Lubricant debris monitoring system for gas turbine engine

There is disclosed a lubricant debris monitoring system for a gas turbine engine. The system includes a magnetic chip collector having electrodes defining a gap therebetween configured to be filled with lubricant. The magnetic chip collector generates a magnetic field for attracting the debris. The system further includes a processor configured to be connected to a power source and for performing an analysis of an signal between the electrodes. The processor stores occurrences of at least one characteristic of the signal exceeding a respective threshold. The system further has a communication system communicatively connected to the processor and configured for transmitting the analysis of the signal.

TECHNICAL FIELD

The application relates generally to gas turbine engines and, more particularly, to systems and methods used to detect debris within a lubrication system of such engines.

BACKGROUND OF THE ART

Rotating components of gas turbine engines are typically operatively connected to a lubrication system for proper lubrication. With use, the rotating components may wear. Therefore, residue or debris coming from these components may circulate within a lubricant of the lubrication system. Proper operation of the rotating components may be impaired if a concentration, or level, of such debris reaches a given threshold. Moreover, the level of such debris may be indicative of a deterioration of one of the rotating components. Therefore, systems are used to collect said debris. However, many engines and aircraft are only equipped with chip collectors that trap the debris without providing any feedback regarding the level of debris. Periodic maintenance for verifying a state of the chip collector, which are typically very time-consuming, have to be scheduled.

SUMMARY

In one aspect, there is provided a lubricant debris monitoring system for a gas turbine engine, comprising: a magnetic chip collector operatively coupled to a lubrication system, the magnetic chip collector having electrodes defining a gap therebetween, the gap exposed to lubricant of the lubrication system, the magnetic chip collector in use generating a magnetic field for attracting the debris toward the electrodes, the magnetic chip collector configured to generate a signal when a metal chip in the lubricant bridges the gap and allows connection of the electrodes; a processor operatively connected to the electrodes of the magnetic chip collector and connected to a power source, the processor configured for performing an analysis of the signal for detecting occurrences of at least one characteristic of the signal exceeding a respective threshold and for storing the analysis with the occurrences; and a communication system communicatively connected to the processor and configured for transmitting the analysis of the signal.

In another aspect, there is provided a gas turbine engine comprising a lubrication system for lubricating rotating components of the gas turbine engine, the lubrication system having a fluid circuitry operatively connected to the rotating components and configured for circulating a lubricant; the gas turbine engine further having a lubricant debris monitoring system operatively coupled to the lubrication system, the lubricant debris monitoring system having a magnetic chip collector coupled to the lubrication system and having electrodes defining a gap therebetween, the gap exposed to the lubricant, the magnetic chip collector in use generating a magnetic field for attracting the debris toward the electrodes, the magnetic chip collector configured to generate a signal when a metal chip in the lubricant bridges the gap and allows connection of the electrodes; a processor operatively connected to the electrodes and to a power source, the processor configured for performing an analysis of a signal between the electrodes for detecting occurrences of at least one characteristic of the signal exceeding a respective threshold and for storing the analysis with the occurrences; and a communication system communicatively connected to the processor and configured for transmitting the analysis of the signal.

In yet another aspect, there is provided a method of operating a lubricant debris monitoring system of a gas turbine engine, comprising: attracting debris circulating within a lubricant of a lubrication system toward electrodes of a magnetic chip detector, a signal between the electrodes being affected by the debris located within a gap between the electrodes; performing an analysis of the signal between the electrodes to detect occurrences of at least one characteristic of the signal exceeding a respective threshold; storing the analysis with the occurrences; and transmitting the analysis of the signal.

DETAILED DESCRIPTION

FIG. 1illustrates a gas turbine engine10of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a propeller12through which ambient air is propelled, a compressor section14for pressurizing the air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. The engine10further includes an engine controller20for controlling flight parameters of the gas turbine engine10. The flight parameters may be, for instance, fuel flow regulation, thrust management, and actuation of valves and pumps required for proper operation of the engine10.

The engine10further includes a lubrication system22operatively connected to a rotating component24, which may be, for instance, a gearbox24of the engine10. The lubrication system22includes a fluid circuitry26circulating a lubricant in and out of the gearbox24. In the embodiment shown, a pump28is used for circulating the lubricant within the fluid circuitry26.

The engine10includes a lubricant debris monitoring system30operatively connected to the lubrication system22. The lubricant debris monitoring system30may be connected for example to the fluid circuitry26of the lubrication system22. The lubricant debris monitoring system30may be configured for collecting debris within the lubricant and for collecting data about a level of debris within the lubricant.

Referring now toFIGS. 2 and 3, a schematic view of the lubricant debris monitoring system30in accordance with one embodiment is illustrated. The lubricant debris monitoring system30includes a sensor32configured for being exposed to the lubricant and for detecting debris within the lubricant, and a data module34operatively connected to the sensor32. A power source36is used for powering the sensor32and the data module34. The power source36may be either dedicated to the lubricant debris monitoring system30or be an external power source such as a generator of the gas turbine engine10or an electrical system of an aircraft. In the embodiment shown, an electric circuit38electrically connects by wires40the power source36to the sensor32and to the data module34via methods known in the art.

In the embodiment shown, the sensor32has two electrodes32a,32bthat are spaced apart from each other by a gap44. The gap44is configured to be filled with the lubricant. The two electrodes32a,32bare suitably electrically connected to the electric circuit38and bathe in the lubricant. For example, the electrodes32a,32bextend through a flow path46of the lubricant within the fluid circuitry26of the lubrication system22. In another embodiment, the electrodes32a,32bare in a reservoir of the lubrication system22. The two electrodes32a,32bare submerged in the lubricant (e.g., within the flow path46) and are used to determine the presence of debris therein. More details about this aspect are presented herein below.

In the embodiment shown, the lubricant debris monitoring system30is independent from the engine10, i.e., it is a self-contained system. The data module34is configured to transmit the data regarding the level of debris to a third party48without interference with the engine controller20(FIG. 1), i.e., without the engine controller20being a compulsory intermediate. A communication link50is established between the data module34and the third party48. The communication link50bypasses the engine controller20. Stated otherwise, the lubricant debris monitoring system30does not require the engine controller20, or any other system of the aircraft equipped with the engine10, for communicating and transferring its data to the third party48. The engine controller20may wirelessly communicate with a cockpit of the aircraft equipped with the engine10. In such a case, a communication link established between the engine controller20and the cockpit is parallel to, and separate from, the communication link50between the lubricant debris monitoring system30and the third party48. In the embodiment shown, the third party48is a smartphone, a PDA, or any other suitable device. The communication link50may in an embodiment be bi-lateral.

The lubricant debris monitoring system30as discussed above can be achieved with the exemplary features illustrated inFIG. 3. According to the illustrated embodiment, the sensor32, the data module34, and the power source36are mounted on a common device, such as plug100. In a particular embodiment, the plug100is totally independent from the engine10as it is self-powered. Hence, the plug100may be a self-contained device for the detection of debris within the lubricant. This aspect is described herein below.

In the embodiment shown, the plug includes a threaded portion100aconfigured for engaging a corresponding threaded aperture52defined through a wall26aof the lubrication system22. By inserting the threaded portion100ain the threaded aperture52, the two electrodes32a,32bextend into the lubricant and are in contact with the lubricant. The plug100may or may not include a tool receiving portion100bconfigured for being engaged by a wrench for screwing the plug100within the corresponding threaded aperture52. As shown, the tool receiving portion100bhas a shape of an hexagonal nut. The data module34may be located within or mounted to an external portion100cof the plug100that is configured to remain exposed to air of an environment E outside the flow path46.

For being autonomous, the power source36may be an energy harvesting device D such as, in the embodiment shown, a thermoelectric generator54. The thermoelectric generator54includes a cold probe54aand a hot probe54b. The hot probe54bextends through the threaded portion100aof the plug100such that it extends into the lubricant to be in contact therewith whereas the cold probe54aextends through the external portion100csuch that is it exposed to the environment E outside of the flow path46to be in contact with air of the environment E. The thermoelectric generator54is configured to generate electricity from a temperature difference between the lubricant and air of the environment E outside the lubrication system22. Any suitable thermoelectric generator54known in the art may be used. A battery may be required to store energy generated by the thermoelectric generator54. Alternately, the power source36may be a battery, or may be a connection to an electrical system of the gas turbine engine10or of the aircraft. In a particular embodiment, by generating its own power, the lubricant debris monitoring system30is totally autonomous from the engine10. The energy harvesting device D is configured for powering all functions of the data module34. The latter includes components for data acquisition. Alternately, photoelectric cells (e.g., solar cell) may be used to power the debris monitoring system30. The photoelectric cells may be affixed to an exterior of the engine10to be exposed to solar radiation. A battery may be used for storing the energy from the cell.

In the embodiment shown, the data module34includes a computer readable medium34aand a processor34bcommunicatively connected to the computer readable medium34a. Any suitable processor and computer readable medium may be used. The computer readable medium may be a computer readable memory having recorded thereon statements and instructions for execution by the processor, in accordance with the method described below. The computer readable medium34ais configured for storing the data regarding the level of debris in the lubricant. The processor34bis configured for interpreting signals from the sensor32and for writing the data on the computer readable medium34a.

In the embodiment shown, the sensor32may further include a magnetic chip collector32′ generating a magnetic field for attracting the debris. In the embodiment shown, at least one of the two electrodes32a,32bis magnetic for attracting the debris. In the embodiment shown, when an amount of debris collected by the magnetic chip collector32′ via the magnetic electrode32ais below a given threshold, the electric circuit38(FIG. 2) is opened between the two electrodes32a,32bsuch that no electrical communication is possible between the two electrodes32a,32bvia the gap44. With time, the magnetic electrode32acumulates debris thereon such that the gap44between the two electrodes32a,32bis gradually bridged by debris. The given threshold may correspond to an amount of debris required to bridge the gap44. When the gap44is bridged, the electric circuit38becomes closed and current may circulate from one of the two electrodes32a,32bto the other via the bridged gap44. The data module34via its processor34b, which is operatively connected to the electrodes32a,32band to the power source36, is configured for performing an analysis of an electrical signal between the electrodes32a,32band for storing occurrences of at least one characteristic of the electrical signal exceeding a respective threshold. The analysis may be stored on the computer readable medium or elsewhere (e.g., cloud).

More specifically, a quantity of the debris within the gap44varies an electrical resistance between the electrodes32a,32b. As the current varies inversely to the electrical resistance, by varying the quantity of the debris bridging the gap44the electrical resistance between the electrodes32a,32bvaries and a magnitude of the current between the electrodes varies.

Therefore, the characteristics of the electrical signal may be a magnitude of a current between the electrodes, a duration of a period during which the magnitude of the current remains beyond a current threshold, and/or a frequency of occurrences where the magnitude of the current exceeds the current threshold. For the duration of the period, the threshold is a duration threshold expressed in a unit of time. For the frequency of occurrences, the threshold is a frequency threshold expressed in a number of occurrences over a unit of time (e.g., number of occurrences per minute).

In the embodiment shown, the lubricant debris monitoring system30allows continuous monitoring of the electric signal between the electrodes32a,32band thus of a level of debris captured by the magnetic chip collector32.

The data/analysis stored on the computer readable medium34ais accessible to the third party48for inspection by a user. In the embodiment shown, this accessibility of the data regarding the analysis to the third party48is provided by a communication system34cof the data module34. The communication system is communicatively connected to the processor34band configured for transmitting the analysis of the electrical signal. The communication system34cmay be a receiver/transmitter for secure bidirectional communication with the third party48, so as to accept commands from the third party48(e.g., reset, uploads, etc). In contrast, the communication system34cmay be limited to uni-directional communication with the engine controller20, for example to inform an operator of excess debris in the lubricant, and the requirement for maintenance. The communication standards may for instance be Bluetooth® or wifi. The communication system34cmay be communicatively separated from the engine controller20. As illustrated, the communication system34cincludes electronic components34c1operatively connected to a wireless antenna34c2by suitable means such as wires34d. The communication system34cis communicatively connected to the processor34bby wires34ffor transferring the data from the computer readable medium34ato the electronic components34c1of the communication system34cand hence to the third party48via the wireless antenna34c2.

In the embodiment shown, the lubricant debris monitoring system30allows the detection of transient chips. Transient chips are debris that momentarily get trapped by a magnetic field of the magnetic electrode32aso that they bridge the gap44between the two electrodes32a,32bof the magnetic chip collector32′, thereby closing the circuit38, but that do not remain attached to the collector32′. The transient chips may be dislodged by, for instance, the flow of lubricant circulating in the flow path46around the transient chips. The transient chips, which are momentarily trapped by the magnetic field, induce fluctuations of at least one of the characteristics of the signal that are discussed herein above. Stated otherwise, the transient chips may cause the magnitude of the current between the two electrodes to exceed the current threshold during a certain period of time. Stated otherwise, a transient chip may decrease an electrical resistance between the electrodes32a,32band allow circulation of a current that is greater in magnitude than that of a current passing between the electrodes without the transient chip.

In the embodiment shown, the processor34bmay write on the computer readable medium34athat, at some point, the gap44was bridged. In a particular embodiment, this is advantageous as it allows a user to notice that, although the gap44might not be bridged at the time of inspection, the gap44was bridged at some point. Hence, this might offer advanced warning that the gap44is close to be bridged. This might offer an earlier notification regarding components deterioration (e.g., the gearbox24) compared to an existing chip collector that simply collects the chip and requires a visual inspection to determine the level of debris within the lubricant.

Previous collectors require a maintenance technician to open cowls of the engine10to access a magnetic chip collector periodically at intervals, such as from six to twelve months, or every fifty hours of flight. Such a procedure may be expensive and time consuming. Moreover, installing a device to actively monitor the level of debris within the lubricant typically requires wirings to connect the device to a cockpit annunciator. This is a cumbersome task and adds weight to the aircraft. In some cases, such a modification is not possible for all engines.

In a particular embodiment, the above described features of the lubricant debris monitoring system30allows its installation in an engine that has not been initially configured for actively monitoring its lubrication system22. Hence, in a particular embodiment, installation of the lubricant debris monitoring system30does not require any wire, any modification of the cockpit, and does not require electricity from the engine10or aircraft.

In a particular embodiment, by being self-contained, the lubricant debris monitoring system30allows the pilot or the maintenance technician to monitor the lubrication system22for presence of magnetic particles on demand using the third party48(FIG. 2) (e.g., PDA device, smartphone application). Hence, the lubricant debris monitoring system30, which might enhance safety and reduce engine repair costs, might be available to operators of all turbine powered aircraft. In such a case, the data module34may provide its identity to the third party40, for identification of the aircraft. In a particular embodiment, the lubricant debris monitoring system30might be used for retrofitting aircraft/engines that do not have debris monitoring capabilities. Moreover, the periodic maintenances might not be required.

In a particular embodiment, the sensor32is configured for monitoring a magnitude of an electric conductivity of the lubricant between its two electrodes32a,32bvia the gap44. The electric conductivity of the lubricant might be altered by the presence of the debris therein. For instance, the electric conductivity might increase if the electric conductivity of the debris is greater than that of the lubricant free of debris. In this particular embodiment, the lubricant debris monitoring system30is configured for continuously monitoring the electric conductivity of the lubricant. For example, the system30might be configured for measuring the conductivity at regular time intervals and storing the measured conductivity within the computer readable medium34a. The user (e.g., pilot, maintenance technician), via the third party48, may then review the data that would represent an evolution in time of the conductivity of the lubricant. The lubricant debris monitoring system30might be configured for sending a notification to the third party48when the conductivity reaches a predetermined threshold that is indicative of component deterioration. The system30might be configured to measure a resistance encountered by a current circulating between two electrodes that varies with the presence of the debris in the lubricant. In a particular embodiment, the sensor32is configurable to set the predetermined threshold of the resistance or of the conductivity.

In a particular embodiment, the debris monitoring system30may be configured to measure a temperature and a pressure of the lubricant within the lubrication system22. This might be achieved by incorporating a thermocouple and/or a piezoelectric transducer in the system30. The system30may hence be configured for storing and analysing data regarding the pressure and/or the temperature of the lubricant. This might allow for the detection of a deterioration in the seals that control ingress of air in to the lubrication system22.

In a particular embodiment, the sensor32may include a sensor coil wrapped around a conduit of the lubrication system22circulating the lubricant. The sensor coil is configured for receiving a current generating a magnetic field attracting the debris. The sensor32may be configured for measuring variations of the magnetic field as the result of the passage of the debris within the conduit. In such a case, the sensor measures a variation with time of the magnetic field which may offer information regarding the level of debris within the lubricant. In this particular embodiment, data about the size of the debris may also be measured. These data may be derived from an amplitude and/or a phase of an output signal from the sensor coil.

Referring toFIGS. 1-3, for operating the lubricant debris monitoring system30, the debris circulating within the lubricant of the lubrication system22are attracted toward the electrodes32a,32bof the magnetic chip collector32′. The electrical signal between the electrodes32a,32bis analyzed. The electric signal is affected by the debris located within the gap44between the electrodes32a,32b. Occurrences of at least one of the characteristics of the electrical signal exceeding a respective threshold are stored. The analysis of the electrical signal is then transmitted. The analysis may be wirelessly transmitted and may be transmitted by establishing the communication link from the debris monitoring system30. In the embodiment shown, the communication link bypasses the engine controller20of the gas turbine engine10.

As illustrated, storing the occurrences of the characteristic includes storing the occurrences of at least one of a magnitude of a current between the electrodes exceeding a current threshold, a duration of a period during which the magnitude of the current remains beyond the current threshold exceeding a duration threshold, and a frequency of occurrences where the magnitude of the current exceeds the current threshold exceeding a frequency threshold.

In the embodiment shown, the lubricant debris monitoring system30further alerts a user (e.g., maintenance crew, pilot) that an impending maintenance action of the gas turbine engine is required when at least one of the characteristics of the signal exceeds its respective threshold. As aforementioned, the transient chips within the lubricant cause the characteristics of the signal to vary. When too much transient chips are present within the lubricant, the user may be notified that maintenance of the gas turbine engine is required because the presence of these chips might be caused by components deterioration and might be indicative of an impending failure of said components. In the embodiment shown, power for powering the lubricant debris monitoring system30is generated. As shown, the power is generated by converting in electricity a temperature difference between the lubricant and air of the environment E outside the lubricant.

The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For instance, it is understood that the disclosed system may be used to monitor lubricant of other types of engines (e.g., piston engines, steam turbines) and/or of other components (e.g., gearboxes). Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.