METHOD FOR APPLYING EXTENSOMETRIC SENSORS IN RAILWAY TRACKS

• US 20110313686A1
• Filed: 03/05/2010
• Published: 12/22/2011
• Est. Priority Date: 03/05/2009
• Status: Active Grant

• Current Assignee: Product Concept Development, Inc., Product & Process Dvelopment, S.L.
• Original Assignee: Product Concept Development, Inc.
• Inventors: Saracho Rotaeche, Luis Maria, Arostegui Camacho, Iker Unai
• Granted Patent: US 8,892,368 B2
• Time in Patent Office: Days
• US Class Current: 702/42
• CPC Class Codes: B61K 9/08 Measuring installations for surveying permanent way applications of measuring apparatus or devices for track building purposes E01B35/00; measuring techniques G01
• CPC Class Codes: B61L 23/044 Broken rails
• CPC Class Codes: B61L 23/045 Rail wear
• CPC Class Codes: B61L 23/047 Track or rail movements
• CPC Class Codes: E01B 35/00 Applications of measuring apparatus or devices for track-building purposes apparatus on locomotives or cars to indicate or record bad track sections B61K9/00; measuring angles, linear dimensions, or irregularities in general G01B, G01C
• CPC Class Codes: G01B 21/32 for measuring the deformation in a solid
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01L 1/22 using resistance strain gauges
• CPC Class Codes: G01L 1/2206 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 1/2225 the direction being perpendicular to the central axis
• CPC Class Codes: G01L 1/2237 the direction being perpendicular to the central axis
• CPC Class Codes: G01L 1/2287 constructional details of the strain gauges adjustable resistors H01C10/00

Abstract

The invention relates to a method for applying extensometric sensors in railway tracks, in combination with electronic equipment and a post-processing of the signals and data obtained to measure the stresses on railway tracks and the like, as well as to measure contact forces between the wheel of the vehicle or train and the actual rail on which it is travelling. According to the method, the following is performed: capturing micro-deformations in a known point of the track; analyzing these micro-deformations; identifying the element corresponding to the micro-deformation signal peaks coinciding with the passage of the train over one of the cross members of the track; analyzing the micro-deformation signal peaks previously identified; obtaining signals by means of sensors (5) arranged in plates (6) screwed to the rail (7); and finally calibrating each detected micro-deformation peak and the relationship thereof with the magnitudes to be measured.

Claims

1. A method for applying extensometric sensors in railway tracks using electronic analog/digital signal recording equipment and software algorithms to measure mechanical magnitudes in the wheel-rail contact in railways, comprising:

installing extensometric sensors in rails of railway tracks such that two aluminium plates are arranged by rail of track, one on each side of the rail and the shape of which is specifically designed so that the sensors arranged therein correctly measure without being contaminated by other events which could occur in the track, the micro-deformations in that point of the rail, having been provided that the extensometric sensors are arranged in fours in each plate, two of them in the upper part, one placed perpendicularly to the other, and the other two in the lower part of the plate one placed parallel to the other;

with the particularity that the two upper sensors, together with the other two counterparts of the plate placed symmetrically in the other part of the rail form a complete Wheatstone bridge, only sensitive to the tensions and compressions produced in that portion of the track and being able to provide a measurement of the vertical force or weight produced thereon;

whereas the two lower sensors together with the other two counterparts placed in the symmetry plate of the other side of the rail form another complete Wheatstone bridge only sensitive to the bending of the rail in that point, being able to measure the moment produced and therefore the lateral force which that portion of the rail is subjected to.

2. The method according to claim 1, wherein

each plate is optionally formed as a complete Wheatstone bridge such that by means of the algebraic summation of its signals the axial deformation is obtained, and the difference allows obtaining the bending deformation due to the moment.

3. The method according to claim 1,

the plate containing the extensometric measurement sensors is screwed to the web of the rail, being set therein by means of shims tailor made to the curvature of each type of rail such that the plate remains placed in vertical position, the preferred placement site of such plate being the part of the web of the rail which coincides with the center of the shaft of one or several cross members on which the track is set, such that the sensor captures all the reaction of the forces acting on that portion of the rail.

4. The method according to claim 1, wherein

the interconnection of the specific measurement plates with electronic recording equipment provided with the capacity for recording and converting recorded analog-digital signals, with or without capacity for storing thereof.

5. The method according to claim 3, wherein

the connection of the recording equipment to a computer, the latter being able to be connected or not connected to a LAN network, provided with a computer software made up of processing algorithms and calculation of the data acquired and transmitted by electronic equipment evaluating and calculating the magnitudes of stresses and wheel-rail contact forces from the measured signals, also being able to be from direct calculations, indirect calculations related with the direct magnitudes measured and the time, such as for example the front incidence angle of a train upon entering a bend and the speed of the train, among others.

6. The method according to claim 4, wherein

that different groups of plates of sensors are optionally placed on the same rail, separated a determined distance such that the algorithms and the analysis of the micro-deformations peaks in the different placement points of the plates of sensors and the time in which those peaks are produced, allow calculating indirect magnitudes as the speed and the acceleration of a train.

7. The method according to claim 1, wherein

two groups of plates of sensors are optionally placed, one in the web of the outer rail and another in the web of the inner rail of a bend of a track, radially in the same point with respect to the cross members and such that the post-processing algorithms will compare the phase shift time of the signal coming from the outer rail with respect to the inner rail and knowing the speed of the train to enable obtaining the front incidence angle of the train in that bend by means of the formulas:

e=v·

t, wherein e=space traveled, v=speed of the train or vehicle and t=time; and

[F]=arctan (e/d), wherein [F]=front incidence angle, e=space traveled and d=distance between inner and outer rail.

8. The method according to claim 1, wherein

the electronic equipment are calibrated based on using other known measurement systems and precision proven systems for an event in particular, such as for example applying a known force in the measurement point (above the cross member) and in each measurement direction (vertical and horizontal) by means of vehicles with known weight (vertical stresses) and load cells measuring forces applied with hydraulic jacks or the like (horizontal stresses) as well as by means of data obtained in a theoretical manner using calculation techniques and computer numerical simulation techniques.

9. The method according to claim 1, further comprising

including a computer support capable of calculating the magnitudes of stresses and forces of wheel-rail contact, formed by algorithms programmed for the instantaneous processing of the signals coming from the sensors through the recording equipment, calculating the direct and indirect magnitudes object of analysis, capable of detecting the times in which each measured signal peak is given, interpolating and resampling, converting the values of the recorded electric signals to engineering magnitudes of force, and returning the results in a legible form through a computer system.