DEVICE FOR DETECTING CROSSTIES OF A TRACK

Abstract

A device for detecting crossties of a track comprises a crosstie detection sensor (11), which is arranged on a track-laying machine, optionally on a track measuring wagon associated with the track-laying machine, for measuring and determining the position of crossties (5, 19) on the track. In order to ascertain the position of crossties, the crosstie detection sensor (11) comprises a magnet, which generates a magnetic field in a magnetic circuit with at least one air gap between the crosstie detection sensor (11) and the track, and a Hall sensor (13), which is arranged in the magnetic circuit and the Hall voltage (U) of which Hall sensor (13) is used to determine the position of the crossties (5, 19), said Hall voltage changing in the track longitudinal direction (A, s).

Description

FIELD OF THE INVENTION

The invention relates to a device for detecting crossties of a track comprising a crosstie detection sensor which is arranged on a track-laying machine, optionally on a track measuring wagon associated with the track-laying machine, for measuring and determining the position of crossties on the track.

DESCRIPTION OF THE PRIOR ART

Such crosstie detection sensors are used in particular to measure and determine the position of metallic fasteners that connect the rail to a crosstie, which also allows the position of the crosstie to be clearly determined.

Tamping machines are machines that correct the track position. For this purpose, measuring systems are used that measure the actual track height and the actual track alignment as well as the actual cant of the track during operation and compare them with specified target values. With the help of a track lifting and lining unit, the track grid is lifted and laterally aligned until the difference between the specified target position and the actual position is zero and fixed in this position by compacting the gravel under the crossties with the help of a tamping unit. The track grid is lifted and aligned using appropriate hydraulic lifting and lining cylinders with proportional or servo control. The tamping tools of such track-laying machines must plunge precisely into the space between the crossties in order to prevent destruction and damage to the crossties. Great attention must therefore be paid to the precise positioning of the tamping machine and its tools. Automatic positioning and advance of track-laying machines is possible in cases where the crossties are visible and not covered by a layer of gravel.

In addition to maintenance work, tamping machines are also used for tamping new track layers, after gravel cleaning work or track rebuilding. This work is characterized by multiple tamping passes. These tamping passes are characterized by the fact that the track is graveled up to the top of the rail and the tamping machine performs large lifts. The position of the crossties is only approximately visible to the operator during lifting due to the expressing unevenness of the gravel. The problem with this is that the tamping machine operator can only use feel and experience to advance the machine and position the tamping tools above the intermediate compartment. Automatic advance is practically impossible. If the positioning of the tamping tools is not correct, the crosstie will be hit and damaged. Another disadvantage is that the machine performance is severely impaired.

The position of the rails, crossties and rail fastenings can be recognized using various optical systems, for example laser scanners or video cameras. This also enables the tamping tools to be positioned automatically and accurately and the tamping machine to drive forwards automatically. However, the known optical methods fail when the tracks are graveled up to the top edge of the rails.

Another problem with tracks graveled up to the upper edge of the rail is that the machine operator does not recognize obstacles in the intermediate compartment, such as turnout drives, turnout rods and turnout locks, which often occur in turnouts, and damages them during the tamping process with the tamping units. Optical measuring methods do not help here either.

Conventional inductive and capacitive analogue sensors have a maximum detection distance of around 30 mm. However, there is a much greater distance between the upper edge of the rail and the height of the rail fasteners to be detected, which means that such sensors cannot be used in a meaningful way. The problem with guiding an inductive sensor, for example, is that it would have to be placed deep down and thus moved through the gravel. There is also the difficulty that the fasteners have different heights depending on the type, which is also problematic in view of the small measuring distances. In practice, there are many different rail fasteners. They are characterized by the screw connection and the fact that the fasteners are at least predominantly made of steel (ferromagnetic). These fasteners are located in the immediate vicinity of the rail, have a low ferromagnetic mass and are sometimes so far below the top edge of the rail that they cannot be reliably detected with known inductive or capacitive sensors. In principle, if they are lowered sufficiently close to the fasteners for measurement, they can detect the fasteners. However, if gravel is laid up to the top edge of the rail, such solutions are practically not possible.

SUMMARY OF THE INVENTION

The invention is therefore based on the task of finding a detection device and an arrangement which avoids the above-mentioned disadvantages and clearly detects the rail fastening means even in the case of full gravelling and being guided with a large distance (above the gravel) to the rail fastening means.

The invention solves the task set by the fact that the crosstie detection sensor comprises a magnet generating a magnetic field in a magnetic circuit with at least one air gap between the crosstie detection sensor and the track, and a Hall sensor arranged in the magnetic circuit, the Hall voltage of which Hall sensor changing in the longitudinal direction of the track serves to determine the position of the crossties in the track. Advantageous embodiments of the invention are shown in the dependent claims.

A magnetic field is generated in the magnetic circuit via an electromagnet and/or permanent magnet, which magnetic field is measured by means of a Hall sensor through which current flows and whose Hall voltage increases with the presence of a rail fastening because of the reduction of the magnetic resistance and this increase is used to determine the position of the rail fastenings and thus the crossties in the longitudinal direction of the track and to control the automatic advance of a track-laying machine. Essentially, the air gap and thus the magnetic resistance change depending on whether or not a rail fastening, or possibly other metallic obstacles such as turnout drives, are present, as is the case in particular between two crossties. The course of the Hall voltage over the length of the track, i.e. the respective position of the crosstie detection sensor in the track, is used to determine the position of the rail fastening and thus of the crossties in the longitudinal direction of the track.

The magnetic circuit closes between two crossties across the rail. If a rail fastening comes into this magnetic effective range, the magnetic resistance decreases and the magnetic field therefore increases. As the measurement of the rail fastening and thus the change in the magnetic field and the position of the crossties takes place a few crossties before the tamping units are positioned, the signal can be evaluated in advance and the center position can be determined.

The vectorial Lorentz force applies to a magnetic field:

$\overrightarrow{F_L}=Q·\left(\overrightarrow{v}\times \overrightarrow{B}\right)$

• • F_L . . . Lorentz force
  • Q . . . Charge
  • v . . . Velocity of the charge carriers
  • B . . . Magnetic field

A Hall effect sensor that is operated with a known current I measures the magnetic field component B_y that occurs orthogonally to its surface. An electric field E_x is generated. In proportion to this field the voltage U can be measured on the side surfaces. The crosstie detection sensor is mounted on a carrier wagon and is guided at a constant height above the rail and the rail fastenings. The distance travelled and the Hall voltage are measured continuously. The signal is analyzed. For this purpose, a limit value is determined progressively starting from the difference between the basic level and the peak value of the signal. The average value of the signal at this limit value gives the average position of the rail fastening and thus the position of the crosstie. The measured distances a_i from crosstie to crosstie are used for advance control and positioning of the tamping tools.

The advantage of this design according to the invention is the measurement through a layer of gravel and the precise positioning of the tamping tools that is possible as a result. This allows the tamping machine to be operated at high speed in automatic advance mode. The arrangement can also detect obstacles made of ferroelectric material, for example drive rods for turnouts in the intermediate compartment, from several crosstie detection sensors arranged next to each other on the wagon.

BRIEF DESCRIPTION OF THE INVENTION

The subject of the invention is shown schematically in the drawings, wherein

FIG. 1 shows a schematic cross-sectional view of a crosstie with rail and W-fastening,

FIG. 2 shows a schematic cross-sectional view of a crosstie with rail and K-fastening,

FIG. 3 schematically shows the structure of the threshold detection sensor with magnetic field,

FIG. 4 shows the basic structure of a Hall effect sensor,

FIG. 5 schematically shows the measurement sequence and the resulting voltage signal at the Hall sensor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a rail 1 in cross-section, which is screwed onto a crosstie 5 at an inclination of 1:40. The crosstie screw 2, the tension clamp 3, the angle guide plate 4 and the intermediate layer 6 are shown in view. The tension clamp 3, the crosstie 5 and the crosstie screw 2 are made of steel and thus influence a magnetic flux change when a crosstie detection sensor is moved along the rail 1. This allows their position in the longitudinal direction of the track or their longitudinal position in the track to be clearly detected.

FIG. 2 shows another type of rail fastening, the so-called K fastening (clamping plates). The rail 1 is screwed onto the crosstie 5 with an inclination of 1:40. The hook screw 7 with fastening nut, the clamping plate 8, the crosstie screw 9, the ribbed plate 10 and the elastic intermediate layer 6 are shown. Hook screw 7, ribbed plate 10 and clamping plate 8 are made of steel and reduce the magnetic resistance when a crosstie detection sensor passes over the K-fastening.

FIG. 3 schematically shows the measurement setup of a crosstie detection sensor 11 in question, which is arranged on a track-laying machine not shown in detail, possibly on a track measuring wagon associated with the track-laying machine, for measuring and determining the position of crossties 5, 19 in the track. The crosstie detection sensor 11 comprises an electromagnet 12, which generates a magnetic field in a magnetic circuit with at least one air gap between the crosstie detection sensor 11 and the track, and a Hall sensor 13 arranged in the magnetic circuit. The Hall sensor 13 is arranged in this air gap between the crosstie detection sensor 11 and the track. The Hall voltage U, which changes in the longitudinal direction of the track A, s, i.e. along the track, when the crosstie detection sensor 11 is moved, is used to determine the position of the crossties 5, 19 in the track.

The crosstie detection sensor 11 is equipped with an electromagnet 12. An electric coil of the electromagnet 12 and a magnetic core 11, in particular a soft iron core of the crosstie detection sensor 11, generate a magnetic field 14, 15, which is introduced into the rail head. The soft iron core of the crosstie detection sensor 11 is essentially U-shaped. The magnetic core 11 is guided at a small distance above the rail head in the longitudinal direction of the track or slides directly on the rail head with one leg of the soft iron core. It is also possible to introduce the magnetic field into the rail head via an impeller wheel. If there is no rail fastening, the magnetic circuit is closed at the other end of the magnetic core 11, i.e. via the other leg of the soft iron core directly to the rail head of rail 1. The end of the other leg of the magnetic core is guided approximately over any rail fastenings and, in the example, carries the Hall sensor 13 on its contact surface to the air gap. The Hall sensor 13 is thus arranged in the magnetic circuit.

In the area of a crosstie fastening, the magnetic field changes due to additional coupling of the magnetic field 14 via the rail fastening, in particular the crosstie screw 2 or the hook screw 7 towards the end of the magnetic core equipped with the Hall sensor 13. The magnetic resistance decreases, the magnetic field increases and the measured Hall voltage U rises. For reasons of better magnetizability, the magnetic core 11 can be formed from laminations, in particular from several layers of mutually insulated transformer sheets.

FIG. 4 schematically shows the Hall effect sensor 16 through which the magnetic field B_y flows. A current I flows through the Hall effect sensor, which current I can be tapped across the Hall effect sensor via contacts and generates an electrical voltage U proportional to the magnetic field B_y. The following applies to the Hall voltage that occurs:

$U=R_H·\frac{I·B_Y}{d}$

As the relation shows, the resulting voltage U is directly proportional to the current I, a material-specific Hall constant R_H and the magnetic field B_Y. As the thickness d of the Hall layer increases, the voltage U decreases.

FIG. 5 schematically shows the mode of operation. The crosstie detection sensor 11 is guided in direction A along the rail 18 at a constant height. The rail 18 is connected via fastening means 17 to crossties 19 at a distance of a_i between the crossties. The course of the measured Hall voltage U over the track length s is shown above. If there are no fasteners 17, a voltage level 22 is measured. The Hall voltage U increases (21) in the area of the metal rail fasteners 17. The position of the fasteners 17 and with them the crossties 19 can now be determined. A limit value 20 between the two values is continuously determined from the difference between the voltage peaks 21 and the base level 22. The average value of the intersection points of the voltage peak 21 with this limit value 20 gives the position of the fastening means 17 and thus the position of the crosstie 19.

Claims

1. A device for detecting crossties of a track, said device comprising: a crosstie detection sensor that is arranged on a track-laying machine or on a track measuring wagon associated with the track-laying machine, said crosstie detection sensor measuring and determining positions of the crossties on the track;wherein the crosstie detection sensor comprisesa magnet generating a magnetic field in a magnetic circuit with at least one air gap between the crosstie detection sensor and the track; anda Hall sensor producing a Hall voltage arranged in the magnetic circuit;wherein the Hall voltage of said Hall sensor changing in a longitudinal direction of the track provides a determination of the positions of the crossties in the track.

2. The device according to claim 1, wherein the magnet includes an electromagnet or a permanent magnet.

3. The device according to claim 2, wherein the magnet includes a permanent magnet, and a current coil of the electromagnet is connected to a direct current source and generates a direct magnetic field in the magnetic circuit.

4. The device according to claim 2, wherein the magnet includes a permanent magnet, and a current coil of the electromagnet is connected to an alternating current source and generates an alternating magnetic field in the magnetic circuit.

5. The device according to claim 1, wherein detection of metallic components between the crossties is provided by the crosstie detection sensor and one or more additional crosstie detection sensors arranged next to each other in a transverse direction of the track.

6. The device according to claim 5, wherein at least one of the crosstie detection sensors is supported so as to be displaced in the transverse direction of the track by a displacement device associated with the track-laying machine and/or the track measuring wagon so as to search for metallic components on the track.

7. The device according to claim 6, wherein the at least one crosstie detection sensor is arranged on the track-laying machine and/or the track measuring wagon so as to be adjustable in height with respect to the track.

8. The device according to claim 1, wherein the Hall sensor is positioned in the air gap.

9. The device according to claim 1, and further comprising a control system that continuously determines a limit value from a difference of voltage peaks of the Hall voltage over a track length and a base level of the Hall voltage, the limit value lying between the voltage peaks and the base level, and determines the position of the crosstie in the track from an average value of intersection points of each of the voltage peaks with the limit value.

10. The device according to claim 2, wherein detection of metallic components between the crossties is provided by the crosstie detection sensor and one or more additional crosstie detection sensors arranged next to each other in a transverse direction of the track.

11. The device according to claim 10, wherein at least one of the crosstie detection sensors is supported so as to be displaced in the transverse direction of the track by a displacement device associated with the track-laying machine and/or the track measuring wagon so as to search for metallic components on the track.

12. The device according to claim 11, wherein the at least one crosstie detection sensor is arranged on the track-laying machine and/or the track measuring wagon so as to be adjustable in height with respect to the track.

13. The device according to claim 3, wherein detection of metallic components between the crossties is provided by the crosstie detection sensor and one or more additional crosstie detection sensors arranged next to each other in a transverse direction of the track.

14. The device according to claim 13, wherein at least one of the crosstie detection sensors is supported so as to be displaced in the transverse direction of the track by a displacement device associated with the track-laying machine and/or the track measuring wagon so as to search for metallic components on the track.

15. The device according to claim 14, wherein the at least one crosstie detection sensor is arranged on the track-laying machine and/or the track measuring wagon so as to be adjustable in height with respect to the track.

16. The device according to claim 4, wherein detection of metallic components between the crossties is provided by the crosstie detection sensor and one or more additional crosstie detection sensors arranged next to each other in a transverse direction of the track.

17. The device according to claim 16, wherein at least one of the crosstie detection sensors is supported so as to be displaced in the transverse direction of the track by a displacement device associated with the track-laying machine and/or the track measuring wagon so as to search for metallic components on the track.

18. The device according to claim 17, wherein the at least one crosstie detection sensor is arranged on the track-laying machine and/or the track measuring wagon so as to be adjustable in height with respect to the track.

19. The device according to claim 3, and further comprising a control system that continuously determines a limit value from a difference of voltage peaks of the Hall voltage over a track length and a base level of the Hall voltage, the limit value lying between the voltage peaks and the base level, and determines the position of the crosstie in the track from an average value of intersection points of each of the voltage peaks with the limit value.

20. The device according to claim 4, and further comprising a control system that continuously determines a limit value from a difference of voltage peaks of the Hall voltage over a track length and a base level of the Hall voltage, the limit value lying between the voltage peaks and the base level, and determines the position of the crosstie in the track from an average value of intersection points of each of the voltage peaks with the limit value.