduces the risk of lifetime reduction. It has been demonstrated that vibration measurements by using a fiber optic sensor directly attached to the console of a point machine show the typical characteristic pattern of a point machine swing. No cable which has to withstand a continuous back and forth movement is required, hence simplifying the cable arrangement. If the fiber optic sensor is used as vibration sensor all noise-vibrations arising from a movement of the part of the point machine to which the sensor is attached can be detected.

[0015] It is most preferred that the sensor is attached to the outside of the housing in order to avoid any safety discussion concerning objects inside of the point machine intruding into the integrity of the mechanics.

[0016] Nevertheless, it is also possible that the fiber optic sensor is directly attached to the actuating rod.

[0017] Further, the actuating rod may comprise a connection section with an eyelet for connecting the actuating rod to the point blade and the fiber optic sensor is arranged within the eyelet. The sensor is then formed as a pin and acts as connection bolt.

[0018] For measuring the strain force applied to the part of the point machine to which the sensor is attached it is highly preferred that the fiber optic sensor is a strain gauge force sensor. I.e. the fiber optic sensor is used for measuring strain on the part of the point machine to which it is attached.

[0019] For detecting loose or broken parts or undefined operations of the point machine at an early stage it is advantageous if the fiber optic sensor is a vibration sensor.

[0020] It is also possible that one fiber optic sensor can function as a vibration sensor as well as a strain gauge sensor. Both functionalities may be used separately or concurrently.

[0021] It is preferred that more than one fiber optic sensor is directly attached to the point machine. Just as the first fiber optic sensor the further fiber optic sensor can be a strain gauge force sensor and/or a vibration sensor and/or a temperature sensor. The different sensors may be attached to different parts of the point machine (e.g. in order to gain information about the load on different parts of the point machine) and/or the different sensors can detect different parameters in order to get additional information (e.g. vibrational information in addition to strain information).

[0022] A highly preferred embodiment of the inventive point machine comprises a strain gauge force fiber optic sensor which is attached to the actuating rod or the housing and a vibration fiber optic sensor which is attached to the housing or to the actuating rod.

[0023] The invention also concerns a point machine monitoring system comprising a point machine as described before, a data acquisition unit which is connected to the fiber optic sensor via a fiber optic cable, a diagnostic system for processing data measured by means of the fiber optic sensor, and means for transmitting of data from the data acquisition unit to the diagnostic system.

[0024] According to the invention a fiber optic sensor is used for predictive maintenance of a point machine, wherein the fiber optic sensor is directly attached to the point machine.

[0025] An according method for predictive maintenance of a point machine is suggested, wherein data is detected by means of a fiber optic sensor; the detected data is transferred to a data acquisition unit via a fiber optic cable. A diagnostic system evaluates whether a maintenance operation is required or not. The detected data are optical signals which are translated to electrical signals by means of the data acquisition unit in order to enable the diagnostic system to interpret the data.

[0026] In a highly preferred variant of the inventive method a frequency analysis is carried out resulting in a (detected) frequency pattern, wherein the detected frequency pattern is compared with a target frequency pattern or with a previously detected frequency pattern. By carrying out a frequency analysis a changing vibration behavior of the point machine can be detected, indicating e.g. loose parts of the point machine, increased friction, worn bearings, ...) or other adjacent elements (track ballast tamping status, point blade movement, friction on sliding plates (or HRS systems etc.), flat wheels of rolling stock).

[0027] In order to determine whether the point blade is locked or unlocked it is advantageous if the frequency pattern is used to determine the direction of movement of a point blade. The point comprises a locking mechanism to lock the point blade in a predetermined position. The locking mechanism causes noise with a known frequency pattern. Thus the movement direction of a point blade and therewith the blocking state of the point can be determined.

[0028] Further advantages can be extracted from the description and the enclosed drawing. The features mentioned above and below can be used in accordance with the invention either individually or collectively in any combination. The embodiments mentioned are not to be understood as exhaustive enumeration but rather have exemplary character for the description of the invention.

Drawings

[0029] The invention is shown in the drawing.

FIG. 1

shows a point machine monitoring system according to the invention with a fiber optic sensor attached to the actuating rod and a further fiber optic sensor attached to the housing of the point machine.

FIG. 2

shows a point machine monitoring system according to the invention with a fiber optic sensor attached within the eyelet of a connection section of the actuating rod and a further fiber optic sensor attached to the housing of the point machine.

FIG. 3

shows a point machine monitoring system according to the invention with a fiber optic sensor attached to a console of the point machine.

[0030] Fig. 1, 2 and 3 show preferred embodiments of the inventive point machine monitoring system. The inventive monitoring system comprises a point machine 1 with an actuating rod 2. The actuating rod 2 is driven by a motor 3 which is located inside a housing 4. The point machine is equipped with fiber optic sensors 5, 6, 7, 8 which are directly attached to components of the point machine, wherein fiber optic sensors 5 and 7 are attached to moving parts of the point machines 1, 1', 1" and further fiber optic sensors 6, 8 are attached to non-moving parts of the point machines 1, 1', 1". The fiber optic sensors 5, 6, 7, 8 each comprise a sensor fiber with a fiber Bragg grating. Light is coupled from a light source (not shown), which can be placed either indoor or in an outdoor cabinet, into the sensor fiber, wherein wavelengths which correspond to the Bragg wavelength of the fiber Bragg grating within a filter bandwidth are reflected by the fiber Bragg grating (detection of an optical signal). Due to forces acting on the part to which the fiber optic sensor is attached the Bragg wavelength of the fiber Bragg grating changes and the wavelength of the reflected light (detected data) changes accordingly. The reflected light is transmitted to a data acquisition unit 9 via fiber optic cables 10. The data acquisition unit 9 translates the detected optical signal into an electrical signal which is then transmitted to a diagnostic system 11 (e.g. via cable or wireless network) which evaluates and interprets the electrical signal to generate different levels of alarms for preventive or corrective maintenance.

[0031] According to the invention the fiber optic sensors are directly attached to the point machine, in particular force locking contacted preferably over the whole bottom area of the fiber optic sensor without any additional mechanical fixing devices or transmission/gearing, thereby enabling reliable sensing of the force acting on the part of the point machine the fiber optic sensor is attached to without being influenced by external disturbances or loose fixing devices.

[0032] The fiber optic sensors can be used as force sensor, temperature sensor and vibration sensor. In order to serve as force sensor the fiber optic grating should be aligned in best case 45 degrees to the direction of force. In case the fiber optic sensors are used as vibration sensor the diagnostic system 11 carries out a frequency analysis (in particular a fast Fourier transformation FFT) resulting in frequency pattern. The detected frequency pattern is then compared with a target frequency pattern or with a previously detected frequency pattern. Thus, further information on turnout/rolling stock can be made available.

[0033] In Fig. 1 one fiber optic sensor 5 is directly attached to the rod 2. A further fiber optical sensor 6 is directly attached to the housing 4 of the point machine 1. The further fiber optic sensor 7 may act as a vibration or acoustic sensor, since the housing to which the further fiber optic sensor 6 is attached does not move and thus no vibrations resulting from moving parts are produced and detected. Other functionalities of sensor 7 are also possible.

[0034] In Fig. 2 one fiber optic sensor 5 is mechanically integrated within an eyelet of a connection section 12, wherein the sensor fiber is attached to a bolt 13. The bolt 13 connects the actuating rod 2 to a point blade to be moved.

[0035] In Fig. 3 a fiber optic sensor 8 is attached, e.g. glued, to a console 14 of the point machine 1". The console 14 is a part of the point machine which serves as an adapter to fix the housing of the point machine to a railway structure (e.g. to a sleeper).

[0036] According to the invention a fiber optic sensor is directly attached to the point machine which results in omission of copper wires, trackside electronics as well as additional fixing devices which may get loose. By using fiber optic sensors electromagnetic interference with the point machine monitoring system can be avoided. No interferences into the electrical circuitry occur. Thus, no safety case has to be made. Any type of point machine (AC 3 phases, AC 1 phase, DC) can be used with the inventive directly attached fiber optical sensor. Therefore, with the inventive point machine accurate measurements can be made thereby considerably reducing disturbances during railway traffic.

List of references signs

[0037] 

1, 1', 1"

point machine

2

actuating rod

3

motor

4

housing

5

fiber optic sensor attached to the rod

6

fiber optic sensor attached to the housing

7

fiber optic sensor attached within the eyelet of the connection section

8

fiber optic sensor attached to the console

9

acquisition unit

10

fiber optic cables

11

diagnostic system

12

connection section with eyelet between rod and point blade

13

bolt

14

console

Cited references

[0038] 

[1] https://www.voestalpine.com/bwg/static/sites/c015/downloads/de/ produkte/Roadmaster de.pdf

[2] T. Böhm "Accuracy Improvement of Condition Diagnosis of Railway Switches via External Data Integration"; 6th European Workshop on Structural Health Monitoring - Poster 16

[3] http://www.hastema.com/wp-content/uploads/2014/09/mobiwaps de.pdf

[4] CN 103323157 A

Claims

1. Point machine (1, 1', 1") comprising:

• a housing (4) and an actuating assembly with a motor (3) arranged inside the housing;

• an actuating rod (2) driven by the motor (3) for moving at least one point blade of a point;

• a fiber optic sensor (5, 6, 7, 8), wherein the fiber optic sensor (5, 6, 7, 8) is directly attached to the point machine (1, 1', 1") for detection of a parameter which indicates the condition of the point machine (1, 1', 1").

2. Point machine (1, 1', 1") according to claim 1 characterized in that the fiber optic sensor (6, 8) is attached to a non-moving element of the point machine, in particular the housing (4) or a console (14) attached to the housing (4).

3. Point machine (1) according to claim 1 characterized in that the fiber optic sensor (5) is directly attached to the actuating rod, in particular by means of adhesive bonding.

4. Point machine (1') according to claim 1 characterized in that the actuating rod comprises a connection section (12) with an eyelet for connecting the actuating rod (2) to the point blade and that the fiber optic sensor (7) is arranged within the eyelet.

5. Point machine (1, 1', 1") according to any one of claims 1 through 4 characterized in that the fiber optic sensor (5, 6, 7, 8) is a strain gauge force sensor.

6. Point machine (1, 1', 1") according to any one of claims 1 through 4 characterized in that the fiber optic sensor (5, 6, 7, 8) is a vibration sensor.

7. Point machine (1, 1', 1") according to any one of the preceding claims characterized in that more than one fiber optic sensor (5, 6, 7, 8) is directly attached to the point machine.

8. Point machine monitoring system comprising:

• a point machine (1, 1', 1") according to any one of the preceding claims;

• a data acquisition unit (9) which is connected to the fiber optic sensor (5, 6, 7, 8) via a fiber optic cable (10);

• a diagnostic system (11) for processing data measured by means of the fiber optic sensor (5, 6, 7, 8); and

• means for transmitting of data from the data acquisition unit (9) to the diagnostic system (11).

9. Use of a fiber optic sensor (5, 6, 7, 8) for predictive maintenance of a point machine (1, 1', 1"), wherein the fiber optic sensor (5, 6, 7, 8) is directly attached to the point machine (1, 1', 1").

10. Method for predictive maintenance of a point machine (1, 1', 1"), wherein:

• data is detected by means of a fiber optic sensor (5, 6, 7, 8);

• the detected data is transferred to a data acquisition unit via a fiber optic cable (10);

• a diagnostic system (11) evaluates whether a maintenance operation is required or not.

11. Method according to claim 10 characterized in that a frequency analysis is carried out resulting in frequency pattern, wherein the detected frequency pattern is compared to a target frequency pattern or with a previously detected frequency pattern.

12. Method according to claim 11 characterized in that the frequency pattern is used to determine the direction of movement of a point blade.

Drawing