SYSTEMS AND METHODS FOR POWER ASSEMBLY DIAGNOSTICS

BACKGROUND

[0001] The disclosure relates generally to an engine system and more specifically to systems and methods for detecting anomalies in a power assembly of the engine system.

[0002] Typically, locomotives use engines to generate necessary driving power to overcome resistive loads on the locomotives. These engines may be internal combustion engines, such as two-stroke engines, four-stroke engines, gas engine or diesel engines. Further, the engines may include one or more cylinders depending upon the driving power required for the locomotive. Each of the cylinders may include a power assembly, a turbo charger, an evacuation system, and a cooling system. The power assembly may generally include at least two valves, one cylinder head, cylinder liner, and piston. During the operational life of the engine, one or more faults may occur in the power assembly. Some of the faults may include liner wear, piston ring failure, misfire, scuffing, bore distortion, lubrication friction between the piston and the cylinder, and/or valve defects. Also, these faults may cause an increased blow-by of exhaust gases into a crankcase of the engine leading to a crankcase over pressure (CCOP). In addition, the CCOP in the engine may degrade the performance of the engine, thereby causing economic loss to a user. Thus, it is desirable to detect these faults in the power assembly at an incipient stage to increase the life of the engine and also to substantially reduce maintenance cost of the engine.

[0003] Conventionally, the faults in the power assembly are manually diagnosed by cutting fuel supply to the cylinders either manually or automatically via the engine control unit (ECU) and monitoring acoustic sounds that are produced in the engine. However, the acoustic sounds may be contaminated by noise. Also, manually separating this noise from condition monitoring information may be difficult. Consequently, these conventional techniques may fail to accurately detect faults in the engine. Also, these methods may not provide enough resolution to impact the case cycle time or turnaround time in a service shop.

[0004] Further, other techniques, such as vibration and airborne acoustic techniques may be employed to diagnose faults in the engines. Unfortunately, vibration monitoring techniques provide only limited information about engine conditions. Also, these techniques may entail use of many accelerometers and different measurement positions to achieve a general estimation of the engine condition. Another disadvantage is that the vibration signals are contaminated by noise and therefore entail use of effective signal processing to obtain useful information. Problems also arise due to the non-stationary characteristics of the vibration signals encountered in the engine. Airborne acoustic signals may provide relatively more information about the engine. However, these acoustic signals are easily contaminated by noise, and hence extracting useful condition monitoring information from these acoustic signals is a laborious process.

BRIEF DESCRIPTION

[0005J Briefly in accordance with one aspect of the present disclosure, a device for monitoring a power assembly of an engine subsystem is presented. The device includes at least one acoustic emission sensor operatively coupled to at least one cylinder in the power assembly and configured to sense an acoustic emission signal corresponding to the at least one cylinder. The device further includes a pressure sensor operatively coupled to the at least one cylinder and configured to sense a pressure signal corresponding to the at least one cylinder. Also, the device includes a processing module operatively coupled to the at least one acoustic emission sensor and the pressure sensor and configured to determine event data of the at least one cylinder based on the acoustic emission signal and the pressure signal and detect an anomaly in the at least one cylinder based on the determined event data.

[0006] In accordance with a further aspect of the present disclosure, a method for detecting an anomaly in a power assembly is presented. The method includes sensing an acoustic emission signal corresponding to at least one cylinder in the power assembly. The method further includes detecting a pressure signal corresponding to the at least one cylinder. Also, the method includes determining event data corresponding to the at least one cylinder based on the acoustic emission signal and the pressure signal. Furthermore, the method includes detecting the anomaly in the power assembly by comparing the determined event data with reference event data.

[0007] In accordance with another aspect of the present disclosure, a diagnostic kit is presented. The diagnostic kit includes at least one acoustic emission sensor operatively coupled to at least one cylinder in a power assembly and configured to sense an acoustic emission signal corresponding to the at least one cylinder. Further, the diagnostic kit includes a pressure sensor operatively coupled to the at least one cylinder and configured to sense a pressure signal corresponding to the at least one cylinder. Also, the diagnostic kit includes a processing module operatively coupled to the at least one acoustic emission sensor and the pressure sensor and configured to detect an anomaly in the at least one cylinder based on the acoustic emission signal and the pressure signal corresponding to the at least one cylinder.

DRAWINGS

[0008] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0009] FIG. 1 is a block diagram of a diagnostic system, in accordance with aspects of the present disclosure;

[0010] FIG. 2 is a flow chart illustrating a method for detecting anomalies in a power assembly, in accordance with aspects of the present disclosure;

[0011] FIG. 3 is a graphical representation of an acoustic emission signal, in accordance with aspects of the present disclosure;

[0012] FIG. 4 is a graphical representation of acoustic emission signals corresponding to different cycles, in accordance with aspects of the present disclosure;

[0013] FIG. 5 is a graphical representation of acoustic emission signals, in accordance with aspects of the present disclosure; and

[0014] FIG. 6 is a graphical representation of a pressure signal superimposed on the acoustic emission signals, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

[0015] As will be described in detail hereinafter, various embodiments of an exemplary diagnostic device for detecting anomalies in a power assembly of an engine system and a method for detecting anomalies in the power assembly are presented. By employing the methods and the various embodiments of the diagnostic device described hereinafter, anomalies or defects in the engine system may be easily detected, thereby reducing cost for replacing the engine system or components in the engine system.

[0016] Turning now to the drawings, and referring to FIG. 1, a block diagram of a diagnostic system 100, in accordance with aspects of the present disclosure, is depicted. The diagnostic system 100 may include an anomaly detection module (ADM) 102 that is configured to detect any anomalies in an engine subsystem 104. In one embodiment, the ADM 102 is operationally coupled to the engine subsystem 104. The engine subsystem 104 may be used as a power source in a locomotive or any vehicle. More specifically, the engine subsystem 104 may be used to generate driving power to overcome resistive loads on the locomotive. Also, the engine subsystem 104 may be any type of internal combustion engines. Moreover, the engine subsystem 104 may include one or more bays with a set of cylinders in each bay.

[0017] In the embodiment of FIG. 1, the engine subsystem 104 may be a diesel engine that includes a left bay 126 and a right bay 128. Further, each bay may include a plurality of cylinders that are mechanically coupled to a crank 130 of the engine subsystem 104 via a piston. For example, the engine subsystem 104 may be a 12 cylinder, 4 stroke medium speed high power diesel engine. In the embodiment of FIG. 2, each bay 126, 128 is shown as including six cylinders. Moreover, each of the cylinders 132, 134 in the engine subsystem 104 may have at least two valves, one cylinder head, cylinder liner, and a piston. These components may collectively be referred to as a power assembly 106 of the cylinder. It may be noted that each cylinder may have its own corresponding power assembly. In addition, each of the cylinders may include a decompression valve 110 that is used to remove trapped gases from the cylinders.

[0018] Further, the engine subsystem 104 may include an engine control unit 108 that is operatively coupled to the crank 130 of the engine subsystem 104. The engine control unit 108 may be configured to receive diagnostic and sensor data from the crank 130 and/or other components of the engine subsystem 104. This diagnostic and sensor data may include at least a rotational speed of the crank 130, a turbo charger speed, and pressures and temperatures at various stages of the engine subsystem 104. It may be noted that the engine subsystem 104 may include other components that may help in functioning of the engine subsystem 104.

[0019] During operation, one or more faults/anomalies may occur in the power assembly 106 of the engine subsystem 104. In general, the anomalies in the power assembly 106 may include fuel injector failure, cylinder head cracks, piston top land cracks, piston crown cracks, liner wear, piston ring failure, misfire, scuffing, bore distortion, lubrication friction between the piston and cylinder, valve defects, bent con rod, big end and small end bushing wear, and the like. These defects may manifest as combustion noise and/or mechanical noise in at least one cylinder in the power assembly 106. Also, these defects may cause increased temperature and/or decreased peak cylinder pressure in at least one cylinder in the power assembly 106. Some of these faults may result in an increased blow-by of exhaust gases into a crank case of the engine subsystem 104 leading to a crankcase over pressure (CCOP). The CCOP is frequently related to hard failures, such as road failures of the locomotive, and entails highest cost in terms of downtime for the customer, towing, and haulage costs in addition to part replacement cost. Moreover, this CCOP in the engine subsystem 104 may degrade the performance of the engine subsystem 104.

[0020] To address these problems, in accordance with aspects of the present disclosure, the anomaly detection module (ADM) 102 may be operationally coupled to the engine subsystem 104 to detect anomalies in the engine subsystem 104. In the present example, the engine subsystem 104 may be disposed in a medium speed high power engine/locomotive. The ADM 102 may be configured to acquire data for a relatively short duration when the locomotive is disposed on the service track. Further, the ADM 102 may be configured to process the acquired data to determine any anomalies in the engine subsystem 104. Also, upon acquiring the data, the ADM 102 may be decoupled from the locomotive/engine. Moreover, in one embodiment, the ADM 102 may be a high speed module that is configured to acquire data at a rate of about 2 MHz within a time period of about 1 minute.

[0021] In accordance with aspects of the present disclosure, the ADM 102 may include one or more acoustic emission (AE) sensors 112, 114 and a pressure sensor 116. The AE sensors 112, 114 may be configured to determine AE signals that are associated with stress waves propagating in the engine subsystem 104. In a similar manner, the pressure sensor 116 may be configured to determine a pressure signal that is associated with in-built pressure of at least one of the cylinders. Particularly, the AE sensors 112, 114 may be coupled to at least one cylinder in the engine subsystem 104. For example, a first AE sensor 112 may be coupled to one of the cylinders in the left bay 126 of the engine subsystem 104 to sense an AE signal corresponding to the left bay 126 of the engine subsystem 104. Similarly, a second AE sensor 114 may be coupled to one of the cylinders in the right bay 128 of the engine subsystem 104 to sense an AE signal corresponding to the right bay 128 of the engine subsystem 104. Moreover, the first AE sensor 112 and the second AE sensor 114 may operate in a frequency range from about 25 KHz to about 1 MHz, in one example.

[0022] Also, the pressure sensor 116 may be coupled to at least one of the cylinders in the left bay 126 and/or the right bay 128 of the engine subsystem 104. More specifically, in one embodiment, the pressure sensor 116 may be coupled to a decompression valve 110 of the cylinder. In one example, the pressure sensor 116 may be coupled to the decompression valve 110 corresponding to those cylinders that are operatively coupled to one of the AE sensors 112, 114. For example, if the first AE sensor 112 is coupled to a first cylinder Ci in the left bay 126 and the second AE sensor 114 is coupled to a third cylinder C3 in the right bay 128, then the pressure sensor 116 may be coupled either to the first cylinder C| in the left bay 126 or to the third cylinder C3 in the right bay 128 of the engine subsystem 104.

[0023] In addition, the pressure sensor 116 may be used to identify a peak pressure of the cylinder. Magnitude of the peak pressure may be indicative that the combustion of fuel has occurred in that cylinder. The event corresponding to the combustion of fuel in the cylinder is generally referred to as a combustion event. Also, an angle of the crank 130 at which this combustion event occurs in the cylinder is referred to as a firing angle. Furthermore, the identified peak pressure of the cylinder may also be used for diagnosing dead cylinders in the engine subsystem 104. The dead cylinders may be representative of cylinders that do not generate power when faults occur in the engine subsystem 104.

[0024] Moreover, the ADM 102 may include one or more preamplifiers that are used to amplify the AE signals received from the corresponding AE sensors 112, 114. Also, in one example, a first preamplifier 118 may be coupled to the first AE sensor 112, while a second preamplifier 120 may be coupled to the second AE sensor 114. The AE signals received from the AE sensors 112, 114 may include data corresponding to stress waves in the cylinders. In accordance with aspects of the present disclosure, these stress waves may be used to detect faults in the cylinders. For example, cracks in the piston ring or cylinder liner may generate a creaking sound in the cylinder. This creaking sound may propagate as stress waves across the cylinders. The stress waves may have a frequency in a range from about 25 KHz to about 1 MHz. Also, these stress waves may be dampened while propagating across the cylinders in a bay. Consequently, it may be difficult to accurately sense and process this dampened AE signal. To alleviate problems associated with poor signal strength, the preamplifiers 118, 120 are employed in association with the AE sensors 112, 114 to enhance the signal strength of the received AE signals.

[0025] In accordance with aspects of the present disclosure, the ADM 102 may also include a processing module 122. In a presently contemplated configuration, the processing module 122 may be coupled to the preamplifiers 118, 120, the pressure sensor 116, and a display unit 124. Also, the processing module 122 may be configured to determine anomalies in the power assembly 106 based on the AE signals and the pressure signal. Particularly, the processing module 122 may be configured to receive the AE signals from the preamplifiers 118, 120 and the pressure signal from the pressure sensor 116. In addition, the processing module 122 may also be configured to receive rotational speed of the crank 130 from the engine control unit 108 of the engine subsystem 104. Further, the processing module 122 may be configured to convert the received AE signals and the pressure signal from a time domain to a crank angle domain based on the received rotational speed of the crank 130.

[0026] Thereafter, the converted AE signals and the pressure signal may be compared with a reference event map to identify events occurring in each of the cylinders. The events may include an inlet valve open event, an outlet valve close event, the combustion event, an inlet valve close event, and an outlet valve open event of the cylinder. The reference event map is representative of various events that occur in the engine subsystem 104 at a corresponding crank angle. Moreover, the reference event map of a particular engine subsystem may be previously determined and/or created based on the firing order of the cylinders and the crank angle corresponding to the inlet valve opening, the inlet valve closing, the fuel injection, the exhaust valve opening, and the exhaust valve closing of the cylinders in the corresponding engine subsystem.

[0027] The reference event map may include data associated with one or more events corresponding to one or more cylinders in the engine subsystem 104. Hence, the reference event map may be employed to identify events in the cylinders. In one example, the converted AE signals and the pressure signal may be compared with the reference event map to aid in the identification of the events. Particularly, the converted AE and pressure signals may be superimposed on the reference event map to identify the events in the one or more cylinders. The pressure signal may be used as a reference signal to process the AE signals to identify events in a corresponding cylinder.

[0028] Furthermore, in one embodiment, the identified events may be compared with events data of the reference event map to aid in the detection of the anomalies in at least one cylinder of the engine subsystem 104. The presence of defects or anomalies in the power assembly 106 results in a change in the magnitude and/or the fundamental frequency of the AE signals corresponding to the events. This change in the magnitude and/or the fundamental frequency of the AE signals may be easily identified when compared with the reference event map. Particularly, the processing module 122 may be configured to identify at least one parameter associated with one or more events in the cylinder. This parameter may include peak amplitude, rise time, time duration, root mean square (RMS) voltage, signal strength, energy, and the like. Further, the processing module 122 may be configured to compare the identified parameter with the reference event data to detect anomalies in the cylinder. It may be noted that the processing module 122 may employ one or more techniques to process these AE signals. Some of the techniques may include super imposition of AE signals on the reference or theoretical event map, performing Fourier transform and specifically short time Fourier transform on the AE signals, correlation of the AE signals. Also, Spatial Analysis, Frequency Analysis, and Time Frequency Analysis are some of other techniques that may be used to process the AE signals. In addition, the processing module 122 may also be configured to display these processed signals and/or the identified anomalies in the engine subsystem 104 on the display unit 124. The aspect of detecting the anomalies in the engine subsystem 104 will be explained in greater detail with reference to FIG. 2. In one embodiment, the ADM 102 may be a kit that is operatively coupled to an existing engine subsystem 104 to detect anomalies in the engine subsystem 104.

[00291 Referring to FIG. 2, a flow chart 200 illustrating a method for detecting an anomaly in a power assembly of an engine subsystem, in accordance with aspects of the present disclosure, is depicted. For ease of understanding of the present disclosure, the method is described with reference to the components of FIG. 1. The method begins at step 202, where an AE signal corresponding to at least one cylinder in the power assembly 106 may be sensed. To that end, at least one of the AE sensors 112, 114 may be employed to sense the AE signal corresponding to at least one cylinder in the power assembly 106. In particular, the first AE sensor 112 is disposed on one of the cylinders in the left bay 126 of the engine subsystem 104 to sense an AE signal corresponding to the left bay 126 of the engine subsystem 104. Similarly, the second AE sensor 114 is disposed on one of the cylinders in the right bay 128 of the engine subsystem 104 to sense an AE signal corresponding to the right bay 128 of the engine subsystem 104. These AE signals may be representative of stress waves in the engine subsystem 104. In one embodiment, the stress waves may include or may be generated due to combustion noise and/or mechanical noise of at least one cylinder in the power assembly 106.

[0030] Subsequently, at step 204, a pressure signal corresponding to one or more cylinders may be detected. To that end, the pressure sensor 116 is coupled to the decompression valve 110 of at least one cylinder to detect the pressure signal. The pressure signal may be representative of in-built pressure of the cylinder upon which the pressure sensor 116 is mounted. The pressure signal may be employed as a reference signal to identify events of the cylinders in the left bay 126 and/or the right bay 128 of the engine subsystem 104.

[0031] In addition, at step 206, event data corresponding to at least one cylinder in the engine subsystem 104 may be determined based on the AE signals and the pressure signal. In one example, the processing module 122 is configured to determine the event data. More specifically, the processing module 122 is configured to receive the AE signals from the first AE sensor 112 and the second AE sensor 114 and the pressure signal from the pressure sensor 116. Thereafter, the processing module 122 is configured to convert the AE signals from a time domain to a crank angle domain based on the rotational speed information of the crank 130 received from the engine control unit 108.

[0032] Furthermore, each of these AE signals may in turn include a plurality of sub-signals corresponding to one or more cycles. The term "cycle" is used to refer to a time period corresponding to a set of actions that may include suction, compression, ignition, and exhaust of air/fuel in the cylinder. By way of example, in a four stroke engine, the term "cycle" may correspond to rotation of the crank 130 from about 0 degrees to about 720 degrees. Also, each sub-signal may be representative of information corresponding to events occurring in one cycle. Further, these sub-signals may be superimposed on each other to identify repeatability of events in the received acoustic emission signals. For example, a portion of each sub-signal corresponding to the highest amplitude may be representative of a combustion event in that sub-signal. Accordingly, when the sub-signals are superimposed on each other, the highest amplitude of each of the sub-signals may be aligned with each other. This repeatability of events may be identified to verify the occurrence of events and/or a sequence of events in one or more cylinders. In one example, the sequence of events may include the inlet valve open event, the outlet valve close event, the combustion event, the inlet valve close event, and the outlet valve open event. Also, by verifying the repeatability of events, any missing event in the sequence of events may be identified.

[0033] Upon receiving the AE signals from the AE sensors 112, 114, the AE signals are converted from a time domain to a crank angle domain. More specifically, the rotational speed information of the crank 130 may be used to determine the cycle time of the crank 130. Further, the cycle time of the crank 130 and a determined crank angle of the AE signals corresponding to each of the events that occur in the cycle time may be used to convert the AE signals from the time domain to the crank angle domain. As previously noted, the processing module 122 may be employed to convert the AE signals from the time domain to the crank angle domain. In a similar manner, the processing module 122 may be configured to convert the pressure signal from the time domain to the crank angle domain based on the rotational speed information of the crank 130. Furthermore, the processing module 122 may be configured to superimpose the converted pressure signal on the converted AE signals such that the crank angles of the converted AE signals align with the crank angles of the converted pressure signal.

[0034] In accordance with aspects of the present disclosure, the pressure signal may be employed as a reference signal to identify the events of a particular cylinder upon which the pressure sensor 116 is mounted or disposed upon. For example, if the pressure sensor 116 is mounted on the decompression valve 110 of a first cylinder Ci in the left bay 126, the pressure signal provides information regarding the in-built pressure of the first cylinder Cj. In the left bay 126, this in-built pressure information may be used to determine the events occurring in the first cylinder C\. Further, this pressure signal is superimposed on the AE signals in such a way that the crank angle of the pressure signal is aligned with the corresponding crank angle of the AE signals. Consequently, when the pressure signal is superimposed on the AE signals, the determined events of the first cylinder Ci obtained from the pressure signal align with the events obtained from the AE signals. Thus, the pressure signal is used as a reference signal to identify the events of at least one cylinder in the engine subsystem 104. In accordance with further aspects of the present disclosure, the superimposed AE signals and the pressure signal may be aligned with the reference event map to identify the events corresponding to at least one cylinder in the engine subsystem 104. The reference event map may include one or more reference event data corresponding to one or more cylinders in the engine subsystem 104.

[0035] Moreover, since the events of one cylinder, for example, the first cylinder d in the left bay 126, is determined, the events of other cylinders in the engine subsystem 104 may also be determined based on a relationship between the cylinders. Particularly, each event in the cylinder may occur at a respective angle of the crank 130 and the events in each of the cylinders may have different offsets. For example, at least two cylinders may fire at every 120 degrees.

[0036] Additionally, each of the events is associated with a particular range of frequencies. Accordingly, the frequency range in the AE signal corresponding to each event may be determined by processing the AE signal with a short time Fourier Transform, for example. Anomalies in any of the components in the power assembly may result in a significant change in the frequency spectrum corresponding to that event. This change in the frequency spectrum may be employed to detect faults or defects in the corresponding event or cylinder.

[0037] Further, at step 208, upon determining or identifying the events in each of the cylinders in the engine subsystem 104, an anomaly in at least one cylinder may be detected. In accordance with aspects of the present disclosure, the anomaly may be detected by comparing the determined combustion event data with reference event data. The reference event data may be obtained from the reference event map, for example. The processing module 122 is used to detect any anomalies in the cylinders. Particularly, the processing module 122 may be configured to identify at least one parameter associated with one or more events in the cylinder. This parameter may include peak amplitude, rise time, time duration, root mean square (RMS) voltage, signal strength, energy, and the like. Moreover, the processing module 122 may be configured to compare the identified parameter with reference event data to detect the anomaly in the cylinder. For example, the processing module 122 may be configured to determine the signal strength of the combustion event of the first cylinder Q in the left bay 126 of the engine subsystem 104. This signal strength of the combustion event may be compared with a reference signal strength data of the combustion event of the first cylinder Ct. The processing module 122 may be configured to detect the type of anomaly in the first cylinder Ci based on this comparison. For example, if the above comparison indicates low signal strength of the combustion event, then the anomaly may be considered as a piston ring failure in the first cylinder Q. The type of anomaly may include fuel injector failure, cylinder head cracks, piston top land cracks, piston crown cracks, piston skirt cracks cylinder liner wear, piston ring failure, scuffing, bore distortion, lubrication friction between the piston and cylinder, valve defects, bent con rod, and big end and small end bushing wear.

[0038] Turning now to FIG. 3, a graphical representation 300 of an acoustic emission signal, in accordance with aspects of the present disclosure, is depicted. The graphical representation of the acoustic emission signal shown in FIG. 3 is an example of an AE signal sensed from one cylinder. Reference numerals 302, 304, 306 are representative of AE sub-signals corresponding to different cycles of the engine subsystem 104. These AE sub-signals 302, 304, 306 are in a time domain and depict different events of the cylinder at different time intervals.

[0039] Further, reference numeral 308 represents a signal waveform of the AE signal obtained by superimposing the sub-signals 302, 304, 306. It may be noted that the AE signal 308 is in the crank angle domain. Moreover, the signal waveform 308 of the AE signal has two peaks 310, 312 that are representative of the firing angle or the combustion event of two cylinders in the engine subsystem 104. For example, in one cycle at least two cylinders, one cylinder from the left bay 126 and the other cylinder from the right bay 128, may fire at a defined offset. Also, one cycle corresponding to a cylinder may be completed with the crank 130 rotating from 0 degree to 720 degrees.

[0040] Reference numerals 314, 316, 318 represent signal waveforms of the AE signal 308 converted from the crank angle domain to a frequency domain. Each of the signal waveforms 314, 316, 318 represents different frequency components of the AE signal 308. Particularly, the processing module 122 may be configured to process the AE signal 308 using a FFT decomposition technique, for example, to convert the AE signal 308 from the crank angle domain to the frequency domain. These signal waveforms 314, 316, 318 in the frequency domain may be utilized to identify events occurring at different frequencies. Also, the signal waveforms 314, 316, 318 may be employed to filter signals for a particular band of frequencies to further analyze events in that frequency band. Further, the filtered signals may be compared with the reference signal data to identify anomalies in the engine subsystem 104. Thus, by converting the AE signals from the crank angle domain to the frequency domain, a frequency spectrum of a particular event may be determined. Also, anomalies in this determined frequency spectrum may be easily monitored.

[004] FIG. 4 is a graphical representation 400 of acoustic emission sub-signals 402, 404, 406 that are superimposed on one another, in accordance with aspects of the present disclosure. These AE sub-signals 402, 404, 406 are example sub-signals obtained by the processing module 122 and displayed on the display unit 124. In the example of FIG. 4, the signal waveforms represent a first AE sub-signal 402 corresponding to a tenth cycle, a second AE sub-signal 404 corresponding to an eleventh cycle, and a third AE sub-signal 406 corresponding to a twelfth cycle. As depicted in FIG. 4, the events in one of the cycles, for example the tenth cycle one generally aligned with corresponding events in the other cycles, such as eleventh and twelfth cycles. For example, in FIG. 4, the combustion events that have highest amplitude/signal strength in each of the cycles are substantially aligned with each other. Thus, the AE sub-signals in FIG. 4 aid in studying repeatability of events in one or more cycles. If an event does not occur in one of the cycles, this repeatability of evenis may be used to identify any missing events, which is depicted in FIG. 5.

[0042] Referring to FIG. 5, a graphical representation 500 of acoustic emission sub-signals 502, 504, 506, in accordance with aspects of the present disclosure, is depicted. The signal waveforms in FIG. 5 are similar to the signal waveforms 402, 404, and 406 in FIG. 4 except that a peak representing a combustion event in one of the AE sub-signals 502, 504, 506 is missing. In the example of FIG. 5, a peak of the sub-signal 504 is missing between crank angles 200 and 300. This missing peak may be due to a fault in a corresponding cylinder. For example, if there is a piston ring failure, the combustion event may not occur in the cylinder and thus, the peak between the crank angles 200 and 300 representing this combustion event may be absent in the AE sub-signal 504. Thus, by superimposing the AE sub-signals, events missing in one cylinder or faulty events in the cylinder may be easily identified.

[0043] FIG. 6 is a graphical representation 600 of a comparison of a pressure signal with the acoustic emission signals, in accordance with aspects of the present disclosure. Reference numeral 602 represents a pressure signal sensed by the pressure sensor 116 (see FIG. 1) disposed on a cylinder. Also, the pressure signal 602 is shown in a time domain. Further, the pressure signal 602 in the time domain is converted to a crank angle domain and is represented by reference numeral 604. The pressure signal 604 in the crank angle domain shows that the magnitude or signal strength is very high during the combustion event of the cylinder upon which the pressure sensor 116 is mounted. For example, in-built pressure of the cylinder is very high between the crank angles 300 and 600 of the pressure signal 604, as depicted in FIG. 6.

[0044] Furthermore, reference numeral 606 represents a comparison of an AE signai 608 and a pressure signal 610. Particularly, when the pressure signal 610 is superimposed on the AE signal 608, the peak of the pressure signal 610 representing the combustion event of the cylinder is aligned with the peak of the AE signal 608 representing a combustion event of the corresponding cylinder. Thus, comparing the pressure signal 610 with the AE signal 608 aids in identifying the events in the AE signal.

[0045] The various embodiments of the system and the method for detecting an anomaly in the power assembly aid in early detection of faults in the engine subsystem. By detecting such faults in the engine subsystem, any losses that may occur due to crank case over¬pressure, knocking, piston slapping, piston seizure, and/or valve failure in the power assembly may be easily prevented. Also, by detecting faults in the power assembly, further degradation of the components may be prevented, which in turn improves the performance of the engine subsystem. Additionally, the cost of diagnosing and maintaining the engine subsystem is substantially reduced with the use of the exemplary diagnostic device. Moreover, the diagnostic device may be used for detecting and localizing any power assembly issue after a CCOP trip in the locomotive. Furthermore, the exemplary diagnostic device may be a kit that may be operatively coupled or retrofit to an existing engine to detect anomalies in the engine.

[0046] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

CLAIMS:

1. A device for monitoring a power assembly of an engine subsystem, the device comprising:

at least one acoustic emission sensor operatively coupled to at least one cylinder in the power assembly and configured to sense an acoustic emission signal corresponding to the at least one cylinder;

a pressure sensor operatively coupled to the at least one cylinder and configured to sense a pressure signal corresponding to the at least one cylinder;

a processing module operatively coupled to the at least one acoustic emission sensor and the pressure sensor and configured to:

determine event data of the at least one cylinder based on the acoustic emission signal and the pressure signal; and

detect an anomaly in the at least one cylinder based on the determined event data.

2. The device of claim 1, wherein the acoustic emission sensor is configured to sense the acoustic emission signal associated at least with stress waves propagating on the at least one cylinder.

3. The device of claim 1, wherein the pressure sensor is configured to sense the pressure signal associated with in-built pressure of the at least one cylinder.

4. The device of claim 1, further comprising an engine control unit operatively coupled to a crank of the power assembly and configured to determine rotational speed of the crank.

5. The device of claim 4, wherein the processing module is configured to:

convert the acoustic emission signal from a time domain to a crank angle domain based on the rotational speed of the crank;

convert the pressure signal from the time domain to the crank angle domain based on the rotational speed of the crank; and

compare the converted pressure signal with the converted acoustic emission signal to determine the event data of the at least one cylinder.

6. The device of claim 5, wherein the processing module is configured to:

receive the acoustic emission signal from the at least one acoustic emission sensor, wherein the acoustic emission signal comprises a plurality of sub-signals, and wherein each of the sub-signals is associated with a corresponding cycle of a plurality of cycles;

compare the plurality of sub-signals with each other to identify a plurality of events in the received acoustic emission signal; and

convert the sub-signals from the time domain to the crank angle domain based on the rotational speed of the crank.

7. The device of claim 6, wherein the plurality of events comprises one or more of an inlet valve open event, an outlet valve close event, a combustion event, an inlet yalve close event, and an outlet valve open event of the at least one cylinder.

8. The device of claim 5, wherein the processing module is configured to:

identify a crank angle corresponding to the converted acoustic emission signal;

identify a crank angle corresponding to the converted pressure signal; and

superimpose the converted pressure signal on the converted acoustic emission signal such that the crank angle of the converted acoustic emission signal is aligned with the crank angle of the converted pressure signal.

9. The device of claim 1, wherein the processing module is configured to:

identify at least one parameter associated with the determined event data; and

compare the identified parameter with a corresponding parameter of reference event data to detect the anomaly in the at least one cylinder.

10. The device of claim 9, wherein the at least one parameter comprises an peak amplitude, a rise time, time duration, root mean square voltage, signal strength, energy of the acoustic emission signal.

11. The device of claim 1, where in the processing module is configured to:

store a reference event map of the engine subsystem; and

compare the acoustic emission signal with the reference event map to detect the anomaly in the at least one cylinder.

12. The device of claim 1, wherein the anomaly comprises combustion noise or mechanical noise of the at least one cylinder in the power assembly.

13. A method for detecting an anomaly in a power assembly, the method comprising:

sensing an acoustic emission signal corresponding to at least one cylinder in the power assembly;
detecting a pressure signal corresponding to the at least one cylinder;

determining event data corresponding to the at least one cylinder based on the acoustic emission signal and the pressure signal; and

detecting the anomaly in the power assembly by comparing the determined event data with reference event data.

14. The method of claim 13, further comprising determining rotational speed of a crank operatively coupled to the at least one cylinder.

15. The method of claim 14, wherein determining the event data corresponding to the at least one cylinder comprises:

converting the acoustic emission signal from a time domain to a crank angle domain based on the rotational speed of the crank;

converting the pressure signal from the time domain to the crank angle domain based on the rotational speed of the crank; and

comparing the converted pressure signal with the converted acoustic emission signal to determine the event data corresponding to the at least one cylinder.

16. The method of claim 15, wherein converting the acoustic emission signal from the time domain to the crank angle domain comprises:

receiving the acoustic emission signal comprising a plurality of sub-signals, wherein each of the sub-signals is associated with a corresponding cycle of a plurality of cycles;

superimposing the plurality of sub-signals on each other to identify a plurality of events in the received acoustic emission signal, wherein the plurality of events comprises at least one of an inlet valve open event, an outlet valve close event, a combustion event, an inlet valve close event, and an outlet valve open event of the at least one cylinder; and

converting the superimposed plurality of sub-signals from the time domain to the crank angle domain based on the rotational speed of the crank.

17. The method of claim 15, wherein comparing the converted pressure signal with the converted acoustic emission signal comprises:

identifying a crank angle of the converted acoustic emission signal;

identifying a crank angle of the converted pressure signal; and

aligning the converted pressure signal with the converted acoustic emission signal such that the crank angle of the converted acoustic emission signal is aligned with the crank angle of the converted pressure signal.

18. The method of claim 13, wherein detecting the anomaly in the power assembly comprises:
identifying at least one parameter associated with the determined event data; and

comparing the identified parameter with a corresponding parameter of the reference event data to detect the anomaly in the at least one cylinder.

19. A diagnostic kit, comprising:

at least one acoustic emission sensor operatively coupled to at least one cylinder in a power assembly and configured to sense an acoustic emission signal corresponding to the at least one cylinder;

a pressure sensor operatively coupled to the at least one cylinder and configured to sense a pressure signal corresponding to the at least one cylinder; and

a processing module operatively coupled to the at least one acoustic emission sensor and the pressure sensor and configured to detect an anomaly in the at least one cylinder based on the acoustic emission signal and the pressure signal corresponding to the at least one cylinder.

20. The diagnostic kit of claim 19, wherein the processing module is configured to:

determine combustion event data of the at least one cylinder based on the acoustic emission signal and the pressure signal; and

detect the anomaly in the at least one cylinder by comparing the determined combustion event data with reference event data.