Method for controlling wheel deformation and associated device and system

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.

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; andcalculation 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.

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 system10, shown schematically inFIG.1, is intended for use on a rail vehicle1and is designed to evaluate the radius of a wheel4in multiple angular positions.

Railway vehicle1is a locomotive, wagon or railcar, for example.

Railway vehicle1comprises an axle6, where axle6comprises the wheel,4, and a shaft,7(FIG.2). Wheel4is rotatable around a Y-Y axis of shaft7.

When rail vehicle1is running on a track, wheel4is supported and runs on a running surface8.

The wheel deformation controlling system10comprises a wheel deformation controlling device12and a sensor14for measuring a parameter characterizing the angular velocity of wheel4(FIG.1).

As shown inFIG.2, the wheel has a rim16and a tread18. The rim16connects shaft7to the tread18. Tread18is intended to rest and run on the running surface8at a contact point19.

Wheel4has multiple predefined angular positions. In particular, the wheel consists of n predefined angular positions θiwith i between 1 and n. A wheel radius Ri is associated with each angular position θi.

Sensor14comprises a gearwheel20and a sensing element22. The sensor14is an antiskid system component, for example.

Gearwheel20is rotatable around the Y-Y axis of shaft7. Gearwheel20is rotationally fixed to wheel4. The gearwheel20comprises multiple teeth24, evenly spaced circumferentially around the Y-Y′ axis. In particular, gearwheel20has a number of teeth24greater than or equal to the number n of predefined angular positions. In a particular embodiment described here, the gearwheel has a number of teeth24equal to the number n of predefined angular positions. Each tooth24consists of a front face26, a rear face28and a head30connecting the front face26to the rear face28.

The sensing element22is suitable for detecting the passage of teeth24of the gearwheel20when the gearwheel4rotates. For example, the sensing element22is positioned opposite the toothed edge of the gearwheel.

The sensing element22detects the passage of the teeth magnetically. In an alternative embodiment, the sensing element22detects the passage of the teeth optically.

The sensing element22is suitable for detecting the tooth edge24of the gearwheel. In particular, sensing element22is suitable for detecting the leading edge26and/or trailing edge28of the gear teeth24. In the embodiment shown here, the sensing element22is adapted to detect the leading edge26of the teeth24.

For example, the sensing element generates a signal s over time, as shown inFIG.3.

Sensing element22of sensor14is configured to obtain, while wheel4is rolling on the running surface8, and for each angular position θi, a parameter characterizing the angular velocity of wheel4when the wheel is in contact with the running surface through said predefined angular position. More particularly, sensing element22of sensor14is angularly offset from the portion19of the wheel in contact with the ground by an angle A. The angular velocity measured for the leading edge of the tooth located at θi-A thus characterises the angular velocity of the wheel when it is in contact with the running surface by the position θi, as shown inFIG.2.

In particular, sensing element22is configured to obtain a direct time difference ΔTifor each angular position θi. The parameter characterizing the angular velocity of the wheel4for an angular position θiis then the direct time difference ΔTi.

The direct time difference ΔTiis the time difference between the detection of the leading edge26of two teeth24of the gearwheel. The direct time difference ΔTiin 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 edge26of two consecutive teeth of the gearwheel. The direct time difference ΔTiis then the time difference between the detection of the tooth edge located at the angular position θi-A and the detection of the immediately preceding tooth edge. If there are as many teeth24as there are positions θi, this direct time difference ΔTithus corresponds to the time difference between the transition from the angular position θito the contact point19and the transition from the angular position θi-1to the contact point.

An example of the measurement of the time between two successive teeth24by the sensing element22is shown inFIG.5, which represents the time between two successive teeth24as a function of a measurement sample number (each measurement sample is associated with an angular position θi). InFIG.5, a first curve C1represents the measurement of the direct time difference ΔTibetween two successive teeth24and a second curve C2represents a filtered time difference ΔTfilti, 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 teeth24equal to 80.

The deformation controlling device for wheel10includes a calculation module32.

The calculation module32is configured to calculate the value of the wheel radius R for each predefined angular position θiusing 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 Rifor the position θiusing the direct time difference ΔTiassociated with the angular position θi.

The calculation module32is further configured to calculate the value of the wheel radius Rifor the predefined angular position θiusing the filtered time difference ΔTfiltishown inFIG.5, associated with the predefined angular position θi. The filtered time difference ΔTfiltiassociated with the predefined angular position θi corresponds to a weighted average of direct time differences ΔTifor multiple predefined angular positions θi.

The calculation module32is configured, for example, to calculate the filtered time difference ΔTfiltiby weighting the direct time differences ΔTifor multiple predefined angular positions by a Hann window. Such a weighting window can be seen, for example, inFIG.4, where p is a weighting coefficient. In particular, the calculation module32is configured to perform a weighted average of the k direct time differences whose angular position precedes the predefined angular position θiand 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 ΔTfiltifor a predefined angular position θiis calculated using the direct time differences ΔTifor angular positions between ΔTi-k and θi+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 ΔTfiltiis thus calculated using the direct time differences ΔTiassociated with the angular positions θiincluded on the quarter gearwheel surrounding the predefined angular position θi.

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

The calculation module32is configured to calculate the value of wheel radius Riof wheel4for each predefined angular position as the product of a predetermined wheel radius, for example an average wheel radius Rm, and the ratio between the direct time difference ΔTiand the filtered time difference ΔTfiltiobtained for said predefined angular position θi. The calculation module is configured to calculate the Rivalue of wheel4for each predefined angular position with the following equation.

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 inFIG.5for a train running at km/h with slight acceleration, a wheel with a nominal diameter of 1 meter and a number of gear teeth24equal to 80 is given by the graph shown inFIG.6, showing the value of the estimated radius as a function of the sample number.

FIG.7shows the wheel deformation obtained from the graph inFIG.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 system10is 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 system10.

The method includes a step of obtaining the parameter characterizing the angular velocity of the wheel for the plurality of predefined angular positions θ, followed by a step of calculating a value of radius Ri of wheel4for each predefined angular position i.

The obtaining step comprises obtaining, for the multiple predefined angular positions θion the wheel, while wheel4is rolling on the running surface8, a parameter characterizing an angular velocity of the wheel, when wheel4is in contact with the running surface8through said predefined angular position θi.

The obtaining step is implemented in particular when the rail vehicle is running at a substantially constant speed on running surface8. The obtaining step is preferably carried out when wheel4is running on running surface8without slipping.

The obtaining step includes the measurement by the sensor14of the parameter characterizing the angular speed of wheel4.

During the obtaining step, sensor14successively measures the direct time difference ΔTifor each predefined angular position θi. The direct time difference ΔTiis measured in particular when a predefined angular position θiis in contact with the running surface8, or in other words when the sensing element22detects the leading edge26of a tooth24at a position θi-A angularly offset from the position θiby angle A. The time difference ΔTiis then the time between the detection of the leading edge26of tooth24at the position θi-A and the detection of the leading edge26of the preceding tooth24.

After obtaining the direct time difference values ΔTi, a radius value Rifor each angular position θiis calculated in the calculation step. The calculation step is carried out in particular by calculation module32.

The calculation of each wheel radius Riuses the direct time difference ΔTiobtained for each angular position θi. The calculation of each wheel radius Rifor the predefined angular position θialso uses the filtered time difference ΔTfilti, where the filtered time difference is a weighted average of direct time differences ΔTifor multiple predefined angular positions θi. In particular, the filtered time difference ΔTfiltiis calculated as a weighted average of the direct time differences ΔT; 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 ΔTiis obtained for a predefined angular position θi. The direct time difference ΔTifor one wheel revolution is used to calculate a filtered time difference ΔTfiltifor one wheel revolution and a wheel radius Rifor one wheel revolution for a predefined angular position θi.

The wheel deformation controlling method thus includes the calculation of at least four wheel radius values Rifor each predefined angular position θi, in the calculation step The calculation step includes calculating a consolidated wheel radius value Ricfor each predefined angular position, with the consolidated wheel radius value Ricfor each predefined angular position θibeing calculated using the at least four wheel radius values Ricalculated for each predefined angular position θi.

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 Rifor each predefined angular position θj.

The use of a sensor14comprising a gearwheel20and a sensing element22is particularly advantageous since it allows economical controlling of wheel deformations, since the sensor14is, for example, a component of a rail vehicle anti-lock brake system.

The calculation of the radius value using the filtered time difference ΔTfiltiand in particular the use of a Hann window improves the accuracy of the calculation of wheel deformation4.

The calculation of a consolidated wheel radius Ricalso improves the accuracy of the wheel deformation calculation by excluding potential anomalies during measurement.