WO2015096909A1

WO2015096909A1 - Emergency detection device for a rail vehicle and associated running gear, rail vehicle and emergency detection method

Info

Publication number: WO2015096909A1
Application number: PCT/EP2014/066248
Authority: WO
Inventors: Nathan Cartwright
Original assignee: Bombardier Transportation Gmbh
Priority date: 2013-12-23
Filing date: 2014-07-29
Publication date: 2015-07-02

Abstract

A wheel set assembly (10) for a rail vehicle comprises a wheel axle (12), a pair of wheels (14) attached to the wheel axle (12), a pair of axle boxes (16) for rotatably supporting the wheel axle (12) about a transverse axis of rotation (100), and a pair of rail guards (18) each protruding from a respective one of the axles boxes in a travel direction perpendicular to the transverse axis (100). The wheel set assembly (10) is further provided with a cord (20) straightened between the rail guards (18) the cord comprising a conductor connected to and a detector (32) for detecting a change in a signal through the conductor upon deformation and/or break and/or release of the cord (20). The cord has a length spanning the the track guage such that the cord detects derailment of the wheel set or an obstacle on the track in front of the wheel set.

Description

EMERGENCY DETECTION DEVICE FOR A RAIL VEHICLE AND ASSOCIATED RUNNING GEAR, RAIL VEHICLE AND EMERGENCY DETECTION METHOD

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates to rail vehicles, in particular but not exclusively to lightweight rail vehicles, and in particular but not exclusively to driverless rail vehicles. It relates more specifically to the detection of an obstacle in front of a leading wheel set assembly of a running gear of a rail vehicle and/or to the detection of a derailment of a wheel set assembly.

BACKGROUND ART

[0002] EP 2 548 783 discloses an obstacle deflector attached to a frame of a bogie for a rail vehicle. The obstacle deflector includes a hinged beam placed close to the rail in front of the bogie with switches that are triggered if a significant object is stuck. Significant brackets attached to the bogie frame are necessary to get the beam down to rail level. These brackets are nearly always designed from steel and add weight to the bogie frame. As bogie vibration is most severe at the ends of the bogie where the deflector is mounted, it is difficult to design a structure that will not be excited. Moreover, the frame structure has to be designed to take such inertia loads from the obstacle deflector and brackets. As a result, the weight of the frame is increased.

[0003] Hence, there is a need for a lighter obstacle detector, which is suitable in particular for light rail vehicles.

[0004] An emergency detection device for detecting an obstacle on a track in front of a wheel set of a rail vehicle and/or a derailment of a wheel set of a rail vehicle is disclosed in OA6050A. The detection device comprises a cord straightened between two brackets, the cord having a length such as to span the track gauge. The cord is mechanically linked to a transducer for transmitting a pneumatic of electric warning signal and/or actuating an emergency brake. SUMMARY OF THE INVENTION

[0005] According to one aspect of the invention, there is provided an emergency detection device for detecting an obstacle on a track in front of a wheel set of a rail vehicle and/or a derailment of a wheel set of a rail vehicle, which comprises a cord straightened between two brackets, wherein the cord includes a conductor connected to one or more detectors for detecting a change in a signal through the conductor upon deformation and/or break and/or release of the cord, the cord having a length such as to span the track gauge.

[0006] The cord is extremely light compared to a deflector, so that a lightweight structure is achieved. Moreover, the cord has a low cross-sectional area and a low drag resistance, so that it can easily move through snow or floodwater without activating the detector and without collecting vast amounts of debris.

[0007] The conductor is preferably an optical or electric conductor. In the latter case, the detector is preferably able to detect an interruption of an electrical current in a circuit including the conductor.

[0008] According to one embodiment, the detector is able to detect a variation of impedance of the electric conductor. The system can be calibrated to recognise peaks in the impedance, in particular the resistance of the conductor (which correspond to a strain of the conductor) associated with impact forces from striking objects. This method means that the cord can stay attached to the rail guards and does not need reattaching if a minor obstacle gets struck. It will also be possible to estimate the mass of the object struck by monitoring the conductor strain during the impact and also the vehicle velocity. A controller can be connected to the detector for activating an alarm if an impedance, e.g. a resistance, of the electric conductor is above a predetermined threshold. The resistance detection method can also be programmed to disregard constant forces (e.g. that produced from moving through snow).

[0009] According to an embodiment, the brackets can be provided each with a terminal for attaching an end of the cord. Each end of the cord is preferably attached to the one of the terminals so as to be released upon application of a predetermined force on the cord. The assembly may further comprise a controller connected to the detector for activating an alarm if the cord is released or broken.

[0010] According to a preferred embodiment, the cord comprises at least two parts connected to one another by a mechanical fuse. [0011] The cord may comprise one or more reinforcing plastic threads to achieve a strong lightweight structure. Alternatively or additionally, the cord comprises a reinforcing plastic sheath, e.g. made of woven plastic fibres, surrounding the conductor. The sheath is preferably such as to reduce undesired vibration of the cord.

[0012] More generally, the cord can be provided with a vibration damper. [0013] According to another aspect of the invention, there is provided a running gear assembly for a rail vehicle, provided with an emergency detection device as described above, wherein the cord of the emergency detection device is straightened in front of a leading wheel set of the running gear assembly.

[0014] According to a preferred embodiment, the brackets constitute a pair of rail guards each of the rail guards protruding in front of one wheel of the leading wheel set with respect to a travel direction of the rail vehicle perpendicular to a rotation axis of the leading wheel set. The assembly takes advantage of the rail guards, which form a rigid and strong pre-existing structure.

[0015] According to one embodiment, each of the rail guards is fixed relative to one of the axle boxes for rota tab ly supporting the wheel set about the axis of rotation. In this advantageous configuration, the cord is not subject to primary suspension movements.

[0016] The running gear assembly of claim may further comprise a frame supported on the wheel axles by means of a primary suspension, in which case the rail guards can be fixed relative to the frame.

[0017] According to another aspect of the invention, there is provided a rail vehicle comprising at least one running gear as described above. According to another aspect of the invention, there is provided a rail vehicle provided with at least one emergency detection device as described above, wherein the cord of the emergency detection device is straightened in front of a leading wheel set of a running gear assembly of the rail vehicle. The brackets preferably constitute a pair of rail guards, each of the rail guards protruding in front of one wheel of the leading wheel set with respect to a travel direction of the rail vehicle perpendicular to a rotation axis of the leading wheel set.

[0018] According to another aspect of the invention, there is provided a method for detecting an obstacle on a track in front of a wheel set of a rail vehicle, comprising straightening a cord in a transverse direction of the wheel set between two wheel guards attached to axle boxes for guiding the wheel set, and detecting a deformation and/or a break of the cord. Preferably, the cord is straightened in the transverse direction so as to span a distance between the two wheels of the wheel set.

[0019] According still to another aspect of the invention, there is provided a method for detecting an obstacle on a track in front of a wheel set of a rail vehicle, comprising detecting an interruption of a current through an electric conductor extending in a direction parallel to a rotation axis of the wheel set, in front of the wheel set, so as to span a distance between the two wheels of the wheel set.

[0020] According still to another aspect of the invention, there is provided a method for detecting an obstacle on a track in front of a wheel set of a rail vehicle, comprising detecting an interruption of a light ray extending in a direction parallel to a rotation axis of the wheel set between a light source and a light detector, so as to span a distance between the two wheels of the wheel set. Whenever an obstacle crosses the light ray, the latter is interrupted and an alarm is triggered.

DESCRIPTION OF THE FIGURES

[0021] Other advantages and features of the invention will become more clearly apparent from the following description of a specific embodiment of the invention given as non-restrictive example only and represented in the accompanying drawings, in which: Fig. 1 is an isometric view of an instrumented leading wheel set of a running gear assembly according to one embodiment of the invention;

Fig. 2 is a front view of the instrumented wheel set of Fig. 1;

Fig. 3 is a side view of the instrumented wheel set of Fig. 1; - Fig.4 illustrates a detail of the instrumented wheel set of Fig. 1;

Fig. 5 illustrates an electric circuit associated with the instrumented wheel set of Fig. 1;

Fig. 6 illustrates a rail vehicle including an instrumented running gear according to an embodiment of the invention; - Fig. 7 illustrates a rail vehicle including two instrumented running gears according to another embodiment of the invention;

Fig. 8 illustrates a rail vehicle including an instrumented running gear according to another embodiment of the invention;

Fig. 9 illustrates a rail vehicle including an instrumented running gear according to another embodiment of the invention;

Fig. 10 illustrates an instrumented wheel set of a running gear according to another embodiment of the invention;

Fig. 11 is an isometric view of a detail of Fig. 9;

Fig. 12 is a front view of the detail of Fig. 10. [0022] Corresponding reference numerals refer to the same or corresponding parts in each of the figures.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0023] Referring to Figs. 1 to 3, a wheel set assembly 10 for a rail vehicle, in the present case a lightweight rail vehicle, comprises a wheel axle 12, a pair of wheels 14 attached to the wheel axle 12, and a pair of axle boxes 16 for rotatably supporting the wheel axle 12 about a transverse axis of rotation 100. Each axle box 16 is provided with a L-shaped rail guard 18 with a first branch 18.1 protruding in a travel direction perpendicular to the transverse axis and a second branch 18.2 extending from the forward end of the first branch 18.1 in the transverse direction away from the other rail guard.

[0024] A cord 20 is stretched between the rail guards 18 so a to span the distance between the wheels 14 and to at least partially overlap with the wheels in the transverse direction. In this particular embodiment, the cord 20 includes a metallic wire 22 and a protecting sheath 24 made of plastic material. As illustrated in Fig. 4, the cord 20 has crimped metallic ends 26, which are pressed into terminals 28 on the rail guards.

[0025] As illustrated in Fig. 5, the wire 22 is connected via the terminals 28 to an electric circuit 30 provided with a detector 32, and a control unit 34 connected to the detector 32 and to an alarm 36 in a driver's cabin to form an emergency detection device 37. The detector 32 and control unit 34 can be located on one of the axle boxes 16, or at a remote location on the rail vehicle.

[0026] In the embodiment of Fig. 5, the electric circuit 30 comprising the wire 22 is a safety loop of the vehicle, provided with a power supply 38. Other safety-related devices can be connected in series with the wire 22 in the safety loop. In this case, the detector 32 is a current sensor. As is well known in the art, any interruption of the current in the safety loop 30 is detected by the current sensor 32, and the control circuit 34 triggers the alarm 36.

[0027] Alternatively, the wire 22 is part of a dedicated electric circuit 30 with a power supply 38, a current sensor 32, a control unit 34 and an alarm 36, and the current sensor 32 is used not only to detect an interruption of the current, but also variations of the ohmic resistance of the wire 22. As is known, the ohmic resistance increases with the tensile force on the wire 22. Accordingly, it becomes possible to assess the mass of an obstacle colliding with the cord 20. [0028] As will be understood by one skilled in the art, the wheel axle can be part of a various types of running gears 40, e.g. a bogie as illustrated in Fig. 6 and 7 or a single axle running gear as illustrated in Fig. 8 or a bogie. In most cases, a primary suspension 42 will be provided between the axle boxes 14 and an intermediate frame 44 of the running gear, and a secondary suspension 46 will be provided between the intermediate frame 44 and the car body 48 of the vehicle 50. However, the wheel set assembly 10 of the invention can also be applied to less conventional running gears, e.g. without primary or without secondary suspension, with or without king pin. The location of the axle boxes with respect to the wheels may vary with the type of running gear. In particular the axle boxes may be located between the wheels as illustrated in the figures, or on the contrary they may be located outside the wheels. In each case, the rail guard can be integral with the axle box or attached thereto.

[0029] Alternatively, the rail guards 18 can be fixed to the intermediate frame 44 as illustrated in Fig. 7, or directly to the car body 18 as illustrated in Fig. 9. In each case, the cord is straightened between the rail guards 18 in a manner similar to the embodiment of Figs. 1 to 4.

[0030] The wheel set assembly 10 of the invention is intended for use at least as a leading wheel set of the rail vehicle 50. To further improve safety, the leading wheel set of each running gear can be provided with the emergency detection device of the invention, as illustrated in Fig. 9.

[0031] The wheel set operates as follows. Each terminal 28 has a predetermined pull-out force corresponding to a predetermined mass hitting the cord at a predetermined velocity. If the cable is hit with enough force to pull the terminal out of its socket (or snap the cable) then it breaks the electrical circuit provided by the cable. The cable has to be reset manually after each activation.

[0032] The emergency detection device 37 can alternatively or additionally be used to detect derailment of the wheel set 10. As the wheel 14 leaves the railhead, the wheel set 10 drops onto the sleepers or slab. This drop causes the emergency detection device 37 to strike the rail head and break the cord operating the emergency braking system of the rail vehicle 50. [0033] Referring now to Figs 10 to 12, a wheel set 10 according to another embodiment of the invention is provided with a cord 20 stretched between two wheel guards 18 fixed to the axle boxes 16 of the wheel set 10. The cord 20 has two parts 20.1, 20.2 attached to one another by means of a mechanical fuse 52. One end of the cord 20 is bolted to one of the wheel guards 18, while the other is bolted on a free end of a cantilever bracket 54 attached to the other wheel guard 18. The cantilever bracket 54 is instrumented with at least one, and preferably a set of strain gauges 56 connected to a temperature compensated Wheatstone bridge or half bridge to measure the deformation of the bracket 54. The strain gauges 56 are part of an emergency detection device 37: whenever the cord is hit by an obstacle, the cantilever bracket 54 is deformed and the strain gauges 56 deliver a signal that triggers an alarm to stop the rail vehicle 50. Additionally, the cord 20 can be provided with an internal wire connected to a current sensor. Hence, an impact with a heavier obstacle or at a higher speed, which results in the mechanical fuse being broken and the current through the wire being interrupted, is detected by the current sensor and triggers the alarm. Alternatively, or additionally, the cord 20 can be stretched with a sufficient tensile force, such that the cantilever bracket is always under strain. In such a case, any impact that breaks the mechanical fuse 52 will result in a release of the cantilever bracket, which will be detected with the strain gauges. [0034] The emergency detection device 37 can alternatively or additionally be used to detect derailment of the wheel set 10. As the wheel 14 leaves the railhead, the wheel set 10 drops onto the sleepers or slab. This drop causes the emergency detection device 37 to strike the rail head and break the cord operating the emergency braking system of the rail vehicle 50. [0035] A number of other variants are contemplated within the scope of the claims. In particular, the electric circuit for detecting the release, break and/or deformation of the wire included in the cord may rely on a DC or an AC power supply. Other components of the impedance can be measured, e.g. the inductance. The end of the cord may be soldered to the terminal so as to break above a predefined tensile force threshold. [0036] The cord can be provided with a light conductor instead of the electric conductor 32. Alternatively, the cord can be without conductor. In such a case, the detector can be a switch linked to an end of the cord or to an attachment interface between the rail guard and the cord. The switch is such that release of the cord results in a change of state of the switch.

Claims

An emergency detection device (37) for detecting an obstacle on a track in front of a wheel set of a running gear of a rail vehicle or a derailment of a wheel set of a running gear of a rail vehicle, wherein the emergency detection device comprises a cord (20) straightened between two brackets (18), characterised in that the cord (20) includes a conductor (22) connected to one or more detectors (32) for detecting a change in a signal through the conductor (22) upon deformation and/or break and/or release of the cord (20), the cord having a length such as to span a track gauge of the track.

The emergency detection device of claim 1, characterised in that the cord (20) comprises one or more reinforcing plastic threads.

The emergency detection device of claim 1 or claim 2, characterised in that the cord comprises a reinforcing plastic sheath (24) surrounding the conductor (22).

The emergency detection device of any one of claims 1 to 3, characterised in that the conductor (22) is an optical conductor.

The emergency detection device of any one of claims 1 to 3, characterised in that the conductor (22) is an electric conductor.

6. The emergency detection device of claim 5, characterised in that the detector (32) is able to detect an interruption of an electrical current in a circuit (30) including the conductor (22).

7. The emergency detection device of claim 5 or claim 6, characterised in that at least one of the one or more detectors (32) is able to detect a variation of impedance of the electric conductor (22).

8. The emergency detection device of the preceding claim, characterised in that it further comprises a controller (34) connected to at least one of the one or more detectors (32) for activating an alarm (36) if an impedance of the electric conductor (22) is above a predetermined threshold.

9. The emergency detection device of any one of the preceding claims, characterised in that the brackets (18) are provided each with a respective terminal (28) for attaching a respective end of the cord (20).

10. The emergency detection device of the preceding claim, characterised in that at least one end of the cord (20) is attached to the respective terminal (28) so as to be released upon application of a predetermined force on the cord (20).

1 1 . The emergency detection device of any one of the preceding claims, characterised in that the cord comprises at least two parts connected to one another by a mechanical fuse.

12. The emergency detection device of any one of the preceding claims, characterised in that it further comprises a controller (34) connected to the detector (32) for activating an alarm (36) if the cord (20) is released or broken.

13. A running gear assembly for a rail vehicle travelling on a track, characterised in that it is provided with at least one emergency detection device according to any one of the preceding claims, wherein the cord of the emergency detection device is straightened in front of a leading wheel set of the running gear assembly.

14. The running gear assembly of the preceding claim, characterised in that the brackets constitute a pair of rail guards (18), each of the rail guards protruding in front of one wheel of the leading wheel set with respect to a travel direction of the rail vehicle perpendicular to a rotation axis (100) of the leading wheel set.

15. The running gear assembly of claim 14, characterised in that each of the rail guards is fixed relative to an axle box (16) for rotatably supporting the wheel set about the axis of rotation (100).

16. The running gear assembly of claim 14, further comprising a frame supported on the wheel axles by means of a primary suspension, characterised in that each of the rail guards is fixed relative to the frame.

17. A rail vehicle, characterised in that it comprises a running gear according to any one of claims 13 to 16.

A rail vehicle, characterised in that it is provided with at least one emergency detection device according to any one of claims 1 to 12, wherein the cord of the emergency detection device is straightened in front of a leading wheel set of a running gear assembly of the rail vehicle.

The rail vehicle of claim 18, characterised in that the brackets constitute a pair of rail guards (18), each of the rail guards protruding in front of one wheel of the leading wheel set with respect to a travel direction of the rail vehicle perpendicular to a rotation axis (100) of the leading wheel set.

A method for detecting an obstacle on a track in front of a wheel set assembly (10) of a rail vehicle or a derailment of a wheel set assembly (10) of a rail vehicle, comprising straightening a cord (20) comprising a conductor in a transverse direction of the wheel set assembly (10) between two wheel guards (18) fixed relative to axle boxes (16) for rotatably guiding an axle (12) of the wheel set assembly (10), and detecting a change in a signal through the conductor upon deformation and/or break of the cord (20).