AU2005234619A1

AU2005234619A1 - Device and method for controlling the speed of a rail vehicle and system comprising devices of this type

Info

Publication number: AU2005234619A1
Application number: AU2005234619A
Authority: AU
Inventors: Johan De Graaf
Original assignee: Alstom Transport SA
Current assignee: Alstom Transport Technologies SAS
Priority date: 2004-11-17
Filing date: 2005-11-15
Publication date: 2006-06-01
Anticipated expiration: 2025-11-15
Also published as: EP1659018A1; ATE428598T1; FR2877885A1; FR2877885B1; EP1659018B1; AU2005234619B2; DE602005013890D1; ES2325545T3

Abstract

The device has Hall effect sensors to acquire rotation speed of each wheel of two pairs of mechanically independent front and rear wheels of a train. Speed limit determination units (72) find a speed limit for the train based on radius of curvature of a railway track. A train speed limitation unit (80) determines a control signal so that the speed limit does not exceed a determined speed limit. The radius of curvature is determined by a determination module (60) at a level of or each pair of wheels based on the rotation speed of each wheel. Independent claims are also included for the following: (A) a system to control speed of a rail transit car (B) a method to control speed of a rail transit car.

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S):: Alstom Transport SA ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Nicholson Street, Melbourne, 3000, Australia INVENTION TITLE: Device and method for controlling the speed of a rail vehicle and system comprising devices of this type The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5102 la- The present invention relates to a device and a method for controlling the speed of a rail vehicle provided with at least one pair of mechanically independent wheels which are arranged facing each other at one side and the other of the vehicle and a system for controlling the speed of a vehicle provided with a plurality of devices of this type.

Speed is a major movement parameter in the risk of derailment of a train which is travelling in a curve.

Systems for automatic limitation of the speed of a vehicle of the above-mentioned type are known, based on prior recognition of the curves in the path of the vehicle and a limit speed being associated with each of those curves.

This prior recognition is stored in the system which comprises a GPS receiver for positioning the vehicle relative to the stored curves.

When approaching one of these curves, the system limits the speed of the vehicle to the speed associated with this curve.

Generally, systems of this type do not provide a high level of precision for controlling the speed limitation, and particularly in sections of the journey comprising a number of curves, such as, for example, sections of urban railway.

Systems of this type thus tend to limit the speed of the vehicle, including the speed in straight lines of sections of 2 this type. This results in a longer journey time and heavier traffic.

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z The object of the present invention is to overcome the abovementioned problem by providing a device and a method for limiting the speed of the vehicle which does not lead to an unnecessary lengthening of the journey time.

To this end, the present invention relates to a device for controlling the speed of a rail vehicle provided with at least one pair of mechanically independent wheels which are arranged facing each other at one side and the other of the vehicle, characterised in that it comprises: means for acquiring the rotation speed of each wheel of at least one pair of wheels which are arranged facing each other; means for determining the radius of curvature of the rail track in the region of the or each pair of wheels in accordance with the acquired rotation speeds thereof; means for determining a limit speed for the vehicle in accordance with at least one radius of curvature determined; and means for limiting the speed of the vehicle, which means are capable of determining a control signal so that the speed does not exceed the limit speed determined.

According to specific embodiments, the device comprises one or more of the following features: the means for determining the radius of curvature comprise: means for determining the longitudinal speed of each wheel of the pair of wheels in accordance with the acquired rotation speed of that wheel; and means for calculating the radius of curvature of the rail track in accordance with the longitudinal speeds; -3the means for calculating the radius of curvature are capable of determining this in accordance with the O relationship: E xVg±+Vd

R=-

2 Vg Vd where R is the radius of curvature, E is the spacing between C the wheels of the pair of wheels, and Vg and Vd are the longitudinal speeds of the wheels of the pair of wheels; D the means for determining the limit speed are capable of determining a limit speed associated with the pair of wheels in accordance with the relationship: VL xx xR where VL is the limit speed, R is the radius of curvature of the rail track in the region of the pair of wheels, and a and Sare predetermined parameters; the vehicle comprises a torque-controlled motorisation system for driving the wheels of the vehicle, and the limitation means comprise regulation means which are suitable for determining a torque target for the motorisation system in accordance with the speed of the vehicle and the limit speed determined based on a predetermined control law; it further comprises means for selecting, in order to control the motorisation system, the minimum value from among the torque value determined by the control means and a torque value which is transmitted by the driver of the vehicle; it further comprises means for activating/deactivating the speed limitation carried out by the limitation means in accordance with predetermined conditions relating to the sliding action of the wheels of the pair of wheels; the activation/deactivation means comprise means for determining a value which is representative of the sliding -4- C action and means for comparing this to a predetermined threshold value, and the speed limitation is deactivated if 0 Z the value representative of the sliding action is greater Vthan the threshold value; and the activation/deactivation means activate the speed C limitation if at least the representative value of the D sliding action is less than the threshold value for a S predetermined period of time.

S Another aspect of the invention is a system for controlling the speed of a rail vehicle.

According to a first embodiment, the system for controlling the speed of a rail vehicle is provided with a plurality of pairs of mechanically independent wheels which are arranged facing each other at one side and the other of the vehicle, and is characterised in that it comprises: a plurality of devices of the above-mentioned type associated respectively with pairs selected from the plurality of pairs of wheels; and means for selecting, from among the control signals determined by the devices, the signal which corresponds to the minimum limit speed.

According to a second embodiment, the system is provided with a plurality of pairs of mechanically independent wheels which are arranged facing each other at one side and the other thereof, and is characterised in that it comprises: at least one device of the above-mentioned type associated with a pair of wheels selected from the plurality of pairs of wheels; 5 C means for acquiring the rotation speed of each wheel of at least another pair of wheels selected from the plurality of 0 z pairs of wheels; q means for determining the radius of curvature of the rail track in the region of the or each other pair of wheels selected from the plurality of pairs of wheels; and means for selecting the minimum value from among the radii of curvature determined by the at least one device, and the means for determining the radius of curvature associated with the other pair of wheels, and the means for determining the limit speed of the at least one device are capable of determining this limit speed in accordance with the minimum value selected from among the radii of curvature; the selected pairs comprise the outermost pairs from the plurality of pairs of wheels of the vehicle.

Another aspect of the invention is a method for controlling the speed of a rail vehicle provided with at least one pair of mechanically independent wheels which are arranged facing each other at one side and the other of the vehicle, characterised in that it comprises the steps: of acquiring the rotation speeds of each wheel of at least one pair of wheels which are arranged facing each other; of determining the radius of curvature of the rail track in the region of the or each pair of wheels in accordance with the acquired rotation speeds thereof; of determining a limit speed for the vehicle in accordance with at least one radius of curvature determined; and of limiting the speed of the vehicle so that the speed does not exceed the limit speed determined.

The present invention will be better understood from a reading of the following description, given purely by way of -6example and with reference to the appended drawings, in which identical reference numerals refer to identical or similar 0 z elements, and in which: Figure 1 is a schematic view of a train provided with a system for controlling the speed according to the invention; Figure 2 is a schematic view of a device for controlling the speed of the train within the structure of the system of SFigure 1; n Figure 3 is a schematic view of another embodiment of the control device within the structure of the system of Figure 1; Figure 4 is a flow chart of the operation of the system of Figure 1; and Figure 5 is a schematic view of another embodiment of the system of Figure 1.

In the following, the terms "left", "right", "front" and "rear" are defined relative to the orientation of the train of Figure i.

Figure 1 schematically illustrates a train 10 which is travelling in a curve of a rail track 12 and which is moving, for example, in the direction indicated by arrow F.

The train 10 is constituted by a plurality of bogies 14a, 14b, 14c which each comprise a pair of independent front wheels 16g-16d, 20g-20d, 24g-24d and a pair of independent rear wheels 18g-18d, 22g-22d, 26g-26d.

In the example illustrated in this instance, the wheels of each of the pairs are arranged facing each other at one side and the other of the train 12 and are mechanically independent, that is to say, not driven by the same axle.

-7- For example, the train comprises motorised bogies 14a, 14c which are each provided with a first motor 28g, 30g for O driving the left-hand wheels 16g, 18g, 24g, 26g thereof and a z second motor 28d, 30d for driving the right-hand wheels 16d, 18d, 24d, 26d thereof.

The train also comprises passive bogies 14b, that is to say,

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with no motorisation system, whose left-hand wheels 20g, 22g (Ni and right-hand wheels 20d, 22d are fixed, respectively, to Sindependent shafts.

The motors 28g, 28d, 30g and 30d are controlled from a control station 32a, 32b by means of a driver activating a torque demand lever 34a, 34b, as known per se.

The control station 32a, 32b comprises a console 36a, 36b for controlling the speed of the train, which console is connected to each motor of the motorised bogies, using a CAN, FIP, MVB or Ethernet bus 40, for example.

Several pairs of mechanically independent right-hand and left-hand wheels are selected so that each of their wheels is provided with a rotation speed sensor 42g, 42d, 44g, 44d, 46g, 46d, 48g, 48d, 50g, 50d, 52g, 52d, for example, a Hall effect sensor which is associated with a toothed wheel fixed to the axle of the wheel. In a variant, for a wheel which is driven by a motor, the rotation speed sensor is a motor speed sensor which is connected to a module for multiplying the speed measured by the reduction ratio of the motor.

Advantageously, at least the outermost pairs of mechanically independent wheels are selected so as to be provided with speed sensors, in this example, the pair of wheels 16g-16d -8and the pair of wheels 26g-26d for reasons which will be explained in greater detail below.

0 z SIn a variant, a single pair of mechanically independent wheels is selected to control the speed of the train.

The rotation speed sensors are connected to the control

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console 36a, 36b via the bus 40 in order to transmit their measurements to it.

c' The control console 36a, 36b comprises, associated with each of the pairs of wheels provided with sensors, a device 54a, 54b for controlling the speed of the train. This control device 54a, 54b determines a torque target C for the motors in accordance with the acquired rotation speeds of the wheels and transmits this to means 56a, 56b for selecting the minimum value Cmin from the values determined by each control device 54a, 54b associated with a respective pair of wheels, as will be explained in greater detail below.

A control device of this type is illustrated in Figure 2.

The control device comprises a unit 60 for determining the radius of curvature Rc in the region of the pair of wheels with which it is associated. The unit 60 comprises means 62, 64 for determining the longitudinal speed Vg, Vd of each of the right-hand and left-hand wheels in accordance with the respective acquired rotation speeds og, (d thereof, for example, in accordance with the relationship: Vi Ri x coi (1) where Vi is the longitudinal speed of one of the left-hand or right-hand wheels, Ri the radius thereof, and wi the acquired rotation speed thereof.

-9- In a variant, other models for calculating the longitudinal 0 O speed are used, such as models for estimating the sliding Saction of the wheel, dynamic models of the train,...

The longitudinal speeds Vg, Vd of the left-hand and righthand wheels determined in this manner are transmitted to

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means 66 for calculating the radius of curvature Rc in the Sregion thereof according to the relationship: vEV (RcE g +Vd (2) 2 Vg-Vd where E is the spacing between these two wheels.

When the right-hand and left-hand wheels of the pair of wheels are travelling over a section of the rail track which is substantially only slightly curved, their longitudinal speeds Vg and Vd are substantially equal. The inversion of the term Vg-Vd of the relationship may thus result in numerical problems, so that the radius of curvature Rc calculated may not be representative of the actual radius of curvature of the rail track.

Advantageously, the control device comprises means 68 for verification and correction of the numerical results transmitted by the calculation means 66.

For example, the means 68 are capable of selecting the maximum value from the radius of curvature Rc calculated and a predetermined value stored in data storage means This value which is, for example, 25 m, is determined by the features of the rail network.

10 The resultant radius of curvature Re of this selection is then transmitted to means 72 for determining a limit speed VL 0 for the train.

In The means 72 comprise, for example, a predetermined mapping of speed values in accordance with radius of curvature values NO which have been determined experimentally.

(cN SIn a variant, the means 72 are suitable for determining the limit speed VL in accordance with the relationship: VL x x RC where u and A are parameters which are predetermined experimentally and which are stored in the data storage means For example, a and g are 3.6 and 0.65 m/s 2 respectively.

The limit speed VL is then transmitted to a unit 74 for activating/deactivating the speed limitation system of the train.

The unit 74 comprises means 76 for selecting from this limit speed VL and a predetermined value stored in the data storage means 70. This selection is carried out in accordance with a selection signal Sel, as will be explained in greater detail below.

The means 76 transmit the selected value to means 78 for filtering the output of the selection means 76. These means 78 comprise, for example, a filter which implements a time ramp in order to move in a continuous manner from a previously selected value to a value which is newly selected by the means 76. This allows the effects of a discontinuous commutation between two values for the output of the selection means 76 to be compensated for.

11 The limit speed VL at the output of the filtering means 78 0 Z is transmitted to a unit 80 for limiting the speed of the train.

h The limitation unit 80 comprises means 82 for determining the ID speed of the train V, which means are suitable, for example, 0 for calculating the mean of the longitudinal speeds Vg and Vd Vdetermined by the means 62, 64 for determining the C longitudinal speeds.

The unit 80 also comprises regulation means 84 which receive the limit speed VL of the attenuation means 78 as a target and the speed V of the train as a measurement.

In one variant, the regulation means 84 receive the speed V of the train from acquisition or determination means which are conventionally provided in the train, so that the unit does not comprise means 82 for determining this speed.

The means 84 are capable of calculating, in accordance with the speed V of the train and the limit speed VL, a control torque target CC for the motors of the train based on a predetermined regulation law.

This regulation law is determined so that the application of the regulation target CC as a control signal for the motors causes the speed V of the train to be regulated at the limit speed VL. This regulation law is also advantageously determined so that the speed V does not exceed the limit speed VL. 12 C The torque target CC is transmitted to means 86 for selecting the minimum value from this and a torque target CCC z transmitted by the driver of the train from the control station using the torque demand lever.

C When a wheel slides, the determination of the longitudinal speed thereof may be imprecise or incorrect. Therefore, all Sof the calculations based on a speed of this type are also Sunsatisfactory.

The activation/deactivation unit 74 is suitable for activating or deactivating the speed limitation of the vehicle relative to the speed VL determined by the means 72 for determination in accordance with predetermined conditions relating to the sliding action of the right-hand and lefthand wheels of the pair of wheels.

To this end, the unit 74 comprises means 88 for determining a value G which is representative of the sliding action of the right-hand and left-hand wheels. The means 88 receive the longitudinal speeds Vg and Vd determined and are capable of calculating the value G in accordance with the relationship: G=jVd-Vg The means 88 transmit the value G calculated to means 90 for comparing this to a predetermined threshold value which is, for example, 1.8, and which is stored in the storage means The result of this comparison is transmitted to a time counter 92 which is activated as soon as the value G is lower than the threshold value thereof. The counter 92 transmits the counter value thereof to means 94 for comparing this to a predetermined threshold value, for example, 2s, stored in the storage means 13 This threshold value is also determined experimentally and z corresponds to the period of time after which it is i substantially certain that none of the wheels is sliding.

The unit 74 also comprises means 96 for diagnosing the operating state of the rotation speed sensors associated with

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C the wheels, for example, in accordance with the measurements V) Og, (d transmitted thereby, as known per se.

The results of the comparison of the means 90 and 94 and the result of the diagnosis of the operating state of the rotation speed sensors are transmitted to means 98 which carry out the AND function and which transmit the selection signal Sel to the selection means 76.

In this manner, if the wheels are not sliding, at least for a predetermined period of time, and if the sensors are operating in a satisfactory manner, the means 76 select the limit speed VL determined by the means 72.

Otherwise, the predetermined value received by the selection means 76 from the storage means 70 is selected.

This value, which is the maximum speed authorised on the network, for example, 70 km/h, is sufficiently high for the torque target CC calculated by the means 84 to be greater than the torque target CCC transmitted by the driver. The target CCC is thus selected by the means 80, with the limitation carried out by the unit 80 therefore being deactivated.

14 Figure 3 illustrates another embodiment of the control device according to the invention. This embodiment differs from that z described above in that the activation/deactivation of the speed limitation in accordance with the sliding action of the wheels of the pair of wheels is carried out at the output of the unit 60 for determining the radius of curvature Rc.

As illustrated in Figure 3, the activation/deactivation unit 74 comprises selection means 99 which receive at the input the radius of curvature Rc calculated by the unit 60 and a predetermined radius of curvature value stored in the data storage means The means 99 are capable of selecting, and transmitting to the means 68, one or other of the values received at the input in accordance with a signal Sel which is determined in a similar manner by the same elements of the unit 74 described above with reference to Figure 2.

More particularly, if the wheels do not slide, at least for the predetermined period of time stored in the storage means and if the rotation speed sensors associated with the wheels of the pair of wheels operate in a satisfactory manner, the means 99 select the radius of curvature Rc determined by the means Otherwise, the means 99 select the input value stored in the storage means 70. This value is determined as being sufficiently large, for example, 1000 km, for its use as a radius of curvature in the following calculation elements to deactivate the speed limitation of the train.

15 C If the train is provided with a single device according to the invention associated with a pair of right-hand and lefthand wheels of the train, the torque target C is transmitted to the motors in order to control them.

If the train is provided with a plurality of devices according to the invention, each associated with a selected pair of mechanically independent wheels which are arranged facing each other, all the torque targets C determined by these devices are transmitted to means for selecting the minimum value from these torque targets C.

In a variant, the means 86 for selecting the minimum value from the regulation torque target CC and the target CCC transmitted by the driver for any device from the plurality of devices are capable of receiving the control torque targets CCC of the other devices and selecting the minimum value from these and the torque target CCC transmitted by the driver.

The minimum value selected from the torque targets is transmitted to the motors in order to control them. This minimum value corresponds to the minimum value of the limit speeds determined by the plurality of devices so that the vehicle speed does not exceed this minimum value of the limit speeds.

The operation of the control system comprising devices according to the embodiment of Figure 2 described above is explained below with reference to the flow chart of Figure 4.

In an initialisation step 100, the various elements of the system are activated.

16 In a subsequent step 102, an acquisition of the rotation 0 z speeds cog, Od O of the right-hand and left-hand wheels of each n pair of wheels selected is carried out.

O At 104, the longitudinal speeds Vd, Vg of the pair of wheels are determined, as well as the radius of curvature Rc, the Svalue G which represents the sliding action of the wheels of Sthe pair of wheels, the diagnosis of the operating state of the rotation speed sensors associated with these wheels and the speed V of the train.

In a subsequent step 106, the maximum value Rc from among the radius of curvature Rc determined and the associated threshold value is selected, and the limit speed VL determined in accordance with this maximum value.

The conditions in terms of the sliding action of the wheels are tested at 108 and, if they are satisfactory, the limit speed VL is selected at 110. Otherwise, the predetermined value of the limit speed is selected at 110.

The following operating step 112 is the calculation of the torque target CC in accordance with the speed V of the train and the selected value VL for the limit speed.

This step 112 is followed at 114 by the selection of the minimum value from among the torque target CC and the target CCC transmitted by the driver of the train.

The step 114 returns to the acquisition step 102 in order to perform a new calculation cycle.

17 C The torque target selected at 114 is then transmitted, at 116, to the means for selecting the minimum value from among the z torque targets determined for all the selected pairs of wheels, and the torque target selected transmitted to the means for controlling the motors of the train.

If the system comprises a plurality of devices according to the second embodiment described with reference to Figure 3, the previous step 106 first consists in testing the conditions in terms of the sliding action of the wheels and selecting the radius of curvature determined by the means if they are satisfactory or otherwise selecting the value of the radius of curvature stored in the storage means 70. The maximum value Rc from among the value selected by the means 99 and the value which is stored in the means 70 and which is associated with the means 68 is selected and the limit speed VL is determined in accordance with this maximum value.

The step 106 then returns directly to the step 112 described above.

Another embodiment of the system for controlling the speed of the train in accordance with the speeds of the wheels of a plurality of selected pairs of mechanically independent right-hand and left-hand wheels is illustrated in Figure The system of Figure 5 comprises elements which are identical to those described with reference to Figure 3. The elements which are identical to those of Figure 3 are indicated by the same reference numerals and are not described in this instance for reasons of brevity.

18 This system comprises at least one device of the type described above with reference to Figure 3, associated with a 0 O pair of wheels selected from the plurality of pairs of wheels, n the portion of this device which is capable of calculating the limit speed for the train and the regulation torque target CC being common to all the selected pairs of wheels, as explained in greater detail below.

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Each pair of wheels selected, for example, 3 in number, is Sassociated with a device 200a, 200b, 200c capable of determining the radius of curvature Rca, Rcb, Rcc of the rail track in the region of the pair of wheels and a signal Ta, Tb, Tc, which represents the occurrence of a sliding action of the pair of wheels.

This device 200a, 200b, 200c comprises to this end a unit for determining the radius of curvature in the region of the pair of wheels, data storage means 70, and an activation/deactivation unit 74 described with reference to Figure 3, that is to say, means 88 for determining a value which is representative of the sliding action of the wheels of the pair of wheels, comparison means 90, a time counter 92, comparison means 94, diagnostic means 96, means 98 which carry out the AND function and which transmit a selection signal Ta, Tb, Tc, and means 99 for selecting from among the radius of curvature Rc determined by the unit 60 and a predetermined radius of curvature value in accordance with the selection signal transmitted by the means 98, as described above.

These means 88, 90, 92, 94, 96, 98 and 99 are arranged in a manner identical to that described with reference to Figure 3.

19 The system also comprises a device 210 for controlling the speed of the train.

0 z i This device 210 comprises a limitation unit 80 identical to that of Figures 2 and 3. This unit comprises means 82 for determining the speed of the train in accordance with the longitudinal speeds of the right-hand and left-hand wheels

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C determined by the unit 60 for determining the radius of curvature of any one of the devices 200a, 200b, 200c associated with a pair of wheels.

The device 210 also comprises selection means 212 which receive the radii of curvature Rca, Rcb, Rcc selected by the selection means 99 of the devices 200a, 200b, 200c, which means are capable of selecting the minimum value from these.

These selection means 212 are connected to means 68 for selecting the maximum value from among the minimum value of the radii of curvature selected by the means 212 and a predetermined value stored in storage means 214, as described above.

The device 110 also comprises means 72 for determining a limit speed VL connected to the means 68, in a manner identical to that described with reference to Figures 2 and 3.

The device 210 also comprises means 216 which receive the signals Ta, Tb, Tc for selecting from the means 98, which carry out the AND function, of the devices 200a, 200b, 200c associated with the pairs of wheels selected. The means 216 are capable of negating each of the signals Ta, Tb, Tc received and carrying out the AND function of the negated signals.

20 The means 216 transmit their result to selection means 218.

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z These means 218 receive the output of the means 72 and a value from the storage means 214 and are capable of selecting one or other of the values received in accordance with the value transmitted by the means 216, that is to say, the output of the means 72, if the value transmitted by the means 216 is 0 and, otherwise, the value of the storage means 214, and transmitting their output to the means 84 for regulating of the unit 80, as described above.

The limitation of the speed of the train is thus carried out in accordance with the minimum value of the radii of curvature calculated in the region of the pairs of wheels selected and the detection of the sliding action of at least one pair of wheels has the effect that this pair of wheels is not taken into account for the limitation of the speed of the train. If all the pairs of wheels have a sliding action, the limitation is deactivated.

The operation of the system described above is similar to that described with reference to Figure 4, with the difference that it comprises an intermediate step for selecting the minimum value from among the radii of curvature selected by the selection means 99 of the devices 200a, 200b, 200c for determining the radius of curvature, initiated following the step 104, the minimum radius of curvature selected being used in order to determine the limit speed VL in step 112 as described above with reference to Figure 4.

The operating step 116 of the system described above is also modified and consists in transmitting the torque target 21 selected at 114 to the means for controlling the motors of the train.

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z The selection of the outermost pairs of mechanically independent wheels allows the speed of the train to be controlled effectively when the train is travelling in a curve. As illustrated in Figure 1, the first bogie 14a travels in a straight section of the rail track 12, whilst the last bogie 14c travels in a curved section of the rail track 12. The speed of the train is thus limited as long as all the train is not substantially in a straight line, thus preventing any risk of derailment.

As can be seen, the device and the system according to the invention described above can be applied to any type of rail vehicle comprising at least one pair of wheels which are mechanically independent and which are arranged facing the vehicle.

The reference numerals in the following claims do not in any way limit the scope of the respective claims.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims

2. Device according to claim 1, characterised in that the means for determining the radius of curvature comprise: means (62, 64) for determining the longitudinal speed of each wheel of the pair of wheels in accordance with the acquired rotation speed of that wheel; and means (66) for calculating the radius of curvature of the rail track in accordance with the longitudinal speeds.
3. Device according to claim 2, characterised in that the means (66) for calculating the radius of curvature are capable of determining this in accordance with the relationship: 1 23 R=-x _g Vd 2 Vg Vd 0 z Swhere R is the radius of curvature, E is the spacing between the wheels of the pair of wheels, and Vg and Vd are the longitudinal speeds of the wheels of the pair of wheels. \O
4. Device according to claim 1, 2 or 3, characterised in that the means for determining the limit speed are capable of determining a limit speed associated with the pair of wheels in accordance with the relationship: VL =X xR where VL is the limit speed, R is the radius of curvature of the rail track in the region of the pair of wheels, and u and 0 are predetermined parameters. Device according to any one of the preceding claims, characterised in that the vehicle comprises a torque- controlled motorisation system for driving the wheels of the vehicle, and in that the limitation means (80) comprise regulation means (84) which are suitable for determining a torque target for the motorisation system in accordance with the speed of the vehicle and the limit speed determined based on a predetermined control law.
6. Device according to claim 5, characterised in that it further comprises means (86) for selecting, in order to control the motorisation system, the minimum value from among the torque target determined by the regulation means (84) and a torque target which is transmitted by the driver of the vehicle. 1 24
7. Device according to any one of the preceding claims, characterised in that it further comprises means (74) for 0 O activating/deactivating the speed limitation carried out by I the limitation means in accordance with predetermined conditions relating to the sliding action of the wheels of the pair of wheels. \O
8. Device according to claim 7, characterised in that the (Ni activation/deactivation means comprise means (88) for Sdetermining a value which is representative of the sliding C action and means (90) for comparing this to a predetermined threshold value, and in that the speed limitation is deactivated if the value representative of the sliding action is greater than the threshold value.
9. Device according to claim 8, characterised in that the activation/deactivation means activate the speed limitation if at least the representative value of the sliding action is less than the threshold value for a predetermined period of time. System for controlling the speed of a rail vehicle provided with a plurality of pairs (16g, 16d; 18g, 18d; 22g, 22d; 24g, 24d; 26g, 26d) of mechanically independent wheels which are arranged facing each other at one side and the other of the vehicle, characterised in that it comprises: a plurality of devices according to any one of the preceding claims associated respectively with pairs selected from the plurality of pairs of wheels; and means (86) for selecting, from among the control signals determined by the devices, the signal which corresponds to the minimum limit speed. 25 In
11. System for controlling the speed of a rail vehicle 0 z provided with a plurality of pairs (16g, 16d; 18g, 18d; V) 20d; 22g, 22d; 24g, 24d; 26g, 26d) of mechanically independent wheels which are arranged facing each other at one side and the other thereof, characterised in that it comprises: \O at least one device (lOOa, 100Ob, lOOc) according to any one of claims 1 to 9 associated with a pair of wheels selected 0 from the plurality of pairs of wheels; C means for acquiring the rotation speed of each wheel of at least another pair of wheels selected from the plurality of pairs of wheels; means (66) for determining the radius of curvature of the rail track in the region of the or each other pair of wheels selected from the plurality of pairs of wheels; and means (112) for selecting the minimum value from among the radii of curvature determined by the at least one device, and the means for determining the radius of curvature associated with the other pair of wheels, and in that the means (72) for determining the limit speed of the at least one device are capable of determining this limit speed in accordance with the minimum value selected from among the radii of curvature.
12. System according to claim 10 or 11, characterised in that the selected pairs comprise the outermost pairs from the plurality of the pairs of wheels of the vehicle.
13. Method for controlling the speed of a rail vehicle provided with at least one pair (16g, 16d; 18g, 18d; 20g, 22g, 22d; 24g, 24d; 26g, 26d) of mechanically independent wheels which are arranged facing each other at one side and 26 the other of the vehicle, characterised in that it comprises the steps: 0 Z of acquiring (at 102) the rotation speeds of each wheel of Sat least one pair of wheels which are arranged facing each other; of determining (at 104) the radius of curvature of the rail track in the region of the or each pair of wheels in Caccordance with the acquired rotation speeds thereof; of determining (at 104) a limit speed for the vehicle in Saccordance with at least one radius of curvature determined; and of limiting (at 116) the speed of the vehicle so that the speed does not exceed the limit speed determined. DATED this FIFTEENTH day of NOVEMBER 2005 Alstom Transport SA by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s)