GB2254154A - Detecting overheated bearings in railway vehicles - Google Patents

Abstract

A system for detecting overheating of rail vehicle wheel bearings in particular for vehicles having inboard bearings the overheating of which cannot be detected by conventional lineside detectors, uses an electric power generator mounted on the outer extremity of the vehicle axle 17 and which includes a power coil 29 which is switched on when a sensor 32 adjacent the inboard bearing 19 detects overheating of the bearing. The power coil 29, when switched on, heats up the casing 25 of the generator, which therefore emits infra-red radiation to trigger a conventional lineside hot box detector. A similar electric generator may also be used for other purposes. Casing 25 is mounted on a stub shaft 20 (which is fixed to vehicle axle 17) by bearings 24 and held against rotation by arm 26. A magnet 28 is fixed to the stub shaft 20 and thus rotates relative to coils 29, 30. <IMAGE>

Description

"Improvement in or relations to the detection of overheated bearings in railway vehicles" The invention relates to the detection of overheated bearings in railway vehicles.

In a railway system it is desirable, for safety reasons, to have early warning of the potential failure of wheel bearings. A faulty wheel bearing will usually overheat, due for example to loss or excess of lubricant or due to structural failure of a part of the bearing. Accordingly, there are in common use so-called hot box detection systems which monitor the temperature of wheel bearings while the rolling stock is in use.

Conventionally the wheel bearings of a railway vehicle are at the opposite outer extremities of a wheel set comprising two spaced wheels fixedly mounted on a common rotatable shaft. The bearing housings are therefore disposed outboard of the wheels and project slightly outwardly beyond the parallel rails.

The hot box detection system comprises fixed infra-red radiation detectors mounted alongside the track, at each side thereof, and positioned to sense infra-red radiation emitted from the heated bearings as the bearings pass over the detectors.

A normally operating bearing will run at about 50"C to 70"C above ambient temperature and the detectors are therefore arranged not to respond to the infra-red radiation resulting from this sort of temperature range.

If the bearing overheats, however, the wave length, and hence frequency, of the infra-red radiation from the bearing will change. If a trackside detector senses such a change in the infra-red radiation from a bearing passing over it, indicating that the bearing is overheating, an electric signal is sent by the detector to the next signal box along the line, so that the train driver can be warned of the overheating and bring the train to a halt.

However, there are now being designed wheelsets for railway vehicles in which the axle bearings are disposed inboard of the wheels.

Consequently, when rolling stock having such an arrangement runs on a track provided with conventional hot box detectors, such detectors, being outside the track, are not in an appropriate position to receive and detect infra-red radiation from the inboard bearings.

Since most rolling stock is of conventional design, having outboard bearings, it is not commercially feasible to provide additional detectors between the rails in a position to detect radiation from inboard bearings. The present invention therefore sets out to provide a system whereby overheating of such inboard bearings can be detected by the existing infra-red detectors located outside the rails.

According to the invention, a system for use in the detection of overheated bearings in a railway vehicle comprises a device for emitting infra-red radiation mounted on the vehicle in a position where infra-red radiation emitted thereby may be detected by a trackside infra-red detector, a sensor responsive to the temperature of a wheel bearing on the vehicle, and means controlling operation of said infra-red emitting device in response to signals from said sensor in such manner that the frequency of the infra-red radiation emitted by the device varies in accordance with variation in the temperature of said wheel bearing.

Thus, in operation of the system with rolling stock having inboard bearings, the sensor detects the actual temperature of the bearing and transmits this information to the infra-red emitting device. Should the inboard bearing overheat the signals from the sensor cause the infra-red emitting device to emit infra-red radiation which, to a greater or lesser extent, mimics the radiation which would be emitted from a conventional outboard bearing when it overheats. The conventional trackside detector detects this change in the infra-red radiation in the same way that it would detect the change in radiation from an actual overheated bearing, and transmits the appropriate signal to the next signal box so that the train can be brought to a halt.

The infra-red emitting device may be mounted anywhere on the vehicle where the infra-red radiation emitted thereby will be detected by a conventionally positioned infra-red detector. However, for convenience it may be mounted in the same location where a conventional outboard bearing would be situated. That is to say, the infra-red emitting device may be mounted on an outer extremity of a wheelset of the vehicle, for example on an end of the axle shaft of the wheelset.

Any type of device capable of emitting infrared radiation in a controllable manner may be employed.

Since such radiation is normally emitted by heated bodies, however, the device may conveniently comprise electrically heated means, the temperature of which is controlled in accordance with the temperature of said wheel bearing.

In the case where the device is mounted on an end of the axle shaft of a wheelset of the vehicle, the electrically heated means may comprise a non-rotatable power coil encircling magnetic means, such as a permanent magnet, rotatable with the axle shaft, whereby rotation of the magnetic means within the power coil generates an electric current in the coil, causing the coil to be heated. The power coil is preferably enclosed within an external casing to which heat is transmitted from the coil. Linkage means are preferably connected between the casing and a further part of the vehicle to substantially prevent rotation of the casing.

The generation of electric current in the power coil may be controlled by an electric switch adapted to open and close the coil circuit, said switch being under the control of electronic circuitry responsive to electrical signals from the aforesaid sensor.

There may be provided, also encircling magnetic means rotatable with the axle shaft, a further non-rotatable coil, the electric current generated in said further coil providing electrical power for said electronic circuitry. Said further coil may encircle the same magnetic means as the power coil and may be contained within the same casing.

The magnetic means may be mounted on an axial extension of the axle shaft of the wheelset, the aforesaid casing being mounted on said extension by means of rotatable bearings. The extension is preferably separately formed from the axle shaft and mounted on the end thereof. Preferably thermally insulating material is disposed between the extension and the end of the axle shaft.

In any of the above arrangements the aforesaid sensor may comprise the hot junction of a thermo-couple, the cold junction of the thermo-couple being at a location where it is subject to substantially ambient temperature.

Also in any of the above arrangements where the infra-red emitting device comprises electrically heated means, means are preferably provided for monitoring the temperature of said electrically heated means and comparing said temperature with the temperature of the axle bearing, operation of the electrically heated means being controlled to bring said temperatures substantially into agreement. Thus, the infra-red emitter mimics as closely as possible the effect of an overheated bearing at its own location.

Preferably, said control means are only operated to bring said temperatures into agreement if the axle bearing temperature exceeds a predetermined threshold value.

The invention includes within its scope a set of components suitable for use in a system of any of the kinds referred to above, said components including a device for emitting infra-red radiation, means for mounting the device on a railway vehicle, a temperature responsive sensor, and means for controlling operation of the infra-red emitting device in response to signals from said sensor in such manner that the frequency of the infra-red radiation emitted by the device varies in accordance with variation in the temperature to which said sensor is responsive.

The invention also includes a method of detecting overheated bearings in a railway vehicle comprising mounting on the vehicle a device for emitting infra-red radiation, said device being located in a position where the radiation emitted thereby may be detected by existing trackside detectors, determining the temperature of a wheel bearing on the vehicle, and controlling the infra-red radiation emitting device so that the frequency of the infra-red radiation emitted thereby is indicative of the temperature of the wheel bearing.

The invention further provides an electric generator, for use on a railway vehicle, comprising an extension shaft, having means for mounting it coaxially on an end of an axle shaft of the vehicle, magnetic means mounted on the extension shaft so as to be rotatable therewith, a casing surrounding the extension shaft and provided with linkage means for connection between the casing and a part of the vehicle to substantially prevent rotation of the casing, and a nonrotatable electric coil mounted within the casing and encircling the magnetic means on the extension shaft, whereby rotation of the magnetic means relatively to the coil generates an electric current in the coil.

The following is a more detailed description of a preferred embodiment of the invention, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic section through a conventional wheelset, on a railway vehicle, having outboard bearings, Figure 2 is a similar view showing a wheel set having inboard bearings, Figure 3 is a diagrammatic section through one end of a wheelset having inboard bearings, showing diagrammatically a detection system in accordance with the invention, and Figure 4 is a diagram illustrating the electrical control of the system.

In the conventional wheelset shown in Figure 1, the wheelset comprises two wheels 10 running on rails 11 respectively and fixedly mounted on a common axle 12.

The ends of the axle 12 project through and beyond the wheels 10 and the projecting ends are rotatable in bearings, the housings of which are indicated at 13. The bearing housings are usually spring mounted in a bogie frame (not shown).

Outside each rail 11 of the track is a hot box detector 14, pairs of such detectors being located at intervals along the railway line. Each detector 14 is responsive to infra-red radiation, indicated diagrammatically at 15, emitted from the wheel bearing 13 passing over it. If the wheel bearing is running normally, for example in a temperature range of 50"C to 70"C above ambient temperature, the detector 14 does not respond. Should a bearing on the vehicle overheat, however, the frequency of the infra-red radiation emitted thereby will change and if such change is sensed by one of the detectors 14 alongside the track, the detector will send a warning signal to the next signal box along the line. The train may then be stopped and the overheated bearing checked to establish the appropriate course of action.

Figure 2 illustrates diagrammatically a modified design of wheelset in which the axle shaft 12 is rotatable in bearings 16 which are disposed inboard of the wheels 10. It will be apparent that if such an inboard bearing overheats, the infra-red radiation which it transmits will not be detected by existing trackside detectors 14, since such detectors are too far away and are shielded from the overheated bearing by the rail and by the wheel itself.

Figure 3 illustrates diagrammatically a system in accordance with the invention whereby existing trackside infra-red detectors will be triggered by overheating of an inboard bearing.

Referring to Figure 3: One end of the axle shaft of the wheelset is indicated at 17 and the wheel fixedly mounted thereon is indicated at 18. The axle shaft 17 is rotatable in inboard bearings one of which is indicated at 19.

A stub shaft extension 20 is bolted coaxially on to the end of the axle shaft 17 by three bolts 21 which pass through an end flange 22 on the extension 20 into existing holes in the ends of the axle shaft 17. A disc of thermally insulating material 23 is disposed between the flange 22 and the end of the shaft 17.

Rotatably mounted on the end of the stub shaft 20 by means of bearings 24 is a casing 25. A torsion rod 26 is connected between the casing 25 and a fixed part 27 of the bogie frame to prevent rotation of the casing 25.

A soft iron cylindrical magnet 28 is pressed onto the stub shaft 20 inwardly of the bearings 24 and is encircled by a power coil 29 and a separate smaller coil 30, both coils being fixed within the casing 25 so as to rotate therewith around the magnet 28.

As the railway vehicle moves along the track the stub shaft 20 and magnet 28 rotate relatively to the non-rotatable casing 25, and hence also relatively to the coils 29 and 30. The relative rotation between the magnet and coils may cause electric currents to be generated in the coils. The smaller coil 30 is so arranged that current is generated therein whenever the magnet is rotating, and such current is used to power electronic control circuitry in a compartment of the casing 12 and indicated at 31. The generation of electric current in the power coil 29 is controlled, in a manner to be described, to heat the casing 25.

A hot junction 32 of a thermo-couple is embedded in the axle box close to the bearing 19. It is connected by a wire 33, which is protected from damage, to the electronic control circuitry 31 in the casing 25.

Figure 4 illustrates diagrammatically in greater detail the arrangement of the control circuitry.

The cold junction 34 of the thermo-couple is located in the electronics compartment of the casing 25, and is thermally insulated from the coils 29, 30 and from the stub shaft 20. A signal 35 is supplied by the thermocouple to the control circuitry 36 which is indicative of the temperature difference between the junctions of the thermo-couple.

The external temperature of the casing 25, heated by the power coil 29, is monitored by a temperature sensor 37 which supplies to the circuitry 31 a signal 38 indicative of that external temperature.

When the temperature difference monitored by the thermocouple exceeds a predetermined threshold value, indicating that the bearing is overheating, the electronic circuitry 31 closes a switch 39 in the power coil 29 circuit, so that electric current is generated in the power coil 29, heating up the casing 25. The circuitry 31 then continues to compare the temperature of the casing with the temperature difference detected by the thermo-couple and turns the switch 39 on and off in a manner to match the casing temperature to the temperature difference detected by the thermo-couple.

Thus, if the casing temperature is lower than the thermo-couple temperature, the switch 39 is closed, closing the circuit of the coil 29 so that electric current is generated in the coil by rotation of the permanent magnet 28 and the coil heats up, such heat being transmitted to the external casing 25. Once the external temperature of the casing matches the thermocouple temperature, the switch 39 is opened so that heating of the coil and hence the casing ceases.

By this means the external temperature of the casing 25 is substantially matched to the temperature of the bearing 19. Consequently, should the bearing 19 overheat, the external temperature of the casing 25 will be raised accordingly and the frequency of the infra-red radiation emitted by the casing 25, as a result of its rise in temperature, will be detected by a conventional trackside hot box detector, since such detectors are located so as to detect overheating of bearings which are located in the same position as the casing 25.

Although it is preferable that the electronics should be so arranged that the switch 39 is only closed to operate the power coil 29 and heat the casing when the temperature of the bearing rises above a predetermined threshold level, the arrangement could be such that the temperature of the casing 25 follows the temperature of the bearing at all times, even when such temperature is in an acceptable range.

The system may be arranged to be fail-safe.

Thus, the switch 39 may be normally closed, being opened under the control of the electronic circuitry. Then, if any failure of the electronics should occur, including loss of the signal from the hot junction of the thermocouple, the switch 39 will remain closed causing the power coil 29 to operate and heat the casing to a level where overheating will be detected. The power coil 29 may be provided with externally accessible contacts.to enable the coil to be checked by a simple circuit test.

Although the described arrangement is effective and convenient, it will be appreciated that the infra-red emitting device could be located at any position on the railway vehicle where the radiation emitted thereby will be detected by a conventional trackside detector. Thus the emitter might be fixedly mounted on part of the bogie frame. In that case other means may be provided for heating the emitter in a manner to mimic the heating of the inboard bearing.

Thus the device could comprise an electrical resistance heater, the temperature of which is controlled in accordance with the temperature of the inboard bearing.

Also, there are methods of generating infrared radiation which do not depend on heating, and any such alternative method of generating the infra-red radiation may be employed provided the frequency of the radiation produced is appropriate to mimic the radiation produced by an overheated bearing and thus trigger the hot box detector.

Although the invention is primarily intended to provide a system for detecting the overheating of inboard bearings on a railway vehicle, it is not limited to such application and a similar system could also be used for reliably detecting the overheating of conventional outboard bearings. In such a system, overheating of the outboard bearing is arranged to trigger an infra-red emitting device according to the present invention, and the infra-red emission would be detected by the lineside hot box detector as described above.

Such arrangement might be arranged to work more reliably than depending on the actual overheating of the outboard bearing to trigger the hot box detector directly. This is because the infra-red emitter can be arranged to be operated at any predetermined temperature of the bearing. It may thus, if required, be set to emit infra-red radiation sufficient to trigger the lineside detector at bearing temperatures which would not, in themselves, be sufficient to trigger the lineside detector directly. In other words the degree of sensitivity of the system to overheating can be adjusted to any required value, which is not normally possible with the conventional systems for detecting overheating of outboard bearings.

In the above described arrangement, electric power for the system circuitry is provided by the generator comprising the fixed coil 30 and the magnetic means 28 mounted on the rotating shaft extension 20. It will be appreciated that a similar arrangement for generating electric power may be employed for many other purposes within a railway vehicle where electric power is needed. The invention therefore also includes within its scope an electric generating unit similar to that shown in Figure 3 but for the sole purpose of generating electric power and therefore without the power coil 29 arranged to heat the casing 25 and without the other components particular to the described hot box detection system. Thus the power coil 29, instead of being arranged to heat the casing 25 when energised, could be arranged simply to generate electric power for use on the vehicle for other purposes.

The unit may thus provide a very convenient power generating package which may be bolted on to the end of the axle shaft of the vehicle, irrespective of whether or not it is also used in hot box detection.

Such further uses of the electric power generated by the unit might be as follows: Systems for control of acceleration and deceleration of the vehicle.

An anti-wheel-slide control device.

Monitoring of the operation of suspension, dampers, brake pads, etc.

Measurement of temperature and stress of components on the vehicle.

Use for interactive suspension changes, for example by control of solenoids effecting such changes.

Control of an air suspension system.

Monitoring the ride performance of the vehicle.

Monitoring wheel speed.

General data gathering, i.e. to power "black box" systems.

Powering vehicle identification devices, including automatic vehicle identification systems.

Controlling devices to indicate whether the vehicle is laden or unladen.

Triggering lineside equipment.

Claims (20)

1. A system for use in the detection of overheated bearings in a railway vehicle comprising a device for emitting infra-red radiation mounted on the vehicle in a position where infra-red radiation emitted thereby may be detected by a trackside infra-red detector, a sensor responsive to the temperature of a wheel bearing on the vehicle, and means controlling operation of said infra-red emitting device in response to signals from said sensor in such manner that the frequency of the infra-red radiation emitted by the device varies in accordance with variation in the temperature of said wheel bearing.

2. A system according to Claim 1, wherein the vehicle is provided with inboard bearings and wherein the infra-red emitting device is located where a conventional outboard bearing would be situated.

3. A system according to Claim 2, wherein the infra-red emitting device is mounted on an outer extremity of a wheelset of the vehicle, on an end of the axle shaft of the wheelset.

4. A system according to any of Claims 1 to 3, wherein the infra-red emitting device comprises electrically heated means, the temperature of which is controlled in accordance with the temperature of said wheel bearing.

5. A system according to Claim 4, wherein the infra-red emitting device is mounted on an end of the axle shaft of a wheelset of the vehicle, and wherein the electrically heated means comprise a non-rotatable power coil encircling magnetic means rotatable with the axle shaft, whereby rotation of the magnetic means within the power coil generates an electric current in the coil, causing the coil to be heated.

6. A system according to Claim 5, wherein the power coil is enclosed within an external casing to which heat is transmitted from the coil.

7. A system according to Claim 6, wherein linkage means are connected between the casing and a further part of the vehicle to substantially prevent rotation of the casing.

8. A system according to any of Claims 5 to 7, wherein the generation of electric current in the power coil is controlled by an electric switch adapted to open and close the coil circuit, said switch being under the control of electronic circuitry response to electrical signals from the aforesaid sensor.

9. A system according to Claim 8, wherein a further non-rotatable coil is provided, encircling magnetic means rotatable with the axle shaft, the electric current generated in said further coil providing electrical power for said electronic circuitry.

10. A system according to Claim 9, wherein said further coil encircles the same magnetic means as the power coil.

11. A system according to any of Claims 8 to 10, wherein the magnetic means is mounted on an axial extension of the axle shaft of the wheelset, the aforesaid casing being mounted on said extension by means of rotatable bearings.

12. A system according to Claim 11, wherein the extension is separately formed from the axle shaft and mounted on the end thereof, thermally insulating material being disposed between the extension and the end of the axle shaft.

13. A system according to any of Claims 5 to 12, wherein said magnetic means comprise a permanent magnet.

14. A system according to any of the preceding claims, wherein the sensor comprises the hot junction of a thermo-couple, the cold junction of the thermo-couple being at a location where it is subject to substantially ambient temperature.

15. A system according to any of the preceding claims, and where the infra-red emitting device comprises electrically heated means, wherein means are provided for monitoring the temperature of said electrically heated means and comparing said temperature with the temperature of the axle bearing, operation of the electrically heated means being controlled to bring said temperatures substantially into agreement.

16. A system according to Claim 15, wherein said control means are only operated to bring said temperatures into agreement if the axle bearing temperature exceeds a predetermined threshold value.

17. A set of components suitable for use in a system according to any of the preceding claims, said components including a device for emitting infra-red radiation, means for mounting the device on a railway vehicle, a temperature responsive sensor, and means for controlling operation of the infra-red emitting device in response to signals from said sensor in such manner that the frequency of the infra-red radiation emitted by the device varies in accordance with variation in the temperature to which said sensor is responsive.

18. A method of detecting overheated bearings in a railway vehicle comprising mounting on the vehicle a device for emitting infra-red radiation, said device being located in a position where the radiation emitted thereby may be detected by existing trackside detectors, determining the temperature of a wheel bearing on the vehicle, and controlling the infra-red radiation emitting device so that the frequency of the infra-red radiation emitted thereby is indicative of the temperature of the wheel bearing.

19. An electric generator, for use on a railway vehicle, comprising an extension shaft, having means for mounting it coaxially on an end of an axle shaft of the vehicle, magnetic means mounted on the extension shaft so as to be rotatable therewith, a casing surrounding the extension shaft and provided with linkage means for connection between the casing and a part of the vehicle to substantially prevent rotation of the casing, and a non-rotatable electric coil mounted within the casing and encircling the magnetic means on the extension shaft, whereby rotation of the magnetic means relatively to the coil generates an electric current in the coil.

20. A system for use in the detection of overheated bearings in a railway vehicle, substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.