GB2575656A

GB2575656A - Oil plug

Info

Publication number: GB2575656A
Application number: GB1811734.1A
Authority: GB
Inventors: Rosinski Jarek; Rosinski Tomas; Lowry Steve; Nixon Matthew; Brierley Aidan
Original assignee: JR Dynamics Ltd
Current assignee: JR Dynamics Ltd
Priority date: 2018-07-18
Filing date: 2018-07-18
Publication date: 2020-01-22
Also published as: GB201811734D0

Abstract

An oil plug 301 for the drain port an oil-filled device contains at least one sensor 305, 306, 307 for monitoring an operating condition of the device. A wireless transmitter 310 transmits the sensor data to a remote receiver. The sensor may detect debris in the oil e.g. with a capacitive sensor having two capacitive plates 305a, 305b and a magnet 314 to attract ferrous metal debris. A Hall effect sensor may alternatively be used. Vibration, moisture, oil level or temperature sensors may also be provided in the plug. A charge coupled device may capture an image of particles in the oil. The plug is the shape of a conventional drain plug with a head 303 and threaded body 302 for retrofitting to e.g. a railway train gearbox or a pump. Several such plugs may communicate with a data analysis system. Data may be transmitted at predetermined intervals. The plug may have its own power source 308.

Description

Technical Field

The present invention relates to systems and apparatus for detecting operating conditions of oil-filled devices, for example, but not exclusively, for detecting operating conditions of oil-filled gearboxes.

Background

Railway trains include many components and systems that must work correctly to ensure safe operation. A notable example is the gearboxes used to drive the axle of the driving wheels of a train. Often such gearboxes are mounted directly on the axle. Such gearboxes comprise a housing which contains a gear wheel mounted (for example shrunk-fit) directly on the axle, and a pinion. The pinion is driven via a coupling, by an electric motor or diesel engine. Trains can have multiple driven wheels and therefore include several such gearbox/drive arrangements.

Because such gearboxes are mounted directly on the axle, failure of the gearbox during operation of the train could have catastrophic consequences, including derailment of the train. Accordingly, typically, such gearboxes are overhauled at regular intervals. A precautionary approach is usually taken, and such gearboxes are overhauled more regularly than might otherwise be required. Although this approach is often deemed essential to reduce to acceptable levels the chance of a safety-critical failure during operation, it is nonetheless expensive and wasteful as many safe and correctly functioning gearboxes are overhauled. Further, it is also well-known that overhauling well bedded-in gearboxes as part of precautionary maintenance can introduce problems in previously well-running gearboxes.

In certain circumstances, condition-based monitoring (CBM) can be used, where sensors in or proximate to a gearbox are used to detect issues such as: oil degradation, bearing failures or deterioration, gear failures, lack of oil, excessive vibrations or temperature. CBM is advantageous because problems that might lead to serious failure can be identified and the requirement for precautionary maintenance is thereby reduced.

Using conventional techniques, implementing CBM in rail gearboxes has not been successful due to the hostile environment in which train gearboxes operate. Impact from flying track ballast in particular means that it is difficult to avoid the instrumentation and associated wiring being damaged.

It is an aim of certain embodiments of the invention to address these problems.

Summary of the Invention

In accordance with a first aspect of the invention, there is provided an oil plug for fitting to an oil-filled device and for monitoring operating conditions of the device. The oil plug comprises one or more sensors, each sensor operable to detect an operating condition of the device and generate sensor data associated with the operating condition, and a wireless transmitter operable to transmit data associated with the sensor data to a receiver remote from the oil plug.

Optionally, the one or more sensors is an oil-debris detection sensor for detecting oil debris within oil of the oil filled device.

Optionally, the oil plug further comprises a magnetic part, proximate to the oil debris detection sensor, for attracting ferrous material.

Optionally, the oil-debris detection sensor is a capacitive sensor which detects oil debris by detecting changes in capacitance of the oil in the vicinity of the plug.

Optionally, the capacitive sensor comprises first and second capacitive plates separated by a gap open to ingress by the oil from the oil-filled device.

Optionally, the oil plug further comprises first and second electrodes for measuring an impedance of the oil across the gap.

Optionally, the first electrode is mounted on the first capacitive plate and the second electrode is mounted on the second capacitive plate.

Optionally, the oil-debris detection sensor is a Hall-effect sensor which detects oil debris by detecting changes in the magnetic field in the vicinity of the plug.

Optionally, one of the one or more sensors is a temperature sensor for detecting a temperature of the oil-filled device.

Optionally, one of the one or more sensors is a vibration sensor for detecting vibrations of the device.

Optionally, the sensor data from the vibration sensor comprises a crest factor value calculated as a ratio of the peak value of detected vibration during a sample period with the root mean square (RMS) value of the detected vibration during the sample period.

Optionally, one of the one or more sensors is a moisture sensor for detecting moisture within the oil.

Optionally, one of the one or more sensors is an oil level sensor for detecting an oil level within the device.

Optionally, one of the one or more sensors is a particle size sensor for detecting a particle size of debris within oil of the device.

Optionally, the particle size sensor comprises a charge coupled device for capturing images of the oil.

Optionally, the oil plug further comprises a processor arranged to periodically activate the one or more sensors to detect the operating conditions and generate the sensor data.

Optionally, the oil plug further comprises a memory, said processor adapted to store the sensor data in the memory.

Optionally, the processor is operable to control the wireless transmitter unit to periodically transmit the sensor data stored in the memory to the remote receiver.

Optionally, the processor is operable to control the wireless transmitter to transmit the sensor data at predetermined time intervals.

Optionally, the sensors and the wireless transmitter are substantially entirely enclosed within a body of the oil plug.

Optionally, the oil plug further comprises an opening sealed by a window transparent to radio signals transmitted from the wireless transmitter.

Optionally, the oil plug has a form-factor substantially corresponding to a conventional oil plug for the device.

Optionally, the oil plug comprises a threaded body and a head.

Optionally, the processor is adapted to control the wireless transmitter to transmit identification data for identifying the oil plug.

Optionally, the device is an oil-filled gearbox.

Optionally, the gearbox is a railway train gearbox.

Optionally, the device is a pump.

In accordance with a second aspect of the invention, there is provided a remote monitoring system comprising one or more wireless transceivers and a data analysis system. The wireless transceivers are operable to receive sensor data from one or more oil plugs according the first aspect of the invention and communicate said sensor data to the data analysis system, wherein said data analysis system is operable to process the sensor data to identify sensor data indicative of abnormal gearbox operation and responsive to identifying sensor data indicative of abnormal gearbox operation, generate an alert.

In accordance with certain aspects of the invention, a modified oil plug is provided which is equipped with sensors for monitoring the operating conditions of an oil-filled device such as a gearbox, and in particular a gearbox for a train. Advantageously, the modified oil plug further comprises a wireless transmitter for transmitting sensor data to a remote receiver for analysis. Operating conditions within the device can be monitored to identify potential problems that might require the device to be overhauled, inspected or replaced. Accordingly, the frequency with which devices are overhauled or replaced as a precaution can be safely reduced, reducing the on-going cost of operating the device.

Advantageously, in accordance with certain embodiments of the invention, certain components necessary to perform condition-based monitoring are housed in an oil plug along with a wireless transmitter. Accordingly, the requirement for external components, such as external wiring is reduced making the system less vulnerable.

Advantageously, the modified oil-plug typically takes the form-factor of a conventional gearbox oil plug meaning it can be readily retro-fitted. Furthermore, in certain embodiments, the provision of a wireless transmitter, transmitting collected sensor data, means that data can be collected by a remote unit (positioned away from the hostile environment within which a gearbox, such as a train gearbox, operates) for further analysis, or for onward transmission to an analysis system.

Various further features and aspects of the invention are defined in the claims.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings where like parts are provided with corresponding reference numerals and in which:

Figures 1 provides a simplified schematic diagram of a conventional arrangement for powering set of railway train wheels;

Figure 2a provides a simplified schematic diagram showing a cut-away view of a gearbox from the arrangement shown in Figure 1;

Figure 2b provides a simplified schematic diagram of a conventional oil drain port plug for use in a gearbox as depicted in Figure 2a;

Figures 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3i provide schematic diagrams of modified oil plugs in accordance with certain embodiments of the invention;

Figure 4 provides a schematic diagram of a modified oil plug in use in a gearbox; and

Figure 5 provides a simplified schematic diagram of a monitoring system arranged in accordance with certain embodiments of the invention.

Detailed Description

Figure 1 provides a simplified schematic diagram of a conventional arrangement for powering set of railway train wheels.

A gearbox 101 is mounted around an axle 102 connecting two train wheels 103, 104. The gearbox 101 includes an input shaft 105 driven via a coupling 106 by an electric or diesel motor 107. Mounted on the input shaft 105 within the gearbox 101 is a pinion 108 which meshes with and drives a drive gear wheel 109 which is connected to the axle 102. In this way, the motor 107 drives the train wheels 103, 104. The gearbox 101 is filled with lubricating oil.

Figure 2a provides a schematic diagram of a cut-away view of the gearbox 101 along line A shown in Figure 1.

The lubricating oil with which the gearbox is filled must be periodically changed and therefore the gearbox 101 is provided with an oil drain port 202 to drain used oil from the gearbox 101 and an oil refill port 201 to add fresh oil.

The oil refill port 201 is sealed by a removable oil refill port plug 203 and the oil drain port 202 is sealed by a removable oil drain port plug 204.

Typically, the oil refill port plug 203 and oil drain port plug 204 are provided by the same type of oil plug.

Figure 2b provides a schematic diagram of a conventional oil plug 207 which can be used to provide the oil refill port plug 203 and oil drain port plug 207.

The oil plug 207 includes a head 205 and a threaded body 206. Typically, the oil drain port 202 and oil refill port 201 comprise a threaded through-hole providing access to the inside of the gearbox 101 into which the body 206 of the plug 207 is screwed. The head 205 of the plug 207 is typically shaped to be manipulated by a tool such as a wrench or spanner.

Figures 3a, 3b and 3c provide simplified schematic diagrams of a modified oil plug 301 in accordance with certain embodiments of the invention.

The oil plug 301 is sized and dimensioned so that it can be used in place of a conventional removable oil plug used to seal the oil drain port or oil refill port of a gearbox of the type described with reference to Figure 1.

The plug 301 has a form factor which corresponds to that of a conventional oil plug (for example of the type described with reference to Figure 2b).

The modified plug 301 includes a threaded body 302 which is sized and dimensioned so that it can be screwed into a corresponding threaded hole of an oil drain port or oil refill port of a gearbox.

The plug 301 further includes a head 303, shaped to be engaged by a tool such as a spanner or wrench allowing the plug 301 to be rotated during installation or removal from the oil drain port.

Typically, the body 302 and head 303 of the plug are made from steel, stainless steel, or brass.

The plug 301 includes an inner cavity 304 within which is mounted a number of monitoring sensors.

The body 302 and head 303 of the plug can be formed using conventional manufacturing techniques such as milling, drilling etc.

The body 302 and head 303 of the plug can be formed with a cavity specifically for the purpose of providing a modified oil plug, or a conventional oil plug can be drilled out to provide the cavity 304 of the plug.

The inner cavity 304 includes a number of sensors 305, 306, 307, a processor and memory unit 309, a radio transmitter 310 and a power source 308.

Under control of the processor, each sensor is adapted to monitor a particular operating condition ofthe gearbox. Typically, each sensor is provided with electronics (for example an integrated circuit) adapted to convert measurement signals collected by the sensor into a sensor data signal (for example a binary code) which is sent via, a suitable data connection (not shown), to the processor. The processor is arranged to receive the sensor data signals from the sensors, perform any necessary processing on the sensor data and then control the radio transmitter to transmit a wireless data signal containing the sensor data, or data relating to (or data derived from) the sensor data to an external wireless receiver.

In certain embodiments, the wireless data signal is transmitted periodically (e.g. at predefined time intervals) and the sensor data may be collected more frequently than the wireless data signal is transmitted. Therefore, in between transmissions, the processor is arranged to store the sensor data to be transmitted in the next wireless data transmission in the memory.

To conserve power when the plug is deployed, typically, the sensors are only periodically activated. That is, for most of the time, they are in a “standby” state of low power consumption or entirely powered off. The processor is adapted to periodically activate the sensors, receive and store sensor data generated by the sensors and then power the sensors down.

In certain embodiments, the radio transmitter is part of a radio transceiver which is further operable to receive wireless signals. In certain embodiments, a command may be received via a wireless signal transmitted to the modified plug to transmit the sensor data and responsive to receipt of this command, the processor is arranged to control the transmitter to transmit the wireless data signal.

In the embodiment shown in Figure 3a, the modified plug 301 includes a debris detection sensor 305 which is adapted to detect debris in the oil of the gearbox. In the example depicted in Figure 3a, the debris detection sensor is a capacitive sensor, that is, a sensor arranged to detect changes in capacitance arising due to the presence of debris in the oil.

A plurality of pins 312 project from the end of the threaded body 302 attached to the end of which is a mounting platform 313 on which is fixed a magnet 314. A first capacitive plate 305a is attached to the end of the threaded body 302 and a second capacitive plate 305b is attached to the magnet 314. The capacitive plates 305a, 305b are electrically connected to the debris detection sensor 305 via suitable electrical connections. For example, the second capacitive plate 305b may be connected to the debris detection sensor 305 via an electrical lead running down one of the pins 312 (not shown).

Typically, each capacitive plate is coated in an insulating material. The insulating material can be any suitable material (e.g. a lacquer-like polymer such as epoxy). Polymers with high insulating properties are suitable, for example Polyoxymethylene, Polyurethane, Polystyrene, and a Polyimide like Kapton.

The length of the pins 312 is such that the magnet 314 and capacitive plate 305b projects within the gearbox casing and lubricating oil fills the space between the capacitive plates 305a, 305b. This is depicted schematically in Figure 4.

Ferrous debris present in the lubricating oil is attracted by the magnet and collects in the space between the two capacitive plates 305a and 305b. The capacitance of the capacitive plates 305a and 305b changes due to the presence of this debris which is detected by the debris detection sensor 305.

The debris detection sensor can be provided by any suitable capacitive sensor. In certain embodiments, an “off-the-shelf” sensor can be used. In other embodiments, a bespoke sensor can be provided comprising, for example, a temperaturecompensated capacitive network arranged in a Wheatstone-bridge configuration.

The amount of debris present between the capacitive plates 305a and 305b affects the magnitude of the capacitance measured across the plates. Typically, the sensor data signal generated by the debris detection sensor 305 and communicated to the processor corresponds to an instantaneous reading of the capacitance of the capacitive plates 305a, 305b.

Sudden changes in the capacitance of the capacitive plates 305a, 305b may be indicative of a safety critical fault with the gearbox (e.g. a gear wheel becoming damaged by losing a tooth or sustaining a crack or a bearing collapsing).

As described above, the processor is arranged to periodically activate the debris detection sensor 305. Typically, the length of time that the debris detector is activated for is selected to ensure that it is long enough for a reliable reading of the capacitance of the capacitive plates 305a, 305b to be taken whilst minimising the period of time that the sensor is activated and consuming power. Typically, the frequency with which the debris detection sensor 305 is activated is selected to ensure that changes in the capacitance (indicative of a potentially serious fault) are detected within an acceptable period of time.

In the embodiment depicted in Figure 3a, the capacitive plates are in a configuration in which they are parallel. However, other configurations of the capacitive plates are possible.

In one embodiment, depicted in Figure 3d the first and second capacitive plates 305a, 305b are positioned in a perpendicular arrangement where the second capacitive plate is substantially parallel to the pins 312.

In one embodiment, depicted in Figure 3e the first and second capacitive plates 305a, 305b are positioned in a parallel arrangement, where both capacitive plates are parallel to the pins and substantially perpendicular to the end of the inner cavity.

In certain embodiments, alternative types of sensors may be used to detect the presence of debris in the oil, for example a Hall effect sensor.

Returning to Figure 3a, the modified plug 301 includes a temperature sensor 306. The temperature sensor 306 is typically thermally coupled to the body 302 of the plug. By conduction, as the temperature of the oil in the gearbox changes, so too does the temperature to which the temperature sensor 306 is exposed. Thus, the sensor data signal from the temperature sensor 306 is indicative of the temperature of the oil in the gearbox.

Higher than expected temperatures may be indicative of a safety critical fault with the gearbox (e.g. a gear wheel becoming jammed). The temperature sensor can be provided by any suitable temperature sensor as is known in the art.

Upon activation, the temperature sensor 306 is typically arranged to measure the temperature to which it is exposed for a predetermined sample period. The predetermined sample period is chosen to ensure that a reliable temperature measurement can be taken, whilst minimising the period of time that the sensor is activated and consuming power from the power source 308.

The modified plug 301 includes a vibration sensor 307. As the modified plug 301 is mounted within the housing of the gearbox, vibrations occurring within the gearbox can be detected by the vibration sensor 307. The sensor data signal from the vibration sensor is indicative of vibrations to which the gearbox is exposed.

In certain examples, the sensor data signal generated by the vibration sensor 307 is indicative of the magnitude of the vibration that the plug is exposed to during a predetermined sample period. In certain embodiments, this is the “crest factor” - i.e. the ratio of the peak value of detected vibration during the sample period with the root mean square (RMS) value of the vibration. In certain embodiments, the RMS value is calculated as a “rolling average” of RMS values captured every time the vibration sensor is activated. The vibration sensor includes suitable signal processing electronics (for example an integrated circuit) which calculates the rolling RMS vibration value and monitors the peak value over the sample period and calculates and outputs a corresponding crest factor value. The signal processing electronics converts the crest factor value sensor data signal which is communicated to the processor.

The predetermined sample period is chosen to ensure that a reliable vibration measurement can be taken, whilst minimising the period of time that the sensor is activated and consuming power from the internal energy source. Advantageously, using the crest factor as a metric of vibration means that a single value can be used to determine vibration within the gearbox and unusual changes in vibration level can be readily detected. For example, higher than expected crest factor values may be indicative of a safety critical fault with the gearbox (e.g. a gear wheel becoming loose or another component within the gearbox becoming detached).

Any suitable sensor can be used for the vibration sensor. In certain examples a MEMS vibration sensor can be used.

As described above, the modified plug 301 includes a radio transmitter 310 arranged to transmit the wireless data signal containing the sensor data to an external wireless receiver. The radio transmitter can be provided by any suitable radio transmitting device arranged to communicate in accordance with predetermined wireless transmission protocols such as Zigbee or Bluetooth.

To enable the wireless data signal to be transmitted from the radio transmitter 310, the plug 301 includes an opening at the end of the head 303 which is sealed by a window 311 made from a radio-wave transparent material. Examples of such material include a suitable plastic (for example polytetrafluorethene (PTFE/Teflon), polyurethane, Neoprene (polychloroprene)) or strengthened glass.

The power source 308 is typically provided by a suitable battery, comprising for example one or more “button cell” batteries. In certain examples, the power source 308 is provided by a system that includes an energy harvesting mechanism, for example a mechanism that converts vibrations to which the plug is exposed in electrical energy used to charge a rechargeable battery.

In the embodiment described with reference to Figure 3a, the modified plug includes a sensor for detecting oil debris, a sensor for detecting temperature and a sensor for detecting vibration. In certain embodiments, further sensors can be included.

A modified plug in accordance with certain embodiments of the invention further includes a moisture detecting sensor. The sensor is adapted to detect the presence of moisture, for example water, within the oil. The presence of water in the oil could be indicative of the presence of a fault in the housing of the gearbox allowing water ingress. It will be understood that moisture, such as water, can be present in the oil in one of three states, namely dissolved, emulsified or “free”. Typically, the moisture detecting sensor is adapted to detect the presence of moisture such as water in any of these states or any combination of these states.

Figure 3f provides a schematic diagram depicting an example of a modified plug in accordance with certain embodiments of the invention including a moisture detection sensor 314. The moisture detection sensor 314 is connected, via a suitable connection (for example running through the inner cavity and partial along one of the pins), to an optical transmitter 315. The moisture detection sensor 314 is further connected, via a suitable connection, (for example running through the inner cavity and partial along one of the pins) to an optical detector 316. The optical transmitter 315 is controlled by the moisture detection sensor 314 to transmit an optical signal with a known optical frequency component which is received by the optical receiver 316. The optical receiver 316 is arranged to generate a signal which varies in dependence on the optical frequency components which it receives. This signal is communicated, via the connection, back to the moisture detection sensor. Changes in the water content of the oil will alter the frequency components of the optical signal received by the optical detector 316 (due to differences between the absorption of the optical signal in oil compared to oil contaminated with water).

The moisture detection sensor 314 generates sensor signal data indicative of the presence of moisture in the oil and communicates this to the processor. In keeping with the operation of the sensors described above, to conserve power, typically, the moisture detection sensor 314 is activated by the processor periodically for a period of time sufficient to acquire a reliable indication of the moisture content of the oil.

In certain embodiments, the moisture detection sensor 314 can also be used to infer information about the level of oil in the gearbox. That is, in certain embodiments, the moisture detection sensor 314 can also act as an oil level detecting sensor. Specifically, if there is an oil leak and the gearbox is partially or fully drained of oil, the absence of oil in the space between the optical transmitter 315 and optical receiver

316 will result in a change in the frequency components of the optical signal received by the optical receiver.

In certain embodiments, rather than using a moisture sensor based on optical transmission through the oil, instead other types of moisture detectors known in the art can be used. Examples include sensors that detect moisture by measuring changes in capacitance in the oil (for example a sensor incorporating a thin-film capacitor) or changes in resistance in the oil (for example a sensor incorporating means to measure the resistance across a given oil filled space).

In certain embodiments, a separate oil level detecting sensor can be provided.

In accordance with certain embodiments the oil plug includes a particle size sensor for detecting a particle size of debris within oil. Figure 3h provides a schematic diagram of such an arrangement. Specifically, a particle size sensor 317 is adapted to generate sensor data indicative of particle size of debris within the lubricating oil. The sensor includes an optical transmitter 317a and an optical receiver 317b in keeping, for example, with the moisture detector described above. The optical transmitter 317a is arranged to transmit an optical signal of constant intensity which is received by the optical receiver 317b. The optical receiver 317b is arranged to generate an output corresponding to the intensity of the received light from the optical transmitter. The sensor is adapted to monitor the intensity of the light received by the optical receiver 317b. Generally, the larger the particle size of the particle, the lower the intensity of the light received by the optical receiver 317b. The particle size sensor is adapted to generate sensor data indicative of an estimated particle size, typically, for example, an estimated average particle size.

In accordance with certain embodiments of the invention, an alternative particle sensor arrangement can be provided comprising a charge coupled device (CCD) imaging unit for capturing images of the oil. A schematic diagram of such an arrangement is shown in Figure 3i. The imaging unit 317c is positioned (for example mounted on one of the pins) and is adapted to capture images of the lubricating oil. In this embodiment, the particle size sensor 317 includes imaging processing functionality (for example a suitably programmed integrated circuit) arranged to receive image data from the CCD imaging unit 317c and to process the image data to identify particles in the oil and from the identified particles, the particle size sensor is adapted to generate sensor data indicative of an estimated particle size typically, for example, an estimated average particle size.

As described above, in certain embodiments, the processor receives the sensor data, stores it in the memory, and then controls the radio transmitter to transmit the wireless data signal containing the sensor data.

In accordance with certain embodiments of the invention modified plugs including different combinations of sensors are envisaged. For example, a modified plug including only a moisture detecting sensor and a vibration sensor; a modified plug including only a debris detection sensor and a temperature detection sensor and so on.

In certain embodiments, the processor is arranged to store the sensor data received from the sensors in the memory and transmit the wireless data signal including all the collected sensor data

In certain embodiments, the processor is arranged to process the sensor data before it is transmitted. In certain embodiments, the processor is arranged to process the sensor data from the sensors to determine if the sensor data is indicative of normal operation or if the sensor data is indicative of a potential fault with the gearbox. If the sensor data is indicative of normal operation (i.e. the sensor data from all the sensors is within an expected range), the processor controls the radio transmitter to transmit a wireless data signal with data simply indicating that no fault is detected and which includes no further sensor data.

However, if the sensor data is indicative of one or more of the sensors detecting a fault (e.g. a rapid change in the capacitance detected by the debris detection sensor or a rapid increase in temperature), the processor is adapted to control the radio transmitter to transmit the wireless data signal including an indication of the presence of a potential fault along, for example, with an indication of which sensor has detected the fault.

In certain embodiments, the processor is adapted to detect a fault by comparing the sensor data to predetermined values, and if the sensor data indicates that these predetermined values have been exceeded, a fault is detected. For example, stored in the memory may be data corresponding to a series of acceptable sensor data values. Alternatively, or additionally, the processor is adapted to detect the rate of change of the sensor data. That is, the processor is arranged to compare sensor data over a period of time to determine a rate of change in the measurement signals collected by a given sensor. If the rate of change exceeds a certain value (e.g. sensor data from the temperature sensor indicative of a rate of change of 10 degrees C over 10 minutes) then a fault is detected.

Typically, the wireless data signal transmitted from a plug also includes an identifier which uniquely identifies the plug. The wireless data signal may include further ancillary information, for example time stamp data indicating a time of transmission and, for example, a time at which sensor data was generated by the sensors.

Figure 3g provides a simplified schematic diagram of a further embodiment of the invention. The modified oil plug depicted in Figure 3g corresponds to that described with reference to Figure 3a, except that it further includes a first electrode 3001 and a second electrode 3002 for measuring an impedance of the oil across the gap between the capacitive plates. The first electrode 3001 and a second electrode 3002 are connected to the debris detection sensor via suitable connections (not shown). Impedance measurements generated in this way can be used to determine further information about the oil. Oil is typically a highly insulating fluid and therefore changes to the impedance can be indicative of small changes to the composition of the oil. The first and second electrodes 3001, 3002 are conveniently mounted on the capacitive plates. However, in certain embodiments, they can be mounted on other parts of the modified plug, for example on opposite pins 312 or on either side of one of the capacitive plates.

The system includes a train 501 which includes two carriages, each of which has two bogies 502a, 502b, 502c, 502d. Each bogey has a pair of driving wheels driven by a gearbox as described with reference to Figures 1 and 2. Each gearbox is fitted with a modified oil plug 503a, 503b, 503c, 503d as described above.

The train is further fitted with a train-mounted wireless transceiver unit 504. The wireless transceiver unit is arranged to receive the wireless data signals transmitted from each plug 503a, 503b, 503c, 503d.

The wireless transceiver unit 504 includes memory on which is stored data from the wireless data signals from the plugs.

The system further includes a second wireless transceiver unit 505, connected via a data network 506 to a data analysis system 507.

The train-mounted wireless transceiver unit 504 is arranged to periodically transmit the data received from the plugs to the second wireless transceiver unit 505.

On receipt of the data from the train-mounted wireless transceiver unit 504, it is communicated via the data network 506 to the data analysis system 507.

The data analysis system typically comprises a computing system, for example a server accessible via one or more terminals, and has running thereon software for processing data received from the plugs.

As described above, in certain embodiments, processing of the sensor data from the sensors of each plug is undertaken by the processor of the plug and the wireless data signal transmitted from the plug comprises an indication of a fault detected by a particular sensor. In such embodiments, the software running on the computing system is arranged to identify from the data received from the second wireless transceiver unit 505 that a fault has potentially been detected and to generate a corresponding alert.

In certain embodiments, this alert may be displayed on a user interface, displayed on a screen, monitored, for example, by an operative. In certain such embodiments, a displayed alert may comprise a display indicating on which train and in which gearbox of the train, the potential fault has been identified, along with an indication of the sensor-type (e.g. temperature sensor or vibration sensor) of the sensor on which the fault has been detected.

In certain embodiments, the data transmitted from each plug comprises the sensor data itself. In such embodiments, the software running on the computing system is arranged to process the sensor data from each plug to identify potential faults. In certain embodiments, the software maintains a data structure, comprising a number of normal operating data values indicative of normal operation of a gearbox. For example, a range of temperature readings, a range of vibration sensor crest factor readings and a range of capacitance readings collected from gearboxes known to be operating correctly. In the event that sensor data is received indicative of a sensor reading a predetermined amount outside this range of normal operating values, the software is arranged to generate an alert. In certain embodiments, the software is adapted to continuously or periodically update the normal operating values to take account of changes that might affect the operating conditions of the gearboxes, for example, changes in environmental temperature due to seasonal changes.

Figure 5 provides a simplified depiction of an example system. In certain embodiments, the data analysis system may be connected via a data network to multiple wireless transceiver units. The multiple wireless transceiver units may be conveniently distributed in static positions throughout a railway network, e.g. at predetermined locations next to the railway track (“track-side” locations), or at predetermined locations, such as stations or junctions, where trains may typically slow down or stop. In certain embodiments, the locations of such static wireless transceiver units are stored in the train-mounted wireless transceiver unit which is further equipped with position determining means (for example a global navigation satellite system, e.g. GPS receiver). In operation, such a train-mounted wireless transceiver unit is adapted to detect, via a GPS receiver that is within a predetermined proximity of such a static wireless transceiver and begin transmitting sensor data to be received by the static transceiver unit.

In certain embodiments the train-mounted wireless transceiver 504 is a wireless data transceiver capable of communicating data to and from a remote monitoring computing system via a cellular mobile telephone network and the wireless transceivers which receive data from the train-mounted wireless transceivers can be provided by the base stations of a cellular mobile telephone network. Such arrangements would not require dedicated “track-side” wireless transceivers for receiving data from the train-mounted wireless transceivers.

Data can be communicated from the train-mounted wireless transceiver 504 in any suitable way. As described above, in certain embodiments data is transmitted from the train-mounted transceiver 504 when it is determined that it in the proximity of a suitable receiver.

In other examples, for example when the wireless transceiver is provided by a wireless data transceiver capable of communicating data to and from a remote monitoring computing system via a cellular mobile telephone network, data may be transmitted from the wireless transceiver periodically (for example every 30 minutes, irrespective of location). In other examples, the data may be transmitted from the wireless data transceiver in response to a transmit data command communicated, for example, from the remote monitoring computing system via the cellular mobile telephone network. In yet further embodiments, data may be transmitted from the train-mounted wireless transceiver 504 only when a fault has been detected by a sensor in one of the plugs.

Further monitoring systems arrangements are envisaged. In certain embodiments, each plug is provided with a wireless data transceiver capable of communicating data to and from a remote monitoring computing system via a cellular mobile telephone network. Such arrangements would not require a train-mounted wireless transceiver 504 as depicted in the embodiment shown in Figure 5. In certain embodiments, processing of sensor data transmitted from each plug to identify potential faults can be undertaken by suitable processing means provided on a train-mounted processing unit, for example, which also incorporates the train-mounted wireless transceiver described above.

In certain embodiments, each plug includes a sounder arranged to generate an audible alarm in the event that a fault is detected.

In certain embodiments, a further alarm system is provided, comprising for example a sounder and/or light which is mounted within a train (for example within the driver’s cab) which includes gearboxes to which modified oil plugs, as described above, are fitted. In the event that a fault is detected, the sounder and/or light is activated. In certain embodiments, a signal to activate the alarm system is generated by the processor of a plug in which a fault has been detected and transmitted to a suitable receiver within the alarm system.

Embodiments of the invention have been described in terms of a modified oil plug which can be fitted to a gearbox of a train. However, oil plugs in accordance with embodiments of the invention can be used in other settings, specifically fitted to other oil-filled devices such as gearboxes used in other industrial gearboxes, such as gearboxes used in the marine, automotive, power generation (for example wind turbines) and mining industries, and in industrial pumps.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

It will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope being indicated by the following claims.

Claims

1. An oil plug for fitting to an oil-filled device and for monitoring operating conditions of the device, wherein said oil plug comprises:

one or more sensors, each sensor operable to detect an operating condition of the device and generate sensor data associated with the operating condition, and a wireless transmitter operable to transmit data associated with the sensor data to a receiver remote from the oil plug.

2. An oil plug for fitting to an oil-filled device, wherein one of the one or more sensors is an oil-debris detection sensor for detecting oil debris within oil of the oil filled device.

3. An oil plug according to claim 2, further comprising a magnetic part, proximate to the oil debris detection sensor, for attracting ferrous material.

4. An oil plug according to claim 2 or 3, wherein the oil-debris detection sensor is a capacitive sensor which detects oil debris by detecting changes in capacitance of the oil in the vicinity of the plug.

5. An oil plug according to claim 4, wherein the capacitive sensor comprises first and second capacitive plates separated by a gap open to ingress by the oil from the oil-filled device.

6. An oil plug according to claim 5, further comprising first and second electrodes for measuring an impedance of the oil across the gap.

7. An oil plug according to claim 6, wherein the first electrode is mounted on the first capacitive plate and the second electrode is mounted on the second capacitive plate.

8. An oil plug according to claim 2 or 3, wherein the oil-debris detection sensor is a Hall-effect sensor which detects oil debris by detecting changes in the magnetic field in the vicinity of the plug.

9. An oil plug according to any previous claim, wherein one of the one or more sensors is a temperature sensor for detecting a temperature of the oil-filled device.

10. An oil plug according to any previous claim, wherein one of the one or more sensors is a vibration sensor for detecting vibrations of the device.

11. An oil plug according to claim 10, wherein the sensor data from the vibration sensor comprises a crest factor value calculated as a ratio of the peak value of detected vibration during a sample period with the root mean square (RMS) value of the detected vibration during the sample period.

12. An oil plug according to any previous claim, wherein one of the one or more sensors is a moisture sensor for detecting moisture within the oil.

13. An oil plug according to any previous claim, wherein one of the one or more sensors is an oil level sensor for detecting an oil level within the device.

14. An oil plug according to any previous claim, wherein one of the one or more sensors is a particle size sensor for detecting a particle size of debris within oil of the device.

15. An oil plug according to claim 14, wherein the particle size sensor comprises a charge coupled device for capturing images of the oil.

16. An oil plug according to any of the preceding claims, further comprising a processor arranged to periodically activate the one or more sensors to detect the operating conditions and generate the sensor data.

17. An oil plug according to claim 16, further comprising a memory, said processor adapted to store the sensor data in the memory.

18. An oil plug according to claim 17, wherein the processor is operable to control the wireless transmitter unit to periodically transmit the sensor data stored in the memory to the remote receiver.

19. An oil plug according to claim 18, wherein the processor is operable to control the wireless transmitter to transmit the sensor data at predetermined time intervals.

20. An oil plug according to any previous claim, wherein the sensors and the wireless transmitter are substantially entirely enclosed within a body of the oil plug.

21. An oil plug according to any previous claim, further comprising an opening sealed by a window transparent to radio signals transmitted from the wireless transmitter.

22. An oil plug according to any previous claim, wherein the oil plug has a formfactor substantially corresponding to a conventional oil plug for the device.

23. An oil plug according to any previous claim, comprising a threaded body and a head.

24. An oil plug according to any of claims 16 to 23, wherein the processor is adapted to control the wireless transmitter to transmit identification data for identifying the oil plug.

25. An oil plug according to any previous claim, wherein the device is an oil-filled gearbox.

26. An oil plug according to claim 25, wherein the gearbox is a railway train gearbox.

27. An oil plug according to any previous claim, wherein the device is a pump.

28. A remote monitoring system comprising one or more wireless transceivers and a data analysis system, said wireless transceivers operable to receive sensor data from one or more oil plugs according to any of claims 1 to 27 and communicate said sensor data to the data analysis system, wherein said data analysis system is operable to process the sensor data to identify sensor data indicative of abnormal gearbox operation and responsive to identifying sensor data indicative of abnormal gearbox 5 operation, generate an alert.