METHOD FOR CONTROLLING WHEEL DEFORMATION AND ASSOCIATED DEVICE AND SYSTEM

Abstract

A method for controlling the deformation of a wheel includes obtaining, for multiple predefined angular positions on the wheel, a parameter characterizing an angular velocity of the wheel when the wheel is in contact with the running surface at each predefined angular position while the wheel is rolling on a running surface, and calculating a radius value of the wheel for each predefined angular position using the parameter characterizing the angular velocity obtained for that angular position.

Claims

1. A method of controlling deformation of a wheel, the method comprising: while the wheel is rolling on a running surface, obtaining a parameter, for multiple predefined angular positions on the wheel, characterizing an angular velocity of the wheel when the wheel is in contact with the running surface at said predefined angular position; and calculating a radius value of the wheel for each predefined angular position using the parameter characterizing the angular velocity obtained for said angular position.

2. The method of controlling deformation of a wheel according to claim 1, wherein the parameter characterizing the angular velocity of the wheel is measured by a sensor, with the sensor comprising a gearwheel and a sensing element configured to detect an edge of each tooth of the gearwheel.

3. The method for controlling the deformation of a wheel according to claim 2, wherein the parameter characterizing the angular velocity of the wheel is a direct time difference for the predefined angular position, the direct time difference being the time difference between the detection of the edge of two teeth of the gearwheel, the two teeth preferably being two consecutive teeth of the gearwheel.

4. The method for controlling the deformation of a gear according to claim 3, wherein the calculation of a radius value of the gear for each predefined angular position uses a filtered time difference, wherein the filtered time difference is a weighted average of direct time differences for multiple predefined angular positions.

5. The method for controlling the deformation of a wheel according to claim 4, wherein the filtered time difference is calculated by weighting the direct time differences for multiple predefined angular positions by a Hann window.

6. The method of controlling deformation of a wheel according to claim 4, wherein the calculation of a wheel radius value for each predefined angular position is the product of a predetermined wheel radius and the ratio between the direct time difference and the filtered time difference obtained for said predefined angular position.

7. The method of controlling deformation of a wheel according to claim 1, with the method comprising calculating at least four wheel radius values for each predefined angular position, a consolidated wheel radius value for each predefined angular position being calculated using at least four wheel radius values calculated for each predefined angular position.

8. A device for controlling the deformation of a wheel, the device being arranged to be connected to a sensor configured to obtain, while the wheel is rolling on a running surface, for multiple predefined angular positions on the wheel, a parameter characterizing an angular speed of the wheel when the wheel is in contact with the running surface at said predefined angular position, the device comprising a calculation module of a radius value of the wheel for each predefined angular position using the parameter characterizing the angular speed obtained for said angular position.

9. A wheel deformation controlling system, in particular for use on board a rail vehicle, the wheel deformation controlling system comprising a sensor and a wheel deformation controlling device connected to the sensor, wherein the wheel deformation controlling device is according to claim 8.

10. A vehicle, in particular a railway vehicle, comprising at least one wheel and a wheel deformation controlling system according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features and advantages of the invention will become clearer when reading the following description, given only as a non-exhaustive example with reference to the attached drawings, in which:

[0020] FIG. 1 is a schematic representation of a railway vehicle equipped with a wheel deformation controlling system comprising a sensor and a wheel deformation controlling device according to the invention;

[0021] FIG. 2 is a schematic representation of a wheel equipped with a wheel deformation controlling system comprising a sensor and a wheel deformation controlling device according to the invention;

[0022] FIG. 3 is a schematic representation of the time evolution of the signal generated by the sensor;

[0023] FIG. 4 is an example of a weighting window used in the wheel deformation controlling method;

[0024] FIG. 5 is an example of the evolution of a signal generated by the sensor representing the measurement of time between two successive teeth of a sensor gearwheel shown in FIG. 2, as a function of a measurement sample number;

[0025] FIG. 6 is an example of the evolution of a signal generated by the sensor as a function of the signal generated in FIG. 5, representing the value of the wheel radius as a function of the sample number; and

[0026] FIG. 7 is a schematic representation of the wheel deformation obtained from the signal generated in FIG. 6.

DETAILED DESCRIPTION

[0027] In the following description, a direct orthonormal base (X, Y, Z) is considered. The elevation direction, Z, is defined according to the height of the vehicle and corresponds, for example, to the vertical direction when the vehicle is on a horizontal track. The longitudinal direction, X, corresponds to the forward/rearward direction of the vehicle and the transverse direction, Y, corresponds to the width of the vehicle.

[0028] The terms “upper” and “lower” as well as “high” and “low” are defined in relation to the elevation direction, Z. The terms “left” and “right” are defined in relation to the transverse direction, Y, in the normal direction of travel of the vehicle.

[0029] The wheel deflection controlling system 10, shown schematically in FIG. 1, is intended for use on a rail vehicle 1 and is designed to evaluate the radius of a wheel 4 in multiple angular positions.

[0030] Railway vehicle 1 is a locomotive, wagon or railcar, for example.

[0031] Railway vehicle 1 comprises an axle 6, where axle 6 comprises the wheel, 4, and a shaft, 7 (FIG. 2). Wheel 4 is rotatable around a Y-Y axis of shaft 7.

[0032] When rail vehicle 1 is running on a track, wheel 4 is supported and runs on a running surface 8.

[0033] The wheel deformation controlling system 10 comprises a wheel deformation controlling device 12 and a sensor 14 for measuring a parameter characterizing the angular velocity of wheel 4 (FIG. 1).

[0034] As shown in FIG. 2, the wheel has a rim 16 and a tread 18. The rim 16 connects shaft 7 to the tread 18. Tread 18 is intended to rest and run on the running surface 8 at a contact point 19.

[0035] Wheel 4 has multiple predefined angular positions. In particular, the wheel consists of n predefined angular positions θ.sub.i with i between 1 and n. A wheel radius Ri is associated with each angular position θ.sub.i.

[0036] Sensor 14 comprises a gearwheel 20 and a sensing element 22. The sensor 14 is an antiskid system component, for example.

[0037] Gearwheel 20 is rotatable around the Y-Y axis of shaft 7. Gearwheel 20 is rotationally fixed to wheel 4. The gearwheel 20 comprises multiple teeth 24, evenly spaced circumferentially around the Y-Y′ axis. In particular, gearwheel 20 has a number of teeth 24 greater than or equal to the number n of predefined angular positions. In a particular embodiment described here, the gearwheel has a number of teeth 24 equal to the number n of predefined angular positions. Each tooth 24 consists of a front face 26, a rear face 28 and a head 30 connecting the front face 26 to the rear face 28.

[0038] The sensing element 22 is suitable for detecting the passage of teeth 24 of the gearwheel 20 when the gearwheel 4 rotates. For example, the sensing element 22 is positioned opposite the toothed edge of the gearwheel.

[0039] The sensing element 22 detects the passage of the teeth magnetically. In an alternative embodiment, the sensing element 22 detects the passage of the teeth optically.

[0040] The sensing element 22 is suitable for detecting the tooth edge 24 of the gearwheel. In particular, sensing element 22 is suitable for detecting the leading edge 26 and/or trailing edge 28 of the gear teeth 24. In the embodiment shown here, the sensing element 22 is adapted to detect the leading edge 26 of the teeth 24.

[0041] For example, the sensing element generates a signal s over time, as shown in FIG. 3.

[0042] Sensing element 22 of sensor 14 is configured to obtain, while wheel 4 is rolling on the running surface 8, and for each angular position θ.sub.i, a parameter characterizing the angular velocity of wheel 4 when the wheel is in contact with the running surface through said predefined angular position. More particularly, sensing element 22 of sensor 14 is angularly offset from the portion 19 of the wheel in contact with the ground by an angle A. The angular velocity measured for the leading edge of the tooth located at θ.sub.i—A thus characterises the angular velocity of the wheel when it is in contact with the running surface by the position θi, as shown in FIG. 2.

[0043] In particular, sensing element 22 is configured to obtain a direct time difference ΔT.sub.i for each angular position θ.sub.i. The parameter characterizing the angular velocity of the wheel 4 for an angular position θ.sub.i is then the direct time difference ΔT.sub.i.

[0044] The direct time difference ΔT.sub.i is the time difference between the detection of the leading edge 26 of two teeth 24 of the gearwheel. The direct time difference ΔT.sub.i in the embodiment shown is the time difference between the detection of the leading edge of two consecutive teeth of the gearwheel, in particular the time difference between the detection of the leading edge 26 of two consecutive teeth of the gearwheel. The direct time difference ΔT.sub.i is then the time difference between the detection of the tooth edge located at the angular position θ.sub.i—A and the detection of the immediately preceding tooth edge. If there are as many teeth 24 as there are positions θ.sub.i, this direct time difference ΔT.sub.i thus corresponds to the time difference between the transition from the angular position θ.sub.i to the contact point 19 and the transition from the angular position θ.sub.i−1 to the contact point.

[0045] An example of the measurement of the time between two successive teeth 24 by the sensing element 22 is shown in FIG. 5, which represents the time between two successive teeth 24 as a function of a measurement sample number (each measurement sample is associated with an angular position θ.sub.i). In FIG. 5, a first curve C1 represents the measurement of the direct time difference ΔT.sub.i between two successive teeth 24 and a second curve C2 represents a filtered time difference ΔT.sub.filti, the calculation of which is described below, for a train travelling at 40 km/h with slight acceleration, a wheel with a nominal diameter of 1 metre and a number of gear teeth 24 equal to 80.

[0046] The deformation controlling device for wheel 10 includes a calculation module 32.

[0047] The calculation module 32 is configured to calculate the value of the wheel radius R.sub.i for each predefined angular position θ.sub.i using the parameter characterizing the angular velocity obtained for the predefined angular position. In particular, the calculation module is configured to calculate the value of the wheel radius R.sub.i for the position θi using the direct time difference ΔT.sub.i associated with the angular position θ.sub.i.

[0048] The calculation module 32 is further configured to calculate the value of the wheel radius R.sub.i for the predefined angular position θ.sub.i using the filtered time difference ΔT.sub.filti shown in FIG. 5, associated with the predefined angular position θ.sub.i. The filtered time difference ΔT.sub.filti associated with the predefined angular position θ.sub.i corresponds to a weighted average of direct time differences ΔT.sub.i for multiple predefined angular positions θi.

[0049] The calculation module 32 is configured, for example, to calculate the filtered time difference ΔT.sub.filti by weighting the direct time differences ΔTi for multiple predefined angular positions by a Hann window. Such a weighting window can be seen, for example, in FIG. 4, where p is a weighting coefficient. In particular, the calculation module 32 is configured to perform a weighted average of the k direct time differences whose angular position precedes the predefined angular position θ.sub.i and of the k direct time differences whose angular position follows the predefined angular position, with k a natural number less than half of n. In other words, the filtered time difference ΔT.sub.filti for a predefined angular position θ.sub.i is calculated using the direct time differences ΔT.sub.i for angular positions between ΔT.sub.i−k and θ.sub.i+k. In particular, and in the preferred embodiment, k is the natural number closest to one eighth of the number of teeth n. The filtered time difference ΔT.sub.filti is thus calculated using the direct time differences ΔT.sub.i associated with the angular positions θi included on the quarter gearwheel surrounding the predefined angular position θ.sub.i.

[0050] Alternatively, a rectangular window or a Hamming window or a Blackman window can be used instead of the Hann window.

[0051] The calculation module 32 is configured to calculate the value of wheel radius R.sub.i of wheel 4 for each predefined angular position as the product of a predetermined wheel radius, for example an average wheel radius R.sub.m, and the ratio between the direct time difference ΔT.sub.i and the filtered time difference ΔT.sub.filti obtained for said predefined angular position θ.sub.i. The calculation module is configured to calculate the R.sub.i value of wheel 4 for each predefined angular position with the following equation.

[00001]$\begin{array}{cc}{R}_i=R_m.Math.\frac{\Delta .Math.T_i}{\Delta .Math.T_{\mathrm{filti}}}& \left[\mathrm{Math}..Math.1\right]\end{array}$

[0052] An example of the value of the estimated radius for the direct time difference and the filtered time difference for the case of the curves shown in FIG. 5 for a train running at 40 km/h with slight acceleration, a wheel with a nominal diameter of 1 meter and a number of gear teeth 24 equal to 80 is given by the graph shown in FIG. 6, showing the value of the estimated radius as a function of the sample number.

[0053] FIG. 7 shows the wheel deformation obtained from the graph in FIG. 6, with multiple wheel revolutions superimposed, to eliminate measurement noise. In this example, a facet type wheel deformation is observed.

[0054] A method for controlling the deformation of a wheel according to the invention will now be presented. The previously described wheel deformation controlling system 10 is specially adapted to implement the method now presented. The method now presented is further specially adapted to be implemented by the previously described wheel deformation controlling system 10.

[0055] The method includes a step of obtaining the parameter characterizing the angular velocity of the wheel for the plurality of predefined angular positions θ.sub.i followed by a step of calculating a value of radius Ri of wheel 4 for each predefined angular position θ.sub.i.

[0056] The obtaining step comprises obtaining, for the multiple predefined angular positions θ.sub.i on the wheel, while wheel 4 is rolling on the running surface 8, a parameter characterizing an angular velocity of the wheel, when wheel 4 is in contact with the running surface 8 through said predefined angular position θ.sub.i.

[0057] The obtaining step is implemented in particular when the rail vehicle is running at a substantially constant speed on running surface 8. The obtaining step is preferably carried out when wheel 4 is running on running surface 8 without slipping.

[0058] The obtaining step includes the measurement by the sensor 14 of the parameter characterizing the angular speed of wheel 4.

[0059] During the obtaining step, sensor 14 successively measures the direct time difference ΔT.sub.i for each predefined angular position θ.sub.i. The direct time difference ΔT.sub.i is measured in particular when a predefined angular position Oi is in contact with the running surface 8, or in other words when the sensing element 22 detects the leading edge 26 of a tooth 24 at a position θ.sub.i—A angularly offset from the position θi by angle A. The time difference ΔT.sub.i is then the time between the detection of the leading edge 26 of tooth 24 at the position θ.sub.i—A and the detection of the leading edge 26 of the preceding tooth 24.

[0060] After obtaining the direct time difference values ΔT.sub.i, a radius value R.sub.i for each angular position θ.sub.i is calculated in the calculation step. The calculation step is carried out in particular by calculation module 32.

[0061] The calculation of each wheel radius R.sub.i uses the direct time difference ΔT.sub.i obtained for each angular position θ.sub.i. The calculation of each wheel radius R.sub.i for the predefined angular position θ.sub.i also uses the filtered time difference ΔT.sub.filti, where the filtered time difference is a weighted average of direct time differences ΔT.sub.i for multiple predefined angular positions θ.sub.i. In particular, the filtered time difference ΔT.sub.filti is calculated as a weighted average of the direct time differences ΔT.sub.i for multiple predefined angular positions through a Hann window.

[0062] According to a particular embodiment, the obtaining step may extend over several wheel revolutions, for example. The obtaining step extends advantageously over at least 4 turns of the wheels. For each wheel revolution, a direct time difference ΔT.sub.i is obtained for a predefined angular position θ.sub.i. The direct time difference ΔT.sub.i for one wheel revolution is used to calculate a filtered time difference ΔT.sub.filti for one wheel revolution and a wheel radius R.sub.i for one wheel revolution for a predefined angular position θ.sub.i.

[0063] The wheel deformation controlling method thus includes the calculation of at least four wheel radius values R.sub.i for each predefined angular position θ.sub.i, in the calculation step The calculation step includes calculating a consolidated wheel radius value R.sub.ic for each predefined angular position, with the consolidated wheel radius value R.sub.ic for each predefined angular position θ.sub.i being calculated using the at least four wheel radius values R.sub.i calculated for each predefined angular position θ.sub.i.

[0064] The wheel deformation controlling method according to the invention not only makes it possible to determine wheel deformations, but also to quantify these deformations and to evaluate the actual shape of the wheel. In particular, it makes it possible to determine the proper wheel radius R.sub.i for each predefined angular position θ.sub.i.

[0065] The use of a sensor 14 comprising a gearwheel 20 and a sensing element 22 is particularly advantageous since it allows economical controlling of wheel deformations, since the sensor 14 is, for example, a component of a rail vehicle anti-lock brake system.

[0066] The calculation of the radius value using the filtered time difference ΔT.sub.filti and in particular the use of a Hann window improves the accuracy of the calculation of wheel deformation 4.

[0067] The calculation of a consolidated wheel radius R.sub.ic also improves the accuracy of the wheel deformation calculation by excluding potential anomalies during measurement.