WO2012042260A1

WO2012042260A1 - Condition monitoring of railway equipment

Info

Publication number: WO2012042260A1
Application number: PCT/GB2011/051835
Authority: WO
Inventors: Mark Glover; Simon Chadwick; James Mcquillan
Original assignee: Westinghouse Brake And Signal Holdings Limited
Priority date: 2010-09-28
Filing date: 2011-09-28
Publication date: 2012-04-05
Also published as: GB201016295D0

Abstract

A method for monitoring railway trackside equipment, said equipment comprising at least two relatively movable parts, by monitoring vibration levels associated with the equipment.

Description

CONDITION MONITORING OF RAILWAY EQUIPMENT

The present invention relates to condition monitoring of railway equipment and to the use of kinetic energy harvesting techniques and radio communications to remove the need for wired connections.

Background

Railway availability is highly dependent upon the correct operation of various items of trackside equipment. The following description considers point machines (which are also known as "switches" in the United States for example) in particular, but there are potential uses of this approach for other systems, such as level crossing barrier machines. Current technology monitors the operation of point machines by the use of sensors measuring parameters such as current drawn by electrical motors, force applied to moving parts of the points, relative position of switch rails and so on.

This current technology has a series of limitations including, but not limited to:

• Many parameters are inter-related - for example the current drawn depends on the voltage applied so therefore both need to be monitored to give a complete view of the system status.

• Monitoring current or voltage does not work for machines such as pneumatically or hydraulically operated point machines.

• The information received from such monitoring does not necessarily give useful information about the mode of failure. For example, although monitoring may indicate that e.g. more current is needed, or the voltage is lower than it should be, or the operation is taking longer than expected, it may not be possible to determine the associated cause.

Aims of the present invention It is an aim of the present invention to provide monitoring apparatus and methodology which overcomes the above problems. This aim is achieved by using vibration sensing for condition monitoring of such equipment, the vibration sensing providing an indication of the frictional forces acting on relatively movable parts of the equipment during said relative motion. This may include, for example, the raising of a barrier of level-crossing equipment, the movement of rails at a points machine etc.

Description of the invention

In accordance with a first aspect of the present invention there is provided a method for monitoring railway trackside equipment, said equipment comprising at least two relatively movable parts, by monitoring vibration levels associated with the equipment.

In accordance with a second aspect of the present invention there is provided a monitoring device for railway trackside equipment, said equipment comprising at least two relatively movable parts, the device comprising a vibration sensor, means for transmitting detected vibration levels to a remote location, and a kinetic energy harvester to provide electrical operating power to the sensor and transmitting means.

In accordance with a third aspect of the present invention there is provided railway trackside equipment fitted with the monitoring device in accordance with the second aspect. The present invention recognises that friction monitoring devices may provide an accurate measurement, through analysis of stress waves through particular components, of the friction encountered by trackside machines with relatively movable, e.g. relatively rotating, parts. They measure vibrations at a point on a device, and may be operable to record vibration levels over a period of time. Further analysis is possible using techniques such as Fourier transformations to translate such information into the frequency domain, thus allowing further information to be determined such as the presence of vibrations at a particular frequency which may be due to, for example, the correct operation of the point motor. The present invention further recognises that appropriate placement of a friction analyser on a point machine offers the opportunity to accurately determine the friction profile of a moving set of points - and therefore not only a view of the operation of the point machine, but also the lubrication status of the movable parts of the points or trackwork, the presence of any obstructions, and an overall view of the 'health' of the complete system. A series of recordings may be made with a healthy piece of equipment to enable a detailed "signature" to be built up, i.e. a time domain or frequency domain recording over a given time period. This signature will contain information such as the time taken for a set of points to operate, or peaks of vibration encountered as the points move throughout their "stroke". The vibration sensors can operate in one, two or three dimensions in order to determine vibration components in any direction, however in general one dimension of sensing is considered adequate. The sensors may be mounted non-intrusively, for example by simple gluing or otherwise bonding to a machine of interest, and so may be applied to any suitable machine without adversely affecting its performance. They can therefore directly pick up vibrations produced by movement of the machine. Furthermore, the sensors are completely immune to the effects of traction.

Various types of vibration sensor may be used, including for example fibre-optic sensors, piezoelectric sensors etc, as will be apparent to those skilled in the art.

As points are used, the "signature" of operation can change, due to, for example, problems with the mechanical structure of the points machine, or the mechanical parts which it operates. This can be manifested in increased friction (possibly due to poor lubrication of the moving parts of the point machine) compared with the "normal" signature, or an increased time period required for the operation of the points to occur.

Operations may be analysed using a computer algorithm which identifies such key parameters as operation time, maximum vibration sensed, whether vibration components outside the normally recorded range are sensed, and so on. Trends may be sought in the data in order to determine whether a fault is transitory, improving or deteriorating. Suitable trigger points may then be determined over a period of operation of a device to enable appropriate logging of faults, and for example calling of maintenance staff in order to meet the availability targets set by a particular railway.

The vibration analysers can communicate with central logging systems, either via a wired connection or via a short range radio communication system such as Bluetooth or Zigbee, therefore reducing the need for extended periods of time at trackside whilst installing the sensors.

In addition, kinetic energy harvesting techniques can be used to 'self power' the vibration analysers and associated radio systems, so that no local power supply is needed, again reducing the need for trackside access. As the train passes in the vicinity of the sensing device, the rail / track itself is deformed by the weight of the train, and the kinetic energy harvesting device translates this movement into stored energy, which in turn is used to power the local vibration analysers and associated communications equipment.

The present invention therefore provides for:

• The use of vibration analysis devices to measure the condition and performance of rotating or linear machines at the side of railway tracks - such as point machines - to determine, among other things, the friction encountered during operation.

• The use of such analysis to measure the condition and performance of any form of points machine, regardless of whether it is operated electrically, hydraulically or pneumatically.

• The use of short range radio systems to allow one or more vibration analyser to communicate with a trackside logging and processing device.

• The use of 'kinetic energy harvesting' techniques, to derive the energy required by such an analysis device and its radio communication system, thereby removing the need to have a wired connection to the device.

Detailed description The present invention will now be described with reference to the accompanying drawings, of which:

Fig. 1 schematically shows rail equipment fitted with a monitoring device in accordance with the present invention;

Fig. 2 schematically shows how detected vibration levels could change over time for "normal" operation of railway equipment; and

Fig. 3 schematically shows how detected vibration levels could change over time for "damaged" operation of railway equipment. Fig. 1 schematically shows a rail 1 of a railway line, with trackside equipment having at least two relatively movable parts, such as a points machine 2, provided in the proximity of the rail 1 . A vibration sensor 4 is mounted on the points machine 2 such that vibration of the points machine due to relative movement of the parts is detectable by the sensor 4. In practice, the sensor 4 may be mounted directly on the machine 2, or on a vibration-transmitting extension of the machine 2, or sufficiently close to it to detect the vibration. The vibration sensor 4 may be operable to detect vibration components in one, two or three dimensions in order to determine vibration components in any direction. The sensor 4 is provided with means, in this case a wireless transmitter 5, for communicating with a processing means 7 of a central logging system provided at remote office location 3. The processing means 7 is correspondingly provided with means 8 for receiving the wireless transmission from the sensor 4. The wireless transmission may take various forms, for example using short-range protocols such as Bluetooth or Zigbee, or longer range radio frequency transmission. Alternatively, wired communication may be implemented (not shown).

Electrical power is provided to the sensor 4 and transmitter 5 by a kinetic energy harvester 6, operable to convert kinetic energy, for example from vibration of the points machine 2, or, as shown, the rail 1 caused by passing trains, into electrical energy.

The sensor 4, with transmitter 5 and kinetic energy harvester 6, is preferably formed as an integral unit or "blister", and may be releasably attached to the machine, for example magnetically mounted thereto, or screwed or clipped into place, enabling retrofitting of the sensor equipment unit to the machine 2. Alternatively, some or all of the sensor equipment components may be permanently mounted on the machine 2, for example by gluing, bonding e.g. during initial construction of the machine 2.

In use, the sensor 4 is operable to transmit data corresponding to detected vibration levels to the processing means 7 over a time period. The vibration levels may be detected at intervals during the period, or continuously over the period, depending on the type of vibration sensor used. In the extreme case, the sensor 4 may transmit vibration level data continuously as long as it is sufficiently powered. Alternatively, the sensor 4 may be configured to commence transmission when a vibration level is detected having a predetermined signature, for example when it exceeds a predetermined threshold level. In a yet further alternative, the sensor 4 may be instructed to commence transmission when the points machine 2 is operated, in which case the sensor 4 must be provided with input means for receiving such an instruction.

Processing means 7 is operable to monitor, log and interpret or assess the received vibration level data. Ideally, a series of recordings are made with properly functioning trackside equipment to enable a detailed "signature" to be built up, i.e. a time domain or frequency domain recording over a given time period. This signature will contain information such as the time taken for a set of points to operate, or peaks of vibration encountered as the points move throughout their "stroke". A computer algorithm is employed which identifies such key parameters as operation time, maximum vibration sensed, whether vibration components outside the normally recorded range are sensed, and so on. Operational faults of the machine 2 may be identified using standard condition monitoring techniques, for example identifying characteristic signatures of the vibration level, referring to lookup tables etc. Trends may be sought in the data in order to determine whether a fault is transitory, improving or deteriorating. Since signatures associated with specific failure modes may be stored and identifiable, not only may a fault be detected, but also the cause of that fault.

Figs. 2 and 3 schematically show possible vibration level profiles associated with a points machine 2 over an operational cycle. Fig. 2 shows a "normal" profile, having a peak at each end of the profile, signifying the beginning and end of a point machine movement stroke, with the greatest amplitude of acceleration or deceleration respectively. Fig. 3 schematically shows a "damaged" profile, and here it can be seen that an additional vibration peak is present during the stroke, which could indicate, for example, mechanical wear, a missing tooth etc.

The above embodiments are exemplary only, and various alternatives will be apparent to those skilled in the art. For example, although the above description centres on points machines, any trackside equipment could be so monitored, for example railway points, frogs and level crossing barrier machines.

In the embodiment shown, the sensor 4 transmits data, via transmitter 5, directly to remote location 3. Depending on the local geography and the power available to the sensor 4, such an arrangement may be difficult to implement. For example, it is possible that a kinetic energy harvester as described might not be able to provide sufficient power to the transmitter 5 to enable direct communication with a geographically distant location 3, especially using radio frequency transmission. An alternative would be to provide a local transceiver, in the locality of the sensor 4, which is close enough to receive transmission from transmitter 5 and re-send this data directly to remote location 3, i.e. such that it acts similarly to a repeater station. Such a transceiver could be operable to receive transmissions from a plurality of such sensors, or even other railway equipment, for retransmission to location or elsewhere as required.

Claims

1 . A method for monitoring railway trackside equipment, said equipment comprising at least two relatively movable parts, by monitoring vibration levels associated with the equipment.

2. A method according to claim 1 , comprising the steps of:

a) providing a vibration sensor at the equipment, located so as to be able to detect vibration arising due to relative movement of the two relatively movable parts, b) using the vibration sensor to detect vibration levels over a time period, and c) assessing the detected vibration levels.

3. A method according to claim 2, comprising the step of providing processing means at a location remote from the trackside equipment, and wherein step c) includes sending the detected vibration levels to the said processing means, and assessing the detected vibration levels using the processing means.

4. A method according to claim 3, wherein the detected vibration levels are sent to the processing means using wireless transmission.

5. A method according to any of claims 2 to 4, wherein step c) includes logging the detected vibration levels.

6. A method according to any of claims 2 to 5, wherein the assessing of the detected vibration levels comprises identifying faults with the trackside equipment.

7. A method according to any of claims 3 to 6, wherein the vibration sensor is configured to send the detected vibration levels to the processing means only following detection of a vibration level having a predetermined signature.

8. A method according to claim 7, wherein the predetermined signature comprises a vibration level over a predetermined threshold level.

9. A method according to any preceding claim, wherein the vibration sensor is provided with a kinetic energy harvester to provide operating electrical power to the vibration sensor.

10. A method according to any preceding claim, wherein the trackside equipment comprises one of the group consisting of: railway points, points machines, frogs and level crossing barrier machines.

1 1 . A monitoring device for railway trackside equipment, said equipment comprising at least two relatively movable parts, the device comprising a vibration sensor, means for transmitting detected vibration levels to a remote location, and a kinetic energy harvester to provide electrical operating power to the sensor and transmitting means.

12. Railway trackside equipment fitted with the monitoring device according to claim 1 1 .

13. The railway equipment of claim 12, comprising a points machine.