Patent Publication Number: US-2021179152-A1

Title: Method for controlling wheel deformation and associated device and system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. non-provisional application claiming the benefit of French Application No. 19 14413, filed on Dec. 13, 2019, which is incorporated herein by reference in its entirety. 
     FIELD 
     The invention relates to controlling wheel deformation. 
     BACKGROUND 
     Document EP 1 559 625 presents a method for controlling the deformation of a wheel of a railway vehicle, comprising a step of obtaining the variation of the duty cycle of a gearwheel during its rotation, with the data making it possible to obtain these variations being measured by a sensor to which a wheel deformation controlling device is connected. The cyclic ratio is the time ratio during which the sensor is in front of the head of a gearwheel tooth to the time during which the sensor is in front of the head of the gearwheel tooth plus the time during which the sensor is in front of the groove preceding or following that gearwheel. The time variations in the duty cycle enable the relative deformations of the controlled wheel to be determined. 
     However, such a deformation controlling method only enables the relative deformation of the wheel being controlled to be determined and only provides partial knowledge of the condition of the wheel, which is not entirely satisfactory for ensuring the safety of the rail vehicle operations. 
     SUMMARY 
     To this end, the invention relates to a method for controlling the deformation of a wheel, with the method comprising the following steps:
         while the wheel is rolling on a running surface, obtaining, for multiple predefined angular positions on the wheel, a parameter characterizing a wheel angular velocity when the wheel is in contact with the running surface at said predefined angular position; and   calculation of a wheel radius value for each predefined angular position by using the parameter characterizing the angular velocity obtained for said angular position.       

     Thus, the wheel deformation controlling method not only makes it possible to determine the deformations of a wheel, but also to quantify these deformations and to evaluate the actual shape of the wheel. 
     Depending on other advantageous aspects of the invention, the wheel deformation controlling method includes one or more of the following features, taken alone or in any technically possible combination:
         the parameter characterizing the angular speed of the wheel is measured by a sensor, with the sensor comprising a gearwheel and a sensing element configured to detect one edge of each tooth of the gearwheel;   the parameter characterizing the angular velocity of the gear is a direct time difference for the predefined angular position, with the direct time difference being the time difference between the detection of the edge of two gearwheel teeth, with the two teeth preferably being two consecutive teeth of the gearwheel;   the calculation of a wheel radius value for each predefined angular position uses a filtered time difference, with the filtered time difference being a weighted average of direct time differences for multiple predefined angular positions;   the filtered time difference is calculated by weighting the direct time differences for multiple predefined angular positions by a Hann window;   the calculation of a wheel radius value for each predefined angular position is the product of an average wheel radius and the ratio between the direct time difference and the filtered time difference obtained for said predefined angular position;   the method comprises calculating at least four wheel radius values for each predefined angular position, wherein a consolidated wheel radius value for each predefined angular position is calculated using at least four wheel radius values calculated for each predefined angular position.       

     The invention also relates to a device for controlling a wheel deformation, with the device being adapted 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 velocity of the wheel when the wheel is in contact with the running surface at said predefined angular position, with the device comprising a module for calculating a wheel radius value for each predefined angular position using the parameter characterizing the angular velocity obtained for said angular position. 
     The invention furthermore relates to a wheel deformation controlling system, in particular intended to be fitted on-board a railway vehicle, with the wheel deformation controlling system comprising a sensor and a wheel deformation controlling device connected to the sensor, with the wheel deformation controlling device being a device as mentioned above. 
     The invention also relates to a vehicle, in particular a railway vehicle, comprising at least one wheel and a wheel deformation controlling system as mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         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; 
         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; 
         FIG. 3  is a schematic representation of the time evolution of the signal generated by the sensor; 
         FIG. 4  is an example of a weighting window used in the wheel deformation controlling method; 
         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; 
         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 
         FIG. 7  is a schematic representation of the wheel deformation obtained from the signal generated in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     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. 
     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. 
     Railway vehicle  1  is a locomotive, wagon or railcar, for example. 
     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 . 
     When rail vehicle  1  is running on a track, wheel  4  is supported and runs on a running surface  8 . 
     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 ). 
     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 . 
     Wheel  4  has multiple predefined angular positions. In particular, the wheel consists of n predefined angular positions θ i  with i between 1 and n. A wheel radius Ri is associated with each angular position θ i . 
     Sensor  14  comprises a gearwheel  20  and a sensing element  22 . The sensor  14  is an antiskid system component, for example. 
     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 . 
     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. 
     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. 
     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 . 
     For example, the sensing element generates a signal s over time, as shown in  FIG. 3 . 
     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 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 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 . 
     In particular, sensing element  22  is configured to obtain a direct time difference ΔT i  for each angular position θ i . The parameter characterizing the angular velocity of the wheel  4  for an angular position θ i  is then the direct time difference ΔT i . 
     The direct time difference ΔT 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 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 i  is then the time difference between the detection of the tooth edge located at the angular position θ i —A and the detection of the immediately preceding tooth edge. If there are as many teeth  24  as there are positions θ i , this direct time difference ΔT i  thus corresponds to the time difference between the transition from the angular position θ i  to the contact point  19  and the transition from the angular position θ i −1 to the contact point. 
     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 i ). In  FIG. 5 , a first curve C 1  represents the measurement of the direct time difference ΔT i  between two successive teeth  24  and a second curve C 2  represents a filtered time difference ΔT 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. 
     The deformation controlling device for wheel  10  includes a calculation module  32 . 
     The calculation module  32  is configured to calculate the value of the wheel radius R i  for each predefined angular position θ 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 i  for the position θi using the direct time difference ΔT i  associated with the angular position θ i . 
     The calculation module  32  is further configured to calculate the value of the wheel radius R i  for the predefined angular position θ i  using the filtered time difference ΔT filti  shown in  FIG. 5 , associated with the predefined angular position θ i . The filtered time difference ΔT filti  associated with the predefined angular position θ i  corresponds to a weighted average of direct time differences ΔT i  for multiple predefined angular positions θi. 
     The calculation module  32  is configured, for example, to calculate the filtered time difference ΔT 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 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 filti  for a predefined angular position θ i  is calculated using the direct time differences ΔT i  for angular positions between ΔT i −k and θ 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 filti  is thus calculated using the direct time differences ΔT i  associated with the angular positions θi included on the quarter gearwheel surrounding the predefined angular position θ i . 
     Alternatively, a rectangular window or a Hamming window or a Blackman window can be used instead of the Hann window. 
     The calculation module  32  is configured to calculate the value of wheel radius R i  of wheel  4  for each predefined angular position as the product of a predetermined wheel radius, for example an average wheel radius R m , and the ratio between the direct time difference ΔT i  and the filtered time difference ΔT filti  obtained for said predefined angular position θ i . The calculation module is configured to calculate the R i  value of wheel  4  for each predefined angular position with the following equation. 
     
       
         
           
             
               
                 
                   
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     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. 
       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. 
     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 . 
     The method includes a step of obtaining the parameter characterizing the angular velocity of the wheel for the plurality of predefined angular positions θ i  followed by a step of calculating a value of radius Ri of wheel  4  for each predefined angular position θ i . 
     The obtaining step comprises obtaining, for the multiple predefined angular positions θ 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 i . 
     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. 
     The obtaining step includes the measurement by the sensor  14  of the parameter characterizing the angular speed of wheel  4 . 
     During the obtaining step, sensor  14  successively measures the direct time difference ΔT i  for each predefined angular position θ i . The direct time difference ΔT 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 i —A angularly offset from the position θi by angle A. The time difference ΔT i  is then the time between the detection of the leading edge  26  of tooth  24  at the position θ i —A and the detection of the leading edge  26  of the preceding tooth  24 . 
     After obtaining the direct time difference values ΔT i , a radius value R i  for each angular position θ i  is calculated in the calculation step. The calculation step is carried out in particular by calculation module  32 . 
     The calculation of each wheel radius R i  uses the direct time difference ΔT i  obtained for each angular position θ i . The calculation of each wheel radius R i  for the predefined angular position θ i  also uses the filtered time difference ΔT filti , where the filtered time difference is a weighted average of direct time differences ΔT i  for multiple predefined angular positions θ i . In particular, the filtered time difference ΔT filti  is calculated as a weighted average of the direct time differences ΔT i  for multiple predefined angular positions through a Hann window. 
     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 i  is obtained for a predefined angular position θ i . The direct time difference ΔT i  for one wheel revolution is used to calculate a filtered time difference ΔT filti  for one wheel revolution and a wheel radius R i  for one wheel revolution for a predefined angular position θ i . 
     The wheel deformation controlling method thus includes the calculation of at least four wheel radius values R i  for each predefined angular position θ i , in the calculation step The calculation step includes calculating a consolidated wheel radius value R ic  for each predefined angular position, with the consolidated wheel radius value R ic  for each predefined angular position θ i  being calculated using the at least four wheel radius values R i  calculated for each predefined angular position θ i . 
     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 i  for each predefined angular position θ i . 
     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. 
     The calculation of the radius value using the filtered time difference ΔT filti  and in particular the use of a Hann window improves the accuracy of the calculation of wheel deformation  4 . 
     The calculation of a consolidated wheel radius R ic  also improves the accuracy of the wheel deformation calculation by excluding potential anomalies during measurement.